Arch Exp Veterinarmed, 1975, 29(2), 211 - 5 {Sodium thiocyanate as a protective agent in intensive calf fattening . Brief report}; Rotermund L et al.; Daily administration of sodium thiocyanate at 750 mg a calf for the first three weeks in the fattening stalls reduced the occurrence of illness by 60% . This protective effect seemed to persist during the following weeks without additional treatment . Addition of the thiocyanate to the food may be beneficial through a nutritive effect. Vopr Onkol, 1975, 21(4), 37 - 40 {Effect of guanine and guanosine-2',3' phosphate on sarcolysin-H3 binding to the DNA of rat liver}; Dzhioev FK et al.; Rats were injected sarcolysin-H3 in a dose of 200 or 500 mC per rat . In animals sacrificed 30, 60 and 90 minutes following sarcolysin-H3 injection an increased radioactivity of DNA was noted that indicates binding of sarcolysin-H3 or its labelled derivatives to DNA . Guanine or quanosine-2', 3' monophosphate injected in animals decreased binding of sarcolysin-H3 to the rat liver DNA (maximum reduction of DNA radioactivity in 47%) . In the experiments in vitro guanosine-2', 3' phosphate inhibited sarcolysin-H3 binding to DNA isolated from E . coli . A protective effect of quanine and guanosine-2', 3' phosphate with respect to DNA alkylation seems to be considerably conditioned by a competitive action of these nucleophils. Neoplasma, 1975, 22(4), 361 - 84 Function of the UVR marker in dark repair of DNA molecules; Sedli-kova M et al.; It had been found earlier that the excision repair mechanism in E . coli B/R Hcr+ could be depressed by preirradiation, amino acid and thymine starvation; such an interference proved to have no appreciable influence on survival after ultraviolet irradiation . A comparison between Hcr+ and Hcr- cells had revealed that the former were capable of tolerating a greater amount of unexcised dimers than the latter . In this paper it is demonstrated that the above-mentioned pretreatment will depress excision activity also in cultures of E . coli K12 and E . coli 15T- both strains of the uvr+ rec+ genotype . A comparison of two E . coli K12 strains of the uvr+ and uvr- genotype shows that uvr+ cells also have a greater capacity to tolerate unexcised dimers . To throw light on the nature of that increased capacity to tolerate unexicsed dimers we have compared restoration of DNA daughter chains in cells of the uvr+ and uvr- genotype and found that integrity of uvr loci is a conditio sine qua non for an effective restoration of daughter chains, but that depression of excision activity by the mentioned pretreatment does not influence restoration of DNA daughter chains . This suggest that uvr loci are involved not only in excision but also in postreplication mechanism of DNA repair. Mol Gen Genet, 1975, 138(2), 143 - 55 Independence of F replication and chromosome replication in Escherichia coli; Pritchard RH et al.; Data are presented which show that F replication is not coupled to any stage of the replication cycle of the host chromosome or to cell division, and is probably not related to surface area . It is also shown that the initiation mass of F increases progressively as the growth rate increases, the number of copies of F per unit of mass falling by half between doubling times of 0.8 and 2.7 generations per hour . It is further shown that the presence of an F particle does not influence the initiation mass of the chromosome. Mol Gen Genet, 1975, 138(2), 127 - 41 The effect of gene concentration and relative gene dosage on gene output in Escherichia coli; Chandler MG et al.; The differential rate of synthesis of several Escherichia coli gene products was measured under conditions in which the average number of copies of the corresponding chromosomal gene had been changed by altering the replication velocity of the chromosome . The data show that in steady state exponential cultures the output of genes in a fully repressed, fully derepressed, or non-repressible state is proportional to the average number of copies of the gene per unit mass (gene: mass ratio) and does not depend on the number of copies of the gene relative to all other genes (gene: DNA ratio) . In contrast, the output of a gene which was under regulation by endogenously generated effectors was independent of such changes in gene frequency . The relationship found between the number of copies of a gene per unit of cell mass and enzyme output provides a new method for determining the location of the chromosome origin and the direction of replication in bacteria. Folia Microbiol (Praha), 1975, 20(5), 433 - 8 The role of immune pig colostrum, serum and immunoglobulins IgG, IgM, and IgA, in local intestinal immunity against enterotoxic strain in Escherichia coli O55 in germfree piglets; Miller I et al.; The protective effect of pig immune colostrum, serum and immunoglobulins IgG, IgM and IgA against the enterotoxic strain of Escherichia coli O55, was studied in newborn germfree piglets . This strain produced accumulation of fluid and dilatation of intestine when injected into the ligated ileal segment of germfree piglets, which is considered to be the typical effect of enterotoxins . Erosion of the intestinal epithelium and penetration of bacteria into the submucosa were also observed . Immune serum, colostrum and all the immunoglobulin classes used produced a local protective effect, IgA being most effective . The mechanism of protection conferred by these immunoglobulins is discussed with respect to the possible pathogenic action of enterotoxic Escherichia coli O55 in the intestinal tract of immunologically virgin germfree piglets. Folia Microbiol (Praha), 1975, 20(5), 382 - 8 Possibilities of the conjugation process in mycobacteria; Konicek J et al.; Results obtained when studying conjugation in mycobacteria by means of different methods are summarized . The method of conjugation on surface of a solid complete medium was tested with different auxotrophic mutants of different strains of Mycobacterium smegmatis . It was not possible to obtain positive results even by means of the above method . This was probably due to unsuitability of the chosen strains of Mycobacterium smegmatis . Preparation of the donor strain by transfer of the F factor from Escherichia coli F'ORF 1 ade+ lac+ pro+ to Mycobacterium phlei PA ade Stmr by means of sexduction is described . Frequency of the phenotype PA ade+ Stmr increased in the average by two and a half orders of magnitude with respect to the control, however, a further transfer from cultures of the cells ade+ Stmr to cells ade could not be demonstrated . Experiments aimed at transferring the R factor from strains Escherichia coli K-12 to Mycobacterium phlei were unsuccessful. Basic Life Sci, 1975, 5B, 567 - 76 Genetic control of radiation sensitivity and DNA repair in Neurospora; Schroeder A; Radiation sensitivity in the fungus Neurospora crassa is under the control of at least eight distinct loci and is also affected by cytoplasmic factors . Although radiation-sensitive mutants which affect inter- or intragenic meiotic recombination have not been isolated, mutants which are defective in the repair of pyrimidine dimers have been found . Evidence from both mutational and biochemical studies shows that Neurospora has an excision-repair system for pyrimidine dimers which is very similar to the one found in Escherichia coli . Wild-type strains excise dimers, but two mutants, uvs2 and upr1, are UV sensitive and excision defective . Like the E . coli excision-defective mutants, the Neurospora mutants show a greatly increased frequency of UV-induced mutation at low UV doses, and they do not affect recombination . However, they differ from the E . coli mutants in being significantly more sensitive to ionizing radiation than wild-type strains . A third mutant, uvs6, resembles the DNA polymerase-I-negative mutants of E . coli . It is sensitive to both UV and X-irradiation, has a wild-type pattern of UV-induced mutation, and increases spontaneous deletion frequencies . Its polymerases have not been examined . The high frequency of UV-induced mutation in excision-defective strains suggests that a "mutation prone" system of DNA repair exists in Neurospora . This is supported by the ppoperties of the uvs3 strain, which shows no UV-induced mutation . Like postreplication-repair-defective E . coli mutants, it is UV and ionizing radiation sensitive and sensitive to both monofunctional and bifunctional alkylating agents . This mutant is sterile . As expected, the double mutant uvs3 upr1 strain is much more sensitive to UV than either single-mutant strain . Two other loci, muc2 and gs6, may affect DNA repair . Mutations at the five remaining loci, uvs1, uvs4, uvs5, gs3, and gs20, lead to a constellation of properties unlike those of any DNA-repair-deficient E . coli mutant . The occurrence of these mutations could mean that other DNA repair systems exist in Neurospora, or, like the lon mutants of E . coli, they might indicate that cell sensitivity to radiation damage can be increases in other ways. Basic Life Sci, 1975, 5B, 487 - 95 Repair of cross-linked DNA in Escherichia coli; Cole RS et al.; The repair of DNA containing interstrand cross-links in Escherichia coli was studied by following the temporal sequence of DNA-related metabolic events in cells exposed to psoralen plus light . Mutations in some genes controlling replication, recombination, and repair strongly influence these specific events . Results reported here are consistent with a cross-link repair mechanism involving sequential excision and recombination. Basic Life Sci, 1975, 5B, 473 - 81 DNA repair in DNA-polymerase-deficient mutants of Escherichia coli; Smith DW et al.; Escherichia coli mutants deficient in DNA polymerase I, in DNA polymerases I and II, or in DNA polymerase III can efficiently and completely execute excision-repair and postreplication repair of the UV-damaged DNA at 30 degrees C and 43 degrees C when assayed by alkaline sucrose gradients . Repair by Pol I- and Pol I-, Pol II- cells is inhibited by 1-beta-D-arabinofuranosylcytosine (araC) at 43 degrees C but not at 30 degrees C, whereas that by Pol III- cells is insensitive to araC at any temperature . Thus, either Pol I or Pol III is required for complete and efficient repair, and in their absence Pol II mediates a limited, incomplete dark repair of UV-damaged DNA. Basic Life Sci, 1975, 5B, 453 - 8 Near-UV photoproduct(s) of L-typtophan: an inhibitor of medium-dependent repair of X-ray-induced single-strand breaks in DNA which also inhibits replication-gap closure in Escherichia coli DNA; Yoakum G et al.; Near-UV photoproducts of L-tryptophan (TP), which are especially toxic for recombination-deficient (rec) mutants, were found to inhibit medium-dependent repair of X-ray-induced single-strand breaks . This inhibitor also slows the rate of closure of replication gaps, suggesting that these two processes may have a common pathway (or share a required step which TP can inhibit). Basic Life Sci, 1975, 5A, 89 - 101 Kinetics of photoreactivation; Harm W; This paper summerizes experimental work (most of which is published) in which light flashes were used for an analysis of photoenzymatic repair in vivo and in vitro . The method permits determination of the reaction rate constants for the formation, dark dissociation, and repair photolysis of enzyme-substrate complexes under various conditions, and estimation of the number of photoreactivating enzyme molecules present . Investigation of these characteristics is basic for understanding of the overall photoreactivation kinetics observed in biological systems, its dependence on experimental parameters, and possibly its biological significance. Basic Life Sci, 1975, 5A, 47 - 50 DNA turnover and strand breaks in Escherichia coli; Hanawalt P et al.; The extent of DNA turnover has been measured in a dnaB mutant of Escherichia coli, temperature sensitive for semiconservative DNA replication . At the nonpermissive temperature about 0.02% of the deoxynucleotides in DNA are exchanged per generation period . This turnover rate is markedly depressed in the presence of rifampicin . During thymine starvation strand breaks accumulate in the DNA of E . coli strains that are susceptible to thymineless death . Rifampicin suppresses the appearance of these breaks, consistent with our hypothesis that transcription may be accompanied by repairable single-strand breaks in DNA . DNA turnover is enhanced severalfold in strands containing 5-bromodeoxy-uridine in place of thymidine, possible because the analog (or the deoxyuridine, following debromination) is sometimes recognized and excised. Basic Life Sci, 1975, 5A, 399 - 404 The role of DNA polymerase I in genetic recombination and viability of Escherichia coli; Smirnov GB et al.; The rate of formation of high-molecular-weight daughter DNA in the conditionally lethal double mutant polA12 uvrE502, incubated at nonpermissive temperature, was slower than that in the single polA12 mutant . There exist at least two pathways determining viability of Escherichia coli cells: one of them is dependent on polA+ and recB+ genes, while another is polA+ and recB+ genes, while another is polA recB independent but requires the uvrE+ gene and can be blocked by exonuclease I . The RecF but not the RecBC pathway of genetic recombination was found to be absolutely dependent on the polymerizing activity of DNA polymerase I . The involvement of DNA polymerase I in genetic recombination in the recB- C- sbsB strain and viability in the uvrE- or recB- strains suggest the existence of the common steps required for the accomplishing of the RecF pathway of recombination and for viability of E . coli. Basic Life Sci, 1975, 5A, 383 - 8 Indirect suppression of radiation sensitivity of a recA- strain of Escherichia coli K12; Mount DW et al.; It has been shown previously that the radiation sensitivity of LexA strains of Escherichia coli K-12 can be suppressed by thermosensitive mutations (designated tsl) that are closely linked to the lexA locus . These are thought to be intragenic suppressors that reduce the activity of the diffusible product that gives rise to the LexA- phenotype (Mount et al., 1973) . When a recA mutation is crossed into a suppressed tsl- strain, the extreme radiation sensitivity usually conferred by a recA mutation is considerably reduced without any detectable change in genetic recombination deficiency . Suppression of UV sensitivity depends upon the activity of the uvrA+ product . We propose that at least part of the radiation sensitivity of a recA- strain is due to a DNA repair defect that is different from inability to perform genetic exchanges and depends upon the presence of the lexA+ product . We hypothesize that the lexA+ product is a repressor of the synthesis of repair enzymes . In recA+ cells with DNA lesions, repressor is inactivated leading to enzyme induction but this does not occur in recA- cells . tsl mutations inactivate repressor leading to constitute enzyme synthesis and bypassing the need for recA+ product to inactivate the lexA+ product. Basic Life Sci, 1975, 5A, 369 - 78 Thermal enhancement of ultraviolet mutability in a dnaB uvrA derivative of Escherichia coli B/r: evidence for inducible error-prone repair; Witkin EM; DNA damage triggers coordinate expression of a cluster of diverse functions in Escherichia coli, including prophage induction, filamentous growth, and "aberrant" reintiation of DNA replication at the chromosomal origin . The "SOS repair" hypothesis proposes that one of these coordinately inducible functions is an error-prone system of DNA repair ("SOS repair") which is responsible for ultraviolet mutagenesis . In dnaB strains, incubation of 42 degrees C stops DNA synthesis and induces lambda prophage and should, therefore, also induce the postulated error-prone repair activity . Thermal posttreatment of a dnaB urvA derivative of E . coli B/r is found to enhance the yield of ultraviolet-light-induced mutations as much as 50-fold, while having no such effect in the dnaB+ parent strain . The results support the SOS repair hypothesis . The possibility is discussed that the inducible repair system is a mutagenic DNA polymerase. Basic Life Sci, 1975, 5A, 355 - 67 SOS repair hypothesis: phenomenology of an inducible DNA repair which is accompanied by mutagenesis; Radman M; A hypothesis was proposed several years ago that Escherichia coli posses an inducible DNA repair system ("SOS repair") which is also responsible for induced mutagenesis . Some characteristics of the SOS repair are (1) it is induced or activated following damage to DNA, (2) it requires do novo protein synthesis, (3) It requires several genetic functions of which the best-studied are recA+ and lex+ of E . coli, and (4) the physiological and genetic requirements for the expression of SOS repair are suspiciously similar to those necessary for the prophage induction . The SOS repair hypothesis has already served as the working hypothesis for many experiments, some of which are briefly reviewed . Also, some speculations are presented to stimulate further discussions and experimental tests. Basic Life Sci, 1975, 5A, 325 - 9 Postreplication repair gap filling in an Escherichia coli strain deficient in dnaB gene product; Johnson RC; Gaps in daughter-strand DNA synthesized after exposure of Escherichia coli E279 to ultraviolet light are filled during reincubation at 30 degrees C for 20 min . Escherichia coli E279 is phenotypically DnaB- when incubated at 43 degrees C . Cells incubated at 43 degrees C were tested for their ability to complete postreplication repair gap filling . It is concluded that the dnaB gene product is essential for postreplication repair gap filling and that the inhibition seen is not initially the result of degradation. Basic Life Sci, 1975, 5A, 317 - 20 Distribution of pyrimidine dimers during postreplication repair in UV-irradiated excision-deficient cells of Escherichia coli K12; Ganesan A; During postreplication repair in excision-deficient mutants of Escherichia coli K-12, pyrimidine dimers are gradually lost from UV-irradiated DNA . Our data indicate that dimers are transferred, by a process which may involve genetic exchange, into daughter strands made after irradiation . Dimer transfer appears to continue through several rounds of replication, resulting in the gradual dilution of dimers into successive generations of DNA molecules. Basic Life Sci, 1975, 5A, 313 - 6 Ultraviolet-light-induced incorporation of bromodeoxyuridine into parental DNA of an excision-defective mutant of Escherichia coli; Ley RD; Bromodeoxyuridine-containing regions approximately 1.5 X 10(4) Nucleotides in length, and at intervals equivalent to the pyrimidine dimer content of the DNA, have been observed in the parental DNA of an excision-defective strain of Escherichia coli exposed to 10 ergs mm-2 at 254 nm followed by prolonged incubation in the presence of bromodeoxyuridine. Basic Life Sci, 1975, 5A, 301 - 6 Analysis of temperature-sensitive recB and recC mutations; Kushner SR; The in vivo pleiotropic effects associated with the temperature-sensitive recB270 and recC271 mutations have been correlated with the in vitro behavior of the recBC nucleases coded for by these alleles . The ATP-dependent breakdown of double-stranded DNA is essential for cell viability, radiation repair, and genetic recombination . Temperature sensitivity can be suppressed in vitro and in vivo. Basic Life Sci, 1975, 5A, 245 - 54 Repair replication in permeabilized Escherichia coli; Masker WE et al.; We have examined the modes of DNA synthesis in Escherichia coli strains made permeable to nucleoside triphosphates by treatment with toluene . In this quasi in vitro system, polymerase-I-deficient mutants exhibit a nonconservative mode of synthesis with properties expected for the resynthesis step of excision-repair . This UV-stimulated DNA synthesis can be performed by either DNA polymerase II or III and it also requires the uvrA gene product . It requires the four deoxynucleoside triphosphates; but, in contrast to the semiconservative mode, the ATP requirement can be partially satisfied by other nucleoside triphosphates . The ATP-dependent recBC nuclease is not involved . The observed UV-stimulated mode of DNA synthesis may be part of an alternate excision-repair mechanism which supplements or complements DNA-polymerase-I-dependent repair in vivo. Basic Life Sci, 1975, 5A, 225 - 34 Exonuclease VII of Escherichia coli; Chase JW et al.; A new exonuclease of Escherichia coli K12, exonuclease VII, has been purified 1700-fold and characterized . The enzyme is specific for single-stranded DNA and can initiated hydrolysis at both 5' and 3' termini . It is also capable of thymine-dimer excision in vitro . The limit products of the reaction are oligonucleotides, predominantly in the range of tetramers to dodecamers . DNA is hydrolyzed by the enzyme in a processive fashion . Mutants of E . coli have been isolated having reduced levels of exonuclease VII activity in crude extracts . Mapping studies place the exonuclease VII locus between 45 and 56 minutes on the E . coli K12 linkage map. Basic Life Sci, 1975, 5A, 219 - 23 Involvement of Escherichia coli DNA polymerase-I-associated 5' in equilibrium 3' exonuclease in excision-repair of UV-damaged DNA; Heyneker HL et al.; From comparative studies between Escherichia coli PolA107 cells (lacking 5' in equilibrium 3' exonucleoytic activity associated with DNA polymerase I) and the isogenic wild-type strain, and between the purified DNA polymerase I preparations isolated from these strains, it can be concluded that the 5' in equilibrium 5' exonuclease is involved in excision of pyrimidine dimers in E . coli . Evidence is presented that the polA107 mutation is located on that part of the DNA polymerase I gene coding for the small fragment on which 5' in equilibrium 3' exonucleolytic activity is found. Basic Life Sci, 1975, 5A, 213 - 8 The role of DNA polymerase I in excision-repair; Glickman BW; The ability of three different DNA polymerase I mutants of Escherichia coli to carry out excision-repair was examined . Strains having the same genetic origin but carrying either the polAl, polA107, resAl, or pol+ alleles were compared . The rate of ultraviolet-induced dimer excision was slightly reduced, relative to that found in Pol+ strains, in the PolAl strains; greatly reduced in the PolA107 strains; and found not to occur in the resAl strain . Ultraviolet-light-induced repair synthesis as determined by the ultraviolet-stimulated incorporation of 3H-labeled 5-bromo-2'-deoxyuridine into DNA of the parental density showed that the polAl mutation resulted in an increase in repair replication, while the presence of the polA107 allele caused a reduction in the amount of repair synthesis relative to that of the Pol+ strain . The ResAl strain, however, showed no ultraviolet stimulation of the incorporation of the density label . These observations indicate that DNA polymerase I plays a key role in the excision-repair process in E . coli. Basic Life Sci, 1975, 5A, 183 - 90 The Escherichia coli UV endonuclease (correndonuclease II); Braun A et al.; An endonuclease from Escherichia coli which acts specificially upon UV-irradiated DNA (correndonuclease II) and is absent from the uvrA and uvrB mutants has been isolated and partially chacterized . The enzyme is present in normal amounts in the urvC mutant . It elutes from phosphocellulose at about 0.25 M potassium phosphate (pH 7.5) and passes through dialysis tubing . The enzyme binds tightly to UV-irradiated DNA but does not bind to unirradiated DNA . The enzyme incises irradiated DNA to the 5' side of a pyrimidine dimer and leaves a 5'-phosphoryl terminus which can be resealed with polynucleotide ligase . The Km of the enzyme is about 1.5 X 10(-8) M dimers . Endonucleolytic activity of the enzyme is inhibited by caffeine with a KI of about 10mM. Prep Biochem, 1975, 5(4), 319 - 32 Removal of unwanted proteins from cell extracts by means of antiserum; Lundqvist B et al.; The efficiency of removal of soluble proteins in cell-free bacterial extracts by means of antiserum from rabbits immunized with similar extracts was measured . Precipitation followed by Sephadex gel-chromatography was used . Up to 80% (exceptionally 90%) removal could be obtained . The method might be applied to enrichment for "foreign" cell-extract components, for example, viral products in virus infected cells . Tests for the specificity of the method are also presented. Pathol Microbiol (Basel), 1975, 42(3), 137 - 46 {Adherence of pathogenic Escherichia coli to epithelial cells isolated from the intestinal mucosa of the rabbit, inhibiting effect of hyperimmune bovine colostrum and of various carbohydrates (author's transl)}; Demierre G et al.; In order to study the mode of action of a bovine anti-Escherichia coli lactoserum (BLS), we have used a new test measuring the adherence of pathogenic E . coli on epithelial cells isolated from the small intestine of rabbit . A mixed suspension of E . coli and of epithelial cells is incubated for 15 min and the number of bacteria adhering to the cells counted under the microscope . The BLS at a concentration of 3.5 mg/ml IgG is able to reduce this number by a factor of 3-5 . After absorption of the BLS with formaldehyde-treated bacteria, this factor is smaller than 2 . At a concentration of 5 mg/ml, D-mannose and alpha-methylmannoside are as efficient inhibitors of adherence as BLS; at the same concentration, L-mannose is ineffective . The cultures of E . coli strongly agglutinating guinea pig erythrocytes, adhere to a larger extent to the epithelial cells . The last two observations confirm the important role played by fimbriae for the adhesive properties of E . coli . The presence of fimbrial antibodies would partially explain the inhibiting effect of BLS on adherence. Mol Gen Genet, 1975, 138(1), 65 - 9 Transience of the donor state in an Escherichia coli K12 strain carrying a repressed R factor; Broda P; De-repression of the plasmid R100 in Escherichia coli is essentially a transient phenomenon resulting in the transfer of several R factors to different recipient cells from a single donor cell. Mol Gen Genet, 1975, 138(1), 1 - 10 Preferential ribosomal RNA synthesis in the lysate of Escherichia coli; Muto A; The RNA synthesis in non-viscous lysates containing the intact folded chromosome and cytoplasm fractions prepared from Escherichia coli has been examined in vitro . The RNA synthesis not only by chain extension but also by new chain initiation occurs in this system . While the RNA synthesis by chain extension takes place on the chromosome fraction alone (Pettijohn et al., 1970), an addition of the cytoplasm fraction is necessary for the synthesis by new chain initiations (de novo synthesis) . Analyses of the in vitro synthesized RNA by hybridization-competition and by sucrose gradient centrifugation show that 16S and 23S ribosomal RNAs account for about 40% of the total RNA products . The cytoplasm fraction is required for the de novo synthesis of ribosomal RNA at high relative rate . Guanosine tetraphosphate (ppGpp) does not specifically inhibit ribosomal RNA synthesis in this system. Mol Gen Genet, 1975, 137(3), 263 - 8 The kinetics of derepression of prophage lambda following ultraviolet irradiation of lysogenic cells; Monk M et al.; Double lysogens for prophages lambda cI+ and lambda cI ind-ts-857 are induced only by the combined effects of ultraviolet (UV) irradiation and high temperature, not by either treatment alone (Sussman and Jacob, 1962) . We have followed the kinetics of inactivation of the cI+ repressor brought about by irradiation in asynchronously and synchronously growing cultures of B/r (lambda cI ind- ts-857) . Assays of the yield of phage released as a result of temporary thermal inactivation of the UV-resistant ind- ts-857 repressor at intervals after the irradiation accurately reflect the time course of UV-induced inactivation of the cI+ repressor . The results show that UV-induced derepression takes place in all cells of the population approximately 20 min after the irradiation whether the cells were growing asynchronously or synchronously . Hence UV induction of prophage lambda is not triggered at a particular stage in the cell cycle. Mol Gen Genet, 1975, 137(3), 249 - 61 Initiation of DNA replication in Escherichia coli . III . Genetic analysis of the dna mutant exhibiting rifampicin-sensitive resumption of replication; Saito T et al.; Temperature-sensitive mutants defective in the initiation of DNA replication are exposed to a non-permissive temperature to complete already initiated replication, and are transferred back to a permissive temperature . DNA synthesis can resume in the presence of rifampicin or rifampicin plus chloramphenicol in strain PC2 (dnaC2), but not in strain N167 (dna-167) . In the presence of chloramphenicol alone, however, DNA synthesis can resume in both strains (Hirage and Saito, 1973, 1974) . The double mutants carrying the dna-167 and dnaC2 mutations show the rifampicin-sensitive resumption of DNA replication as the dna-167 mutant . The rifampicin-sensitive character (designated as Rrr-) is closely linked with the temperature sensitivity of the dna-167 mutant in P1 transduction . The gene order is dna-167-tna-phoS-uncA-ilv . The Rrr- character does not correlate with the inactivation of the altered product of the mutated dna-167 gene at various temperatures in the double mutant carrying dna-167 and dnaC2 . Although dnaC2 strains show the Rrr+ phenotype, the dnaC2 strains received the ilv-dnaA region of the Ts+ revertants obtained from a dna-167 strain show the Rrr- phenotype . These results suggest that the dna-167 mutant has two mutations which are closely linked to each other, controlling the Rrr- phenotype and the temperature sensitivity, respectively. Mol Gen Genet, 1975, 137(3), 239 - 48 Initiation of DNA replication in Escherichia coli . II . Effect of rifampicin on the resumption of replication of F episome and chromosome upon the returning of dna mutants from a non-permissive to a permissive temperature; Hiraga S et al.; When E . coli F+ cells carrying the dna-167 or dnaC2 mutation, which causes the temperature-sensitive initiation of DNA replication, are exposed to a non-permissive temperature to stop the replication of chromosome and F factor, and then transferred back to a permissive temperature with the addition of chloramphenicol, one round of the chromosomal replication occurs, but further replication is inhibited . Under these conditions, F DNA replicates coincidentally with the initiation of the chromosomal replication in both strains . When rifampicin is added to the cells upon lowering of the temperature, the chromosome can not replicate in the F+ dna-167 strain, but can do so in the F+ dnaC2 strain . F DNA can replicate in both of the mutant strains under these conditions. Mol Gen Genet, 1975, 137(2), 151 - 60 Analysis of the ribosomes engaged in the synthesis of the outer membrane proteins of Escherichia coli; Randall LL et al.; The messenger RNAs for the outer membrane proteins in E . coli are more stable than the bulk of the messenger RNA s (Hirashima et al., 1973) . Polysomes, enriched in those containing stable mRNAs have been isolated following rifampicin treatment and have been shown to contain quantitatively the same complement of ribosomal protein as normal polysomes . There is one exception: ribosomal protein S1 is present in larger amounts in the polysomes containing stable messengers . However, there are grounds for believing this finding to be an artifact . It is concluded that the differences between outer membrane protein synthesis and bulk protein synthesis are not due to a difference in the ribosomes. Biochimie, 1975, 57(5), 545 - 50 {Quaternary structure of Escherichia coli polynucleotide phosphorylase: chemical characterization of form A}; Portier C; We had previously shown the existence of two classes of polynucleotide phosphorylases : Form A which is made of alpha chains and carries the catalytic sites ; and form B which is constituted of alpha chains and of beta chains . We performed some chemical analyses of form A (N-terminal sequence, amino acid composition, peptide mapping) which suggest that the alpha chains are all identical and moreover that they have no relationship with the beta chains . The latter do not therefore derive from a partial proteolytic degradation of the alpha chains and can therefore be considered as true subunits of the enzyme. Biochimie, 1975, 57(5), 539 - 44 {Analysis of a small quatity of polypeptides by two-dimensional electrophoresis: application to characterization of proteins}; Portier C; A new two-dimensional electrophoresis is described . The first electrophoresis is performed in a 10 p . cent gel (1 X 110 mm) in the presence of 7 M urea; the migration in the second dimension proceeds on a 20 p . cent polyacrylamide sheet (160 X 110 X 1 mm) in the presence of sodium dodecyl sulphate . This system resolves most of the polypeptides obtained by treating a very small amount (about 100 mug) of proteins with cyanogene bromide . Macromolecules can thus be quickly and easily characterized. Acta Microbiol Pol B, 1975, 7(2), 103 - 10 Some problems concerning the determination of different corrinoids by the plate method with Escherichia coli 113-3; Trojanowska K et al.; Biological activity of some vitamin B12 forms for Escherichia coli 113-3 and the effect of methionine on the assay of these compounds by E . coli 113-3 were studied . It was found that the coenzymatic form had the highest biological activity and that under experimental conditions methionine was an interfering factor in determination of the coenzymatic form and the methyl derivative of B12 only . Otherwise, metionine did not affect the determination of cyanocobalamin an hydroxycobalamin even when the methionine and vitamin B12 ratio was 32 000 : 1. Z Allg Mikrobiol, 1975, 15(4), 243 - 7 Unfolding of the chromosome of Escherichia coli after treatment with rifampicin; Dworsky P; Until recently it has been assumed that the factors being responsible for the condensation of the DNA in the nucleoid of Escherichia coli are destroyed by rifampicin because it has been impossible to obtain folded chromosomes from cells treated with this inhibitor . In this paper it is shown by viscosity and sedimentation measurements that unfolding of the DNA does not take place during the process of the cell lysis as it should be predicted from this assumption, but is occurring distinctly afterwards . Since the observed unfolding process is too slow to be caused simply by molecular movements it is concluded that it is brought about by the action of salts or detergents of the lysis medium . The structure of the nucleoid is still intact in vivo despite inhibition of RNA synthesis by rifampicin. Z Allg Mikrobiol, 1975, 15(4), 231 - 41 A mild method for the isolation of folded chromosomes from Escherichia coli; Dworsky P; Until now it has not been possible to obtain nuclear bodies from Escherichia coli after treatment with rifampicin . It was generally assumed that the cross-connections between the DNA double strands which are sensitive towards ribonuclease are destroyed under the influence of inhibitors of RNA synthesis like rifampicin . In this paper a new lysis procedure is described for preparing nuclear bodies from E . coli . These particles differ in some respects, especially in salt sensitivity from those prepared by earlier methods . Using the new lysis method it is also possible to obtain folded chromosomes from cells after treatment with rifampicin . These nuclear bodies can be destroyed by ribonuclease . Therefore, it has to be postulated that a fraction of RNA being sufficient to hold the chromosome in the folded shape is not susceptible to the action of rifampicin. Prep Biochem, 1975, 5(3), 257 - 80 Fragments of beta-galactosidase from Escherichia coli . Fragmentation, purification, characterization and in vitro complementation; Marinkovic DV et al.; Thermal fragmentation of the beta-galactosidase was studied in different buffer solutions and at different temperatures . Fragmentation of the subunits in small size polypeptides could be observed directly . The fragmentation proceeded in buffer solution, pH 7.0, at either 75 degrees C or 100 degrees C in the presence of sodium dodecyl sulfate . The elevated temperature appeared to accelerate this process . At 100 degrees C, pH 7.2, the fragmentation proceeded in the absence of sodium dodecyl sulfate, but in the presence of 8 M urea . Molecular weights, determined by sodium dodecyl sulfate disc gel electrophoresis were from 130,000 to about 20,000 . Multiple bands were observed . After dissociation was complete at 37 degrees C, the fragments were purified by ion-exchange column chromatography . Of the five fragments thus obtained, four were homogeneous by disc-gel electrophoresis . Molecular weight of the homogeneous fragments were found to be near 25,000 . The fifth comprised a mixture of four fragments having molecular weights from 29,000 to 72,000 . Two of the fragments were active as the alpha-donor in in vitro complementation with mutant M15, which contains a deletion in the alpha-region of the z gene. Pathol Microbiol (Basel), 1975, 42(2), 127 - 30 Inhibition of HBsAg immunologic reactivity and intestinal aerobic flora; Molinari V et al.; Cultures of human intestinal aerobic flora did not have any inhibiting action on the immunologic reactivity of hepatitis B antigen even after disruption of bacterial cells by freezing and thawing . This suggests that the inhibitor is elaborated by the human intestinal mucosa. Mol Gen Genet, 1975, 137(1), 85 - 88 Tetracycline-sensitive mutants of the F-like R factors R100 and R100-1; Foster TJ; The majority of tetracycline-sensitive (Tets) mutants of R100 and R100-1 are multisite (deletion) mutants . About 50% of these are also transfer-deficient, indicating that the Tetr locus is closely linked to the transfer genes . Tet(s) mutants with single-site lesions are also described. Mol Gen Genet, 1975, 137(1), 11 - 6 The regulatory nature of the phoB gene for alkaline phosphatase synthesis in Escherichia coli; Yagil E et al.; Quantitative measurements of alkaline phosphatase activity in various merozygotic combinations and electrophoretic analyses of periplasmic proteins derepressed by phosphate-starvation show that phoB is a positive regulatory gene. Mol Gen Genet, 1975, 137(1), 1 - 10 Conjugation in Escherichia coli: a study of recombination and the fate of donor DNA at the level of the zygote; Bergmans HE et al.; We have developed an experimental system for studying concomitantly the fate of the donor DNA and the process of recombination after conjugation in Escherichia coli . We used a set of Hfr and F-strains carrying complementing lacZ mutations . Expression of the lacZ allele on the chromosomal fragment derived from the donor results in the formation of heat sensitive beta-galactosidase by complementation . By intragenic recombination between the two lacZ mutations a lacZ+ gene may be formed, and wild type beta-galactosidase will be synthesized subsequently . So the assay of heat sensitive and wild type beta-galactosidase enabled us to follow respectively the fate of the donor DNA and the recombination process . Using various recombination deficient recipient strains, we found that the donor DNA is progressively inactivated in recA, rec-34 and recH recipients, although the initial rate of expression is equivalent to that in a Rec+ recipient; no significant recombination was observed . In Rec+, recB or recG recipients there was no inactivation and recombination occurred . The kinetics of recombinant formation in the recB strain seems to differ from the wild type; in a recG recipient the recombination activity is significant, but lower than in the wild type recipient. Cytobios, 1975, 12(45), 19 - 29 Galactose-specific messenger ribonucleic acid contents in Escherichia coli: effect of inducer, gene dosage and galactose genotype; Gosden JR; Galactose specific mRNA (gal-mRNA) and galactokinase were measured in strains of E.coli with varying numbers of copies of the galactose operon . While the fucose induction the amount of gal mRNA has been found to be proportional to the content of galactokinase and to the gene frequency, with galactose induction this was not the case . It is suggested that this is a result of the metabolism of galactose leading to catabolite repression . The amounts of gal-mRNA and galactokinase were also measured in a series of polar mutants . With increasing polarity, there was a greater effect on enzyme content than on gal-mRNA . This suggests that the effect of polarity on RNA is the result of degradation after synthesis rather than prevention of transcription . A method of correlating hybridisation data with the genetic map is described. Neoplasma, 1975, 22(2), 147 - 56 Comparison of the effect of nalidixic acid and thymine deprivation on excision repair in Escherichia coli; Masek F et al.; There is a difference in the extent of inhibition of thymine dimers (TT) excision in ultravioley (UV) irradiated cells of E . coli after preirradiation depression of protein and DNA syntheses induced by a simultaneous deprivation of essential amino acids (AA-) and thymine(T-) or by deprivation of essential amino acids and addition of nalidixie acid (NAL+) . This difference has been noted in both E . coli B/r Her+ and E . coli K12 SR20 uvr+ cells . Depression of DNA synthesis with the aid of malidixic acid as exogenous agent will inhibit TT excision to a lesser degree than depression of DNA synthesis by thymine starvation . The extent of TT excision has no appreciable influence on restoration of the sedimentation profile of newly synthesized DNA nor again on UV resistance of cells in conditions of dark repair . At the time when there are TT still present in DNA, the DNA molecule, having the size of the molecule of unirradiated cells, will become synthesized. Microbios, 1975, 12(50), 179 - 97 Investigation into pyruvate kinases from Escherichia coli K-12 grown under aerobic and anaerobic conditions; Gibriel AY et al.; Two forms of anaerobic Escherichia coli K-12 pyruvate kinase (EC 2.7.1.40) were separated by ammonium sulphate fractionations . Pyruvate kinases I is allosteric and pyruvate kinase II is non-allosteric to phosphoenolpyruvate . The addition of 1 mM FDP reversed the allostery to normal Michaelis-Menten kinetics . AMP had no effect, whereas 8 mM ATP completely inhibited the enzyme . The enzyme showed normal kinetics with ADP as substrate . Mg2+ and Mn2+ stimulated whereas Cu2+ severely inhibited the enzyme, which could be reversed by the addition of 1 mM FDP . Citrate, alpha-ketoglutarate, succinate, fumarate and alanine inhibited the enzyme, whereas phenylalanine had no effect . The allosteric pyruvate kinase from aerobic cultures was not only activated by FDP, but also by AMP . FDP changed Km and Vmax, whereas AMP influenced only the Km . During aerobic-anaerobic transition, pyruvate kinase synthesis increases and reaches a maximum under anaerobic conditions . The degree of FDP activation remains constant, but AMP activation is lost during transition . Aerobic cultures of E . coli K-12 grown on gluconeogenic substrates exhibited pyruvate kinase II activity (non-allosteric), which was stimulated by FDP and by AMP . It has been suggested that E . coli may have two types of pyruvate kinase II depending on the substrate and two types of pyruvate kinase I depending on oxygen tension in the medium. Chemotherapy, 1975, 21(3-4), 131 - 45 Kinetics and mechanisms of action of 'folate synthesis inhibitors', alone or in combination, on Escherichia coli . III . Pyrimethamine, trimethoprim and sulfamethoxazole; Seydel JK et al.; The inhibitory activity of pyrimethamine (PMA) is 1/290 of the activity of trimethoprim (TMP) against E . coli as evaluated from a plot of C.ko/ko-kapp VS . C . Even at high concentrations the effect of PMA in contrast to TMP seems to be cateriostatic . Combinations of TMP and PMA reveal an additive effect . In PMA-treated cultures, the slope of the logarithmic growth curve decreases after an initial inhibited growth, and a second steady state is established . This second steady state has a different reason than the one observed in TMP-treated cultures; whereas the second phase in TMP-inhibited cultures depends on the number of germs, in the case of PMA it depends on the number of generations . Using prewashed cell cultures, it was shown that there is no influence on the two steady states in PMA-inhibited cultures; for TMP, however, it was shown that the presence of the first phase is due to an antagonist excreted into the culture medium . These observations hint at differences in the mode of action of TMP and PMA in addition to differences in the affinity to the target enzyme dihydrofolate reductase . Combination of PMA with sulfamethoxazole (SMZ) at concentrations where both drugs are acting only bacteriostatically leads to effects considerably greater than would be expected from simple additivity . The kill rate observed is the same as observed for TMP/SMZ combinations despite of the considerable lower activity of PMA and SMZ . The results support the assumption that it might be possible to select drug combinations considering the best pharmacokinetical fit and not necessarily the most effective drugs in the series studied. Acta Microbiol Acad Sci Hung, 1975, 22(3), 309 - 14 The mutagenic effect of pesticides on Escherichia coli WP2 try; Nagy Z et al.; Thirty pesticides commercially available in Hungary and three well-known chemical mutagens were applied to agar plate cultures of her+ and her- derivatives of Escherichia coli WP2 try- strain . After incubation, the plates were examined for a relative increase in reverse mutation number . N-Trichloro methylthio-1,2,3,6-tetrahydrophthalimide, dimethyl-3,2-dichlorovinyl-phosphate and N-trichloro methylthiophyhalamide proved to have definite mutagenic activity. Acta Microbiol Acad Sci Hung, 1975, 22(3), 249 - 52 Effect of hypothermia and endotoxin on phagocytosis; Sipka S et al.; Experiments with colloidal 198Au indicated that gold clearance highly decreased in rabbits cooled to 29-30 degrees C . The capacity of storing colloidal gold decreased especially in the spleen and liver . Endotoxin reduced the gold clearance in normothermic rabbits; the decrease was more marked in hypothermic animals. Q J Med, 1975 Jan, 44(173), 65 - 77 Acute reversible renal failure in patients with acute cholecystitis and cholangitis; Burden RP et al.; Although acute renal failure is a well recognized complication of several extra-hepatic biliary tract diseases especially biliary tract surgery in the presence of obstructive jaundice, there is little information concerning renal failure in acute cholecystitis . Renal function was assessed in 14 patients with acute cholecystitis and two with acute cholangitis . Six patients had no evidence of renal impairment, four had modest elevations of plasma urea and creatinine concentrations and six had acute reversible renal failure of whom three required peritoneal dialysis . Only one patient was hypovolaemic and in the remainder there was evidence that intravasular coagulation was responsible for the renal failure . It is suggested that bacteraemia was the initiating factor . The therapeutic implications of these findings are discussed. Int Urol Nephrol, 1975, 7(1), 7 - 12 Pyleonphritis as a side effect of hormonal contraception: an experimental research; Pytel Yu A et al.; In animal experiments it was proved that contraceptives may cause considerable renal changes . It is necessary to call gynecologists' attention to possible side effects; the contrapaceptives are contra-indicated in chronic pyelonephritis. Biochimie, 1975, 57(3), 271 - 6 Sequence diagrams and the presentation of structural and evolutionary relationships among proteins; Thomas BR; Protein sequences mapped on two-dimensional diagrams show characteristic patterns that should be of value in visualising sequence information and in distinguishing simpler structures . A convenient map form for comparative purposes is the alpha-helix diagram with aminoacid distribution analogous to the surface of an alpha-helix oriented so that an alpha-helix structure corresponds on the diagram to a vertical band 3.6 residues wide . The sequence diagram for an alpha-keratin, high-sulphur protein suggests a new form of polypeptide helix based on a repeating unit of five which may be an important component of alpha-keratin fibres. Biochimie, 1975, 57(1), 1 - 8 {Individuality of mannonate and altronate hydro-lyases in Escherichia coli K 12}; Robert-Baudouy JM et al.; In Escherichia coli, mannonic and altronic hydrolyases act, respectively, on mannonate, the intermediate aldonate of the glucuronate branch, and on altronate the intermediate aldonate of the galacturonate branch of the hexuronate pathway, yielding 2-keto-3-deoxy-gluconate . Our results demonstrate that the two hydrolyases are two distinct proteins . First, each hydrolyase shows a different induction pattern . In addition, separate constitutive mutants for either hydrolyase have been obtained . Second, single mutants negatively affected for one of the activities but not the other have been isolated in each case . Third, comparative heat inactivation of both activities at 59 degrees C shows mannonic hydrolyase to be clearly more thermosensitive than altronic hydrolyase . Furthermore the two enzymes also react differently to various effectors . Fourth, the two enzymes could be resolved on a DEAE cellulose column into two neighbouring but distinct peaks of activity, and a further purification yielded two pure hydrolyase fractions each being devoid of the activity of the other. Scand J Immunol, 1975, 4(2), 139 - 43 Genetic control of B-cell responses . I . Selective unresponsiveness to lipopolysaccharide; Coutinho A et al.; Spleen cells from C3H/HeJ mice fail to develop both proliferative responses and increased polyclonal antibody secretion in the presence of concentrations of the B-cell mitogen lipopolysaccharide that are optimal for the induction of B-cell responses in conventional strains . This unresponsiveness is selective for lipopolysaccharide, since C3H/HeJ spleen cells respond normally to two other polyclonal B-cell activators-dextran-sulphate and purified protein derivative of tuberculin . These findings are interpreted as indicating a selective defect in the B-cell subpopulation that responds to lipopolysaccharides in conventional strains. Folia Microbiol (Praha), 1975, 20(3), 264 - 71 Novel approaches to the mode of action of colicins; Smarda J; According to the theory of Fredericq (1949) and Nomura (1964), colicins are attached by specific receptor sites in the cell walls of sensitive bacteria, which mediate their inhibitive effects . During last years, a great variety of experimental data have been accumulated, some of which cannot be easily interpreted in terms of this theory . There exist considerable discrepancies concerning the chemical nature and molecular weight of isolated receptors . The attachment of a colicin onto its receptor need not be irreversible . The inhibition of numerous membrane-associated functions in colicin-tolerant mutants suggests their pleiotropic deletion nature . The difference between colicin resistance and colicin tolerance does not seem to be clear-cut . Cells of stable L-forms of protoplast type, completely devoid of their walls, retain in most cases the same patterns of sensitivity to colicins as rods of the same strains . Experimental changes in the relationship between the cell wall and the cytoplasmic membrane decrease colicin sensitivity of the cells . Colicin E3 has been found to be a specific endoribonuclease, able to cleave a terminal fragment from the 16 S rRNA also in isolated ribosomes in vitro: not only in ribosomes from sensitive bacteria, but also in those from resistant ones and from eukaryotic cells . A destabilization of the DNA helix was induced by colicin E2 in vitro as in vivo . It seems that there exist two distinct types of colicin receptors with different functions: those in the cell wall, and those in the cytoplasmic membrane . Only the contact of colicins with the latter ones is biologically effective and starts both stages of their inhibitive effect: the reversible and the irreversible ones. Folia Microbiol (Praha), 1975, 20(3), 251 - 60 The in vitro and in vivo effects of carrageenin on humoral and cellular factors of natural resistance; Miler I et al.; The inhibitory effect of carrageenin, a sulfated algal polygalactose, on humoral factors of natural resistance is discussed . In dependence on dose and time, the influence of non-specific and specific bacteriolysis, on the in vitro and in vivo opsonic activity and on the course of infection was studied. Folia Microbiol (Praha), 1975, 20(3), 224 - 30 Penicillinamidohydrolase in Escherichia coli . I . Substrate specificity; Vojtisek V et al.; Substrate specificity of the bacterial penicillinamidohydrolase (penicillinacylase, EC 3.5.1.11) from Escherichia coli was determined by measuring initial rates of enzyme hydrolysis of different substrates within zero order kinetics . Some N-phenylacetyl derivatives of amino acids and amides of phenylacetic acid and phenoxyacetic acid of different substituted amides of these acids or amides, structurally and chemically similar to these compounds, served as substrates . Significant differences in ratios of initial rates of the enzyme hydrolysis of different substrates were found using a toluenized suspension of bacterial cells or a crude enzyme preparation, in spite of the fact that the enzyme is localized between the cell wall and cytoplasmic membrane, in the so-called periplasmic space . N-phenylacetyl derivatives are the most rapidly hydrolyzed substrates . Beta-phenylpropionamide and 4-phenylbutyramide were not utilized as substrates . The substrate specificity of the enzyme is discussed with respect to a possible use of certain colourless compounds as substrates, hydrolysis of which yields chromophor products suitable for a simple and rapid assay of the enzyme activity. Biomater Med Devices Artif Organs, 1975, 3(1), 1 - 24 Comparative evaluation of artificial ventricles in the United States; Peters JL et al.; A cooperative, comparative evaluation of nine artificial ventricles was performed on two standardized mock circulations . The ventricles included five air-driven diaphragm types, three sack types and a mechanically driven type . The slopes of the ventricular output curves varied from 0.04 to 0.88 at 0 to 5 Torr filling pressure and the maximum ventricular output varied from 3.8 to 11.9 liters/min at 100 Torr outflow pressure . All ventricles had decreased output with increased outflow pressures (70 to 130 Torr) . Hemolysis index ratio (HI test/HI std) for HI std equals 0.024 plus or minus .005 (plus or minus 1 SD) g/100 liters (N equals 12), was +21.5 and +6.9 for a Dacron cloth and fibril heart, respectively, +2.0 to +2.86 for three sack ventricles, and +3.2 for a smooth diaphragm ventricle . The mechanical ventricle with a sinusoidal driving waveform and smooth surface had the lowest hemolysis, HI equals 0.008 plus or minus 0.003 (plus or minus 1 SD) (N equals 6) . Sack ventricles caused marked hemolysis if the walls touched during systole . Ventricular dimensions varied: weight 116 to 700 g, length 9.2 to 18.7 cm, and volume 235 to 430 ml . Performance data was returned to each individual laboratory which resulted in modification of ventricular design in at least three instances . Comparative, standardized testing of artificial ventricles may shorten development time and provide performance criteria for application in man. Biokhimiia, 1975 Jan-Feb, 40(1), 83 - 8 {Binding of ribosomal RNAs with ribosomal proteins covalently bound to polymer carriers}; Spiridonova VA et al.; Conditions for covalent binding of ribosome proteins from Escherichia coli with insoluble polymers are found . A number of polymer carriers and several methods of protein binding to them were tested, the best one being the fixation of ribosome proteins on cyanogen bromide-activated Sepharose . Binding is studied with fixed on the polymer total 30S and 50S proteins, with individual S7 and S20 proteins, 16S and 23S RNAs in conditions optimal for the reconstruction of 30S subunits in vitro . It is found that at least some of ribosome proteins, being bound with polymer carrier, retain the ability to recognize their specific sites on RNA. Biokhimiia, 1975 Jan-Feb, 40(1), 187 - 91 {Ribosome stability of Escherichia coli cells in amino acid starvation}; Rabinovich PM et al.; The dissociation of ribosomes from two isogenic pairs of Escherichia coli strains was studied during exponential growth, under amino acid starvation and subsequent chloramphenicol treatment . There were no significant differences in Mg2+-dependent dissociation of ribosomes from exponentially growing rel+ and rel- minus strains . The differences in dissociation of the ribosomes from rel+ and rel- minus cells were observed only upon amino acid starvation of these cultures . The dissociation of ribosomes from starved rel+ cells was more complete . After chloramphenicol treatment isolated ribosomes were more resistant to dissociation into subunits . Alterations of dissociation of the ribosomes in vitro correlated both with the amount of polysomes and the level of RNA synthesis in cells . It is proposed that rRNA synthesis in bacteria depends on the ratio of programmed and deprogrammed ribosomes. Ateneo Parmense Acta Biomed, 1975 Jan-Apr, 46(1-2), 45 - 52 {Treatment of inflammatory complications of permanent implanted pacemakers}; Medici D et al.; The Authors report an experience of 165 patients who underwent to implantation of artificial pacemaker from January 1973 to December 1974 and report 16 cases of infection . They consider many surgical and biologic factors that can have caused uprinsing of infection . The Authors report the therapeutic treatment the patients underwent and conclude that the best treatment is the implantation, to another seat, of new pacemaker. Scand J Immunol, 1975, 4(1), 89 - 94 Mechanism of B-cell activation and paralysis by thymus-independent antigens . Additive effects between NNP-LPS and LPS in the specific response to the hapten; Coutinho A et al.; Normal spleen cells showed a bell-shaped dose response profile when stimulated in vitro with the thymus-independent antigen (4-hydroxy-3,5-dinitrophenyl)acetyl (NNP)-lipopolysaccharide (LPS) with regard to the development of high-avidity plaque-forming cells to NNP . The addition of suboptimal concentrations of LPS to cultures stimulated by suboptimal concentrations of NNP-LPS resulted in optimal induction of B cells in that affinity fraction . Addition of LPS to cultures optimally stimulated by NNP-LPS resulted in paralysis of the specific cells . These results are interpreted in terms of the additive effects between the mitogenicity of LPS and the mitogenicity of NNP-LPS, the latter being selectively focused on the specific cells, thus providing further evidence for the 'one nonspecific signal' hypothesis for immune activation of B cells. Acta Biochim Pol, 1975, 22(1), 87 - 98 Preparative enzymic synthesis of nucleoside-5'-phosphates; Giziewicz J et al.; 1 . Wheat shoot phosphotransferase has been employed, with p-nitrophenylphosphate as a phosphate donor, to specifically phosphorylate the 5'-position of a variety of nucleosides and nucleoside analogues . The specificity of the enzyme towards the 5'-position of pentose nucleosides is testified to by the complete resistance to phosphorylation of 5'-O-methylcytidine . 2 . With the use of ion-exchange chromatography, the foregoing procedure has been applied to the large-scale preparation of nucleoside-5'-phosphates with overall yields of the order of 80-90% . Quantitative recovery of unreacted nucleoside makes it possible to use this method without risk of losses either on a small or large scale with rare nucleosides . It is also applicable to acid- and alkali-labile nucleosides which cannot readily be phosphorylated by chemical procedures . 3 . The wheat shoot phosphotransferase also phosphorylated a galactopyranosyl nucleoside, as well as such derivatives as 1-(beta-hydroxyethyl)cytosine and 5-(beta-hydroxyethyl)uracil, showing that the enzyme does not have an absolute requirement for a 5-membered sugar ring, but rather for the presence of a primary hydroxyl group . 4 . The phosphorylated derivatives of galactopyranosyluracil, and of both hydroxyethyl pyrimidines, were resistant to 5'-nucleotidase . E . coli alkaline phosphatase converted all three nucleotides quantitatively to the starting compounds . 5 . A synthesis of 1-(beta-hydroxyethyl)cytosine is described. Nucleic Acids Res, 1975 Jan, 2(1), 43 - 60 Enzymatic multiplication of a chemically synthesized DNA fragment; Olson K et al.; A synthetic DNA fragment of 19 residues was enlarged by the enzymatic addition of deoxyadenylate residues to its 3'-end with calf thymus terminal deoxynucleotidyl transferase . The 3'-terminus of this elongated DNA strand was blocked with 2', 3'-dideoxyadenylate to prevent hydrolysis by the 3'-exonuclease function of E . coli DNA polymerase I . This elongated and 3'-blocked fragment was annealed to an oligomeric primer and used as a template for the synthesis of a complementary copy of the synthetic 19-mer . The product of such a repair synthesis was separated by gel filtration and analyzed by nearest neighbor techniques . All template strands were copied with complete repair in over 90% of the chains . Facile recovery of the elongated template by virtue of its size permitted repetition of the copy process, thus allowing accumulation of the desired strand. Nucleic Acids Res, 1975 Jan, 2(1), 113 - 9 Accessibility of chromatin to DNA polymerase I and location of the F1 histone; Saffhill R et al.; The effect of prebound poly-L-lysine upon the template activity of DNA, chromatin and F1 histone-depleted chromatin for E . coli DNA polymerase I has been investigated . Measurements have been made in the absence and presence of 0.1M NaCl . From the results we conclude that only ca 60% of the polylysine-accessible DNA, i.e . 22% of the total DNA of the chromatin, is accessible to the DNA polymerase I and that ca . 30% of the polylysine-accessible DNA, i.e . 11% of the total DNA, is associated with the F1 histone. Mol Biol, 1975 Jan, 8(4), 410 - 8 An x-ray diffraction study of ribosome structure; Dolgov AD et al.; Dense gels of E . coli 70 S ribosomes, their 50 S subunits, CM-like particles, RNP strands and their fragments, 38 S particles obtained from RNP strand folding upon addition of Mg2+ ions, and of unoriented salt-free and free rRNA sodium and magnesium salts were studied by X-ray diffraction . It was shown that under dense gel conditions RNA molecules contained in ribosomes unfolded by desalting, like all other particles considered here, have helical regions . Under these conditions free desalted RNA has no helical regions . Experimental data on X-ray scattering at medium angles were compared with the diffraction curves calculated for homogeneous prolate and oblate ellipsoids, for various ellipsoids containing a dense region or an internal cavity, and for ellipsoids containing internal periodic regions . The results indicate that the internal structure of the 50 S ribosome is periodic, i . e., its components form a periodic lattice . The lattice spacings are approximately 42 and 28 A with a 0.8g/g dry weight sample water content . When the 50 S particle water content drops below 0.2 g/g dry weight the periodic structure is disrupted . This disruption is reversible . It was shown that CM-like particles at high ionic strenght (2 M LiCl) have approximately the same internal periodicity as the 50 S particles, but in contrast they lose this periodicity at low ionic strength (10-2M tris-HCl and 5-10-3 M MgCl2). In Vitro, 1975 Jan-Feb, 11(1), 41 - 5 Hydrolysis of oligopeptides by sera used in cell and tissue culture; Jones JE et al.; Sera commonly used in cell and tissue culture as medium supplements possess high peptidase activity . Pligopeptides incubated with 1% serum are rapidly hydrolyzed to intermediate length peptides and the constituent amino acids . Hydrolysis of lysine peptides is difficult to verify by a quantitative ninhydrin procedure because of reaction of the lysine epsi-lon-amino group and serum components with ninhydrin . Attempts to evaluate oligopeptides as sole sources of indispensable amino acids for cultured mammalian cells are of doubtful value when serum is used as a medium supplement. Enzyme, 1975, 20(3), 188 - 92 Immobilized L-asparginase embedded in fibrin polymer; Inada Y et al.; Immobilized asparaginase was prepared by embedding asparaginase (which is effective for remission in children with leukemia) into fibrin polymer formed by fibrinogen-fibrin conversion in the presence of thrombin . The immobilized asparaginase film did not dissolve in 6 mol/1 urea, suggesting that blood coagulation factor XIII participates in the cross-linking between fibrins and between fibrin and asparaginase. Vopr Virusol, 1975 Jan-Feb, (1), 9 - 14 {Biological and physicochemical properties of virus PBV-1, isolated from Penicillium brevi compactum}; Chaplygina NM et al.; High infectivity of PBV-1 virus for different strains of E . coli has been demonstrated . Sizes of the virus particle are; head diameter 513 angstrom, length of the process 1500 angstrom, diameter of the process 60 angstrom . The buoyant density of the virus in cesium chloride density gradient is 1.49 g/cm3, in cesium sulphate-1.39 g/cm3, the sedimentation constant of the virus particle is 380S; molecular weight is 52.8 plus or minus 1.9 times 10-6 daltons . The PBV-1 virus contains double-stranded DNA with the melting temperature in 1 SSC (0.15 M NaCl plus 0.0015 M sodium citrate, pH 7.0) and in 0.1 SSC-88.5 degrees C, respectively . The buoyant density of DNA in cesium chloride gradient is 1.7058 g/cm3 and in cesium sulphate 1.424 g/cm3 . The content of GC-pairs calculated by the melting temperature is 46.5% and by the buoyant density 46.7% . On the basis of DNA sedimentation constant value (30S) the average molecular weight of DNA has been calculated to be 23.7 times 10-6 daltons. Res Commun Chem Pathol Pharmacol, 1975 Jan, 10(1), 127 - 48 The effects of plumbous ion on protein biosynthesis in reticulocytes; Farkas WR; Plumbous ion a potent inhibitor of hemoglobin synthesis by reticulocytes in vivo, is not as effective in inhibiting in vitro globin synthesizing systems prepared from these cells . The reticulocyte is considerably more sensitive to Pb2+ than are leukemic leukocytes, HeLa cells or bacteria . In fact, protein synthesis in leukemic leukocytes is actually stimulated by Pb2+ . The synthesis of non-heme protein as well as hemoglobin is inhibited by Pb2+ in reticulocytes and the synthesis of alpha chains is inhibited to a greater degree tcids into reticulocytes . All of these observations are consistent with the biosynthesis of heme rather than any of the steps in protein biosynthesis being the locus for inhibition of hemoglobin synthesis by low levels of plumbous ion . Also, there is marked biological variations in the susceptibilities of reticulocytes from different rabbits to Pb2+. Can J Biochem, 1975 Jan, 53(1), 1 - 10 Selective labelling ot the methyl carboxylate substituents found in the anticodon sequences of some species of yeast transfer RNA; Kennedy TD et al.; (1) By incubation in 0.1 M NaOH for 10 min at room temperature, it is possible to "saponify" some of the methyl carboxylate linkages in bulk yeast tRNA . By incubation with S-adenosyl(Me-14-C)methionine and either homologous (yeast) or heterologous (wheat-embryo) enzymes, it is then possible to "re-esterify" the "saponified" tRNA and thereby effect selective labelling at 5-carboxymethyluridine (Me-14-C)methyl ester residues . (2) There is also selective labelling at 2-thio-5-carboxymethyluridine (Me-14-C)methyl ester residues when "saponified" yeast tRNA is incubated with S-adenosyl(Me-14-C)methionine and homologous (but not heterologous) enzymes . (3) When selectively labelled yeast tRNA is hydrolyzed by RNase T-1, both 5-carboxymethyluridine (Me-14-C)methyl ester and its 2-thio-analogue are released as part of large oligonucleotides, each of which contains roughly 10 nucleotide residues . (4) There are at least three, and possibly four (Me-14-C)methyl ester-containing oligonucleotides released by RNase T-1 digestion of selectively labelled "saponified" yeast tRNA . A comparison of the chromatographic properties of the different (Me-14-C)oligonucleotides suggests that the same 5-carboxymethyluridine residues are probably targets for both homologous and heterologous enzymes . (5) The properties of the selectively labelled oligonucleotides are consistent with the view that some of them probably are derived from yeast tRNA-3-Glu, tRNA-2-Lys, and tRNA-3-Arg, all of which are known to contain 5-carboxymethyl methyl esters as part of their anticodon sequences. Avian Dis, 1975 Jan-Mar, 19(1), 1 - 5 A quantitative study of the effect of endotoxin on embryonating chicken eggs; DaMassa AJ et al.; A quantitative study of the effect of endotoxin on embryonating chicken eggs revealed the importance of several variables . In the study, the chorioallanotic membrane was detached (i.e.,dropped) from the eggshell membrane on the 9th and 11th incubation days . Various doses of endotoxin in various amounts of diluent were applied on the dropped membrane on the 11th day . Embryo deaths were greater when the membrane was dropped on the 11th day . Within the limits of our trial, the variables were, in decreasing order of significance: 1) the day the membrane was dropped; 2) the amount of endotoxin applied; and 3) an interaction between 1 and 2 . The volume of diluent had no significant effect on mortality . The importance of these variables is discussed with reference to the design of additional experiments with endotoxin. Res Vet Sci, 1975 Jan, 18(1), 36 - 40 The effects of Escherichia coli endotoxin on the concentrations of mineral elements in the plasma of the domestic fowl; Butler EJ et al.; The intravenous injection of E coli endotoxin (serogroup 0111 : B4) into eight to nine week old disease-free fowls (0-025-3-0 mg/kg) produced successive falls in the plasma potassium and calcium levels during the 9 h following the injection . This change in the potassium concentration was accompanied by a slight rise in that of sodium, and in some cases a slight rise in that of sodium, and in some cases a slight reduction in the magnesium concentration was detected when that of calcium was reduced . No effect was observed 24 h after the injection . The metal-binding properties of endotoxin, its affinity for membranes and its effect on the secretion of adrenocortical hormones may be involved in the production of these responses . Their pathophysiological significance is also discussed. Res Vet Sci, 1975 Jan, 18(1), 107 - 8 The effect of bithionol sulphoxide on Echinococcus granulosus and Taenia hydatigena infections in dogs; Bywater RJ; Double Thiry-Vella loops in calves were used to show that when heat stable E coli enterotoxin was in contact with only one of the loops, a net increase in water secretion occured in both . It was concluded that either enterotoxin itself or a mediator substance was absorbed and acted via the systemic circulation. Proc Natl Acad Sci U S A, 1975 Jan, 72(1), 6 - 10 Specialized transducing phages for ribosomal protein genes of Escherichia coli; Jaskunas SR et al.; Specialized lambda transducing phages have been isolated carrying approximately half the ribosomal protein genes of E . coli . These phages carry regions of the bacterial chromosome between aroE and fus . The ribosomal protein genes on these phages have been identified by the stimulation of ribosomal protein synthesis in ultraviolet-irradiated bacteria following infection by the transducing phage, and by the in vitro synthesis of ribosomal proteins in a DNA-dependent protein synthesizing system . The results indicate lambdadspcl probably carries at least 22 ribosomal protein genes and lambdadspc2 at least 26 genes . All these genes are clustered between trkA and strA . At least 13 of them have not been previously mapped. Proc Natl Acad Sci U S A, 1975 Jan, 72(1), 405 - 8 Regulation of proline catabolism by leucyl,phenylalanyl-tRNA-protein transferase; Deutch CE et al.; A mutant of Escherichia coli lacking leucyl,phenylalanyl-tRNA:protein leucyltransferase, EC 2.3.2.6) exhibited several abnormal growth characteristics relative to the wild type or a revertant when grown with glycerol as a carbon source . All three strains were auxotrophic for proline . The mutant required higher levels of this amino acid than did the other strains to attain a normal growth yield and metabolized exogenous {14C}proline more rapidly . The greater rate of proline utilization was associated with a 4-fold increase in specific activity of proline oxidase . When glucose rather than glycerol was employed as a carbon source, proline oxidase activity was reduced by catabolite repression and the growth ccharacteristics of the mutant were similar to those of the parental and revertant strains . These results suggest that the mutant growth phenotype is due to an altered rate of proline catabolism and constitue evidence for regulation of a specific metabolic pathway by leucyl,phenylalanyl-tRNA-protein transferase. Proc Natl Acad Sci U S A, 1975 Jan, 72(1), 314 - 7 A new chemical procedure for 32P-labeling of ribonucleic acids at their 5'-ends after isolation; Rapaport E et al.; A new technique, which utilizes the chemical reaction between {32P}diimidazolidate of orthophosphate and the cetyltrimethylammonium salt of high-molecular-weight RNA in nonaqueous dimethyl formamide, has been developed for the 32P-labeling of RNAs after isolation . The radioactive label of high specific activity is introduced onto a phosphorylated 5'-end of the RNA and renders it suitable for 5'-terminal group analysis . When the labeling reaction was applied to the 70S RNA of avian myeloblastosis virus, a labeled 35S RNA was isolated on sucrose-dimethyl sulfoxide gradients without apparent degradation. Proc Natl Acad Sci U S A, 1975 Jan, 72(1), 194 - 9 Chromatin as a template for RNA synthesis in vitro; Groner Y et al.; RNA transcribed in vitro from myeloblast chromatin by exogenously added RNA polymerase B predominantly consists of short chains that remain in hybrid structure with the template; the remainder of the product is free RNA of heterogeneous size . Addition of polyanions during synthesis caused an increase in the size and amount of free RNA with a concomitant decrease in the proportion of small RNA . The large molecular weight RNA is derived from the short RNA chains, which are synthesized de novo during the reaction in vitro . The effect of polyanions on the size and nature of the product may be related to structural changes induced in the template rather than to an inhibition of nuclease activity. J Immunol, 1975 Jan, 114(1 Pt 2), 452 - 8 Thymic regeneration after lethal irradiation evidence for an intra-thymic radioresistant T cell precursor; Kadish JL et al.; The data presented indicate the existence of a significant pool of radioresistant stem cells which are capable of partially restoring the thymus of heavily irradiated mice . 3-H-TdR incorporation by the thymus of lethally irradiated mice begins 48 to 72 hr after irradiation and increases throughout the next 8 days . By the 9th day after 760 rads, typical corticomedullary architecture has been restored . 890 rads markedly suppressed, but did not totally eliminate this regeneration . Injection of large numbers of syngeneic bone marrow cells immediately after irradiation was without effect on the rate or extent of regeneration . Mice whose bone marrow and spleen were shielded from irradiation showed an identical amount of thymic regeneration as those receiving total body irradiation indicating that the precursor cell pool responsible for the early post irradiation phase of thymic regeneration is most likely an intrathymic population . The cells repopulating the thymus were morphologically indistinguishable from normal thymocytes and were susceptible to cytotoxic antisera against the thymic differentiation antigens Thy-1, TL, LyA2 and LyC2. J Immunol, 1975 Jan, 114(1 Pt 2), 365 - 70 Effects of concanavalin A on the in vitro responses of mouse spleen cells to T-dependent and T-independent antigens; Jacobs DM; ?The stimulatory and inhibitory effects of concanavalin A (Con A) on the in vitro primary immune responses to a T-dependent antigen, sheep erythrocytes (SRBC) and a T-independent antigen, TNP-lipopolysaccharide (TNP-LPS) have been studied . Inhibition of the response to both antigens was optimal when 2 mug Con A were added at the initiation of the culture period . The response to SRBC was considerably enhanced by the addition of Con A 24 hr later . In contrast, this late addition did not stimulate the TNP-LPS response and often inhibited it . Inhibition of the TNP-LPS response required the participation of T cells since it was not observed in cells from adult thymectomized irradiated bone marrow-reconstituted (ATXBM) mice . The response to TNP-LPS was somewhat enhanced in ATXBM cells, but the degree of enhancement was strikingly less than that observed for SRBC . LPS per se did not block the stimulatory effect of Con A on the SRBC response, and was observed to act synergistically with this lectin . None of the Con A effects observed required the participation of adherent cells . These observations are consistent with a model in which different subpopulations of T cells are responsible for the inhibitory and stimulatory effects . They further suggest that the Con A inhibitory activity acts via a T cell to inhibit directly the B cell response to antigen. J Immunol, 1975 Jan, 114(1 Pt 2), 360 - 4 Stimulation of a T-independent primary anti-hapten response in vitro by TNP-lipopolysaccharide (TNP-LPS); Jacobs DM et al.; The trinitrophenyl hapten (TNP) has been covalently conjugated to bacterial lipopolysaccharides (LPS) to give TNP-LPS . The site of attachment has been suggested to be in the core polysaccharide and lipid A region of the molecule and approximately 2.4 hapten molecules are bound per monomer LPS molecule . The TNP-LPS has been demonstrated to be immunogenic in vitro at very low concentration . This antigen has further been shown to initiate a T-independent TNP-PFC response . The immunogenicity of TNP-LPS is abrogated by mild alkaline hydrolysis, suggesting a requirement for intact lipid A in the initiation of an immune respose at the very low concentrations of antigen used. J Bacteriol, 1975 Jan, 121(1), 99 - 107 Characteristics of cold-sensitive mutants of Escherichia coli K-12 defective in deoxyribonucleic acid replication; Wehr CT et al.; Four cold-sensitive mutants of Escherichia coli have been isolated which show a reduced ability to synthesize deoxyribonucleic acid at low temperature . The mutants also have a reduced ability to incorporate nucleoside triphosphates into deoxyribonucleic acid at low temperature in cell preparations made permeable with toluene . All four mutations are located at or near the dnaA locus on the E . coli genetic map . They are recessive to the wild-type allele and two of them can be integratively suppressed by F episomes. J Bacteriol, 1975 Jan, 121(1), 396 - 9 Lipid synthesis in stringent Escherichia coli: an artifact in acetate labeling of phospholipids during a shiftdown in growth rate; Nunn WD et al.; The use of (14C)acetate to label the phospholipids of stringent Escherichia coli, after a decrease in agitation, leads to artifacts resulting from a decrease in the specific activity of the acetyl coenzyme A pool. J Bacteriol, 1975 Jan, 121(1), 381 - 9 Mapping of colicin E2 and colicin E3 plasmid deoxyribonucleic acid EcoR-1-sensitive sites; Inselburg J et al.; Colicin plasmids E2 and E3 (Col E2 and Col E3) deoxyribonucleic acid (DNA) has been shown to contain, respectively, two and three EcoR1 restriction endonuclease-sensitive sites . This was determined by measuring the DNA fragments generated after EcoR1 endonuclease treatment by agarose gel electrophoresis and electron microscopy . The structure of heteroduplex Col E2-col E3 DNA molecules formed from EcoR1-generated fragments permitted a localization of the EcoR1-sensitive sites on the plasmid chromosomes. J Bacteriol, 1975 Jan, 121(1), 36 - 43 Recombination and the Escherichia coli K-12 sex factor F; Willetts NS; Recombination between two Flac tra minus elements to give Flac tra plus recombinants was measured in Rec plus and Rec minus strains of Escherichia coli K-12 . Polar tra mutations were used to increase the proportion of tra plus recombinants among the parental Flac tra minus elements transferred by complementation . The kinetics, measured in a rec plus strain, showed that recombination began about 1 h after the initiation of mating and was completed about 1 h later . Recombination was abolished in a recA minus strain, reduced by two-thirds in a recF minus strain, and unaffected in recB minus and recC minus strains . It is proposed that the part not due to the RecF pathway results from a RecBC- and RecF-independent system for formation of single-stranded joins . One such join could be followed either by transfer and a site-specific recombination event, or by a second single-stranded join and then transfer: in either case replication and inheritance of the recombinant molecule would be dependent upon the F transfer replication system . Chromosome mobilization by an F' element was normal in a recB plus recF minus strain, and was reduced only fourfold in a recB minus recF plus strain: in the latter strain, both the RecF pathway and the system for single-stranded joins may have contributed to mobilization . Measurement of post-conjugational chromosomal recombination in exponential-phase recipient cells carrying surface exclusion-deficient Flac mutants indicated that F does not itself determine a generalized recombination system able to replace the RecA plus product or the RecBC and RecF pathways. J Bacteriol, 1975 Jan, 121(1), 234 - 8 Polynucleotide sequence relationships among Ent plasmids and the relationship between Ent and other plasmids; So M et al.; Deoxyribonucleic acid-deoxyribonucleic acid hybridization studies reveal that the plasmids coding for the production of heat stable and heat labile enteroxtoxins of Escherichia coli, regardless of their origin, have a majority of their polynucleotide sequences in common, but are not related in any significant way to those plasmids coding for the synthesis of only ST toxin . The heat stable and heat labile plasmids also share a significant degree of their polynucleotide sequences with plasmids of the FI and FII incompatibility groups, but not with R factors belonging to the I, N, W, P, or X incompatibility groups. J Bacteriol, 1975 Jan, 121(1), 219 - 26 Reinitiation of deoxyribonucleic acid synthesis by deoxyribonucleic acid initiation mutants of Escherichia coli: role of ribonucleic acid synthesis, protein synthesis, and cell division; Hanna MH et al.; The dnaA and dnaC genes are thought to code for two proteins required for the initiation of chromosomal deoxyribonucleic acid replication in Escherichia coli . When a strain carrying a mutation in either of these genes is shifted from a permissive to a restrictive temperature, chromosome replication ceases after a period of residual synthesis . When the strains are reincubated at the permissive temperature, replication again resumes after a short lag . This reinitiation does not require either protein synthesis (as measured by resistance to chloramphenicol) or ribonucleic acid synthesis (as measured by resistance to rifampin) . Thus, if there is a requirement for the synthesis of a specific ribonucleic acid to initiate deoxyribonucleic acid replication, this ribonucleic acid can be synthesized prior to the time of initiation and is relatively stable . Furthermore, the synthesis of this hypothetical ribonucleic acid does not require either the dnaA of dnaC gene products . The buildup at the restrictive temperature of the potential to reinitiate deoxyribonucleic acid synthesis at the permissive temperature shows rather complex kinetics the buildup roughly parallels the rate of mass increase of the culture for at least the first mass doubling at the restrictive temperature . At later times there appears to be a gradual loss of initiation potential despite a continued increase in mass . Under optimal conditions the increase in initiation potential can equal, but not exceed, the increase in cell division at the restrictive temperature . These results are most easily interpreted according to models that postulate a relationship between the initiation of deoxyribonucleic acid synthesis and the processes leading to cell division. J Bacteriol, 1975 Jan, 121(1), 165 - 72 Detection of nonintegrated plasmid deoxyribonucleic acid in the folded chromosome of Escherichia coli: physiochemical approach to studying the unit of segregation; Kline BC et al.; Physiocochemical evidence presented indicates plasmid deoxyribonucleic acid (DNA) can associate with host chromosome without linear insertion of the former into the latter . This conclusion is based on the observation that covalently closed circular (CCC) plasmid DNA can cosediment with undegraded host chromosome in a neutral sucrose gradient . When F plus bacteria are lysed under conditions that preserve chromosome, approximately 90% of CCC F sex factor plasmid (about 1% of the total DNA) is found in folded chromosomes sedimenting at rates between 1,500 and 4,000s . The remaining 10% of the CCC F DNA sediments at the rate (80S) indicative of the free CCC plasmid form . Reconstruction experiments in which 80S, CCC F DNA is added to F plus or F minus bacteria before cell lysis show that exogenous F DNA does not associate with folded chromosomes . In F plus bacteria, F plasmid is harbored at a level of one or two copies per chromosomal equivalent . In bacteria producing colicin E1, the genetic determinant of this colicin, the Col E1 plasmid, is harbored at levels of 10 to 13 copies per chromosomal equivalent; yet, greater than 90% of these plasmids do not cosediment with the 1,800S species of folded chromosome . However, preliminary evidence suggests one or two Col E1 plasmids may associate with the 1,800S folded chromosome . Based on evidence presented in this and other papers, we postulate F plasmid can link to folded chromosome because the physicochemical structure of the plasmid resembles a supercoiled region of the chromosome and, therefore, is able to interact with the ribonucleic acid that stabilizes the folded chromosome structure . Implications of this model for F plasmid replication and segregation are discussed. Immunology, 1975 Jan, 28(1), 59 - 70 The effect of various immunosuppressive agents on mouse peritoneal macrophages and on the in vitro phagocytosis of Escherichia coli O4:K3:H5 and degradation of 125I-labelled HSA-antibody complexes by these cells; Gadeberg OV et al.; Large doses of hydrocortisone, cyclophosphamide, and methotrexate injected subcutaneously, and whole-body irradiation (500 rads) caused a reduction in the number of peritoneal cells (PE cells) obtained after intraperitoneal injection of the treated mice with proteose-peptone . The same dose of cyclophosphamide and irradiation induced morphological changes in PE macrophages . There were more giant cells in the peritoneal exudates from treated mice as compared to control mice . 'Pharmacological' and larger doses of hydrocortisone, methotrexate and azathioprine or anti-lymphocyte globulin had no effect on the in vitro phagocytic capacity of proteose-peptone-stimulated mouse PE macrophages . This also applied to doses of up to 50 mg/kg of cyclophosphamide . In contrast, whole-body irradiation (500 rad) and 100 mg/kg of cyclophosphamide decreased the phagocytic capacity of mouse macrophages in vitro and reduced the ability of PE cells to degrade 125I-labelled HSA-antibody complexes in vitro . The greatest effect was noted 4-5 days after whole-body irradiation or four to five subcutaneous injections of cyclophosphamide. Folia Microbiol (Praha), 1975, 20(1), 8 - 16 DNA synthesis - dependent cell division of Escherichia coli 15 TAU after arginine and uracil starvation; Lhotska M et al.; Extensive cell division after synchronization of Escherichia coli 15 TAU by arginine and uracil starvation occurs only when DNA synthesis is permitted to proceed by at least a short pulse of thymine applied between 30 and 60 min after transfer of synchronized culture to thymine-free medium with arginine and uracil . The time schedule of synchronized cell division in dependence on the schedule of intervals of DNA synthesis and inhibition of DNA synthesis was determined . The termination of replication cycles which were not completed to the very end during arginine and uracil starvation seems to be the decisive event for subsequent cell division after synchronization. Folia Microbiol (Praha), 1975, 20(1), 17 - 23 A study on the effect of certain compound during elimination of plasmids in Escherichia coli; Rytir V et al.; Of several chemicals tested on the elimination of plasmids from Escherichia coli K-12, the compound designated ICR-170 was most effective, applied at 100 mu g/ml, the effect being comparable to that of acriflavin . It had no effect on the elimination of the R1 plasmid from Escherichia coli JC 5455. Farmaco {Sci}, 1975 Jan, 30(1), 20 - 34 {Pyrazolic sulfanilamides . XIV . Hydroxyderivatives of 1-phenyl-5-sulfanilamidopyrazole and of 1-phenyl-3-methyl-5-sulfanilamidopyrazole}; Alberti C et al.; A report is given of the variations in bacteriostatic activity on introduction of a hydrophilic group, the hydroxyl group (-OH), at positions 2',3' and 4' of the phenyl group linked to the heterocyclic nitrogen os 1-phenyl-5-sulfanilamidopyrazole (I: R = -H) and of 1-phenyl-3-methyl-5-sulfanilamidopyrazole (II: R = -H) . The substances prepared for this purpose: 1-(hydroxyphenyl)-5-sulfanilamidopyrazoles (Ia)(Ib))(Ic)(-OH at 2', 3',4') and 1-(hydroxyphenyl)-3-methyl-5-sulfanilamidopyrazoles (IIa)(IIb)(IIc)(-OH at 2',3'4') in vitro tests of bacteriostatic activity against strains of S . aureus and E . coli gave the following results: See journal for results. Chem Biol Interact, 1975 Jan, 10(1), 41 - 55 Intermolecular linking and fragmentation of DNA by beta-propiolactone, a monoalkylating carcinogen; Kubinski H et al.; Brief exposure to beta-propiolactone (BPL) increases the sedimentation rate of purified Escherichia coli DNA in neutral and alkaline sucrose gradients . However, when electrophoresed in polyacrylamide-agarose gels, this BPL-treated DNA moves ahead of the control . Longer incubation with BPL gives rise to two new fractions, the first one sedimenting as a heterogeneous material of 6-8S, and the second one of very high sedimentation velocity . In acrylamide-agarose gels, the first fraction is again recovered in the 6-8S area, while the second fraction does not enter the gel at all . The DNA at this stage is hyperchromic in ultraviolet light suggesting that as much as 20% may be denaturated . Coliphage lambda DNA treated briefly with BPL and spread in a protein monolayer appears under the electron microscope as a rigid, extended molecule, up to 15% longer than the control DNA, and usually in compact, folded configurations suggesting intramolecular linking . After longer exposure, localized denaturation associated with single-strand breaks is observed . The single-stranded "whiskers" then interact with other DNA molecules, creating highly complex branched networks of single- and multi-stranded DNA . The possible relevance of these observations to the mechanisms involved in carcinogenesis and mutagenesis is considered. Can J Microbiol, 1975 Jan, 21(1), 27 - 33 Inhibition and amplification of the radiation-induced degradation of DNA in Escherichia coli; Myers DK; The degradation of DNA in a repair-proficient strain (B/r) and in two repair-defective strains (Bs-1 and pol A) of Escherichia coli was studied in the presence and absence of three metabolic inhibitors after exposure of the cells to X-radiation . The radiation-induced degradation of DNA was dependent on energy production in freshly harvested log-phase cells and was closely related to the repair capacity of the cells . A different system, probably involving nonspecific deoxyribonucleases acting at radiation-induced strand breaks, appeared to be responsible for the degradative processes in stationary-phase cells or in log-phase cells which had been aged by standing in buffered saline for 2 days before irradiation . The three inhibitors tested (caffeine, rifampin, and carbonyl cyanide m-chlorophenyl hydrazone) were all found to inhibit partially the radiation-induced degradation of DNA in E . coli cells . Under other conditions, the same three compounds amplified the degradative process . The data suggested that the amplification was due to a selective inhibition of repair processes . The degradative processes which were stimulated by X-radiation of E . coli cells show many parallels to those which are evoked by phleomycin or colicine. Acta Microbiol Pol A, 1975, 7(1), 37 - 40 Comparison of the mutagenic effects of 35S decay in Escherichia coli strains WP-2 and WP-2S; Pluciennik H et al.; Comparison was made of the lethal and mutagenic efficiency of 35S yields 35Cl transmutation of incorporated 35S in cells of Escherichia coli strain WP-2 and WP-2S (UV-sensitive) . Bacteria were stored at minus 196 degrees . 35S yields 35Cl transmutation induced a higher lethal effect in strain WP-2 than in the UV-sensitive strain WP-2S . Reversions try yields try+ were induced with an approximately similar efficiency in both strains compared. Pflugers Arch, 1975, 353(2), 151 - 7 Effect of various lysosomes and endotoxin on vascular permeability in frogs and mice; Csako G et al.; Blood-lymph permeability increasing effects of frog liver lysosomes, Escherichia coli 0111 endotoxin, bradykinin and serotonin were demonstrated in frogs with a method developed by the authors . These actions were expressed in a faster dye saturation in the lymph as compared to that of the controls . 2 . The method is based on the determinations of concentration of Evans blue transported as protein-bound dye into the lymph . 3 . Frog liver and polymorphonuclear leukocyte lysosomes had a capillary permeability increasing action tested by local skin response when injecting Evans blue intravenously in mice . 4 . All these phenomena are similar to events described earlier in mammalian systems. J Gen Microbiol, 1975 Jan, 86(1), 111 - 4 Thermosensitive production of their transfer systems by group S plasmids; Rodriguez-Lemoine V et al.; Transfer of plasmids of group S is much more efficient at low temperatures (e.g . 22 degrees C) than at 37 degrees C . This is due to failure of the donor strain to produce the transfer system during growth at the higher temperature. Can J Comp Med, 1975 Jan, 39(1), 46 - 53 The effect of antisera on porcine enteropathogenic Escherichia coli in ligated segments of pig intestine; Enweani CC et al.; Nineteen antisera produced in pigs against 14 enteropathogenic and five nonenterotoxigenic porcine strains of Escherichia coli were tested for their ability to inhibit gut loop fluid accumulation induced by homologous and heterologous organisms . In addition, four antisera produced in pigs by an intensive series of intravenous inoculations and three by a less intensive series of intramuscular injections of a polyvalent E . coli vaccine were evaluated . Antisera were also produced in rabbits against eight strains of porcine enteropathogens and tested in pig gut loops . Fluid inhibiting activity was detected in prevaccinal sera of pigs but not of rabbits . This activity was significantly increased following immunization . When single strains of E . coli were used for immunization the activity of the antisera against heterologous organisms varied considerably from one test strain to another and was usually much less than that against the homologous organism . The activity against heterologous organisms could not be associated with relatedness of the O, K and H antigens of the vaccine and the test strains . Antisera produced against a vaccine made by combining three strains were shown to exert inhibitory effects on heterologous organisms similar to those against homologous organisms . Considerably less activity against homologous and heterologous organisms was present in antisera produced by the series of intramuscular compared with the series of intravenous injections. Arch Ophthalmol, 1975 Jan, 93(1), 56 - 61 Intravitreal injection of cephaloridine in the treatment of endophthalmitis; Graham RO et al.; Ocular toxic effects of intravitreal injection of cephaloridine in rabbits was evaluated, and none were produced in doses of 0.25 mg or less . Clinically, intravitreal injection of cephaloridine in doses of 5 mg or more produced small punctate hemorrhages in the vascularized portions of the rabbit retina within two days . With doses of 2.5 mg or less, no clinical changes were seen during the two weeks of observation . Histologically, one day following intravitreal injection of 0.5 to 10 mg of cephaloridine there was clumping of the outer segments of the photoreceptors and destruction of the retinal pigment epithelium . Ten milligrams of cephaloridine intravitreally injected caused definite electroretinogram (ERG) changes ten minutes after injection . After 24 hours, the ERG was extinguished . An experimentally induced Escherichia coli endophthalmitis was successfully treated after six hours by intravitreal injection of cephaloridine. Acta Biol Med Ger, 1975, 34(11-12), 1767 - 75 {Action of the systemic fungicide dexon on several NADH dehydrogenases}; Schewe T et al.; The fungicide dexon (p-dimethylaminobenzenediazosulfonate, Na-salt) inhibits the NADH oxidase activity of submitochondrial particles (ETP) from beef heart (semi-inhibition concentration 1.4 muM), while the succinate oxidase activity is unaffected . Measurements of the activity of several enzymatic partial reactions of the respiratory chain of ETP suggest that dexon acts directly on the flavine of NADH dehydrogenase . Soluble NADH-cytochrome c-oxidoreductase (MAHLER) and rotenone-insensitive NADH ubiquinone reductase are also inhibited by dexon . At low concentrations of dexon, inhibition of ETP starts slowly only after addition of NADH . Preincubation without NADH increases the amount of inhibition, but does not prevent the time delay . It is assumed that an electron flux through the respiratory chain, or reduction of flavine is prerequisite for the reaction of dexon with the action site . Furthermore, dexon inhibits the NADH dehydrogenase located at the outer surface of the inner membrane of plant mitochondria, accessible to extramitochondrial NADH and insensitive to rotenone, as has been shown on isolated mitochondria from cauliflower (Brassica oleracea L) . In addition, dexon inhibits selectively the NADH dehydrogenase of the DT diaphorase (ERNSTER) from rat liver cytosol . In contrast, the dicoumarol-insensitive NADH dehydrogenase (ZINSMEYER et al.) from rat liver cytosol, the NADH-cytochrome b5-reductase (STRITTMATTER) from rat liver microsomes, the rotenone-insensitive NADH-cytochrome c-oxidoreductase of the outer membrane of rat liver mitochondria, soluble NADH-oxidase from Escherichia coli, and NADH-dehydrogenase from human erythrocytes are not inhibited . The results suggest that dexon is a group reagent to certain pyridine nucleotide-dependent flavine enzymes. Genetika, 1975, 11(8), 154 - 70 {Current problems of molecular genetics}; Khesin RB; Some problems of molecular genetics are considered . A special attention is paied to enzymology of genetic processes, in particular, to the mechanism of DNA replication, gene ingeneering and the structure and activity regulation mechanisms of genetic loci in higher organisms. Basic Life Sci, 1975, 5B, 763 - 71 Excision-repair of 4-nitroquinolin-1-oxide damage responsible for killing, mutation, and cancer; Ikenaga M et al.; Excision-repair of DNA base damage produced by 4-nitroquinoline-1-oxide (4NQO) was compared in Escherichia coli, human cells, and mouse cells . Paper chromotography of acid hydrolysates of DNA extracted from cells treated with 3H-labeled 4NQO revealed four peaks; two kinds of 4NQO-guanine adduct, one kind of 4NQO-adenine adduct, and free 4-aminoquinoline-1-oxide (4AQO) . About 80% of the initially formed 4NQO-purine adducts were excised from DNA in E . coli uvrA+ cells during 60 min postincubation, but not at all in uvrA- (excisionless for uv damage) cells . Normal human cells excised about 60% of 4NQO-purine adducts during 24 hr postincubation, but xeroderma pigmentosum (excisionless) cells did not . A mouse cell line susceptible to repair of 4NQO-induced pretransformational damage also showed excision-repair ability for the 4NQO adducts . From these and other results, we conclude that the 4NQO-purine adducts and unstable 4NQO-guanine products (which release 4AQO) are, like pyrimidine dimers, repairable by excision-repair universal among E . coli, mouse, and human being, and that unexcised ones are probably the major cause of killing, mutation, and cancer. Mol Gen Genet, 1975, 137(4), 289 - 304 Regulated in vitro synthesis of the enzymes of the deo operon of Escerichia coli . properties of the DNA directed system; Svenningsen BA; The four enzymes deoxyriboaldolase, thymidine phosporylase, deoxyribomutase, and purine nucleoside phosphorylase have been synthesized in substantial amounts in a DNA-dependent in vitro system programmed with DNA containing the deo operon . The synthesis is greatly stimulated by deoxyribose-5-phosphate and cyclic AMP indicating that the deoR repressor and the catabolite activating protein (CAP) are highly active under our cell-free conditions . In contrast it has not yet been possible to observe a reproducible effect of the cytR repressor in vitro . The sequential appearance of active enzymes has confirmed the direction of transcription as being dra-tpp-drm-pup and has indicated that the four genes are transcribed into a single tetracistronic message. Trans Am Soc Artif Intern Organs, 1975, 21, 156 - 64 Reduction of canine serum asparagine levels by L -asparaginase immobilized on collagen: a potential form of cancer chemotherapy; Olanoff LS et al.; These results suggest that asparaginase-collagen preparations, with activity and stability values surpassing those reported for other immobilization procedures, can be potentially utilized as an efficient extracorporeal chemptherapeutic device for the treatment of tumors, producing less side effects than the soluble enzyme therapy, for a given level of asparagine clearance. Environ Physiol Biochem, 1975, 5(1), 37 - 48 Vitamin B12 absorption in x-irradiated rats; D'Souza DW et al.; The effect of whole-body exposure of rats to a sub-lethal dose (400 rad) of x-rays on the absorptive capacity of intestinal mucosal cells for vitamin B12 has been studied . The rate of absorption of vitamin B12 from the intestinal loops is decreased in x-irradiated rat . Inclusion of gastric juice from normal rat does not improve the rate . A severe interference in the absorption and retention of orally fed (57-Co)-B12, as evidenced by low serum levels, decreased organ uptake and increased excretion, is observed . However, when the vitamin is administered intraperitoneally, its uptake by organs is not affected in the irradiated animal . This suggests that the observed morphological degeneration of mucosal cells in x-irradiated rats is the main reason for the malabsorption of vitamin B12 . Atrophy of intestinal cells in the protein-fasted rat accentuates the adverse effects of radiation . A sharp drop in viable intestinal flora is observed within 24 h post-irradiation, but there is an increase after 3 days. Biochimie, 1975, 57(2), 175 - 225 Nucleotide sequences of the T1 and pancreatic ribonuclease digestion products from some large fragments of the 23S RNA of Escherichia coli; Branlant C et al.; When the 23S RNA from E . Coli was pretreated for 1 h at 60 degrees in the presence of Mg++ and K+ and then subjected to T1 ribonuclease attack, resistant fragments were recovered from 3 regions of the molecule: region A (containing 470-500 nucleotides) located at the 5' end of 23S RNA, region B (containing 520-550 nucleotides) located at the 3' end and region C (containing 110-120 nucleotides) lying between region A and region B . The nucleotide sequences of the T1 and pancreatic ribonuclease digestion products from these 3 regions have been studied and in most cases determined . In the course of these studies, a certain number of abnormal nucleotides, which are not methylated, have been encountered . A low level of sequence heterogeneity was detected. Bull Exp Biol Med, 1975 Jan, 77(7), 795 - 7 Interaction between Bdellovibrio bacteriovorus and the cytoplasmic membrane of Escherichia coli B; Komissarova LV et al.; Adsorption of Bdellovibrio bacteriovours (Bdv) on the surface of Escherichia coli is accompanied by a sharp decrease in the initial rate of entry of alpha-methylglucoside-C-14 and thiomethlgalactopyranoside-C-14 into the host cell . Interaction between the parasite and E . coli leads to the rapid departure of previously accumulated labeled glucosides and beta-galactosides from the bacteria . Meanwhile the ATPcontent in E . coli falls sharply . Adsorption Bdv E.coli spheroplasts was established as a fact . The possible mechanisms of interaction between Bvd and the host cell at the cytoplasmic membrane level are discussed. Acta Biol, 1975, 26(3-4), 217 - 23 On the metabolic radioprotection; Hernadi F et al.; The effect of different factors (0.025 mol/l of cysteine, 0.0003 mol/l of iodoacetamide, 0.328 mol/l of hydroxyurea, deprivation of glucose or essential amino acid and uracil from the medium) on the resistance to gamma rays was studied in the cells of E . coli TAU- during the logarithmic phase . The resistance to gamma rays was also investigated during the stationary phase . It was established that treatments, including reversible inhibition of cell division and unbalance of macromolecular synthesis of a type in which the DNA synthesis was continued without a simultaneous RNA- and protein synthesis enhanced the radioresistance . This type of asynchrony of macromolecular synthesis could increase radioresistance by promotion of repair processes of single-strand breaks in DNA after a single dose of 15 krads irradiation . For this latter studies E . coli K12 (AB 2497) strain and the technique developed by McGrath and Williams was used. Genetika, 1975, 11(3), 127 - 32 {Effect of adenine, adenosine and adenylic nucleotides on the mutagenic effect of hydroxylamine}; Vasiunina EA et al.; The effect of some adenyl precursors of DNA synthesis on the mutagenic activity of hydroxylamine (HA) is studied . It is shown that the addition of adenine to a suspension of Escherichia coli B cells increases the yield of mutants by more than two times as compared with HA alone . The effects of adenosine, AMP and dAMP are somewhat different . It is suggested that the increase of the HA mutagenic effect produced by the addition of adenine may be due to: 1) the excess of the amount of adenylic precursors of DNA synthesis over guanilic ones, which promotes the erroneous base-pairing during the replication of the HA modified template; 2) the modification of adenylic precursors by HA into N6-oxy-dATP, and their incorporation into DNA . The mutagenic effect of N6-hydroxyadenosine, the product of the adenine modification by HA, in E . coli B pur- was studied . The experiments showed that N6-hydroxyadenosine induced about 1% of mutations, a relatively low lethal effect (the cell survival was 80%), and provided a high mutagenic action of this compound. Ann Rech Vet, 1975, 6(3), 241 - 8 {The colibacillosis of the pig (author's transl)}; Renault L; A review of recent knowledges of the specific determinants of Escherichia coli pathogenicity allows the development of new effective immunisation against the colibacillosis of the pig . Especially experimental and field trials provide promising results by oral or parenteral vaccinations, with attenuated bacteria neutralising the effect of enterotoxins or with partially purified protein surface antigen preventing bacterial attachment to the intestinal wall . However it is necessary to bear in mind the necessity of not neglecting sanitary management. Genetika, 1975, 11(3), 127 - 32 {Effect of adenine, adenosine and adenylic nucleotides on the mutagenic action of hydroxylamine}; Vasiunina EA et al.; The effect of some adenyl precursors of DNA synthesis on the mutagenic activity of hydroxylamine (HA) is studied . It is shown that the addition of adenine to a suspension of Escherichia coli B cells increases the yield of mutants by more than two times as compared with HA alone . The effects of adenosine, AMP and dAMP are somewhat different . It is suggested that the increase of the HA mutagenic effect produced by the addition of adenine may be due to: 1) the excess of the amount of adenylic precursors of DNA synthesis over guanilic ones, which promotes the erroneous base-pairing during the replication of the HA modified template; 2) the modification of adenylic precursors by HA into N6-oxy-dATP, and their incorporation into DNA . The mutagenic effect of N6-hydroxyadenosine, the product of the adenine modification by HA, in E . coli B pur- was studied . The experiments showed that N6-hyrdoxyadenosine induced about 1% of mutations, a relatively low lethal effect (the cell survival was 80%), and provided a high mutagenic action of this compound. Genetika, 1975, 11(11), 79 - 89 {Genetic study of Escherichia coli K-12 mutants resistant to 2,6-diaminopurine}; Kocharian ShM et al.; Mutants, resistant to the inhibitory effect of 2,6-diaminopurine and incapable of utilizing adenine as a purine source, are obtained from purinenucleoside phosphorylase-defective purine-dependent Escherichia coli K-12 strains . The mutations obtained (apt) disturb the uptake of adenosine and inosine only in the presence of a mutation for purinenucleoside phosphorylase (pup gene) in the genome of purine-dependent bacteria . The introduction of pup+ allele into the genome of mutants obtained (genotype purDpup apt) results in the restoration of the ability to uptake adenine and purine ribosides . Strains of purDpup+apt genotype are characterized by more short generation time under the growth in the presence of adenine as compared with purDpup apt+ strains which indicates the existance of an efficient pathway of adenine utilization in E . coli with the cooperation of purinenucleoside phosphorylase . Mutations apt have revealed a combined transfer with purE marker under the transduction frequency of approximately 5% . The gene order on E . coli K-12 chromosome is apt-p