|
|
|
|
|
|
Genetic Characterization and Transmission Cycles of Cryptosporidium Species Isolated from Humans in New Zealand. James J. Learmonth, 2004.Little is known about the genetic characteristics, distribution, and transmission cycles of Cryptosporidium species that cause human disease in New Zealand . To address these questions, 423 fecal specimens containing Cryptosporidium oocysts and obtained from different regions were examined by the PCR-restriction fragment length polymorphism technique . Indeterminant results were resolved by DNA sequence analysis . Two regions supplied the majority of isolates: one rural and one urban . Overall, Cryptosporidium hominis accounted for 47% of the isolates, with the remaining 53% being the C . parvum bovine genotype . A difference, however, was observed between the Cryptosporidium species from rural and urban isolates, with C . hominis dominant in the urban region, whereas the C . parvum bovine genotype was prevalent in rural New Zealand . A shift in transmission cycles was detected between seasons, with an anthroponotic cycle in autumn and a zoonotic cycle in spring . A novel Cryptosporidium sp., which on DNA sequence analysis showed a close relationship with C . canis, was detected in two unrelated children from different regions, illustrating the genetic diversity within this genus . In Vivo Effect of Mutations at the PRPP Binding Site of the Bacillus subtilis Purine Repressor. Pekka Rappu, 2003.The Bacillus subtilis PurR mediates adenine repression and guanosine induction of purA . PRPP inhibits binding of PurR to DNA in vitro . Mutations in the PRPP binding motif of PurR caused strong repression regardless of purine exclusions or additions, establishing the role of PRPP as regulator of PurR . Homologous npdGI Genes in 2,4-Dinitrophenol- and 4-Nitrophenol-Degrading Rhodococcus spp.. Gesche Heiss, 2003.Rhodococcus (opacus) erythropolis HL PM-1 grows on 2,4,6-trinitrophenol or 2,4-dinitrophenol (2,4-DNP) as a sole nitrogen source . The NADPH-dependent F420 reductase (NDFR; encoded by npdG) and the hydride transferase II (HTII; encoded by npdI) of the strain were previously shown to convert both nitrophenols to their respective hydride Meisenheimer complexes . In the present study, npdG and npdI were amplified from six 2,4-DNP degrading Rhodococcus spp . The genes showed sequence similarities of 86 to 99% to the respective npd genes of strain HL PM-1 . Heterologous expression of the npdG and npdI genes showed that they were involved in 2,4-DNP degradation . Sequence analyses of both the NDFRs and the HTIIs revealed conserved domains which may be involved in binding of NADPH or F420 . Phylogenetic analyses of the NDFRs showed that they represent a new group in the family of F420-dependent NADPH reductases . Phylogenetic analyses of the HTIIs revealed that they form an additional group in the family of F420-dependent glucose-6-phosphate dehydrogenases and F420-dependent N5,N10-methylenetetrahydromethanopterin reductases . Thus, the NDFRs and the HTIIs may each represent a novel group of F420-dependent enzymes involved in catabolism . Isolation and Identification of Actinobacteria from Surface-Sterilized Wheat Roots. Justin T. Coombs, 2003.This is the first report of filamentous actinobacteria isolated from surface-sterilized root tissues of healthy wheat plants (Triticum aestivum L.) . Wheat roots from a range of sites across South Australia were used as the source material for the isolation of the endophytic actinobacteria . Roots were surface-sterilized by using ethanol and sodium hypochlorite prior to the isolation of the actinobacteria . Forty-nine of these isolates were identified by using 16S ribosomal DNA (rDNA) sequencing and found to belong to a small group of actinobacterial genera including Streptomyces, Microbispora, Micromonospora, and Nocardiodes spp . Many of the Streptomyces spp . were found to be similar, on the basis of their 16S rDNA gene sequence, to Streptomyces spp . that had been isolated from potato scabs . In particular, several isolates exhibited high 16S rDNA gene sequence homology to Streptomyces caviscabies and S . setonii . None of these isolates, nor the S . caviscabies and S . setonii type strains, were found to carry the nec1 pathogenicity-associated gene or to produce the toxin thaxtomin, indicating that they were nonpathogenic . These isolates were recovered from healthy plants over a range of geographically and temporally isolated sampling events and constitute an important plant-microbe interaction .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
