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Comparative Whole-Genome Analysis of Virulent and Avirulent Strains of Porphyromonas gingivalis. Tsute Chen, 2004.We used Porphyromonas gingivalis gene microarrays to compare the total gene contents of the virulent strain W83 and the avirulent type strain, ATCC 33277 . Signal ratios and scatter plots indicated that the chromosomes were very similar, with approximately 93% of the predicted genes in common, while at least 7% of them showed very low or no signals in ATCC 33277 . Verification of the array results by PCR indicated that several of the disparate genes were either absent from or variant in ATCC 33277 . Divergent features included already reported insertion sequences and ragB, as well as additional hypothetical and functionally assigned genes . Several of the latter were organized in a putative operon in W83 and encoded enzymes involved in capsular polysaccharide synthesis . Another cluster was associated with two paralogous regions of the chromosome with a low G+C content, at 41%, compared to that of the whole genome, at 48% . These regions also contained conserved and species-specific hypothetical genes, transposons, insertion sequences, and integrases and were located adjacent to tRNA genes; thus, they had several characteristics of pathogenicity islands . While this global comparative analysis showed the close relationship between W83 and ATCC 33277, the clustering of genes that are present in W83 but divergent in or absent from ATCC 33277 is suggestive of chromosomal islands that may have been acquired by lateral gene transfer . Cloning of the Authentic Bovine Gene Encoding Pepsinogen A and Its Expression in Microbial Cells. Rosario Muñoz, 2004.Bovine pepsin is the second major proteolytic activity of rennet obtained from young calves and is the main protease when it is extracted from adult animals, and it is well recognized that the proteolytic specificity of this enzyme improves the sensory properties of cheese during maturation . Pepsin is synthesized as an inactive precursor, pepsinogen, which is autocatalytically activated at the pH of calf abomasum . A cDNA coding for bovine pepsin was assembled by fusing the cDNA fragments from two different bovine expressed sequence tag libraries to synthetic DNA sequences based on the previously described N-terminal sequence of pepsinogen . The sequence of this cDNA clearly differs from the previously described partial bovine pepsinogen sequences, which actually are rabbit pepsinogen sequences . By cloning this cDNA in different vectors we produced functional bovine pepsinogen in Escherichia coli and Saccharomyces cerevisiae . The recombinant pepsinogen is activated by low pH, and the resulting mature pepsin has milk-clotting activity . Moreover, the mature enzyme generates digestion profiles with  -, ß-, or
 -casein indistinguishable from those obtained with a natural pepsin preparation . The potential applications of this recombinant enzyme include cheese making and bioactive peptide production . One remarkable advantage of the recombinant enzyme for food applications is that there is no risk of transmission of bovine spongiform encephalopathy .
Mapping of Myxococcus xanthus Social Motility dsp Mutations to the dif Genes. Hope Lancero, 2002.Myxococcus xanthus dsp and dif mutants have similar phenotypes in that they are deficient in social motility and fruiting body development . We compared the two loci by genetic mapping, complementation with a cosmid clone, DNA sequencing, and gene disruption and found that 16 of the 18 dsp alleles map to the dif genes . Another dsp allele contains a mutation in the sglK gene . About 36.6 kb around the dsp-dif locus was sequenced and annotated, and 50% of the genes are novel .
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