This Week in PLoS: Dec 16, 2008

A group of researchers report in PLoS Biology that Mycobacterium tuberculosis strains that affect people are more genetically diverse than had been assumed. They studied 7 megabase pairs of DNA sequence data from 108 strains of M. tuberculosis and attribute the diversity to human demographic and migratory events. The authors also say that current human population trends, global travel, urbanization, and population growth, may be contributing to the spread of drug-resistant tuberculosis

Researchers from the Ludwig-Maximilians University mapped where the Drosophila dosage compensation complex -- which makes sure that male fruit flies have the same X-chromosome transcription levels as female flies -- is recruited. They used RNAi against DCC components, crosslinking, and ChIP-chip methods to identify high affinity sites for the DCC subunits, MSL1 and MSL2. They found high affinity sites all along the X-chromosome, mainly on noncoding parts of genes that lack histones. The rest of the DCC binding, they add, tends to occur in coding regions with methylated histones.

Japanese researchers say that interlocus gene conversion could be an important mechanism for gene duplication in Drosophila melanogaster. In their comparative genomics study, they identified 31 post-speciation duplicated genes and determined the rate of duplication to be about 1.0×10^-9 per single-copy gene per year. They also say that "gene conversion between duplicated regions is a common and genome-wide phenomenon in the Drosophila genomes, and that its role should be especially significant in the early stages of duplicated genes."

In PLoS One, Aarhus University researchers report on copy number variations found on chromosomes 4, 7, 14, and 17 of the pig genome. Using a custom tiling oligonucleotide and material from 14 boars, 700 sows and about 12,000 offspring, they identified 37 CNVRs from the four chromosomes. "As the first of its kind in pig, this study examines the extent and pattern of CNVs in the pig genome, important for future studies associating phenotype to genome architecture," the authors write.