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This Week in PLOS: Feb 25, 2013

In PLOS Biology, two University of British Columbia researchers delve into the details of evolutionary diversity, using Escherichia coli as a model system. The team prompted initially isogenic E. coli bacteria to adapt into different populations using competition experiments involving growth in distinct carbon sources over some 1,200 generations. After sequencing and assessing the genomes of bugs undergoing adaptation through three such trials, UBC's Michael Doebeli and co-author Matthew Herron, now at the University of Montana, realized that "similar but independently evolved phenotypes often shared mutations in the same gene and, in four cases, shared identical mutations at the same nucleotide position." Such parallel mutation patterns prompted the duo to propose that adaptive diversification marches along through a "predictive evolutionary process."

Researchers from France, Australia, and the US report on a random codon re-encoding strategy for designing vaccines against Chikungunya virus in PLOS Pathogens. There, the group put together six re-encoded Chikungunya genomes representing random combinations of three 1,400 base chunks of the virus's original sequence. Through genome sequencing and other analyses, the investigators tracked replicative capability and adaptive changes in randomly re-encoded genomes passaged in primate or insect cell lines over time. Because the random re-encoding method appeared capable of creating viruses with reduced replicative fitness, study authors say, the method may hold promise for producing new live-attenuated viruses that are safe and stable over time.

Low-grade gliomas tend to have distinct sets of genomic alterations compared to their high-grade counterparts, according to a PLOS One study. A Chinese research team did array-based genotyping on matched tumor-and normal samples from nine Chinese patients with low-grade glioma and nine with high-grade glioma as part of its effort to characterize chromosomal gain, loss, or copy neutral loss of heterozygosity in the central nervous system cancers. Results of the analyses indicate that "[low-grade glioma] and [high-grade glioma appear to have different molecular signatures in genomic variations," researchers say, and "provide invaluable information for the diagnosis and treatment of gliomas in patients with variable duration or diverse tumor differentiation."