In this week's Science, an international team of researchers analyzed the genome sequences of 16 species of anopheline mosquitoes for insights into the spread of malaria. They sequenced and assembled the genomes and transcriptomes of 16 anophelines, spanning about 100 million years of evolution. Between roughly 11,000 and 16,000 protein-coding genes for each species were generated by genome annotation, supported with RNA sequencing transcriptomes. The researchers reported that relative to Drosophila, Anopheles "exhibits a dynamic genomic evolutionary profile," and comparative analyses demonstrated a five-fold faster rate of gene gain and loss, "elevated gene shuffling on the X chromosome," and more intron losses in Anopheles. Further, they saw evidence of variation in important reproductive phenotypes, genes controlling immunity to Plasmodium malaria phenotypes and other microbes, genes encoding cuticular and salivary proteins, and genes conferring metabolic insecticide resistance. They concluded that Anopheles has a molecular evolutionary profile "very distinct" from Drosophila, and the Anopheles genomes harbor evidence of "functional variation in traits that determine vectorial capacity." The new reference genomes, they said, could serve as a foundation for hypothesis generation "and testing to further our understanding of the diverse biological traits that determine vectorial capacity."
Also in Science, a Swiss team of scientists reported a study demonstrating how the cholera pathogen uses a toxin to kill neighboring cells so that it can ingest and integrate their DNA for its own purposes. Bacteria often integrate the DNA of other cells to aid in their own evolution through a process called horizontal gene transfer, which has been associated with antibiotic resistance and virulence. According to the new data, cholera takes a predatory approach to horizontal gene transfer, using genes involved in DNA uptake to assemble a long tube that pierces nearby cells and delivers toxin. The dead cells then release their DNA, which is collected by the cholera bacterium.