In this week's PNAS Early Edition, an international team led by investigators at Yunnan University in China shows that because of "highly variable recessive lethal or nearly lethal mutation rates during germline development of male Drosophila melanogaster," researchers' "conclusions or analyses ... based on equal mutation rates during development should be taken with caution." The team also reports a statistical approach to combat the variability issue it observed, which "can be adopted for studying other organisms, including the human germline or somatic mutational patterns."
Also in the Early Edition, researchers at the University of Exeter and elsewhere in the UK present evidence to suggest that "horizontal gene transfer facilitated the evolution of plant parasitic mechanisms in the oomycetes." In particular, using comparative genomics the Exeter-led team reports transfers involving "gene products with the capacity to break down plant cell walls and acquire sugars, nucleic acids, nitrogen, and phosphate sources from the environment." The team adds that its results "are consistent with the hypothesis that some oomycetes became successful plant parasites by multiple acquisitions of genes from fungi."
In another PNAS paper published online in advance, researchers at the Stanford University School of Medicine and the University of Buffalo in New York report their generation of a Timothy syndrome 2-like mouse, which, when kept in an inverted neomycin cassette, survived through adulthood and recapitulated several behavioral phenotypes associated with the autism spectrum disorder of known monogenic cause. "Capitalizing on this unique opportunity to use the TS [Timothy syndrome] mutation to model ASD [autism spectrum disorders] in mice," the researchers found "TS2-neo mice showed markedly restricted, repetitive, and perseverative [sic] behavior, altered social behavior, altered ultrasonic vocalization, and enhanced tone-cued and contextual memory following fear conditioning."