In an advance, online publication of PNAS this week, researchers at the J. Craig Venter Institute and their colleagues report their inference of the history of biological metal utilization via comparative phylogenomic analysis of protein structures. Because "all of life exhibits the same proteome size-dependent scaling for the number of metal-binding proteins within a proteome," the team writes, the "fundamental evolutionary constant shows that the selection of one element occurs at the exclusion of another, with the eschewal of Fe for Zn and Ca being a defining feature of eukaryotic proteomes." The authors suggest that Zn bioavailability could have been a limiting factor in eukaryotic evolution.
Researchers in The Netherlands present evidence that "acute stress modulates genotype effects on amygdala processing in humans" in PNAS this week. In examining gene-environment interactions that affect neural processing, and by inducing acute psychological stress, the team probed amygdala responses. They show that "only carriers of a common functional deletion in ADRA2B, the gene coding for the α2b-adrenoreceptor, displayed increased phasic amygdala responses under stress."
In the PNAS Early Edition, investigators at the University of Minnesota and their colleagues report their method for targeted mutagenesis of Arabidopsis genes using the regulated expression of zinc finger nucleases. "The high frequency of observed ZFN-induced mutagenesis suggests that targeted mutations can readily be recovered by simply screening progeny of primary transgenic plants by PCR and DNA sequencing," the authors write, adding that their results suggest it is "possible to obtain mutations in any Arabidopsis target gene regardless of its mutant phenotype."
In a related Early Edition paper, a trio of researchers in Japan demonstrates their targeted-gene inactivation using zinc finger nucleases in Arabidopsis. "These data demonstrate that an approach using ZFNs can be used for the efficient production of mutant plants for precision reverse genetics," the authors suggest.