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PNAS Papers on South American Population History, Venom Network, More

Editor's Note: Some of the articles described below are not yet available at the PNAS site, but they are scheduled to be posted this week.

Investigators in Brazil and Spain describe an Australasian-related ancestry signal that they saw in South American individuals from Amazonian and coastal Pacific populations. Using genotyping profiles for 383 individuals from South America, the team detected Australian-, Melanesian-, Onge-, and Papuan-related ancestry in Karitiana and Surui populations in Brazil's Amazon and in populations from central, central west, and the Pacific coast regions, though the specific sequences varied within and between populations. "Our results showed that the Australasian genetic signal, previously described as exclusive to Amazonian groups, was also identified in the Pacific coastal population," the authors report, "pointing to a more widespread signal distribution within South America, and possibly implicating an ancient contact between Pacific and Amazonian dwellers."

A team from Japan and Australia takes a look at the co-expressed genes and regulatory features involved in venom production in the Taiwan habu (Protobothrops mucrosquamatus). Starting with available Taiwan habu transcriptome libraries, the researchers used weighted gene co-expression network analyses on the venom gland and other tissues to identify thousands of genes in a meta-venom network that appeared to be conserved in the mammalian salivary gland and in other amniotic animals. "We traced the origin of this network to the common ancestor of amniotes, which suggests that the venom system originated from a conserved gene regulatory network," they write. "The conserved nature of the meta-venom network across amniotes suggests that oral venom systems started with a common gene regulatory foundation, and underwent lineage-specific changes to give rise to diverse venom systems in snakes, lizards, and even mammals."

German researchers report on findings from a reverse genetic analysis of the respiratory syncytial virus (RSV), a common contributor to respiratory infections in young children. After plopping full-length complementary DNA versions of clinically relevant RSV isolate antigenomes into a bacterial artificial chromosome system, the investigators searched for recombinant reporter rescue strains, narrowing in on mutations that appear to bolster RSV escape from a humanized monoclonal antibody treatment called palivizumab. Based on their initial findings, the authors suggest that similar reverse genetic systems "will facilitate future cross-validation efficacy studies of novel RSV therapeutic intervention strategies and investigations into viral and host factors necessary for virus entry and cell-to-cell spread."