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.
An international team of researchers combined species distribution models and population genomics to explore how Pyura praeputialis spread from Australia to Chile. As they report in the Proceedings of the National Academy of Sciences this week, researchers led by the University of Southampton's Marc Rius collected P. praeputialis samples from Chile and Australia for genetic analysis. They found high genetic diversity among both the Chilean and Australian samples, though traced the invasive samples' origins to just one region of Australia. They further suggest that P. praeputialis could spread further in Chile, as they uncovered more than 3,500 kilometers of suitable habitat for it, which could threaten biodiversity there.
Researchers led by Clemson University's Trudy Mackay uncovered a number of genetic variants associated with cocaine or methamphetamine consumption among the fruit fly Drosophila melanogaster. They examined voluntary consumption of the drugs among flies and sequenced the high-consuming flies and a similar number of randomly chosen flies. Overall, the researchers tied more than 3,000 gene variants to increased cocaine or methamphetamine consumption. They further analyzed 22 candidate genes using RNAi and other analyses, and found nine SNPs with significant effects on drug consumption in at least one sex.
Lastly, researchers from the US, China, and Czech Republic sequenced and analyzed the maize B chromosome, a representative of the nonvital chromosome is found throughout plant and animal genomes. Within the 125.9-Mb B chromosome, they uncovered 758 protein-coding genes and noted transposable elements shared between the B chromosome and the standard A chromosomes. The new assembly further provides insight into how the B chromosome is formed, suggesting that the B chromosome-specific ZmB repeats located near the centromere serve as the cis factor mediating non-disjunction.