In PLOS Genetics, the University of California, Santa Cruz's Beth Shapiro and colleagues from the US, Russia, and Canada present evidence for a relatively straightforward model for polar bear evolution. Using genomic sequence data on seven polar bears, one black bear, one mainland brown bear, and one brown bear from Alaska's Admiralty, Baranof, and Chichagof, or ABC, islands, the team uncovered an over-representation of polar bear sequences on the ABC brown bear X chromosome. Together with existing genetic data, the findings seem to support the notion that female polar bears mixed with male brown bears on the Alaskan islands long ago, eventually reverting to a brown bear-like population. If so, researchers say, it puts the polar bear-brown bear divergence time prior to this mixing event, with present-day polar bears likely carrying relatively little in the way of recent brown bear ancestry.
Our sister publication GenomeWeb Daily News has more on the study.
A University of Waterloo team has sequenced the genome of a Pseudomonas bacterial strain that lives in the region around reed plant roots and is known for boosting the plant's growth. As the researchers write in PLOS Pathogens, they identified an estimated 5,423 protein-coding genes in the nearly 6.2 million-base-pair genome of the strain, known as Pseudomonas sp. UW4. The sequence has already helped the group see some genes predicted to bolster growth of nearby plants and the fitness of the bacterial strain itself, study authors note, adding that "the availability of the whole genetic contents of this organism will surely help to provide more insight in unraveling the complex biological mechanisms that UW4 and other similar organisms use to promote plant growth."
A team from the US and Singapore takes a look at the spread of yellow fever virus across Africa using a phylogeny-focused approach in PLOS Neglected Tropical Diseases. The researchers brought together sequence data for 26 yellow fever virus isolates from Africa, including seven East and Central African isolates not published in the past. From a phylogenetic analysis based on 49 partial yellow fever virus coding sequences, they determined relationships and divergence times for African lineages of the mosquito-spread scourge — patterns that are useful for retracing its transmission on the continent and perhaps for coming up with surveillance and vaccination schemes.