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This Week in PLOS: Feb 11, 2014

A genome sequencing study in PLOS Genetics suggests the Atlantic salmon pathogen Spironucleus salmonicida may be capable of adjusting its gene expression and metabolic capabilities in response to shifting environmental conditions. Uppsala University researchers sequenced the pathogen's almost 13 million basepair genome, which contains an estimated 8,067 protein-coding genes, and went on to compare it to a related human pathogen: the diarrhea-causing Giardia intestinalis. That comparison highlighted differences in carbohydrate use and transcriptional regulation in the pathogens, for example, with S. salmonicida containing more complex metabolic capabilities and more extensive gene regulatory features.

In PLOS One, a Cornell University and US Department of Agriculture Agricultural Research Service-led team used sequencing to uncover unexpected plasticity in the genome of a Pseudomonas syringae strain that specializes in parasitizing tomato plants. By sequencing the genome of P. syringae pv. tomato DC3000, the team detected double copy number profiles for a segment spanning 165,000 bases of the pathogen's chromosome. A closer look at the region indicated that this duplication, a tandem repeat, seems to boost the bug's growth in some conditions but did not seem to alter its pathogenicity in tomato plants.

Washington University's Makedonka Mitreva and colleagues used RNA sequencing to track tissue-specific gene expression profiles in the nematode worm Ascaris suum, a parasite best known for infecting swine — work they described in PLOS Neglected Tropical Diseases. Using sequence data for samples from four reproductive tissues in the worm, along with head, pharynx, and intestinal tissue samples from both male and female worms, the team untangled gene expression and regulation networks that were distinct or shared across the 10 tissues. It also detected some of the transcription factors and transcript binding motifs at play in particular tissues in the parasitic worm.