Expression profiling reveals Spot 42 small RNA as a key regulator in the central metabolism of Aliivibrio salmonicida.

BACKGROUND: Spot 42 was discovered in Escherichia coli nearly 40 years ago as an abundant, small and unstable RNA. Its biological role has remained obscure until recently, and is today implicated in having broader roles in the central and secondary metabolism. Spot 42 is encoded by the spf gene. The gene is ubiquitous in the Vibrionaceae family of gamma-proteobacteria. One member of this family, Aliivibrio salmonicida, causes cold-water vibriosis in farmed Atlantic salmon. Its genome encodes Spot 42 with 84% identity to E. coli Spot 42. RESULTS: We generated a A. salmonicida spf deletion mutant. We then used microarray and Northern blot analyses to monitor global effects on the transcriptome in order to provide insights into the biological roles of Spot 42 in this bacterium. In the presence of glucose, we found a surprisingly large number of ≥ 2X differentially expressed genes, and several major cellular processes were affected. A gene encoding a pirin-like protein showed an on/off expression pattern in the presence/absence of Spot 42, which suggests that Spot 42 plays a key regulatory role in the central metabolism by regulating the switch between fermentation and respiration. Interestingly, we discovered an sRNA named VSsrna24, which is encoded immediately downstream of spf. This new sRNA has an expression pattern opposite to that of Spot 42, and its expression is repressed by glucose. CONCLUSIONS: We hypothesize that Spot 42 plays a key role in the central metabolism, in part by regulating the pyruvat dehydrogenase enzyme complex via pirin.

Hydrocarbon products and their derivatives in fish of the Pechora River, North-Eastern European Russia.

Analysis of one of the major surface oil spill consequences, which took place in 1994 on the territory of the Pechora River (Russia) catchment area, was carried out. Data on hydrocarbon products and their derivatives concentrations in muscle and liver tissues of several fish species living in the Pechora's Delta and the river tributaries were obtained. Comparative analysis of OCCs, PCBs and PAHs concentrations in 1997 and 2008 showed that levels of all examined pollutants in fish tissues are very low. At the same time, in 2008 OCCs and PCBs concentrations in fish were lower compared to 1997, except for PAHs concentrations in Pechora Delta whitefish, which demonstrate the opposite tendency in relation to two compounds for the last 11 years.