However, it can be difficult or impossible to resolve certain issues or test particular hypotheses given the inherent limitations in such observational data. View full-textĬomparative studies of living organisms and their genomes, along with the fossil record, provide evidence for the history of life on Earth and the evolutionary processes that have shaped living systems. Our findings suggest co-evolving relationships between particular Qrr sRNAs and particular mRNA targets. Sequence comparisons reveal that Vibrionaceae species possessing only qrr1 do not have the aphA gene under Qrr sRNA control. However, Qrr1 is equally effective as the other Qrr sRNAs at controlling targets like luxR and luxO because it harbours all of the required pairing regions for these targets. Qrr1 is not as effective as Qrr2-5 in activating aphA because Qrr1 lacks one of two required pairing regions. We find that the Qrr sRNAs use unique pairing regions to discriminate between their different targets. Here we show that the Qrr sRNAs post-transcriptionally activate production of the low cell density master regulator AphA through base pairing to aphA mRNA, and this is crucial for the accumulation of appropriate levels of AphA protein at low cell density. expression pattern by modulating translation of multiple mRNAs encoding quorum-sensing regulatory factors. In the Vibrio harveyi and Vibrio cholerae quorum-sensing circuits, multiple non-coding small regulatory RNAs called the quorum-regulated small RNAs (Qrr sRNAs) function to establish the global quorum-sensing gene. Quorum sensing is a mechanism of cell-cell communication that bacteria use to control collective behaviours including bioluminescence, biofilm formation and virulence factor production.
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