Genome-wide analysis of myxobacterial two-component systems: genome relatedness and evolutionary changes

BACKGROUND: Two-component systems (TCSs) are abundant prokaryotic signaling pathways, whose evolution is of particular importance because of their role in bacterial pathogenicity. Comparative genomics can provide important insights into the evolution of these genes, but inferences are dependent on the relatedness of the compared genomes. This study investigated the relationship between evolutionary distance and TCS evolution in myxobacterial genomes, of which there are several sequenced examples, of varying relatedness, and which encode large numbers of TCSs.METHODS: Myxobacterial TCS gene sets were compared, orthologues defined, and changes in TCS properties such as gene organisation, domain architecture and size identified.RESULTS: Genome relatedness/evolutionary distance was found to have a large effect on the apparent frequency of evolutionary events affecting TCS genes, but not on the relative dominance of different types of mutations. Large (≥1 gene) indels were the most common changes, often giving rise to gene organisation changes. Smaller indels were also common, sometimes changing domain architecture, and/or leading to pseudogene formation. Individuality of myxobacterial TCS gene sets seems primarily due to lineage specific gene loss. However, there is also evidence of extensive acquisition of genes by lateral transfer, with gene duplication also creating new TCS genes.CONCLUSIONS: This study provides catalogues of myxobacterial TCS gene sets and their orthology relationships, benchmarked against genome relatedness. It also provides insights into the relationship between evolutionary distance and the inference of TCS estudies of TCS evolution beyond the myxobacteriavolution, which may be important for studies of TCS evolutiThe online version of this articleon beyond the myxobacteria.</p

Facing others in pain : why context matters

Judging pain in another is challenging, largely because pain is a subjective phenomenon to which observers have no direct access. Despite this ambiguity, inferences often are made that can drive important clinical decisions, such as estimating another’s pain intensity, with significant implications for patient treatment and outcomes. This chapter focuses upon the influence of the context upon observer cognitive, emotional, and behavioral responses toward others in pain. In doing so, we consider context in its broadest form: characteristics of the patient/person in pain, the observer, and the situation, as well as elements of the reported pain experience, itself. Despite the increased understanding of and appreciation for the role of context in observer judgments, knowledge of how context, judgment, and treatment outcomes interact remains sketchy and in need of translational research. Such research is needed if we are to build our current base of knowledge and translate that knowledge into improved approaches to the assessment and treatment of patients in pain