A comparative genomic analysis of the small heat shock proteins in XXXX and briggsae.

@entity23234 @entity2199
The small heat shock proteins (sHSPs) are a ubiquitous family of molecular chaperones. We have identified 18 sHSPs in the @entity2199 genome and 20 sHSPs in the @entity23234 genome. Analysis of phylogenetic relationships and evolutionary dynamics of the sHSPs in these two genomes reveals a very complex pattern of evolution. The sHSPs in @entity2199 and @entity23234 do not display clear orthologous relationships with other invertebrate sHSPs. But many sHSPs in @entity2199 have orthologs in @entity23234 . One group of sHSPs, the HSP16s, has a very unusual evolutionary history. Although there are a number of HSP16s in both the @entity2199 and @entity23234 genomes, none of the HSP16s display orthologous relationships across these two species. The HSP16s have an unusual gene pair structure and a complex evolutionary history shaped by gene duplication, gene conversion, and purifying selection. We found no evidence of recent positive selection acting on any of the sHSPs in @entity2199 or in @entity23234 . There is also no evidence of functional divergence within the pairs of orthologous @entity2199 and @entity23234 sHSPs. However, the evolutionary patterns do suggest that functional divergence has occurred between the sHSPs in @entity2199 and @entity23234 and the sHSPs in more distantly related invertebrates.
