Meeting Abstract
The perciform suborder Notothenioidae is comprised of Antarctic and sub-Antarctic fishes, several of which have lost their ability to rapidly upregulate major heat shock proteins (HSPs) in response to stress. Rather, inducible HSPs such as the hsp70 and hsp90 families are constitutively expressed under normal environmental conditions and do not upregulate following oxidative damage to the cell. While it was initially suggested that the constitutive expression of HSPs resulted from constant cold-denaturation of the proteome, there is evidence to suggest that the trait is not environmentally controlled. Therefore, it is plausible that the trait is attributed to functional alterations to regulatory elements of the inducible heat shock response (HSR). In order to identify genomic divergence within Notothenioidae that may confer the loss of an inducible HSR, we sequenced the complete coding region of the transcription factor HSF1 and cis-acting heat shock element (HSE) motifs across the genomes of two members of the notothenid family, the Antarctic notothen Trematomus bernacchii, which has lost induction of the HSR, and a temperate notothen exhibiting a classical HSR, Notothenia angustata. We have compared the degree of conservation between HSF1 orthologs in T. bernacchii and N. angustata to shed light on differences in the regulation of inducible HSPs among notothens. These results, in addition to preliminary data derived from HSE sequencing, provide mechanistic insight into how the regulation of inducible proteins is modified to confer constitutive expression or activation during adaptation.
