Characterisation of the warm acclimated protein gene (wap65) in the Antarctic plunderfish (Harpagifer antarcticus)

Abstract

Physiological adaptation to increased environmental temperatures has been studied experimentally in a number of fish species, with the up-regulation of several genes identified as being associated with the process, such as the warm-acclimated protein (wap-65). This article describes the cloning and characterisation of the wap65-2 gene from the Antarctic plunderfish (Harpagifer antarcticus). The transcriptional expression of this gene in response to elevated seawater temperatures over a time course series is presented. Initially there is strong down regulation of this gene to a maximum of 40 fold within 4 hours, followed by recovery to almost control levels within 48 hours, indicating that this gene does not play a role in the potential temperature adaptation of H. antarcticus. WAP65

Lack of an HSP70 heat shock response in two Antarctic marine invertebrates

“…The shape of the 2°C graphs mirror the results of a 6°C 48 hour time course experiment in Harpagifer antarcticus for both HSP70 gene family members and the warm acclimated protein (WAP65) (Clark et al, 2007;Clark and Burns, 2007). It has been proposed that initial down-regulation of certain genes is due to the initial "shock" response followed by a return to equilibrium as these animals acclimate.…”

“…To obtain a crude estimate of the relative expression levels of each of the HSP genes in each organism the genes were assayed using PCR and gel electrophoresis with ethidium bromide staining in a set of control animals (data not shown). Actin expression, as expected, produced a strong signal in each species, but there was no discernable expression of the HSP family members either in P. gibber constitutive expression of HSP70, HSC70 and GRP78 (Place and Hofmann, 2005;Clark et al, 2007Clark et al, , 2008a. This is thought to be due to an enhanced requirement for chaperone proteins to help with the problems of protein folding at low temperatures (Place et al, 2004).…”

“…The more species surveyed, the more complex the picture. There is now data on several fish species (Place and Hofmann, 2005;Clark et al, 2007), a filter feeding bivalve mollusc and a grazing gastropod mollusc (Clark et al, 2008a). We have now added to this with data for a detritivore and a carnivore/detritivore.…”

“…Confidence Intervals with Q-PCR experiments (discussed in more detail in Clark et al, 2007). Therefore biomarker gene expression levels must show a strong signal above background variation in order for valid conclusions to be drawn about perturbation effects.…”

“…The latter is particularly pertinent, given that with the exception of Hydra oligactis (Bosch et al, 1988), the only species that have been shown to lack the classical heat shock response are an Antarctic ciliate (La Terza et al 2001) and two Antarctic notothenioid fish (Carpenter and Hofmann, 2000;Hofmann et al, 2000;Place and Hofmann, 2005;Clark et al, 2007). In addition two Antarctic molluscs Laternula elliptica (bivalve) and Nacella concinna (gastropod) have a demonstrable heat shock response, but at threshold levels (10-15°C) that are incompatible with moderating any deleterious effects from elevated Polar sea water temperatures (Clark et al, 2008a).…”