The Effect of Temperature Stress on Development and Heat-shock Protein Expression in Larval Green Sturgeon (Acipenser mirostris)

Abstract

Water temperature is an important environmental variable influencing the distribution and health of coldwater fishes such as the green sturgeon, Acipenser medirostris. In this study, we investigated if larval sturgeon were able to tolerate or recover from acute, non-lethal temperature stress that commonly causes deformed notochords, and sought to identify the role of heat-shock proteins (hsp) in stress tolerance. The hsp response is one of the most important cellular mechanisms to prevent the damaging effects of thermal cellular stress, and differences in the ability to over-express hsps during stressful conditions may be associated with an organism's vulnerability and the extent of thermal injury. In this study, newly hatched larvae were maintained at 17°C (control), or exposed to (a) 26°C for 3 d then maintained at 17°C until yolk-sac absorption or (b) 26°C until yolk-sac absorption. Individuals with deformed notochords were counted, and hsp60, 72, 78 and 89 were analyzed in both normal and deformed larvae by western blotting. Approximately 33% of fish developed curved notochords within the first 3 d of exposure to 26°C. After transfer to cool water 16.5% showed deformities at stage 45, suggesting a significant number of larvae had recovered. Hsp levels remained elevated for at least 9 days after termination of heat-exposure. Overall, percentage of deformed larvae, and hsp72/hsp78 levels were highest in fish continuously exposed to 26°C until yolk-sac absorption. Deformed individuals had significantly higher expression levels of hsp72 and hsp78, and lower hsp60 levels than normal larvae. We conclude that expression of hsp72 and hsp78 and potentially hsp60 are linked to phenotypic variation in the response and vulnerability of green sturgeon larvae to thermal stress.

Cellular responses to temperature stress in steelhead trout (Onchorynchus mykiss) parr with different rearing histories

“…There is evidence that hsp70 proteins in some fish species are relatively stable; for example, cutthroat trout (O. clarki) erythrocytes and gill tissue maintained high levels of hsp70 for at least 5 days after a 2-h heat-shock at 22.4°C (from 6.2°C; Bierkens 2000). In addition, hsp70 levels in green sturgeon larvae remained elevated for at least 6 days after a 3-day heat-shock at 26°C (Werner et al 2006). This is in contrast to mammalian cells, where hsp70 expression generally returns to normal after 24-h (Feige et al 1996).…”

Effects of nutritional deprivation on juvenile green sturgeon growth and thermal tolerance

“…Though effects of nutritional status on the cellular HSP70 protein response to warming had not previously been assessed for green sturgeon, the HSP70 response to warming has been measured in larval (Werner et al 2007;Silvestre et al 2010;Linares-Casenave et al 2013), juvenile (Allen et al 2006) and 2 kg (Wang et al 2013) green sturgeon. Studies generally exposed sturgeon to temperatures of 24 to 28°C, and all showed significant increases in HSP70 protein levels with high temperature.…”

Assessment of the accuracy of physiological blood indicators for the evaluation of stress, health status and welfare in Siberian sturgeon (Acipenser baerii) subject to chronic heat stress and dietary supplementation

“…The same trend was found in the literature with various sturgeon species and tissues (see Table 2 for details on species, tissues and HSP). HSP protein levels increase as a consequence of heat stress (Allen et al 2006;Deng et al 2009;Han et al 2012;LinaresCasenave et al 2013;Silvestre et al 2010;Wang et al 2013;Werner et al 2007;Zheng et al 2015), acute cold stress, air exposure (Wang et al 2013), and contamination (Keyvanshokooh et al 2009), but not during salinity acclimation (Sardella and Kültz 2009). Hsp mRNA expression increases with high stocking density or after an acute hypoxic stress (Ni et al 2014).…”