Defence against oxidative stress in two species of land snails (Helix pomatia and Helix aspersa) subjected to estivation

Abstract

During summer, land snails are exposed to estivation/arousal cycles that imposes oxidative stress, but they exhibit different patterns of antioxidant defence. To test the ability of two related species, Helix pomatia and Helix aspersa, to modulate their antioxidant defence mechanism during estivation/arousal cycles, we examined activities of catalase and glutathione-related enzymes and concentrations of glutathione and thiobarbituric acid reactive substances (TBARS; as products of lipid peroxidation). In both species, estivation evoked changes in activity of total and selenium-dependent glutathione peroxidase (GPx), but did not affect activity of catalase, glutathione reductase, and glutathione transferase, and had no effect on concentration of glutathione. Activity of catalase in estivating snails, instead of the expected increase, showed a tendency to diminish. Extremely low activities of catalase in the foot were usually associated with extremely high activities of both forms of GPx. In conclusion, maintenance of relatively high activities of the antioxidant enzymes and accumulation of glutathione, resulting in a low and stable concentration of TBARS, plays an important role in scavenging oxygen free radicals from the organism of both species.

Antioxidant and molecular chaperone defenses during estivation and arousal in the South American apple-snailPomacea canaliculata

“…The kidney and the foot had generally lower TBARS levels, but both showed increased damage during estivation, and a recovery at 24h of arousal, which indicates here the operation of effective antioxidant defences during arousal. Comparisons of TBARS levels between organs in both the freshwater P. canaliculata as well as in the terrestrial gastropods Otala lactea (Hermes-Lima and Storey, 1995), Helix aspersa (Ramos-Vasconcelos and Hermes-Lima, 2003) and Helix pomatia (Nowakowska et al, 2011) showed lower values in the foot than in the midgut gland. Also, Nowakowska et al (Nowakowska et al, 2011) found even lower levels in the kidney than in the foot of H. aspersa.…”

“…Hence the high concentrations of glutathione observed before the hypometabolic situation and the recovery of the control levels after it, fit GSH changes into the first of the proposed strategies (Storey, 1996). Oxidation of GSH is a phylogenetically spread and efficient mechanism of antioxidant defense that is important in terrestrial gastropods, both during and after hypometabolic situations (Hermes-Lima and Storey, 1995;Ramos-Vasconcelos et al, 2005;Nowakowska et al, 2009;Nowakowska et al, 2011). In the latter gastropods, as well as in P. canaliculata, GSH concentration was higher in the midgut gland than in the foot (Hermes-Lima and Storey, 1995;Ramos-Vasconcelos and Hermes-Lima, 2003;Nowakowska et al, 2009) (Fig.1D), and the sustained levels observed during the activity-estivation cycle indicate that GSH is an effective antioxidant defence mechanism in the midgut gland, avoiding the elevation of TBARS levels in the cycle.…”

“…The role of antioxidant defences during water shortage has received special attention in terrestrial gastropods (Hermes-Lima et al, 1998;Hermes-Lima and Zenteno-Savin, 2002;RamosVasconcelos et al, 2005;Nowakowska et al, 2009;Nowakowska et al, 2010;Nowakowska et al, 2011) and has also been studied in some aquatic gastropods (Ferreira et al, 2003;Giraud-Billoud et al, 2011). In general, terrestrial gastropods have stable levels of antioxidant defences such as superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) (Hermes-Lima and Storey, 1995;Nowakowska et al, 2009;Nowakowska et al, 2011).…”

“…In general, terrestrial gastropods have stable levels of antioxidant defences such as superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) (Hermes-Lima and Storey, 1995;Nowakowska et al, 2009;Nowakowska et al, 2011).…”

“…In the present study, the changes in the antioxidant profile (non-enzymatic and enzymatic defences) have been studied in the midgut gland, the kidney and the foot, since determinations in these organs would allow comparison with preceding studies in other gastropods (Hermes-Lima and Storey, 1995;Hermes-Lima et al, 1998;RamosVasconcelos and Hermes-Lima, 2003;Ramos-Vasconcelos et al, 2005;Nowakowska et al, 2009;Nowakowska et al, 2011). Furthermore, the constitutively expressed heat shock cognate protein 70 (Hsc70), recently characterized in P. canaliculata (Zheng et al, 2012), the inducible Hsp70 form and Hsp90 have been studied, as additional defense mechanisms that may be involved during the activity-estivation cycle in this apple snail.…”