Intraspecific variation in cellular and biochemical heat response strategies of Mediterranean Xeropicta derbentina [Pulmonata, Hygromiidae]

• Published in: PloS one 2014-01, Vol.9 (1), p.e86613
• Main Authors: Troschinski, Sandra, Di Lellis, Maddalena A, Sereda, Sergej, Hauffe, Torsten, Wilke, Thomas, Triebskorn, Rita, Köhler, Heinz-R
• Format: Article
• Language: English
• Subjects: Acclimatization - genetics; Acclimatization - physiology; Adaptation; Analysis; Animals; Base Sequence; Biochemistry; Biology; Calcium; Cellular structure; Cytochrome; Cytochrome-c oxidase; Desiccants; Desiccation; DNA Primers - genetics; Drosophila melanogaster; Drying; Earth Sciences; Electron Transport Complex IV - genetics; Energy Metabolism - physiology; Enzymes; Evolution; Exposure; France; Genetic diversity; Genetic engineering; Genetic research; Genetic Variation; Heat; Heat resistance; Heat shock proteins; Heat stress; Heat tolerance; Helicidae; Hepatopancreas; Hepatopancreas - physiology; Hot Temperature; HSP70 Heat-Shock Proteins - metabolism; Hsp70 protein; Insects; Laboratories; Mitochondria; Molecular Sequence Data; Mollusks; Morphology; Overheating; Oxidases; Physiological aspects; Physiology; Population; Population structure; Population studies; Populations; Proteins; Regression Analysis; Sequence Analysis, DNA; Snails; Snails - genetics; Snails - physiology; Species Specificity; Stress response; Survival; Terrestrial environments; Thermal resistance; Vegetation
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0086613

Dry and hot environments challenge the survival of terrestrial snails. To minimize overheating and desiccation, physiological and biochemical adaptations are of high importance for these animals. In the present study, seven populations of the Mediterranean land snail species Xeropicta derbentina were sampled from their natural habitat in order to investigate the intraspecific variation of cellular and biochemical mechanisms, which are assigned to contribute to heat resistance. Furthermore, we tested whether genetic parameters are correlated with these physiological heat stress response patterns. Specimens of each population were individually exposed to elevated temperatures (25 to 52°C) for 8 h in the laboratory. After exposure, the health condition of the snails' hepatopancreas was examined by means of qualitative description and semi-quantitative assessment of histopathological effects. In addition, the heat-shock protein 70 level (Hsp70) was determined. Generally, calcium cells of the hepatopancreas were more heat resistant than digestive cells - this phenomenon was associated with elevated Hsp70 levels at 40°C.We observed considerable variation in the snails' heat response strategy: Individuals from three populations invested much energy in producing a highly elevated Hsp70 level, whereas three other populations invested energy in moderate stress protein levels - both strategies were in association with cellular functionality. Furthermore, one population kept cellular condition stable despite a low Hsp70 level until 40°C exposure, whereas prominent cellular reactions were observed above this thermal limit. Genetic diversity (mitochondrial cytochrome c oxidase subunit I gene) within populations was low. Nevertheless, when using genetic indices as explanatory variables in a multivariate regression tree (MRT) analysis, population structure explained mean differences in cellular and biochemical heat stress responses, especially in the group exposed to 40°C. Our study showed that, even in similar habitats within a close range, populations of the same species use different stress response strategies that all rendered survival possible.