Immunological resilience of a freshwater Indian mollusc during aestivation and starvation

• First report of variation in immune associated parameters in a commercially important mollusc during the phases of activity, aestivation and starvation.
• Pila globosa, an amphibian gastropod is capable of performing dual mode of respiration by gill and pulmonary sac in water and dry soil respectively.
• Significant alterations in total count and phagocytic efficiency of hemocytes were recorded in active, aestivated and starved specimens.
• Variation in the activities of phenoloxidase, superoxide dismutase, catalase, glutathione-S-transferase, acid and alkaline phosphatases were reported in the hemocytes and hemolymph of aestivated and starved P. globosa.

Freshwater snail, Pila globosa is an edible mollusc which bears commercial and ethnomedicinal significance. During environmental aridity, P. globosa aestivates deep into the soil for four to five months. We report comparative analyses of immune associated parameters in the hemocytes and hemolymph of P. globosa during activity, experimental aestivation, arousal and starvation. Hemocyte is a major cellular component of molluscan immune system. They are functionally involved in phagocytosis, cytotoxicity, antioxidative defence and enzyme mediated lysosomal pathogen degradation. Determination of the total hemocyte count, phagocytosis, generation of superoxide anion, nitric oxide and activities of phenoloxidase, superoxide dismutase, catalase, glutathione-S-transferase, phosphatases and protein content in the hemocytes and hemolymph were carried out during the mentioned phases of life process of P. globosa. Total count of hemocyte was recorded to be higher during aestivation, arousal and starvation in comparison to the phase of activity. Phagocytic response of hemocytes of P. globosa was highest during phase of activation. P. globosa exhibited high level of generation of superoxide anion and nitric oxide in the hemocytes during aestivation. Activity of phenoloxidase was recorded to be highest in the hemocytes and hemolymph among the starved individuals. Activities of superoxide dismutase and catalase were highest in the hemocytes of starved P. globosa. Glutathione-S-transferase activity was estimated to be high in the hemolymph and hemocytes of active specimens. Aestivation and starvation exhibited modulation in the activities of phosphatases in the hemocytes and hemolymph. Total content of protein of hemocytes was recorded to be low in the aestivated, aroused and starved P. globosa in comparison to the active ones. Nonuniform status of the immune parameters of hemocytes and hemolymph during activity, aestivation, arousal and starvation was indicative to a status of immunological resilience of the species to ensure adaptation during different physiological and environmental conditions.