Annual changes in coelomocytes of four earthworm species: The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Abstract

Coelomocytes (extruded via dorsal pores of earthworms subjected to 5V electric shock) of adult Allolobophora chlorotica, Lumbricus terrestris, Dendrobaena veneta and Eisenia fetida consisted of species-specific proportions of hyaline amoebocytes, granular amoebocytes, and eleocytes. In all species a significant increase of granular amoebocytes with a parallel decrease of hyaline amoebocytes was recorded by the end of Spring and beginning of Summer, both in animals from the natural environment and in those kept in the laboratory at the room temperature. It indicates that coelomocyte proliferation/maturation is dependent mainly on the annual endogenous rhythm, which is relatively stable even at atypical ambient temperatures. During four successive seasons viability and functions (plastic adherence or neutral red pinocytosis) were recorded in coelomocytes of A. chlorotica assayed at various in vitro temperatures. In coelomocytes retrieved from animals freshly collected from their natural environment, coelomocyte activity was better at low temperatures (0 °C and 10 °C) during the Winter, while during other seasons (especially in the Summer) it was best at 22 °C. Such seasonal effects were abolished in coelomocytes from animals tested after one-month acclimation to the room temperature, as in all seasons cell functions were best at 22 °C. These observations indicate that earthworm coelomocytes can thermally adapt. This phenomenon was also recorded in L. terrestris, D. veneta and E. fetida. In conclusion, earthworm coelomocyte proliferation/maturation seems to be endogenously controlled while coelomocyte activity seems to be more plastic and subjected to thermal adaptation.