Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1380

Esther (wajc)Lubzens, D. Rankevich, G. Kolodny, O. Gibson, A. Cohen, and M. Khayat; Physiological adaptations in the survival of rotifers (Brachionus plicatilis, O.F. Muller) at low temperatures. Hydrobiologia 313/314:175-183, 1995

Reprint

In File

Notes

The biology of the rotifer Brachionus plicatilis has been studied extensively in recent years, due to its importance in aquaculture. Today, the culture of several marine fish species relies completely on the daily production of live rotifers. In the present paper we explore the conditions that facilitate maintaining live rotifers for extensive periods at low temperatures. In addition to its possible contribution in providing reserve stocks for commercial application, these studies may be of ecological importance. They could explain some of the physiological adaptive mechanisms that are involved in the survival of rotifers under adverse environmental conditions. Experimental results showed relatively high survival rates (82-85%) in rotifers that were cultured at 25 degrees C and exposed later to -1 degrees C for 12-14 days. During this period, rotifers were kept without food and their media were not changed. The survival was found to depend on the rotifer culture conditions, prior to exposure to -1 degrees C. These included the type of food fed to rotifers (yeast or algae), the salinity in which they were cultured, and an essential acclimation period of 2-6 day at 4 degrees C or 10 degrees C. The acclimation period was associated with the synthesis of at least one specific protein and accumulation of lipids. Profiles of protein synthesis in rotifers incubated at 10 degrees C revealed a 94 kD protein, which did not appear in rotifers cultured at 25 or 37 degrees C. Immunoisolation, using a polyclonal antibody that was prepared against HSP60, revealed that this protein was synthesized in rotifers kept at 10, 25 or 37 degrees C. However, this antibody did not react with the 94 kD peptide. In addition, rotifers kept at 10 degrees C accumulated substantial amounts of lipids, including eicosapentaenoic acid (EPA), which is found in the algae fed to them. These results support the hypothesis of specific adaptations to survival at low temperatures during an acclimation period.