Biochemical and biophysical aspects of the tolerance of anhydrobiotic crustacean embryos to very high temperatures

1.Heat tolerance of dry cysts of the fairy shrimp Branchipus schaefferi and the brine shrimp, Artemia franciscana was studied using rapid (∼100 °C/min) and slow (∼4 °C/min) heating.2.Rapid heating caused much greater death than did slow, and we consider the possible causes.3.Although these primitive crustaceans are closely related, the major stress proteins of Artemia cysts (artemin and p26) were not detected in Branchipus cysts.4.The Arrhenius activation energy (Ea) for thermal killing of Branchipus cysts was found to be 5-fold higher than that of Artemia cysts over the range of 110-130 °C.5.These major differences in stress proteins and Ea are especially interesting because the thermal tolerance of both kinds of cysts is very similar.