Adaptation of Drosophila enzymes to temperature—V. Heat shock effect on the malate dehydrogenase of Drosophila melanogaster

Abstract 1. 1. Drosophila melanogaster cMdh allozymic variants ( Mdh F , Mdh F/S , Mdh S ) were subjected to heat shock ( 33° C /30 min →40° C /30 min ). 2. 2. This stress increases differentially MDH specific activity, with the cMdh F strain showing greater response as compared with the cMdh S one; heterozygotes exhibited generally intermediate values. 3. 3. Correlative differences were also revealed for some catalytic properties ( V max , V max K max ratio, thermostability) of the cMDH; this is not true for the mMDH. 4. 4. The catalytic behavior of the enzyme is correlated with the differential survival of the cMdh variants, with the cMdh F showing again higher survival than the cMdh S one, a fact which seems to contribute to temperature adaptation of D. melanogaster .