Acclimatory changes in protein and nucleic acid contents of liver, muscle, and ovary of Singi fish (Heteropneustes fossilis Bloch) of two phases of reproductive cycle at different temperatures.

The variation of environmental temperature has significant effect on the metabolism of liver, muscle, and ovary of female Singi fish (non-vitellogenic and vitellogenic). Acclimation of Singi fish at 15, 25, and 30 degrees C for 30 d resulted in reduction of hepatosomatic index with the rise of temperature. The protein content of liver increased at 30 degrees C in both non-vitellogenic and vitellogenic fish. The liver RNA, however, showed a reduction with the rise of temperature at nonvitellogenic stage, but it increased at higher temperature (25 or 30 degrees C) at vitellogenic stage. The protein content of muscle enhanced with the rise of temperature in both non-vitellogenic and vitellogenic fish. The muscle RNA, however, remained unchanged at different acclimatory temperature. The gonadosomatic index increased after acclimation at 30 degrees C both at non-vitellogenic and vitellogenic stage. The protein content of ovary increased at these 2 stages with the rise of temperature from 15 to 25 degrees C and from 25 to 30 degrees C but the ovarian RNA changed in opposite direction (reduction) under these conditions. The DNA content of liver of non-vitellogenic fish and of muscle of both non-vitellogenic and vitellogenic fish did not alter with the change in acclimation temperature. The liver DNA showed a reduction at vitellogenic stage with the rise of temperature. The DNA content of ovary increased at non-vitellogenic stage and decreased at vitellogenic stage after acclimation at 30 degrees C.