Saleem Mustafa

Influence of Maturation on the Concentrations of RNA and DNA in the flesh of the Catfish Clarias batrachus

Abstract Maturation of catfish Clarias batrachus (Linn.) was accompanied by steady increase in the concentration of DNA and decrease in that of RNA in the skeletal muscle. The apparent rise in DNA concentration could reflect the depletion of body tissues rather than actual synthesis.

Air breathing ofColisa fasciata (Schneider)

The rates of air breathing ofColisa fasciata were recorded at 5°; C interval over a temperature range of 20–40° C. The air breathing rate increased with the temperature. This was attributed to increase in the metabolic rate and the muscular activity (general restlessness), both of which make heavy demands of oxygen. Coupled with these, the decline of oxygen-holding capacity of the water at higher temperatures leave the fish with no option but to increase its dependence on the atmospheric oxygen and hence the rise in the air breathing rate. Increase in the temperature was also characterised by decrease in the time of asphyxiation when the fish was prevented from coming to the surface and gulping the air.

Chemical Analysis of Internal Environmental Response of Carp Puntius stigma to DDT

Exposure of Puntius stigma to sublethal dose of DDT (0.05 ppm) for 15 days decreased the liver concentrations of protein and DNA from 65 +/- 0.91 to 63 +/- 0.78 mg/100 mg and 669 +/- 17 to 575 +/- 14 micrograms/100 mg, respectively whereas RNA increased from 8214 +/- 318 to 8929 +/- 209 micrograms/100 mg. Biotransformation products of this hydrocarbon interfered in the pathways of protein biosynthesis and induced proteolysis in hepatic tissues. The resulting changes were explained in the light of hypertrophication of liver parenchyma and inter-relationships of chemical constituents.