Changes in respiratory enzyme activities during the early embryonic stages of the silkworm

Abstract Respiratory enzyme activities of the early embryonic stages of the silkworm were studied. The abundance of reduced cytochrome b 5 in the early embryonic stages of whole eggs was observed by the measurement of low temperature spectrum at −196°C. Spectrophotometric measurements using frozen whole eggs also revealed the presence of reduced cytochrome c after the decrease of oxygen uptake. Succinate-cytochrome c reductase activity of the particulate fraction is one per cent of cytochrome oxydase activity, and the change of activity paralleled the change in oxygen uptake of the eggs.