Changes in the levels of nucleic acid, protein, total free amino acid and glycogen, and activity of acid phosphatase in the eggs, during normal embryonic development of the rice moth, Corcyra cephalonica, stainton (Lepidoptera: Pyralidae)

Abstract

DNA, RNA, protein, total free amino acid and glycogen levels, and acid phosphatase activity were determined in the eggs of the rice moth, Corcyra cephalonica during normal embryonic development. The DNA levels remain lower and relatively constant in the eggs of 6, 12 and 24 h of age, while in the eggs of older age groups, i.e. 36, 48, 60 and 72 h, a marked increase in the DNA levels occurs. The RNA content shows a significant rise up to the 36 h stage, then its level declines sharply. The RNA DNA ratio increases markedly from the 6 h stage and reaches to its maximum in the eggs at the 36 h stage, indicating increase in the degree of synthetic activity that takes place during such period of embryonic development. In the later phases this ratio declines rapidly and reaches to a minimum level in the eggs of 72 h of age. The level of protein is highest while that of total free amino acid is lowest in the eggs of 6 h of age. In the 12-h-old eggs, the protein level declines markedly with a rapid increase in total free amino acid concentration. Periods beyond the 12 h stage are represented by slight fluctuations in the amount of both these constituents. The age-related rise and fall in glycogen levels are similar to that of RNA. The activity of acid phosphatase is minimum in the 6-h-old eggs and reaches to a peak level in the eggs of 72 h of age following a sigmoid pattern.