Protein and Nucleic Acid Changes during Early Developmental Stages of Cresthead Flounder

Abstract

Protein, DNA and RNA contents, together with the growth rates of body length and dry weight were measured for the cresthead flounder Limanda schrenki, during one month after hatching. The larvae showed no remarkable changes of external morphology in the first two weeks, started metamorphosis in the third week, and then into benthic phase in the fourth week. The maximum value of growth rates of body length and dry weight were observed in the second week. The changes in increasing rate of the protein showed the same tendency as that of dry weight. The values of protein increasing rate in the first week was almost equal to the growth rate of dry weight, while in the second week the former was lower than the latter. This result may be caused by the fact that some nonprotein materials accumulated in the second week. The pattern of changes in DNA content tended to be similar to changes in RNA content. The increasing rates of DNA and RNA were highest in the second week, and minimum rates were seen in the third week. Protein/DNA ratio indicated cell size, decreased rapidly during the first two weeks, whereas only in the third week did the ratio increase. The result indicated that cell proliferation occurred actively in the first two weeks and cell enlargement was taking place primarily in the third week. In the fourth week, there is less significant difference among the increasing rate of dry weight, protein, DNA and RNA. © 1986, The Japanese Society of Fisheries Science. All rights reserved.