Protein metabolism, growth and pigmentation patterns during metamorphosis of plaice (Pleuronectes platessa) larvae

Protein metabolism, growth and pigmentation patterns were studied during th e process of metamorphosis in the plaice Pleuronectes platessa. Based on th e morphological and concurrent metabolic observations the process of metamo rphosis could be divided into three different phases: (I) premetamorphosis: from hatching to beginning of eye migration, (2) climaxmetamorphosis: eye migration, and (3) postmetamorphosis: the period immediately after completi on of eye migration. During premetamorphosis a gradual increase in DW was o bserved concomitant with constant concentrations of the nucleic acids RNA a nd DNA of the larvae. An increasing calcium concentration indicated the beg inning of skeleton ossification. Growth during this phase was primarily hyp erplastic as indicated by an increase in DNA per larva. Protein catabolism dominated, as indicated by an increase in the carbon to nitrogen ratio conc omitant with a decrease in nitrogen per unit DW. During climaxmetamorphosis an initial increase in the concentration of RNA was followed by a decrease in RNA, DNA and protein concentrations and the ratio of RNA to DNA. During postmetamorphosis growth of the larvae was again observed to be hyperplast ic. Calcium assimilation reached a plateau depicting complete ossification of the skeleton. Lipid catabolism dominated by the end of the metamorphosis process. Pigmentation appeared to develop in two marked phases. During pre metamorphosis larval melanophores and xanthophores dominated the pigmentati on pattern. The concentration of these chromatophores was markedly reduced at beginning of the eye migration process. During and immediately after eye migration the concentration of chromatophores increased significantly and the melanophores appeared to be of the adult type. (C) 1999 Elsevier Scienc e B.V. All rights reserved.