Changes in RNA,
DNA and protein contents of laboratory-reared Japanese flounder Paralichthys
olivaceus during metamorphosis and settlement
W.-S. Gwak, M. Tanaka-2002
Fisheries Science, 68(1): 27-33
Abstract:
By means of biochemical analyses on an
individual basis, developmental changes in nutritional status during
metamorphosis and settlement were examined in laboratory-reared Japanese
flounder Paralichthys olivaceus. Although whole-body DNA content
increased gradually throughout metamorphosis and settlement, the RNA content
generally remained constant during the late metamorphosing stage and
postmetamorphic phase. Subsequently, the RNA : DNA ratio decreased
drastically from the late metamorphosing stage to the postmetamorphic phase
following a continuous elevation in the ratio during early and
mid-metamorphosing stages. The changes in protein content coincided well
with RNA content. The protein : DNA ratio also peaked at the postmetamorphic
phase and decreased for several days thereafter, suggesting the occurrence
of hypertrophy until the postmetamorphic phase, followed by hyperplasia. It
is speculated that the nutritional status of Japanese flounder becomes lower
when associated with entry to the final phase of metamorphosis and/or
settlement at which feeding habits drastically change. Poor nutritional
status of the newly settled juveniles may increase their vulnerability to
predators in the nursery ground.
(The University of Georgia Marine
Institute, Sapelo Island, GA 31327, USA, Tel: 81-75-753-6220. Fax: 81-75-753-6229. Email: masatnk@kais.kyoto-u.ac.jp)