UPTAKE AND UTILIZATION OF C-14 GLYCINE BY EMBRYOS OF SEBASTES-MELANOPS

The ability of embryos of the viviparous scorpaenid Sebastes melanops to take up nutrients from an exogenous substrate was demonstrated by incubating embryos at various stages of development (18-30 days after fertilization) in C-14-labeled glycine for 24 h. Uptake was highest for embryos at the latest stages (28-30 days) and increased at a linear rate during the incubation period. Nutrient uptake was not time dependent in embryos at the early stages (18-22 days). Nutrient utilization by S. melanops embryos was measured by the oxidation of C-14-labeled glycine to (CO2)-C-14. The amount of respired (CO2)-C-14 by the oldest embryos increased significantly at a linear rate over the 24 h incubation period. There was no evidence of nutrient utilization by the youngest embryos. The developmental changes we observed in the uptake and utilization of exogenous glycine are supported by our previous findings that the oldest embryos have fully developed mouths and guts, and require additional nutrition from intraovarian sources at this stage of development.