AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 733-R739, Copyright © 1984 by American Physiological Society
Uptake of free amino acids by bacteria-free larvae of the sand dollar Dendraster excentricus
J. P. Davis and G. C. Stephens
Larvae of Dendraster excentricus were produced by collecting gametes and
carrying out fertilization under aseptic conditions. Since gametes are free
of bacteria in the gonad, bacteria-free (axenic) suspensions of larvae
result. Net rates of entry of 14 amino acids and the rate of production of
ammonia were simultaneously determined by high-performance liquid
chromatography. The net rates of uptake of neutral amino acids were an
order of magnitude greater than rates for basic and acidic amino acids.
Influx of 14C-labeled leucine, arginine, and glutamate accurately reflects
the net entry rate of these substrates. Uptake of amino acids by axenic
suspensions of larvae was compared with uptake by suspensions prepared
without aseptic precautions. There was no significant difference in net
uptake of the 14 amino acids or in the pattern of oxidation and
assimilation of [14C]leucine during short-term experiments of 4-h duration
or less.
