CHARACTERISTICS OF INFLUX AND NET FLUX OF AMINO ACIDS INMYTILUS CALIFORNIANUS

Abstract

1. Intact mussels and an in vitro preparation of isolated gill tissue were employed to study characteristics of the influx and net flux of amino acids in Mytilus californianus. 2. The kinetics of influx of 14C-labelled amino acids were complicated by the presence of a rapidly labelled extracellular compartment. 3. Correction of influx data for the extracellular compartment revealed influx of 14C-cycloleucine and 14C-glycine to be mediated by a transport mechanism adequately described by Michaelis-Menten kinetics. Passive diffusion plays no significant role in influx. 4. Influx and net flux of glycine into intact Mytilus were examined. From high concentrations (greater than 20 micronM) the influx of 14C-glycine was equivalent to the net influx of primary amine as determined by fluorescamine. At low ambient concentrations (greater than 20 micronM), influx of 14C-glycine occurred more rapidly than net influx as determined by fluorescamine. The data suggest that influx of labelled substrate is accompanied by efflux of unknown primary amine(s). In the absence of labelled substrate, efflux continues until a steady-state concentration of 2-5 micronM in the medium is achieved.5. The rate of influx of 14C-cycloleucine into isolated gill tissue, and the concentration gradient which can be developed by gill tissue are reduced when sodium is replaced in the medium. 6. The efflux of primary amines from isolated gill tissue is stimulated by the replacement of sodium in the medium with choline. 7. The data are consistent with a sodium-coupled mechanism for the transport of amino acid into gill tissue. However, energetic considerations cast doubt on the adequacy of such a mechanism to account fully for the observed trans-epidermal transport.

Amino-acid uptake by mussels,Mytilus edulis, from natural sea water in a flow-through system

“…Experimental approaches included employment of isolated gill tissue (Bamford & Gingles, 1974;Bamforcl & McCrea, 1975;Stewart & Bamford, 1975Wright et al, 1975;Bamford & Campbell, 1976;Stewart, 1977Stewart, , 1978Stewart, , 1981Wright & Stephens, 1977;Gomme, 1982;Wright, 1982;Wright et al, 1984) and whole animals {Anderson & Bedford, 1973;P6quinat, 1973;Crowe et al, 1977;Stewart, 1977Stewart, , 1981Manahan et al, 1982;Jergensen, 1982Jergensen, , 1983Wright, 1982;. Uptake of DOM in bivalve larvae has been studied by Fankboner & De Burgh (1978), Manahan (1983a, b), Manahan & Richardson (1983), and Manahan et al…”

A Time Series of BV photometry and H{alpha} Emission Fluxes of the Eclipsing Binary VV Cep

“…In VV Cep, Hα emission is especially prominent, with peak fluxes of ∼10-30 times that of the (M star) continuum. This Hα emission exhibits radial velocity behaviour opposite to that of the M supergiant, implying a source near the hot companion (Wright 1977). Even though this emission declines sharply for higher Balmer lines, at times Balmer emission remains visible from levels up to n ∼ 16.…”

Autoradiographic analysis of amino acid uptake by the gill ofMytilus

“…In this and in the other experiments reported here, all counts were corrected for variable quench by using an external standard. Previous studies indicated the advisability of correcting uptake data for the presence of exogenous radioactivity left associated with the tissue after rinsing and blotting (Wright and Stephens 1977). In the present study, uptake data were corrected by subtracting an average value for the inulin space of a 1-cm gill disc, determined previously (Wright 1979).…”

“…The uptake of radioactively labelled amino acids into isolated gills was measured as described previously (Wright and Stephens 1977). Briefly, demibranchs were dissected from animals and discs of tissue cut from the isolated tissue using a 1 cm stainless steel punch.…”