. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 636 CLARK P. READ energy-requiring mechanisms might be involved. Preliminary experiments showed that treating the tissue with 2,4-dinitrophenol or subjecting it to complete anoxia resulted in a failure of galactose accumulation, the sugar in the tissue coming to concentration equilibrium with that in the external medium. Experiments were carried out to determine whether galactose inhibited amino acid uptake in such preparations. As with untreated tissues, galactose produced no significant inhibi- tion of cycloleucine uptake
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 636 CLARK P. READ energy-requiring mechanisms might be involved. Preliminary experiments showed that treating the tissue with 2,4-dinitrophenol or subjecting it to complete anoxia resulted in a failure of galactose accumulation, the sugar in the tissue coming to concentration equilibrium with that in the external medium. Experiments were carried out to determine whether galactose inhibited amino acid uptake in such preparations. As with untreated tissues, galactose produced no significant inhibi- tion of cycloleucine uptake in 2-minute incubations, but in 10-minute incubations galactose inhibited cycloleucine uptake. Similar results were obtained with tissues incubated under nitrogen. As will be seen in Table IV, when sodium in the incuba- tion medium was markedly reduced, the galactose effect was not observed with dinitrophenol-treated tissues. This is consistent with the idea that sodium is required for sugar absorption, as has been demonstrated with a number of other tissues (Crane, 1965).. 4 6 8 minutes preincubation FIGURE 5. Effect of duration of preincubation with galactose on subsequent uptake of cyclo- leucine. Samples were preincubated for time intervals shown with 5 mM galactose (closed circles) or without galactose (open circles). The uptake of cycloleucine-14C was then deter- mined in a 2-minute incubation in galactose-free medium. Cycloleucine at mM. V = minutes. Each point is an individual Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass.
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