Utilization of Glucose by Astasia longa*

Abstract

SYNOPSIS. A mutant strain of Astasia longa utilized glucose for growth whereas the parent (J) strain did not. The optimal pH for growth of the mutant with glucose (sole carbon source) was near neutrality; the optimal glucose concentration 0.02 M. Cell‐free extracts or cell homogenates produced C14O2 when incubated in the presence of C14‐labeled glucose. On the other hand, after incubation with C14‐labeled glucose, intact parent cells and their respiratory CO2 showed no radioactivity while the mutant‐strain cells and CO2 produced were active. Dissimilation of glucose‐1‐C14 and glucose‐6‐C14 yielded the same amount of radioactivity in metabolic CO2 in cell‐free extracts of both strains. Of five enzymes assayed, hexokinase, phosphoglucomutase, and lactic dehydrogenase were present whereas glucose‐6‐PO4 dehydrogenase and glucose dehydrogenase were absent in cell homogenates of both strains. Presumably these two strains of A. longa differ in permeability of the plasma membrane. Further tracer and enzyme studies indicated that the Embden‐Meyerhof scheme is the principal pathway of glucose catabolism; the hexose mono‐phosphate shunt and the direct oxidative pathway were either not operating or quantitatively insignificant.

A Physiological Comparison of the Symbiotic AlgaPlatymonas Convolutaeand its Free-Living Relatives

“…The original cultures of P. convolutae do not utilize exogenous glucose and as they store starch and contain hexokinase this inability to utilize glucose must be because the molecule cannot enter the cell. The presence of a barrier to glucose entry has been described in colourless flagellates by Barry (1962) in Astasia longa and by Chapman, Cirillo & Jahn (1965) in Polytoma obtusum. Barry obtained a mutant strain of Astasia by X-ray treatment that was able to utilize glucose, and similarly in the present work a strain of P. convolutae has been obtained by selection in a medium of high glucose concentration that will utilize glucose.…”

Effect of Light on Glucose Utilization by Euglena gracilis

“…Cells were grown in one of the media described in Table I, in the dark or in the light, and the cell density was measured every day. Values in Table II (Table II, lines 4 and 5), then, after 1 week of incubation they show a rate of division higher than that of phototrophic cultures. However, they never reach the cell density of cultures incubated in the dark.…”