Photosynthetic products of division synchronized cultures of euglena.
Rates and products of photosynthetic (14)CO(2) fixation by division synchronized cultures of Euglena gracilis strain Z were determined over the cycle. Rate of (14)CO(2) fixation doubled in a continuous manner throughout the light phase followed by a slight reduction of photosynthetic capacity in the dark phase. Greater (14)C incorporation into the nucleic acid-polysaccharide fraction occurred with mature cells. Products of (14)CO(2) fixation varied markedly over the cycle: although with mature cells (14)C-labeled sucrose was not detected, with dividing cells this was the main sugar labeled; in young cells (14)C maltose was formed. Cells removed at end of dark phase accumulated (14)C in glycolate, whereas at other stages over the cycle less (14)C was present in glycolate, and this was accompanied by a rapid incorporation of (14)C into glycine and serine. Glycerate was an early and major product of photosynthesis with cells at the mature stage of the cycle.Changes in ribulose 1,5-diphosphate carboxylase activity paralleled changes in photosynthetic rate, but activity was not great enough to account for the observed rates of CO(2) fixation at most stages of the division cycle investigated.
Codd
G A
GA
Postgraduate School of Studies in Biological Sciences, University of Bradford, Bradford, Yorkshire BD7 1DP, England.
Merrett
M J
MJ