EXCRETION OF GLYCOLATE, MESOTARTRATE AND ISOCITRATE LACTONE BY SYNCHRONIZED CULTURES OF ANKISTRODESMUS-BRAUNII
EXCRETION OF GLYCOLATE, MESOTARTRATE AND ISOCITRATE LACTONE BY SYNCHRONIZED CULTURES OF ANKISTRODESMUS-BRAUNII
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DOI：
10.1104/pp.46.3.377
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发表时间：
1970-01-01
期刊：
影响因子：
7.4
通讯作者：
TOLBERT, NE
中科院分区：
文献类型：
--
作者：
CHANG, WH;TOLBERT, NE
通过同步培养的布朗氏ankistrodesmus固定14co2在年轻生长细胞中最高，在成熟细胞中最低，在分裂细胞中最低。在光合作用过程中，碳的排泄量也遵循同样的趋势。在生长末期，经过16小时光照期的10小时后，细胞排出了固定为一种产物乙醇酸的近35%的14c。当在光照下测试从黑暗阶段分裂出来的细胞时，其分泌的乙醇酸- 14c仅为年轻生长细胞的4%。分裂的细胞也会分泌出与乙醇酸一样多的中酒石酸，以及一些异柠檬酸内酯和一种未识别的酸。在细胞内没有发现大量的这些排出的酸。目前有分离和鉴定排泄酸的方法。用14c标记的藻类，研究表明乙醇酸的排泄是光依赖性的，并被1,1-二甲基-3-（对氯苯）尿素抑制。标记的中酒石酸盐、异柠檬酸内酯和一种未知的酸（但不是乙醇酸）也在黑暗中排泄。排出的中酒石酸盐主要是羧基标记的，即使经过长时间的14co2固定。由于已知乙醇酸是均匀标记的，因此乙醇酸不可能是羧基标记的中酒石酸盐的前体。乙醇酸、中酒石酸和异柠檬酸内酯的特定排泄原因尚不清楚，但藻类对这三种酸的代谢可能是有限的，每一种酸都可以通过脱水形成二酯或内酯。在这种情况下，排出的是异柠檬酸内酯而不是游离酸。
Fixation of14CO2by synchronized cultures ofAnkistrodesmus brauniiwas highest for young growing cells, low for mature cells, and lowest for dividing cells. The amount of14C excreted during photosynthesis followed the same trend. Cells at the end of the growing phase, after 10 hours of a 16-hour light phase, excreted nearly 35% of the total14C fixed as one product, glycolate. Dividing cells from the dark phase, when tested in the light, excreted only 4% as much glycolate-14C as the young growing cells. Dividing cells also excreted as much mesotartrate as glycolate and also some isocitrate lactone and an unidentified acid. None of these excreted acids were found inside the cells in significant amounts. Methods for isolation and identification of the excreted acids are present. With14C-labeled algae, it was shown that the excretion of glycolate was light-dependent and inhibited by 1,1-dimethyl-3-(p-chlorophenyl) urea. The excretion of labeled mesotartrate, isocitrate lactone, and an unknown acid, but not glycolate, also occurred in the dark. The excreted mesotartrate was predominantly carboxyl-labeled even after long periods of14CO2fixation. Since glycolate is known to be uniformly labeled, glycolate could not be the precursor of the carboxyl-labeled mesotartrate. The reason for the specific excretion of glycolate, mesotartrate, and isocitrate lactone is not known, but the metabolism of all three acids by the algae may be limited and each can form dilactides or lactones by dehydration. In this context isocitrate lactone was excreted rather than the free acid.