Peltier G, Thibault P
Département de Biologie, Service de Radioagronomie, Cen de Cardarache, B.P. No. 1, F-13115 Saint-Paul-lez-Durance, France.
Plant Physiol. 1985 Feb;77(2):281-4. doi: 10.1104/pp.77.2.281.
Glycolate and ammonia excretion plus oxygen exchanges were measured in the light in l-methionine-dl-sulfoximine treated air-grown Chlamydomonas reinhardii. At saturating CO(2) (between 600 and 700 microliters per liter CO(2)) neither glycolate nor ammonia were excreted, whereas at the CO(2) compensation concentration (<10 microliters per liter CO(2)) treated algae excreted both glycolate and ammonia at rates of 37 and 59 nanomoles per minute per milligram chlorophyll, respectively. From the excretion values we calculate the amount of O(2) consumed through the glycolate pathway. The calculated value was not significantly different from the component of O(2) uptake sensitive to CO(2) obtained from the difference between O(2) uptake of the CO(2) compensation point and at saturating CO(2). This component was about 40% of stationary O(2) uptake measured at the CO(2) compensation point. From these data we conclude that glyoxylate decarboxylation in air-grown Chlamydomonas represents a minor pathway of metabolism even in conditions where amino donors are deficient and that processes other than glycolate pathway are responsible for the O(2) uptake insensitive to CO(2).
在以l-蛋氨酸-dl-亚砜亚胺处理的、在空气中生长的莱茵衣藻中,于光照下测量了乙醇酸和氨的排泄以及氧气交换。在饱和CO₂(600至700微升/升CO₂之间)时,既不排泄乙醇酸也不排泄氨,而在CO₂补偿浓度(<10微升/升CO₂)下,处理过的藻类分别以每分钟每毫克叶绿素37和59纳摩尔的速率排泄乙醇酸和氨。根据排泄值,我们计算了通过乙醇酸途径消耗的O₂量。计算值与从CO₂补偿点和饱和CO₂时的O₂摄取差异中获得的对CO₂敏感的O₂摄取成分没有显著差异。该成分约占在CO₂补偿点测量的稳定O₂摄取的40%。从这些数据我们得出结论,即使在氨基供体不足的条件下,在空气中生长的莱茵衣藻中的乙醛酸脱羧作用也代表了一条次要的代谢途径,并且除乙醇酸途径之外的其他过程负责对CO₂不敏感的O₂摄取。