Paul John H., Kang Jordan B., Tabita F Robert
University of South Florida, 140 Seventh Avenue S., St. Petersburg, FL 33701, U.S.A.
Mar Biotechnol (NY). 2000 Sep;2(5):429-436. doi: 10.1007/s101260000016.
Diel patterns of rbcL transcription, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) activity, and whole cell carbon fixation were compared in the marine cyanobacterium Synechococcus PCC7002 and the chromophytic prymnesiophyte Pavlova gyrans. Both organisms were grown on a 12:12 light-dark cycle, with the light period starting at 0700. Strong diel patterns in these three aspects of carbon fixation occurred in both organisms, with maximal levels in the light period and minima in the dark. In Synechococcus, maximal rbcL transcript abundance occurred at noon and was followed by rapid disappearance. RubisCO enzyme activity and whole cell carbon fixation were elevated at 1600, and they disappeared over the next 8 hours. In contrast, in Pavlova, rbcL transcript abundance was maximal at 1600, and it was maintained at 66% of this level into the dark period (2000). Whole cell carbon fixation and RubisCO activity were elevated into the dark period (at 2000), being 77% and 81%, respectively, of the maximum. A similar diel pattern of cyanobacterial-like and chromophyte-like rbcL transcription has been observed in natural phytoplankton populations. These studies suggest that chromophytes are more adapted to take advantage of carbon fixation late in the day than cyanophytes.
对海洋蓝细菌聚球藻PCC7002和色素植物定鞭藻陀螺拟球藻中1,5 - 二磷酸核酮糖羧化酶/加氧酶（RubisCO）活性、rbcL转录以及全细胞碳固定的日变化模式进行了比较。两种生物均在12:12的光暗周期下培养，光照期于0700开始。这两种生物在碳固定的这三个方面均出现了强烈的日变化模式，光照期达到最高水平，黑暗期降至最低。在聚球藻中，rbcL转录本丰度在中午达到最高，随后迅速消失。RubisCO酶活性和全细胞碳固定在1600时升高，并在接下来的8小时内消失。相比之下，在陀螺拟球藻中，rbcL转录本丰度在1600时最高，并在黑暗期（2000）维持在该水平的66%。全细胞碳固定和RubisCO活性在黑暗期（2000）升高，分别为最大值的77%和81%。在天然浮游植物种群中也观察到了类似的蓝细菌样和色素植物样rbcL转录的日变化模式。这些研究表明，与蓝藻相比，色素植物更适应在一天的晚些时候利用碳固定。
