Holtzendorff Julia, Marie Dominique, Post Anton F, Partensky Frédéric, Rivlin Assaf, Hess Wolfgang R
Humboldt-University, Institute of Biology/Genetics, Chausseestr. 117, D-10115 Berlin, Germany.
Environ Microbiol. 2002 Nov;4(11):644-53. doi: 10.1046/j.1462-2920.2002.00347.x.
The expression of ftsZ, encoding the initiating protein of the prokaryotic cell division was analysed in natural Prochlorococcus populations in the Gulf of Aqaba, northern Red Sea. During the seasonal Prochlorococcus bloom in September 2000, picoplankton was collected from the deep chlorophyll maximum (DCM) at 2-4 h intervals over 3 consecutive days. Flow cytometric measurements as well as DNA sequence analyses showed that Prochlorococcus was the dominant photosynthetic organism. Cell densities peaked as high as 1.4 x 10(5) cells ml(-1). This DCM population mainly consisted of brightly red fluorescing Prochlorococcus cells, corresponding to low light-adapted 'ecotypes' (sensu Moore et al., 1998, Nature 393: 464-467). Prochlorococcus populations grew in a highly synchronized fashion with DNA replication in the afternoon and cell division during the night. The ftsZ mRNA level reached maximum values within the replication phase between 14.00 and 16.00 hours, and minimum values between 02.00 and 06.00 hours. Thus, the transcriptional regulation of ftsZ could be a major factor triggering the synchronized cell division of Prochlorococcus populations. This is the first application of quantitative reverse transcriptase-coupled real-time polymerase chain reaction (PCR) to natural populations of an environmentally relevant marine organism.
对编码原核细胞分裂起始蛋白的ftsZ在红海北部亚喀巴湾的天然原绿球藻种群中的表达进行了分析。在2000年9月原绿球藻季节性大量繁殖期间，连续3天每隔2 - 4小时从深层叶绿素最大值（DCM）处采集微微型浮游生物。流式细胞仪测量以及DNA序列分析表明，原绿球藻是主要的光合生物。细胞密度峰值高达1.4×10⁵个细胞/毫升。这个DCM种群主要由发出鲜红色荧光的原绿球藻细胞组成，对应于适应弱光的“生态型”（参照Moore等人，1998年，《自然》393：464 - 467）。原绿球藻种群以高度同步的方式生长，DNA复制在下午进行，细胞分裂在夜间进行。ftsZ mRNA水平在14:00至16:00的复制阶段达到最大值，在02:00至06:00之间达到最小值。因此，ftsZ的转录调控可能是触发原绿球藻种群同步细胞分裂的主要因素。这是定量逆转录酶偶联实时聚合酶链反应（PCR）首次应用于与环境相关的海洋生物的天然种群。
