植物の温度検知機構の分子生物学的解析

1.目的：植物受到低温胁迫时，会在膜脂脂肪酸中引入双键，以补偿低温引起的膜分子运动的降低。这一现象表明，植物可以检测到温度的变化，并将这种信号转导到去饱和酶基因的表达。本研究的目的是研究温度诱导蓝藻脱饱和酶表达的调控方式。结果：(1)以集胞菌PCC6803的DESA为探针，从集胞菌PCC6714和集胞菌PCC7002中克隆了DELTA12位的植物类型去饱和酶基因(DESA)。将这些DesA基因转化不能DELTA12去饱和的聚球藻PCC7914后，该菌株获得了在DELTA12位引入双键的能力。对集胞藻PCC6803中DesA基因表达的Northern印迹分析表明，随着温度的降低，DesA基因的转录显著增强。(3)将pBSDELTAAv载体构建的启动子检测盒导入集胞藻PCC6803基因组中。在产生的一些突变体中，有些对温度变化有反应，我们现在正在寻找对温度负责的启动子。

1. Purpose: When plants are exposed to low-temperature, they introduce double bonds into fatty acids of membrane lipids, which compensates the decrease in molecular motion of membranes caused by low temperature. This phenomenon suggests that the plants can detect the change in temperature and transduce this signal to the expression of desaturase genes. The purpose of this research is to study the mode of temperature-induced regulation of desaturase expression in cyanobacteria.2. Results:(1) Genes (desA) for plant-type desaturases at the DELTA12 position were cloned from Synechocystis PCC6714 and Synechococcus PCC7002 with a probe derived from desA of Synechocystis PCC6803. When Synechococcus PCC7914, which is incapable of the DELTA12 desaturation, was transformed with these desA genes, this strain acquired the ability to introduce the double bond at the DELTA12 position. These observations confirm that the cloned genes were all desA.(2) The northern blot analysis of desA gene expression in Synechocystis PCC6803 demonstrated that the transcription of desA gene was markedly enhanced upon decrease in temperature.(3) A Promoter-detecting cassette constructed from the plasmid pBSDELTAAv was introduced into the genome of Synechocystis PCC6803. In a number of mutants produced some responded to temperature changes We are now identifying the temperature-responsible promoters.