水稻CaM和Ca^(2+)-ATPase基因的原位杂交物理定位

PHYSICAL LOCALIZATION OF GENES FOR CaM AND Ca2+ATPase IN RICE BY IN SITU HYBRIDIZATION

ＣａＭ为重要的调控蛋白，Ｃａ２＋ＡＴＰａｓｅ则是重要的ＣａＭ结合蛋白，它和ＣａＭ一起构成信号传递通路中的重要组成部分，是功能上密切相关的两个基因。以生物素标记这两个基因的ｃＤＮＡ为探针，用原位杂交技术将它们定位到了水稻（ＯｒｙｚａｓａｔｉｖａＬ．）染色体上，检出率为６．１８％。ＣａＭ和Ｃａ２＋ＡＴＰａｓｅ基因被分别定位于第５染色体长臂的末端和第５染色体短臂紧靠着丝粒处。所检出染色体的臂比及标准差分别为１．７９±０．０６和１．９１±０．０８。二者在遗传图中相距较近，而在基因组物理图中位于同一染色体上不同的染色体臂上，说明基因的遗传图和物理图之间存在差异。并对短片段，低拷贝或单基因的技术进行了讨论。

CaM and Ca2+ATPase genes are important components of signal transduction chains which affect the regulation of gene expression and development in plants. These two genes are functionally closely related. The rice (Oryza sativa L.) cDNA probes C419 and SSU304 for these two genes, which are small singlecopy ones and 0.8 and 0.3 kb in size respectively, were first physically mapped on rice chromosomes by biotinlabeled in situ hybridization. Both probes were detected on chromosome 5. The detection rate was 6.18%, and the average chromosome arm ratios and standard deviations of detected chromosomes for probes C419 and SSU304 were 1.79±0.06 and 1.91±0.08 respectively. Probe C419 for CaM gene was located at the end of the long arm, and probe SSU304 for Ca2+ATPase gene — on the short arm near the centromere. As it was reported before, they were closely linked in the high density genetic map. This demonstrated that there was a large discrepancy between the results of genetic and physical mapping of genes, and it indicated that the region between the functionally related genes could be the cold spot. What relationship there is between the region and gene expression is to be studied further. The nonradioactive in situ hybridization technique about the physical mapping of low/single copy, short DNA fragments is also discussed.