摘要
肿瘤抑制基因p5 3和原癌基因c myc已被证明在动物中高度保守并参与许多PCD过程。这两个基因编码的同源蛋白及其RNA在玉米中的存在已有报道 ,并且其DNA同源序列已利用荧光原位杂交定位在玉米相应的染色体上。利用免疫组织化学方法探测了与人类p5 3和c myc基因同源的玉米基因在玉米颖果发育过程中的时空表达模式。结果发现 ,在授粉后的一定阶段 ,在反足细胞、珠被、未成熟的胚乳、子房壁、导管组织和糊粉层中 ,p5 3同源基因表达强烈 ,c myc同源基因的表达相反 ,在授粉后的这些组织中基本不表达 ,而在授粉前的中央细胞的极核中表达水平较高。TUNEL检测显示 ,在p5 3同源基因呈现高水平表达的地方 ,DNA断裂信号强烈。在动物细胞中 ,p5 3和c myc起相反的调节作用 ,这与其同源基因在玉米中的作用模式相似。由此说明p5 3和c myc同源基因可能在玉米颖果发育PCD过程中起重要作用 ,并进一步推论高等植物PCD和动物细胞凋亡存在一定的保守性机制。
Tumor suppressor gene p53 and proto oncogene c myc have been proved to be highly conserved and participate in many PCD processes in animals.In maize,proteins and RNAs related to p53 and c myc have already been reported and the sequences homologous to these two genes have also been localized onto maize chromosomes by FISH.In this study,using immunohistochemistry we investigated the expression patterns of maize genes homologous to human p53 and c myc during caryopsis development stages in maize.In a giving stage after pollination, p53 homologue showed high levels in the antipodal cells,integument,immature endosperm,ovary wall,tracheary elements,and aleurone layer,while c myc homologue showed low levels in these tissues,only before pollination showed high expression in polar nucleus.The results of TUNEL assay demonstrated that TUNEL positive signals were detected where p53 homologue showed high expression levels.In animal cells, p53 shows reverse function with that of c myc , so does it in maize basically.These results demonstrated that p53 and c myc homologues might play some important roles in PCD during caryopsis development in maize.There may be conserved mechanisms for PCD in animals and in high plants.
基金
国家自然科学基金项目 (编号 :3 0 0 3 0 73 6)资助~~
