【作者】 张吉；

【导师】 张楚富；

【作者基本信息】 武汉大学 ， 生物化学与分子生物学， 2004， 硕士

【摘要】 测定了不同培养条件下,丝瓜种子萌发及子叶发育时期子叶中谷氨酰胺合成酶(GS)、依赖于NAD(H)的谷氨酸脱氢酶(GDH)和依赖于NADP的异柠檬酸脱氢酶(ICDH)活性的变化,以及可溶性蛋白、总可溶性糖和其他参数的变化。结果表明在不同条件下,总的GS活性在丝瓜种子的萌发以及子叶发育过程中都是呈现先升后降的趋势,在子叶绿化后有着明显的活性上升。Native-PAGE结合活性染色以及免疫印迹分析,显示在光照下以及暗处培养的子叶都呈现两条同工酶活性带,且都能别水稻GSrb抗体识别。两条酶带的出现表现出固定的时间顺序,光和外源氮对GS同工酶活性都有明显的促进作用。GDH的活性变化则与GS存在差异,在子叶绿化后开始下降,GDH可能并不直接参与种子萌发后的氨的再同化过程。NADP-ICDH的活性与GDH类似,都在种子萌发后下降;在光照下,伴随着子叶的绿化,NADP-ICDH的活性迅速降低,直至下降到检测不到的水平;在暗处,NADP-ICDH的活性则一直维持较低活力。 上述结果提示在丝瓜种子萌发以及子叶发育过程中,存在两种受外界因素诱导的GS同工酶,GS在此过程中扮演着氨同化的主要角色;而在此过程中,NADP-ICDH也许并非以与GS相对应的方式为氮素的同化提供碳架以及参与氮素转移,NAD(H)-GDH以及NADP-ICDH在碳氮代谢中的真实生理作用仍然需要进一步证实。更多还原

【Abstract】 The activities of glutamine synthetase (GS) , NAD (H) -dependent glutamate dehydrogenase (NAD (H) -GDH), NADP-dependent isocitrate dehydrogenases (NADP-ICDH) ,the level of tatol soluble protein and soluble sugar were determined during germination and cotyledon development in Luffa cylindrical. The total GS activities of cotyledons increased when cotyledons turned green. Native-PAGE analysis, together with activity staining and western blot assays, showed there were two GS isoforms in both green and etiolated cotyledons.The two isoforms expressed individually and could both be recognized by antibodies against rice GSrb. And both isoforms could be induced by light or nitrogen. The activities of NAD(H)-GDH reached the max at the end of germination and kept decreasing after cotyledon turned green. NADP-ICDH activities changed a little similar like GDH’s, increasing during germination and decreasing later. NADP-ICDH activities could hardly be detected in green cotyledons, but still remained in etiolated ones. The results declared that GSwas the real key enzyme in ammonium assimilation during germination and cotyledon development, besides, GDH might play an alternative role in C/N flows. NADP-ICDH showed a similar pattern as GS during germination, but its dramatic decline in green cotyledon implies its other functions in vivo.更多还原