Effect of the Nitrogen Supply on the Activities of Isoenzymes of NADH-dependent Glutamate Synthase and Glutamine Synthetase in Root Nodules of Phaseolus vulgaris L.

This paper has investigated the regulation of the activitiesof glutamine synthetase (GS) and NADH-dependent glutamate synthase(NADH-GOGAT) of Phaseolus vulgaris in relation to the nitrogensupply. The activity of NADH-GOGAT II, which is the most abundantisoenzyme of glutamate synthase in root nodules of P. vulgaris,was either absent or barely detectable in other organs of thisspecies. Moreover, its activity in roots could not be inducedby ammonium. In nodules NADH-GOGAT II activity was detectedin nodules grown under an atmosphere of 80% argon: 20% oxygenand in nodules formed with a Fix- Rhizobium mutant. However,in these non-fixing nodules the activity of this isoenzyme attainedless than 15% of the activity in fixing nodules and switchingargon/oxygen grown nodules to nitrogen/oxygen led to an increasein this isoenzyme within 24 h. This effect could not be mimickedby the addition of exogenous ammonium. Ammonium addition, however,promoted nodule senescence and also led to a decrease in theactivities of nitrogenase and plant GS. In particular, the nodule-enhancedGS isoenzyme but not the GSß isoenzyme was affectedby these changes and in a manner similar to the changes in NADH-GOGATII. The activity of the NADH-GOGAT I isoenzyme was detectablein other organs of P. vulgaris and in nodules its activity alsoshowed some changes in response to the rate of dinitrogen fixation. Key words: Glutamate synthase, glutamine synthetase, nitrogen fixation, nodule metabolism, Phaseolus vulgaris     

金色蝗属一新种（直翅目：蝗总科）

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作者在整理生物系标本室蝗虫标本时,发现金色蝗属一新种,现报道如下。模式标本保存于东北师范大学生物系动物标本室。 呼盟金色蝗 Chrysacris humengensis新种(图1—3) 雌虫:体中型,较粗壮。头顶短,其长度小于复眼前最宽处的2倍,具中隆线;缺头侧窝;颜面倾斜与头顶形成锐角。颜面隆起明显,在中单眼之下具浅纵沟。触角狭剑状,超     

吉林省异爪蝗属一新种(直翅目:蝗总科)

作者在整理生物系动物标本室蝗虫标本时,发现异爪蝗属一新种,现报道如下。本文长度单位为mm。 左家异爪蝗Euchorthippus zuojianus新种 雄性:体型中等偏大。头顶向前倾斜,侧面观颜面向后倾斜。头侧窝明显,长方形,长为宽的3倍。颜面隆起较狭,两侧缘隆线明显,中央具纵沟。头预前缘近乎直角。头顶