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151.
几种木本植物的N2O释放与某些生理活动的关系 总被引:20,自引:4,他引:16
使用带有开放气路的气体交换测定系统,同步测定了几种针、阔叶树种的光合作用、呼吸作用及气孔导度.结果表明,低光下树木针叶或叶片释放N2O的速率与光合速率无显著相关.伴随根、茎、叶的呼吸,检测到有N2O吸收现象,其通量与温度及呼吸强度呈正相关.气孔导度明显影响N2O的通量,表明气孔可能是木本植物释放N2O的主要途径. 相似文献
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153.
武汉东湖水生植被及其恢复途径探讨 总被引:4,自引:0,他引:4
1992~1993年对武汉东湖三个主要湖区(郭郑湖、汤林湖和牛巢湖)水生植被的调查表明,该湖区共有水生植物32种,优势种为大茨藻、狐尾藻、苦草和菱。金鱼藻呈不断扩大的趋势。植被类型可分为11个群丛,植被面积约为0.65km ̄2,总生物量为1236.39t(湿重),植被带状分布仅见于汤林湖北部和其他部分湖汊。汤林湖和牛巢湖水生植被正处于自然恢复演替阶段。 相似文献
154.
多异瓢虫生物学的研究 总被引:3,自引:0,他引:3
多异瓢虫在山东省德州地区一年发生4代,部分个体5代,以成虫在杂草丛内、残枝落叶及土块下越冬。在自然变温下,卵、幼虫、预蛹、蛹、成虫产卵前期和全世代的发育始点和有效积温分别为18.8±0.52℃和15.0日度、16.97±0.03℃和73.3日度、15.97±0.01℃和10.23日度、15.47±0.05℃和23.05日度、17.6±0.04℃和34.1日度、18.2±0.10℃和170.3日度。据Holing圆盘方程测定,1─4龄幼虫和产卵前期成虫日最大捕食棉蚜量依次力6.7头、36.4头、77.5头、81.3头和68.0头。 相似文献
155.
通过DNA体外重组技术,以pET-3b为表达载体,构建了重组表达质粒pET-6R(B)和PET-6R(B)4,分别编码28kD的hIL-6R配基结合区片段及其53kD的二联体蛋白,并为酶切分析和DNA序列分析所证实。SDS-PAGE分析表明,含有重组表达质粒的菌株可分别表达出28kD的蛋白rIL6R-28和53kD的rIL6R-53。重组蛋白分别占菌体总蛋白的45%和29%左右。重组蛋白主要以包涵体形式存在,Western印迹表明重组蛋白具有IL-6R的抗原性。 相似文献
156.
Enrique Galindo Guadalupe Salcedo Ma. Eugenia Ramírez 《Applied microbiology and biotechnology》1994,40(5):634-637
Xanthomonas campestris NRRL B-1459 and a variant E2, when preserved on agar slopes (transferred monthly) over 11 months did not deteriorate in their ability to produce xanthan in quantity and quality, as determined by culture in 500-ml baffled flasks. Variations between 8 and 14% (with respect to the average) in the final xanthan concentration were observed for the E2 and B-1459 strains, respectively. A wide range of final viscosities was obtained; these were consistent with the changes in gum concentration. Differences were more likely associated with differences in fermentation kinetics rather than being inherent to the strains. The rheological quality of both polysacharides was relatively constant throughout the time of culture maintenance. Preservation of these bacteria on agar slopes was an adequate method, in contrast to previous reports. In the period studied, strain E2 produced higher gum titres and slightly lower gum quality compared to strain B-1459.
Correspondence to: E. Galindo 相似文献
157.
158.
Ma Victoria Amores Paloma Hortelano Leticia García-Salguero José A. Lupiáñez 《Molecular and cellular biochemistry》1994,137(2):117-125
We have studied the effects of the diuretics mersalyl, furosemide and ethacrynic acid on renal gluconeogenesis in isolated rat-kidney tubules and on the activities of the most important gluconeogenic and glycolytic enzymes in both fed and fasted rats. Mersalyl (15 mg.kg–1 animal weight) significantly decreased the rate of gluconeogenesis in well-fed rats (68%) as well as in 24 and 48-h fasted ones (33 and 37% respectively). This inhibition occurred when lactate, pyruvate, glycerol or fructose were used as substrates. Ethacrynic acid at a dose of 50 mg.kg–1 animal weight provoked a transient inhibition of renal glucose production by almost 20% but only in fed rats with lactate as substrate, whereas the same dose of furosemide did not affect this metabolic pathway.Parallel to these changes, mersalyl caused a significant inhibition in the maximum activity of the most important gluconeogenic enzymes, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase, in both fed and fasted rats. Neither ethacrynic acid nor furosemide produced any variations in the activities of these enzymes. The activity of the glycolytic enzymes phosphofructokinase and pyruvate kinase was not modified by these diuretics. Nevertheless, the activity of the thiol-enzyme glyceraldehyde 3-phosphate dehydrogenase was severely inhibited by mersalyl and to a lesser extent by the other diuretics. This inhibition was higher in fasted than fed rats. Hence, we conclude that the inhibitory effect of mersalyl on renal gluconeogenesis is due, at least partly, to a decrease in the flux through the gluconeogenic enzymes. Blood glucose was not modified after diuretic treatment in fed animals whereas mersalyl decreased the levels of blood glucose in 24-h fasted rats. Thein vivo effects of diuretics on gluconeogenesis correlate well with the previously observedin vitro effects, although ethacrynic acid was less potent as an inhibitorin vivo, probably because of its rapid clearance.Abbreviations EDTA
ethylenediaminetetraacetic acid
- EGTA
ethyleneglycolbis (-aminoethylether) N,N,N,N-tetraacetic acid
- DTT
dithiothreitol
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- TRIS
2-amino-2-hydroxymethyl-1,3-propanediol
Publication No. 166 from Drogas, Tóxicos Ambientales y Metabolismo Celular Research Group, Department of Biochemistry and Molecular Biology, University of Granada, Granada, Spain 相似文献
159.
160.
Multivalent cations condense DNA in vitro, but it had been thought that a valence of at least + 3 was required in aqueous solution. We have found that Mn2+ can produce toroidal condensates of supercoiled plasmid DNA, but not of linearized plasmid. Mg2+ does not cause condensation, and neither MgCl2 nor NaCl can negate the effect of MnCl2, indicating that the condensation mechanism with Mn is not primarily electrostatic. Supercoiled MnDNA is more extensively digested than the linear form by S1 nuclease. Supercoiling appears to cooperate with Mn2+ in stabilizing helix distortions and also provides a "pressure" that enhances lateral association. 相似文献