烟草愈伤组织继代培养期间呼吸途径与活性氧水平动态变化

继代培养期间的烟草愈伤组织总呼吸速率分别在第11天和第19天出现两次跃升,同时抗氰呼吸的发生与运行逐渐加强,在两呼吸高峰之间达到极大值,随后则逐渐下降,但愈伤组织的电子传递仍以细胞色素途径为主．通过对愈伤组织衰老过程中活性氧代谢变化分析,发现抗氰呼吸发生与H     

The Cyanide-resistant Respiration in Callus of Nicotiana rustica cv. Gansu Yellow Flower Under Low Temperature

The increasement of the operation (ρValt) and the capacity of the alternative pathway (Valt) in tobacco (Nicotiana rustica L. cv. Gansu Yellow Flower) callus that treated by low temperature (4 ℃) were observed. The two electron transport pathways were changed alternatively, the cyanide-resistant respiration was the main respiratory pathway from the 2nd day to the 5th day, while the cytochrome pathway was the main pathway consistently in control callus. Cycloheximide and chloramphenicol treatment which inhibited protein synthesis resulted in dramatic and partly inhibition of Valt induced by low temperature respectively. This further proved above result that low temperature induced Valt. The same result was found when two inhibitors were used together. The analysis of heat production of callus indicated that the operation of the alternative pathway could be regulated to improve the micro-environmental temperature of tobacco callus to adapt to low temperature. The possible participation of the alternative pathway in the response to low temperature and its physiological roles were discussed.     

Effects of KCN and NaN3 Pretreatment on the Cyanide-Resistant Respiration in Tobacco Callus

The effects of KCN (0.5mmol/L) and NaN3 (0.01 mmol/L) pretreatment on the operation of the alternative pathway in subcultured tobacco (Nicotiana rustica L. cv. Gansu yellow flower) callus were analyzed. After treatment with KCN and NaN3 for 12 h, the total respiration rate (Vt) decreased by 12% and 17%, whereas oxygen consuption by the cytochrome pathway decreased by 22% and 28% respectively. The capacity of the alternative pathway (Valt) remained constant, while the activity of the alternative pathway (ρ· Valt ) inreased slightly. This changing pattern led to a declined contribution of the cytochrome pathway to the total respiration rate and an increased activity of the alternative pathway. Treatment with KCN for 24 h brought about a slight rise of oxygen consumption by the cytochrome pathway as compared with that in callus treated for 12 h, but the oxygen consumption was still lower than that in the untreated callus. Treatment with NaN3 for 24 h resulted in a profound decrease of the cytochrome pathway operation and a continuing increase of the alternative pathway operation. These data indicated that the enhanced operation of the alternative pathway played a compensatory role to the total respiration when the cytochrome pathway was partially inhibited in tobacco callus.     

Relationship Between Endogenous Ethylene and the Development and Operation of the Alternative Respiratory Pathway in Aged Potato Tuber Slices

The relationship between endogenous ethylene and the development and the operation of the alternative respiration pathway in aged potato (Solanum tuberosum L. ) tuber slices were investigated. During the 24 h aging period under 30 ℃, along with the great increase of the total respiratory rate (Vt) of the slices, the alternative pathway capacity (Valt) developed continuously, and the Valt/Vt values kept increasing as well. Both the alternative pathway activity (ρValt) and its contribution to Vt(ρValt/Vt) also increased gradually before 12 h of aging, but kept constant from 12 h to 24 h. The time course of the endogenous ethylene production of the aged slices was similar to the changing trends of Valt and Valt/Vt, but different from those of ρValt and ρValt/Vt values. ACC and Cu2 + treatment which stimulated ethylene production of the aged slices enhanced their Valt and Valt/ Vt values, Co2 + and Ag+ treatment resulted in a decreased effect. However, all the above treat ments of ethylene-related agents could not alter the continuously decreasing trend of the ρ value of the alternative pathway of the aged slices. And their effects on ρValt and ρValt/Vt values were only observed before 12 h of aging. These results suggested that the endogenous ethylene was essential to the development of the capacity of alternative pathway, but could only slightly influence the operation of the activity of the alternative pathway in aged potato tuber slices.     

盐逆境下转基因耐盐小麦与其受体呼吸途径的动态变化

以转基因耐盐品种８９１２２和其受体陇春１３号两种小麦为实验材料,研究科幼苗在不同盐浓度胁迫下呼吸途径动态变化。结果表明,８９１２２出现盐呼吸明显迟于其受体;两听Ｖａｌｔ与ρＶａｌｔ变化并不同步,且Ｖａｌｔ均受高盐浓度的抑制,但低盐浓度能诱导其受体的Ｖａｌｔ;两品种的ρＶａｌｔ与ρ′Ｖｃｙｔ彼此协同调节适应盐境,且ρ′Ｖｃｙｔ仍是盐胁迫过程中线粒体电子传递的主要途径。同时讨论了盐逆境下抗氰呼吸的一些     

外源~1O_2 和·OH及其清除剂对烟草愈伤组织交替途径发生与运行的影响(英文)

外源1 O2 和·OH处理继代培养 1 4d的烟草愈伤组织 2 4h后 ,愈伤组织内的交替途径的实际运行显著上升 ,但对交替途径容量影响不大 ;而经·OH处理后的愈伤组织交替途径容量和实际运行均明显地受到抑制 ,但交替途径的实际运行对·OH更加敏感。活性氧产生系统中加入相关清除剂进行实验 ,得到与此相对应的结果 :1 O2 的清除剂His处理能明显地降低或抑制1 O2 所增加的交替途径实际运行量 ,但对交替途径容量则几乎均无影响 ,而用·OH的清除剂DMSO和MAN分别处理愈伤组织后 ,DMSO和MAN均能解除·OH对交替途径容量和实际运行的抑制。这些结果表明 ,1 O2 诱导烟草愈伤组织交替途径的实际运行 ,但对其容量的作用不大 ,而·OH则明显地抑制交替途径容量和实际运行。推测1 O2 和·OH对抗氰途径的影响可能是通过对AOX活性的调节     

H2O2和水杨酸对陈化马铃薯切片交替呼吸途径影响的比较

外源5.0 mmol/L H2O2和0.1 mmol/L 水杨酸(salicylic acid, SA)处理均可明显提高陈化24 h的马铃薯切片的交替呼吸途径容量(Valt)及其与总呼吸的比值(Valt/Vt).应用交替氧化酶的单克隆抗体进行Western杂交的结果表明,H2O2和SA处理均可明显提高陈化马铃薯切片中交替氧化酶的表达水平.用氧同位素分辨法研究,结果表明:H2O2处理对陈化马铃薯切片中交替呼吸途径的实际运行没有影响,而SA处理对交替呼吸途径的实际运行具有明显的促进作用.上述结果表明,H2O2和SA对植物组织交替呼吸途径的影响存在差异,二者均可促进交替氧化酶的表达从而诱导交替呼吸途径容量的发生,但H2O2不影响其实际运行,而SA还可同时诱导其实际运行.     

不同低温胁迫对烟草愈伤组织抗氰交替途径诱导和交替氧化酶表达影响的比较

比较了不同低温(14℃和4℃)胁迫对烟草(Nicotiana rusticaL．)愈伤组织抗氰交替途径诱导和交替氧化酶表达的影响。结果显示,不同低温胁迫处理能显著诱导烟草愈伤组织交替途径容量和实际运行的增加,且都呈现出基本相同的变化模式：在胁迫的初期(1—3d)持续增加,在3d时达到最高,而后下降到一个相对恒定的水平。但交替途径容量增加的幅度与温度下降的程度密切相关,而交替途径实际运行量的诱导程度在不同低温胁迫下的差异却很小。表明交替途径容量和实际运行对低温胁迫的响应是不同的。免疫印迹分析结果表明：低温胁迫明显诱导了交替氧化酶总蛋白的增加,且其随低温胁迫进程的变化与交替途径容量的变化基本一致;而对交替氧化酶单体与二聚体在低温胁迫下的含量变化检测结果则显示,烟草愈伤组织中交替氧化酶主要以二聚体形式存在,且这一存在形式并不随低温胁迫程度的加深而发生改变。两种形式的交替氧化酶蛋白含量都能被低温胁迫诱导增加,但其单体水平在两种不同的低温胁迫下并无明显差别,而4℃低温胁迫诱导的二聚体交替氧化酶蛋白含量明显高于14℃。表明不同程度低温对抗氰交替途径发生的不同影响主要是由于对交替氧化酶蛋白二聚体形式的不同诱导程度所致;而高活性的交替氧化酶单体形式则不因低温胁迫程度的加重而被明显诱导升高,使得抗氰交替途径的运行程度在两种不同的低温胁迫处理条件下无显著差异。     

The operation of the alternative electron-leak pathways mediated by cytochrome c in mitochondria

Low (1 x 10(-9)M) concentrations of cytochrome c inhibit H2O2 production in cytochrome c-depleted mitochondria, purified succinate-cytochrome c reductase (SCR) and antimycin A inhibited cytochrome c-depleted HMP. At higher concentration (2 x 10(-6)M), cytochrome c eliminates pre-existed H2O2 if feeding electrons to it by succinate. Cytochrome c also decreases the OH* produced by succinate-cytochrome c reductase oxidizing succinate. We conclude that the alternative electron-leak pathway mediated by cytochrome c operates very well. In the presence of antimycin A, ferrocytochrome c can suppress the generation of H2O2 in SCR system, but ferricytochrome c cannot. Similar results are obtained on the elimination of pre-existed H2O2 by cytochrome c. For hydroxyl radical, antimycin A abolishes the suppression caused by both ferrocytochrome c and ferricytochrome c. These results indicate that the reductive state of cytochrome c caused by electron-flow is necessary and sufficient for the operation of cytochrome c-mediated electron-leakage pathway.     

A Comparative Study of CN-Resistant Respiration in Different Cultures of Tobacco Callus

The callus of Nicotiana rustica cv Gansu yellow flower and N. tabacum cv willow leaf were cultured on ordinary subculture medium (M-1) and on regeneration medium (M-2), respectively. No differentiation was observed in Gansu yellow flower tobacco callus cultures grown on both M-1 and M-2 medium. The respiration of both cultures was partially resistant to cyanide and markedly inhibited by m-chlorobenzhydroxamic acid. The relative contributions of alternative and cytochrome pathway were 31% and 47% of the total respiration, respectively, in M-1 callus cultures. The relative O₂ uptake of the two pathways was not changed significantly in M-2 callus cultures. In subcultured M-1 callus cultures of Willow leaf tobacco, the respiration mediated via alternative pathway was about 29 to 38% of the total respiration, and the cytochrome pathway still was the major respiratory pathway. In M-2 callus cultures in which differentiation occurred, the relative contribution of alternative pathway increased to 41 to 47% of the total respiration, and the cytochrome pathway decreased considerably. These results suggested that the change of respiratory electron transport pathway was probably related to the differentiation of tobacco callus cultures.