抗坏血酸对沙打旺原生质体分离和培养中膜损伤及相关酶活性的 …

抗坏血酸（ＡＳＡ）能减轻沙打旺原生质体的褐化,改善原生质体的培养状况,ＡＳＡ的作用可能与它增强原生质体抗过氧化能力有关。酶解处理诱导原生质体超氧化物歧化酶（ＳＯＤ）和抗坏血酸过氧化物酶（ＡＰＸ）活性升高,但培养过程使ＡＰＸ活性明显下降,原生质体清除过氧化物能力减弱,膜脂过氧化产物丙二醛（ＭＤＡ）积累增加,膜发生损伤。向酶溶液和培养基中添加ＡＳＡ可显著提高ＳＯＤ尤其是ＡＰＸ活性,减轻膜脂过氧化,增强     

三唑酮对黄瓜子叶抗氧化酶活力的影响

黄瓜子叶衰老过程中超氧物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）和抗坏血酸－过氧化物酶（ＡＳＡ－ＰＯＤ）活性降低,而过氧化物酶（ＰＯＤ）活性升高。２０ｍｇ／Ｌ三唑酮右明显提高ＳＯＤ,ＡＳＡ－ＰＯＤ,ＣＡＴ活性,抑制ＰＯＤ活性升高。膜脂过氧化产物丙二醛（ＭＤＡ）含量在叶片衰老过程中提高,三唑酮可降低ＭＤＡ含量。表明三唑酮减轻脂氧化程度,延缓了叶片的衰老。     

小麦原生质体分离过程中生理状态的变化

酶解处理使小麦对肉原生质体膜流动性降低,膜脂过氧化产物丙二醛（ＭＤＡ）积累,说明脱璧过程对细胞有伤害作用,损伤位点可能发生在膜上。胚性愈伤组织的具有分裂能力的原生质体,不表现上述变化。酶解脱壁还使超氧化物歧化酶（ＳＯＤ）和过氧化氢酶（ＣＡＴ）活性上升;过氧化物酶（ＰＯＸ）在叶肉原生质体中活性下降,在胚性愈伤组织来源的原生质体中活性上升。以上结果表明：在原生质体分离过程中,细胞的生理特性发生了变化;膜损伤的发生可能与原生质体能否进入正常分裂状态有关。     

NaCl胁迫对螺旋藻生长及抗氧化酶活性的影响

在０１％～５．０％ＮａＣｌ浓度范围的培养基中培养极大螺旋藻（Ｓｐｉｒｕｌｉｎａｍａｘｉｍａ）,发现ＮａＣｌ浓度高于２．０％时螺旋藻生长受到明显抑制。培养７天后测定超氧化物歧化酶（ＳＯＤ）、抗坏血酸过氧化物酶（ＡＳＡＰＯＤ）、过氧化氢酶（ＣＡＴ）活性和丙二醛（ＭＤＡ）含量。结果表明：在盐胁迫下,ＳＯＤ酶活性升高;抗坏血酸过氧化物酶和过氧化氢酶活性在低盐胁迫下活性升高,高盐胁迫下抗坏血酸过氧化物酶活性迅速降低,过氧化物酶则完全失活;ＭＤＡ含量先随盐胁迫程度增加而降低,后随盐胁迫的进一步增强恢复至对照水平。     

作物细胞耐旱保护酶系统对外磁场的反应

作物细胞的耐旱保护酶由过氧化物酶（ＰＯＤ） 、过氧化氢酶（ＣＡＴ） 和超氧化物歧化酶（ＳＯＤ） 组成。对小麦种子施加０．１Ｔ 的磁场处理使其萌发时细胞中ＰＯＤ 活性提高,幼苗根系和叶片细胞中的ＰＯＤ 活性也发生了变化,叶片的ＰＯＤ 同工酶谱中多出了两个酶带。使用蛋白质合成抑制剂和转录抑制剂发现,ＰＯＤ 活性提高的原因是磁场处理促进了ＰＯＤ 合成的翻译过程。干旱胁迫下,经磁场处理的幼苗叶片细胞中的ＰＯＤ、ＣＡＴ 和ＳＯＤ 活性均比对照高,膜脂过氧化产物丙二醛（ ＭＤＡ） 含量比对照低,表明保护酶系统的功能有所增强。     

小麦胞质不育系花药中脂氧合酶及抗坏血酸过氧化物酶活性的…

在花粉单核期和二核期,Ｋ型不育系花药的脂氧合酶（ＬＯＸ）活性低于而Ｔ型不育系则高于保持系,两者的抗坏血酸过氧化物酶（ＡｓＡ－ＰＯＤ）活性均高于保持系。花粉三核期两种类型不育系的ＬＯＸ活性均明显于高于而ＡｓＡ－ＰＯＤ活性则明显低于保持系。不育系花药的丙二醛（ＭＤＡ）含量在各发育时期均高于保持系,三核期尤为明显。     

三唑酮对绿豆幼苗叶片衰老的延缓作用

三唑酮处理可提高离体绿豆（ＰｈａｓｅｏｌｕｓｒａｄｉａｔｕｓＬ．）幼苗叶片叶绿素和蛋白质含量。叶片衰老过程中超氧物歧化酶（ＳＯＤ）、过氧化物酶（ＰＯＤ）、过氧化氢酶（ＣＡＴ）和抗坏血酸过氧化物酶（ＡｓＡＰＯＤ）活性及抗坏血酸（ＡｓＡ）和还原型谷胱甘肽（ＧＳＨ）含量降低。２０ｍｇ／Ｌ三唑酮可提高ＰＯＤ、ＡｓＡＰＯＤ活性和ＡｓＡ、ＧＳＨ含量,对ＳＯＤ、ＣＡＴ活性无影响。丙二醛（ＭＤＡ）含量在叶片衰老过程中提高,并与ＰＯＤ、ＡｓＡＰＯＤ活性和ＡｓＡ、ＧＳＨ含量呈显著负相关,三唑酮可降低ＭＤＡ含量。表明三唑酮有提高植物对膜脂过氧化作用的保护能力,延缓叶片的衰老作用。     

低温胁迫下红松幼苗活性氧的产生及保护酶的变化

在不同低温胁迫时间下,对红松（Ｐｉｎｕｓ ｋｏｒａｉｅｎｓｉｓ Ｓｉｅｂ．ｅｔ．Ｚｕｃｃ）幼苗针叶中Ｈ２Ｏ２、Ｏ＾－．２、膜脂过氧化产物丙二醛（ＭＤＡ）、组织自动化氧化速率及保护酶超氧化物歧化酶（ＳＯＤ）、过氧化物酶（ＰＯＤ）、过氧化氢酶（ＣＡＴ）和抗坏血酸过氧化物酶（ＡＳＰ）的动态变化过程进行了测定。结果表明,随着低温胁迫时间的延长,Ｏ＾－．２产生速率和Ｈ２Ｏ２含量先上升后下降;ＭＤＡ的含量呈波     

杂交稻抗感白叶枯病与活性氧伤害及防御酶系统的关系

以对白叶枯病抗感不同的三个杂交稻为材料,在三叶期接种白叶枯病强毒菌株７６—２５,结果表明,杂交稻接种白叶枯病菌７２ｈ后,苯丙氨酸解氨酶（ＰＡＬ）活性和过氧化物酶（ＰＯＸ）活性升高,超氧化物歧化酶（ＳＯＤ）活性下降,膜脂过氧化产物丙二醛（ＭＤＡ）含量增加,且抗病组合的变化幅度大于感病组合,说明杂交稻抗白叶枯病与活性氧伤害及保护酶系的活性相关。     

镍对离体玉米叶片衰老的调节作用

本文研究了镍对离体玉米叶片衰老的调节作用。研究结果表明,玉米叶片在衰老过程中,超氧化物歧化酶（ＳＯＤ）、过氧化物酶（ＰＯＤ）过氧化氢酶（ＣＡＴ）、抗坏血酸过氧化物酶（ＡsＳ－ＰＯＤ）活性和抗坏血酸（ＡsA)含量显著降低,超氧阴离子自由基（Ｏ^-2)产生率显著增加,脂质过氧化作用加剧,丙二醛（ＭＤＡ）含量升高,细胞质膜透性增大。而１０^-2、１０^-3mol.L^-1Ni^2 处理能增强上述保护酶活性和抗氧化剂ＡsA的含量从而能减轻细胞膜脂过氧化使用。２０^-3、１０^-2mol.L^-1Ni^2 处理能显著延缓蛋白质和叶绿素 降解。因此镍能延缓离体玉米叶片的衰老,尤其是以１０^-2mol.L^-1Ni^2 对衰老的延缓作用更大。动态测定结果表明,１０^-2mol.L^-1Ni^2 处理能使衰老滞后２－天。     

Structure and function of S-adenosylhomocysteine hydrolase

In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine (AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations. These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate (NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases, with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the catalytic domain occurs upon inhibitor/substrate binding.     

Land,livestock, and livelihoods: Changing dynamics of gender,caste, and ethnicity in a Nepalese Village

Over the past 10 years, Ghusel VDC, Lalitpur District has moved from primarily subsistence agriculture into the wider cash economy aided by the Small Farmers' Development Program (SFDP), which provides credit to farmers mainly for the purchase of buffalo for milk production, and by the National Dairy Corporation, which supports local dairy cooperatives. Analysis reveals that buffalo-keeping and milk sales are increasing the well-being of many households, while at the same time creating new inequalities in gender roles and responsibilities, greater inequities between Brahmin and Tamang residents in Ghusel, and placing pressures on the ecosystem for increased supplies of fodder and fuelwood. Evidence suggests that there is critical, need for attention to the social, and particularly gender-based, implications of maintaining livestock for milk sales and to the ecological underpinnings of this livelihood system.     

Tuning of electronic properties of one-dimensional cyano-bridged Cu-Ni, Cu-Pd, and Cu-Pt bimetallic assemblies by stereochemistry of ligands

Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)₂][Pd(CN)₄] · 2H₂O (1), [Cu(trans-chxn)₂][M(CN)₄] · 2H₂O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)₂][M(CN)₄] · 2H₂O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p_1/2 and 2p_3/2 peaks of XPS and broad d-d bands around 18 000 cm⁻¹ of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.     

Influence of Fluoride on Rat Kidney Antioxidant System: Effects of Methionine and Vitamin E

The aim of the study has been to determine and compare the influence upon the kidney antioxidative system, exercised by administration of vitamin E, and vitamin E in combination with methionine, under conditions of oxidative stress induced by sodium fluoride. The experiment was carried out on Wistar FL rats (adult males) that, for 35 days, were administered water, NaF, NaF with vitamin E, or vitamin E with methionine (doses: 10 mg NaF/kg of body mass/24 h, 3 mg vitamin E per 10 μl per rat for 24 h, 2 mg methionine per rat for 24 h). The influence of administered sodium fluoride and antioxidants upon the antioxidative system in kidney was examined by analyzing the concentration of malondialdehyde (MDA) and the activity of the most important antioxidative enzymes (SOD, total and both its isoenzymes, GPX, GST, GR, and CAT). The studies carried out confirmed the disadvantageous effect of the administered dose of NaF upon the antixodiative system in rats (increase in the concentration MDA, decrease activity of all antioxidative enzymes). The administration of vitamin E increased the activity of studied enzymes with the exception of glutathione reductase GR; it also reduced the procesess of lipid peroxidation. It has been found that combined doses of vitamin E and methionine were most effective in inhibiting lipid peroxidation processes. The results confirmed the antioxidative properties of methionine.     

Reorientation of Microfibrils and Microtubules at the Outer Epidermal Wall of Maize Coleoptiles During Auxin-Mediated Growth

Auxin-mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.     

眶额叶微量注射谷氨酸和γ-氨基丁酸对胃运动的影响及其机制探讨

目的:研究眶额叶(OFC)的谷氨酸(Glu)和γ-氨基丁酸(GABA)含量变化对胃运动的影响及其调节神经机制。方法:实验采用了大鼠眶额叶微量注射给药,结合核团损毁的方法,以记录胃内压,统计胃收缩幅度作为胃运动变化的指标。结果:①OFC注射Glu可显著降低胃收缩幅度,损毁杏仁核后可反转该效应,胃收缩幅度显著增强;损毁蓝斑核后,Glu的作用无显著性变化。②OFC注射GABA可显著增强胃的收缩幅度,损毁蓝斑核后消除该效应;损毁杏仁核后,胃收缩幅度进一步增强。结论:外源性增加OFC区Glu含量导致的抑胃效应可能是通过增强了杏仁核的经常性抑胃作用而引起的;而增加OFC区GABA的含量引起的胃运动增强与蓝斑核密切相关。     

邻苯二甲酸二丁酯对翡翠贻贝抗氧化酶及脂质过氧化水平的影响

实验室条件下,研究了不同浓度邻苯二甲酸二丁酯(DBP)长期胁迫(15 d)对翡翠贻贝内脏团和外套膜抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT)及脂质过氧化(LPO)水平(以MDA含量表示)的影响,以及受胁迫翡翠贻贝在清洁海水中恢复阶段上述生化指标的变化特征.结果表明:胁迫阶段,0.5和2.5 mg.L-1DBP下翡翠贻贝内脏团SOD活性表现为先抑制后逐渐恢复,12.5和62.5 mg.L-1下则持续受到显著抑制;不同浓度组CAT活性均明显被抑制.LPO水平明显升高.外套膜中,2.5 mg.L-1下SOD活性受到持续诱导,其他浓度组则先被抑制,后随曝露时间延长逐渐被诱导;各浓度组CAT的变化波动较大,没有明显规律;而LPO水平明显升高.净化恢复阶段,12.5和62.5 mg.L-1DBP胁迫下的内脏团SOD和CAT活性恢复较慢,其LPO水平随时间延长逐渐恢复至对照组水平;外套膜中SOD活性呈持续升高趋势,CAT活性和LPO水平则随时间延长恢复到对照组水平.     

In vitro studies of the rabbit immune system. IV. Differential mitogen responses of isolated T and B cells.

The mitogenic responses of separated rabbit lymphocyte populations functionally analogous to mouse T and B cells have been tested in vitro. Purified T cells were prepared by passage over nylon wool (NW) and purified B cells prepared by treatment with antithymocyte serum and complement (ATS + C). ATS + C kills 70% of peripheral blood lymphocytes (PBL's) and 50% of the spleen cells while passage over NW yields 40% of the applied PBL's and 5–23% of the applied spleen cells. NW-purified T cells from the spleen or PBL's respond fully to concanavalin A (Con A) but have a reduced response to phytohemaglutinin (PHA) and little or no response to goat anti-rabbit immunoglobulin (anti-Ig). PBL's that survive ATS + C (B cells) are stimulated by anti-Ig but not by Con A or PHA. B cells purified from spleen do not respond to Con A or PHA but will respond to anti-Ig under appropriate conditions. A full spleen B-cell response to anti-Ig required removal of Ig produced by the cultures that blocked anti-Ig stimulation. It is concluded that, for rabbit lymphocytes, Con A and PHA are primarily T-cell mitogens and that anti-Ig is primarily a B-cell mitogen. However, the mitogen response of unfractionated PBL or spleen cell populations indicates an overlap in reactivity. This could be due to cells sharing T and B properties, alteration of cell populations by the fractionation procedures used, or recruitment of one population in the presence of a mitogenic response of the other population.     

X-ray induction of dominant lethals in late spermatids and mature spermatozoa of Drosophila melanogaster: the role of oxygenation

The role of oxygenation in determining the sensitivity to the induction of dominant lethals was examined in late spermatids and mature spermatozoa of Drosophila melanogaster. 0–2-h-old or 7-day-old Oregon-K males were irradiated with different X-ray exposures in nitrogen, air or in oxygen and the frequencies of dominant lethals induced in these stages were studied. The results obtained confirm and extend Sobels' earlier observations and the interpretation derived therefrom namely, that under normal conditions in air, mature spermatozoa are characterised by a higher degree of oxygenation than late spermatids and this difference is sufficient to explain the differential response of these stages. Similar Oxygen-Enhancement-Ratios(OERs) (of about 2) were obtained for both the cell stages. The present data also revealed that late spermatids are significantly less sensitive than mature spermatozoa to the X-ray-induction of dominant lethals in a nitrogen atmosphere. A plausible mechanism is suggested to explain this observation.     

Comparison of the inhibitory potential towards carbonic anhydrase,acetylcholinesterase and butyrylcholinesterase of chalcone and chalcone epoxide

Chalcones and chalcone epoxides are important synthetic intermediates in organic and medicinal chemistry. Chalcones possess a broad spectrum of biological activities; however, 1,3‐diphenyl‐2‐propenone or chalcone has not been given the attention it deserve as its substituted derivatives. In this study, the inhibition effects of chalcone and its epoxidated derivative chalcone epoxide against human carbonic anhydrase isozymes I and II (hCA I and hCA II), acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) were evaluated. The results obtained showed that both compounds exhibited potent inhibitory activity, with IC₅₀ values less than 10 µM. IC ₅₀ values in the submicromolar (hCA I and hCA II) to low micromolar range (AChE and BuChE) were observed for both compounds. The mechanism of inhibition and the inhibitory constants ( K _i values) for each compound were also determined. Furthermore, chalcone epoxide was docked within the active sites of hCA I, hCA II, AChE, and BuChE to explore its binding mode with the enzymes.