绿豆子叶线粒体发育过程中腺苷酸的变化及其对细胞能量代谢的影响

本文研究了绿豆子叶线粒体发育过程中腺苷酸能荷(AEC)的变化及其和细胞能量状态的关系。观察到吸胀2小时的绿豆子叶线粒体发育不完全,吸胀12小时线粒体内膜出现明显的内嵴。随着线粒体完整性的增加,H~ -ATPase 的活性明显增大,细胞的 ATP 水平也明显提高,AMP 水平下降,AEC 值剧增,但此时线粒体本身的腺苷酸水平及 AEC 值变化不大。经1×10~(-4)mol/1和5×10~(-4)mol/1 DNP 处理的子叶,细胞中 ATP 含量大大降低,AMP 增多,AEC 随之下降,而线粒体的腺苷酸及 AEC 仍然保持衡定,腺苷酸激酶(AK)的活性不但不受 DNP 的抑制,反比对照增加约50%。线粒体能量状态的维持可能受 AK 的调节。     

核苷对ROS17/2.8细胞株腺苷酸环化酶活性的影响

 大鼠成骨肉瘤细胞株(ROS17/2.8)系甲状旁腺素(PTH)的靶细胞。当该细胞质膜上的PTH受体与PTH结合后,可激发腺苷酸环化酶(AC)的活性。腺苷及四种不同的核苷酸(AMP、GMP、UMP、CMP)单独对AC无明显效应,但却可抑制PTH对AC的刺激作用。而鸟苷或木糖腺苷则可显著增强PTH对AC的刺激作用。提示核苷的不同代谢物在代谢调节中的多样化作用。     

寡腺苷酸合成酶家族蛋白调控抗病毒天然免疫应答的研究进展

寡腺苷酸合成酶(Oligoadenylate synthetase,OAS)家族蛋白是典型的抗病毒蛋白,其家族成员寡腺苷酸合成酶1～3(OAS1～3)和寡腺苷酸合成酶样蛋白(Oligonucleotide synthase-like protein synthetase,OASL)在抗病毒天然免疫应答中发挥着重要作用。病毒感染机体后,细胞分泌的干扰素(Interferon,IFN)会诱导寡腺苷酸合成酶家族蛋白合成,其可通过核糖核酸酶L(RNase L)依赖途径和非依赖途径发挥抗病毒作用。本综述主要讨论寡腺苷酸合成酶家族蛋白的抗病毒机制与抗病毒临床应用的相关研究进展。     

不同生长调节物质对水稻生长及镉积累的影响

比较脱落酸(ABA)、乙烯利(ETH)、水杨酸(SA)和茉莉酸甲酯(MeJ A)4种植物生长调节物质(PGR)对水稻生长及籽粒镉(Cd)积累的影响差异。试验采用重金属污染土种植水稻,于分蘖期、灌浆期各进行1次PGR叶面喷施处理,分析灌浆期叶片光合指标,丙二醛(MDA)含量以及收获期各部位生物量和Cd含量。结果表明:(1)低浓度ABA(5mg/L)可维持水稻正常产量;高浓度ABA(15mg/L)则导致产量下降。ETH对水稻地上部生长和单株产量有显著抑制作用,SA和MeJ A(0.56mg/L)均可保证地上部正常生长,维持正常产量。(2)外施4种PGR均抑制灌浆期叶片气孔开放,降低蒸腾速率和光合速率,抑制效果最明显的是高浓度MeJ A(0.56mg/L)。(3)在供试浓度范围内SA、低浓度ABA(5mg/L)以及高浓度MeJ A均可降低灌浆期叶片MDA含量,减少质膜过氧化水平。(4)4种PGR均可降低水稻籽粒Cd含量,其中低浓度ABA(5mg/L)抑制籽粒Cd积累的效应最佳。相关性分析结果表明,PGR抑制籽粒积累Cd的效应与地上部向籽粒转运Cd的调控机制有关,与蒸腾速率无显著相关关系。(5)综上所述,低浓度ABA(5mg/L)处理对水稻产量无影响,且籽粒Cd含量降低程度最大。适当浓度的PGR可降低水稻籽粒Cd含量,在中低度重金属污染农田生态修复实践中具有一定的应用前景,但必须精确控制PGR的处理时间和处理浓度,避免出现抑制生长和降低产量的负效应。     

环腺苷酸(cAMP)对粗柄羊肚菌菌丝生长和菌核发生的影响

通过外源添加环腺苷酸(cAMP)、腺苷酸环化酶激活剂氟化钠(NaF)和cAMP降解产物腺苷酸(AMP),研究了cAMP对粗柄羊肚菌菌丝生长和菌核发生的影响,并测定了不同菌核发育阶段培养物的胞内cAMP浓度。结果表明:在测试浓度范围内,cAMP对粗柄羊肚菌菌丝生长影响不显著,但显著抑制该真菌菌核的发生。菌核数量与外源添加的cAMP和NaF具有明显的剂量负相关性。然而,AMP显著促进粗柄羊肚菌菌丝生长,却没有明显影响其菌核发生。培养物胞内cAMP浓度随着培养时间的延长而增加,与外源添加cAMP抑制菌核发生的结果一致。本研究为羊肚菌菌核发生的分子机制研究提供理论支持。     

Cd对不同种类植物生长和养分积累的影响

溶液培养法研究了不同活度Cd2 对4种植物卷心菜、黑麦草、玉米和白三叶草生长和养分积累的影响．结果表明,随Cd2 活度增加,4种植物的生长速率和干物质产量均下降．白三叶草对Cd2 最敏感;黑麦草和玉米耐性较强;卷心菜在高ACd2 时敏感．Cd2 对Fe、Mn、Cu、Zn、Ca、Mg、P、S等养分积累的影响因植物种类而异．Cd2 降低Fe、Mn、Cu、Zn、Ca、Mg等的积累．P在4种植物中和S在除卷心菜外的3种植物中的积累比对照增加．卷心菜和白三叶草对Cd毒敏感性差异与Fe、Mn、Ca、Mg的积累受Cd2 影响程度不同密切相关．     

BA对花生叶片腺苷酸含量和能荷的影响

去顶去根花生幼苗库叶（上位叶）经１０＾－５ｍｏｌ／Ｌ ＢＡ涂抹处理１２ｈ和４８ｈ时,库叶ＡＴＰ含量增加,分别高于对照１９．４％和３３．１％。ＡＤＰ含量在处理后１２－３６ｈ,不断增加,以后逐渐降低,接近对照水平,ＢＡ处理库叶减少ＡＭＰ含理。ＢＡ促进库叶能荷值增加,调节总腺苷酸含量的动态变化。ＢＡ处理库叶１２ｈ,叶片组织和线粒体呼吸速率增加,加强了线粒体氧化磷酸化和能量传递的过程。     

低压缺氧对大鼠脑线粒体腺苷酸转运体特性的影响

本文探讨低压缺氧对大鼠脑线粒体内膜腺苷酸转运体（adenine nucleotide translocator,ANT）转运特性的影响。实验将雄性Wistar大鼠随机分为常氧对照组和缺氧组,后者分别连续暴露于模拟5000m高原1、5、15、30d（23h／d）。分别于平原和模拟4000m高原断头处死动物,分离脑线粒体,用抑制剂终止法测定线粒体对。H-ADP的转运效率,抑制剂滴定法测定ANT密度,HPLC测定线粒体内腺苷酸含量。结果显示：缺氧后ANT转运活性均明显低于常氧组,缺氧不同天数线粒体内膜ANT分布密度无显著改变,线粒体内（ATP＋ADP）含量下降与转运活性变化一致。以上观察结果表明,低压缺氧暴露可显著抑制ANT转运活性,降低能量产生和利用的周转率,但不改变ANT密度,提示ANT活性改变是低压缺氧时细胞能量代谢障碍的重要机制。     

外源一氧化氮供体对几种植物种子的萌发和幼苗生长的影响

以0、0.1、0.3、0.5、0.7、0.9mmol·L-1共6种浓度的外源一氧化氮(NO)供体硝普钠(SNP)处理豌豆、黄瓜、玉米和刺槐种子及其砂培幼苗后的结果表明:0.1～0.3mmol·L-1SNP对种子发芽势、发芽率及幼苗的根长、叶绿素含量和生物量有明显的促进作用;随着SNP浓度的增加,种子萌发和幼苗生长明显受抑制,不同植物受抑制程度的差异明显.     

镉和增强紫外线-B辐射复合作用对大豆生长的影响

研究了Cd^2+和增强紫外线-B(UV-B)辐射以及二者复合胁迫(Cd+UV-B)对大豆生长、光合作用、抗氧化酶活性和吲哚乙酸(IAA)氧化酶活性的影响,结果表明,UV-B辐射对大豆生长较CA^2+有更明显的抑制作用,主要是降低了光合作用,生物量减小;抑制节间的分化和伸长,节间减少,株高降低。UV-B辐射对POD、SOD活性有显著诱导作用,而Cd^2+明显颉颃UV-B对POD活性的诱导并抑制IAA氧化酶活性．在复合作用下,植物体内IAA氧化酶和POD活性较UV-B单独作用下显著降低,这两种酶活性降低会引起植物体内IAA含量升高,同时光合作用略有升高,这是株高和生物量较UV-B作用下有所增加的重要原因,复合胁迫还增强了对根伸长生长的抑制作用,根长度较对照显著降低(P<0．05)。IAA氧化酶和POD活性变化以及光合强度变化与大豆株高和生物量变化密切相关,这也是复合胁迫影响大豆生长状况的重要因素。     

Extraction, purification, identification and metabolism of 3'',5''-cyclic UMP, 3'',5''-cyclic IMP and 3'',5''-cyclic dTMP from rat tissues.

The large-scale extraction and partial purification of endogenous 3',5'-cyclic UMP, 3',5'-cyclic IMP and 3',5'-cyclic dTMP are described. Rat liver, kidney, heart, spleen and lung tissues were subjected to a sequential purification procedure involving freeze-clamping, perchlorate extraction, alumina and Sephadex ion-exchange chromatography and preparative electrophoresis. The samples thus obtained co-chromatographed with authentic cyclic UMP, cyclic IMP and cyclic dTMP on t.l.c. and h.p.l.c. and the u.v. spectra of the extracted samples were identical with those of the standards. Fast atom bombardment of the three cyclic nucleotide standards yielded mass spectra containing a molecular protonated ion in each case; mass-analysed ion kinetic-energy spectrometry ('m.i.k.e.s') of these ions produced a spectrum unique to the parent cyclic nucleotide. The extracted putative cyclic UMP, cyclic IMP and cyclic dTMP each produced a m.i.k.e.s. identical with that obtained with the corresponding cyclic nucleotide standard. Rat liver, heart, kidney, brain, intestine, spleen, testis and lung protein preparations were each found capable of the synthesis of cyclic UMP, cyclic IMP and cyclic dTMP from the corresponding nucleoside triphosphate, of the hydrolysis of these cyclic nucleotides and of their binding, with the exception that cyclic dTMP was not synthesized by the kidney preparation.     

Absolute configuration of Rp-uridine 3'',5''-cyclic phosphorothioate.

Triethylammonium uridine-3',5'-cyclic phosphorothioate crystallizes in space group P2(1)2(1)2(1), a = 7.177(1), b = 13.155(6), c = 21.114(7) A, C15H26N3O7PS, MW 423.4, Z = 4, dx = 1.41g/cm3. The crystal structure was solved by direct methods on the basis of 1493 counter X-ray diffraction data (CuK alpha) and refined to R = 5.1%. The configuration of the thiophosphate group is Rp; conformational parameters are: glycosyl torsion angle anti, -151.9(5) degrees, sugar pucker C(3')-endo with P = 27.3 degrees, vmax = 45.5 degrees, six-membered cycle in chair form. The bond distances in the non-esterified P-S and P-O suggest that the negative charge is distributed between the groups. As illustrated in this and other studies, P-O has a much higher affinity for hydrogen bonds than P-S, indicated here by interactions with triethyl-ammonium N-H and O(2')-H as donors. One additional hydrogen bond N(3)-H---0(4) ties the bases which form a ribbon-like structure. 0(2) and S are not engaged in hydrogen bonds. The triethylammonium ion is two-fold disordered.     

Adenosine 3'':5''-cyclic monophosphate in higher plants: Isolation and characterization of adenosine 3'':5''-cyclic monophosphate from Kalanchoe and Agave.

The activity of the putative ketogenic beta-oxoacyl-CoA thiolase from mitochondria of rat liver increases with starvation, during neonatal life, and after the injection of glucagon. These changes are associated with alteration in ketonaemia. The changes in activities of this species of thiolase are not associated with significant alterations in the apparent affinity (Km) for the ketogenic substrate, acetyl-CoA. These results support a role for thiolase in the regulation of ketogenesis.     

Guanosine 3'',5''-cyclic monophosphate and the in vitro physiology of frog photoreceptor membranes

Frog rod outer segments freshly detached from dark-adapted retinas contain approximately 1-2 molecules of guanosine 3',5'-cyclic monophosphate (cyclic GMP) for every 100 molecules of visual pigment present. This cyclic GMP decays to 5'-GMP, and the conversion is accelerated upon illumination of the outer segments. Bleaching one rhodopsin molecule can lead to the hydrolysis of 1,000-2,000 molecules of cyclic GMP within 100-300 ms. The decline in cyclic GMP concentration becomes larger as illumination increases, and varies with the logarithm of light intensity at levels which bleach between 5 X 10(2) and 5 X 10(5) rhodopsin molecules per outer segment-second. Light suppression of plasma membrane permeability, assayed in vitro as light suppression of outer segment swelling in a modified Ringer's solution, occurs over this same range of light intensity. The correlation between cyclic GMP and permeability or swelling is maintained in the presence of two pharmacological perturbations: papaverine, a phosphodiesterase inhibitor, increases both cyclic GMP levels and the dark permeability of the plasma membrane; and beta,gamma-methylene ATP increases the effectiveness of light in suppressing both permeability and cyclic GMP levels.