亚铁离子对水稻萌发后幼苗生长的促进作用

本文最新报道亚铁离子在远高于营养浓度的情况下（０．４４－７．１６ｍｍｏｌ／Ｌ）能显著促进水稻萌发后的幼苗生长,其效果与已报道的促进因子Ｃ２Ｈ４相当．在试验的１９种不同化合物中,发现只有ＦｅＳＯ４对萌发后水稻幼苗生长有显著的促进作用,并证明其有效成分为Ｆｅ（２＋）．这种促进作用在淹水的厌氧条件下和通气条件均能发生,但通气条件下促进程度稍低．水稻不同基因型对Ｆｅ（２＋）的反应无明显差异,可能这种促进作用是水稻适应水田厌氧环境的方式之一．高浓度乙烯（５０—１００ｐｐｍ）的促进作用与亚铁离子的效果相近．这一发现有助于提高水稻在淹水厌氧直播时的出苗率．－－ｓｉｇｎｉｆｉｃａｎｔａｔｌ％ｌｅｖｅｌ;＊－－ｓｉｇｎｉｆｉｃａｎｔａｔ５％ｌｅｖｅｌ;ｕｓ－－ｎｏｔｓｉｇｎｉｆｉｃａｎｔ．２．３ＥｆｆｅｃｔｏｆｖａｒｉｏｕｓＦｅ＋＋ｃｏｎｃｅｎｔｒａｈｏｎｓｏｎｔｈｅｓｅｅｄｌｉｎｇｇｒｏｗｔｈｏｆｒｉｃｅＴｗｏｇｅｎｏｔｙｐｅｓ,ｍｏｄｅｒｎＩＲ５０ａｎｄｔｒａｄｉｔｉｏｎａｌＡＳＤＩ,ｗｅｒｅｕｓｅｄｆｏｒｆｕｒｔｈｅｒｓｔｕｄｙ．Ｆｅ＋＋ｗｉｔｈｃｏｎｃｅｎｔｒａｔｉｏｎｓｆｒｏｍ０．４４ｔｏ７．１６ｍｍｏｌ／Ｌｗ     

鼎湖山植被演替过程中椎栗和荷木种群的动态

 森林群落的演替过程,是以各优势种群的动态为其表现特征的。本项研究系统地研究了鼎湖山森林植被演替过程各优势种群的动态。本文研究演替顶极建群种椎栗和荷木等阳生性种群的动态,结果表明其生态位宽度在演替过程中由入侵针叶林起逐渐开始增大,至阳生性为优势常绿阔叶树阶段时为最大,此后渐渐下降,但不会下降为零。在其演变过程中,这些阳生性的种群格局由集群分布演变为趋于随机分布;其与早期先锋种马尾松树种的生态位宽度重叠值和种间联结值由高向低转变,而与中生性树种却有较高的生态位重叠值和种间联结值,但这两方面的值在后期有减弱的趋向。这些结果一方面说明该种群的先锋特性,另一方面也说明由于成熟群落的循环更新使群落结构出现不均匀与镶嵌,使这些阳生性先锋种群 在演替的后期仍以一定数量存在。     

Na_2SO_3和NaHCO_3对叶绿体CF_1－ATPase活力作用的机制

Ｎａ２ＳＯ３对热－ＤＴＴ活化的游离ＣＦ１及类囊体膜上ＣＦ１－ＡＴＰａｓｅ活力均有显著的促进作用,ＮａＨＣＯ３亦有明显的促进作用。Ｎａ２ＳＯ３和ＮａＨＣＯ３的促进作用与它们解除Ｍｇ２＋的抑制作用有关。从ＮａＨＣＯ３和Ｎａ２ＳＯ３及它们与Ｍｇ２＋之间的竞争性关系,表明三者是结合在酶的同一部位上。Ｎａ２ＳＯ３可明显降低热－ＤＴＴ活化的游禹ＣＦ１－ＡＴＰａｓｅ催化反应的活化能,这可能与促进产物ＡＤＰ的释放有关。     

简便、快速提取高质量的RNA分子

MethodsforHandy,RapidIsolationofHighQualityRNAbyGuanadiumThioeyauateDuJianYuanYanhuaMaShenglinDongZhiwei(BeijingInstituteforCancerResearchBeijing100034)硫氰胍是一种有效的蛋白变性剂。早在1979年,Chirgwin等就利用氯化铯／硫氰胍超离心技术成功地从RNA酶富集的胰脏组织中提取出未降解的RNA分子[2],从而使它成为抑制RNA酶的首选药物并得到广泛使用,但受到超速离心设备的限制。1983年,Cathala报道了氯化锂／硫氰胍RNA提取法[1]。该方法操作简便,获得的RNA质量很高,但所需时间较长。为了能在短时间内更快…     

Characterization of cis-acting elements in light regulation of the nuclear gene encoding the A subunit of chloroplast isozymes of glyceraldehyde-3-phosphate dehydrogenase from Arabidopsis thaliana.

We have characterized cis-acting elements involved in light regulation of the nuclear gene (GapA) encoding the A subunit of chloroplast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in Arabidopsis thaliana. Our results show that a 1.1-kb promoter fragment of the GapA gene is sufficient to confer light inducibility and organ specificity in transgenic Nicotiana tabacum (tobacco) plants, using the beta-glucuronidase gene of Escherichia coli as the reporter gene. Deletion analysis indicates that the -359 to -110 bp region of the GapA gene is necessary for light responsiveness. Within this region there are three copies of a decamer repeat (termed the Gap box) having the consensus sequence 5'-CAAATGAA(A/G)A-3', which has not been characterized in the promoter regions of other light-regulated genes. A deletion (to -247) producing loss of one copy of these elements from the GapA promoter reduces light induction by two- to threefold compared with a promoter deletion (to -359) with all three Gap boxes present, while deletion of all three Gap boxes (to -110) abolishes light induction completely. Gel mobility shift experiments using tobacco nuclei as the source of nuclear proteins show that GapA promoter fragments that contain these repeats bind strongly to a factor in the nuclear extract and that binding can be abolished by synthetic competitors consisting only of a monomer or dimer of the Gap box. Furthermore, a trimer, dimer, and monomer of the Gap box show binding activity and, like the authentic GapA promoter-derived probes, show binding activities that are correlated with Gap box copy number. These results strongly suggest that these repeats play important roles in light regulation of the GapA gene of A. thaliana.     

含金地质体表生带中主要微生物类群的研究

通过对16个含金矿区主要微生物类群的分布、生态结构的研究,发现不同类型的金矿具有不同的微生物类群.金矿矿石与金矿酸水中的自养硫细菌和异养菌分布具有明显差异,酸性水中含自养硫细菌较多,含异养菌极少;金矿氧化带中的异氧菌一般多于自氧硫细菌,其优势菌以芽孢杆菌属中蜡状芽孢杆菌为主.研究结果揭示了金矿中存在的主要微生物类群,对阐明表生金的形成、成岩和蚀变作用具有一定的意义,对发掘生物湿法冶金菌种资源具有重要作用.     

Stomatal sensitivity to abscisic acid following water deficit stress

Short-and medium-term stresses (1 and 24 h, respectively) wereapplied to detached leaves of Commelina communis L., resultingin both cases in a final leaf cell water potential (     

Nanometric design of extraordinary hydrophobic-induced pKa shifts for aspartic acid: Relevance to protein mechanisms

Commonly a key element enabling proteins to function is an amino acid residue or residues with functional side chains having shifted pKa values. This article reports the results on a set of protein-based polymers (model proteins) that exhibit hydrophobic folding and assembly transitions, and that have been designed for the purpose of achieving large hydrophobic-induced pKa shifts by selectively replacing Val residues by Phe residues. The high molecular weight polypentapeptides, actually poly (tricosapeptides) with six varied pentamers in fixed sequence, were designed and synthesized to have the same amino acid compositions but different proximities between a single aspartic acid residue and 5 Phe residues per 30 residues. With the 5 Phe residues distal from the Asp residue, the observed pKa shift was 2.9 when compared to the Val-containing reference. With the 5 Phe residues within 1 nm of the Asp residue, the pKa shift was 6.2. This represents a free energy of interaction of 8 kcal/moles. To our knowledge, this is the largest pKa shift documented for an Asp residue in a polypeptide– or protein–water system. Data are reviewed that do not support the usual electrostatic arguments for pKa shifts of charge–charge repulsion and/or unfavorable ion self-energies arising from displacement of water by hydrophobic moieties, but rather the data are interpreted to indicate the presence of an apolar–polar repulsive free energy of hydration, which results from a potentially highly cooperative competition between apolar and polar species for hydration. © 1994 John Wiley & Sons, Inc.     

高原鼠兔季节性繁殖中的神经内分泌调控Ⅱ．不同光制对生殖恢复期的影响

本项研究将野外捕获的成年雄性高原鼠兔（Ｏｃｈｏｔｏｎａｃｕｒｚｏｎｉａｅ）分３组进行不同光制的饲养,以检验光周期对其神经内分泌─—生殖轴功能的影响：（１）长光照组睾丸及附属性腺的重量和血浆睾酮水平均明显高于自然光组（ｐ＜０．０５）和短光照组（ｐ＜０．０１）。（２）长光照组的松果腺重量（１．５±０．１毫克,ｎ＝１５）和褪黑激素含量（８９．７±５．８微微克／松果腺）,均显著低于其它两组。（３）自然光组和短光照组性腺的显著萌发表明,在高原鼠兔季节性繁殖的年周期中,其神经内分泌─—生殖轴对春分前短光照的抑制作用具有不应期。     

番木瓜环斑病毒复制酶(亚基)基因的克隆、序列分析及其植物表达载体的构建

近二年报道,在TMV^⑴、PVX^⑵、PEBV^⑶和CMV^⑷等病毒中,利用病毒编码的复制酶(亚基)基因或相关cDNA片段转化烟草,工程植株获得绝对或极高的病毒抗性。大量研究认为：马铃薯Y病毒组的核内含体大分子量蛋白(Nib)是依赖于RNA的RNA复制酶(或核心亚基),Nlb与上述病毒的复制酶有广泛的同源保守区^⑸。因此,Nib基因的克隆,不但在植物抗病基因工程方面,而且在马铃薯Y病毒组基因组的复制研究方面．均有重要的意义。本文以马铃薯Y病毒组的重要成员番木瓜环斑病毒的华南强株系(PRSV—sM)为材料,克隆了PRSV的Nib基因,并完成其全序列测定和植物表达载体的构建,为探索马铃薯Y病毒组复制酶可能介导的抗病性打下了基础。