Kinetics of carbon monoxide binding to singly reduced human methemoglobin

The kinetics of reaction of singly reduced methemoglobin (HbFe3(3+)Fe2+) with carbon monoxide have been investigated by the pulse radiolysis method. The rate constant for carbon monoxide binding to this form of hemoglobin is 4.1 X 10(6) M-1 S-1 at 24 degrees in our solutions. This value compares with existing values for various forms of hemoglobin ranging from 4 X 10(6) to 6.5 X 10(6) M-1 S-1. Addition of inositol hexaphosphate to the solutions results in a lower rate constant for carbon monoxide binding amounting to 1.1 X 10(5) M-1 S-1.     

Sexual Selection in the Three-Spined Stickleback

The purpose of this study was to seek evidence for the influence of sexual selection on both male and female three-spined sticklebacks, a species in which the ♂ alone has parental responsibilities. We studied the intrasexual relationships of ♂♂ and ♀♀ prior to courtship, and the intrasexual and intersexual relationships of both sexes during courtship. Results demonstrated that both ♂♂ and ♀♀ compete intrasexually, and suggested that both sexes are discriminative in mate selection. These results are compatible with Trivers' (1972) model of the role of parental investment in sexual selection.     

A proton nuclear magnetic resonance investigation of proximal histidyl residues in human normal and abnormal hemoglobins. A probe for the heme pocket.

Proton nuclear magnetic resonance spectroscopy at 250 MHz has been used to investigate the conformations of proximal histidyl residues of human normal adult hemoglobin, hemoglobin Kempsey [beta 99(G1) Asp leads to Asn], hemoglobin Osler [beta 145(HC2) Tyr leads to Asp], and hemoglobin McKees Rocks [beta 145(HC2) Tyr leads to Term] around neutral pH in H2O at 27 degrees C, all in the deoxy form. Two resonances that occur between 58 and 76 ppm downfield from the water proton signal have been assigned to the hyperfine shifted proximal histidyl NH-exchangeable protons of the alpha- and beta-chains of deoxyhemoglobin. These two resonances are sensitive to the quaternary state of hemoglobin, amino acid substitutions in the alpha 1 beta 2-subunit interface and in the carboxy-terminal region of the beta-chain, and the addition of organic phosphates. The experimental results show that there are differences in the heme pockets among these four hemoglobins studied. The structural and dynamic information derived from the hyperfine shifted proximal histidyl NH-exchangeable proton resonances complement that obtained from the ferrous hyperfine shifted and exchangeable proton resonances of deoxyhemoglobin over the spectral region from 5 to 20 ppm downfield from H2O. The relationship between these findings and Perutz's stereochemical mechanism for the cooperative oxygenation of hemoglobin is discussed.     

Forskolin as a novel lipolytic agent

Forskolin is a novel lipolytic agent which elevates cAMP and FFA release in rat adipocytes in a manner different from existing lipolytic factors. This effect of Forskolin is potentiated by all lipolytic hormones tested, i.e. epinephrine, ACTH, and glucagon and is also reversible. The same batch of adipocytes can be repeatedly stimulated after washing. The effective concentration of Forskolin is in the micromolar range. Its action is due to an activation of cAMP synthesis by adenylate cyclase. There is no effect on cAMP hydrolysis. In contrast to stimulation by lipolytic hormones, Forskolin-activated membrane adenylate cyclase was not further stimulated by GPP(NH)P. These results suggest that Forskolin may be a useful analytical agent in the study of adenylate cyclase mediated function in intact adipocytes.     

油菜种子发育早期的油体发生与调控

以甘蓝型油菜（Brassica napus L.）品种‘Westar’和‘Topas’为材料,通过超微结构观察和荧光定量PCR技术对油菜胚胎发育早期油体的发生、油体蛋白及脂肪酸合成转录因子基因的表达情况进行分析。结果显示：油体出现在油菜胚胎发育早期,在授粉9~11 d后（球形胚时期）的胚体和胚柄中均存在直径小于0.5 μm的油体;荧光定量实验结果表明,除BnCLO3的表达量在整个胚胎发育阶段无明显变化外,其他油体蛋白基因Oleosins、Steroleosins和BnCLO1的表达量在心形胚时期就明显增多并持续增长;脂肪酸合成转录因子BnLEC1、BnL1L、BnWRI1和BnFUS3在胚胎发育阶段,基因表达规律均呈先上升再下降的趋势,但达到最高值的时间存在差异,其中BnLEC1最早,BnL1L其次,BnWRI1和BnFUS3较晚。研究结果表明甘蓝型油菜在球形胚时期出现油体,其结构蛋白和转录调控因子基因的表达自心形胚开始明显增多。     

火龙果转录组测序、基因表达与功能分析

利用高通量测序技术对火龙果（Hylocereus undulatus Britt）红肉品种‘大红二号’的花芽、果实和枝条不同发育阶段的基因表达进行研究。结果显示,转录组测序共获得468.68 Gb原始数据（Raw data）,从头组装获得239 152条转录本和162 519条unigene,约53.74%的unigene得到注释。分别在43 506条和16 251条unigene中检测到600 283个SNP位点和56 147个SSR位点。基因表达分析结果表明,在火龙果不同组织Fl510、Fl513、Fl514、Fl518、F711、F715、S513、S419中分别有31、7、5、152、17、63、17、8个特异表达的unigene。通过GO和KEGG富集分析,发现了一些组织特异的GO条目和代谢通路,如在Fl510中富集的类萜骨架生物合成代谢通路等。本研究还对参与花发育的候选基因进行了鉴定和表达分析,他们包括COL基因、FT-like基因、分生组织决定基因和器官决定基因等。     

木犀科植物叶绿体基因组结构特征和系统发育关系

木犀科11属19个种叶绿体基因组的一般特征和变异特征的比较分析显示, 结果表明, 该科叶绿体基因组大小为154-165 kb, 其差异主要是大单拷贝(LSC)长度的差异所致。Jasminum属3个物种的叶绿体基因组长度与其余物种有较大差异, 该属clpP基因内含子和accD基因丢失。共线性分析表明, Jasminum属3个物种多个基因出现基因重排现象, 倒位可能是重排的主要原因。Jasminum属在IRb/SSC和SSC/IRa边界的基因均与其它物种不同; 重复序列与SSR数量检测结果表明, Jasminum属与其余物种在数量及重复长度上差异较大。基于CDS数据构建的系统发育树表明, Abeliophyllum distichum和Forsythia suspensa为木犀科中较早分化的类群。     

Enzymatic properties of human glucuronyltransferase and a sensitive method for its assay in a stable B lymphocyte cell line

Properties of lymphocyte glucuronyltransferase were studied in homogenates of SN1006 cells. A sensitive assay procedure for lymphocyte glucuronyltransferase was developed utilizing radioactive testosterone as the acceptor substrate and TLC for separation of the metabolite. The method is capable of detecting picomolar quantities of the product. The enzyme activity exhibited a broad pH optimum, and was subject to activation by the detergent Lubrol WX and Mn++ ions. The activity conformed to the Michaelis-Menten kinetics giving apparent Km values of 0.8 mM and 11 microM, for UDPGA and testosterone, respectively. 4-Methylumbelliferone, a-naphthol and p-nitrophenol behaved as competitive inhibitors of testosterone glucuronidation. The results indicate that the method could be used for genetic studies of human lymphocyte glucuronyltransferase, and that the enzyme is of consequence in detoxication of exogenous as well as endogenous substrates.     

黄腐酸增强小麦抗旱能力的生理生化机制初探

叶面喷施黄腐酸可显著提高小麦幼苗的保水能力,表现为降低叶面蒸腾强度,增加气孔扩散阻力,提高幼苗的生物量,在干旱条件下尤为明显。喷施黄腐酸可使干旱条件下叶片内脯氨酸含量提高近一倍,并在水分充足时,也能使叶片脯氨酸含量增加78%。     

茶尺蠖人工饲料的研究

本报道饲养茶尺蠖(Ectropis obliqua hypulina Wehrli)的5种人工饲料及其饲养方法．5种人工饲料均可用于大规模饲养一代幼虫．其中62号配方可用于续代饲养,在实验室内饲养5代的结果表明。效果良好．在饲料成分的加工．配制及饲养方法等方面．较前人有相当大的改进,因而叶因子用量减少,幼虫历期缩短．用人工饲料饲养的幼虫历期为13-20天。基本接近以茶叶饲养的对照(11—18天)．实验结果还表明饲料含水量．饲养方法．饲养密度和添加饲料的次数不同,对茶尺蠖的生长发育有明显的影响．初龄幼虫用平面培养基倒置饲养和高龄幼虫用片状饲料正置饲养为最佳方法．