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．     

[B10,22-Asp,B25-Tyr-NH2]-去β链C端五肽胰岛素的合成和性质

本文报道了[B10,22-Asp,B25-Tyr-NH2]-去B链羧端五肽胰岛素的制备及其生物活性。结果表明,这一类似物的生物活力比去五肽胰岛素(DPI)的活力高一倍,但却比Gerald所报道的[B10-Asp,B25-Tyr-NH_2]-DPI的活力低很多,说明后者的高活性可能依赖于分子中B22-Arg的存在。     

双拷贝人α型心钠素基因的组建及大肠杆菌分泌型克隆与表达

将单拷贝人α心钠素基因3′端用Ban Ⅱ酶解除去包括终止密码在内的36个碱基对,代之以人工合成的含Glu-Lys-Phe-Glu连接片段与另一单拷贝人α心钠素基因的5′端串连成编码60肽的双拷贝心钠素基因,克隆于大肠杆菌分泌型表达载体pIN-Ⅲ-OmpA_2质粒中,表达生成60肽的双拷贝人α型心钠素衍生物,在信号肽的作用下分泌至胞膜间质并自动切割为60肽的外源基因产物。分子量约8K的表达产物用分子筛或超滤膜分离后再经HPLC纯化,表达产物具有明显的心钠素放免活性和舒张血管活性。     

寡聚脱氧核苷酸d(G-C)_3的激光喇曼谱及其分析

用改进的固相磷酰三酯法合成了oligo-d(G-C)_3。以氩离子激光为激发光源,波长488nm.,在室温条件下,分别测定了纯化后的oligo-d(G-C)_3和其组分单体5’-dGMP和5’-dCMP的激光喇曼谱。观察到被测定的物质在300-2500cm~(-1)频率区间,各自都有其特征的谱形和喇曼峰。5’-dGMP和5’-dCMP谱中大多数特征峰在寡聚体的谱中消失,而在oligo-d(G-C)_3谱中出现了几处新的喇曼峰。经查证,峰832,851和899cm~(-1)系糖-磷酸主链的特征喇曼峰,另外几处峰与DNA的构象有关。实验结果表明oligo-d(G-C)_3在水溶液中(室温)主要以B-构象存在。     

Study on models of single populations: an expansion of the logistic and exponential equations

Using the adsorption theory of chemical kinetics, a new equation concerning the growth of single populations is presented:

$\text{d}\text{X}\text{d}\text{t}\text{=}\text{μ}{}_{\mathrm{c}}\text{X(1 ?)}\text{X}\text{X}{}_{\mathrm{m}}\text{1?}\text{X}\text{X}{}_{\mathrm{m}}{}^{\mathrm{\prime }}$

or in its integral form:

$\text{ln}\text{X}\text{X}{}_{\mathrm{o}}\text{?}\text{ln}\text{X}{}_{\mathrm{m}}\text{?X}\text{X}{}_{\mathrm{m}}\text{?X}{}_{\mathrm{o}}\text{+}\text{X}{}_{\mathrm{m}}\text{X}{}^{\mathrm{\prime }}{}_{\mathrm{m}}\text{X}{}_{\mathrm{m}}\text{?X}\text{X}{}_{\mathrm{m}}\text{?X}{}_{\mathrm{o}}\text{=μ}{}_{\mathrm{c}}\text{(t?t}{}_{\mathrm{o}}\text{)}$

This equation attempts to explain the relationship between population increment and limiting resources. It can be reduced to either the logistic or exponential equation under two extreme conditions. The new equation has three parameters, X_m, X′_m and μ_c, each of which has ecological significance. $\text{X}{}_{\mathrm{m}}\text{X′}{}_{\mathrm{m}}$ concerns the efficiency of nutrient utilization by an organism. Its value is between zero and one. With ratios approaching unity, the efficiency is high; lower ratios indicate that population increment is quickly restricted by limiting resources. μ_c, is a velocity parameter lying between μ_e, (exponential growth) and μ_L (logistic growth), and is dependent on the value of $\text{solX}{}_{\mathrm{m}}\text{X′}{}_{\mathrm{m}}$. From μ_c we can predict the time course of population incremental velocity ($\text{d}\text{X}\text{d}\text{t}$), and can observe that it is not symmetrical, unlike that derived from the logistic equation. At $\text{X}{}_{\mathrm{m}}\text{X′}{}_{\mathrm{m}}\text{= 1}$ the maximum velocity of the population increment predicted from the new equation is twice that of the logistic equation.Population growth in nature seems to support the new equation rather than the logistic equation, and it can be successfully fitted by means of a least square method.     

A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques

After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules.     

A mechanism coordinating root elongation,endodermal differentiation,redox homeostasis and stress response

Root growth relies on both cell division and cell elongation, which occur in the meristem and elongation zones, respectively. SCARECROW (SCR) and SHORT-ROOT (SHR) are GRAS family genes essential for root growth and radial patterning in the Arabidopsis root. Previous studies showed that SCR and SHR promote root growth by suppressing cytokinin response in the meristem, but there is evidence that SCR expressed beyond the meristem is also required for root growth. Here we report a previously unknown role for SCR in promoting cell elongation. Consistent with this, we found that the scr mutant accumulated a higher level of reactive oxygen species (ROS) in the elongation zone, which is probably due to decreased expression of peroxidase gene 3, which consumes hydrogen peroxide in a reaction leading to Casparian strip formation. When the oxidative stress response was blocked in the scr mutant by mutation in ABSCISIC ACID 2 (ABA2) or when the redox status was ameliorated by the upbeat 1 (upb1) mutant, the root became significantly longer, with longer cells and a larger and more mitotically active meristem. Remarkably, however, the stem cell and radial patterning defects in the double mutants still persisted. Since ROS and peroxidases are essential for endodermal differentiation, these results suggest that SCR plays a role in coordinating cell elongation, endodermal differentiation, redox homeostasis and oxidative stress response in the root. We also provide evidence that this role of SCR is independent of SHR, even though they function similarly in other aspects of root growth and development.     

Taxonomy and phylogeny of Ceriporia (Polyporales,Basidiomycota) with an emphasis of Chinese collections

Ceriporia accommodates a kind of wood-inhabiting polypores producing resupinate basidiocarps and causing a white rot. More than 30 species of this genus have been described; however, only a few species were referred to molecular phylogeny. In this study, a total of 203 specimens of Ceriporia were studied morphologically, and the ITS and/or nLSU regions from 42 samples, representing 18 species, were sequenced for phylogenetic analysis. Based on both morphological and phylogenetic analyses, three new species of Ceriporia, C. bubalinomarginata, C. pseudocystidiata and C. variegata, are described and illustrated. An annotated identification key is provided for all 20 species of this genus thus far known in China. Our phylogeny shows that (1) Ceriporia is not monophyletic, (2) C. spissa and C. viridans as morphologically circumscribed are polyphyletic, (3) C. inflata is retained for both C. inflata and C. jiangxiensis, and (4) presence or absence of hymenial cystidia is not a useful character in delimiting species relationships in Ceriporia.