Isolation of mitochondrial DNA sequences that distinguish male-sterility-inducing cytoplasms in Sorghum bicolor (L.) Moench

We have demonstrated that sorghum DNA sequences of mitochondrial origin can be used to distinguish different male-sterility-inducing cytoplasms. Six DNA clones containing single-copy mitochondrial sequences were hybridized on Southern blots to restriction enzyme-digested DNA of 28 sorghum lines representing sources of different cytoplasmic male-sterility (CMS) groups. Four cytoplasmic types were defined on the basis of the pattern of DNA fragments detected. Similar analyses of 50 additional diverse sorghum accessions suggested that three of the four cytoplasmic types may be diagnostic for CMS. Also, three other cytoplasmic types were discovered. These and other mitochondrial DNA clones may be useful molecular tools for “fingerprinting” sterility-inducing cytoplasms in breeding programs, determining cytoplasmic diversity among germ plasm accessions, and identifying new sources of cytoplasm that induce male sterility.     

Vero细胞毒素大肠菌（VTEC）的分离及表型和分子生物学特性的研究

２６株Ｖｅｒｏ细胞毒素（ＶＴ）阳性大肠菌,经分子生物学鉴定表明,其中１４株与ＥＨＥＣ探针杂交阳性,按Ｌｅｖｉｎｅ等的标准判定属产Ｖｅｒｏ细胞毒素大肠菌（ＶＴＥＣ）,其血清型为Ｏ_１５７：Ｈ_７３株（血便２株,脓血便１株）,Ｏ_２５７ＮＭ３株（血便１株,腹泻牛便２株）,Ｏ_２９样便１株）;其余１２株虽ＶＴ毒素阳性,但ＥＨＥＣ探针阴性,按标准判定尚难确认,有待进一步研究。     

Characterization of mechanosensitive channels in Escherichia coli cytoplasmic membrane by whole-cell patch clamp recording

Whole-cell patch clamp recordings were done on giant protoplasts of Escherichia coli. The pressure sensitivity of the protoplasts was studied. Two different unit conductance mechanosensitive channels, 1100 ± 25 pS and 350 ± 14 pS in 400 mm symmetric KCl solution, were observed upon either applying positive pressure to the interior of the cells or down shocking the cells osmotically. The 1100 pS conductance channel discriminated poorly among the monovalent ions tested and it was permeable to Ca²⁺ and glutamate^?. Both of the two channels were sensitive to the osmotic gradient across the membrane; the unit conductances of the channels remained constant while the mean current of the cell was increased by increasing the osmotic gradient. Both of the channels were voltage sensitive. Voltage-ramp results showed that the pressure sensitivity of protoplasts was voltage dependent: there were more channels active upon depolarization than hyperpolarization. The mech anosensitive channels were reversibly blocked by gadolinium ion. Also they could reversibly be inhibited by protons. Mutations in two of the potassium efflux systems, KefB and KefC, did not affect the channel activity, while a null mutation in the gene for KefA changed the channel activity significantly. This indicates a potential modulation of these channels by KefA.     

Regulation of phospholamban and troponin-I phosphorylation in the intact rat cardiomyocytes by adrenergic and cholinergic stimuli: roles of cyclic nucleotides,calcium, protein kinases and phosphatases and depolarization

Protein phosphorylation was investigated in [³²P]-labeled cardiomyocytes isolated from adult rat heart ventricles. The -adrenergic stimulation (by isoproterenol, ISO) increased the phosphorylation of inhibitory subunit of troponin (TN-I), C-protein and phospholamban (PLN). Such stimulation was largely mediated by increased adenylyl cyclase (AC) activity, increased myoplasmic cyclic AMP and increased cyclic AMP dependent protein kinase (A-kinase)-catalyzed phosphorylation of these proteins in view of the following observations: (a) dibutyryl-and bromo-derivatives of cyclic AMP mimicked the stimulatory effect of ISO on protein phosphorylation while (b) Rp-cyclic AMP was found to attenuate ISO-dependent stimulation. Unexpectedly, 8-bromo cyclic GMP was found to markedly increase TN-I and PLN phosphorylation. Both ₁- and ₂-adrenoceptors were present and ISO binding to either receptor was found to stimulate myocyte AC. However, the stimulation of the ₂-AR only marginally increased while the stimulation of ₁-AR markedly increased PLN phosphorylation. Other stimuli that increase tissue cyclic AMP levels also increased PLN and TN-I phosphorylation and these included isobutylmethylxanthine (non-specific phosphodiesterase inhibitor), milrinone (inhibits cardiotonic inhibitable phosphodiesterase, sometimes called type III or IV) and forskolin (which directly stimulates adenylyl cyclase). Cholinergic agonists acting on cardiomyocyte M₂-muscarinic receptors that are coupled to AC via pertussis toxin(PT)-sensitive G proteins inhibited AC and attenuated ISO-dependent increases in PLN and TN-I phosphorylation. Thein vivo PT treatment, which ADP-ribosylated G_i-like protein(s) in the myocytes, markedly attenuated muscarinic inhibitory effect on PLN and TN-I phosphorylation on one hand and, increased the -adrenergic stimulation, on the other. Controlled exposure of isolated myocytes to N-ethyl maleimide, also led to the findings similar to those seen following the PT treatment. Exposure of myocytes to phorbol, 12-myristate, 13-acetate (PMA) increased the protein phosphorylation, augmenting the stimulation by ISO, and such augmentation was antagonized by propranolol suggesting modulation of the -adrenoceptor coupled AC pathway by PMA. Okadaic acid (OA) exposure of myocytes also increased protein phosphorylation with the results supporting the roles for type 1 and 2A protein phosphatases in the dephosphorylation of PLN and TN-I. Interestingly OA treatment attenuated the muscarinic inhibitory effect which was restored by subsequent brief exposure of myocytes to PMA. While the stimulation of alpha adrenoceptors exerted little effect on the phosphorylation of PLN and TN-I, inactivation of alpha adrenoceptors by chloroethylclonidine (CEC), augmented -adrenergically stimulated phosphorylation. KCl-dependent depolarization of myocytes was observed to potentiate ISO-dependent increase in phosphorylation (incubation period 15 sec to 1 min) as well as to accelerate the time-dependent decline in this phosphorylation seen upon longer incubation. Verapamil decreased ISO-stimulated protein phosphorylation in the depolarized myocytes. Depolarization was found to have little effect on the muscarinic inhibitory action on phosphorylation. Prior treatment of myocytes with PMA, was found to augment ISO-stimulated protein phosphorylation in the depolarized myocytes. Such augmented increases were completely blocked by propranolol. Forskolin also stimulated PLN and TN-I phosphorylation. Prior exposure of myocytes to forskolin followed by incubation in the depolarized and polarized media showed that PLN was dephosphorylated more rapidly in the depolarized myocytes. The results support the view that both cyclic AMP and calcium signals cooperatively increase the rates of phosphorylation of TN-I and PLN in the depolarized cardiomyocytes during -adrenergic stimulation. The results raise the additional possibility that the calcium signal may regulate the dephosphorylation of PLN in the depolarized cell. While muscarinic attenuation of -adrenergic action on protein phosphorylation was mediated, in part, by decreased AC activity, and muscarinic inhibition of AC and protein phosphorylation was not detectably influenced by the depolarization, the evidence was seen that muscarinic stimulation of dephosphorylation mechanisms are intimately involved. The postulate that the simultaneous stimulation of ₁-adrenoceptors inhibits -adrenergic stimulation of PLN and TN-I phosphorylation is supported.     

为害枣树一菱纹叶蝉新种

为害枣树一菱纹叶蝉新种蔡平（安徽农学院园艺系合肥２３００３６）崔士英（河北师范大学生物系石家庄０５００１６）葛钟麟（安徽农学院植保系合肥２３００３６）菱纹叶蝉属（Ｈｉｓｈｉ。。ｏｎｕｓＩｓｈｉｈａｒａ。１９５３）隶属于同翅目（ＨｏｍｏＰｔｅｒａ）ｎ十...     

phbB,phbC基因克隆,序列分析及植物表达载体的构建

利用聚合酶链式反应技术,从真养产碱杆菌Ａｌｃａｌｉｇｅｎｅｓ ｅｕｔｒｏｐｈｕｓ Ｈ１６染色体ＤＮＡ中的主增并克隆了调控聚－β－羧基丁酸生物合成的两个关键酶基因;依赖ＮＡＤＰＨ的乙酰乙酰ＣｏＡ还原酶基因和ＰＨＢ合成酶基因。限制性内切酶图谱和核苷酸序列分析证实了克隆结果,并表明所克隆的基因与国外报道的有很高的同源性。     

Localization of binding site for encephalomyocarditis virus RNA polymerase in the 3'-noncoding region of the viral RNA.

We previously showed that encephalomyocarditis (EMC) virus RNA-dependent RNA polymerase (3Dpol) binds specifically to 3'-terminal segments of EMC virus RNA. This binding, which depends on both the 3'-noncoding region (3'-NCR) and 3'-poly (A) tail [together denoted 3'-NCR(A)], may be an important step in the initiation of virus replication. In this paper, the 3'-NCR and 3'-poly(A) were separately transcribed then mixed, but no complex with 3Dpol was obtained, showing that covalent attachment of the 3'-poly(A) to the 3'-NCR is essential for complex formation. Mutational and deletion analyses localized a critical determinant of 3Dpol binding to a U-rich sequence located 38-49 nucleotides upstream of the 3'-poly(A). Similar analyses led to the identification of a sequence of A residues between positions +10 and +15 of the 3'-poly(A) which are also critical for 3Dpol binding. As U-rich and A-rich regions are important for 3Dpol binding, a speculative model is proposed in which 3Dpol induces and stabilizes the base-pairing of the 3'-poly(A) with the adjacent U-rich sequence to form an unusual pseudoknot structure to which 3Dpol binds with high affinity.     

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。