用RAPD技术鉴定小麦属间不对称体细胞杂种

用随机引物扩增多态DNA(RAPD)技术对三种不同组合:小麦(Triticum aestivum)( )簇毛麦(Haynaldia villosa);小麦( )羊草(Leymus chinensis)和小麦( )高冰草(Agropyron elongatum)的属间不对称杂种进行分子鉴定,不同杂种植株的基因组经随机引物扩增后,均出现双亲的多态特异产物,证实它们含有双亲的基因组。将引物OPJ-12扩增的高冰草多态特异产物(分子量为0.77bp的DNA片段)分离纯化并标记作探针,用Southern杂交证明了小麦( )高冰草杂种经OPJ-12扩增的0.77kbp特异片段与高冰草这一片段具有同源性。本文结果证明,RAPD技术可作为小麦属间不对称体细胞杂种的一种快速、简便、有效的分子鉴定方法。     

草芍药,野牡丹和黄牡丹的核型研究

本文报道了国产芍药属(Paeonia L.)植物草芍药、野牡丹和黄牡丹的染色体数目及核型,均为2n=10=6m 2sm 2st,它们分别具2、3和4对次缢痕,所具次缢痕的数目和位置可以作三种核型的区别特征。     

Structural and functional studies of cross-linked Go protein subunits

The guanine nucleotide binding proteins (G proteins) that couple hormone and other receptors to a variety of intracellular effector enzymes and ion channels are heterotrimers of alpha, beta, and gamma subunits. One way to study the interfaces between subunits is to analyze the consequences of chemically cross-linking them. We have used 1,6-bismaleimidohexane (BMH), a homobifunctional cross-linking reagent that reacts with sulfhydryl groups, to cross-link alpha to beta subunits of Go and Gi-1. Two cross-linked products are formed from each G protein with apparent molecular masses of 140 and 122 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both bands formed from Go reacted with anti-alpha o and anti-beta antibody. The mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis is anomalous since the undenatured, cross-linked proteins have the same Stokes radius as the native, uncross-linked alpha beta gamma heterotrimer. Therefore, each cross-linked product contains one alpha and one beta subunit. Activation of Go by guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) does not prevent cross-linking of alpha to beta gamma, consistent with an equilibrium between associated and dissociated subunits even in the presence of GTP gamma S. The same cross-linked products of Go are formed in brain membranes reacted with BMH as are formed in solution, indicating that the residues cross-linked by BMH in the pure protein are accessible when Go is membrane bound. Analysis of tryptic peptides formed from the cross-linked products indicates that the alpha subunit is cross-linked to the 26-kDa carboxyl-terminal portion of the beta subunit. The cross-linked G protein is functional, and its alpha subunit can change conformation upon binding GTP gamma S. GTP gamma S stabilizes alpha o to digestion by trypsin (Winslow, J.W., Van Amsterdam, J.R., and Neer, E.J. (1986) J. Biol. Chem. 261, 7571-7579) and also stabilizes the alpha subunit in the cross-linked product. Cross-linked G o can be ADP-ribosylated by pertussis toxin. This ADP-ribosylation is inhibited by GTP gamma S with a concentration dependence that is indistinguishable from that of the control, uncross-linked G o. These two kinds of experiments indicate that alpha o is able to change its conformation even though it cannot separate completely from beta gamma. Thus, although dissociation of the subunits accompanies activation of G o in solution, it is not obligatory for a conformational change to occur in the alpha subunit.     

鸡马立克氏病病毒B抗原片段在大肠杆菌中表达

鸡马立克氏病病毒ＢａｍＨＩ基因文库Ｉ３质粒中含有编码Ｂ抗原膜外Ｄｏｍａｉｎ的ＤＮＡ序列。经ＳｃａＩ和ＳｐｈＩ双酶酶解Ｉ３质粒,分离获得７６４ｂｐＤＮＡ片段,并克隆进Ｍ１３ｍｐ１９中。ＤＮＡ序列测定分析表明克隆片段为ＭＤＶ－Ｂ抗原基因的４９４－１２５８ｂｐ部分序列。进一步分离ＮｃｏＩ－ＨｉｎｄＩＩＩ部分基因片（５３０ｂｐ）,克隆于ＰＬＰｒｏｍｏｔｅｒ控制下的含有修饰型ｃＩｔｓ８５７基因的表达载体中,     

氮磷钾配施对填充型烤烟烟碱含量的影响

以东北填充型烤烟品种"龙江911"为试验材料,通过正交回归田间试验,建立了氮、磷、钾肥与烤烟上部叶片烟碱含量的回归效应模型,并对各因子和交互作用进行了分析,模拟计算得出以降低上部叶片烟碱含量为目标的优化施肥方案.对模型解析表明,随施氮量增加,上部叶片烟碱含量呈先上升后下降趋势;随施磷量增加,烟碱含量呈上升趋势;随施钾量增加,烟碱含量呈急剧下降趋势.双因素效应大小依次为:氮钾＞磷钾＞氮磷,在一定范围内,氮磷、磷钾与烟碱含量表现为负相关,存在拮抗作用;而氮钾则相反,存在促进作用.对氮、磷、钾肥与烤烟上部叶片烟碱含量模型的综合分析得出:在植烟土壤为河淤土的生产区,烟田的基础施肥量建议为:氮肥33.5～47.8kg·hm-2,磷肥40.2～63.6 kg·hm-2,钾肥78.0～119.6kg·hm-2.     

中国距水虻属四新种(双翅目,水虻科)(英文)

记述我国距水虻属Allognosta 4新种,基黑距水虻A.basinigra sp.nov.,彩旗距水虻A.caiqiana sp.nov.,大龙潭距水虻A.dalongtana sp.nov.,梁氏距水虻A.liangi sp.nov.。模式标本保存在中国农业大学昆虫博物馆。     

Role of myosin light chain kinase in regulation of basal blood pressure and maintenance of salt-induced hypertension

Vascular tone, an important determinant of systemic vascular resistance and thus blood pressure, is affected by vascular smooth muscle (VSM) contraction. Key signaling pathways for VSM contraction converge on phosphorylation of the regulatory light chain (RLC) of smooth muscle myosin. This phosphorylation is mediated by Ca(2+)/calmodulin-dependent myosin light chain kinase (MLCK) but Ca(2+)-independent kinases may also contribute, particularly in sustained contractions. Signaling through MLCK has been indirectly implicated in maintenance of basal blood pressure, whereas signaling through RhoA has been implicated in salt-induced hypertension. In this report, we analyzed mice with smooth muscle-specific knockout of MLCK. Mesenteric artery segments isolated from smooth muscle-specific MLCK knockout mice (MLCK(SMKO)) had a significantly reduced contractile response to KCl and vasoconstrictors. The kinase knockout also markedly reduced RLC phosphorylation and developed force. We suggest that MLCK and its phosphorylation of RLC are required for tonic VSM contraction. MLCK(SMKO) mice exhibit significantly lower basal blood pressure and weaker responses to vasopressors. The elevated blood pressure in salt-induced hypertension is reduced below normotensive levels after MLCK attenuation. These results suggest that MLCK is necessary for both physiological and pathological blood pressure. MLCK(SMKO) mice may be a useful model of vascular failure and hypotension.     

Novel Bacillus thuringiensis δ-endotoxin active against Locusta migratoria manilensis

A novel δ-endotoxin gene was cloned from a Bacillus thuringiensis strain with activity against Locusta migratoria manilensis by PCR-based genome walking. The sequence of the cry gene was 3,432 bp long, and it encoded a Cry protein of 1,144 amino acid residues with a molecular mass of 129,196.5 kDa, which exhibited 62% homology with Cry7Ba1 in the amino acid sequence. The δ-endotoxin with five conserved sequence blocks in the amino-terminal region was designated Cry7Ca1 (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"EF486523","term_id":"1121787749","term_text":"EF486523"}}EF486523). Protein structure analysis suggested that the activated toxin of Cry7Ca1 has three domains: 227 residues forming 7 α-helices (domain I); 213 residues forming three antiparallel β-sheets (domain II); and 134 residues forming a β-sandwich (domain III). The three domains, respectively, exhibited 47, 44, and 34% sequence identity with corresponding domains of known Cry toxins. SDS-PAGE and Western blot analysis showed that Cry7Ca1, encoded by the full-length open reading frame of the cry gene, the activated toxin 1, which included three domains but without the N-terminal 54 amino acid residues and the C terminus, and the activated toxin 2, which included three domains and N-terminal 54 amino acid residues but without the C terminus, could be expressed in Escherichia coli. Bioassay results indicated that the expressed proteins of Cry7Ca1 and the activated toxins (toxins 1 and 2) showed significant activity against 2nd instar locusts, and after 7 days of infection, the estimated 50% lethal concentrations (LC₅₀s) were 8.98 μg/ml for the expressed Cry7Ca1, 0.87 μg/ml for the activated toxin 1, and 4.43 μg/ml for the activated toxin 2. The δ-endotoxin also induced histopathological changes in midgut epithelial cells of adult L. migratoria manilensis.     

Dependence of pathogen molecule-induced Toll-like receptor activation and cell function on Neu1 sialidase

The signaling pathways of mammalian Toll-like receptors (TLR) are well characterized, but the initial molecular mechanisms activated following ligand interactions with the receptors remain poorly defined. Here, we show a membrane controlling mechanism that is initiated by ligand binding to TLR-2, -3 and-4 to induce Neu1 sialidase activity within minutes in live primary bone marrow (BM) macrophage cells and macrophage and dendritic cell lines. Central to this process is that Neu1 and not Neu2,-3 and-4 forms a complex with TLR-2,-3 and-4 on the cell surface of naïve macrophage cells. Neuraminidase inhibitors BCX1827, 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA), zanamivir and oseltamivir carboxylate have a limited significant inhibition of the LPS-induced sialidase activity in live BMC-2 macrophage cells but Tamiflu (oseltamivir phosphate) completely blocks this activity. Tamiflu inhibits LPS-induced sialidase activity in live BMC-2 cells with an IC₅₀ of 1.2?μM compared to an IC₅₀ of 1015?μM for its hydrolytic metabolite oseltamivir carboxylate. Tamiflu blockage of LPS-induced Neu1 sialidase activity is not affected in BMC-2 cells pretreated with anticarboxylesterase agent clopidogrel. Endotoxin LPS binding to TLR4 induces Neu1 with subsequent activation of NFκB and the production of nitric oxide and pro-inflammatory IL-6 and TNFα cytokines in primary and macrophage cell lines. Hypomorphic cathepsin A mice with a secondary Neu1 deficiency respond poorly to LPS-induced pro-inflammatory cytokines compared to the wild-type or hypomorphic cathepsin A with normal Neu1 mice. Our findings establish an unprecedented mechanism for pathogen molecule-induced TLR activation and cell function, which is critically dependent on Neu1 sialidase activity associated with TLR ligand treated live primary macrophage cells and macrophage and dendritic cell lines.