Chloroplast phosphoribulokinase associates with yeast phosphoriboisomerase in the presence of substrate

Pea chloroplastic phosphoribulokinase and yeast phosphoriboisomerase partition independently of one another in a two-phase polyethyleneglycol, dextran system, but apparent interaction is seen when ribose-5-phosphate is added to the two-phase system. It appears that the pea leaf of kinase recognizes yeast isomerase when it is carrying metabolite.     

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.     

Photocleavage of myosin subfragment 1 by vanadate

The heavy chain of myosin's subfragment 1 (S1) was cleaved at two distinct sites (termed V1 and V2) after irradiation with UV light in the presence of millimolar concentrations of vanadate and in the absence of nucleotides or divalent metals. The V1 site cleavage appeared to be identical with the previously described active site cleavage at serine-180, which is effected by irradiation of a photomodified form of the S1-MgADP-Vi complex [Cremo, C. R., Grammer, J. C., & Yount, R. G. (1989) J. Biol. Chem. 264, 6608-6011]. The V2 site was cleaved specifically, without cleavage at the V1 site, first by formation of the light-stable S1-Co2+ADP-Vi complex at the active site [Grammer, J. C., Cremo, C. R., & Yount, R. G. (1988) Biochemistry 27, 8408-8415] and then by irradiation in the presence of millimolar vanadate. By gel electrophoresis, the V2 site was localized to a region about 20 kDa from the COOH terminus of the S1 heavy chain. From the results of tryptic digestion experiments, the COOH-terminal V2 cleavage peptide appeared to contain lysine-636 in the linker region between the 50- and 20-kDa tryptic peptides of the heavy chain. This site appeared to be the same site cleaved by irradiation of S1 (not complexed with Co2+ADP-Vi) in the presence of millimolar vanadate as previously described [Mocz, G. (1989) Eur. J. Biochem. 179, 373-378]. Cleavage at the V2 site was inhibited by Co2+ but was not significantly affected by the presence of nucleotides or Mg2+ ions. Tris buffer significantly inhibited V2 cleavage. From the results of UV-visible absorption, 51V NMR, and frozen-solution EPR spectral experiments, it was concluded that irradiation with UV light reduced vanadate +5 to the +4 oxidation state, which was then protected from rapid reoxidation by O2 by complexation with the Tris buffer. The relatively stable reduced form or forms of vanadium were not competent to cleave S1 at either the V1 or the V2 site. 51V NMR titration experiments indicated that a tetrameric species of vanadium preferentially bound to S1 and to the S1-MgADP-Vi complex, whereas no binding of either the monomeric or dimeric species could be detected. These results suggest that the vanadate tetramer was responsible for the photocleavage of S1 which occurred at both the V1 and V2 sites in the absence of nucleotides or divalent metals.     

Etude comparee des proprietes physico-chimiques des mannanes de neuf levures

In order to correlate and compare the antigenic relationships observed between nine yeast strains, we have studied their major antigenic determinant represented by the mannans. This material is a constituent of their cell.The compounds that we have isolated are, in reality, glycopeptides. All their polysaccharide fractions consist of mannose only — except for those of the compounds that we have isolated of R. glutinis and C. lipolytica. All these polysaccharides have very close ramified structures; the only one that seems to be very different is that of R. glutinis, and this is in agreement with the antigenic properties of that yeast.The peptidic fractions of these glycopeptides are rich in threonine, serine and aspartic acid and it is very likely that these amino acids make the link with the polysaccharide fraction. The quantity of these amino acids seem to be affected by the conditions of culture of the yeasts, but not their presence or absence.     

The genetics of cell-mediated lympholysis.

The role of HLA antigens in the generation of cytotoxic cells in CML has been investigated. Cytotoxic effector cells were generated in MLC among HLA-A or HLA-A and HLA-B disparate, HLA-D identical siblings, and among HLA-A and HLA-B disparate, MLC identical (%RR less than or equal to 2 3.6) unrelated individual. The data indicate that HLA-D differences and poliferative MLC responses as measured by 3H-thymidine incorporation are not requisite for the in vitro generation of cytotoxic cells and suggest the existence of a CML-S locus (loci) distinct from HLA-A, HLA-B and HLA-D. The degree of cytotoxicity generated in a proliferative versus a "nonproliferative" MLC was comparable. In addition, these studies demonstrate that antigens other than the currently definable HLA-A, HLA-B, HLA-C, and HLA-D can serve as target determinants in cell-mediated lympholysis.     

苹果柠檬酸合酶3基因家族成员鉴定及表达分析

柠檬酸合酶(citrate synthase 3, CS3)是细胞代谢途径中的关键酶之一,其活性调节着生物体的物质和能量代谢过程。本研究旨在从苹果全基因组中鉴定CS3基因家族成员,并进行生物信息学和表达模式分析,为研究苹果CS3基因的潜在功能提供理论基础。利用BLASTp基于GDR数据库鉴定苹果CS3家族成员,通过Pfam、SMART、MEGA5.0、clustalx.exe、ExPASy Proteomics Server、MEGAX、SOPMA、MEME和WoLF PSORT等软件分析CS3蛋白序列基本信息、亚细胞定位情况、结构域组成、系统进化关系以及染色体定位情况。利用酸含量的测定和实时荧光定量PCR (real-time fluorescence quantitative polymerase chain reaction, qRT-PCR)技术检测苹果6个CS3的组织表达和诱导表达特性。苹果CS3基因家族包含6个成员,这些CS3蛋白包括473−608个不等的氨基酸残基,等电点分布在7.21−8.82。亚细胞定位结果显示CS3蛋白分别定位在线粒体和叶绿体。系统进化分析可将其分为3类,各亚家族基因数量分别为2个。染色体定位结果显示,CS3基因分布在苹果不同的染色体上。蛋白二级结构以a-螺旋为主,其次是无规则卷曲,b-转角所占比例最小。筛选的6个家族成员在不同苹果组织中均有表达,整体表达趋势从高到低依次为MdCS3.4相对表达含量最高,MdCS3.6次之,其他家族成员相对表达量依次为MdCS3.3>MdCS3.2>MdCS3.1>MdCS3.5。qRT-PCR结果显示,MdCS3.1和MdCS3.3基因在酸含量较低的‘成纪1号’果肉中相对表达量最高,酸含量较高的‘艾斯达’果肉中MdCS3.2和MdCS3.3基因相对表达量最高。因此,本研究对不同苹果品种中CS3基因相对表达量进行了检测,并分析了其在苹果果实酸合成过程中的作用。结果表明,CS3基因在不同苹果品种中的相对表达量存在差异,为后续研究苹果品质形成机制提供了参考。