Genome- and species-specific markers and genome relationships of diploid perennial species in Triticeae based on RAPD analyses.

Eight different genomes (E, H, I, P, R, St, W, and Ns) represented by 22 diploid species of the tribe Triticeae were analyzed using the random amplified polymorphic DNA (RAPD) technique. The genome relationships were obtained based on 371 RAPD fragments produced with 30 primers. The four species of the genus Psathyrostachys (having various Ns genomes) were closely related. The genomes Ee and Eb had a similarly close relationship and were distinct from all other genomes analyzed. Genomes P, R, and St were grouped in one cluster and genomes H and I in another. Genome W had a distant relationship with all other genomes. These results agree with the conclusions from studies of chromosome pairing and isozyme and DNA sequence analyses. Twenty-nine and 11 RAPD fragments are considered to be genome- and species-specific markers, respectively. One to six genome-specific markers were identified for each genome. These RAPD markers are useful in studies of genome evolution, analysis of genome composition, and genome identification.     

催产素在脊髓水平对电针镇痛的影响

采用玻璃微电极胞外记录和脊髓表面给药的方法观察了催产素（ＯＴ）、抗催产素血清（ＡＯＴＳ）以及电针穴位对背角神经元伤害性诱发放电的影响。结果表明：电针穴位或脊髓表面施加ＯＴ可部分抑制脊髓背角神经元的伤害性诱发放电;在电针的基础上施加ＯＴ则明显加强电针的抑制效应;相反,用ＡＯＴＳ预处理后,电针的抑制作用放取消。提示ＯＴ在脊髓水平参与了对痛觉信息的调制,并与一定频率的针刺镇痛有关。     

Substrate selectivity of squalene synthetase.

Six 1-3H-labeled analogues of farnesyl pyrophosphate have been studied as potential substrates for yeast and rat liver squalene synthetases: 2-methylfarnesyl pyrophosphate (4), 3-demethylfarnesyl pyrophosphate (5), 7,11-dimethyl-3-ethyl-2,6,10-dodecatrienyl pyrophosphate (6), 6,7,10,11-tetrahydrofarnesyl pyrophosphate (7), 4-methylthiofarnesyl pyrophosphate (8), and 4-fluorofarnesyl pyrophosphate (9). Analogues 4 and 5 are enzymatically incorporated into 11-methylsqualene (10) and 10-demethylsqualene (11), respectively, even if no farnesyl pyrophosphate is added to the incubations. None of the other analogues gives nonpolar products with either the yeast or liver enzymes. No tritium is enzymatically released to the medium from any of the analogues, indicating that they are not accepted at the first (proton exchanging) site. The data rule out formation of dead-end presqualene pyrophosphate products with analogues as first, but not as second, substrates. Implications of these results for the enzyme active-site topology and mechanism are discussed.     

Production of antibody against T-2 toxin.

Antibody against T-2 toxin was obtained after immunization of rabbits with bovine serum albumin-T-2 hemisuccinate conjugate. The antibody had greatest binding efficiency for T-2 toxin, less efficiency for HT-2, and least for T-2 triol. Cross-reaction of antibody with neosolaniol, T-2 tetraol, and 8-acetyl-neosolaniol was very weak. Diacetoxyscirpenol, trichodermin, vomitoxin, and verrucarin A essentially gave no cross-reaction with the antibody. The sensitivity of the binding assay for T-2 toxin detection was in the range of 1 to 20 ng per assay. Detailed methods for the preparation of the conjugate and the production of immune serum and methods for antibody determination are described.     

The use of rotating disk voltammetry for the determination of homogeneous small molecule--redox protein reaction rates

Rotating disk voltammetry was used in this work to study the rates of reaction of ferricytochrome c with two very strong reductants, methyl and benzyl viologen. The rates of reaction for these reductants were found to be 4.0 × 10⁷ and 5.4 × 10⁷m^?1s^?1 at 24°C for benzyl and methyl viologen, respectively. The versatility of this method was demonstrated by the ease with which the activation parameters were obtained. The ΔH^≠ and ΔS^≠ were found to be 4.0 kcal/mol and ?10.6 cal/mol-K, respectively, for benzyl viologen. All the observed reaction rates were corrected for coulombic effects by the method of Wherland and Gray, and the electrostatically corrected rate constants were compared with the Marcus and Hopfield theories for electron transfer. The agreement was excellent for the tunneling theory but there were some discrepancies with the absolute Marcus theory. The relative Marcus approach worked quite well and, by taking into account the nonadiabaticity of the electron transfer, reasonable values were obtained for the absolute Marcus theory when realistic values of the self-exchange constants were used.     

Estimation of whole-plant resistance to gaseous exchange independent of leaf temperature measurement

For studies into the uptake of mercury vapor by wheat (Triticum aestivum), a simple theory and plant chamber were employed to estimate total leaf resistance of whole plants to water vapor exchange. The estimates were independent of leaf temperature, for which mean values were indirectly determined. The approach involved the measurement, at steady-state conditions, of the net change in water vapor flux per unit of leaf surface (Δq_v) in response to a small induced change in absolute humidity (ΔC_a). Assuming that total leaf resistance (r_l) was constant and that change in leaf temperature (T_l) was negligible, total leaf resistance was calculated from the equation, [Formula: see text]     

稀土元素Pr~(3+)、Nd~(3+)对蚕豆(Vicia feba)叶片原生质膜上Ca~(2+)·Mg~(2+)-ATPase活性的影响

本文介绍用二相分配法制备蚕豆叶片原生质膜上的Ca~(2+)·Mg~(2+)-ATPase,用以研究镧系,稀土离子对此酶活性的影响。初步证实Pr~(3+)、Nd~(3+)对依赖于CaM的以及不依赖于CaM的蚕豆叶片原生质膜上Ca~(2+)·Mg~(2+)-ATPase活性的抑制不是CaM专一的。     

Evidence forCis- andTrans-acting element coevolution of the 2-μm circle genome inSaccharomyces cerevisiae

Summary We compared the DNA sequence of the yeas 2-μm plasmidcis-actingSTB andtrans-actingREP1 partition loci of laboratory haploid and industrial amphiploid strains. Several industrial strains had a uniqueSTB sequence (type 1) sharing only 70% homology with laboratorySTB (type 2). Type 1 plasmids had a REP1 protein with 6–10% amino acid substitutions when compared to REP1 of type 2 plasmids. All 2-μm variants that shared a similarSTB consensus sequence exhibited a high degree ofREP1 nucleotide and amino acid sequence conservation. These observations suggest molecular coevolution oftrans-acting elements with cognate target DNA structure. Based on DNA sequencing and Southern hybridization analyses, we classified 2-μm variants into two main evolutionary lineages that differ atSTB as well asREP1 loci. The role of molecular coevolution in yeast intra- and interspecies plasmid evolution was discussed.     

Synthesis of [D-Ala2,4'-125I-Phe3,Glu4]deltorphin and characterization of its delta opioid receptor binding properties.

Both [D-Ala2,Glu4]Deltorphin and [D-Ala2,4'-I-Phe3,Glu4]Deltorphin are highly selective ligands for delta, relative to mu, opioid receptors. Radiolabeled [D-Ala2, 4'-125I-Phe3,Glu4]Deltorphin ([125I]Deltorphin) was prepared with a specific activity of 2200 Ci/mmol from [D-Ala2, 4'-NH2-Phe3, Glu4]Deltorphin through a diazonium salt intermediate. The inhibition of [125I]Deltorphin binding to rat brain membranes by ligands selective for mu, delta, and kappa opioid receptors is consistent with binding by the radioligand to a single site having the properties of a delta opioid receptor. The results of these studies are in good agreement with those obtained by structurally different delta opioid receptor ligands. The similarity between the delta receptor site labeled by [125I]Deltorphin and those labeled by other delta receptor agonists, in contrast to differences seen by in vivo studies of their analgesic effects, is discussed.