拟南芥转录共激活子ANGUSTIFOLIA3(AN3)调控花的雄蕊的形成

雄蕊是种子植物产生花粉的重要生殖器官,其是否正常发育关乎到植物的繁殖状况,并且会对农作物的产量造成影响。通过RT-PCR技术鉴定拟南芥转录共激活子ANGUSTIFOLIA3（AN3）的两个敲除突变体an3-1和an3-4;通过形态学检测发现,突变体an3-1和突变体an3-4的雄蕊较野生型雄蕊短,而雌蕊却无明显变化;通过构建AN3启动子GUS表达载体,对Pro-AN3-GUS植株的花组织进行染色,并观察,结果表明,AN3基因在拟南芥的种子胚、成熟的花粉、柱头、花瓣中均有表达。这个结果证明AN3能在拟南芥生殖生长期间在花器官等重要组织中表达,这个结果与an3-1和an3-4的雄蕊变短的结论一致。由此,我们得出结论：拟南芥转录共激活子AN3正向调控花的雄蕊的形成。     

Isolation and characterization ofPleurotus ostreatus mutant strains resistant to a carboxin-derived fungicide,flutolanil

To develop a dominant genetic marker inPleurotus ostreatus, mutant strains resistant to a carboxin-derived fungicide, flutolanil, were isolated. These mutants included strains which showed resistance to 50-fold higher concentration of fluotolanil than the wild-type strain, even after successive cultivations in the absence of the drug. Dominance of the phenotype was confirmed by back-crossing between the resistant and wild-type monokaryons. The flutolanilresistance was also shown to be stably inherited by the basidiospore-derived progenies of the mutant strains.     

丙酮酸发酵能力的提高

筛选了 3 氟代丙酮酸敏感型突变株 ,丙酮酸发酵生产水平正突变率 1 0 0 % ,最高产酸达584mmol/L ,提高 77% ;作为对照 ,3 氟代丙酮酸抗性型的正突变率只有 1 2 .5%。第 2次γ 照射处理中 ,DG抗性突变株的残糖从 3 .2 1 g/L降至 0 .0 1 1 6g/L。     

Molecular Markers of Ph1 Gene in Chinese Spring and Development of Winter Wheat New Line Harboring ph1b Gene

he genomic DNA of common wheat (Triticum aestivum L.) “Chinese Spring” (CS) and its ph1b mutant were analyzed by using 19 sequence tagged site PCR (STS-PCR) primers, which derived from RFLP probes from barley (Hordeum vulgare L.) chromosome 5H. One marker was identified on wheat chromosome 5BL, which is 5.7 cM (centiMorgan) proximal to Ph1 gene, using the CS homoeologous group 5 nullisomic-tetrasomic, ditelosomic 5BL line and an F2 population from CS×ph1b mutant. This linked PCR marker was converted into a more specific sequence characterized amplified region (SCAR) marker. To obtain a new winter wheat line containing ph1b gene, the authors used a nullisomic 5B line of “Abbodanza”as a bridge parent and crossed respectively with the CS ph1b mutant (donor) and a winter wheat variety, “Jing 411” (recipient). The meiotic chromosome pairing was checked in the progeny of each cross, as well as using the marker-assistant selection of the SCAR marker identified for ph1b gene. After three inter-crossing and one selfing, a relatively stable ph1b substitution line of winter wheat with “Jing 411” background was obtained.     

Active site of deblocking aminopeptidase from Pyrococcus horikoshii.

New hyperthermostable aminopeptidase from the hyperthermophilic archaeon Pyrococcus horikoshii has acylamino acid releasing (deblocking) activity for acyl (blocked) peptides. Such an enzyme can be used for N-terminal sequencing of acyl peptides. To clarify the active site of the deblocking aminopeptidase, we prepared three mutants in which one of the three possible active site amino acid residues (Asp or Glu) was replaced with their amide derivatives. Activity and cobalt ion dependence of these mutants were examined and compared with those of the native enzyme. The results suggest that all the three possible residues (Asp173, Glu205, and Glu206) participate in the catalytic activity through binding with the cobalt ion.     

重组人可溶性B淋巴细胞刺激因子及其突变体的克隆、表达及活性测定

采用RT PCR方法从人外周血白细胞总RNA中钓取人可溶性B淋巴细胞刺激因子 (humansolubleBlym phocytestimulator,hsBLyS)的cDNA片段 ,再运用基因重组手段 ,利用通用型质粒pBV2 2 0构建表达载体pBV2 2 0 /hsBLyS。经测序鉴定后 ,以之为模板使用重叠PCR法扩增得到hsBLyS的两个点突变体hsBY A(Cys14 6→Ala14 6)和hsBY V (Cys14 6→Val14 6)的基因片段 ,构建表达载体 pBV2 2 0 /hsBY A及 pBV2 2 0 /hsBY V。经测序无误后 ,将上述 3种载体分别转化大肠杆菌DH5α并诱导重组蛋白质表达 ,薄层扫描结果显示 3种蛋白质在DH5α中表达量都在 2 0 %～ 30 %之间。再分别运用变性、凝胶过滤层析及复性等手段纯化目的蛋白质 ,最后通过B淋巴细胞增殖实验检测纯化产物促人B细胞增殖的活性。实验结果表明 ,3种重组蛋白质都能明显刺激人B细胞增殖 ;统计学检验显示 ,突变体rhsBY V较野生型rhsBLyS的促人B淋巴细胞增殖活性显著增强。     

The electron transport system of Alcaligenes eutrophus H16

In a previous work (Kömen et al. 1991) it has been concluded that membrane fragments isolated from autotrophically grown Alcaligenes eutrophus H16 contain several iron-sulphur centres along with haems of a-, b-, c-, and d-type. These redox components have been proposed to be part of a branched respiratory chain leading to multiple membrane bound oxidases. Here, some of the respiratory activities catalyzed by membrane fragments from wild type cells of A. eutrophus (H16) and, for comparison, Paracoccus denitrificans, have been investigated through the use of electron transport inhibitors. Cyanide (CN^-) titration curves indicated that in A. eutrophus H16 oxidation of succinate and H₂ preferentially proceeds via the cytochrome c oxidase(s) branch (I ₅₀=2 · 10^-5 M) whereas the NADH dependent respiration started being inhibited at higher CN^- concentrations (I ₅₀=5 · 10^-4 M). In membranes isolated from both, cells harvested at late growth-phase (OD 12) and from a mutant deficient in cytochrome c oxidase activity (A. eutrophus RK1), respiration was insensitive to low CN^- concentrations (< 10^-4 M), and it was sustained by the high catalytic activities of two quinol oxidases. These alternative oxidases of b- (formally o-) and d-type showed different sensitivities to KCN (I ₅₀=10^-3 M and 10^-2 M, respectively). Interestingly, the cytochrome c oxidase(s) dependent respiration of H16 membranes was insensitive to antimycin A but largely inhibited by myxothiazol (10^-6 M). This, and previous work (Kömen et al. 1991), suggest that although the respiratory chain of A. eutrophus is endowed with a putative bc ₁ complex, its biochemical nature and role in respiration of this organism are apparently different from those of P. denitrificans. The peculiarity of the respiratory chain of A. eutrophus is confirmed by the rotenone insensitivity of the NADH oxidation in both protoplasts and membrane fragments from wild type and soluble hydrogenase deficient cells (HF14 and HF160). A tentative model of the respiratory chain of autotrophically grown A. eutrophus is presented.