Essential role of Fkbp6 in male fertility and homologous chromosome pairing in meiosis

Meiosis is a critical stage of gametogenesis in which alignment and synapsis of chromosomal pairs occur, allowing for the recombination of maternal and paternal genomes. Here we show that FK506 binding protein (Fkbp6) localizes to meiotic chromosome cores and regions of homologous chromosome synapsis. Targeted inactivation of Fkbp6 in mice results in aspermic males and the absence of normal pachytene spermatocytes. Moreover, we identified the deletion of Fkbp6 exon 8 as the causative mutation in spontaneously male sterile as/as mutant rats. Loss of Fkbp6 results in abnormal pairing and misalignments between homologous chromosomes, nonhomologous partner switches, and autosynapsis of X chromosome cores in meiotic spermatocytes. Fertility and meiosis are normal in Fkbp6 mutant females. Thus, Fkbp6 is a component of the synaptonemal complex essential for sex-specific fertility and for the fidelity of homologous chromosome pairing in meiosis.     

Characterization of ethylene biosynthesis and its regulation during fruit ripening in kiwifruit,Actinidia chinensis ‘Sanuki Gold’

Ethylene biosynthesis in kiwifruit, Actinidia chinensis ‘Sanuki Gold’ was characterized using propylene, an ethylene analog, and 1-methylcyclopropene (1-MCP), an inhibitor of ethylene perception. In fruit harvested between a young stage (66 days after pollination) (DAP) and an early commercial harvesting stage (143 DAP), 2 days of exposure to propylene were sufficient to initiate ethylene biosynthesis while in fruit harvested at commercial harvesting stage (154 DAP), 4 days of propylene treatment were required. This observation suggests that response of ethylene biosynthesis to propylene treatment in kiwifruit declined with fruit maturity. Propylene treatment resulted in up-regulated expression of AC-ACO1, AC-ACO2, AC-SAM1 and AC-SAM2, prior to the induction of AC-ACS1 and ethylene production, confirming that AC-ACS1 is the rate limiting step in ethylene biosynthesis in kiwifruit. Treatment of fruit with more than 5 μL L^?1 of 1-MCP after the induction of ethylene production subsequently suppressed ethylene production and expression of ethylene biosynthesis genes. Treatment of fruit with 1-MCP at harvest followed with propylene treatment delayed the induction of ethylene production and AC-ACS1 expression for 5 days. These observations suggest that in ripening kiwifruit, ethylene biosynthesis is regulated by positive feedback mechanism and that 1-MCP treatment at harvest effectively delays ethylene production by 5 days.     

拟南芥未知基因At018融合蛋白原核表达条件的优化及纯化

本课题组在前期的研究中利用Al Cl3胁迫筛选碱茅全长c DNAs酵母表达文库获得到一个与铝毒害相关的未知基因(基因编号为018,用put018表示),该基因与拟南芥中未知基因(基因号为At5g57345,本研究中用At018表示)有较高的同源性。为了获得At018的纯化蛋白,本研究将拟南芥At018基因克隆后构建原核表达载体p GEX-6p-3-At018,再将其转入大肠杆菌BL21(DE3)菌株,利用异丙基-β-D-硫代半乳糖苷(IPTG)进行诱导表达。同时运用传统方法优化诱导条件,以提高重组融合蛋白的表达效率。SDS-PAGE分析结果表明,30℃下0.1 mmol/L IPTG的条件下诱导3 h后,GST-At018融合蛋白的表达量最大,蛋白分子质量与预测值相符,该蛋白主要以可溶性形式存在;接着利用Glutathione Sepharose4 Fast Flow亲核层析树脂纯化最终获得GST-At018融合蛋白。本研究可为进一步进行At018的功能解析提供基础。     

Detection of Mycoplasma hyopneumoniae in lung and nasal swab samples from pigs by nested PCR and culture methods

We examined nasal swab and lung homogenate samples collected from pigs experimentally and naturally infected with Mycoplasma hyopneumoniae for the detection of M. hyopneumoniae by the nested PCR (nPCR) and culture methods. In the 23 experimentally infected pigs, M. hyopneumoniae was commonly detected in nasal swabs by the nPCR and culture methods at 4 weeks after inoculation, and there was a significant correlation (P<0.01) between the titers of viable organisms in nasal swabs and in lung homogenates in the experimentally inoculated pigs. In the naturally infected pigs, on the other hand, discrepancies in detection were found between nasal swab and lung homogenate samples in 17 of 36 cases, although the presence of gross lung lesions correlated relatively well with the detection of organisms from the samples. Our results indicated that the diagnosis of mycoplasmal pneumonia by nPCR in individual pigs with nasal swabs is reliable under these experimental conditions. At present, nPCR with nasal swabs should only be used for monitoring the disease status at the herd level under field conditions.     

A plant vacuolar protease, VPE, mediates virus-induced hypersensitive cell death

Programmed cell death (PCD) in animals depends on caspase protease activity. Plants also exhibit PCD, for example as a response to pathogens, although a plant caspase remains elusive. Here we show that vacuolar processing enzyme (VPE) is a protease essential for a virus-induced hypersensitive response that involves PCD. VPE deficiency prevented virus-induced hypersensitive cell death in tobacco plants. VPE is structurally unrelated to caspases, although VPE has a caspase-1 activity. Thus, plants have evolved a regulated cellular suicide strategy that, unlike PCD of animals, is mediated by VPE and the cellular vacuole.     

Improving the antibacterial activity against Staphylococcus aureus of composite sheets containing wasted tea leaves by roasting

We used various kinds of wasted tea leaves to develop composite sheets with antibacterial properties. Antibacterial tests showed that the number of viable bacterial cells for the sheet containing wasted green tea leaves was around 10:⁶–10⁷ CFU/ml after 18 h culture compared to 108 CFU/ml for a tea-free sheet. This indicates that cell growth was signifi cantly inhibited. For sheets containing other types of tea leaves (oolong, black, hojicha, and pu-erh), living cells were not found, indicating that these sheets had superior antibacterial effects. Living cells were also not found in sheets containing wasted black tea leaves or roasted tea leaves at a concentration of 60% by weight after 6 h cultivation. Therefore, roasting treatment of wasted green tea leaves was examined to improve the antibacterial activity of the sheet. In particular, the focus was on structural conversion of catechins by heating.     

Stabilization of labile carbonyl addition intermediates by a synthetic receptor

Products of unfavorable chemical equilibria are not readily observed because their high energy and increased reactivity result in low concentrations. Biological macromolecules use binding forces to access unfavorable equilibria and stabilize reactive intermediates by isolating them from the medium. In a similar vein, we describe here a synthetic receptor that allows direct observation of labile tetrahedral intermediates: hemiaminals formed in the reaction of an aldehyde carbonyl group with amines. The receptor encapsulates alkyl-substituted primary amines, then orients them toward a covalently tethered aldehyde function. The hemiaminal intermediates appear at high concentration, confined from the bulk solution and observable at ambient temperature by conventional nuclear magnetic resonance spectroscopy.