小麦辐射二代性状的数量遗传分析

本文采用生物统计和数量遗传学方法、分析了辐照剂量为0（对照）、15、25、35KR的铯─137γ射线对二个小麦品种的诱变效应及其选择效果;估算了七个数量性状的分布特征数和遗传方差、遗传变异系数、遗传力、遗传进度、相对遗传进度等遗传参数。辐射二代的变异较大,有大粒、大穗、早熟突变体出现;株粒重、穗粒重、穗长、穗粒数、抽穗期的遗传变异系数和相对遗传进度都较大,选择效果较好;铯-137γ射线能有效地应用于小麦辐射育种,且适宜辐照剂量为35KR。     

冰核细菌及冰核基因的应用研究进展

引起水由液态变为固态的物质称为冰核或成核剂。冰核种类繁多,目前已发现4属23种或变种的细菌、4属11种或变种的真菌和1种病毒,它们都具成冰活性。细菌冰核是一类蛋白质,也称冰蛋白,由细菌冰核基因编码。作为生物冰核领域的研究重点,冰核细菌的研究已涉及到促冻杀虫、防霜冻、植物病害等多个领域;同时冰核细菌已成功地应用于人工降雪、制冷和高敏检测等方面,具有广阔的应用前景。主要对冰核细菌的应用研究现状和发展进行综述。     

Detection of Phytophthora nicotianae in Soil with Real-time Quantitative PCR

Phytophthora nicotianae is one of the most important soil-borne plant pathogens. A rapid, specific and sensitive real-time polymerase chain reaction (PCR) detection method for P. nicotianae was established, which used primers targeting the internal transcribed spacer (ITS) regions of rDNA genes of Phytophthora spp. Based on the nucleotide sequences of ITS2 of 15 different species of Phytophthora , the primers and probe were designed specifically to amplify DNA from P. nicotianae. With a series of 10-fold DNA dilutions extracted from P. nicotianae pure cultures, the detection limit was 10 pg/μl in conventional PCR, whereas in SYBR Green I PCR the detection limit was 0.12 fg/μl and in TaqMan PCR 1.2 fg/μl, and real-time PCR was 10⁴–10⁵ times more sensitive than conventional PCR. The simple and rapid procedures maximized the yield and quality of recovered DNA from soil and allowed the processing of many samples in a short time. The direct DNA extractions from soil were utilized to yield DNA suitable for PCR. By combining this protocol with the real-time PCR procedure it has been possible to specifically detect P. nicotianae in soil, and the degree of sensitivity was 1.0 pg/μl. The system was applied to survey soil samples from tobacco field sites in China for the presence of P. nicotianae and the analyses of naturally infested soil showed the reliability of the real-time PCR method.     

Molecular characterization and functional analysis by heterologous expression in E. coli under diverse abiotic stresses for OsLEA5, the atypical hydrophobic LEA protein from Oryza sativa L

In this study, we report the molecular characterization and functional analysis of OsLEA5 gene, which belongs to the atypical late embryogenesis abundant (LEA) group 5C from Oryza sativa L. The cDNA of OsLEA5 contains a 456 bp ORF encoding a polypeptide of 151 amino acids with a calculated molecular mass of 16.5 kDa and a theoretical pI of 5.07. The OsLEA5 polypeptide is rich in Leu (10%), Ser (8.6%), and Asp (8.6%), while Cys, Trp, and Gln residue contents are very low, which are 2, 1.3, and 1.3%, respectively. Bioinformatic analysis revealed that group 5C LEA protein subfamily contains a Pfam:LEA_2 domain architecture and is highly hydrophobic, intrinsically ordered with largely β-sheet and specific amino acid composition and distribution. Real-time PCR analysis showed that OsLEA5 was expressed in different tissue organs during different development stages of rice. The expression levels of OsLEA5 in the roots and panicles of full ripe stage were dramatically increased. The results of stress tolerance and cell viability assay demonstrated that recombinant E. coli cells producing OsLEA5 fusion protein exhibited improved resistance against diverse abiotic stresses: high salinity, osmotic, freezing, heat, and UV radiation. The OsLEA5 protein confers stabilization of the LDH under different abiotic stresses, such as heating, freeze–thawing, and drying in vitro. The combined results indicated that OsLEA5 protein was a hydrophobic atypical LEA and closely associated with resistance to multiple abiotic stresses. This research offered the valuable information for the development of crops with enhanced resistance to diverse stresses.     

拟南芥转录因子NF-YC的原核表达及多克隆抗体制备

采用PCR方法扩增NF-YC基因得到其全长cDNA序列,并将其克隆至原核表达载体pET-48b中,在大肠杆菌BL21中用IPTG诱导出分子量约为45 kD的融合蛋白,SDS-PAGE和Western blotting检测鉴定表达产物。利用亲和层析技术对融合蛋白进行纯化,纯化后的目的蛋白免疫新西兰兔制备多克隆抗体。间接ELISA检测抗体效价大于1 62 500,Western blotting结果显示,该抗体可特异性识别NF-YC蛋白。     

小麦eIF3c基因片段的克隆及序列分析

根据真核翻译起始因子eIF3c的保守序列,搜索小麦EST,由拼接的序列设计引物,从普通小麦‘川麦107'幼苗总RNA中克隆出1102bp的小麦eIF3c1基因片段命名为WeIF3c1.序列分析表明,该片段推断的氨基酸序列与两个拟南芥、水稻、甜樱桃、人类、线虫、老鼠等物种的真核翻译起始因子eIF3c相比较同源性分别为69、61%、85%、72%、38%、36%和38%.     

Cardiac restricted overexpression of kinase-dead mammalian target of rapamycin (mTOR) mutant impairs the mTOR-mediated signaling and cardiac function

Mammalian target of rapamycin (mTOR) is a key regulator for cell growth through modulating components of the translation machinery. Previously, numerous pharmacological studies using rapamycin suggested that mTOR has an important role in regulating cardiac hypertrophic growth. To further investigate this assumption, we have generated two lines of cardiac specific mTOR transgenic mice, kinase-dead (kd) mTOR and constitutively active (ca) mTOR, using alpha-myosin heavy chain promoter. alpha-Myosin heavy chain (alphaMHC)-mTORkd mice had a near complete inhibition of p70 S6k and 4E-BP1 phosphorylation, whereas alphaMHC-mTORca had a significant increase in p70 S6k and 4E-BP1 phosphorylation. Although the cardiac function of alphaMHC-mTORkd mice was significantly altered, the cardiac morphology of these transgenic mice was normal. The cardiac hypertrophic growth in response to physiological and pathological stimuli was not different in alphaMHC-mTORkd and alphaMHC-mTORca transgenic mice when compared with that of nontransgenic littermates. These findings suggest that the mTOR-mediated signaling pathway is not essential to cardiac hypertrophic growth but is involved in regulating cardiac function. Additional analysis of cardiac responses to fasting-refeeding or acute insulin administration indicated that alphaMHC-mTORkd mice had a largely impaired physiological response to nutrient energy supply and insulin stimulation.     

Cloning, sequencing and expression of the xylanase gene from a Bacillus subtilis strain B10 in Escherichia coli

Bacillus subtilis strain B10 was isolated for degumming of ramie blast fibers, and a fragment of 642-bp was amplified from chromosomal DNA by using primers directed against the sequence of Bacillus subtilis xylanase gene given in GenBank. The positive clones were screened on the selected LB agar plates supplemented with xylan by Congo-red staining method. The recombinant plasmid from one positive clone was used for further analysis and DNA sequencing. The gene sequence is different from the reported xylanase gene sequence in sites of two base pairs. The recombinant plasmid was expressed in Escherichia coli, and xylanase activity was measured. The xylanase distribution in extracellular, intracellular and periplasmic fractions were about 22.4%, 28.0% and 49.6%, respectively. The xylanase had optimal activity at pH 6.0 and 50 degrees C.