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111.
Nan Zhang Zhen Song Yuhua Xie Ping Cui Hongxia Jiang Tao Yang Ruicheng Ju Yuhua Zhao Jinyu Li Xunli Liu 《World journal of microbiology & biotechnology》2013,29(8):1443-1452
An antifungal Actinomyces BS-112 strain, with Aspergillus flavus as the target pathogen, was isolated from soil in the forest land of Mountain Tai. This strain showed a strong antagonistic activity against various mold fungi in food and feed. Strain BS-112 was identified as Streptomyces hygroscopicus based on its morphologic, cultural, physiological, biochemical characteristics, cell wall components and 16S rDNA sequence. Four active components were separated and purified from strain BS-112. These four antifungal components were identified as tetrins A and B and tetramycins A and B using spectroscopic analysis including mass spectrometry and nuclear magnetic resonance spectroscopy. Tetrins A and B and tetramycins A and B strongly inhibited the growth of A. flavus, A. alutaceus, A. niger, and A. fumigatus in vitro. 相似文献
112.
Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes. 相似文献
113.
114.
苏北滨海湿地麋鹿恢复种群的研究 总被引:1,自引:0,他引:1
1986年至2004年,在苏北滨海湿地开展恢复麋鹿野生种群的研究。从每年的2月份开始,在麋鹿的产仔期按照每旬记录产仔数,直至产仔结束。逐年统计半散养和野生麋鹿种群结构。选择不同年龄阶段和不同性别的麋鹿进行称重,分析个体的身体发育程度。半散养麋鹿种群由1986年引进的39 头,发展到2004年的706 头,年均出生率21.7%,鹿群年均增长率为17.5%,现已繁殖了子四代;野生放养麋鹿由31 头增加到2004年的41头,年均出生率16.3%,年均增长率为9.0% ,且于2003年、2004年各产1 头完全属野生的子二代。产仔季节相由引进时的紊乱已调整至目前的规律性产仔。研究表明大丰麋鹿种群繁殖很成功,其寿命、行为、生理发育、繁殖周期等都较引进时发生了显著的变化,已完全适应了黄海湿地生态环境。人类活动干扰仍是影响麋鹿种群恢复的一个重要因素。 相似文献
115.
应用RAPD技术对大熊猫分类地位的探讨 总被引:15,自引:3,他引:15
采用PCR和Southern杂交等方法对大熊猫与小熊猫、马来熊、浣熊等共有的一条1.3kb的RAPD产物片段进行了初步分析。研究结果显示,来自于大熊猫的此共有片段可能为一重复序列,并且其内部含有多个随机引物AB1-08的结合位点。以此来自于大熊猫的1.3kb片段为探针进行杂交,发现马来熊RAPD产物中的对应片段显示了很高的同源性,而小熊猫和浣熊RAPD产物则无相应的杂交带。这暗示,从分类地位上来看,大熊猫与熊科马来熊的亲缘关系应更近于与小熊猫和浣熊的亲缘关系,应与马来熊一样划分为熊科。本研究为大熊猫分类地位的确定提供了又一分子生物学证据 相似文献
116.
生精细胞凋亡相关基因 总被引:2,自引:0,他引:2
细胞凋亡(apoptosis)是一种基因控制的细胞生理性自杀行为,用以维持细胞数量的相对恒定,可由某种刺激或抑制剂的移除而激活。在哺乳动物精子发生过程中,各级生精细胞都会发生相应的凋亡,通过严格调控以确保成熟精子生成的数量和质量。生精细胞的凋亡是一个许多基因参与的复杂的不可逆过程,其中Bcl-2/Bax基因族、p53基因、Fas-Fasl基因、C-myc基因、CREM基因、HSP基因族、c-Kit/SCF基因、Insl3基因、iNOS基因、BMP8B基因、TR基因和存活蛋白(survivin)基因等发挥了重要作用。研究哺乳动物睾丸生精细胞凋亡相关基因,有利于了解生精细胞凋亡机制,为进一步阐明精子发生的调控机制,预防和治疗精子发生相关疾病提供重要的理论依据。 相似文献
117.
Metabolic signalling and carbon partitioning: role of Snf1-related (SnRK1) protein kinase 总被引:15,自引:0,他引:15
Halford NG Hey S Jhurreea D Laurie S McKibbin RS Paul M Zhang Y 《Journal of experimental botany》2003,54(382):467-475
A protein kinase that plays a key role in the global control of plant carbon metabolism is SnRK1 (sucrose non-fermenting-1-related protein kinase 1), so-called because of its homology and functional similarity with sucrose non-fermenting 1 (SNF1) of yeast. This article reviews studies on the characterization of SnRK1 gene families, SnRK1 regulation and function, interacting proteins, and the effects of manipulating SnRK1 activity on carbon metabolism and development. 相似文献
118.
超声检测左心室舒张功能的临床意义——85例超声检测结果与冠状动脉造影的对照分析 总被引:2,自引:0,他引:2
目的超声心动图检测左心室舒张功能与冠状动脉造影对照分析,探讨超声诊断的临床意义。方法85例临床疑诊冠心病超声检查左心室二尖瓣口舒张早、晚期血流充盈速度E、A两峰峰值,计算E/A比值,其结果分为舒张功能正常和降低两组。全部病人均与冠状动脉造影结果对照分析。结果超声检测左心室舒张功能与冠脉造影均正常24例,均异常53例,共77例,符合率90.59%,不符合8例,占9.41%;本文依据冠脉造影提出超声检测左心室舒张功能正常值;并发现冠心病早期舒张功能降低,且随年龄与病程长短不同。结论超声检测左心室舒张功能的改变与冠脉造影符合率高,舒张功能于冠心病早期可降低,随病程长短不同,为临床对冠心病诊治和预防提供有价值的信息。 相似文献
119.
MOTIVATION: Protein-protein docking algorithms typically generate large numbers of possible complex structures with only a few of them resembling the native structure. Recently (Duan et al., Protein Sci, 14:316-218, 2005), it was observed that the surface density of conserved residue positions is high at the interface regions of interacting protein surfaces, except for antibody-antigen complexes, where a lesser number of conserved positions than average is observed at the interface regions. Using this observation, we identified putative interacting regions on the surface of interacting partners and significantly improved docking results by assigning top ranks to near-native complex structures. In this paper, we combine the residue conservation information with a widely used shape complementarity algorithm to generate candidate complex structures with a higher percentage of near-native structures (hits). What is new in this work is that the conservation information is used early in the generation stage and not only in the ranking stage of the docking algorithm. This results in a significantly larger number of generated hits and an improved predictive ability in identifying the native structure of protein-protein complexes. RESULTS: We report on results from 48 well-characterized protein complexes, which have enough residue conservation information from the same 59 benchmark complexes used in our previous work. We compute conservation indices of residue positions on the surfaces of interacting proteins using available homologous sequences from UNIPROT and calculate the solvent accessible surface area. We combine this information with shape-complementarity scores to generate candidate protein-protein complex structures. When compared with pure shape-complementarity algorithms, performed by FTDock, our method results in significantly more hits, with the improvement being over 100% in many instances. We demonstrate that residue conservation information is useful not only in refinement and scoring of docking solutions, but also helpful in enrichment of near-native-structures during the generation of candidate geometries of complex structures. 相似文献
120.