Comparative analysis of multiple protein-sequence alignment methods [published erratum appears in Mol Biol Evol 1994 Sep;11(5):811]

We have analyzed a total of 12 different global and local multiple protein-sequence alignment methods. The purpose of this study is to evaluate each method's ability to correctly identify the ordered series of motifs found among all members of a given protein family. Four phylogenetically distributed sets of sequences from the hemoglobin, kinase, aspartic acid protease, and ribonuclease H protein families were used to test the methods. The performance of all 12 methods was affected by (1) the number of sequences in the test sets, (2) the degree of similarity among the sequences, and (3) the number of indels required to produce a multiple alignment. Global methods generally performed better than local methods in the detection of motif patterns.      

鸡马立克氏病病毒B抗原片段在大肠杆菌中表达

鸡马立克氏病病毒ＢａｍＨＩ基因文库Ｉ３质粒中含有编码Ｂ抗原膜外Ｄｏｍａｉｎ的ＤＮＡ序列。经ＳｃａＩ和ＳｐｈＩ双酶酶解Ｉ３质粒,分离获得７６４ｂｐＤＮＡ片段,并克隆进Ｍ１３ｍｐ１９中。ＤＮＡ序列测定分析表明克隆片段为ＭＤＶ－Ｂ抗原基因的４９４－１２５８ｂｐ部分序列。进一步分离ＮｃｏＩ－ＨｉｎｄＩＩＩ部分基因片（５３０ｂｐ）,克隆于ＰＬＰｒｏｍｏｔｅｒ控制下的含有修饰型ｃＩｔｓ８５７基因的表达载体中,     

嗜盐耐盐微生物抗盐胁迫相关离子转运蛋白研究进展

离子转运蛋白在维持细胞内pH稳态、离子动态平衡等方面发挥着重要作用。钠离子转运体和钾离子转运体在嗜盐耐盐微生物中广泛存在,其"保钾排钠"机制是微生物抗盐胁迫的两大策略之一。近年来,嗜盐耐盐微生物中许多新型钠、钾离子转运体被陆续发现,如RDD蛋白、UPF0118蛋白、DUF蛋白和KimA蛋白等;Fe³⁺、Mg²⁺等其他金属离子的转运蛋白也被证实可通过影响微生物胞内相容性溶质的合成起到渗透调节的作用。本文综述了嗜盐耐盐微生物中抗盐胁迫相关的各类离子转运蛋白,分析其分子结构和工作机理,并对这些蛋白在农业方面的应用进行了展望。继续发现新的离子转运蛋白,探究抗盐胁迫相关离子转运蛋白的结构和机理,解析各转运系统的协同作用及分子调控机制,将进一步加深对嗜盐耐盐微生物抗盐胁迫调控的认识,并为盐碱地农作物的改良等提供新的思路。     

Electrically induced calcium elevation,activation, and parthenogenetic development of bovine oocytes

The influence of electrical stimulation on the level of intracellular Ca²⁺ in bovine oocytes, as well as activation and extent of parthenogenetic development, was investigated. Mature oocytes were electrically stimulated at 29 hr of maturation, and intracellular Ca²⁺ concentration was determined with the Ca²⁺ indicator fura-2 dextran (fura-2 D). The Ca²⁺ response of oocytes to a given electrical pulse was variable. Oocytes responded with either no Ca²⁺ rise from baseline (≈? 12 nM), a short-duration Ca²⁺ rise (from 12 nM to 300 nM) that returned to baseline within 2 min of the pulse, or a long-duration Ca²⁺ rise (from 12 nM to 1,000–2,000 nM) that never returned to baseline during the 8 min period over which the oocytes were monitored. In these oocytes, Ca²⁺ level returned to baseline when oocytes were removed from 0.30 M mannitol and placed in an ionic medium. Increasing field strength or pulse duration tended to increase the proportion of oocytes displaying a Ca²⁺ rise, and at 1.0 kVcm^?1 for 40 μsec, all oocytes displayed a long-duration Ca²⁺ elevation. Direct transfer of oocytes from culture medium to mannitol also triggered a Ca²⁺ rise. Multiple stimulations, either electrical or by transferring to mannitol, produced multiple Ca²⁺ rises. This mannitol-induced Ca²⁺ rise could be inhibited by first washing the oocytes in medium containing equal parts of 0.30 M mannitol and phosphate buffered saline (PBS). The level of Ca²⁺ stimulation affected activation and development of oocytes. Insufficient, or, conversely, excessive Ca²⁺ stimulation impaired development. Optimum development was obtained with (1) three pulses of 0.2 kVcm^?1 for 20 μsec, each pulse 22 min apart, after direct transfer of oocytes from culture medium to mannitol (22% blastocysts) or (2) three pulses of 1.0 kVcm^?1 for 20 μsec after transfer of oocytes from culture medium to medium containing equal parts mannitol and PBS, then to mannitol (24% blastocysts). This procedure avoided induction of a Ca²⁺ rise prior to the pulse. The results indicate that the level of Ca²⁺ stimulation can be regulated by incubation conditions prior to the pulse and, to some extent, by field strength and pulse duration. The level of electrical stimulation influenced oocyte Ca²⁺ response, activation, and parthenogenetic development. © 1993 Wiley-Liss, Inc.     

柬埔寨白蝶兰，中国兰科一新记录种

报道中国兰科白蝶兰属一新记录种——柬埔寨白蝶兰Pecteilis cambodiana (Gagnep.) Aver.,描述其特征并提供了彩色图片。凭证标本保存于福建农林大学林学院树木标本室(FJFC)。     

厌氧氨氧化菌驱动脱氮途径的研究进展

厌氧氨氧化菌(anaerobic ammonia-oxidizing bacteria, AnAOB)的代谢多样性,使得该菌群能够在海洋、湿地和陆地等不同的自然生态系统中广泛分布,甚至在一些极热和极寒环境中也检测到了该菌群的存在。本文回顾并总结了厌氧氨氧化菌在不同生态系统中的发现、分布及脱氮贡献等方面的研究,分析了厌氧氨氧化菌分布的主要环境影响因素。该综述将帮助我们更好地理解全球氮循环中厌氧氨氧化菌的实际角色和功能,并基于厌氧氨氧化(anaerobicammoniaoxidation,anammox)过程,探究能与其进行协作的新型生物脱氮工艺,以期为这些工艺的研发和推广提供生态学基础和新的思考,从而实现脱氮工艺的技术变革。     

一株耐盐碱乳酪短杆菌G20响应盐碱胁迫的差异代谢物分析

【目的】探究耐盐碱乳酪短杆菌G20响应盐碱胁迫的代谢物组成以及代谢物合成潜力,为潜在功能分子和盐碱诱导的快速稳定响应逻辑门基因线路的挖掘提供参考。【方法】利用液相色谱-质谱联用技术(LC-MS)检测乳酪短杆菌G20盐碱环境与正常环境下4个生长时期的代谢产物。着重对富含高差异变化倍数代谢物的适应期与指数期进行分析。【结果】乳酪短杆菌G20可以在pH 10.0、9%NaCl环境中正常生长,同时环境pH值会随菌株生长逐步下降。综合正负离子2种模式,乳酪短杆菌G20在盐碱环境下各生长时期间差异代谢物数量分别为正常环境的0.69、0.75和0.81倍。盐碱胁迫诱导下适应期与指数期差异代谢物主要为苯环型化合物、有机酸及其衍生物与有机杂环类化合物。其中上调的有机酸化合物吲哚-3-乙酸、犬尿酸和葡萄糖酸指数期质谱信号强度低于适应期。菌株中可能存在的渗透保护剂有L-瓜氨酸、L-脯氨酸、N-乙酰鸟氨酸和左旋肉碱等。适应期变化倍数较大或质谱信号强度较高的差异化合物有毛果芸香碱、植物鞘氨醇和柠檬酸等,指数期有组胺、L-脯氨酸和硫胺素等。菌株差异代谢通路集中在氨基酸代谢与碳水化合物代谢。菌株代谢物中存在甜菜碱和...     

内生真菌印度梨形孢诱导小麦抗根腐病作用研究

【目的】明确印度梨形孢(Piriformospora indica)诱导小麦对根腐病产生抗性的作用机制。【方法】用印度梨形孢悬液浸种,以无菌培养液为对照,用病原菌禾谷镰孢菌(Fusarium graminearum)侵染小麦,对其相关生理生化指标及转录组变化进行分析。【结果】禾谷镰孢菌能诱导小麦产生过氧化氢,降低细胞内水含量,破坏细胞膜的稳定性;根部定殖印度梨形孢的小麦细胞内抗氧化酶活性增强,活性氧自由基含量降低,胞内水含量提高,细胞膜稳定性增强;印度梨形孢定殖能改变由于病原菌引起的mRNA转录组变化,抗性相关基因的表达增强。综合表明印度梨形孢定殖能有效地提高小麦对禾谷镰孢菌的抗性。【结论】研究结果为深入理解植物与微生物互作、开发新型高效环保抗根腐病生物制剂提供理论和实验依据。     

晋西黄土区土地利用对降雨入渗产流模式和优先流分布的影响试验研究

黄土高原退耕还林(草)工程显著改变了河川径流过程,但其作用机制尚不明晰。选取晋西黄土区4种典型下垫面(20年和30年刺槐人工林地、草地、休耕地)分别开展连续3场模拟降雨试验,观测坡面入渗产流过程,并结合染色示踪和图像处理软件技术,分析土地利用类型对坡面降雨入渗产流模式和优先流分布的影响。结果表明：(1)累积入渗量和优先流发育程度均表现为刺槐林地>草地>休耕地,刺槐林地优先流对总入渗的贡献是草地和休耕地的2.5—4.5倍,但优先流贡献均不超过10%,仍以基质流入渗为主。(2)4种用地类型降雨入渗主要补给地表60—70cm土层,前期降雨均匀增加表层土壤含水率,而后期降雨补给深层土壤水分的空间变异性显著增强。(3)刺槐林地产流量及径流系数均显著小于草地和休耕地,且前期含水量对20年刺槐林地的影响较小,而显著影响草地和休耕地径流系数。(4)直径d<1mm的细根显著促进降雨入渗和优先流发育,而d>5mm的粗根与入渗量和基质流量呈显著负相关。较高的土壤初始含水率、容重和粘粒含量会抑制入渗和优先流的发生。研究说明不同土地利用类型将改变降雨入渗产流过程及土壤水运动形式。