嗜热甲烷八叠球菌的分离和生理特性

采用严格的Hungatc厌氧技术,从成都市郊区常温沼气池污泥中分离到嗜热甲烷八叠球菌(Methanosarcina thermophilia)CB菌株。CB菌株能够利用甲醇、甲胺和醋酸生长并产生甲烷,不能利用H2／CO2、甲酸作为碳源和能源。该菌株的最适生长温度为50℃,最适生长pH为7．0,最适合生长的Na+、Mg+、NH+4的浓度分别为20mM、50mM和300mg／L。青霉素和低浓度的乳糖酸红霉素(50g／m1)对CB菌株的生长无抑制,这有利于cB菌株的分离和纯化。酵母膏和污泥上清液都对该菌株的生长有一定的刺激作用,同时在生长过程中,酵母膏、胰化酪蛋白和维生素均可代替污泥上清液,这一点又不同于嗜热甲烷八叠球菌’M1菌株。     

热球菌目(Thermococcales)遗传操作系统研究与应用进展

热球菌目(Thermococcales)是一类分离自浅海热泉或者深海热液口的超嗜热微生物,包括火球菌(Pyrococcus)、热球菌(Thermococcus)、古老球菌(Palaeococcus)。研究其生命活动的分子机制,基因的功能等必须借助遗传操作系统。由于选择标记的限制,Thermococcales遗传操作系统落后于其他菌株。近年来,在Thermococcales发现了内源质粒并可以将其改造用作遗传工具。如在Thermococcus kodakarensis及Pyrococcus furious等菌株内都建立了成熟的遗传系统,并用于基因敲除以及基因表达。将就Thermococcales内源质粒的发现和遗传操作系统的发展与应用加以阐述。     

一株羽毛降解菌的分离与鉴定

【目的】从土壤中分离并鉴定羽毛降解菌,测定其生长最适温度及起始pH,并观察酶活动态。【方法】采用系列稀释法和选择培养基法筛选目的菌株,基于16S rRNA基因序列及Biolog方法鉴定其分类地位,利用全自动生长曲线分析仪监测菌株的最适生长条件,并通过测定蛋白水解活性观察其酶活动态。【结果】从混合羽毛的土壤样品中筛选到一株羽毛降解菌,命名为菌株GIMN1.015,初步判定该菌株属于芽孢八叠球菌属(Sporosarcina)。最适生长pH为9.0,温度为30°C。蛋白水解活性最高值出现在培养后96 h。【结论】菌株GIMN1.015在利用羽毛角蛋白资源中具有潜在的应用价值。这是芽孢八叠球菌在羽毛降解方面的首次报道。     

高温海藻床中微生物的分离鉴定及其耐热、耐盐特性研究

【目的】对印度洋卡利安达岛海洋热泉周边的高温海藻床中的微生物进行分离培养和16S rDNA种属鉴定,并研究其耐热和耐盐特性。【方法】采集海藻床中马尾藻、沉积物和海水样品,采用MGYTC培养基,分别于55°C和30°C对样品中的微生物进行培养和分离纯化;采用16S rDNA鉴定种属并构建进化树;研究培养温度和盐度对几种菌株生长的影响。【结果】共获得4个纲、9个属的12种菌株,与已知种属的相似度高于98%。芽孢杆菌纲嗜热放线菌科2个属的菌株和芽孢杆菌属菌株在55°C培养时获得,为嗜热菌株;其中高温放线糖莱斯菌(Laceyella sacchari)和热噬淀粉芽孢杆菌(Bacillus thermoamylovorans)可以在0 90的盐度范围生长。γ-变形菌纲希瓦氏属的Shewanella upenei、Shewanella algidipiscicola和鲍希瓦氏菌(Shewanella haliotis)可适应30°C 55°C的生长环境。【结论】研究获得的菌株,具有耐热、耐盐或对温度适应范围广等特性,有望成为生物技术领域的新资源;分离获得的Tepidibacter formicigenes,深海微小杆菌(Exiguobacterium profundum)和魔鬼弧菌(Vibrio diabolicus)曾被报道来源于深海热液区,这对于阐明海洋热泉与深海热液环境的内在联系提供了参考。     

一株高效降解木糖的耐酸、嗜热厌氧杆菌的生理特性及产物分析

【目的】分离高效降解木糖的嗜热厌氧杆菌菌株,用于发酵生产生物燃料乙醇,为后继的构建基因工程菌株及联合生物工艺提供材料。【方法】运用亨盖特厌氧操作技术从胜利油田油层采出液两年的富集样中分离到一株嗜热厌氧杆菌xyl-d。采用形态学观察、生理生化指标鉴定及基于16S rRNA的系统发育学分析确定其分类地位。【结果】菌株xyl-d为革兰氏阴性厌氧杆菌,菌体大小为(1.35-5.08)μm×(0.27-0.40)μm,单生、成对或成簇生长,芽胞圆形,端生。温度生长范围30-85℃(最适温度65℃);pH范围3.0-10.0(最适pH 7.5);NaCl浓度范围0%-4%(最适NaCl浓度2.0%)。发酵D-木糖的产物是乙醇、乙酸、CO2及少量的异丁醇、丙酸。菌株xyl-d的(G+C)mol%含量为45.6%,与热厌氧杆菌属模式菌株威吉利热厌氧杆菌(Thermoanaerobacter wiegelii)DSM10319T及嗜热乙醇杆菌(Thermoanaerobacter ethanolicus)DSM2246T的16S rRNA序列相似性均为99.3%。菌株利用D-木糖产乙醇的最佳初始pH为8.5;少量酵母粉能刺激生长并显著提高发酵D-木糖的产醇率,使乙醇成为主要的发酵产物;培养基中乙醇浓度达到7%(V/V)时菌体生长受到抑制,最佳生长条件下D-木糖的降解率可达91.37%,最佳产醇条件下发酵1摩尔D-木糖可产生1.29摩尔的乙醇。【结论】菌株xyl-d是从特殊生境(油藏)中分离到的一株高效降解D-木糖的耐酸、嗜热的厌氧杆菌,其为半纤维素降解产乙醇的联合生物工艺提供了菌源。     

基于比较基因组学分析嗜热链球菌的遗传多样性和防御系统

【目的】嗜热链球菌(Streptococcusthermophilus)是发酵乳制品的基础发酵菌种之一,全基因组水平解析嗜热链球菌的遗传多样性和工业发酵特性对于优良发酵菌株的筛选意义重大。【方法】本研究通过比较基因组学方法对27株嗜热链球菌的遗传多样性和防御系统进行分析。【结果】全基因组分析结果显示嗜热链球菌群体内具有较高的遗传多样性;基于核心基因集构建的系统发育树划分为2个分支,其中分支2菌株缺乏完整的组氨酸合成途径,经验证,分支2菌株在缺乏组氨酸的培养基中不能正常生长。通过对嗜热链球菌不同菌株的防御系统进行分析发现,同类型的CRISPR基因座和限制修饰系统在基因组中出现的位置相对固定。CRISPR-Cas系统(P<0.05,r=0.43)和限制修饰系统(P<0.01,r=–0.59)的数量与编码转座酶基因的数量均显著相关,表明嗜热链球菌为了阻止外源DNA入侵会进化出多种防御系统来保护自身遗传完整性。此外,分支1菌株的CRISPR-Cas系统数量极显著(P<0.001)多于分支2,而限制修饰系统无显著差异,表明分支1菌株在噬菌体抗性方面可能更具优势。【结论】本研究基...     

柑桔全爪螨高致病力菌株芽枝状枝孢霉的生物学特性研究

【目的】明确柑桔全爪螨Panonychus citri(Mc Gregor)高致病力菌株芽枝状枝孢霉Cladosporium cladosporioides(CQBBW3)的生物学特性。【方法】通过单因素试验,测试了不同培养基、碳源、氮源、温度及pH对CQBBW3菌株生长和产孢的影响。【结果】CQBBW3菌株的LC50为4.66×108个孢子/m L,LT50为6.2353 d。最佳生长培养基是淀粉琼脂培养基,最适产孢培养基为察氏培养基;菌丝生长最适碳源和氮源为甘露醇和甘氨酸,产孢最适碳源和氮源为乳糖和赖氨酸;最适生长温度为25℃,最适产孢温度为15℃和30℃;最适生长pH值为6.0~8.0,最适产孢pH值7.0。【结论】CQBBW3菌株对柑桔全爪螨有较好的杀虫活性,喜好25℃、中性、富含有机营养的环境。本研究为菌株快速培养及其真菌杀虫制剂的开发与田间应用奠定基础。     

基于内源III-B型CRISPR-Cas系统构建超嗜热火球菌Pyrococcus yayanosii A1的基因敲降系统

【目的】亚氏火球菌(Pyrococcusyayanosii)A1菌株的最适生长温度为98°C,最适生长压力为5.2×104Pa,是研究此类严格厌氧、超嗜热和兼性嗜压古菌的环境适应性机制的良好材料。本研究基于P. yayanosii A1基因组中III-B型CRISPR-Cas系统,旨在建立可应用于此类古菌的基因表达敲降系统(geneknock-downsystem)。【方法】人工构建的mini-CRISPR簇,由内源性CRISPR簇Group1的重复序列(repeats)和待敲降的淀粉酶基因(PYCH_13690)中的原间隔序列(protospacer)组成。将该mini-CRISPR簇插入到具有辛伐他汀抗性的穿梭载体p LMOShhp中,使之转录与目的基因m RNA匹配的cr RNA,引导Cmr复合物对其进行切割。【结果】使用高静水压(HHP)诱导型启动子Phhp诱导mini-CRISPR簇表达时,淀粉酶基因的m RNA数量在5.2×104Pa静水压时下调到原来的67.05%,在1.0×102Pa静水压时下调为原来的49.69%;而使用组成型启动子Phmtb诱导mini-CRISPR簇表达时,淀粉酶基因的m RNA数量在5.2×104Pa静水压时下调为原来的58.48%,在1.0×102Pa静水压时下调为原来的23.97%。使用鲁戈氏碘液显色法对这两类基因表达敲降突变菌株的培养物中残留的淀粉含量进行分析,结果显示突变菌株的淀粉降解能力明显降低。【结论】在P. yayanosii A1中建立了基于内源Ⅲ-B型CRISPR-Cas系统的基因敲降系统,可以用于抑制此类超嗜热嗜压古菌体内基因的表达。     

耐盐硫氧化菌的筛选、鉴定及脱硫性能研究

【目的】从典型自然环境中筛选耐盐高效硫氧化菌,研究其生长特性,并进行初步脱硫实验。【方法】以硫代硫酸钠为唯一能源底物的培养基富集脱硫菌,经过3次平板划线培养、纯种分离后得到纯种培养。经过革兰氏染色、平板菌落形态观察及形态学特征研究,并结合16S rRNA基因序列分析及分子系统发育树的构建结果,确定菌株的种类。【结果】从上海外高桥某发电厂冷却水池中筛选分离出一株硫代硫酸盐去除率高、耐盐性较强的细菌,命名为CYJN-1。该菌为革兰氏阴性菌,短杆状,鉴定为那不勒斯菌(Halothiobacillus neapolitanus)。H. neapolitanus CYJN-1具有较强适应盐度变化的能力,菌株生长的盐度范围为0?5% (NaCI,质量体积比)。菌株最适生长条件为：温度30 °C、pH 7.0、底物浓度为20 g/L。在此条件下,该菌对硫代硫酸钠的去除率可达98%。【结论】H. neapolitanus CYJN-1耐盐性较强,硫代硫酸盐去除率高,在生物脱硫、生物冶金等领域都具有潜在的应用前景。     

酱醪嗜盐四联球菌的分类及特性研究

【目的】对酱油酱醪来源的嗜盐四联球菌进行分类,并比较菌株的生理特性。【方法】采用多位点序列分型和糖类代谢聚类分析相结合的方法对菌株进行分类,通过菌株对环境耐受性分析研究菌株的生理特性。【结果】酱醪来源的12株嗜盐四联球菌被分为两个类群,菌株所属类别与其分离的原生环境存在一定的关联性。嗜盐四联球菌C25、C33、C3、R55耐高盐及高糖能力均较强,菌株C1、R44和R23耐高盐能力较强。虽然嗜盐四联球菌普遍不耐酸,但是菌株C33和R44在酸性培养体系(pH 5.0)中仍能正常生长。较低的培养温度(15℃和25℃)对嗜盐四联球菌的生长有显著抑制。【结论】采用基因型与表型结合的方式成功将酱醪来源的嗜盐四联球菌归为2个类群,不同类群的菌株在耐高渗等生理特性上具有差异性。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.