球形红杆菌W1分批发酵和恒化培养的研究

本文对球形红杆菌Ｗ１的培养方式进行了研究。由分批培养确定了适于常规发酵的培养基及培养条件。恒化培养该菌的最大生长速率Ｐ＝３．８ｇ／ｌ．ｈ;最适稀释率Ｄ＝０．１５０ｈ＾－１;最大比生长速率为０．２０ｈ＾－１;饱和常数Ｋｓ＝２．８２ｇ／ｌ。恒化培养可获得比分批培养高的生长速率。     

蓝光诱导促进黑曲霉产糖化酶的研究

考察了蓝光对黑曲霉产糖化酶的影响并采用扫描电镜观察蓝光下黑曲霉形态发育过程,结果表明,与黑暗对照组相比,蓝光处理使菌丝粗壮,孢囊增大,分生孢子发育提前,黑曲霉糖化酶活力增加,孢子发育和产糖化酶的进程有一定的对应性。黑曲霉在黑暗下生长至36h时,经蓝光诱导糖化酶产量提高更为明显,提示了黑曲霉存在一个对蓝光反应产生最适光感应的发育阶段,对于光调节黑曲霉产糖化酶来说,蓝光诱导的光强由弱到强,比持续蓝光培养或采用较高光强诱导效果更好,表明黑曲霉产糖化酶存在一种光适应机制,能够感应和适应光强度变化,调节其自身代谢。从抑制性扣除杂交实验和蓝光光强变化对差异基因表达的分析来看,糖化酶基因以及呼吸链中部分氧化还原酶基因在蓝光诱导下表达皆有增强,蓝光信号转导影响了核基因编码的线粒体呼吸链相关酶基因表达水平,交替氧化酶可能参与了蓝光信号途径,影响了黑曲霉产糖化酶和孢子发育。研究结果可为在现有水平上应用蓝光调节提高糖化酶产量找到新的技术突破口和提供新思路。     

黑曲霉产糖化酶黑箱模型的构建和应用

利用碳限制恒化实验研究了黑曲霉生长和糖化酶生产之间的相关性,结果表明当比生长速率低于0.068 h–1时,菌体生长与产酶是相关的,当比生长速率大于0.068 h–1时,菌体生长与产酶不相关。根据恒化实验结果获得黑曲霉葡萄糖底物消耗的Monod动力学模型,并结合葡萄糖和氧消耗的Herbert-Pirt方程和产物形成的Luedeking-Piret方程构建黑曲霉产糖化酶的黑箱模型。应用该模型设计指数补料分批发酵实验控制菌体比生长速率在0.05 h–1,使糖化酶的得率最高达到0.127 g糖化酶/g葡萄糖,并成功地使用模型描述了黑曲霉产糖化酶的发酵过程。实验值和模拟值进行比较表现出很好的适用性,表明黑箱模型可以用于指导黑曲霉产糖化酶发酵过程的设计和优化。     

膜生物反应器连续发酵法制取甲醇及其发酵动力学初探

采用膜生物反应器系统连续发酵制取甲醇能够及时分离产物,有效抑制甲醇对细胞的毒副作用,因此延长稳定期产甲醇的时间以提高产量。本文对比间歇发酵,研究了不同稀释率0．05h^-1～0．13h^-1下连续发酵的甲醇生成和甲烷氧化菌株Methylomonas．QJ16生长状况,并且初步探讨了该菌株的生长、甲醇形成的动力学特性。结果表明,稀释率为0．1h^-1时,菌体积累和甲醇的体积产率均较高,最长连续发酵持续时间为300h左右;描述连续发酵过程的动力学模型,菌体生长和产物合成的曲线拟合优度分别为0．991、0．994,基本反映了该甲烷氧化菌株连续发酵过程的动力学特征。     

产肌氨酸氧化酶菌株的分离及发酵条件研究

在本研究工作中分别从42℃的恒化富集培养物和30℃的分批富集培养物中分离到4株产肌氨酸氧化酶（SOX）的节杆菌。对所产SOX的特性分析表明,从42℃恒化培养物中分离得到的菌株42-1所产的酶比分批培养法分离得到菌株的酶具有高的热稳定性和低的Km值。对菌株42-1产酶发酵条件的研究表明,SOX可以被诱导物如肌氨酸、肌酸、肌酐和氯化胆碱诱导产生。在发酵过程中适当减少通气量对SOX的产生有显著的促进作用。葡萄糖等容易利用的碳源的存在对SOX的合成不产生降解代谢产物抑制作用,而尿素的存在则对SOX的生成有强的抑制作用。因而菌株42-1分解肌酸的主要作用是为细胞提供生长所需的氮源。     

基于比速率及代谢流的黑曲霉突变株和野生株分析

黑曲霉具备优异的外源蛋白表达和分泌能力,从而被广泛应用于工业酶制剂的生产。通过研究黑曲霉突变株和野生株在相同培养条件下生理参数和代谢流的差异,确定了黑曲霉合成糖化酶过程中的限制性因素。宏观动力学分析发现,较之野生株,突变株具有较高的最大比生长速率,并且副产物得率降低了90%,底物利用率提高了近30%,表明突变株与野生株在碳源分配和产物转化率上具有明显的差异。利用流平衡分析（FBA）计算胞内代谢通量分布,发现还原力和核糖的供应水平是限制菌体合成的主要因素,而前体氨基酸是合成糖化酶最主要的限制性因素。这些研究结果为后续发酵工艺优化和菌株基因改造提供了有益的思路。     

H_2O_2对黑曲霉氧化胁迫机理的研究

旨在探究H_2O_2胁迫下,黑曲霉的氧化应激响应,为控制黑曲霉生长和赭曲霉毒素A(OTA)合成提供依据。测定黑曲霉菌体生长、OTA合成、胞内活性氧(ROS)和脂质过氧化水平,以及抗氧化酶活性。H_2O_2能够抑制黑曲霉生长,且抑制作用具有剂量相关性;能促进其合成OTA,尤其是生长第4天时最为明显;能提升胞内ROS水平和丙二醛(MDA)含量;引起胞内过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)的活性增高,其中在生长第5天CAT酶活提高显著,生长第6天GPX酶活提高显著;但对超氧化物歧化酶(SOD)活性无显著影响。菌体通过提升胞内抗氧化酶活性及毒素的合成来平衡胞内过多的活性氧,从而在氧胁迫下维持菌体生长及代谢。     

黑曲霉糖化酶基因表达调控的研究 Ⅰ.高产及低产菌株糖化酶表达的总体分析和比较

对黑曲霉(Aspergillus niger)高产菌株T21和原始菌株3.795糖化酶的基因表达从菌体生长、酶形成动力学、glaA基因拷贝数、糖化酶mRNA含量及其稳定性等多个方面进行了分析和比较。T21和3.795糖化酶的大量产生均自菌体生长的静止期开始。培养72h后,两者的菌体浓度相同,但T2l产生的糖化酶量为3.795的10～17倍,说明糖化酶产量的差异不是因生物量或酶起始合成期不同引起的,而是由于细胞内酶表达量不同引起的。Northern杂交显示T21总RNA中糖化酶mRNA含量为3.795的4.3～4.4倍.两菌株glaA基因拷贝数及糖化酶mRNA的稳定性分析结果排除了这两个因素的影响,因此T21糖化酶mRNA含量的增加主要是glaA基因转录水平提高的结果。T21与3.795之间糖化酶水平差异(10～17倍)与糖化酶mRNA水平差异(4.3～4.4倍)的不一致性,提示T21和3.795之间除转录水平外可能还存在着翻译水平上的差异(2～4倍)。此外,T21和3.795均存在着对糖化酶基因表达的碳源调控机制,根据两者在淀粉、麦芽糖和葡萄糖培养条件下所产生的mRNA比均为4:3:2,可以认为,这种调控作用发生在转录水平上,并且具有相同的调控方式。     

蓝光促进黑曲霉分生孢子发育和产糖化酶的研究

以黑暗为对照 ,研究了不同光质对黑曲霉产糖化酶及生长发育的影响。持续蓝光作用下 ,孢子萌发后菌丝较粗 ,菌丝细胞顶端膨大显著 ,菌丝细胞膜的通透性增加 ,残糖消耗快 ,孢子和孢子穗增大。在 3(4d时 ,蓝光下菌丝产糖化酶活力最高达 6 6 0 (30U mL ,比黑暗高出了 15. 4 % ,生物量增加了 4 9. 4 8% ,菌丝细胞可溶性蛋白含量提高了10 0. 5 6 % ,尤其是在开始产孢子的阶段 ,蓝光下黑曲霉产糖化酶活力、生物量有很大提高。研究表明 ,蓝光明显促进黑曲霉分生孢子发育和产孢阶段包括糖化酶在内的多种淀粉酶活力的迅速增加。     

葛根芩连汤在模拟胃肠液中对微生物生长的影响

目的探究葛根芩连汤在模拟胃肠液中对微生物生长的影响。方法在模拟胃肠液中分别加入消化液10%量的金黄色葡萄球菌、大肠埃希菌、沙门菌、产气杆菌、黑曲霉、米曲霉、青霉和汉逊德巴利酵母,然后加入生药浓度为1 g/mL的葛根芩连汤水煎液,37℃恒温培养。分别在0、1、2和4 h吸取1 mL培养液做稀释平板计数。结果体外模拟肠液中,葛根芩连汤对金黄色葡萄球菌、大肠埃希菌、沙门菌、产气杆菌、黑曲霉、米曲霉和青霉有较强的抑制作用,而对汉逊德巴利酵母的生长则为先促进后抑制,并且在2 h时对黑曲霉、米曲霉、青霉和汉逊德巴利酵母的抑制效果最显著;在模拟胃液中,葛根芩连汤对金黄色葡萄球菌、大肠埃希菌、沙门菌、黑曲霉、青霉和汉逊德巴利酵母均有一定的抑制作用,而对产气杆菌无明显影响。结论葛根芩连汤在模拟胃肠液中对金黄色葡萄球菌、大肠埃希菌、沙门菌、黑曲霉、米曲霉、青霉和汉逊德巴利酵母等均具有一定的抑制作用,在模拟肠液中对产气杆菌抑制作用明显,而在模拟胃液中对其抑制效果不明显。     

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.