利用制霉菌素溶缩处理高频率地检出黑曲霉营养缺陷型突变株

以亚硝酸诱变处理黑曲霉Ｎ３４３和黑英霉ＵＶ－１１的分子孢子,然后将它们培养在它们培养基平板上至第二代分生孢子生长,收集这些孢子以制霉菌素浓缩处理,结果以３．８－０．３％的高频率和到１９株稳定的营养缺陷型突变株：从黑曲霉Ｎ３４３获得３株维生素类的缺陷型,它们分别为双缺或参缺;从黑曲霉ＵＶ－１１获得１６株特殊遥脯氨酸营养缺陷型,进一步分析表明这是由于从谷氨酸合成脯所酸或精氨酸的代谢阻断所致。     

利用原生质体融合技术提高黑曲霉产酶活力的研究

以黑曲霉Ｎ３４３和ＵＶ—１１为出发株,分别经亚硝酸诱变处理,再以制霉菌素浓缩处理,从中筛得３株维生素缺陷型和１株氨基酸缺陷型的突变株。选取来自Ｎ３４３的突变株ＮＢ_３（Ｂ_１^－,ＰＰ^－,ＦＡ^－）和来自ＵＶ—１１的突变株ＵＢＩ（Ｐｒｏ^－）为融合亲本,在研究其原生质体释放和再牛条件的基础上,以ＰＥＧ诱导进行了原生质体融合。用直接选择法检出９８个融合子,经过筛选得到两株稳定的融合子：Ｆ     

黑曲霉UB4和NB3的原生质体制备及其再生条件的研究

以两株黑曲霉营养缺陷型突变株ＵＢ４和ＮＢ３为材料,对于其原生质体制备及其原生质体再生条件作了详细的研究,从中找到了合适的破细胞壁方法和培养条件,为尔后的黑曲霉原生质体的利用如融合或诱变育种等方面的研究奠定了基础。     

影响紫云英根瘤菌入侵和根瘤发育的exo基因的克隆及分析

紫云英根瘤菌菌株１０７的３个胞外多糖缺陷突变株ＮＡ－０１、０２、０４不具备诱导宿主植物紫云英结瘤的能力。以ＮＡ－０１突变位点的ＤＮＡ面为探针,从可互补这３个变种的ｅｘｏＲ’－１１质粒上亚克隆到２．６ｋｂ的ＤＮＡ片段。互补试验表明,２．６ｋｂ的片段不仅可纠正突变株的胞外多糖缺陷表型,而且使变种恢复诱导宿主植物形成有效根瘤的能力,２．６ｋｂ片段经Ｔｎ５定位突变后丧失这种恢复能力,表明该片段带有对应于３     

细菌感受态细胞摄取和分泌DNA的相关性研究I.含有质粒的枯草芽孢杆菌自然感受态缺陷突变株的诱变和分离

以携带ｐＵＢ１１０质粒的枯草芽孢杆菌ＢＲ１５１菌株为出发菌株,利用亚硝基胍作诱变剂,直接在ＬＢ平板上进行诱变。从２９４９个菌落中筛选出一个转化频率低于出发菌株２～３个数量级的突变株,并对其营养缺陷型、ＵＶ的敏感性及Ｋｍ抗性和质粒进行了检测,确证其转化能力降低为自然感受态缺陷而非营养缺陷型的改变或重组缺陷所致     

梧宁霉素产生菌诱变选育的研究

以不吸水链霉菌（Ｓｉｒｅｐｔｏｍｙｃｅｓａｈｙｇｒｏｓｅｌｃｎｓ）ＮＳ—２３为出发菌株。菌种斜面孢子萌动后采用紫外线（ＵＶ）、硫酸二乙酯（ＤＥＳ）、秋水仙素及加底物等物理化学因子进行诱变处理,经两代连续处理,从ＵＶ、ＤＥＳ的复合处理中选育出一株产素较高的突变株ＵＤＡ２５７－Ｃ－２４,产素效价比出发菌株提高了２９１．７２％     

丙型肝炎病毒北京株NS3基因的克隆及测序

用ＲＴ－ＰＣＲ方法从北京株丙型肝炎病毒中扩增出ＮＳ３区基因片段,该片段经ｐＧＥＸ－Ｔ载体克隆到大肠杆菌ＤＨ５α菌株中．经自动序列分析仪测出ＮＳ３基因的７２８ｂｐ长的核酸序列．发现在该片段中第３１位核苷酸发生Ａ→Ｔ突变,产生一个终止突变．这表明,丙型肝炎病毒北京株存在一定的变异,产生缺陷型病毒,这类缺陷型病毒的出现可能是丙型肝炎病毒持续性感染的原因之一．     

植酸酶高产菌的诱变选育

以黑曲霉ＭＡＯ２１为出发菌株,经紫外线,、亚硝基胍单独处理和复合处理,获得一植酸酶高产菌株ＵＮ－１２－１０。该菌株具有稳定的遗传性能,在经过优化的摇瓶培养基上发酵１０８ｈ,其植酸酶活力达到２９５０－３０１５ｕ／ｍｌ,是原始出发菌株的３．６倍。     

三株散发性戊型肝炎病毒变异株的部分序列比较

对三株散发性戊型肝炎病毒Ｃｈ－Ｔ１１、Ｃｈ－Ｔ２１、Ｃｈ－Ｆ４０的部分基因组做克隆测序,经比较发现与其它国内外ＨＥＶ株ＯＲＦ２部分相应核苷酸序列同源性在７８．３－８１．３,Ｃｈ－Ｔ２１与Ｃｈ－Ｔ４０的核苷酸同源性９８．８％,而Ｃｈ－Ｔ１１与前两者的同源性则分别为８９．８％和９０．２％。Ｃｈ－Ｔ１１、Ｃｈ－Ｔ２１、Ｃｈ－Ｔ４０与其它ＨＥＶ株相应氨基酸序列同源性在９５．８－９７．９％,它们之间的氨基酸     

L-赖氨酸产生菌FH128菌株的研究(Ⅰ)FH128菌株的选育及摇瓶发酵

以赖氨酸产生菌Ａ１１１（ＨＳ－、ＡＥＣｒ）为出发株,经化学诱变剂ＭＮＮＧ（Ｎ－甲基－Ｎ′－硝基－Ｎ－亚硝基胍）及单氟醋酸处理获得单氟醋酸抗性突变株Ｆ７９,摇瓶发酵产Ｌ－赖氨酸盐酸盐７．０％～７．５％,对糖转化率３８％～４０％,分别比Ａ１１１株提高约２５％及２０％。然后,再以Ｆ７９菌为亲株经ＭＮＮＧ及噻唑丙氨酸处理获得噻唑丙氨酸抗性突变株ＦＨ１２８,在适宜的培养条件下,摇瓶发酵产Ｌ－赖氨酸盐酸盐８．５％～９．５％,最高产酸率１１％,对糖转化率４５％～５０％。在１６Ｌ自控发酵罐发酵,产Ｌ－赖氨酸盐酸盐１２％～１４％,对糖转化率４０％～４５％;在２０～１００ｍ３发酵罐发酵,产酸率为８．５％～９．５％,对糖转化率４０％～４２％,提取总收率８０％～８５％,成品（饲料级Ｌ－赖氨酸盐酸盐）质量符合国家标准（ＧＢ８２４５－８７）。ＦＨ１２８菌株遗传性能稳定,营养要求粗放,工艺较简单,便于工业化,二年前已应用于工业生产。     

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.