钛离子注入井冈霉素生产菌株的诱变效应

探讨了利用金属Ti 离子注入井冈霉素生产菌的生物学效应,比较了不同的注入能量与注入剂量对菌株突变效果的影响.在注入能量为15 keV,剂量为1.5×1015 个/cm2离子的诱变条件下,筛选到一株井冈霉素高产菌株C3-6,其发酵生产井冈霉素A组分的效价为19 684 μg/mL,比出发菌株提高41.3%.经多次传代实验表明该菌株的遗传稳定性较好.     

紫外诱变选育恩拉霉素高产菌株

本研究采用紫外诱变育种技术对一株产恩拉霉素抗真菌链霉菌(Streptomyces fungicidicus)F110进行了诱变处理,经链霉素抗性、利福霉素B抗性以及双重抗性筛选,共获得了132株抗生素抗性突变株,其中26株突变菌株的恩拉霉素产量与出发菌株相比均有明显提高。摇瓶发酵条件下,突变株SR93的恩拉霉素产量最高可达2 400μg/m L,与出发菌株相比提高了38%。传代结果表明:该突变株产素水平稳定,因此具备较好的开发及工业应用价值。     

氮离子注入选育阿维拉霉素高产菌株的研究

以提高产绿链霉菌(Streptomyces viridochromogenes)SV-1产阿维拉霉素(Avilamycin)产量为目的,采用低能氮离子注入技术,辅之以链霉素抗性筛选法进行诱变选育研究。结果表明,“马鞍”区域即注入剂量范围在3×10~(15)～5×10~(15)ions/cm~2诱变效果最佳,菌株的抗药性突变与产量突变密切相关,链霉素抗性筛选法具有可行性。在摇瓶条件下,最终获得稳定性良好,阿维拉霉素产量达到83．5mg/L,较出发菌株提高195%的突变株SVT-45。实验表明,离子注入技术是一种有潜力的微生物诱变育种新方法。     

梅岭霉素产生菌抗药性突变标志诱变筛选模型的初步研究

本文通过梅岭霉素 (Meilingmycin)产生菌南昌链霉菌NS 4 1 80菌株孢子对 6种抗生素敏感性测定 ,采用诱变剂EMS四种不同诱变剂量对菌株孢子进行诱变处理 ,诱变处理的孢子涂布在含致死浓度链霉素的高氏平板上。然后从抗药性突变标志菌株中进一步筛选梅岭霉素高产菌株。在 150 0多个抗药性突变株中通过初筛获得了比诱变出发菌株的产素能力提高 50 %以上菌株。通过诱变剂量分别与抗药性突变率和突变株产素产量的变势统计分析表明 ,菌株抗药性突变与产素突变密切相关 ,产素突变的EMS诱变剂量高于抗药性突变诱变剂量 ,在 0 .0 3mol/LEMS剂量作用下 ,菌株致死率为 99.4 3% ,抗药性突变率为 0 .0 4 4 0 % ,建立了梅岭霉素产生菌抗药性突变标志诱变推理性筛选模型。为南昌链霉菌高产菌种选育研究作了有益的尝试 ,并有助于其它链霉菌属的抗生素产生菌育种研究。     

氮离子诱变筛选内切葡聚糖酶高产菌株及其基因突变研究

目的：离子注入枯草芽孢杆菌筛选高产内切葡聚糖酶突变菌株,同时进行其酶活性研究,并克隆该基因,研究离子注入对其诱变效应。方法：低能氮离子重复注入枯草芽孢杆菌,筛选获得1株高产内切葡聚糖酶突变菌株Bac11。DNS法测定酶活性。PCR扩增获得出发菌株Bac01和突变菌株Bac11内切葡聚糖酶基因,并对核酸序列及预测氨基酸序列进行多重比对。结果：突变菌株Bac11内切葡聚糖酶活性从93.33IU提高到381.89IU。多重比对Bac01和Bac11内切葡聚糖酶基因编码区1500bp序列,当中有10个碱基发生突变,预测氨基酸序列中有5个氨基酸残基发生变化,且都在其基因纤维素结合域部分。结论：低能氮离子重复注入对枯草芽孢杆菌内切葡聚糖酶活性及其基因有明显的诱变累加效应。     

离子注入选育霉酚酸高产菌株及其发酵条件研究

离子注入技术是20世纪80年代兴起的一种综合诱变技术,其应用于生物工程已取得了丰硕成果,但在霉酚酸产生菌的诱变育种中的应用还未见报道。短密青霉菌(Penicillium brevicompactum)M_51是从土壤中分离得到的MPA产生菌F_663经过紫外线、微波等诱变处理得到的。为获得霉酚酸的高产工业菌株,进一步对该菌株进行了离子注入诱变处理。用15keV氮离子分5个剂量进行处理,结果显示,随离子注入剂量增加,存活率呈现较明显的下降_上升_下降的“马鞍型”变化趋势。在剂量为140×2.6×1013ions/cm2时,菌株变异率及正变率均最高,分别达到88.9%和63.4%。用HPLC定量测定发酵液中霉酚酸的含量,筛选到产霉酚酸能力提高30.1%的突变株M_163。经过连续传代试验,其遗传性状稳定。对发酵条件的优化结果显示最佳种龄为24h;用正交试验方法对发酵培养基中的碳、氮源进行优化,得到较优配方。突变株M_163在最优发酵条件下,霉酚酸摇瓶发酵单位可达2819μg/mL。野生菌株F_663的MPA产量为133μg/mL,经过5代诱变育种及发酵条件优化,产量提高了20.2倍。     

N~+离子注入选育高产氨基酰化酶菌株的研究

选用N~+离子注入的方法对米曲霉(Aspergillus oryzae)CICC 2339-1进行诱变育种,通过三角瓶发酵法筛选氨基酰化酶高产株。N~+离子注入选择能量为10 KeV,剂量在(1.30～4.94)×10~(15)ions/cm~2之间。根据剂量与存活率以及剂量与突变率曲线选择最佳的注入剂量。通过三角瓶发酵筛选得到突变菌株SN-110-15其酶活提高率为139.5%,诱变试验效果显著。     

恩拉霉素生产菌株的遗传改造

【目的】提高杀真菌素链霉菌发酵生产恩拉霉素的产量。【方法】利用定点突变技术,对恩拉霉素生产菌株杀真菌素链霉菌F1中影响细胞次级代谢及抗生素合成的核糖体S12蛋白的编码基因rps L进行改造,将第43位的赖氨酸(Lys)分别替换为天冬酰胺(Asn)和精氨酸(Arg),并对改造菌株L-M1(Asn43)和L-M2(Arg43)的生长特性、抗生素合成以及摇瓶发酵性能进行研究。【结果】与野生型菌株相比,改造菌株的生长特性及生理生化特性均发生了明显的改变:产孢周期明显缩短,野生型菌株在MS培养基中,28°C下需要培养5-7 d后才能产生孢子,而在相同条件下,改造菌株3 d后就能产生大量的孢子;恩拉霉素产量相对提高,摇瓶发酵条件下,改造菌株L-M1(Asn43)和L-M2(Arg43)的恩拉霉素产量分别可达到1 334 U/m L和1 456 U/m L,与野生型菌株F1相比分别提高了11.9%和22.1%。【结论】通过遗传改造,恩拉霉素的产量得到了提高,为其他位点的遗传改造提供了可行性。     

农用抗生素2-16高产菌株选育及发酵优化组合研究*

对农用抗生素2-16产生菌(Streptomyces ahygroscopicusvar.huangshanensis)依次进行紫外线诱变、NTG诱变、低能碳离子注入处理,筛选获得高产菌株515号,效价较出发菌株0号提高223.10%。利用SAS软件提供的Plackett-Burm an设计和响应面分析法对菌株515号的发酵培养基进行优化,采用优化培养基后效价较原始培养基提高38.53%。     

通过获得链霉素抗性基因突变株筛选小诺霉素高产菌株

通过链霉素对小诺霉素产生菌 (Micromonospora purpura) 49 1 2 #菌株孢子致死浓度的测定 ,采用诱变剂EMS 3种不同诱变剂量对菌株的孢子进行诱变处理 ,诱变处理的孢子涂布在含链霉素致死浓度的改良高氏平板上 ,获得大量的链霉素抗性基因突变株 ,然后从链霉素抗性基因突变株进一步筛选小诺霉素高产菌株 ,获得小诺霉素菌株 49 1 2 3菌株。在摇瓶条件下 ,其产小诺霉素生物活性单位比出发菌株 49 1 2 #的摇瓶发酵单位提高了 40 %以上。小诺霉素的组分比由出发菌株的C2b∶C1a的 5∶5提高到 8∶2。C2b有效组分提高了 30 %;链霉素抗性基因突变与小诺霉素发酵单位突变之间 ,小诺霉素正突变率达到 40 %,负突变率达 2 6%,正突变大于负突变     

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.