中性植酸酶产生菌的激光复合诱变筛选

采用激光复合诱变方式筛选产中性植酸酶的大肠杆菌(Escherichia coli)、枯草杆菌(Bacillus subtilis),混合波长λ=1.06 0.53μm,辐照时间1 m in,辐照功率15 W;酶的细胞定位实验表明,所产中性植酸酶是胞外酶;酶学特性测定表明,大肠杆菌所产植酸酶酶反应最适pH为7.4,最适温度为37℃,枯草杆菌所产植酸酶反应最适pH为7.4,最适温度为37℃;酶学性质分析表明,大肠杆菌所产植酸酶具有一定的pH适性和一定的温度耐受性。     

激光诱变筛选高产植酸酶黑曲霉菌株的研究

用1.06um,15KHz高重复率声光调QNd：YAG激光以20W和15W的辐照功率分别照射产植酸酶的黑曲霉孢子液和原生质体液不同时间,检定再生菌落数并经透明圈初筛和摇瓶复筛,测定诱变菌株所产植酸酶酶活。结果表明：20W的功率辐照黑曲霉孢子1′以上,致死率近乎100…,15W功率辐照原生质体液20″-4′,存活率在8.571％-117.14％之间,正变率在27.45％-100％之间,正变辐度60.69％-124.96％,说明原生质体比孢子耐受激光诱变的能力强,并且诱变效果好。筛选到了一株酶活提高达3.75倍的单个变异菌株。     

脱落酸高产菌的激光诱变效应研究

本实验对比紫外、 Ｈｅ Ｎｅ 激光、 Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光对脱落酸产生菌的诱变效果。紫外诱变正变率为 ３８４％ ,负变率 ７６９％ ; Ｈｅ Ｎｅ 激光诱变正变率为 ５６％ ; Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光诱变正变率为１９６％ 。 Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光诱变辐照次数在 ４００ 次时效果较好,所得高产株效价提高率可达 ６０％ 以上     

不同波长的激光对水稻胚芽中可溶性蛋白质及同工酶的作用

用波长0.3371、0.6328μm和1.06μm的激光器,用不同剂量(5、15、50min和3、7、9个脉冲),照射水稻干胚,使其萌动生长72hr后,再用聚丙烯酰胺凝胶电泳法,分析胚芽中可溶性蛋白质,酯酶同工酶和过氧化物酶同工酶。结果证明,波长0.3371～1.06μm的激光辐照水稻种胚,都能使同一生物大分子的活性和分子结构产生变异。由此认为,不能用辐照离体制备液所得结果去预言在活体上的反应。     

激光参数对果胶酶产生菌变株产酶特性的影响

采用Ｋｒ＾＋、Ａｒ＾＋、Ｈｅ－Ｎｅ、ＬＤ、ＹＡＧ倍频等多种激光辐照果胶酶产生菌－黑曲霉。在同一波长、同一照射剂量下,不同辐照功率与时间的组合将产生变株产酶特性的不同变化,实验中存在着一个最佳辐照时间与功率的组合。在同一照射剂量、同一辐照功率与时间组合的条件下,变株果胶酶活变异率随波长变化基本呈线性关系。紫外光、可见光产生的酶活正变率与最大增幅高于红外光。激光的连续或不同调制频率的输出方式可能影响黑     

皮秒激光微束仪的研制

本文分析了激光微束仪的设计要点,通光孔径的选取,聚焦系统与观察系统的齐焦,微小光斑获得等。激光微束仪的光源是具有多次谐波功能的皮秒Nd~(+3)YAG激光器,工作频率(10PPS),输出能量为50毫焦耳,平均脉宽为30PS的基波序列脉冲,可选波长为1.06μm、0.53μm、0.355μm、0.266μm,谐波晶体用偏硼酸钡(β-BaB_2O_4),简称BBO。     

曲酸产生菌激光诱变效应的研究

采用经紫外线(UV)、^60Co、亚硝基胍(NTG)复合诱变得到的黄曲霉曲酸产生菌(UCN7—12),进行激光诱变处理。研究证实在经过UV、^60Co、NTG诱变处理后,黄曲霉突变株用He—Ne激光与YAG激光进行诱变处理仍能提高产酸率,其中He—Ne激光辐照处理20min,正变率为12．1％,产量提高约13％。YAG激光辐照处理300sec,正变率16．7％,产量提高18．3％。说明上述两种激光对黄曲霉曲酸产生菌有一定的诱变效应。     

倍频Nd：YAG激光对钝顶螺旋藻的诱变效应

利用倍频 Nd:YAG激光 (波长 53 2 nm,功率 50 0 m W,功率密度 1 60 m W/cm2 )诱变钝顶螺旋藻 ,辐照时间为 1 5min、1 0 min、5min通过测定藻丝形态参数、叶绿素 a、β 胡萝卜素、生长速度 ,比较倍频 Nd:YAG激光对钝顶螺旋藻生长的影响。实验结果表明 :与出发株相比 ,经倍频 Nd:YAG激光辐照后 ,藻丝形态发生变化 ,藻丝长、螺旋数、螺旋长变小 ;1 5min,1 0 min辐照组出现螺旋变松驰 ;1 0 min,5min辐照组促进藻的生长和叶绿素 a含量提高 ,使生长速度提高。三个诱变时间剂量都有利于 β 胡萝卡素积累 ,含量增幅最高达 2 2 .3 %。     

用原生质体诱变选育高植酸酶活的黑曲霉变异株

将 2株黑曲霉菌株 (I,II)在诱导产植酸酶的条件下分别制备成原生质体 ,并考察其原生质体形成及再生 ,经紫外诱变后 ,发现涂平板的黑曲霉 (II)原生质体在再生过程中菌落形态发生明显变化。考查突变菌种的植酸酶酶活 ,筛选到其中一个变异株比原始黑曲霉 (II)亲本株的植酸酶酶活提高了 2 .2倍。     

一株高产细胞表面植酸酶酵母的实验研究

对一株高产细胞表面植酸酶酵母突变株WZ4菌的细胞植酸酶进行了研究。探讨了菌体生长与产酶的关系。结果表明:菌体在培养的前期植酸酶酶活很低,培养30h后酶活迅速增加,酶活在菌体生长的平衡期达到最大,该菌产植酸酶为非生长偶联型。在此基础了解WZ4菌细胞植酸酶的性质,实验表明:该酶的最适pH为5,最适温度为50℃,Km(以植酸钠为底物)为0666mmolL。通过磷对产酶影响因素的实验研究,初步得到WZ4菌产植酸酶受控于培养基中的磷浓度的结论,即最大产酶磷浓度为05mg100ml,当磷浓度大于10mg100ml时产酶被完全阻遏。     

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.