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以亚硝基胍(MNNG)诱变处理大肠杆菌ASI.358,获得蛋氨酸缺陷型(Met-)突变株,从中得到一株B2851菌,能在培养基中积累少量苏氨酸。通过连续诱变,得K1-73菌株(Met-),在5%葡萄糖与DL-蛋氨酸舔加量为75mg/l的条件下,能够积累3.5mg/ml L-苏氨酸。同样以MNNG诱变处理钝齿棒状杆菌C. crtenalum ASI.542,获得抗a一氨基一β一羟基戊酸(AHV)突变株1770林,其中6%菌株能够积累少量苏氨酸。选得LR—1458菌产L一苏氨酸(1mg/ml。 对该菌逐步诱变,得一株抗8mg/ml AHV及蛋氨酸缺陷型双重突变株(AHV,Mer) LRA-96,其L一苏氨酸产率与亲株比较有明显提高,达3.5mg/ml。连续再诱变并结合单菌落分离选育,得一突变株m一85(AHV,Met-),能在培养基中积累13mg/ml L-苏氨酸。试验表明,连续诱变处理是选育L一苏氨酸高产菌株有效手段之一。 相似文献
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旨在诱变选育L-异亮氨酸高产菌,并探索突变株最佳发酵条件。利用传统化学诱变结合常压室温等离子体生物诱变体系对实验室保藏的Brevibacterium flavum I-12进行逐级诱变,选育2-噻唑丙氨酸(2-TA)和磺胺胍(SG)高抗性和在琥珀酸平板上能快速生长的突变菌株。随后,在单因素实验的基础上,利用响应面设计优化出目的突变株摇瓶发酵培养基组分的最佳参数水平。结果显示,经过一系列诱变和筛选,成功选育出一株在40 g/L的2-TA和5 g/L的SG,且以琥珀酸为唯一碳源的培养基上快速生长突变株,命名为B. flavum TA-6,该菌株产酸达26.2±0.5 g/L,比出发菌株提高了44.75%,而副产物L-缬氨酸和L-亮氨酸积累量明显降低。经响应面法优化发酵条件后,突变株产酸可达27.8±0.5 g/L,比优化前提高了6.1%。通过传统化学诱变结合ARTP生物诱变体系,成功选育出一株杂酸降低的L-异亮氨酸高产菌TA-6,该菌株具有潜在生产应用价值。 相似文献
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积累PHB菌种隐藏嗜酸菌DX1-1的诱变改良 总被引:3,自引:1,他引:2
采用紫外线照射和放射性元素钴60辐射诱变方法,对分离纯化的一株可积累聚β-羟基丁酸酯(PHB)的Acidiphilium cryptumDX1-1进行了诱变改良,以获得PHB高产菌.结果显示钴60诱变最佳诱变剂量为100 Gy,紫外诱变的最佳剂量为15 W、30 cm、60 s,紫外诱变的效果比钴60诱变的效果好.诱变后筛选得到的一株菌UV60-3,PHB含量达到28.56 g/L,是原菌株的1.45倍,并且可稳定遗传.对菌株UV60-3积累PHB的碳氮比进行了探索,结果显示在碳源浓度60 g/L,氮源浓度30 g/L,C/N为3.76时PHB含量最高,PHB含量达到30.57 g/L. 相似文献
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FMP8902是从谷氨酸棒杆菌NO.17-3经人工诱变定向筛选而获得的一株苯丙氨酸产生菌。该菌株在5升罐的发酵中,以水解糖和糖蜜为主要原料,32±1℃,44小时,苯丙氨酸产量可达16.3mg/ml,转化率为12.9%。它的发酵副产物很少,遗传性状稳定。菌体为棒状至短杆状,无芽孢,革兰氏染色阳性,常见“V”形排列。FMP8902具有酪氨酸营养缺陷及四种芳香氨基酸结构类似物[DL-P氟苯丙氨酸、DL P-氯苯丙氨酸、P-氨基DL-苯丙氨酸、β-(2-噻吩)DL-丙氨酸]多重抗性,同时它能够在含利福平(5μg/ml)的培养基中正常生长。 相似文献
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用快中子法选育细菌脂肪酶高产菌株 总被引:4,自引:0,他引:4
研究了从土壤中筛选产脂肪酶的菌株,利用紫外线,快中子,快中子和磁场复合,γ射线,γ射线和磁场复合诱变,以酶活为筛子进行诱变育种,结果,出发菌酶活较低的一株得到了一株酶活为396.22U/mL的诱变株,此酶活比出发菌株高92倍,并发现比菌对紫外线和快中子比较敏感,而出发菌酶活较高的一株得到了酶活为424.60U/mL发酵液的诱变株,此酶活为出发菌株3.0倍,在此基础上,初步探讨了快中子,γ射线及磁场复合处理在产脂肪酶菌种诱变中的作用,并认为,在产脂肪酶菌株的诱变中快中子诱变更为有效。 相似文献
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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. 相似文献
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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
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. 相似文献
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JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
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. 相似文献
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肝癌中HBV和HCV基因和抗原的分布及意义 总被引:1,自引:0,他引:1
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 相似文献
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H.-R. GREGORIUS 《Biological journal of the Linnean Society. Linnean Society of London》1984,23(2-3):157-165
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. 相似文献
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. 相似文献