赤霉素产生菌的激光,化学复合诱变育种研究

采用激光和氯化锂复合诱变赤霉菌,对其产生的赤霉素中活性最高的ＧＡ３含量作为效价测定。结果表明与出发菌株相比,激光诱变,ＬｉＣｌ诱变,复合诱变效价分别提高为１１３．７％,４０．２％,１８９．６％。展示激光复合诱变是遗传育种的一种有效方法。     

激光诱变育种的研究概况

阐述了激光诱变育种机理的研究进展,激光诱变在农作物、畜牧兽医、工业微生物育种上的应用及已取得的成果,并介绍了激光诱变育种的一般操作过程和激光诱变育种的研究前景。     

激光在农作物遗传育种上的应用

本文论述了激光的作用原理包括光效应,热效应,压力效应和激光的应用包括小剂量激光对农作物的刺激作用,大剂量激光的诱变作用,其它诱变剂复合使用的诱变作用,并评述了激光在水稻,小麦,油菜、大麦、大豆及果树,蔬菜,桑等的研究进展,最后阐述了激光在农作物遗传育种上的应用前景。     

低功率He-Ne激光照射黑曲霉的方法与效应

目的:探索低功率He-Ne激光对柠檬酸生产菌黑曲霉诱变育种的简易方法。方法:应用带扩束镜的低功率He-Ne激光装置,在无菌条件下对柠檬酸生产菌黑曲霉的单孢子膜进行不同时间的垂直照射,无菌水洗脱,指示性平板筛选,液体培养,测定黑曲霉诱变菌株的柠檬酸产量。结果:不同时间的激光照射黑曲霉单孢子,其存活率与激光照射时间没有线性关系。激光照射6min,黑曲霉M2代产酸的正变率高达37.5%,而此时的存活率也高达40.0%。获得了黑曲霉柠檬酸产酸率提高了10%的突变菌株,为黑曲霉的遗传育种提供了材料。结论:这种方法便于在无菌条件下操作,保证了激光照射黑曲霉单孢子的均匀性,是一种简便易行的微生物诱变育种方法。     

植物空间诱变育种的现状与展望

本文在简要回顾植物空间诱变育种历史的基础上,论述了植物空间诱变育种的机理,植物在高真空、微重力、强辐射、交变磁场及其他因素的综合作用下产生变异和植物空间诱变育种效应以及突变性状的遗传;全面综述了空间诱变育种在中国作物新品种、特异优良种质材料的创新中取得的成就.最后对未来植物空间诱变育种的应用前景进行了展望,并指出空间诱变技术开创了植物育种的又一新途径.     

农用低功率He—Ne激光的诱变效应和育种

什么是低功率Ｈｅ－Ｎｅ激光;低功率Ｈｅ－Ｎｅ激光的诱变效应及其在育种上的应用;低功率Ｈｅ－Ｎｅ激光的诱变机制。     

阿魏菇多糖高产菌的离子束和激光复合诱变育种

目的:诱变筛选阿魏菇多糖高产菌,探索食用菌的离子束和激光复合诱变育种方法。方法:尝试用阿魏菇菌丝单细胞为靶材,以离子束注入和激光辐照为复合诱变手段,采用营养缺陷型筛选办法定性初筛,摇瓶发酵定量复筛。结果:通过离子束注入诱变,获得了2株菌丝体多糖产量分别达到551.80mg/L和659.46mg/L、较1号出发菌株提高了46.5%和75.2%的多糖高产菌PFPH-1和PFPH-2;在此基础上,以激光辐照为复合诱变手段,获得了1株菌丝体多糖产量达到762.50 mg/L、较出发菌株PFPH-2提高了15.63%的多糖高产菌PFPH-3。结论:离子束和激光复合诱变育种方法在改良阿魏菇多糖高产性状方面诱变功效显著。     

第六届全国激光生物学学术会议通知(第一号)

第六届全国激光生物学学术会议通知（第一号）经协商,第六届全国激光生物学学术会议定于１９９７年１１月召开,此次会议委托华侨大学主办。现将有关会议事项通知如下：一、会议地点：福建省泉州市国立华侨大学二、征文内容１．激光在植物、动物、微生物诱变遗传育种上的...     

药用微生物辐照诱变研究进展

常规的诱变育种方法主要是利用紫外线、激光、γ射线、中子等对微生物药物菌种进行辐照诱变,效果显著。离子束辐照微生物诱变育种在离子束生物学效应的研究中起步较晚,但其作为一种集物理诱变和化学诱变为一体的诱变育种新方法,将在辐照诱变育种中发挥重要作用。本文综述了近年来微生物药物研究与开发的动态,简要叙述微生物菌种选育的辐照诱变效应、作用机制及其在实践中的应用。     

工业微生物物理诱变育种技术的新进展

物理诱变技术是当今工业微生物育种中最重要、最有效的技术之一。传统的物理诱变技术主要有紫外线、X射线、γ射线诱变等,它们已在包括青霉素、"-淀粉酶等几乎所有的工业微生物菌种的诱变选育中发挥了巨大的作用。多数菌株在多次重复使用传统诱变源时往往出现抗性饱和的现象。太空环境、离子束、激光等是20世纪70～80年代逐渐兴起的新型诱变技术,因它们具有诱变谱广和在一定程度上能克服菌株对传统诱变源的抗性饱和等优点,而广受工业微生物育种工作者的欢迎。现就空间、离子束、激光等诱变育种技术的作用特点、诱变机理、应用及前景进行阐述。     

Genomic Background and Generation Time Influence Deleterious Mutation Rates in Daphnia

Understanding how genetic variation is generated and how selection shapes mutation rates over evolutionary time requires knowledge of the factors influencing mutation and its effects on quantitative traits. We explore the impact of two factors, genomic background and generation time, on deleterious mutation in Daphnia pulicaria, a cyclically parthenogenic aquatic microcrustacean, using parallel mutation-accumulation experiments. The deleterious mutational properties of life-history characters for individuals from two different populations, and for individuals maintained at two different generation times, were quantified and compared. Mutational properties varied between populations, especially for clutch size, suggesting that genomic background influences mutational properties for some characters. Generation time was found to have a greater effect on mutational properties, with higher per-generation deleterious mutation rates in lines with longer generation times. These results suggest that differences in genetic architecture among populations and species may be explained in part by demographic features that significantly influence generation time and therefore the rate of mutation.     

The genetics of adaptation: the roles of pleiotropy, stabilizing selection and drift in shaping the distribution of bidirectional fixed mutational effects

Pleiotropy allows for the deterministic fixation of bidirectional mutations: mutations with effects both in the direction of selection and opposite to selection for the same character. Mutations with deleterious effects on some characters can fix because of beneficial effects on other characters. This study analytically quantifies the expected frequency of mutations that fix with negative and positive effects on a character and the average size of a fixed effect on a character when a mutation pleiotropically affects from very few to many characters. The analysis allows for mutational distributions that vary in shape and provides a framework that would allow for varying the frequency at which mutations arise with deleterious and positive effects on characters. The results show that a large fraction of fixed mutations will have deleterious pleiotropic effects even when mutation affects as little as two characters and only directional selection is occurring, and, not surprisingly, as the degree of pleiotropy increases the frequency of fixed deleterious effects increases. As a point of comparison, we show how stabilizing selection and random genetic drift affect the bidirectional distribution of fixed mutational effects. The results are then applied to QTL studies that seek to find loci that contribute to phenotypic differences between populations or species. It is shown that QTL studies are biased against detecting chromosome regions that have deleterious pleiotropic effects on characters.     

移植物宿主反应的评价方法探讨

目的：研究移植物入机体后产生宿主反应的评价方法。方法：通过测量移植物植入机体后不同时期出现的结缔组织包囊的厚度变化，并进行统计学分析，从而探讨移植物的宿主反应特性的方法。结果：通过实验综合分析得出经表面处理的移植物的宿主反应特性较原为移植物有明显好转。结论：移植物植入机体后出现的结缔组织包囊的厚度变化，经统计学分析，可充分反应该移植物的宿主反应特性。通过本实验可较有效地、正确地评价该移植物的生物学特性。     

Associations between the 11-bp deletion in the myostatin gene and carcass quality in Angus-sired cattle

An 11-bp deletion in the bovine myostatin ( MSTN ) gene was identified as the causative mutation for the double-muscling phenotype in Belgian Blue and Asturiana cattle. More recently, this mutation was also identified in the South Devon breed of cattle, in which it has been found to be associated with a general increase in muscle mass. The present study found that the mutant allele was also segregating in a commercial population of Scottish Aberdeen Angus beef cattle. The mutation was found at a low frequency (0.04) with no animals homozygous for the mutation in the sample population (536 animals). The effects of this mutation on various carcass traits of economic interest were then tested. We found that the mutation significantly increased carcass weight, sirloin weight, hindquarter weight, muscle conformation score and eye muscle area, but had no effect on the fat traits.     

Mutational divergence of life-history traits in an obligate parthenogen.

Three lines of obligately parthenogenetic Daphnia were allowed to diverge for a 4-year period (approximately 150 generations) with mutation as the sole source of variability. Life-history traits and morphological characters were then surveyed for between-line differences. Significant divergence was found with respect to both number and size of offspring, with no difference in total offspring biomass. No significant differences were found in any of the other characters. These results confirm the hypothesis that purely asexual lines can accumulate enough polygenic variation via mutation to support potentially adaptive changes on a microevolutionary time scale.     

The balance between pleiotropic mutation and selection,when alleles have discrete effects

The theory of pleiotropic mutation and selection is investigated and developed for a large population of asexual organisms. Members of the population are subject to stabilising selection on Omega phenotypic characters, which each independently affect fitness. Pleiotropy is incorporated into the model by allowing each mutation to simultaneously affect all characters. To expose differences with continuous-allele models, the characters are taken to originate from discrete-effect alleles and thus have discrete genotypic effects. Each character can take the values nxDelta where n=0,+/-1,+/-2, em leader, and the splitting in character effects, Delta, is a parameter of the model. When the distribution of mutant effects is normally distributed around the parental value, and Delta is large, a "stepwise" model of mutation arises, where only adjacent trait effects are accessible from a single mutation. The present work is primarily concerned with the opposite limit, where Delta is small and many different trait effects are accessible from a single mutation.In contrast to what has been established for continuous-effect models, discrete-effect models do not yield a singular equilibrium distribution of genotypic effects for any value of Omega. Instead, for different values of Omega, the equilibrium frequencies of trait values have very different dependencies on Delta. For Omega=1 and 2, decreasing Delta broadens the width of the frequency distribution and hence increases the equilibrium level of polymorphism. For all sufficiently large values of Omega, however, decreasing Delta decreases the width of the frequency distribution and the equilibrium level of polymorphism. The connection with continuous trait models follows when the limit Delta-->0 is considered, and a singular probability density of trait values is obtained for all sufficiently large Omega.     

Life history and the male mutation bias

Abstract If DNA replication is a major cause of mutation, then those life-history characters, which are expected to affect the number of male germline cell divisions, should also affect the male to female mutation bias (a_m). We tested this hypothesis by comparing several clades of bird species, which show variation both in suitable life-history characters (generation time as measured by age at first breeding and sexual selection as measured by frequency of extrapair paternity) and in a_m, which was estimated by comparing Z-linked and W-linked substitution rates in gametologous introns. a_m differences between clades were found to positively covary with both generation time and sexual selection, as expected if DNA replication causes mutation. The effects of extrapair paternity frequency on a_m suggests that increased levels of sexual selection cause higher mutation rates, which offers an interesting solution to the paradox of the loss of genetic variance associated with strong directional sexual selection. We also used relative rate tests to examine whether the observed differences in a_m between clades were due to differences in W-linked or Z-linked substitution rates. In one case, a significant difference in a_m between two clades was shown to be due to W-linked rates and not Z-linked rates, a result that suggests that mutation rates are not determined by replication alone.     

Sexual selection,germline mutation rate and sperm competition

Background  

An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1) Increased sperm production associated with sperm competition may increase mutation rate. (2) Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection.     

Mutation and sexual selection: a test using barn swallows from Chernobyl

Abstract Secondary sexual characters have been hypothesized to be particularly susceptible to the deleterious effects of mutation because the expression of such characters is usually influenced by many more metabolic pathways than are ordinary morphological characters. We tested this hypothesis using the elevated mutation rates in the barn swallow ( Hirundo rustica ) of the Chernobyl region of Ukraine as a model system. A great deal is known about the relative importance of different characters for male mating success in this species. The importance of phenotypic characters for male mating success was quantified based on a long-term study of a Danish breeding population, by expressing phenotypic differences between mated and unmated males as the difference between log-transformed mean values. For field samples from Ukraine we likewise expressed the difference in male phenotype between individuals living in a relatively uncontaminated area and individuals from the Chernobyl region as the difference between log-transformed mean values. The standardized difference in male phenotype between the two regions in Ukraine for the 41 different characters was strongly positively correlated with the standardized difference in male phenotype between mated and unmated males from Denmark. The standardized difference in male phenotype between the two regions in Ukraine was significantly positively associated with sexual size dimorphism. However, the standardized difference in male phenotype between mated and unmated males was a much better predictor of standardized difference in male phenotype between the two regions in Ukraine than was the standardized difference in sexual size dimorphism, expressed as the difference between log-transformed mean values for males and females. These findings are consistent with the hypothesis that traits most important for sexual selection are particularly susceptible to the effects of deleterious mutations.     

细菌基因突变的策略及应用

细菌病仍然是目前危害人类和动物的重要疾病。细菌突变技术是重要的细菌学研究技术,包括传统的物理、化学、生物学等方法及现代的基因突变技术。基因突变技术是目前细菌学研究的重点,不同的基因突变技术采用的策略不同。细菌基因突变技术的开发和应用为细菌疫苗研制、细菌基因功能研究和基因治疗提供了新的技术手段。