负调节基因nsdA在链霉菌中同源性及激活沉默抗生素合成基因簇的研究

nsdA基因是在天蓝色链霉菌中发现的抗生素合成负调控基因。以nsdA基因片段为探针,通过Southern杂交发现nsdA存在于多种链霉菌中。根据天蓝色链霉菌和阿维链霉菌的nsdA序列设计PCR引物,扩增多种链霉菌中nsdA基因并测序。发现在不同链霉菌中nsdA基因的相似性高达77%~100%。其中变铅青链霉菌与天蓝色链霉菌A3(2)的nsdA序列100%一致。变铅青链霉菌通常不合成放线紫红素,中断nsdA获得的突变菌株WQ2能够合成放线紫红素;在WQ2中重新引入野生型nsdA,又失去产抗生素能力。表明nsdA的中断可以激活变铅青链霉菌中沉默的放线紫红素生物合成基因簇的表达;nsdA的广泛存在及其序列高度保守则提示可以尝试用于这些菌种的抗生素高产育种。     

海洋链霉菌次级代谢产物研究进展

链霉菌作为最高等的放线菌,广泛分布于多种生态环境中,具有复杂而独特的形态分化周期和强大的次级代谢能力。链霉菌的次级代谢产物具有抗感染、抗肿瘤、抗炎抗氧化、免疫调节等生物活性,是天然活性产物的主要来源之一。近年来随着对海洋资源的开发,许多新型的海洋链霉菌及其丰富的次级代谢产物被发现。从海洋链霉菌的生物活性物质、育种和发酵培养3个方面综述了海洋链霉菌次级代谢产物的研究进展,以期为缩短海洋链霉菌的发酵周期,提高次级代谢产物产量活性以及开发新型的海洋药物等提供参考和借鉴。     

阿维菌素的生物合成及代谢工程研究进展

阿维菌素(avermectin)是由除虫链霉菌(Streptomycesavermitilis)产生的一种具有杀虫活性的大环内酯类抗生素,在农业和畜牧业中应用广泛。本文综述了有关除虫链霉菌基因组序列分析、阿维菌素的生物合成以及阿维菌素育种和代谢工程的研究进展。     

CRISPR/Cas9基因组编辑技术及其在链霉菌中的应用

链霉菌(Streptomyces)以产生多种抗生素而著称,长期以来都是生命科学与医学、药学及工业领域的研究热点。然而,链霉菌的遗传操作十分困难,传统的基因编辑手段因效率低、实验周期长及操作步骤繁琐等原因正逐渐被素有"魔剪"之称的CRISPR(Clustered regularly interspaced short palindromic repeats)/Cas9(CRISPR-associated protein 9)系统所替代。该技术可以对基因组特定位点进行靶向编辑,包括缺失(Indel)、修复(Repair)和替换(Replacement)等。通过比较目前在链霉菌中基因编辑手段,总结出CRISPR/Cas9系统在链霉菌应用方面具有操作简单、效率高、成本低、实验周期短,以及能够同时敲除多个基因等优势,并综述了该系统在链霉菌中的应用,以及汇总了CRISPR/Cas9工具箱的靶向空间,最后针对该系统在链霉菌定向育种方面及合成新的抗生素方面进行展望,以期为相关领域的工作提供参考。     

负调节基因nsdA在链霉菌中同源性及激活沉默抗生素合成基因簇的研究

nsdA基因是在天蓝色链霉菌中发现的抗生素合成负调控基因。以nsdA基因片段为探针,通过Southern杂交发现nsdA存在于多种链霉菌中。根据天蓝色链霉菌和阿维链霉菌的nsdA序列设计PCR引物,扩增多种链霉菌中nsdA基因并测序。发现在不同链霉菌中nsdA基因的相似性高达77%～100%。其中变铅青链霉菌与天蓝色链霉菌A3(2)的nsdA序列100%一致。变铅青链霉菌通常不合成放线紫红素,中断nsdA获得的突变菌株WQ2能够合成放线紫红素;在WQ2中重新引入野生型nsdA,又失去产抗生素能力。表明nsdA的中断可以激活变铅青链霉菌中沉默的放线紫红素生物合成基因簇的表达;nsdA的广泛存在及其序列高度保守则提示可以尝试用于这些菌种的抗生素高产育种。     

基因组重排与传统育种相结合选育大观霉素高产菌株

以壮观链霉菌(Streptomyces spectabilis)为研究对象,采用基因组重排技术与传统诱变育种相结合的方法选育大观霉素的高产菌株.通过原生质体紫外诱变获得壮观链霉菌突变体群体,高产突变菌株间进行两轮的基因组重排,筛选的高产菌株用NTG诱变得新霉素和链霉素的抗性突变菌株,抗性突变菌株间进行两轮基因组重排,从...     

天蓝色链霉菌中抗生素合成相关双组分调控系统AfsQ1/Q2上游信号传导机制的研究

链霉菌是重要的工业微生物,能够合成众多具有生物活性的次级代谢产物,如抗生素、抗肿瘤药物以及免疫抑制剂等.次级代谢产物的合成受到多层次严格调控,深入开展相关机制研究将对工业菌株的高效育种提供重要理论指导.链霉菌中存在的两类关键信号传导系统,包括双组分系统(two-component system,TCS)和胞质外功能σ因...     

南昌链霉菌的微波诱变

以微波对南昌链霉菌进行了微波育种,获得梅岭霉素杀虫剂生产能力高于出发菌株73％的W4-311。该菌株经多次传代,遗传性状保持稳定。     

大肠杆菌-链霉菌高效接合载体的构建及其应用

以链霉菌质粒SCP2^*的衍生质粒pHJL400为基础,构建了能够在大肠杆菌到链霉菌之间进行高效接合转移的质粒DGH112。pGH112含有在大肠杆菌和链霉菌中复制起始位点,以及分别在大肠杆菌和链霉菌中进行筛选的抗性标记。用pGH112转化Escherichia coli ET12567(pUZ8002)后,与天蓝链霉菌(Streptomyces coelicolor A3(2))、除虫链霉菌(Streptomyces avermitilis)、变铅青链霉菌(Streptomyces lividans TK54)、毒三素链霉菌(Streptomyces toxytricini NRRL15443)、委内瑞拉链霉菌(Streptomyces．vertezuelae ISP5230)和红色糖多孢菌(Saccharopolypora erythraea)进行接合,发现本构建的pGH112与pKC1139相比,接合转移效率较高,稳定性好,而且宿主范围较广。把组成型启动子ermE^*与绿色荧光蛋白基因(gfp)克隆到本构建的pGH112,通过接合转移到链霉菌中,gfp获得表达,证明其可以用作基因接合转移的有效工具载体,这为研究链霉菌的基因功能创造了有利条件。     

黑暗链霉菌DNA转移系统的建立

研究了黑暗链霉菌的基因转移系统,探索了通过PEG介导的原生质体转化、接合转移向黑暗链霉菌中转入外源DNA的可能性。多次尝试用质粒pIJ702转化黑暗链霉菌9904原生质体均未成功。对原生质体进行“热处理”后转化、利用单链DNA转化等都不能将质粒导入黑暗链霉菌中,表明黑暗链霉菌对外源DNA有很强的限制修饰作用。利用接合转移将具有oriT的大肠杆菌链霉菌穿梭质粒pHZ132转入大肠杆菌ET12567(pUZ8002)中,获得供体菌ET12567(pUZ8002,pHZ132)。将供体菌与预萌发的黑暗链霉菌9904的孢子进行接合转移,成功地将pHZ132转入黑暗链霉菌9904中。质粒pHZ132经黑暗链霉菌自身修饰后也可转入黑暗链霉菌9904菌株的原生质体中,转化率约为103/μg DNA(pHZ132)。     

基因敲除在工业微生物育种方面的应用

微生物育种技术的发展先后经历了自然选育、诱变育种、杂交育种、代谢控制育种和基因工程育种5个阶段,其中基因工程育种技术中的基因敲除技术具有定位性强、经修饰和改造的基因能够随染色体DNA的复制而稳定地复制的特点,使人们可以有目的地去改造生物的遗传物质,从而达到微生物育种的目的,受到人们的广泛关注。就基因敲除技术的几种主要方法及其在改良工业生产菌株中的应用作简要介绍。     

Development and application of biological technologies in fish genetic breeding

Fish genetic breeding is a process that remolds heritable traits to obtain neotype and improved varieties.For the purpose of genetic improvement,researchers can select for desirable genetic traits,integrate a suite of traits from different donors,or alter the innate genetic traits of a species.These improved varieties have,in many cases,facilitated the development of the aquaculture industry by lowering costs and increasing both quality and yield.In this review,we present the pertinent literatures and summarize the biological bases and application of selection breeding technologies(containing traditional selective breeding,molecular marker-assisted breeding,genome-wide selective breeding and breeding by controlling single-sex groups),integration breeding technologies(containing cross breeding,nuclear transplantation,germline stem cells and germ cells transplantation,artificial gynogenesis,artificial androgenesis and polyploid breeding)and modification breeding technologies(represented by transgenic breeding)in fish genetic breeding.Additionally,we discuss the progress our laboratory has made in the field of chromosomal ploidy breeding of fish,including distant hybridization,gynogenesis,and androgenesis.Finally,we systematically summarize the research status and known problems associated with each technology.     

基因工程在农作物育种上研发应用新进展

以文献调研结果为依据,概述了基因工程的基本概念与基本模式,外源DNA导入的方式与表达的条件;应用基因工程培育优质、高产、抗病、抗虫、抗除草剂与抗逆性强农作物品种的进展;预测并展望了基因工程在实现农业现代化目标中的作用、开发应用重点与前景。     

Fine-scale genetic structure and its consequence in breeding aggregations of a passerine bird

The pattern of fine-scale genetic structure in a population may reflect current biological processes of the species, such as natal dispersal, the breeding system and demography. We investigated the spatial distribution of nests and fine-scale genetic structure during two breeding seasons in a population of a weakly territorial, flock-living passerine bird, the vinous-throated parrotbill, Paradoxornis webbianus . Nest distribution was clustered. There were two peaks of egg laying within each breeding season, and spatial clustering of nests was more extreme during the second peak after controlling for breeding density. The patterns of genetic structure during the breeding season varied with parental sex and season. Genetic structure occurred during the second laying peak: males breeding within 200 m of one another at this time were significantly more closely related than males breeding farther apart. However, no apparent genetic structure was detected in males during the first laying peak or among females in either laying peak. These results reveal male-oriented kin affiliation during part of the breeding season in this species. Furthermore, juvenile recruitment into the winter flocks was positively related to this increased relatedness among males via kin affiliation. This study implies that fine-scale genetic structure during the breeding season could be a factor determining individual fitness and may play an important role in our understanding of the evolution of social systems.     

微藻育种与培养研究概况

微藻类的天然产物具有广泛的遗传变异和潜在的经济价值,但是这些天然产物的获取还依赖于品种的改良和适宜的培养条件。本文概括性地论述了微藻的遗传育种和优化培养。它包括微藻类的遗传多样性、选择育种、诱变育种、细胞融合、基因工程以及固定化培养和生物反应器的应用。这些生物技术为微藻类的利用开辟了广阔的前景。     

Allelic reduction and genetic shift in the Canadian hard red spring wheat germplasm released from 1845 to 2004

Analysis of genetic diversity changes in existing gene pools of cultivated crops is important for understanding the impact of plant breeding on crop genetic diversity and developing effective indicators for genetic diversity of cultivated plants. The objective of this study was to assess genetic diversity changes in 75 Canadian hard red wheat (Triticum aestivum L.) cultivars released from 1845 to 2004 using 31 simple sequence repeats (SSRs) markers. A total of 267 SSR alleles were detected, and their allelic frequencies ranged from 0.01 to 0.97, with an average of 0.14. Significant allelic reduction was observed at only four SSR loci for the cultivars released from 1970 onwards. However, 51 alleles (about 19%) present in pre-1910 cultivars were undetected in cultivars released after 1990 and were spread over 27 SSR loci. The proportion of SSR variation accounted for by six breeding periods was 12.5%, by four ancestral families, 16.5%, and by eight breeding programs, 8.4%. The average genetic diversity measured by three different band-sharing methods did not change significantly among cultivars released from different breeding periods, breeding programs, and ancestral families. However, genetic shift was obvious in the cultivars released over the six breeding periods, reflecting well the various breeding efforts over years. These results clearly show the allelic reduction and genetic shift in the Canadian hard red spring wheat germplasm released over time. Consequently, more effort needs to be made to broaden the wheat breeding base and conserve wheat germplasm.     

植物的繁育系统、遗传结构和遗传多样性保护

达尔文和最早的群体遗传学理论,都认为繁育系统对生物的遗传多样性和进化起重要作用。本文首先介绍用蛋白质电泳检测植物繁育系统的优点,然后讨论中外学者的实验结果,表明在植物众多特征中,如生活型、是有性繁殖还是无性繁殖等都能影响群体遗传结构,但最显著的是繁育系统和群体遗传分化两者间的关系。因此我们能从植物的繁育系统推测群体遗传结构,进而提出监测遗传多样性的取样策略,这对就地保护和移地保护都是十分重要的     

Genetic parameters for agronomic characteristics. I. Early and intermediate breeding populations of true potato seed

The original variation in the source population as well as the selection method may influence the genetic variation in further cycles of genetic improvement. Therefore, the objectives of this research were to determine genetic parameters (variance components and heritability) in source and intermediate stages of a true potato seed (TPS) breeding population and to calculate the genetic and phenotypic correlations in this breeding material developed by the Centro Internacional de la Papa (CIP). The intermediate stage was derived from a source population adapted to the warm lowland tropics plus introduction of exotic germplasm from North America and Europe. Non-additive genetic variation was almost nil for plant survival, tuber yield and tuber shape uniformity in both stages of the breeding population and no quantitative genetic variation for uniformity of tuber color was observed in both source and intermediate breeding materials. Heritability was higher in the intermediate stage than in the source population for plant survival (0.86 vs 0.66), tuber yield (0.30 vs 0.14) and tuber shape (0.77 vs 0.51), but it was the reverse for tuber uniformity (0.11 vs 0.72). These results suggest that potato breeders at CIP were able to keep enough genetic variation for most important characteristics for potato production from true seed in their intermediate breeding materials by adding new sources of variation to the original breeding population. Additive genetic and phenotypic correlations were significant and positive between plant vigor after transplanting and tuber yield, and tuber shape and tuber uniformity, which suggest that high yielding offspring result from early vigorous growth, and that tuber uniformity could depend on tuber shape uniformity in this breeding material.     

华南鲤选育群体不同世代遗传多样性与遗传结构的微卫星分析

为了解人工选育对华南鲤(Cyprinus carpio rubrofuscus)选育群体遗传结构的影响, 采用微卫星技术分析了华南鲤4个连续选育世代(F₁、F₂、F₃和F₄)的遗传多样性和遗传结构。结果显示:在4个选育群体中, 16对微卫星引物共扩增得到99个等位基因, 每个微卫星座位检测到的等位基因数为3—10个, 平均为6.1875个。随着人工连续选育的进行, F₁到F₄的平均等位基因数(N_a)从5.6875下降到4.6755, 平均观测杂合度(H_o)从0.7943下降到0.7135, 平均多态信息含量(PIC)从0.6577下降到0.5834。F₁与其后各代的遗传距离逐代增加(从0.1486上升到0.2181), 遗传相似系数逐代减小(从0.8619下降到0.8041), 而相邻世代间的遗传分化指数(F_st)逐代变小(F₁与F₂为0.062, F₂与F₃为0.058, F₃与F₄则为0.051), 遗传相似性逐步升高。世代间F_st值配对比较结果显示4个世代间的遗传分化处于中等水平, 表明人工选育已对华南鲤选育群体的遗传结构产生了影响。实验结果表明, 华南鲤经过4代选育后, 虽然遗传杂合度和遗传多样性存在下降的现象, 但遗传多样性水平依然较高, 还具有进一步选育的潜力。研究结果为下一步制定华南鲤新品种选育计划提供基础遗传数据。