耐氨基酸和氨基酸类似物水稻细胞系选择 Ⅰ.氨基酸和氨基酸类似物对水稻愈伤组织生长的影响

以单倍体和二倍体水稻愈伤组织为材料,在附加不同浓度的氨基酸或氨基酸类似物的筛选培养基上培养,测定其对愈伤组织的生长效应。结果表明:筛选抗性愈伤组织突变体的合适剂量为:1,000毫克/升的四氧赖氨酸(OL),2mM的AEC,2mM赖氨酸+1mM苏氨酸,10mM的色氨酸。     

水稻转基因种质IRBB13（PXa13:GFP）感病及育性突变体的筛选及鉴定

 【目的】建立简便高效的水稻突变体筛选体系,为克隆参与调控水稻xa13/ Xa13表达以及xa13/Xa13介导的抗/感病和花粉发育信号途径的基因奠定基础。【方法】利用EMS化学诱变携带显性Xa13启动子驱动绿色荧光蛋白（GFP）基因的水稻转基因种质IRBB13（PXa13:GFP）,构建突变群体,分3个时期进行突变体筛选：幼苗期筛选根和芽中绿色荧光减弱或消失的突变体、成株期筛选回复感病表型的突变体和孕穗期筛选育性下降的突变体。【结果】室内检测代M2突变体株系3 000个,筛到幼根和幼芽荧光消失的突变体14个,根部荧光正常而芽无荧光的突变体9个。田间试验种植突变体株系3 000个,成株期接种PXO99初步筛到回复感病表型的突变体株系25个。孕穗期筛选到育性下降且花药中绿色荧光消失的突变体株系7个,其中,包含1个回复感病的突变体株系。【结论】建立了简便高效的筛选水稻突变体筛选体系,结合GFP表达模式异常的突变体、回复感病突变体以及育性下降的突变体分析可判断xa13/Xa13参与的水稻抗/感病与花粉发育这2条信号网络途径并不是完全独立的,而是存在一定程度的交叉。     

植物抗氨基酸突变体研究进展

抗氨基酸突变体筛选是植物氨基酸品质改良的前提和基础。为进一步探讨抗氨基酸突变体的筛选方法及其有效利用,综述了植物抗氨基酸突变体研究现状、筛选方法及其取得的成就、存在的问题、应用前景,为植物的氨基酸品质改良提供参考。     

植物体细胞耐盐突变体的研究进展

植物体细胞耐盐突变体研究已经成为抗盐植物育种学研究的热点问题.综述了植物耐盐体细胞突变体筛选的试材确定、突变体筛选方法和突变体鉴定的研究现状,并指出植物耐盐突变体筛选还存在着变异类型复杂,变异方向难以控制,耐盐细胞系难以再生植株等缺陷.应加强高效稳定的植株再生体系建立;加强细胞悬浮培养技术研究,提高耐盐突变体筛选效率;提高耐盐目标性状的变异频率,减少非目的性状变异产生;从不同层面上加强耐盐突变体基础研究,提高突变体检测效果等方面研究,以提高植物体细胞耐盐突变体育种效果,更好地为实践和生产应用.参36     

水稻抗纹枯病突变体的离体筛选

以水稻成熟胚培养产生的愈伤组织和悬浮细胞为筛选材料,以广东省水稻纹枯病菌Rhizoctonia solaniKühn强致病力菌株GD-11和GD-118产生的粗毒素为选择压力,从水稻品种的选择、粗毒素致病力的鉴定、突变体的筛选方法、突变体的再生以及突变体再生植株对粗毒素的抗病性鉴定等方面展开研究,建立了水稻抗纹枯病突变体的筛选体系并获得了抗病突变体.筛选体系为:两步筛选法,即以粤香占的愈伤组织和悬浮细胞为筛选材料,以φ(粗毒素)为3.5%和4.0%分别作为第1、2步的处理浓度,每一步处理的时间为20 d;筛选出的突变体再生苗的病情指数为37.55,而原始型再生苗的病情指数为87.50,抗病效果达57.08%.     

植物抗性突变体离体筛选和鉴定研究进展

抗性突变体离体筛选技术已经成为一种新的育种技术,其获得的变异多属于单基因或少数基因变异,可以针对不同的需要改进植物个别性状。综述了抗性突变体的类型和抗性突变体离体筛选的途径、鉴定、研究近况及发展前景。     

利用巢式PCR方法筛选水稻OsIRT1突变体的研究

[目的]筛选得到水稻OsIRT1基因突变体。[方法]采用巢式PCR方法从水稻Tos17插入突变体库中筛选,共筛选近30000个单株。[结果]得到一个OsIRT1突变体单株。[结论]该突变体中的Tos17插入位点位于OsIRT1的内含子中。     

烟草抗马铃薯Y病毒(PVY)病突变体筛选与鉴定

[目的]筛选与鉴定烟草抗PVY病突变体,为寻找抗PVY的基因奠定基础.[方法]通过苗期对烟草突变材料进行PVY接种鉴定,肉眼对材料进行初步筛选,对筛选到的抗性材料进一步荧光定量鉴定,对筛选鉴定的抗性材料进行苗期鉴定及田间抗性鉴定.[结果]2011年筛选获得2个高抗PVY的突变体MZE2-15和MZE2-16,以及3个耐PVY突变体MZE2-70、MZE2-207及MZE2-228;2012年进一步筛选鉴定,突变体材料MZE2-407和MZE2-428感PVY,MZE2-16和2份MZE2-15突变体材料抗PVY.[结论]试验结果为控制烟草PVY病的危害提供了理论依据.     

利用离体培养技术筛选抗病突变体的研究进展

就离体培养筛选植物抗病突变体与常规育种相比所具有的优点,筛选的工作程序,国内外取得的成就,在细胞水平上筛选所用的诱变因子、方法及原始材料做了概述,并对离体培养筛选抗病突变体存在的问题及前景进行了阐述。     

组织培养技术筛选植物耐盐突变体的研究进展

在介绍耐盐突变体筛选技术的基础上,综述了利用组织培养技术筛选植物耐盐突变体的国内外研究现状,指出了存在的问题,并对其应用前景进行了展望。     

基因组偏好影响细菌直系同源蛋白质组成

从KEGG数据库中获得69种细菌的139组直系同源蛋白质序列,对它们的氨基酸组成及全基因组GC%含量与氨基酸组成关系进行各种分析。结果表明：核酸组成偏好对直系同源蛋白质的组成有极显著影响;不同功能类型的直系同源蛋白质氨基酸组成均受核酸GC%含量影响,氨基酸的组成受到选择压力与突变压力的双重影响。同时还指出,亲缘关系近的物种之间具有比全基因组GC%含量相近的物种之间更相似的直系同源蛋白质氨基酸组成。研究结果对于今后在各种研究中使用直系同源序列进行各种生物信息等相关分析,选择合适的物种材料具有重要的指导意义。     

氨基酸间的距离与蛋白质进化的随机模型

用遗传密码词典中61个密码作为链的状态,提出了一个氨基酸替代的马氏链模型。将20种氨基酸间首次通过时间作为突变距离与 Grantham(1974)的氨基酸间理化距离以及Dayhoff(1978)的相对替代概率做相关分析。结果表明,替代概率与理化距离的相关大大高于与突变距离间的相关,说明蛋白质进化过程中,是自然选择而非突变起着决定性作用。     

Amino acid replacements that compensate for a large polypeptide deletion in an enzyme

Deletion of more than 400 amino acids from the carboxyl terminus of an enzyme causes a severe reduction in catalytic activity. Selected point mutations within the residual protein partially reverse the effects of the missing segment. The selection can yield mutants with activities at least ten times as high as those of the starting polypeptides. One well-characterized mutation, a single amino acid replacement in the residual polypeptide, increases the catalytic activity of the polypeptide by a factor of 5. The results suggest substantial potential for design of protein elements to compensate for missing polypeptide sequences. They also may reflect that progenitors of large aminoacyl-tRNA (transfer RNA) synthetases--one of which was used in these studies--were themselves much smaller.     

Molecular evolution of the SARS coronavirus during the course of the SARS epidemic in China

Sixty-one SARS coronavirus genomic sequences derived from the early, middle, and late phases of the severe acute respiratory syndrome (SARS) epidemic were analyzed together with two viral sequences from palm civets. Genotypes characteristic of each phase were discovered, and the earliest genotypes were similar to the animal SARS-like coronaviruses. Major deletions were observed in the Orf8 region of the genome, both at the start and the end of the epidemic. The neutral mutation rate of the viral genome was constant but the amino acid substitution rate of the coding sequences slowed during the course of the epidemic. The spike protein showed the strongest initial responses to positive selection pressures, followed by subsequent purifying selection and eventual stabilization.     

A single amino acid mutation contributes to adaptive beach mouse color pattern

Natural populations of beach mice exhibit a characteristic color pattern, relative to their mainland conspecifics, driven by natural selection for crypsis. We identified a derived, charge-changing amino acid mutation in the melanocortin-1 receptor (Mc1r) in beach mice, which decreases receptor function. In genetic crosses, allelic variation at Mc1r explains 9.8% to 36.4% of the variation in seven pigmentation traits determining color pattern. The derived Mc1r allele is present in Florida's Gulf Coast beach mice but not in Atlantic coast mice with similar light coloration, suggesting that different molecular mechanisms are responsible for convergent phenotypic evolution. Here, we link a single mutation in the coding region of a pigmentation gene to adaptive quantitative variation in the wild.     

Classic selective sweeps were rare in recent human evolution

Efforts to identify the genetic basis of human adaptations from polymorphism data have sought footprints of "classic selective sweeps" (in which a beneficial mutation arises and rapidly fixes in the population).Yet it remains unknown whether this form of natural selection was common in our evolution. We examined the evidence for classic sweeps in resequencing data from 179 human genomes. As expected under a recurrent-sweep model, we found that diversity levels decrease near exons and conserved noncoding regions. In contrast to expectation, however, the trough in diversity around human-specific amino acid substitutions is no more pronounced than around synonymous substitutions. Moreover, relative to the genome background, amino acid and putative regulatory sites are not significantly enriched in alleles that are highly differentiated between populations. These findings indicate that classic sweeps were not a dominant mode of human adaptation over the past ~250,000 years.     

孕酮受体基因多态性及其与济宁青山羊产羔数关系

 【目的】寻找与产羔数相关的遗传标记,为山羊高繁殖力的标记辅助选择提供科学依据。【方法】设计15对引物,采用PCR-SSCP技术检测孕酮受体（progesterone receptor,PGR）基因全部9个外显子在济宁青山羊、波尔山羊、辽宁绒山羊和安哥拉山羊中的单核苷酸多态性,同时研究该基因对山羊繁殖力的影响。【结果】只有引物P1、P8与P9扩增片段具有多态性。对于P1扩增片段,济宁青山羊中检测到AA、AB和BB型,其余山羊中均检测到AA和AB型;测序表明BB与AA型相比有一处突变（31G→A）,并导致丙氨酸变为苏氨酸;BB基因型济宁青山羊产羔数最小二乘均值比AB基因型多0.52只（P＜0.05）,比AA基因型多0.98只（P＜0.001）,AB基因型济宁青山羊产羔数最小二乘均值比AA基因型多0.46只（P＜0.05）。对于P8扩增片段,济宁青山羊中只检测到CC型,波尔山羊中检测到CC和CD型,其余山羊中检测到CC、CD和DD型;测序表明DD型和CC型相比有一处突变（2810C→G）,未导致氨基酸改变。对于P9扩增片段,济宁青山羊和波尔山羊中检测到FF和FG型,其余山羊中检测到FF、FG和GG型;测序表明GG型和FF型相比有一处碱基突变（60128T→A）,未导致氨基酸改变;FF基因型济宁青山羊产羔数最小二乘均值比FG基因型多0.32只（P＞0.05）。【结论】本试验结果初步表明,PGR基因可能是控制济宁青山羊多羔性的一个主效基因或是与之存在紧密遗传连锁的一个标记。     

园艺植物化学诱变与抗性突变体筛选研究进展

从诱变材料和化学诱变剂的选择,诱变处理的方式、浓度和时间以及突变体的抗病、抗盐碱的定向筛选等方面总结了近年来园艺植物化学诱变与突变体筛选的研究进展,并对化学诱变技术的应用研究进行了展望。     

An Altered aroA Gene Product Confers Resistance to the Herbicide Glyphosate

The hypothesis that the herbicide glyphosate (N-phosphonomethylglycine) acts on plants and microorganisms by inhibiting synthesis of 5-enolpyruvyl-3-phosphoshikimate, a precursor to aromatic amino acids, was tested. Salmonella typhimurium was treated with ethyl methanesulfonate, and mutants mapping at the aroA locus, which encodes 5-enolpyruvyl-3-phosphoshikimate synthetase, were isolated by selection for glyphosate resistance. One of the mutants results in the synthesis of a 5-enolpyruvyl-3-phosphoshikimate synthetase that is resistant to inhibition by glyphosate. The mutant aroA gene and the corresponding wild-type allele were cloned. The mutation confers high resistance to glyphosate when introduced in Escherichia coli in the presence or absence of the wild-type aroA allele.     

五星黄鸡BMP15基因多态性分析

[目的]分析五星黄鸡的BMPl5基因多态性。[方法]以217只五星黄鸡L系母鸡为材料,采用全测序方法检测BMPl5基因的多态性及其与300日龄产蛋数的相关性。[结果]在BMPl5基因2个外显子中共检测到13个SNPs,在外显子1中检测到4个。其中C34T突变使亮氨酸变为苯丙氨酸;在外显子2中检测到9个,其中G540A突变使甘氨酸变为丝氨酸,其他位点为无义突变。G540A位点AA基因型比GA基因型产蛋数平均多16．7枚,差异显著（P〈O．05）;其余位点不同基因型产蛋数差异不显著。[结论]该研究为五星黄鸡高产蛋数的分子标记辅助选择提供了参考。