女性X连锁隐性鱼鳞病伴发Turner综合征遗传学探讨

本文在国内首次报道在X连锁隐性鱼鳞病家系中有一例女患者,其性染色体数目畸变,核型为45,X。我们认为,女患者在X连锁隐性遗传病方式中产生,除致病基因纯合原因外,还因一条X染色体丧失而致这种特殊方式。     

X 性连锁视网膜色素变性中的RP G R 基因的研究进展

视网膜色素变性是一组常见的遗传性致盲眼病,患病率约为1／3500。X染色体连锁遗传RP作为其中的一种类型,具有发病早,损害最为严重等特点。而在XLRP的相关基因中RPGR有着重要的意义。本文就RPGR的定位克隆、结构、功能及其突变谱予以综述,并对该基因的突变研究的临床意义作出了相关阐述。     

雌雄连锁基因的性别遗传

一、性别决定的研究概况美国遗传学家摩尔根在性别决定中指出,性染色体在生物界中比较普遍的类型有两种:XY型和ZW型.据此得出的结论是,出生的后代雌雄比值相等,但实际情况并非如此.例如有人做鳄类和人类胎儿的性别调查,均不符合1∶1规律.1976年研究哺乳类性别决定的美国免疫学家瓦赫特尔的H-Y抗原决定性别     

X连锁隐性遗传聋哑（deaf-mute）家系的遗传学特征分析

在进行中国人群的遗传性耳聋发病情况的调查中,发现了一个5代隔代遗传的聋哑家系（L021家系）。研究中调查家系成员64人,对其中的31人进行了系统的听力学检查,发现聋哑男性8位,听力表型为全聋及极重度聋,获得家系成员的血样31人份。家系图谱分析显示该家系为X连锁隐性遗传性耳聋家系,为先天性聋哑疾病分子病理机制的研究提供了模板。     

女性X连锁隐性鱼鳞病伴发Turner综合征遗传学探讨

本文在国内首次报道在x连锁隐性鱼鳞病家系中有一例女患者,其性染色体数目畸变,核型为45,x。我们认为,女患者在x连锁隐性遗传病方式中产生,除致病基因纯合原因外,还因一条x染色体丧失而致这种特殊方式。     

参与X染色体连锁智力障碍的表观遗传因子——PHF8研究进展

PHF8作为JmjC家族中的成员,通过对组蛋白赖氨酸的去甲基化酶活性来调节靶基因的转录。PHF8基因的一系列突变在X染色体连锁智力障碍（XLMR）患者中被发现。主要针对PHF8与XLMR发生的相关性以及PHF8的生化、生理功能进行阐述。     

人X染色体含有一个黑色素瘤抗原基因亚家族

肿瘤相关基因的研究是肿瘤基因形成学说的核心内容。肿瘤相关基因家族的研究则是其中的重点和难点,从4－6月孕龄人胎肝cDNA文库中克隆到一个黑色素瘤抗原基因亚家族,称为MAGE－D亚家族,其成员包括3个直系同源体（人MAGE－D1、大鼠SNERG－1和小鼠DLXIN－1）和2个旁系同源体（人MAGE－D和人KIAA1114）。该家族的3个人类成员均定位于染色体Xp11.21-p11.23,同时具有独特的基因组结构。分子进化树分析表明,该家族与已知MAGE－A、－B和－C3个亚家族之间具有明显的进化上分歧。该亚家族的发现为研究肿瘤相关基因新功能提供了重要线索。     

基因位置测定的理论与方法

生物的生理功能与基因在染色体上的位置有密切关系。本文依据基因所属连锁群或染色体和连锁群中基因之间的位置关系,记述不同的测定方法与基本原理,是遗传学教学改革后实验教学内容的一部分。体现出实验教学改革内容的科学性和先进性。     

X-连锁隐性遗传鱼鳞病的基因检测

问：我是一名女孩，我家系中有一个舅舅和我亲弟弟患病，已初步诊断为X-连锁隐性遗传鱼鳞病，在某医院做了大片断缺失型基因检测，但未检测到缺失。请问如何判断我是否也携带了致病基因？     

人基因组连锁分析和基因定位

连锁分析是确定基因之间连锁关系的统计学方法,是目前进行基因定位的重要手段,ＬＯＤ法是最为常用的有效的连锁分析的方法,本文连锁分析原理,方法和应用成果及前瞻等三方面进行了介绍。     

Influence of Gene Interaction on Complex Trait Variation with Multilocus Models

Although research effort is being expended into determining the importance of epistasis and epistatic variance for complex traits, there is considerable controversy about their importance. Here we undertake an analysis for quantitative traits utilizing a range of multilocus quantitative genetic models and gene frequency distributions, focusing on the potential magnitude of the epistatic variance. All the epistatic terms involving a particular locus appear in its average effect, with the number of two-locus interaction terms increasing in proportion to the square of the number of loci and that of third order as the cube and so on. Hence multilocus epistasis makes substantial contributions to the additive variance and does not, per se, lead to large increases in the nonadditive part of the genotypic variance. Even though this proportion can be high where epistasis is antagonistic to direct effects, it reduces with multiple loci. As the magnitude of the epistatic variance depends critically on the heterozygosity, for models where frequencies are widely dispersed, such as for selectively neutral mutations, contributions of epistatic variance are always small. Epistasis may be important in understanding the genetic architecture, for example, of function or human disease, but that does not imply that loci exhibiting it will contribute much genetic variance. Overall we conclude that theoretical predictions and experimental observations of low amounts of epistatic variance in outbred populations are concordant. It is not a likely source of missing heritability, for example, or major influence on predictions of rates of evolution.     

Spatial and Seasonal Variation in a Reservoir Sedimentary Microbial Community as Determined by Phospholipid Analysis

Sediment samples were collected monthly from Acton Lake, a eutrophic reservoir located in an agricultural region of southwestern Ohio, from three stations (River, Middle, and Dam) during the period May 1995 through January 1997. Sedimentary microbial biomass and community structures from these stations were studied using phospholipid analysis. At the River and Middle stations, the water column remained aerobic throughout the year, whereas the water overlying the Dam station sediments became anaerobic during summer stratification. Sedimentary microbial biomass at the River and Middle stations, as measured by the phospholipid phosphate (PLP) method, ranged from 225 to 450 nmol PLP g?1 d.w. (dry weight). Sedimentary microbial biomass at the Dam station was typically greater and ranged from 500 to 1,500 nmol PLP g?1 d.w. Principal component analysis of phospholipid fatty acid (PLFA) profiles indicated that the sedimentary microbial communities at all three stations displayed seasonal patterns of change. Among these patterns of change was a shift from aerobic microorganisms during times of cold water to anaerobic microorganisms during times of warm water. The Dam station differed from the River and Middle stations in that sediments from this station had disproportionately more polyenoic fatty acids, whereas sediments from the River and Middle stations had disproportionately more bacterial fatty acids. These data suggest that the Dam station may be a depositional zone for microeukaryotic phytoplankton produced in the overlying water column. These findings have implications for the understanding of carbon flux in reservoirs and preservation of organic matter in aquatic systems.     

遗传标记与数量性状基因间连锁关系的分析

本文讨论标记基因与数量性状主基因连锁关系的一般分析方法,包括重组值的估计和有关遗传假设的测验。并以我们水稻遗传试验中两个具有互补和重叠作用的卷叶基因和一个矮秆基因试验结果的分析为例作了较详细的示范。     

A Simple Analysis of an Inherited Trait

The authors describe a set of upper-elementary activities that focuses on how animals communicate. The activities describe procedures that students working in groups can use to investigate the topic of animal communication. An initial information sheet, resource list, and grading rubric are provided. The lesson plan was field-tested in an upper-elementary classroom.     

The Conservation Value of Peripheral Populations and a Relationship Between Quantitative Trait and Molecular Variation

The adaptive potential of populations and therefore their ability to cope with rapid environmental changes is a question of paramount fundamental and applied importance. However, what is still not clear is the effect of population position within the species range (i.e. core vs. edge) on population adaptive potential, and whether the adaptive potential can be predicted from extent of neutral molecular variation. In this study, we compared the extent and structure of neutral (SSR) and presumably adaptive quantitative trait genetic variation in populations of Triticum dicoccoides sampled at the species range core and two opposite edges, and related this information to multigenerational performance of plants experimentally introduced beyond the range edge. The plants from the species arid edge performed worse than plants from the more mesic core in extreme desert conditions. The core and edge populations did not differ in extent of SSR variation. In contrast to the neutral genetic variation, there was lower quantitative trait variation in the two edge as compared with the core population for many traits, and no trait in any edge population had higher variation than the core population or either of its habitats. Reduced variation in selectively important traits indicates a lower adaptive potential of the two edge as compared with the core population. Our results imply (1) that extent of variation in quantitative traits can predict plant performance in novel environments while extent of variation in molecular markers can not; and (2) caution in usage of peripheral populations in such conservation actions as relocation and creation of new populations. We also warn against usage of neutral molecular variation as a surrogate for selectively important quantitative variation in conservation decisions.     

Detection of Parent-of-Origin Specific Expression Quantitative Trait Loci by Cis-Association Analysis of Gene Expression in Trios

Parent-of-origin (PofO) effects, such as imprinting are a phenomenon in which homologous chromosomes exhibit differential gene expression and epigenetic modifications according to their parental origin. Such non-Mendelian inheritance patterns are generally ignored by conventional association studies, as these tests consider the maternal and paternal alleles as equivalent. To identify regulatory regions that show PofO effects on gene expression (imprinted expression Quantitative Trait Loci, ieQTLs), here we have developed a novel method in which we associate SNP genotypes of defined parental origin with gene expression levels. We applied this method to study 59 HapMap phase II parent-offspring trios. By analyzing mother/father/child trios, rules of Mendelian inheritance allowed the parental origin to be defined for ～95% of SNPs in each child. We used 680,475 informative SNPs and corresponding expression data for 92,167 probe sets from Affymetrix GeneChip Human Exon 1.0 ST arrays and performed four independent cis-association analyses with the expression level of RefSeq genes within 1 Mb using PLINK. Independent analyses of maternal and paternal genotypes identified two significant cis-ieQTLs (p<10(-7)) at which expression of genes SFT2D2 and SRRT associated exclusively with maternally inherited SNPs rs3753292 and rs6945374, respectively. 28 additional suggestive cis-associations with only maternal or paternal SNPs were found at a lower stringency threshold of p<10(-6), including associations with two known imprinted genes PEG10 and TRAPPC9, demonstrating the efficacy of our method. Furthermore, comparison of our method that utilizes independent analyses of maternal and paternal genotypes with the Likelihood Ratio Test (LRT) showed it to be more effective for detecting imprinting effects than the LRT. Our method represents a novel approach that can identify imprinted regulatory elements that control gene expression, suggesting novel PofO effects in the human genome.     

Quantitative Trait Loci Underlying Gene Product Variation: A Novel Perspective for Analyzing Regulation of Genome Expression

A methodology to dissect the genetic architecture of quantitative variation of numerous gene products simultaneously is proposed. For each individual of a segregating progeny, proteins extracted from a given organ are separated using two-dimensional electrophoresis, and their amounts are estimated with a computer-assisted system for spot quantification. Provided a complete genetic map is available, statistical procedures allow determination of the number, effects and chromosomal locations of factors controlling the amounts of individual proteins. This approach was applied to anonymous proteins of etiolated coleoptiles of maize, in an F(2) progeny between two distant lines. The genetic map included both restriction fragment length polymorphism and protein markers. Minimum estimates of one to five unlinked regulatory factors were found for 42 of the 72 proteins analyzed, with a large diversity of effects. Dominance and epistasis interactions were involved in the control of 38% and 14% of the 72 proteins, respectively. Such a methodology might help understanding the architecture of regulatory networks and the possible adaptive or phenotypic significance of the polymorphism of the genes involved.     

Gene Order of Encephalomyocarditis Virus as Determined by Studies with Pactamycin

Previous work has shown that translation of the encephalomyocarditis (EMC) viral ribonucleic acid (RNA) generates at least three primary products, polypeptides A, F, and C. The A and C polypeptides then undergo post-translational cleavages to complete the production of the stable viral polypeptides (delta, beta, gamma, alpha, G, I, F, H, and E). In this communication we show that A, F, and C are produced in equimolar amounts giving further support to the theory that the RNA of picornaviruses has only a single site for the initiation of protein synthesis. The biosynthesis of viral proteins in EMC virus-infected HeLa cells was studied in the presence of pactamycin at concentrations which preferentially inhibit the initiation of protein synthesis. The amount of each polypeptide formed during the residual period of protein synthesis observed after the addition of pactamycin was used as a criterion for ordering the genes on the viral RNA. The results obtained indicate that the primary gene products are ordered on the EMC viral RNA 5' --> 3' A-F-C and that the stable products are ordered delta-beta-gamma-alpha-G-I-F-H-E. Moreover, the intermediate chains B and epsilon map in the capsid region, whereas the intermediate chain D maps in the E region. This order is largely consistent with previously established relationships of the viral polypeptides and thus indicates that pactamycin is a valid tool for "genetic" mapping of polycistronic RNA molecules with single initiation sites.