浅谈家兔不同毛色的显隐性关系

浅谈家兔不同毛色的显隐性关系王明进（山东省高唐县第一中学２５２８００）随着养兔业的普遍开展，同学们时常提出有关家兔毛色遗传的问题。为配合教学，正确解答同学们提出的问题咱１９８２年春夭开始，对常见的白色免、青紫兰色、黑色兔、比利时免（野兔色）等进行杂交...     

MC1R基因多态性与豚鼠隐性黄毛色的相关性分析

豚鼠Cavia porcellus的隐性黄毛色表型是由编码黑素皮质激素受体1(MC1R)的extension基因座位的等位基因e控制。本研究对野生型和黄毛色豚鼠MC1R基因位点所在区域进行PCR扩增与测序发现,在黄毛色豚鼠中存在1个2 760 bp的基因组缺失,该缺失涵盖了MC1R基因的整个编码区。采用三引物扩增体系对豚鼠MC1R基因缺失突变进行群体基因分型,在随机选择的58只野生型个体中,36只为EE纯合子,22只为Ee杂合子,而31只黄毛色个体均为ee纯合子;在15只测交后代中,8只黄毛色个体均为ee纯合子,而7只野生型个体均为Ee杂合子。基因分型结果表明,MC1R基因2 760 bp的缺失与隐性黄毛色完全相关。本研究为进一步探究MC1R基因在哺乳动物毛色遗传机制中的作用以及豚鼠的分子标记辅助育种提供了理论依据。     

水稻白色中脉Oswm2的遗传分析与分子标记定位

从T-DNA突变体库中获得一份以中花11为遗传背景的白色中脉突变体。该突变体剑叶以下叶片的中下部中脉表现为白色, 白色中脉附近的叶色微黄, 并且伴随株高等农艺性状的改变, 暂时将其定名为Oswm2(Oryza sativa white midrib 2)。遗传分析表明该突变性状受一对隐性单基因控制, 以Oswm2和粳稻02428杂交的F2分离群体作为定位群体, 将OsWM2基因定位在水稻第7染色体的SSR标记RM21478和RM418之间, 遗传距离分别为8.7和15.9 cM。     

一种白背飞虱橙眼突变体

【目的】本实验的目的是研究白背飞虱Sogatella furcifera控制不同眼色的基因以及眼色突变对交配能力的潜在影响。【方法】在实验室中构建了一种新型的白背飞虱橙色复眼突变体,与此性状相关的基因型符号为org。利用包含3种基因型(+/+,+/org,org/org)的8组杂交组合实验来确定影响橙眼性状的遗传基础,并通过一项交配竞争实验来测试复眼眼色突变是否对白背飞虱交配能力有影响。【结果】该种橙眼突变体具有一对与野生型白背飞虱有明显区别的亮橙色复眼。在突变体白背飞虱发育阶段均出现了橙眼性状:卵期眼点(产卵3 d后出现),若虫复眼和任意性别翅型的成虫复眼。纯合子正常眼白背飞虱和橙眼白背飞虱之间的互交产生了F1正常眼颜色的后代。卡方检验表明交配后代并未倾向于特定的性别(α=0. 05,χ2c=0. 19～1. 53)。橙眼白背飞虱突变体的交配竞争能力显著弱于野生型白背飞虱。【结论】橙眼性状由常染色体隐性基因控制,且控制眼色的org基因对交配竞争能力有显著影响。     

绵羊黑色素合成相关基因的研究进展

毛色是一种可利用的遗传标记。在确定杂交组合、品种纯度和亲缘关系以及评价产品质量等方面均有一定的用途。哺乳动物毛色是由黑色素细胞产生的真黑素和褐黑素二者的分布和比例决定的。控制哺乳动物毛色色素的基因有很多,着重对黑色素合成相关基因酪氨酸酶基因(TYR)、黑素皮质激素受体1基因(MC1R)、鼠灰信号蛋白基因(Agouti)、酪氨酸酶相关蛋白1基因(TYRP1)的生物学功能及其遗传变异机制进行了综述。     

白色基因座(I)在中国地方猪种毛色遗传中的作用研究

通过利用PCR—RFLP和PCR—SSCP技术对中国地方猪种KIT基因内含子17、18的序列进行多态性分析。结果表明：内含子17上的替换突变(G→A)发生于毛色为白色的个体——白色五指山猪、大白猪、长白猪上,其基因型(AB型)频率分别为1、1和0．8;其他中国地方猪种的此基因型频率均为0。内含子18上的缺失突变(AGTT)也同样发生在上述3个猪种的白色个体中,其基因型(AA型)频率分别为1、1和0．93;而且同样在其他的地方品种中其基因型频率均为0。这充分证明KIT基因对于猪的白毛色有重要的调控作用,而且I基因座对于其他的经典遗传基因座有上位作用。另一方面,中国地方猪种荣昌猪虽然在表型上与引入猪种大白猪、长白猪相似(白毛色),但是在KIT基因上发生的突变完全不同,推测它们分别属于不同的毛色遗传体系。     

一种桔小实蝇蛹白化突变体的遗传分析

在实验室饲养野生型桔小实蝇Bactrocera dorsalis(Hendel)过程中发现了一种蛹色为白色的桔小实蝇突变品系。根据孟德尔遗传规律,设计野生型与突变型杂交(正交和反交)、F_1代与突变型回交、F_1代自交以及F_2代突变型自交等实验,对蛹白化突变性状的遗传规律进行研究。结果显示野生型与突变型杂交F_1代蛹色全部为野生型;F_2代野生型和突变型的性状分离比为2.98∶1,回交实验野生型与突变型性状分离比为1.19∶1;而突变体自交后代(F_3代)全部为突变体。结果表明桔小实蝇蛹色白化突变品系的遗传规律符合孟德尔遗传规律,属于常染色体上单基因控制的隐性遗传性状。     

第25届国际生物学奥林匹克竞赛试题 理论A-4

正遗传与进化31.野生型果蝇分别和3种隐性纯合突变体:b(黑体)、sc(亮红眼)和vg(残翅)进行正交。所获得的F1代果蝇分别与对应的纯合突变体回交,所得F2代表型和比例如下表所示:请指出下面的描述正确与否。A.将2个F2代,仅体色为黑体,其他性状正常的果蝇杂交将获得不同的翅膀表型B.b和vg基因位点的相对距离小于20 cM C.b和sc为杂合,vg为纯合的果蝇将产生等比例的4种不同基因型的配子D.如果vg和sc杂合个体进行杂交,所得后代     

小鼠毛色遗传的控制机制及其在遗传学教学中的应用

小鼠是最常用的哺乳动物模式生物,其毛色有白色、灰色、黄色、黑色等,是典型的孟德尔遗传性状。但在本科遗传学教学中,一般只在介绍隐性致死基因的时候才提到小鼠毛色遗传的例子。作者深入挖掘和整理了小鼠毛色遗传的分子机制,并把这个例子贯穿于讲解孟德尔遗传以及介绍分子遗传学的基因结构、基因功能、基因调控、基因互作、基因的表观遗传学修饰和数量性状遗传等,尝试用同一个案例贯穿本科遗传学教学,培养学生建立由表及里的系统分析能力,既凸显遗传学研究的前沿性和完整性,又吸引了学生的注意力,激发了学生的学习兴趣,收到了很好的教学效果。     

玉米卷叶突变体rol1的遗传分析与基因定位

叶型是作物理想株型育种的关键因素之一,发掘叶片发育相关基因对作物理想株型育种以及叶片发育的分子遗传机理研究具有重要意义。在玉米转座子Mutator活性系的杂交后代中,鉴定到一个玉米叶片卷曲的突变体,命名为rol1。突变体rol1在拔节期可明显观察到叶片内卷的表型,遗传分析表明,该卷叶表型受单隐性基因控制。将玉米骨干自交系B73和rol1杂交,构建遗传定位群体,利用BSR-Seq技术,对F2分离群体中的卷叶和展叶表型单株分别取样混池,进行转录组测序,将Rol1基因粗略地定位在玉米第5号染色体165~185 Mb区间内。进一步利用遗传分离群体中的卷叶表型单株缩小定位区间,将Rol1基因定位在SSR标记umc1822和umc1155之间,物理距离为5 Mb。本研究为Rol1基因的克隆和功能研究奠定了基础。     

Molecular genetics of the y locus in pepper: its relation to capsanthin-capsorubin synthase and to fruit color

Classical genetic studies have determined that the yellow fruit color in pepper is recessive to red in the locus y. We studied the relation of the y locus with the gene coding for capsanthin-capsorubin synthase (CCS) that synthesizes the red carotenoid pigments in the mature fruit. Cosegregation of y and CCS in populations derived from crosses between plants bearing red×white and red×yellow fruits indicated the correspondence of the two genes. We obtained indications for the occurrence of a deletion in the CCS gene in plants containing the recessive y allele. This deletion did not contain the distal 220 bp of the 3′ end of the gene. We used the CCS gene to determine the genotype of peppers with different fruit colors at the y locus. In BC₁ segregants from a red×white cross, the red and peach-fruited progenies had the wild-type allele at the CCS locus, while the orange, yellow and white-fruited progenies had the mutant allele. Screening orange-fruited cultivars with CCS as well as segregation analysis of CCS in an additional red×white cross indicated two possible genotypes of the orange fruit color in this locus. Received: 25 January 1999 / Accepted: 16 August 1999     

The genetics of coat colors in the mongolian gerbil (Meriones unguiculatus)

Genetic studies demonstrated three loci controlling coat colors in the Mongolian gerbil. F1 hybrids of white gerbils with red eyes and agouti gerbils with wild coat color had the agouti coat color. The segregating ratio of agouti and white in the F2 generation was 3:1. In the backcross (BC) generation (white x F1), the ratio of the agouti and white coat colors was 1:1. Next, inheritance of the agouti coat color was investigated. Matings between agouti and non-agouti (black) gerbils produced only agouti gerbils. In the F2 generation, the ratio of agouti to non-agouti (black) was 3:1. There was no distortion in the sex ratios within each coat color in the F1, F2 and BC generations. This indicated that the white coat color of gerbils is governed by an autosomal recessive gene which should be named the c allele of the c (albino) locus controlling pigmentation, and the agouti coat color is controlled by an autosomal dominant gene which might be named the A allele of the A (agouti) locus controlling pigmentation patterns in the hair. The occurrence of the black gerbil demonstrated clearly the existence of the b (brown) locus, and it clearly indicated that the coat colors of gerbils can basically be explained by a, b, and c loci as in mice and rats.     

Kit基因对白马被毛褪色的影响

马毛色是品种鉴定和个体识别的重要依据,也是制定育种方案时必须考虑的重要性状之一。因此,研究马被毛褪色已成为当今国际马毛色研究领域的重要内容,试图弄清导致马被毛褪色的真正机理。目前已经发现,许多马种被毛褪色表型个体中3号染色体上的kit基因存在不同的显著突变。研究结果表明马kit基因的正常表达与否与表皮中黑色素细胞及黑色素的形成密切相关,从而控制是否出现褪色表型。然而,研究证明在不同马种间褪色表型个体在该位点上出现的突变存在着较大的种间差异。具有被毛完全褪色表型的马群非常少见,只是偶尔见于有些马种,但在内蒙古锡林郭勒盟西乌珠穆沁旗生存着较大数量的被毛褪色表型个体,被称为蒙古白马。然而,造成其被毛褪色的机理还没有得到证实,有趣的是至今为止在蒙古白马kit基因的21个外显子中还没有发现任何典型突变。因此,文章对近些年国际上对马被毛褪色的分子研究进展做一比较系统的综合叙述,为蒙古白马毛色形成的机理研究奠定基础,为今后的马匹毛色研究及其育种工作提供有价值的参考依据。     

犬MC1R基因R306ter与毛色性状相关性研究

目的　分析犬MC1R基因中R30 6ter位点多态性与犬毛色表型的相关性 ,为遗传育种 ,培育出更加优良的实验用犬奠定基础。方法　采用PCR SSCP技术 ,对MC1R基因R30 6ter位点进行基因多态性检测 ,分析位点多态性与毛色性状之间的相关性 ,并对该位点进行克隆测序。结果　PCR SSCP分析结果表明 ,R30 6ter位点序列具有多态性 ,表现为C、D二个等位基因和CC、CD及DD三种基因型。对R30 6ter多态性片段克隆测序发现 ,MC1R基因在编码第 30 6位氨基酸的密码子处存在一个由CGA到TGA的终止突变。结论　经统计分析结果表明在杂种犬中MC1R基因多态性与毛色性状不存在显著的相关性 ,这可能是由于外科手术学教学用犬是杂种犬 ,其遗传背景不同所致。由于MC1R基因的R30 6ter位点内存在碱基变异 ,因此在杂种犬中表现出明显的PCR SSCP多态性     

Genetics of an Unstable White Mutant in Drosophila Simulans: Reversion, Suppression and Somatic Instability

A spontaneous white mutation, white-milky (wmky) of Drosophila simulans is moderately unstable and is associated with a 16-kb long DNA insertion into the white gene. wmky, which is an unstable mutation found in D. simulans, has been genetically analyzed. Among nine spontaneous, partial reversions toward wild type, five were white locus mutations. They are phenotypically different from each other and three show eye color sexual dimorphism indicating a failure of the dosage compensation mechanism. Two w locus mutations whose eye color appeared identical between males and females were also isolated. Of the other back-mutants, three were associated with a recessive suppressor of wmky and one was a semidominant suppressor. These suppressor loci are located on the third chromosome at map positions about 90 and 120, respectively. The suppressor mutations demonstrate specific effects on w locus mutations derived from wmky which lack in the gene dosage compensation. Somatic instability was detected at the frequency of 5.6 X 10(-4) in wmky flies heterozygous for the recessive suppressor and the frequency was increased 10-fold when the suppressor mutation was placed in a different genetic background.     

Marker-assisted genotype analysis of bulb colors in segregating populations of onions (Allium cepa)

Bulb color in onions (Allium cepa) is an important trait whose complex inheritance mechanism involves epistatic interactions among major color-related loci. Recent studies revealed that inactivation of dihydroflavonol 4-reductase (DFR) in the anthocyanin synthesis pathway was responsible for the color differences between yellow and red onions, and two recessive alleles of the anthocyanidin synthase (ANS) gene were responsible for a pink bulb color. Based on mutations in the recessive alleles of these two genes, PCR-based markers for allelic selection were developed. In this study, genotype analysis of onions from segregating populations was carried out using these PCR-based markers. Segregating populations were derived from the cross between yellow and red onions. Five yellow and thirteen pink bulbs from one segregating breeding line were genotyped for the two genes. Four pink bulbs were heterozygous for the DFR gene, which explains the continuous segregation of yellow and pink colors in this line. Most pink onions were homozygous recessive for the ANS gene, except for two heterozygotes. This finding indicated that the homozygous recessive ANS gene was primarily responsible for the pink color in this line. The two pink onions, heterozygous for the ANS gene, were also heterozygous for the DFR gene, which indicated that the pink color was produced by incomplete dominance of a red color gene over that of yellow. One pink line and six other segregating breeding lines were also analyzed. The genotyping results matched perfectly with phenotypic color segregation.     

A deletion in exon 9 of the LIPH gene is responsible for the rex hair coat phenotype in rabbits (Oryctolagus cuniculus)

The fur of common rabbits is constituted of 3 types of hair differing in length and diameter while that of rex animals is essentially made up of amazingly soft down-hair. Rex short hair coat phenotypes in rabbits were shown to be controlled by three distinct loci. We focused on the "r1" mutation which segregates at a simple autosomal-recessive locus in our rabbit strains. A positional candidate gene approach was used to identify the rex gene and the corresponding mutation. The gene was primo-localized within a 40 cM region on rabbit chromosome 14 by genome scanning families of 187 rabbits in an experimental mating scheme. Then, fine mapping refined the region to 0.5 cM (Z = 78) by genotyping an additional 359 offspring for 94 microsatellites present or newly generated within the first defined interval. Comparative mapping pointed out a candidate gene in this 700 kb region, namely LIPH (Lipase Member H). In humans, several mutations in this major gene cause alopecia, hair loss phenotypes. The rabbit gene structure was established and a deletion of a single nucleotide was found in LIPH exon 9 of rex rabbits (1362delA). This mutation results in a frameshift and introduces a premature stop codon potentially shortening the protein by 19 amino acids. The association between this deletion and the rex phenotype was complete, as determined by its presence in our rabbit families and among a panel of 60 rex and its absence in all 60 non-rex rabbits. This strongly suggests that this deletion, in a homozygous state, is responsible for the rex phenotype in rabbits.     

Two recessive rex coat mutants in the guinea pig

Two rex type coat mutants of the guinea pig were found to display monogenic recessive inheritance at independent loci. The mutant alleles were designated rex (rx) and waved (wv). Both genes modify the normal smooth coat to a more upright, somewhat unkempt pelage. Macroscopically, the two rexes are scarcely distinguishable. Microscopically, however, small differences are apparent in the degree of coat modification. The hairs of rex show a greater curvature than normal and have irregular secondary bends and twists and variable diameter; so do those of waved, but to a lesser degree. The vibrissae of rex are curved or bent and may break off; those of waved are a mixture of straight, curved, and bent hairs.     

Recessive yellow in the Mongolian gerbil (Meriones unguiculatus)

A new autosomal recessive coat color mutant in the Mongolian gerbil (Meriones unguiculatus) is described: recessive yellow. On the dorsal side the mutant has a rich yellow to ginger color. Ventrally it shows the typical creamy white belly of a wild-type Mongolian gerbil. The dorsal yellow hairs have short black tips, and a light olive green base. A clear demarcation line between dorsal and ventral color is present. Crosses between recessive yellow animals and multiple homozygous recessive tester animals (a/a; c^chm/c^chm; g/g; p/p) resulted only in animals of an agouti (wild-type) phenotype, showing that the new allele is not allelic with any of the known coat color mutations in the Mongolian gerbil. Molecular studies showed that the new mutant is caused by a missence mutation at the extension (E) locus. On a non-agouti background (a/a; e/e) mutant animals look like a dark wild-type agouti. In contrast to wild-type agouti it shows yellow pigmentation and dark ticking at the ventral side, resulting in the absence of a demarcation line. Since black pigment is present in both the agouti and non-agouti variant (A/A; e/e and a/a; e/e), we conclude that recessive yellow in the Mongolian gerbil is non-epistatic to agouti. Additionally we describe a second mutation at the same locus leading to a similar phenotype, however without black pigment and diminishing yellow pigment during life. Fertility and viability of both new mutants are within normal range. The extension (E) gene is known to encode the melanocortin 1 receptor (MC1R). Interestingly, this is the only gene that is known to account for substantial variation in skin and hair color in humans. Many different mutations are known of which some are associated with higher skin cancer incidence.