Coat color genetics of Peromyscus. I. Ashiness, an age-dependent coat color mutation in the deer mouse

Ashy deer mice (Peromyscus maniculatus) were first discovered about 1960 in a wild population from Oregon. Although indistinguishable from the wild type at weaning, ashy deer mice become progressively grayer with subsequent molts. The trait is inherited as an autosomal recessive and the symbol ahy is assigned for the locus. The trait is distinctly manifest by 6 months of age, at which time homozygotes have white hairs on the muzzle and at the base of the tail. The amount of white gradually increases with age, but development varies greatly among animals. Some become virtually all white by 18 months. Implants of melanocyte-stimulating hormone induced production of pigment in depigmented portions of the coat, indicating that viable melanocytes were present. The ashy deer mouse model may be useful for further study of melanocyte function.     

Tawny: a novel light coat color mutation found in a wild population of Mus musculus molossinus, a new allele at the melanocortin 1 receptor (Mc1r) locus.

We found a new coat color mutant in a population of Japanese wild mice (Mus musculus molossinus) and called the trait tawny. The tawny mutant is characterized by a light yellowish brown coat color. The tawny hair has a so-called agouti pattern, but the yellow band is greatly lengthened. There are no differences between the tawny and wildtype hairs in size and the number of melanosomes. Genetic analyses revealed that the tawny trait is an autosomal recessive and its gene is located in the distal region on Chromosome 8 between the microsatellite markers D8Mit87 and D8Mit122. An allelism test indicated the tawny mutant gene to be a new allele at the Mc1r locus and dominant to the recessive yellow (Mc1re). The proposed gene symbol for the tawny is Mc1rtaw.     

Coat color determination by miR-137 mediated down-regulation of microphthalmia-associated transcription factor in a mouse model

Coat color is a key economic trait in wool-producing species. Color development and pigmentation are controlled by complex mechanisms in animals. Here, we report the first production of an altered coat color by overexpression of miR-137 in transgenic mice. Transgenic mice overexpressing miR-137 developed a range of coat color changes from dark black to light color. Molecular analyses of the transgenic mice showed decreased expression of the major target gene termed MITF and its downstream genes, including TYR, TYRP1, and TYRP2. We also showed that melanogenesis altered by miR-137 is distinct from that affected by UV radiation in transgenic mice. Our study provides the first mouse model for the study of coat color controlled by miRNAs in animals and may have important applications in wool production.     

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.     

Genetic determinants of sable and umbrous coat color phenotypes in mice

The dorsal fur in yellow F1 mice (F1-Ay) between C3H/HeJ and C57BL/6J-Ay is darker than that in C57BL/6J-Ay. Moreover, yellow F2 mice (F2-Ay) exhibit a wide spectrum of coat color phenotypes in terms of lightness and darkness. Quantitative trait locus (QTL) analysis on F2-Ay identified three significant modifier loci that accounted for darkening of the coat color on chromosomes 1 (Dmyaq1 and Dmyaq2) and 15 (Dmyaq3), and the C3H/HeJ allele at these loci increased the darkness. Because agouti F2 mice (F2-A) also exhibited a spectrum of coat color phenotypes, the question of whether these QTLs had any effects on F2-A was examined. Dmyaq1 and Dmyaq2 were shown to increase the darkness in F2-A, whereas Dmyaq3 did not. The results showed that Dmyaq1-Dmyaq3 were parts of determinants responsible for the sable (darker modification of yellow) coat color phenotype, and that Dmyaq1 and Dmyaq2 were parts of determinants responsible for the umbrous (darker modification of agouti) coat color phenotype. It is, thus, demonstrated that both the sable and the umbrous phenotypes resulted from multigenic contributions, and that they shared genetic bases, as had been implied for several decades.     

Ragged--a new rexoid mutant rat with large sebaceous gland

A new hair defected mutant rat was established. This mutant was covered with ragged hair since about 10 days of age, then transiently lost most of hair in the back at approximately 5 weeks of age and re-covered with ragged hair thereafter. Thickened eyerids occurred since about 3 weeks of age. Histological examination revealed enlarged sebaceous glands with greater number of sebaceous cells in the back skin. The oil stained skin samples showed normal sebaceous transformation and pilosebaceous canal. Genetical analysis showed that the ragged hair character was a single recessive trait and indicated that this single recessive gene was not linked with the coat color genes, non-agouti (a), albino (c) and hooded (h). From the present data and previous reports, we recommended this single recessive gene is a new rexoid mutation thereby we termed this gene "Ragged (rg)".     

Recessive black is allelic to the yellow plumage locus in Japanese quail and associated with a frameshift deletion in the ASIP gene

The recessive black plumage mutation in the Japanese quail (Coturnix japonica) is controlled by an autosomal recessive gene (rb) and displays a blackish-brown phenotype in the recessive homozygous state (rb/rb). A similar black coat color phenotype in nonagouti mice is caused by an autosomal recessive mutation at the agouti locus. An allelism test showed that wild type and mutations for yellow, fawn-2, and recessive black in Japanese quail were multiple alleles (*N, *Y, *F2, and *RB) at the same locus Y and that the dominance relationship was Y*F2 > Y*Y > Y*N > Y*RB. A deletion of 8 bases was found in the ASIP gene in the Y*RB allele, causing a frameshift that changed the last six amino acids, including a cysteine residue, and removed the normal stop codon. Since the cysteine residues at the C terminus are important for disulphide bond formation and tertiary structure of the agouti signaling protein, the deletion is expected to cause a dysfunction of ASIP as an antagonist of alpha-MSH in the Y*RB allele. This is the first evidence that the ASIP gene, known to be involved in coat color variation in mammals, is functional and has a similar effect on plumage color in birds.     

Variation of coat color in house mice throughout Asia

Coat color variation due to melanin pigment synthesis in house mice Mus musculus in Asia is described and found to be consistent with Gloger's rule, which states that individuals of endothermic animals are darker in humid habitats than those in drier habitats. Three properties of coat color (hue, value and chroma) were measured, and a lightness variable was derived from a principal components analysis using 428 skin specimens representing three subspecies from 85 localities. Dorsal coat color ranged from yellow through brown to black, whereas ventral coat color ranged from white to black. Dorsal coat color varied less than the ventral color. In our samples, the variation in coat color in natural populations was far less than that observed in the laboratory. We found a significant correlation between the lightness variable of dorsal coat color and precipitation. Dark coat color was observed in more humid and closed habitats (darker background color), and pale coat color in drier, more open habitats (lighter background color). This result might imply the role of concealment as a selective force affecting dorsal coat color that was observed in house mice. We also discussed other selective forces that could affect the coat color variation in house mice, such as resistance to bacterial degradation and thermoregulation. In addition, the color spectra of the dorsal pelage among the three subspecies were different, the major distinction being the environmental background color of the habitats in which they are distributed.     

Interaction of the Murine Dilute Suppressor Gene (Dsu) with Fourteen Coat Color Mutations

The murine dilute suppressor gene, dsu, was previously shown to suppress the dilute coat color phenotypes of mice homozygous for the dilute (d), leaden (ln), and ashen (ash) mutations. Each of these mutations produce adendritic melanocytes, which results in an abnormal transportation of pigment granules into the hair shaft and a diluted coat color. The suppression of each mutation is associated with the restoration of near normal melanocyte morphology, indicating that dsu can compensate for the absence of normal d, ln and ash gene products. In experiments described here, we have determined whether dsu can suppress the coat color phenotype of 14 additional mutations, at 11 loci, that affect coat color by mechanisms other than alterations in melanocyte morphology. In no case was dsu able to suppress the coat color phenotype of these 14 mutations. This suggests that dsu acts specifically on coat color mutations that result from an abnormal melanocyte morphology. Unexpectedly, dsu suppressed the ruby eye color of ruby-eye (ru) and ruby-eye-2 (ru-2) mice, to black. The exact nature of the defect producing these two mutant phenotypes is unknown. Histological examination of the pigmented tissues of the eyes of these mice indicated that dsu suppresses the eye color by increasing the overall level of pigmentation in the choroid but not the retinal pigmented epithelium. Choroid melanocytes, like those in the skin, are derived from the neural crest while melanocytes in the retinal pigmented epithelium are derived from the optic cup. This suggests that dsu may act specifically on neural crest-derived melanocytes. These studies have thus identified a second group of genes whose phenotypes are suppressed by dsu and have provided new insights into the mechanism of action of dsu.     

A blond coat color variation in meadow vole (Microtus pennsylvanicus)

Color mutations occur frequently among rodents. Here we describe a blond coat color mutation in the meadow vole (Microtus pennsylvanicus) that arose in a captive breeding colony established from wild-caught animals from southern Illinois. The blond coat coloration results from changes in the color and distribution of pigments in the hair. The mutation is monogenic autosomal recessive.     

Inheritance of coat color in the mole vole (Ellobius talpinus Pallas)

Based on the ecological features of the mole vole, family analysis of the inheritance of coat color was performed with the use of material collected in a wild population. Analysis of coat color in parents and offspring has demonstrated that the offspring segregation into black and nonblack animals after crosses of different types agrees with the hypothesis on the monogenic inheritance of these color variations. Black mole voles are homozygous for the recessive allele (genotype aa). Homozygotes for the dominant allele (AA) are brown. Heterozygotes (Aa) may be brown or have transitional color. The mean frequency of brown coat color in heterozygotes is 0.509 and is very variable. The higher the color intensity in black elements of parent coat color, the more is the offspring coat color saturated with these elements.     

Inheritance of seed condensed tannins and their relationship with seed-coat color and pattern genes in common bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.)

Condensed tannins are major flavonoid end products that affect the nutritional quality of many legume seeds. They chelate minerals and interact with proteins, thus reducing their bioavailability. Tannins also contribute to seed coat color and pigment distribution or intensity. The objective of this study was to analyze the relationship between quantitative trait loci (QTL) for seed tannin concentration in common bean and Mendelian genes for seed coat color and pattern. Three populations of recombinant inbred lines, derived from crosses between the Andean and Mesoamerican genepools were used for QTL identification and for mapping STS markers associated with seed color loci. Seed coat condensed tannins were determined with a butanol–HCl method and a total of 12 QTL were identified on separate linkage groups (LGs) in each of the populations with individual QTL explaining from 10 to 64% of the phenotypic variation for this trait. Loci on linkage groups B3 and B10 were associated with the Mendelian genes Z and Bip for partly colored seed coat pattern, while a QTL on linkage group B7 was associated with the P gene which is the primary locus for the control of color expression in beans. In conclusion, this study found that the inheritance of tannin concentration fits an oligogenic model and identifies novel putative alleles at seed coat color and pattern genes that control tannin accumulation. The results will be important for the genetic improvement of nutritionally enhanced or biofortified beans that have health promoting effects from higher polyphenolics or better iron bioavailability.     

Inheritance of Coat Color in the Mole Vole (<Emphasis Type="Italic">Ellobius talpinus</Emphasis> Pallas)

Based on the ecological features of the mole vole, family analysis of the inheritance of coat color was performed with the use of material collected in a wild population. Analysis of coat color in parents and offspring has demonstrated that the offspring segregation into black and nonblack animals after crosses of different types agrees with the hypothesis on the monogenic inheritance of these color variations. Black mole voles are homozygous for the recessive allele (genotype aa). Homozygotes for the dominant allele (AA) are brown. Heterozygotes (Aa) may be brown or have transitional color. The mean frequency of brown coat color in heterozygotes is 0.509 and is very variable. The higher the color intensity in black elements of parent coat color, the more is the offspring coat color saturated with these elements.     

The Results of Sable (<Emphasis Type="Italic">Martes zibellina</Emphasis>) Reintroduction Demonstrate the Founder Effect

The relative abundance of intrapopulation groups with different parameters of skull size, coat color, and expression of an epigenetic cranial trait was compared in autochthonous, reintroduced, and donor populations of sable. Recovery of the species resources and broad variability of the phenotypic trait complex in the newly fomned populations were observed. A large proportion of the animals had the phenotype that included large size, dark coat color, and pronounced expression of a specific phene trait (foramen in the condylar fossa) and was not characteristic of the neighboring autochthonous populations. It is reasonable to attribute the presence of individuals with an unusual morphology in the newly formed populations of animals to a manifestation of the founder principle, because the effect of this principle was promoted by spatial isolation of the primary foci of translocated animals.     

Generation and mapping of SCAR and CAPS markers linked to the seed coat color gene in Brassica napus using a genome-walking technique.

The yellow seed coat trait in No. 2127-17, a resynthesized purely yellow Brassica napus line, is controlled by a single partially dominant gene, Y. A double-haploid population derived from the F1 of No. 2127-17 x 'ZY821' was used to map the seed coat color phenotype. A combination of AFLP analysis and bulked segregant analysis identified 18 AFLP markers linked to the seed coat color trait. The 18 AFLP markers were mapped to a chromosomal region of 37.0 cM with an average of 2.0 cM between adjacent markers. Two markers, AFLP-K and AFLP-H, bracketed the Y locus in an interval of 1.0 cM, such that each was 0.5 cM away from the Y locus. Two other markers, AFLP-A and AFLP-B, co-segregated with the seed color gene. For ease of use in breeding programs, these 4 most tightly linked AFLP markers were converted into reliable PCR-based markers. SCAR-K, which was derived from AFLP-K, was assigned to linkage group 9 (N9) of a B. napus reference map consisting of 150 commonly used SSR (simple sequence repeat) markers. Furthermore, 2 SSR markers (Na14-E08 and Na10-B07) linked to SCAR-K on the reference map were reversely mapped to the linkage map constructed in this study, and also showed linkage to the Y locus. These linked markers would be useful for the transfer of the dominant allele Y from No. 2127-17 to elite cultivars using a marker-assisted selection strategy and would accelerate the cloning of the seed coat color gene.     

白色獭兔蓝眼突变体的发现与遗传分析

文章设计了杂交、回交和全同胞交配3个实验, 对美系白色獭兔(♂)和青紫蓝肉兔(♀)杂交所产生的白色蓝眼獭兔突变体的遗传机制进行了等位性测试。结果表明, 白色獭兔蓝眼突变体是维也纳座位(V)发生隐性突变的结果。基因v纯合(vv)对家兔基本毛色基因座(A、B、C、D、E)具有隐性上位作用, 无论其他毛色座位的基因型如何, 只要vv存在即可产生白色蓝眼兔。vv基因型与rr基因型组合即可产生白色蓝眼獭兔。白色蓝眼獭兔突变体在我国家兔育种中是一个新发现, 其遗传机制的阐明, 对獭兔育种和生产具有重要的指导意义。     

Body and organ mass in agouti and non-agouti deer mice (Peromyscus maniculatus).

Body, adrenal, brain, heart, liver, kidney, spleen and testis masses were determined for agouti and non-agouti deer mice (Peromyscus maniculatus gracilis) of both sexes. Body mass was highest for non-agouti females and lowest for agouti females; and sex differences in body mass were significant for agouti, but not non-agouti, deer mice. Adrenal, brain and liver masses were similar between color morphs; heart mass was greater in agouti males; and kidney, spleen and testis masses were all significantly greater for non-agouti deer mice. Splenomegaly in non-agouti deer mice was prominent, as spleens of non-agouti deer mice were 50% larger than those of agouti animals. Sex differences varied across organs and color morphs. For both color morphs, males had heavier adrenals and brains, whereas females had heavier livers and spleens. Kidney and heart mass was greater for female non-agouti deer mice, but for agouti animals, heart mass was greater in males and kidney mass differed little between the sexes. For both color morphs, testes and spleen mass was altered by photoperiod in 72 deer mice housed under short- or long-day conditions and the effect was stronger in non-agouti animals. This is the first report of splenomegaly and sex-specific body mass differences associated with the non-agouti allele.     

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。     

Circling,deafness, and yellow coat displayed by yellow submarine (ysb) and light coat and circling (lcc) mice with mutations on chromosome 3

We describe here two mouse mutants, yellow submarine (Ysb) and light coat and circling (Lcc). Ysb arose as the result of insertions of a transgene, pAA2, into the genome. Lcc is an independent, radiation-induced mutation. Both mutants are characterized by recessive circling behavior and deafness, associated with a non-segregating, semi-dominant yellow coat color. Complementation tests showed that Ysb and Lcc are allelic. We attribute the yellow coat in Ysb and Lcc mice to the absence of black awl overhairs, increased agouti zigzag underhairs, and the presence of agouti awls with long subapical yellow pigment. Chromosomal mapping and genomic characterization showed the Ysb and Lcc mutations involve complex chromosomal rearrangements in overlapping regions of mouse chromosome 3, A2/A3-B/C and B-E1, respectively. Ysb and Lcc show for the first time, to our knowledge, the presence of genes in the B-C region of chromosome 3 important for balance and hearing and the pigmentation and specification of coat hair.