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PubMed1999

A system for rapid generation of coat color-tagged knockouts and defined chromosomal rearrangements in mice.

Gene targeting in mouse embryonic stem (ES) cells can be used to generate single gene mutations or defined multi-megabase chromosomal rearrangements when applied with the Cre- loxP recombination system. While single knockouts are essential for uncovering functions of cloned genes, chromosomal rearrangements are great genetic tools for mapping, mutagenesis screens and functional genomics. The conventional approach to generate mice with targeted alterations of the genome requires extensive molecular cloning to build targeting vectors and DNA-based genotyping for stock maintenance. Here we describe the design and construction of a two-library system to facilitate high throughput gene targeting and chromo-somal engineering. The unique feature of these libraries is that once a clone is isolated, it is essentially ready to be used for insertional targeting in ES cells. The two libraries each bear a complementary set of genetic markers tailored so that the vector can be used for Cre- loxP -based chromosome engineering as well as single knockouts. By incorporating mouse coat color markers into the vectors, we illustrate a widely applicable method for stock maintenance of ES cell-derived mice with single gene knockouts or more extensive chromosomal rearrangements.

Agouti Signaling Protein↗
PubMedDate not supplied

The use of a wild pig x domestic pig intercross to map phenotypic trait loci.

Intercrosses between divergent lines of domestic animals adapted to different environmental conditions and/or production systems provide unique opportunities for mapping phenotypic trait loci. The strategy resembles the use of interspecific crosses developed for general linkage mapping. We have made an intercross between the wild pig and domestic pigs of the Large White breed. A comprehensive linkage map comprising more than 230 genetic markers has been established. The successful use of this intercross for mapping loci for some monogenic traits (coat color and an intestinal receptor for E. coli K88 pili) as well as quantitative trait loci (QTLs) with major effects of growth and fatness is reviewed.

Animals↗
PubMed1984

The relationship between alpha-MSH level and coat color in white Camarque horses.

White horses are subject to age-dependent coat depigmentation. They are dark gray or black at birth and lose their coloring between their second and fourth year. Beginning at about age 10 their coat takes on a characteristic silver-gray coloring. The purpose of this paper was to find out to what extent the endogenic alpha-MSH level changes with the change in pigmentation. alpha-MSH plasma levels were determined by radioimmunologic analysis in 3 age groups of white Camarque horses: age group 1 consisted of dark horses with a mean age of 1.2 years and a mean alpha-MSH level of 106.4 pg/ml +/- 18.2, age group 2 consisted of gray horses with a mean age of 7.5 years and with a mean alpha-MSH level of 73.6 pg/ml +/- 4.8, and age group 3 consisted of silver-gray horses with a mean age of 13.5 years and a mean alpha-MSH level of 65.0 pg/ml +/- 5.3. Highly significant differences (p less than 0.001) were found between the means of age group 1 and age group 2 and between the means of age group 1 and age group 3. Determination of the ACTH plasma levels in this breed of horses showed no statistically significant differences between the various age groups. Determination of alpha-MSH and ACTH levels in a control group (n = 56) of other breeds of horses (10 black, 28 brown, and 18 sorrel) resulted in no significant differences for either hormone with regard to age or coat color. On the basis of these results it may be concluded that the degree of coat pigmentation in white Camarque horses correlates directly with the alpha-MSH plasma level.

Adrenocorticotropic Hormone↗
PubMed2002

Estrogen accelerates gonadal recrudescence in photo-regressed male siberian hamsters.

Seasonal gonadal recrudescence in the male Siberian hamster is accompanied by the initiation of spermatogenesis, weight gain, and darkening of coat color. The downstream endocrine regulators responsible for these changes have been definitively identified. We have previously shown that the administration of exogenous 17beta-estradiol (E(2)) to adult male Siberian hamsters kept under long-day photoperiod increased testicular mass without altering spermatogenesis. In this study, we examine if E(2) can initiate testicular growth in photo-regressed adult Siberian hamsters and if this testicular growth is accompanied by weight gain and pelage color change. Photo-regressed adult male Siberian hamsters were subcutaneously implanted with a 1 mm silastic capsule containing E(2) or cholesterol control. After 15 days, robust initiation of spermatogenesis was observed in E(2)-implanted animals in the absence of body weight and pelage color change. While circulating follicle-stimulating hormone (FSH) remained undetected in both control and E(2)-treated animals, E(2) significantly reduced pituitary gonadotropin stores. Overall, we showed E(2) stimulated gonadal recrudescence via a pathway that has diverged from body weight and pelage color change. Further, we demonstrated a novel role of E(2) in the initiation of spermatogenesis, possibly via a mechanism independent of FSH.

Animals↗
PubMed1990

Social preference of female gerbils (Meriones unguiculatus) as influenced by coat color of males.

Female gerbils (Meriones unguiculatus) of three distinct coat colors (agouti, black, and sandy or pink-eyed dilution) were tested in a Y-maze whose arms led to compartments containing unfamiliar male gerbils of varying coat colors. The stimulus animals were separated from the females by a Plexiglas door. The trials lasted for 2 min and each female was exposed to the following four combinations: two males of the same coloring as the female; one male of the same color and another of a different color from the female; both males of different color from the female. The number of crossings to the left and right arms was relayed by photocells to an IBM PC computer. The results indicate that agouti females preferred visiting the arm occupied by agouti males while those of the other coat colors showed no preference for the "wild-type" males. Instead, sandy and black female gerbils preferred to be in proximity with those of non-wild types.

Animals↗
PubMed1996

The genetics of pigmentation: from fancy genes to complex traits.

Genes that control mammalian pigmentation interact with each other in intricate networks that have been studied for decades using mouse coat color mutations. Molecular isolation of the affected genes and the ability to study their effects in a defined genetic background have led to surprising new insights into the potential interaction between tyrosine kinase and G-protein-coupled signaling pathways. Recent developments show that homologous genes in humans are responsible not only for rare diseases, such as albinism and piebaldism, but also for common phenotypic variations, such as red hair and fair skin.

Animals↗
PubMed1998

Effects of genic substitution at the agouti, brown, albino, dilute, and pink-eyed dilution loci on the proliferation and differentiation of mouse epidermal melanocytes in serum-free culture.

To examine the effects of coat-color genes on the proliferation and differentiation of mouse epidermal melanocytes, we cultured epidermal, cell suspensions derived from neonatal skins of C57BL/10JHir (black) and its congenic mice carrying agouti, brown, albino, dilute, and pink-eyed dilution genes in a serum-free medium supplemented with dibutyryl adenosine 3',5'-cyclic monophosphate. The proliferative rates of agouti, brown and dilute black melanocytes were similar to that of black melanocytes, while those of albino and pink-eyed black melanocytes were about one-half of that of black melanocytes. The morphology of albino and pink-eyed black melanocytes, though nonpigmented, was similar to black melanocytes; namely, dendritic, polygonal or epithelioid. Dilute black melanocytes also possessed the similar morphology, whereas their melanosomes were accumulated in the perinuclear region. Dopa-melanin depositions after dopa reaction in brown and dilute black melanocytes were greater than in black and agouti melanocytes. Although dopa-melanin depositions were not observed in albino melanocytes, about 8% of pink-eyed black melanocytes were positive to dopa reaction. Silver depositions after combined dopa-premelanin reaction in agouti, brown and dilute black melanocytes were similar to that in black melanocytes. Although albino melanocytes were devoid of silver depositions, about 25% of pink-eyed black melanocytes were positive to the reaction. Pyrrole-2,3,5-tricarboxylic acid (PTCA, degradation product of eumelanin) contents in agouti and dilute black melanocytes were slightly lower than in black melanocytes, while that in brown melanocytes was reduced to one-third. In contrast, PTCA contents in albino and pink-eyed black melanocytes were reduced to less than 0.5%. Aminohydroxyphenylalanine (AHP, degradation product of pheomelanin) contents did not differ among these melanocytes. These results suggest that the coat-color genes exert their influences on the proliferation and differentiation of mouse epidermal melanocytes by affecting tyrosinase activity, melanosome maturation and transport, and eumelanin synthesis.

Animals↗
PubMed1991

In utero manipulation of coat color formation by a monoclonal anti-c-kit antibody: two distinct waves of c-kit-dependency during melanocyte development.

Previous studies on mice bearing various mutations within the c-kit gene, dominant white spotting (W), indicate the functional role of this tyrosine kinase receptor in the development of melanocytes, germ cells and hematopoietic cells. Despite the availability of mice defective in the c-kit gene and a respectable understanding of the molecular nature of c-kit, however, it is not clear at what stage of gestation c-kit is functionally required for the development of each of these cell lineages. To address this question, we have used a monoclonal anti-c-kit antibody, ACK2, as an antagonistic blocker of c-kit function to interfere with the development of melanocytes during embryonic and postnatal life. ACK2 injected intradermally into pregnant mice entered the embryos where it blocked the proper development of melanocytes. This inhibitory effect was manifested as coat color alteration in the offspring. Furthermore, ACK2 injection also altered the coat color of neonatal and adult mice. Based on the coat color patterns produced by ACK2 administration at various stages before or after birth, the following conclusions are drawn: (i) during mid-gestation, c-kit is functionally required during a restricted period around day 14.5 post-coitum when a sequence of events leading to melanocyte entry into the epidermal layer occurs; (ii) during postnatal life, c-kit is required for melanocyte activation which occurs concomitantly with the hair cycle which continues throughout life after neonatal development of the first hair.

Animals↗
PubMedDate not supplied

Genetics of the W locus in foxes and expression of its lethal effects.

The Georgian white mutation for coat color in foxes is inherited as a partially dominant character. It is allelic to the previously observed white-faced and platinum mutations. It was established that large litter size in Georgian white females and long daylight during pregnancy promote embryonic viability in homozygotes for this mutation. As a result, in offspring segregation patterns for coat color the proportion of homozygotes increases and that of heterozygotes decreases. It is suggested that a competitive relationship between embryos with different genotypes is established as early as at the preimplantation stage.

Alleles↗
PubMed2002

A study of relative horn fly, Haematobia irritans (Diptera: Muscidae), abundance on Holstein steers and steers of two Holstein crosses.

A study was performed to determine if the number of horn fly (Haematobia irritans) adults differ significantly on Holstein (black and white coat color), Holstein x Holstein Friesian (black and white coat color) and Holstein x Jersey (black coat color) steers, 10-12 months old at the onset of the study. All steers were run together on lucerne paddocks and the number of flies counted at 30-day intervals from September 2000 to August 2001. No significant differences (P > 0.05, test of Kruskal-Wallis) were found in fly numbers, even in the period April-May 2001 when the infestation reached its peak. We were unable to demonstrate that coat color influenced horn fly abundance in the present study. It appears that none of the biotypes evaluated had any advantage for natural control of H. irritans.

Animals↗
PubMed2000

Melanocortin 1 receptor variation in the domestic dog.

The melanocortin 1 receptor (Mc1r) is encoded by the Extension locus in many different mammals, where a loss-of-function causes exclusive production of red/yellow pheomelanin, and a constitutively activating mutation causes exclusive production of black/brown eumelanin. In the domestic dog, breeds with a wild-type E allele, e. g., the Doberman, can produce either pigment type, whereas breeds with the e allele, e.g., the Golden Retriever, produce exclusively yellow pigment. However, a black coat color in the Newfoundland and similar breeds is thought to be caused by an unusual allele of Agouti, which encodes the physiologic ligand for the Mc1r. Here we report that the predicted dog Mc1r is 317 residues in length and 96% identical to the fox Mc1r. Comparison of the Doberman, Newfoundland, Black Labrador, Yellow Labrador, Flat-coated Retriever, Irish Setter, and Golden Retriever revealed six sequence variants, of which two, S90G and R306ter, partially correlated with a black/brown coat and red/yellow coat, respectively. R306ter was found in the Yellow Labrador, Golden Retriever, and Irish Setter; the latter two had identical haplotypes but differed from the Yellow Labrador at three positions other than R306ter. In a larger survey of 194 dogs and 19 breeds, R306ter and a red/yellow coat were completely concordant except for the Red Chow. These results indicate that the e allele is caused by a common Mc1r loss-of-function mutation that either reoccurred or was subject to gene conversion during recent evolutionary history, and suggest that the allelic and locus relationships for dog coat color genes may be more analogous to those found in other mammals than previously thought.

Alleles↗
PubMed2000

Nomenclature for identified pigmentation genes in the mouse.

More than 90 different loci influence pigmentation in the mouse. During the past few years, an increasing number of genes have been identified, and assigned to the corresponding coat color loci and pigmentation mutants. As a consequence, different names have been used in publications for loci, genes and corresponding proteins. In the following article, we present the rules and guidelines for gene nomenclature, and provide the current nomenclature for pigmentation mutants in the mouse.

Animals↗
PubMed2000

Establishment and characterization of the MSKR inbred strain originated from Japanese wild mice (Mus musculus molossinus).

A new inbred strain, MSKR, originated from Japanese wild mice was established in April, 1998. The MSKR mice were 60% of the C57BL/6N inbred mice in the 60-day body weight. Tail length/head-body length and hind-foot length/head-body length of the MSKR mice were significantly smaller than those of the C57BL/6N mice (0.896 vs 1.061, 0.189 vs 0.204), but ear length/head-body length of the MSKR mice was significantly larger than that of the C57BL/6N mice (0.143 vs 0.137). The age of the first parturition and size of the first litter were 63.20 +/- 2.71 days and 6.20 +/- 0.37, respectively, at the 20th and 22nd inbreeding generations. Genetic characterization of the MSKR strain was performed using 34 microsatellite markers, 29 biochemical markers, 9 immunogenetic markers, 3 coat color markers, and mitochondrial DNA RFLP-haplotypes. The result indicated that this newly established inbred strain has some different gene constitution from already known molossinus and common laboratory strains.

Animals↗
PubMedDate not supplied

[Polymorphism of the fur pigmentation genes and the hormonal adaptation system in the water vole (Arvicola terrestris)].

Postnatal ontogenesis of hormonal system of hypophysis - adrenal glands and hormonal reaction under stress conditions were examined in adult water mouse, which had polymorphic fur color genes. Black females (genotype aa), opposite to brown ones, (genotype AA, Aa) had changed postnatal ontogenesis of adrenal glands function and they had not hormonal reaction to the two days water deprivation.

Adaptation, Physiological↗
PubMedDate not supplied

Spleen-shape as a genetic marker in X/Gf mice.

This study revealed that the triangular shaped spleen of X/Gf mice constitutes a genetically dominant characteristic over normal spleen shape of C3H mice. The agouti coat color of C3H mice is dominant over the white color of the X/Gf strain. The mode of transmission of triangular shape of the spleen in X/Gf mice, as well as their white coat color indicates Mendelian autosomal inheritance involving two independent genes. Although the pedigree lends support to this inference, we are aware that the small number of F2 offspring available for this study limits the conclusions to be drawn from the segregation ratio and statistical evaluation.

Animals↗
PubMed2004

[Studies of hereditary conditionality index on some morphological characters of Tupaia belangeri chinensis].

Tree shrew is a kind of excellent experimental animal resource in medical science and biology. In this paper, 35 Tupaia blangeri chinensises (TBCs) captured from Kunming,Yunnan province were investigated. We analyzed hereditary conditionality index about some morphological characters. According to Rife-Buranamanas law, we analyzed the appearance characteristics with hereditary conditionality including color of fur, orbit etc. The results showed the following: wild fur with seasonal red spot, white fur of abdomen, non-white orbit, flesh-color palm, non-cocked ear, round tip tail, and the line between the breasts of both sides in a vertical position with axis line.

Animals↗
PubMedDate not supplied

Inheritance of tweed, a modification of merle, in Australian shepherd dogs.

An autosomal mutation is responsible for the modification of merle coat color (previously indicated to be due to a transposable DNA element) to the tweed merle pattern in the Australian shepherd dog. The tweed merle pattern consists of color patches that have a greater range in the intensity of the dilute patches and tend to be larger than the patches of nontweed merle. It has no action on nonmerle dogs. The symbol Tw is proposed for this gene.

Animals↗