Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hair Color”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMedDate not supplied

Brown and rust mutants of the Syrian hamster are p and b genes of mammalian coat colors.

The mutant genes of the Syrian hamster, which were originally designated as brown (b) and rust (r), are shown by morphological and phenotypic criteria, as well as by linkage studies in the case of brown, to be homologous with pink-eyed dilution (p) and brown (b), respectively, two well established loci in the genetics of mammalian pigmentation. It is proposed that the two mutants be appropriately redesignated.

Animals↗
PubMed2004

Melanin acts as a potent UVB photosensitizer to cause an atypical mode of cell death in murine skin.

Melanin protects the skin against DNA damage induced by direct absorption of sunlight's UV radiation. Yet, irradiating melanin in vitro or in cultured cells also generates active oxygen species such as superoxide, which can indirectly induce oxidative base lesions and DNA strand breaks. This photosensitization is greater for pheomelanin (yellow and red melanin) than for eumelanin (brown and black). The in vivo photosensitizing ability of melanin is unknown. We used congenic mice of black, yellow, and albino coat colors to investigate the induction of DNA lesions and apoptosis after exposure to predominantly UVB (280-320 nm) or UVA (320-400 nm) radiation. Cyclobutane pyrimidine dimers induced by direct UVB absorption were equal in all three strains, as was apoptosis measured as sunburn cells or as keratinocytes containing active caspase-3. However, terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL)-positive cells were approximately 3-fold more frequent in black and yellow mice after UVB or UVA irradiation than in albino. In epidermal sheets, TUNEL-positive cells lined the upper portion of the hair follicle, consistent with UV-induced photosensitization by melanin in the hair shaft. Because the concentration of eumelanin in black mice was three times that of pheomelanin in yellow mice, pheomelanin had 3-fold greater specific activity. We conclude that UV-irradiated melanin, particularly pheomelanin, photosensitizes adjacent cells to caspase-3 independent apoptosis, and this occurs at a frequency greater than the apoptosis induced by direct DNA absorption of UV. Melanin-induced apoptosis may contribute to the increased sensitivity of individuals with blonde and red hair to sunburn and skin cancer.

Animals↗
PubMed1994

The agouti gene: turned on to yellow.

The agouti locus was first identified as a result of its effects on the type and temporal deposition of coat color pigments in mammals. Many mutations at the murine agouti locus have now been found, some of which not only affect coat color, but also interfere with diverse biological processes leading to diabetes, obesity, tumor susceptibility and embryonic lethality. Correlations between the genotype and phenotype of agouti mutants, as well as reasons for the pleiotropy of effects caused by agouti mutations, have begun to unfold with the molecular cloning of the agouti gene and its surrounding genomic region.

Agouti Signaling Protein↗
PubMed2002

Mutant laboratory mice with abnormalities in pigmentation: annotated tables.

Mammalian pigment cell research has recently entered a phase of significantly increased activity due largely to the exploitation of the many mutant mouse stocks that are coming on stream. Numerous transgenic, targeted mutagenesis (so-called 'knockouts'), conditional (so-called 'gene switch') and spontaneous mutant mice develop abnormal coat color phenotypes. The number of mice that exhibit such abnormalities is increasing exponentially as genetic engineering methods become routine. Since defined abnormalities in such mutant mice provide important clues to the as yet often poorly understood functional roles of many gene products, this overview includes a corresponding, annotated table of mutant mice with pigmentation alterations. These range from early developmental defects via a large array of coat color abnormalities to a melanoma metastasis model. This overview should provide helpful pointers to investigators who are looking for mouse models to explore or to compare functional activities of genes of interest and for comparing coat color phenotypes of spontaneous or genetically engineered mouse mutants with novel ones. Secondly, this review includes a table of mouse models of specific human diseases with genetically defined pigmentation abnormalities. In summary, this annotated table should serve as a useful reference for anyone interested in the molecular controls of pigmentation.

Animals↗
PubMed2004

Coat color-tagged green mouse with EGFP expressed from the RNA polymerase II promoter.

Laborious molecular genotyping and variegated gene expression are two widely encountered issues for transgenic mouse studies. To facilitate genotyping in the FVB/N albino background and to reduce variegated expression, we successfully generated double-tagged transgenic mice for direct visual genotyping with the coat color phenotype derived from tyrosinase cDNA driven by the tyrosinase promoter and with simultaneous high enhanced green fluorescent protein (EGFP) expression driven by the promoter of RNA polymerase II large subunit gene. Incorporation of insulator into a transgene construct achieved high efficiency of transgene expression in more than 90% of the founders. EGFP was detected as early as the one-cell fertilized egg and lasted for the whole embryo development, as well as in all of the adult tissues examined. The coat color-tagged green mice offer opportunities in applications such as tissue transplantation, lineage tracing, chimera biology, RNA interference, and other transgenic studies.

Animals↗
PubMed2006

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.

Adaptation, Biological↗
PubMed1997

Genetic studies of the mouse mutations mahogany and mahoganoid.

The mouse mutations mahogany (mg) and mahoganoid (md) are negative modifiers of the Agouti coat color gene, which encodes a paracrine signaling molecule that induces a swithc in melanin synthesis from eumelanin to pheomelanin. Animals mutant for md or mg synthesize very little or no pheomelanin depending on Agouti gene background. The Agouti protein is normally expressed in the skin and acts as an antagonist of the melanocyte receptor for alpha-MSH (Mc1r); however, ectopic expression of Agouti causes obesity, possibly by antagonizing melanocortin receptors expressed in the brain. To investigate where md and mg lie in a genetic pathway with regard to Agouti and Mc1r signaling, we determined the effects of these mutations in animals that carried either a loss-of-function Mc1r mutation (recessive yellow, Mc1re) or a gain-of-function Agouti mutation (lethal yellow, Ay). We found that the Mc1re mutation suppressed the effects of md and mg, but that md and mg suppressed the effects of Ay on both coat color and obesity. Plasma levels of alpha-MSH and of ACTH were unaffected by md or mg. These results suggest that md and mg interfere directly with Agouti signaling, possibly at the level of protein production or receptor regulation.

Adrenocorticotropic Hormone↗
PubMed2002

Prediction of adoption versus euthanasia among dogs and cats in a California animal shelter.

The purpose of this retrospective cohort study was to investigate determinants of adoption of cats and dogs from a large municipal animal shelter. The subjects were 4,813 cats and 3,301 dogs impounded by the Sacramento County Department of Animal Care and Regulation and offered for adoption September 9, 1994 to May 26, 1995. The study constructed models predicting the conditional probability of adoption using logistic regression and a final multiple logistic regression model from variables found to be important predictors of adoption. Age, sex, coat color, and reason for relinquishment were major determinants of adoption in cats. Age, sex, coat color, reason for relinquishment, breed, purebred status, and injury status were major determinants of adoption in dogs. Shelter personnel could utilize this information to increase the adoption of frequently overlooked animals. Alternatively, shelters could use this to focus their resources on animals with characteristics the public prefers.

Age Factors↗
PubMed1984

Transplacental genetic and cytogenetic effects of alkylating agents in the mouse. I: Induction of somatic coat color mutations.

Induction of somatic coat color mutations by the alkylating agents ENU, MNU, EMS, MMS, DES, DMS, and trenimon and by the tuberculostatic drug INH was investigated in the mammalian spot test. Positive results were obtained with EMS (100 mg/kg), ENU (20-60 mg/kg), and INH (100 mg/kg), while trenimon (100 micrograms/kg), DES (225 mg/kg), and MNU (2 mg/kg) yielded inconclusive data. No mutagenic activity was found for MMS (125 mg/kg) and DMS (50 mg/kg). The mutagenic potency of monofunctional alkylating agents at subtoxic doses decreases as follows ENU greater than EMS greater than DES greater than MMS = DMS. The hypothesis that somatic coat color mutations in the mouse are predominantly due to intragenic changes is discussed. Differences in the RS frequency between offspring of the crosses NMRI X DBA and C57 X T are due to differences in loci available for mutation induction. Mutations that uncover the recessive allele p contribute to a significant extent to the total RS frequency observed in the mammalian spot test.

Alkylating Agents↗
PubMed2000

Genetics of chemical carcinogenesis: analysis of bidirectional selective breeding inducing maximal resistance or maximal susceptibility to 2-stage skin tumorigenesis in the mouse.

We report on bidirectional selective breeding, initiated from a genetically defined foundation population and carried out to selection limit, for producing lines of mice endowed with maximal resistance (Car-R) or maximal susceptibility (Car-S) to 2-stage skin tumorigenesis. The initial population resulted from a balanced intercrossing of 8 inbred strains of mice. The tumors, induced by a single application of DMBA (initiation) and twice weekly applications of TPA (promotion), were benign papillomas; their number at the end of the promotion period was the phenotype chosen for assortative mating. Afterward, the majority of them regressed while others progressed to malignant carcinomas. The Car-R line was selected through a strong challenge, while the Car-S line selection was based on responses to decreasing concentrations of DMBA and TPA. The selection limit was reached after 14 or 15 generations showing progressive interline divergence, which strongly suggests the interaction of several quantitative trait loci (QTL). The phenotypic difference was extremely large: the tumor response was 73 times higher in Car-S than in Car-R mice, though the applied concentrations of DMBA and TPA were 100 and 40 times lower, respectively. The mean heritability realized during the selective breeding was 0.20 in Car-R and 0.49 in Car-S. Our results are compatible with a minimal QTL estimate of 8 in the Car-R line and of 9 or 10 in the Car-S line. The Car-S line is also much more susceptible to carcinoma induction. An association of coat color with tumorigenesis was observed in interline F2 segregants. The Car-R and Car-S lines, obtained through a long-lasting breeding program, are a unique model for identifying the QTL involved in chemical tumorigenesis and will be provided to interested investigators.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

An extension locus mosaic Labrador retriever dog.

A mosaic male Labrador retriever with coat color of black and yellow areas is described. Matings of this dog to black, chocolate, and yellow Labrador bitches were consistent with his producing only yellow (e) gametes at the extension locus. His phenotype could have resulted either from somatic mutation of E to e or e to E early in development; or from fusion of Ee and an ee male zygotes to form a chimera.

Animals↗
PubMed1994

Localization of a N-ras-related sequence on rat chromosome 1.

Location of the locus for a restriction fragment length polymorphism of N-ras-related sequences (NRAS2) on the rat chromosome 1 was determined by linkage analysis using a microsatellite locus (KAL) and a coat-color locus (C). The recombination frequencies between NRAS2 and C, NRAS2 and KAL, and C and KAL in 57 backcross progeny obtained from crosses of (WKS/Iar x IS/Iar) x WKS/Iar were 7.0 +/- 3.4%, 28 +/- 5.9%, and 23 +/- 5.6%, respectively. The order of the three loci on the rat chromosome 1 was determined as follows: KAL-C-NRAS2.

Animals↗
PubMedDate not supplied

A linkage group composed of three coat color genes and three serum protein loci in horses.

The equine coat color genes chestnut (e) and roan (Rn) have been tested for linkage to 15 protein and blood group loci. Data showing close or fairly close linkage to the serum albumin locus (Al) and loose linkage to the serum esterase locus (Es) for both e and Rn are presented. This means that three coat color genes (To, e and Rn) and three serum protein loci (Al, Gc, and Es) are linked in the same linkage group. The gene order can tentatively be written Al, Gc, Rn, To-e-Es. The implications of the results for studies on coat color inheritance in horses are discussed. The possibility of using electrophoretic markers when testing hypotheses of allelism between coat color genes is suggested. The linkage of e and Es in the horse is proposed to be homologous to the loose linkage of the extension locus (e) and a cluster of esterase loci on chromosome 8 in the mouse, and on linkage group IV in the rabbit. Designations for the known autosomal linkage groups in the horse are suggested.

Animals↗
PubMed1987

Linkage of faded gene (fe) to chromosome 6 of the mouse.

Linkage tests on the faded gene were carried out with some coat color and biochemical markers, It was shown that the faded locus was not closely linked to the following loci: Idh-1 (chromosome 1), a (2), Car 2 (3), Mup-1 (4), Pgm-1 (5), Hbb (7), Gpi-1 (7), Es-1 (8), Trf (9), Es-3 (11), s (14), Sod-1 (16) and Ce-2 (17). The mutant locus showed linkage with Ggc on chromosome 6.

Animals↗
PubMed1994

Cloning, analysis, and chromosomal localization of myoxin (MYH12), the human homologue to the mouse dilute gene.

The mouse dilute gene encodes a novel type of non-muscle myosin that structurally combines elements from both nonmuscle myosin type I and nonmuscle myosin type II. Phenotypically, mutations in the mouse dilute gene result not only in the lightening of coat color, but also in the onset of severe neurological defects shortly after birth. This may indicate that the mouse dilute gene is important in maintaining the normal neuronal function in the mouse. We report the isolation and sequencing of "myoxin" (MYH12), the human homologue of the mouse dilute gene, and its assignment to human chromosome 15.

Amino Acid Sequence↗
PubMed2000

Quantitative trait loci that modify the sootiness of yellow pigmentation in KK-A(y)/a mice.

Compared with C57BL/6J-A(y)/a, KK-A(y)/a mice have yellow fur that is markedly darker. Furthermore, there is a considerable variation in the tone of color with a continuous range in F(2) progeny produced from C57BL/6J females and KK-A(y)/a males. The aims of this study are to reveal the phenotypic differences between the two A(y) congenic strains and to elucidate the genetic factors responsible for the sooty yellow pigmentation in the KK background. On the basis of a chemical analysis, the sootiness in KK-A(y)/a was the result of increased eumelanin (PTCA) and decreased pheomelanin (AHP). A statistically significant QTL was identified on Chromosome (Chr) 15, responsible for the AHP content. No significant loci responsible for PTCA were identified. On the other hand, on the basis of an optical analysis for color difference and overall sootiness, significant evidence of linkage was identified on the proximal part of Chr 15, in the region similar to AHP QTL. The overall sootiness is thus controlled solely by the locus on Chr 15 in F(2) progeny; however, the KK allele at this locus significantly increased the AHP content.

Alleles↗
PubMed1994

Molecular genetics of the brown (b)-locus region of mouse chromosome 4. I. Origin and molecular mapping of radiation- and chemical-induced lethal brown deletions.

Over a period of many years, germ-cell mutagenesis experiments using the mouse specific-locus test have generated numerous radiation- and chemical-induced alleles of the brown (b; Tyrp 1) locus in mouse chromosome 4. We describe here the origin, maintenance and initial molecular characterization of 28 b mutations that are prenatally lethal when homozygous. Each of these mutations is deleted for Tyrp 1 sequences, and each of 25 mutations tested further is deleted for at least one other locus defined by molecular clones previously found to be closely linked to b by interspecific backcross analysis. A panel of DNAs from mice carrying a lethal b mutation and a Mus spretus chromosome 4 was used in the fine structure mapping of these molecularly defined loci. The deletional nature of each of these prenatally lethal mutations is consistent with the hypothesis that the null phenotype at b has an effect only on the quality (color) of eumelanin produced in melanocytes. The resulting deletion map provides a framework on which to build future molecular-genetic and biological analyses of this region of mouse chromosome 4.

Alleles↗
PubMed1988

The dilute coat-color locus of mouse chromosome 9.

The genetic and molecular analysis clearly defines the dilute gene as essential for normal melanocyte morphology, neurological function and juvenile survival. The large number of dilute mutations afford a strong basis for clarifying the precise genomic organization and expression pattern at dilute. Ultimately, such an analysis will provide the tools for the subsequent molecular examination of the numerous loci which define the dilute complex of mouse chromosome 9 as critical for normal mammalian development.

Alleles↗