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PubMedDate not supplied

Brown coat color in Icelandic cattle produced by the loci Extension and Agouti.

Inheritance of the colors black, brown, and red in Icelandic cattle was studied. The three colors are produced by two loci, Extension (E) and Agouti (A), with three alleles at the E locus: E(d) for dominant black; E+, intermediate, which allows expression of A locus alleles; and e for recessive red color. Two alleles are postulated at the A locus: A+, producing brown, and a, producing recessive black (nonagouti) when homozygous in E+/- animals. The dominant and recessive types of black are indistinguishable from each other phenotypically. The A alleles are only able to express their effect in E+/- genotypes. The E and A loci in cattle are postulated to be homologous to the E and A loci in the mouse.

Alleles↗
PubMed1994

Targeted and natural (piebald-lethal) mutations of endothelin-B receptor gene produce megacolon associated with spotted coat color in mice.

Endothelins act on two subtypes of G protein-coupled receptors, termed endothelin-A and endothelin-B receptors. We report a targeted disruption of the mouse endothelin-B receptor (EDNRB) gene that results in aganglionic megacolon associated with coat color spotting, resembling a hereditary syndrome of mice, humans, and other mammalian species. Piebald-lethal (sl) mice exhibit a recessive phenotype identical to that of the EDNRB knockout mice. In crossbreeding studies, the two mutations show no complementation. Southern blotting revealed a deletion encompassing the entire EDNRB gene in the sl chromosome. A milder allele, piebald (s), which produces coat color spotting only, expresses low levels of structurally intact EDNRB mRNA and protein. These findings indicate an essential role for EDNRB in the development of two neural crest-derived cell lineages, myenteric ganglion neurons and epidermal melanocytes. We postulate that defects in the human EDNRB gene cause a hereditary form of Hirschsprung's disease that has recently been mapped to human chromosome 13, in which EDNRB is located.

Animals↗
PubMed1994

Analysis of behavioral and hippocampal variation in congenic albino and pigmented BALB mice.

Mice of the BALB/c strain are widely used in behavioral research in spite of the albino condition, which can obscure brain-behavior relationships. We have developed a pigmented BALB strain, congenic to BALB/c, which could be more appropriate for neurogenetic studies that aim at identifying the effects of neurological mutations on behavior. Comparison of inbred albino and pigmented congenic BALB arising from the same litters provides a valuable tool for detecting the consequences of the albino mutation on behavioral performances. Preliminary results presented here show that the albino condition does not interfere with the development and patterns of connectivity of mossy fibers in the hippocampus. On the other hand, obvious coat color-linked differences appear for locomotor activity and defecation scores in the open field, pigmented mice being unexpectedly less active and more reactive than albino, as if better vision increased their reactions to a novel, anxiogenic environment. Finally, pigmented mice do not show better performances in the radial maze, which confirms that the inability of BALB mice for spatial learning in a highly demanding version of this task cannot be attributed to their inability to process visual information.

Animals↗
PubMedDate not supplied

9-cis Retinal increased in retina of RPE65 knockout mice with decrease in coat pigmentation.

The protein RPE65 is essential for the generation of the native chromophore, 11-cis retinal, of visual pigments. However, the Rpe65 knockout (Rpe65-/-) mouse shows a minimal visual response due to the presence of a pigment, isorhodopsin, formed with 9-cis retinal. Isorhodopsin accumulates linearly with prolonged dark-rearing of the animals. The majority of Rpe65-/- mice have an agouti coat color. A tan coat color subset of Rpe65-/- mice was found to have an enhanced visual response as measured by electroretinograms. The enhanced response was found to be due to increased levels of 9-cis retinal and isorhodopsin pigment levels. Animals of both coat colors reared in cyclic light have minimal levels of regenerated pigment and show photoreceptor degeneration. On dark-rearing, pigment accumulates and photoreceptor degeneration is decreased. In the tan Rpe65-/- mice, the level of photoreceptor degeneration is less than in the agouti animals, which have an increased pigment and decreased free opsin level. Therefore, photoreceptor damage correlates with the amount of the apoprotein present, supporting findings that the activity from unregenerated opsin can lead to photoreceptor degeneration.

Animals↗
PubMed1999

Molecular and pharmacological characterization of dominant black coat color in sheep.

Dominant black coat color in sheep is predicted to be caused by an allele ED at the extension locus. Recent studies have shown that this gene encodes the melanocyte stimulating hormone receptor (MC1-R). In mouse and fox, naturally occurring mutations in the coding region of MC1-R produce a constitutively activated receptor that switches the synthesis from phaeomelanin to eumelanin within the melanocyte, explaining the black coat color observed phenotypically. In the sheep, we have identified a Met-->Lys mutation in position 73 (M73K) together with a Asp --> Asn change at position 121 (D121N) showing complete cosegregation with dominant black coat color in a family lineage. Only the M73K mutation showed constitutive activation when introduced into the corresponding mouse receptor (mMC1-R) for pharmacological analysis; however, the position corresponding to D121 in the mouse receptor is required for high affinity ligand binding. The pharmacological profile of the M73K change is unique compared to the constitutively active E92K mutation in the sombre mouse and C123R mutation in the Alaska silver fox, indicating that the M73K change activates the receptor via a mechanism distinct from these previously characterized mutations.

Animals↗
PubMed1987

[Demonstration of a correlation between the degree of pigmentation and the power of inactivation of isoniazid in man].

In a group of 153 white subjects treated for tubercle, individual determinations were made of: a) The power of inactivation of isoniazid. b) The degree of pigmentation (iris, skin, hair) assessed by a weighted pigmented index of the iris. A statistical study of the results shows the clear existence of a narrow positive correlation between these two characters, such that the more pigmented a subject is, the greater is the chance of rapid inactivation of isoniazid. An attempt at a biochemical explanation is proposed. The results in the world literature (Japanese, Swedish, American) are in keeping with these observations. Thus, weakly pigmented tuberculous patients are potentially a new group at risk from anti-TB drugs.

Eye Color↗
PubMed2005

Suppression of progressive loss of coat color in microphthalmia-vitiligo mutant mice.

The coat color of C57BL/6-Mitfvit/vit mice whitens with age, because of a one-nucleotide mutation in the DNA-binding region of the microphthalmia-associated transcription factor (MITF), which plays an important role in melanocyte growth and differentiation. To investigate the signals regulating MITF function, we prepared transgenic mice expressing three of the external signals that are important for melanocyte development, i.e., hepatocyte growth factor (HGF), stem cell factor (SCF), and endothelin-3 (ET3), and crossed these mice with Mitfvit/vit mice. We found that the age-dependent coat color whitening of the Mitfvit/vit mice was completely suppressed by the overexpression of HGF or SCF in the skin, but not by that of ET3. Moreover, HGF, but not ET3, promoted the proliferation of Mitfvit/vit mice-derived melanocytes in culture. These results suggest that the signals from exogenous HGF and SCF rescued the mi-vitiligo mutation and also that ET3 does not stimulate the common signal transduction pathway for MITF activation shared by HGF and SCF.

Age Factors↗
PubMed1976

Observations on the geographic variation and skeletal development of Aotus.

The geographic pattern of coat color and craniometric variation were examined in Aotus. The coat color and pattern permitted recognition of the geographic origin of night monkeys from many parts of Latin America. The geographic pattern of craniometric variation differed from the pattern of phenotypic variation and led the authors to doubt the validity and usefulness of the currently recognized subspecific classification. Tooth eruption and bone ossification were studied in a sample of Aotus skeletons. Tentative criteria were presented for judging the ages of night monkeys by visual examination of their teeth or by x-ray of their teeth or bones.

Animals↗
PubMed1993

Correction of a lysosomal deficiency by contact-mediated enzyme transfer after bone marrow transplantation.

The effectiveness of bone marrow transplantation for treating lysosomal deficiency diseases relies on the ability of bone marrow cells to provide the missing enzyme to various tissues of the recipient. This has been shown to occur in vitro by endocytosis of enzyme secreted by bone marrow-derived cells and also by direct cell-to-cell-contact. To investigate the mechanism of enzyme replacement therapy in vivo we have used, as enzyme donors, bone marrow cells from coat color mouse mutants that secrete very low or very high levels of a lysosomal enzyme, beta-glucuronidase. Our results show that the level of beta-glucuronidase activity acquired by the tissues of recipient, enzyme-deficient mice is not related to the ability of the donor bone marrow-derived cells to secrete the missing enzyme. This finding suggests that cell-to-cell transfer of lysosomal enzymes may play an important role in the correction of lysosomal diseases by bone marrow transplantation.

Alleles↗
PubMed1997

Effects of the nonagouti coat-color allele on behavior of deer mice (Peromyscus maniculatus): a comparison with Norway rats (Rattus norvegicus).

The agouti locus influences coat color by antagonizing melanocyte-stimulating hormone (MSH) at its receptor on pigment cells and may antagonize MSH in neural tissue. This study replicates work on rats to assess whether behavioral (neural) effects of the agouti locus are as similar across mammals as those on coat color. Handling, open-field, platform jump, and food-novelty tests were conducted on agouti and nonagouti deer mice (Peromyscus maniculatus) following protocols in C. A. Cottle and E. O. Price (1987). As with rats, nonagouti deer mice were less aggressive, less active, and easier to handle compared with their agouti counterparts. Nonagouti deer mice also groomed more than agouti subjects. Thus, behavioral effects of the agouti locus are conservative, and agouti may be an important modulator of melanocortins in neural as well as integumentary tissue.

Agouti Signaling Protein↗
PubMed1987

Behavioral and color variations between rat lines developed for differential alcohol sensitivity.

The AT and ANT rat lines, outbred for differential sensitivity to ethanol-induced motor impairment, also show a difference in their sober behavior. It is not manifested in an escapable-shock test or an amphetamine-stress test, but is shown as significantly more activity by the alcohol-insensitive ATs in a low-stress (33 degrees C) modification of the forced-swimming test. The correlation between alcohol sensitivity and swimming-test activity is, however, not significant in unselected Long Evans rats. Differences in coat color have also developed in the AT and ANT lines; it was possible to estimate whether these changes are independent of ethanol sensitivity with computer simulations. They showed, for example, that the probability of the observed loss of the agouti color in the ATs being by chance is about 0.53 and the probability is nearly 0.50 for there being a spurious line difference, i.e., unrelated to ethanol sensitivity, in which only line had lost the agouti allele. More generally, these and other simulations showed that permanently maintaining selected lines is not the optimal method for finding genetically-based factors related to ethanol sensitivity or other characteristics for which lines have been developed. Nor is either revitalization or replicate lines optimal. The best method apparently would be perpetual restarting of lines.

Animals↗
PubMed1992

Unusual accumulation of copper related to induction of metallothionein in the liver of LEC rats.

Copper (Cu), iron (Fe), zinc (Zn) and manganese (Mn) levels in organs of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis, were determined by instrumental neutron activation analysis method. Unusual accumulations of Cu in the liver of LEC rats were found, depending on the age of the animals, the metal concentration being more than approximately 20-40 times those of normal LEA rats (Long-Evans rats with an agouti coat color). Fe and Zn were also accumulated, in addition to Cu, significantly in the LEC rats. The unusual Cu accumulations in the liver of LEC rats were associated with the induction of metallothionein, estimated by radioimmunoassay method, in the liver of LEC rats, rather than that of superoxide dismutase, estimated by electron spin resonance -spin trapping method. These findings suggest that the unusual Cu accumulation in LEC rats is involved in the development of jaundice, hepatic injury and hepatocellular carcinoma.

Aging↗
PubMedDate not supplied

Coat color genetics of Peromyscus: V. California blonde, a new recessive mutation in the deer mouse.

California blonde is a coat color mutation in the deer mouse (Peromyscus maniculatus) discovered among descendants of wild-type animals collected on Santa Cruz Island, California. The phenotype is produced by the presence of brown, rather than black, eumelanin in the pelage and skin. Retinal pigmentation is also reduced. The condition is inherited as an autosomal recessive trait. The California blonde gene is nonallelic with the brown (b), blonde (bln), and platinum (plt) mutant genes in this species. California blonde represents a newly detected genetic locus in the deer mouse. The symbol cfb is provisionally assigned for this genetic locus.

Animals↗
PubMed1991

Developmental interactions in the pigmentary system of the tip of the mouse tail: effects of coat-color genes on the expression of a tail-spotting gene.

The tails of agouti C3H/HeJmsHir mice are completely pigmented, whereas the tails of black C57BL/10JHir animals possess unpigmented tips. Genetic analysis indicates that white tail-tipping is due to an autosomal recessive gene, with incomplete penetrance, that segregates independently from the gene for agouti with a maternal influence in the F1 generation. To analyze the influence of specific coat-color genes on the expression of tail-spotting in mice, five congenic lines of C57BL/10JHir with different coat colors were prepared. No influence was observed on the occurrence of tail-spotting in agouti (A/A) or dilute (d/d) mice or in F1 mice from crosses between black and albino (c/c), or in F1 mice from crosses between black and pink-eyed dilution (p/p). However, the frequency of tail-spotting was dramatically decreased in brown (b/b) mice. These results suggest that the mutant allele (b) at the brown locus is involved in determining the extent of pigmented areas in the tail tips of mice through an interaction with the tail-spotting gene.

Animals↗
PubMed1988

Pigment types in sheep, goats, and llamas.

Pigment types in various colors of fiber from sheep, goats, and llamas were assayed by a method using high performance liquid chromatography. In these three species the black/gray group is due to eumelanin, which is fully intense in all three species. Red phenotypes are due to pheomelanin and fade considerably with age in fiber from sheep and goats, but not in llamas. This phenomenon has implications on the genetic mechanisms used in generating white fiber. Brown phenotypes in sheep are due to eumelanin, in goats these phenotypes are equivocal, and they were not observed in llamas.

Animals↗
PubMed1977

Effect of a coat color locus on kidney lysosomal glycosidases in the house mouse.

Activities of three lysosomal glycosidases, beta-galactosidase, beta-glucuronidase, and N-acetyl-beta-hexosaminidase, have been shown to differ in bf/bf and bf/+ mice. Thus bf/bf mice usually have much higher activities of these enzymes in their kidney cells than bf/+ animals. There seem, however, to be some exceptions to this general pattern, especially for galactosidase of females from the C57BL/6J strain. A likely interpretation of the difference is that the bf locus has pleiotropic effects. An alternative explanation, less likely, is that a gene closely linked to bf is involved. There is also a differential response to dihydrotestosterone in different groups of mice reflected in activity changes of the three enzymes.

Animals↗
PubMed1987

Deficient melanosome formation in some coat-color mutant mice revealed by a monoclonal antibody against melanosome.

Some coat-color loci in mice are considered to control melanosome formation. In order to investigate genetic control of melanosome-associated proteins, we prepared monoclonal antibodies against mouse melanosomes. Melanosomes were isolated from B16 mouse melanoma through differential fractionation. BALB/c mice were immunized with an SDS-solubilized melanosome fraction. The spleen cells were subsequently fused with mouse myeloma cells, the resulting hybridomas cloned. Their secreted IgG was screened for reactivity to the SDS-solubilized melanosome fraction. One monoclonal antibody, M10, was shown to react to melanosomes by immunoelectronmicroscopy. It recognized a single protein band of 61,000 dalton on immunoblots of gel-fractionated melanosomes. The reactivities of M10 to skin homogenates from various coat-color mutants were examined by the ELISA method. Five congenic genotypes, non-agouti (a/a), brown (b/b), albino (c/c), dilute (d/d), and pink-eyed dilution (p/p) were examined. Among these, b/b and p/p showed significantly lower reactivities than a/a. Our results seem to suggest that the pigment abnormalities in these mutants result from abnormalities of the melanosomal proteins. In the case of albino mice, the reactivity of M10 to skin homogenate was almost the same as the wild-type mouse. It seems that the albino mice are capable of producing the melanosomal protein.

Animals↗
PubMed1994

Mutagenicity of 1,3-butadiene inhalation in somatic and germinal cells of mice.

Inhalation exposure of mice to 50, 200, 500 or 1300 ppm of 1,3-butadiene for 6 h per day for 5 consecutive days caused micronuclei in mouse bone marrow and peripheral blood erythrocytes. The dose response was non-linear. The slope of the curve flattened with increasing exposure concentration. Coat color spots were found in the mouse spot test after exposure of pregnant females on pregnancy days 8-12 to 500 ppm of 1,3-butadiene. Dominant lethal mutations were induced in spermatozoa and late spermatids after exposure of male mice to 1300 ppm with the 5-day exposure regimen. Thus, in the mouse 1,3-butadiene is a somatic and germ cell mutagen.

Administration, Inhalation↗