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At least 613 records · Page 34Linked to original sources
PubMed1988

Histocompatibility antigen changes associated with pink-eyed dilute (p) mutations.

The tight linkage between the H-4 histocompatibility locus and the pink-eyed dilute (p) locus raises the possibility that a single gene is responsible for both a histocompatibility antigen and coat color phenotype. To examine this possibility, we have investigated the effects of a spontaneous coat color mutation, pink-eyed unstable (pun), which occurred at the p locus in the C57BL/6J inbred strain, on histocompatibility antigen phenotype. Skin grafts were transplanted from two independently maintained B6-pun substrains to coisogenic, wild-type C57BL/6 recipients; graft rejection uniformly commenced at 6-7 weeks but did not culminate in complete graft destruction as observed in other cases of "crisis" rejection. Neither the onset of rejection time nor the intensity of rejection could be accelerated by introducing new H-2 haplotypes into the wild-type recipients. These results suggested that the pun allele was associated with a histocompatibility antigen not shared with C57BL/6. The pun allele is characterized by a relatively high frequency of reversion to wild-type. Therefore, skin grafts from B6-pun donors were transplanted to homozygous, revertant (+/+) recipients which were subline-matched with the donors; these grafts underwent crisis rejection with the same time of onset of rejection as observed with C57BL/6 recipients. These observations indicate that a new histocompatibility antigen is associated with the pun mutation and is lost upon reversion to wild type; this association is the first demonstration of a link between histocompatibility and coat color phenotypes.

Animals↗
PubMed2006

A golden age of human pigmentation genetics.

The zebrafish golden mutation is characterized by the production of small and irregular-shaped melanin granules, resulting in a lightening of the pigmented lateral stripes of the animal. The recent positional cloning and localization of the golden gene, combined with genotype-phenotype correlations of alleles of its human orthologue (SLC24A5) in African-American and African-Caribbean populations, provide insights into the genetic and molecular basis of human skin colour. SLC24A5 promotes melanin deposition through maturation of the melanosome, highlighting the importance of ion-exchange in the function of this organelle.

Animals↗
PubMed1994

Mutations in the murine homologue of the Menkes gene in dappled and blotchy mice.

The murine homologue of the Menkes disease gene (MNK) was isolated from cDNA libraries, using human cDNA clones as probes, and by PCR. The predicted amino acid sequence shows a high level of identity (89.9%) with the human protein, and the predicted functional domains in the human protein are present. Using probes to the mouse Mnk gene, we found that the mottled dappled mutation was caused by alteration in the Mnk locus and lack of expression of Mnk RNA. Tissues of the blotchy mouse contained two larger sizes of MNK mRNA demonstrating a likely defect in RNA splicing. Thus, the mottled locus is homologous to the human MNK locus and dappled and blotchy are allelic mutations in this gene.

Adenosine Triphosphatases↗
PubMed1992

Expression of tyrosinase gene in transgenic albino mice: the heritable patterned coat colors.

To elucidate the regulatory mechanism for tyrosinase gene expression in vivo, we microinjected a mouse tyrosinase minigene, mg-Tyrs-J, into the fertilized eggs of BALB/c albino mice. As a result, we obtained six pigmented founder mice that exhibited non-standard coat color variations as well as the wild-type phenotype. These founder mice were subsequently crossed with BALB/c albino mice to establish the transgenic lines. As a consequence, two primary lines and five sublines have been obtained from four of the six founder mice. We found that not only uniformly pigmented phenotypes but also patterned phenotypes were inherited by their descendants. The possible underlying mechanism of the patterned phenotypes is discussed.

Albinism↗
PubMedDate not supplied

Variation of the amide I and amide II peak absorbance ratio in human hair as measured by Fourier transform infrared spectroscopy.

Human scalp hair samples were examined by Fourier transform infrared spectroscopy and the ratio of the amide I to amide II band absorbances was determined. The effects of hair oxidation, color, age of sample, and sex of source were examined. Scalp hair from 98 individuals was also analyzed. While there were differences in the amide absorption band ratios, these were difficult to relate to the individualization of the hair samples and did not appear to have a sufficient discriminatory value for routine forensic use.

Adolescent↗
PubMed2004

Influence of antioxidants on the sun protection properties of hair care products.

Aim of this study was to determine the influence of commercially available antioxidants on sun protection properties of hair care products. To evaluate changes of human hair L*a*b-color measurements, tensile strength measurements and high pressure dynamic scanning calorimetry (HPDSC) measurements were carried out. To have a measure for the concentration of the activity of the reactive species, causing hair or color damage, chemiluminescence measurements were carried out. Before the test with the antioxidants experiments were carried out to evaluate effects of varied artificial weathering conditions on physical properties of hair. Here high relative humidity (85%) and low radiant flux (600W/m2) exhibited the biggest changes in natural hair color but the lowest changes in the in tensile strength and HPDSC measurements. All of the tested antioxidants reduced the chemiluminescence level when used in a pre-sun or after-sun formulation. According to the HPDSC measurements the antioxidants showed a slight increase of the peak temperature and therewith a hint towards a protection effect when used in a pre-sun or after-sun product. In contrast thereto some of the antioxidants reduced the tensile strength of sun care products for hair when added. A slight reduction in the lightening of natural hair color could be observed when antioxidants were present in the sun care formulations. The effect of antioxidants in sun care formulations used on dyed hair was strongly dependent on the shade of hair. The addition of some antioxidants yielded significant improvements of the protection properties of the used sun care product in some measurement methods.

Antioxidants↗
PubMed1990

The recovery from ultraviolet radiation-induced erythema and melanoma risk factors: a case-control study.

The proportion of subjects recovering from skin erythema induced by a single ultraviolet radiation challenge of 6 times the minimal erythema dose during a 3-week period was lower in 47 patients with stage I cutaneous melanoma than in 48 healthy control subjects with similar risk factors of increased sensitivity to ultraviolet radiation (p = 0.045). This difference indicates that the patients with melanoma were more susceptible to prolonged ultraviolet radiation-induced skin damage than the control subjects. Prolonged erythema response was significantly associated in the melanoma group with decreased minimal erythema doses (odds ratio [OR] = 11.3) and with the presence of freckles (OR = 5.5), and was associated in the control group with light eye color (OR = 5.8). Prolonged ultraviolet radiation-induced erythema is neither a unique feature of melanoma patients nor a useful marker for identifying risk groups for cutaneous melanoma.

Adult↗
PubMed2005

Allele variations in the OCA2 gene (pink-eyed-dilution locus) are associated with genetic susceptibility to melanoma.

The occuloalbinism 2 (OCA2) gene, localized at 15q11, encodes a melanosomal transmembrane protein that is involved in the most common form of human occulo-cutaneous albinism, a human genetic disorder characterized by fair pigmentation and susceptibility to skin cancer. We wondered whether allele variations at this locus could influence susceptibility to malignant melanoma (MM). In all, 10 intragenic single-nucleotide polymorphisms (SNPs) were genotyped in 113 patients with melanomas and in 105 Caucasian control subjects with no personal or family history of skin cancer. By comparing allelic distribution between cases and controls, we show that MM and OCA2 are associated (p value=0.030 after correction for multiple testing). Then, a recently developed strategy, the 'combination test' enabled us to show that a combination formed by two SNPs was most strongly associated to MM, suggesting a possible interaction between intragenic SNPs. In addition, the role of OCA2 on MM risk was also detected using a logistic model taking into account the presence of variants of the melanocortin 1 receptor gene (MC1R, a key pigmentation gene) and all pigmentation characteristics as melanoma risk factors. Our data demonstrate that a second pigmentation gene, in addition to MC1R, is involved in genetic susceptibility to melanoma.

Adult↗
PubMed1988

Evidence that the effector mechanism of skin allograft rejection is antigen-specific.

In vivo rejection responses are initiated by specific T-cell recognition of foreign histocompatibility antigens expressed by tissue allografts, but it is not certain if the effector mechanism mediating the actual tissue injury is also antigen-specific. To directly assess the specificity of the effector phase of in vivo rejection responses, we constructed B6 in equilibrium with A/J allophenic mice that are genetic mosaics whose individual cells express either H-2b or H-2a histocompatibility antigens but not both. Trunk skin from B6 in equilibrium with A/J allophenic mice was grafted onto immunoincompetent H-2b nude mice and allowed to heal and regrow hair that was both black and white, reflecting the genetic mosaicism of the allophenic grafts. One month after engraftment, the H-2b nude animals were reconstituted with syngeneic H-2b T cells reactive against H-2a allodeterminants. An obvious rejection response ensued involving antigen-nonspecific inflammatory destruction of the epidermis and complete hair loss. Despite the intensity of the nonspecific inflammatory response, the allophenic skin grafts survived. Importantly, the allophenic grafts regrew hair and the predominant color of that hair was black, providing visual proof that syngeneic B6 melanocytes and hair follicle cells had not been destroyed. Thus, these results demonstrate that although the intense inflammatory component of skin graft rejection responses is capable of damaging superficial epidermal cells nonspecifically, it does not cause rejection of skin allografts. Rather, rejection of skin allografts is mediated by antigen-specific effector T cells that assess individual cells within the dermis of the graft for expression of foreign histocompatibility antigens.

Animals↗
PubMed2002

Increased frequency of DNA deletions in pink-eyed unstable mice carrying a mutation in the Werner syndrome gene homologue.

Werner syndrome (WS) is a rare autosomal recessive disorder characterized by genomic instability and the premature onset of a number of age-related diseases, including cancers. Accumulating evidence indicates that the WS gene product is involved in resolving aberrant DNA structures that may arise during the process of DNA replication and/or transcription. To estimate the frequency of DNA deletions directly in the skin of mouse embryos, mice with a deletion of part of the murine WRN helicase domain were created. These mutant mice were then crossed to the pink-eyed unstable animals, which have a 70 kb internal duplication at the pink-eyed dilution (p) gene. This report indicates that the frequency of deletion of the duplicated sequence at the p locus is elevated in mice with a mutation in the WRN allele when compared with wild-type mice. In addition, the inhibitor of topoisomerase I camptothecin also increases the frequency of deletion at the p locus. This frequency is even more elevated in WRN mutant mice treated with camptothecin. In contrast, while the inhibition of poly(ADP-ribose) polymerase (PARP) activity by 3-aminobenzamide increases the frequency of DNA deletion, mutant WRN mice are not significantly more sensitive to the inhibition of PARP activity than wild-type animals.

Animals↗
PubMed2003

Retinal spectral sensitivity, fur coloration, and urine reflectance in the genus octodon (rodentia): implications for visual ecology.

PURPOSE: To determine the eye's spectral sensitivity in three species of the genus Octodon (order Rodentia; infraorder Caviomorpha), O. degus, O. bridgesi, and O. lunatus, as well as the spectral properties of the animals' fur and urine and of objects in their habitat. The genus is endemic in Chile and contains species with different habitats and circadian patterns (diurnal versus nocturnal). METHODS: The electroretinogram (ERG) was used to record scotopic and photopic spectral sensitivity. The reflectance of ventral and dorsal body parts, urine, and other objects from the natural microhabitat were measured with a fiber-optic spectrometer. RESULTS: In scotopic conditions, the maxima of sensitivity (lambda(max)) were at 505.7 +/- 7.7 nm in O. degus, 501 +/- 7.4 nm in O. bridgesi, and 510.1 +/- 7.4 nm in O. lunatus, representing the rod mechanism. In photopic conditions, only the diurnal species O. degus (common degu) was studied. The degu's photopic sensitivity had a lambda(max) at 500.6 +/- 1.2 nm and contained two cone mechanisms with lambda(max) at 500 nm (green, medium-wavelength-sensitive [M] cones) and approximately 360 nm (ultraviolet, short-wavelength-sensitive [S] cones). In all three Octodon species, dorsal body parts were more cryptically colored than ventral ones, and ventral body parts had a significant UV reflectance. The fresh urine of O. degus, used for scent marking in various behavioral patterns, was also high in UV reflectance. CONCLUSIONS: It is suggested that territorial urine marks are visual as well as pheromone cues for UV-sensitive species and hence may have favored the evolution of UV-cones in rodents.

Animal Communication↗
PubMedDate not supplied

Gene-environment interaction in melanoma.

Gene-environment interaction can be defined as a different effect of an environmental exposure in people with different genotypes, or a different effect of a genotype in people with different histories of environmental exposure. Interaction applies when one stratum (high risk) responds differently to an exposure (sun) than another stratum (low risk). Genetic predisposition would appear to be a very important modifier of risk. This paper discusses the concept of gene-environment interaction applied to cutaneous melanoma through discussion of highly penetrant genes and their interaction with sun exposure, through discussion of low penetrant genes and their interaction with sun exposure, and by suggesting a new model for investigation of gene-environment interaction in melanoma. It is stressed that this area of investigation is extremely early in its development.

Cell Cycle↗