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PubMed1986

Interstrain competition amongst mouse spermatozoa inseminated in various proportions, as affected by the genotype of the Y chromosome.

Nonagouti (KP X C57BL)F1 hybrid females were artificially inseminated with a mixture of spermatozoa from males of the KE (nonagouti) and CBA (agouti) strains and the genotype of young was estimated by fur pigmentation. When KE and CBA spermatozoa mixed in the ratios of 1:1, 2:1 and 4:1 were inseminated after ovulation, 87%, 56% and 29% of progeny, respectively, were sired by CBA males, i.e. proportions of CBA progeny were significantly higher than ratios of CBA spermatozoa in the mixture. The surplus of CBA progeny was significantly less in females inseminated before ovulation, which may suggest that more rapid capacitation of CBA spermatozoa is partly responsible for their competitive advantage. In preparations from oviducal flushings of females killed 2-3 h after insemination, CBA spermatozoa (recognized by their shape) were found in similar proportions as in the inseminated mixture. There was therefore no evidence of their preferential selection at the uterotubal junction. No competitive advantage of CBA spermatozoa occurred when they were inseminated with spermatozoa from males of the KE.CBA strain, congenic with KE but with the Y chromosome derived from the CBA strain. This indicates that genetic factors linked with the Y chromosome may influence competitive ability of spermatozoa.

Animals↗
PubMed1998

Spontaneous testicular regression in collared lemmings (Dicrostonyx groenlandicus) exposed to prolonged long photoperiod.

Reproductive maturation and attainment of maximal gonadal size in collared lemmings (Dicrostonyx groenlandicus) is facilitated by transfer from a short photoperiod (8 h light: 16 h dark) to a long photoperiod (22 h light:2 h dark). However, reproductive maturation in lemmings born in 22 h light:2 h dark is impeded by exposure to the natal photoperiod of 22 h light:2 h dark. Data from adult lemmings suggest that prolonged exposure to a long photoperiod of 20 h light:4 h dark results in gonadal regression. The present experiments were conducted to test the hypothesis that adult lemmings exposed to a prolonged long photoperiod undergo testicular regression. Male collared lemmings were transferred at weaning (19 days of age) from the natal photoperiod of 8 h light:16 h dark to one of two long photoperiods: 22 h light:2 h dark or 24 h light:0 h dark (constant light). Gonadal mass was maximal in both groups 10 weeks after weaning. However, 20 weeks after weaning, gonadal mass in both groups was low (relative to that at 10 weeks), suggesting that regression had occurred. When testes mass was maximal 10 weeks after weaning, animals were transferred in groups from 22 h light:2 h dark to one of several shorter photoperiods: 20 h light:4 h dark, 18 h light:6 h dark, 16 h light:8 h dark, or 8 h light:16 h dark. Testes mass 20 weeks after weaning was greatest, that is, not different from maximal, in animals from the 20 h light:4 h dark and 18 h light:6 h dark groups, intermediate in animals from the 16 h light:8 h dark group, and low in animals from the 8 h light:16 h dark group. These observations indicate that transfer from 22 h light:2 h dark to a slightly shorter photoperiod permits maintenance of gonadal size, but transfer to a short photoperiod causes testicular regression. Body weight, bifid claw width and pelage colour did not change during spontaneous gonadal regression in animals housed in a long photoperiod for 20 weeks. These results suggest that prolonged exposure to an unchanging long photoperiod causes spontaneous testicular regression, and that photoperiod regulates reproductive and somatic parameters independently.

Animals↗
PubMed2004

Heritability and segregation analysis of deafness in U.S. Dalmatians.

Hereditary loss of hearing affects many breeds of the domestic dog, but the Dalmatian has the highest prevalence. Approximately 30% are affected in the United States (U.S.) population. It is widely accepted that a relationship exists between deafness and pigmentation in the dog and also in other animals. While the Dalmatian exemplifies this relationship, the genetic origin and mode of inheritance of deafness in this breed are unknown. The goals of this study were to: (1) estimate the heritability of deafness in an extended kindred of U.S. Dalmatians and (2) determine, through complex segregation analysis, whether there is a major segregating locus that has a large effect on the expression of deafness. A kindred of 266 Dalmatians was assembled, of which 199 had been diagnosed using the brainstem auditory evoked response to determine auditory status. Of these, 74.4% (N = 148) had normal hearing, 18.1% (N = 36) were unilaterally deaf, and 7.5% (N = 15) were bilaterally deaf. A heritability of 0.73 was estimated considering deafness a dichotomous trait and 0.75 considering it as a trichotomous trait. Although deafness in the Dalmatian is clearly heritable, the evidence for the presence of a single major gene affecting the disorder is not persuasive.

Animals↗
PubMed1987

[Biological and hematochemical characteristics of herbivorous common voles (Microtus arvalis Pallas)].

In 1979, some pairs of voles (Microtus arvalis Pallas) were introduced to our laboratory from Hungary. Thereafter, they were successfully bred and increased in number, as experimental small animals for herbivorous domestic animals. They have been raised in a room and fed with pelleted feed for herbivores and chopped hay-cubes. We can change the high-fiber-containing rations from the chopped hay-cube to the alfalfa pellet that is widely available in laboratories. Regarding the breeding characteristics of the voles, the average litter size was 5.44 +/- 1.64, and the age at the first birth was 55.4 +/- 10.7 days. Some voles with white coats were found during the breeding process in our laboratory. Hematochemical characteristics of the voles were determined and the following characteristics were noted. Red blood cell counts of the voles were higher than those of other experimental animals (rat, mouse). White blood cell counts of the voles were lower than those of the other animals. The electrophoretic patterns of serum protein differed markedly from those of other experimental animals. The gamma-globulin concentrations of the voles were very low, and A/G ratios were high. Blood glucose concentrations of the voles were lower than those of the other mono-gastric experimental animals. Activities of serum enzymes (GOT, GPT, ALP) were higher than those of other experimental animals (rat, mouse, cow).

Animal Feed↗
PubMedDate not supplied

Comparison of structural and chemical properties of black and red human hair melanosomes.

Melanosomes in black and red human hair are isolated and characterized by various chemical and physical techniques. Different yields of 4-amino-hydroxyphenolanaline by HI hydrolysis (a marker for pheomelanin) and pyrrole-2,3,5-tricarboxylic acid by KMnO(4)/H(+) oxidation (a marker for eumelanin) indicate that the melanosomes in black hair are eumelanosomes, whereas those in red hair are mainly pheomelanosomes. Atomic force microscopy reveals that eumelanosomes and pheomelanosomes have ellipsoidal and spherical shapes, respectively. Eumelanosomes maintain structural integrity upon extraction from the keratin matrix, whereas pheomelanosomes tend to fall apart. The black-hair eumelanosomes have an average of 14.6 +/- 0.5% amino acids content, which is attributed to the internal proteins entrapped in the melanosomes granules. The red-hair melanosomes contain more than 44% of amino acid content even after extensive proteolytic digestion. This high content of amino acids and the poorly reserved integrity of red-hair melanosomes suggest that some proteins are possibly covalently bonded with the melanin constituents in addition to those that are entrapped inside the melanin species. Soluene solubilization assay indicates the absorbance of melanin per gram of sample, adjusted for the amino acid content, is a factor of 2.9 greater for the black-hair melanosomes than the red-hair melanosomes. Metal analysis reveals significant amounts of diverse heavy metal ions bound to the two types of melanosomes. The amount of Cu(II) and Zn(II) are similar but Fe(III) content is four times higher in the red-hair melanosomes. (13)C solid-state nuclear magnetic resonance spectra and infrared spectra are presented and are shown to be powerful techniques for discerning differences in the amino acid contents, the 5,6-dihydroxyindole-2-carboxylic acid:5,6-dihydroxyindole ratio, and the degree of cross-linking in the pigment. Excellent agreement is observed between these spectral results and the chemical degradation data.

Adult↗
PubMed1986

Melanocyte-stimulating hormone and the regulation of tyrosinase activity in hair follicular melanocytes of the mouse.

Skin tyrosinase activity increases during hair growth in C3H-HeAvy mice and reaches higher levels in young (30- to 35-day-old) mice when the hair follicular melanocytes synthesize the black pigment, eumelanin, than in older (6-month-old) mice when they produce the golden yellow pigment, phaeomelanin. To examine the regulation of the melanocytes at these different stages we have compared the effect of alpha-MSH and other agents that act, through cyclic AMP-dependent mechanisms, on skin tyrosinase activity in both young and old mice during hair growth, initiated by plucking. Daily administration of alpha-MSH, isoprenaline or theophylline increased coat darkness, and skin tyrosinase activity in the younger mice 7-9 days after plucking, but they were ineffective in the older mice. Similarly alpha-MSH, 8-bromo-cyclic AMP or theophylline increased tyrosinase activity in skin explants from the younger mice incubated for up to 24 h but had no effect in explants from older mice. Cyclic GMP had no effect on tyrosinase activity in skin explants from both young and old mice. It is suggested that whereas cyclic AMP-dependent mechanisms may operate to regulate tyrosinase activity in the hair follicular melanocytes of younger mice that produce eumelanin these systems may not operate in the older mice when these melanocytes synthesize phaeomelanin. Phaeomelanin synthesis, unlike that of eumelanin, may not depend upon tyrosinase and its regulation by cyclic AMP and this could explain the low levels of this enzyme in the skin and its failure to respond to alpha-MSH and other activators of the cyclic AMP system during periods of phaeomelanin production.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Effects of melanocyte-stimulating hormone on tyrosinase expression and melanin synthesis in hair follicular melanocytes of the mouse.

Tyrosinase mRNA, synthesis and activity were measured in the skin during the first 2 weeks of life of C3H-HeAvy mice. Tyrosinase mRNA levels were found to peak on days 3-4 and were followed by increases in tyrosinase synthesis and activity which peaked on days 6-7 and 7-8 respectively. These changes in tyrosinase expression were presumably associated with the growth of the first coat of hair that in neonatal C3H-HeAvy mice is yellow in colour as a result of the increased proportion of phaeomelanin. By the time hair growth had ceased there was no expression of tyrosinase at both mRNA and protein levels. Daily administration of alpha-melanocyte stimulating hormone (alpha-MSH) enhanced the expression of tyrosinase mRNA transcripts, tyrosinase synthesis and activity. The increase in tyrosinase activity paralleled the change in the amount of tyrosinase, suggesting that the primary action of alpha-MSH is to stimulate new synthesis of the enzyme. This induction of tyrosinase was associated with the growth of hair that was darker in colour than that of the controls and contained an increased proportion of eumelanin. This increase in eumelanin reflected a decrease in phaeomelanin content. It was concluded that, through its actions on the enzyme tyrosinase, alpha-MSH is able to switch the synthesis of phaeomelanin to that of eumelanin in hair follicular melanocytes.

Animals↗
PubMed2005

Skin aging: a role for telomerase and telomere dynamics?

Skin is a complex tissue composed of two very different compartments -- the continuously renewing epidermis made up mostly by keratinocytes and the underlying matrix-rich dermis with the resting fibroblasts as its major cellular components. Both compartments are tightly interconnected and a paracrine mutual interaction is essential for epidermal growth, differentiation, and tissue homeostasis. Skin aging is commonly viewed as wrinkle formation, hair greying, and impaired wound healing. Nevertheless, the epidermis as the outermost shield needs to remain intact in order to guarantee an inside-out and outside-in barrier function throughout life time of a human being. Furthermore, the epidermis is one of the few regenerative tissues that express telomerase, the ribonucleoprotein complex that can counteract telomere erosion, one of the presently mostly favoured potential mechanisms causing cellular aging. This raises the question whether in the epidermis telomerase is able to counteract telomere erosion and thereby to prevents a telomere-dependent aging process and consequently which part of the skin is responsible for the most obvious changes associated with skin aging.

Animals↗
PubMed1993

Comparative evaluation of scalp hair by phototrichogram and unit area trichogram analysis within the same subjects.

Quantitative evaluation of scalp hair requires techniques that are reproducible. The unit area trichogram is such a method but is unsuitable for large-scale clinical trials. An alternative may be the phototrichogram--a non-plucking, non-invasive method. Hair variables were evaluated in 12 Caucasian subjects employing both methods. The mean value for total hair density was significantly underestimated by the phototrichogram (181 versus 237 hairs/cm2); however, no significant difference was found between this phototrichogram value and the number of non-vellus hairs/cm2. Estimates for the percentage of anagen hairs were similar with both methods. Hair diameters from the phototrichogram were too unreliable to be of any practical use. Analysis of the individual hair data revealed that light hair was much more difficult to evaluate than dark hair. Consequently, Caucasian subjects with light hair or dark skin subjects with dark hair should be excluded from studies employing phototrichograms.

Adult↗
PubMed1982

Effects of supplemental dietary copper on growth, reproductive performance and kit survival of standard dark mink and the acute toxicity of copper to mink.

Natural dark mink kit were fed a diet supplemented with 0, 25, 50, 100 or 200 ppm Cu from CuSO4 . 5H2O for 153 or 357 d. The shorter term Cu supplementation had no significant beneficial or adverse effects on mink body weight gains or hemoglobin or hematocrit concentrations, although plasma Cu concentrations were slightly elevated in the mink fed added Cu. Liver Cu concentrations were significantly increased only in the mink fed 200 ppm Cu. Liver Zn and Fe concentrations were not affected by the added Cu. Darker fur was observed in pelted males fed the higher levels of Cu. The reproductive performance of mink on the longer term Cu supplementation was not adversely affected, although greater kit mortality and reduced "litter mass" were a result of the higher Cu concentrations. The acute (21-d) ip LD50 concentrations of Cu sulfate and Cu acetate in adult mink were 7.5 and 5.0 mg/kg, respectively.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Equine melanoma in a population of 296 grey Lipizzaner horses.

REASONS FOR PERFORMING STUDY: Equine melanomas occur most commonly in grey horses at age 5 years or more. Generally, benign and malignant melanomas are distinguished by microscopy, but a more distinct classification would be helpful. OBJECTIVES: The objectives of this study were to gain further evidence concerning the occurrence of melanotic tumours, and to evaluate the impact of heredity on melanoma development. METHODS: A clinical study was conducted on a defined population of 296 grey horses of Lipizzaner breed. Individuals were classified according to their stage of disease using a 0-5 scale. Heritability was estimated on a sample of 296 grey horses with pedigrees traced back as far as 32 generations. RESULTS: Of the 296 horses, dermal melanomas were present in 148 horses (50%), 68 of which were more than age 15 years; 51 of these were melanoma-bearing. In 75.6% of cases, melanotic tumours were detected underneath the tail. Although melanoma-bearing grey horses were encountered up to stage 4, none of the affected individuals suffered any severe clinical effect or was handicapped in performance. Statistical analysis revealed highly significant effects of stud and age (P < 0.0001), explaining 28% of the total variability. CONCLUSIONS: In contrast to melanomas in solid-coloured horses characterised by early metastases, melanomas in grey horses showed less malignancy. Affected individuals often had encapsulated nodules or structures similar to human blue nevi. Grey horse-specific genetic factors inhibiting metastatic processes may be responsible for this phenomenon. POTENTIAL CLINICAL RELEVANCE: Although the obtained heritability estimate of 0.36 with a standard error of 0.11 indicates a strong genetic impact on the development of melanoma in ageing grey horses, a possible influence of the genes with large effects was also suggested. Therefore, further analysis is required of melanoma development in the ageing grey horse.

Age Distribution↗
PubMed1984

Flash induced nystagmus (FIN) in the rabbit: input-output relations.

Flash-induced nystagmus (FIN) was elicited by monocular flicker-stimulation at 20-40 Hz. It was found more often in albino than in pigmented rabbits. Slow phase velocity (SPV) showed a gradual increase, then a steady-state level in most animals and an after-response after cessation of stimulation. incremental and decremental phase mainly showed an exponential change in SPV. Apparent time constants were in the range of 5-40 sec. Simultaneous recording of both eyes revealed greater velocity and amplitude of both phases of FIN in the stimulated eye. FIN can be specified as a type of nystagmus that is evoked by monocular essentially open-loop stimulation of the crossed ("subcortical") visual pathway. Direction-selective elements in the retina may play a specific role and their predominant orientation gives rise to nystagmus in adducting direction in the flicker-stimulated eye as if it were exposed to optokinetic stimulation in the temporonasal direction.

Animals↗
PubMed1994

Ambilaterality: definition from handedness preference questionnaires and potential significance.

Defining handedness according to the results of preference questionnaires is operational. Most often, handedness is defined according to the extremes of the handedness range or equal divisions of the entire handedness range. These definitions may exclude ambilateral (ambidextrous) subjects from analysis or may fail to separate out subjects with intermediate handedness scores. Examples from the literature are presented to show that subjects with handedness scores in the weak right-handedness range may have characteristics that distinguish them from subjects in other segments of the handedness spectrum. Handedness studies should assess the middle handedness range using a scoring method which identifies subjects in this range.

Diethylstilbestrol↗
PubMed1983

Morphologic and phenotypic analysis of an outcross line of blotchy mouse.

Blotchy is an X-linked recessive mutation at the "Mottled" locus in the mouse. The affected blotchy male (Blo/Y) mouse from an inbred genetic background demonstrates morphologic and physiologic abnormalities consistent with emphysema in adult life. Breeding of Blo/Y mice has been difficult because the inbred Blo/Y males are sterile. We report the successful development of a line of outbred Blo/Y male and Blo/Blo female nice by the controlled outcross mating of the inbred heterozygous Blo/+ female with the Argonne hybrid B6CF1 male mouse. The subsequent outcross Blo/Y progeny breed vigorously with the outcrossed Blo/+ female. The lungs of the outbred Blo/Blo female and inbred Blo/Y male mice demonstrate mild to moderate panacinar emphysema with a significant decrease in internal surface area (p less than 0.005) and an increase in mean linear intercept (p less than 0.005). In contrast, the lungs of the outbred Blo/Y is structurally normal. Despite the absence of emphysema-like changes in the outbred Blo/Y males, there were phenotypic features that suggest inherited abnormalities in connective tissue proteins including 1) high incidence of aortitis leading to premature death from aneurysmal rupture, and 2) significant decrease in the morphometrically determined parenchymal elastic fiber length in the lung (p less than 0.01). The outbred blotchy strain may be a useful experimental animal model in determining the pathogenesis of emphysema.

Animals↗