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PubMedDate not supplied

Allocare, predation risk, social structure and natal coat colour in anthropoid primates.

Many primate species have a natal coat coloured differently from the coat colour of adults and, in some cases, the natal coat is very different from that of older animals with the infant being conspicuous and/or brightly coloured. This study uses data from 82 anthropoid species to investigate possible correlates of conspicuous natal coat colour (CNC), using comparative, phylogenetically controlled analyses. Five hypotheses were tested using statistical tests on both species data and phylogenetically controlled data. The analyses show some support for the hypothesis that CNCs have evolved to promote allocare but the degree of CNC does not correlate with predation rates, arboreality, or relative testes size.

Adaptation, Physiological↗
PubMed2001

Localization of a recessive juvenile cataract mutation to proximal chromosome 7 in mice.

OBJECTIVE: To localize the chromosomal position of a novel cataract mutation (juvenile recessive cataract; jrc) in mice. METHODS: A mapping population was developed by crossing cataract males (albino MH) to wild-type females (black C57BL/6J). F1 females were backcrossed to albino MH males with cataracts. RESULTS: The results were consistent with a model of a single autosomal recessive gene [153 cataract, 169 wild-type; chi2 = 0.8, 1 degree of freedom (d.f.), p > 0.35]. Linkage with the albino (tyrosinase; Tyr) locus was evident (chi2 = 61.5, 1 d.f., p < 0.0001), implicating chromosome 7 as the location of jrc. Recombination percentages (+/- SE) between jrc and D7Mit340 (1.2 cM location), D7Mit227 (16.0 cM) and D7Mit270 (18.0 cM) were 17.1 +/- 2.1, 3.7 +/- 1.1 and 6.2 +/- 1.3%, respectively. Multi-point mapping determined that the most likely order of these loci is D7Mit340 - jrc - D7Mit227 - D7Mit270 - Tyr. Although animals with the mutant phenotype appeared to have little or no sense of sight, their growth was not different (p >0.20) from that of normal mice. CONCLUSION: The jrc mutation model may be useful in the study of the genetics of cataracts in other animal species, including humans.

Animals↗
PubMed1978

Development of behavior in Lemur macaco in the first nineteen weeks.

Eight young Lemur macaco were observed in a zoo during the first 19 weeks of life. Data were obtained on general motor development, development of independence from the mother, contributions of mothers and young to thhe maintenance of proximity, nursing, grooming, relations between twins, play, feeding, sexual dichromatism, and communication. The results are compared with similar data from other prosimians and from anthropoid primates, and some suggestions made about the evolutionary and adaptive significance of certain aspects of L. macaco development.

Agonistic Behavior↗
PubMed1996

Riverine barriers and gene flow in Amazonian saddle-back tamarins.

We describe patterns of genotypic and phenotypic variation in saddle-back tamarin (Saguinus fuscicollis) populations along the central and upper Rio Juruá, western Brazilian Amazonia. The genetic data are sequence haplotypes of the mitochondrial cytochrome b gene; phenotypic data are pelage colour variants that define sharply demarcated subspecies of this extremely variable tamarin species. We show that gene flow occurs between adjacent subspecies, but that this phenomenon is restricted to the headwater section of the river, which is consistent with expectations from the riverine barrier hypothesis. In this model, the major first-order tributaries of the Amazon form effective barriers to dispersal, with between-bank gene flow limited to the narrowed sections of headwater streams and parallel divergence increasing along both banks from the headwaters to the mouth of a given river. In meandering rivers such as the Rio Juruá, we suggest passive transfer through river channel dynamics as the main mechanism permitting genetic contact between populations on opposite banks of the river. Finally, we argue that in the case of plant and animal species that are largely restricted to unflooded (terra firme) forests, such as tamarins, seasonally flooded (várzea) forest can operate as a critical additional barrier to between-bank gene flow.

Animals↗
PubMed1991

Malignant melanoma in southern Germany: different predictive value of risk factors for melanoma subtypes.

The presented case-control study with 204 melanoma patients and 200 control persons assesses the significance of melanoma risk factors for an ethnically homogeneous population from a geographically small region. In a multivariate analysis of the data the total number of benign naevi proved to be the most predictive parameter with a relative risk (RR) of 14.9 (total number of naevi higher than 50). The constitutional factors red hair colour and skin type 1 were less predictive with an RR of 2.9 and 4.9, respectively. Occupational and recreational sun exposure were of ancillary importance (RR 1.8 and 2.1). The assessment of the risk for the subtypes of melanoma however showed a clear difference in the predictive value of the mentioned risk factors. The risk of developing superficial spreading melanoma is nearly exclusively defined by the number of benign naevi (RR 24.8), red hair colour was of subordinate importance (RR 4.2), whereas the risk of lentigo maligna melanoma is dependent on skin type 1 (RR 12.9) and sun exposure (RR 3.4).

Case-Control Studies↗
PubMed1995

Intracameral ascorbic acid, glutathione and protein levels in albino and pigmented rabbits.

We performed a comparative investigation into differences between albino and pigmented rabbits in respect of intracameral concentrations of ascorbic acid, glutathione and total protein with high-performance liquid chromatography. The intracameral concentrations of reduced ascorbic acid, total ascorbic acid, reduced glutathione, total glutathione and protein in albino rabbits were similar (p > 0.05) to those in pigmented rabbits.

Animals↗
PubMed1977

Hereditary deafness in the cat. Free amino acid and sugar content in the perilymph.

The free amino acid and sugar content of cat perilymph was studied from 11 normal and 17 deaf ears, and compared with simultaneous estimations from cerebrospinal fluid and serum. Each fluid has a distinctive amino acid composition, whilst glucose was the only saccharide demonstrable. The functional status of the cochlea did not influence the biochemical parameters studied.

Amino Acids↗
PubMed1998

Tumor immunity and autoimmunity induced by immunization with homologous DNA.

The immune system can recognize self antigens expressed by cancer cells. Differentiation antigens are prototypes of these self antigens, being expressed by cancer cells and their normal cell counterparts. The tyrosinase family proteins are well characterized differentiation antigens recognized by antibodies and T cells of patients with melanoma. However, immune tolerance may prevent immunity directed against these antigens. Immunity to the brown locus protein, gp75/ tyrosinase-related protein-1, was investigated in a syngeneic mouse model. C57BL/6 mice, which are tolerant to gp75, generated autoantibodies against gp75 after immunization with DNA encoding human gp75 but not syngeneic mouse gp75. Priming with human gp75 DNA broke tolerance to mouse gp75. Immunity against mouse gp75 provided significant tumor protection. Manifestations of autoimmunity were observed, characterized by coat depigmentation. Rejection of tumor challenge required CD4(+) and NK1.1(+) cells and Fc receptor gamma-chain, but depigmentation did not require these components. Thus, immunization with homologous DNA broke tolerance against mouse gp75, possibly by providing help from CD4(+) T cells. Mechanisms required for tumor protection were not necessary for autoimmunity, demonstrating that tumor immunity can be uncoupled from autoimmune manifestations.

Animals↗
PubMed1978

Premature hair graying: a probable coronary risk factor.

Hypertension, diabetes mellitus, hypercholesterolemia, and smoking are known coronary risk factors. It has been our impression that premature graying of the hair also predisposes individuals to myocardial infarctions. To test this hypothesis, we evaluated all of the patients under the age of 50 who were admitted to the coronary care unit between 1974 and 1976 with a proven diagnosis of a myocardial infarction. There were 50 patients. Thirty-eight did not have premature graying. Twelve of the male patients (24%) had virtual total graying of the hair which made them appear older than their stated age. The graying in these patients started on the average at 29 years. Five of these patients state that other family members had premature hair graying. The incidence of diabetes, hypertension, and smoking was similar in those with and without premature hair graying. This preliminary study suggests that premature graying of the hair is associated with premature cardiovascular disease. It should probably be regarded as a coronary risk factor and used to identify patients at increased risk.

Adult↗
PubMed1999

Impact of a sun awareness curriculum on medical students' knowledge, attitudes, and behaviour.

BACKGROUND: Physicians teach sun awareness to their patients, but frequently have no formal training in this area. A week-long dermatology curriculum during Sun Awareness Week that included skin cancer and sun awareness education to first-year medical students was introduced in May 1998 at the University of Western Ontario, London, Canada. OBJECTIVE: The purpose of this study was to determine the baseline knowledge, attitudes, and behaviour of the first-year medical students towards sun awareness before and after the new curriculum. METHOD: This study used a pre- and post-test design to determine the impact of the curriculum on the medical students' knowledge, attitudes, and intent to change behaviour. It also reports any influence of demographic variables on these parameters. RESULTS: The students demonstrated a substantial improvement in their knowledge of sun-related topics despite some baseline knowledge. Many students reported unhealthy behaviour prior to the curriculum, but demonstrated an intent to adopt more healthy behaviour after the curriculum. Minor differences in knowledge and behaviour due to demographic characteristics disappeared upon completion of the curriculum. CONCLUSIONS: An undergraduate medical curriculum with skin cancer and sun awareness education can improve the medical students' knowledge, attitudes, and behaviour towards sun awareness.

Adult↗
PubMedDate not supplied

A possible dominant white gene in Jersey cattle.

A white heifer ("Snow") was born in 1991 from coloured registered Jersey parents. She produced six calves sired by coloured Jersey bulls: three white bull calves, two white heifer calves, and one coloured bull calf. One of the white bull calves was mated with 40 Hereford x Friesian yearling heifers (white face, predominantly black body with some white patches). The 38 resulting calves included 16 white and 22 coloured calves. Twelve of the 16 white calves were heifers and four were bulls. Red or black spotting was recorded on some white calves. The results are consistent with an autosomal dominant mutant causing the white phenotype. The mutation appears to have arisen spontaneously in Snow, then passing to her white progeny and white grand-progeny. The white individuals varied from entirely white in a few cases, to most having some residual small areas of red or black pigmentation in patterns not typical of other reported white spotting patterns of cattle.

Animals↗
PubMedDate not supplied

A mutation in the MATP gene causes the cream coat colour in the horse.

In horses, basic colours such as bay or chestnut may be partially diluted to buckskin and palomino, or extremely diluted to cream, a nearly white colour with pink skin and blue eyes. This dilution is expected to be controlled by one gene and we used both candidate gene and positional cloning strategies to identify the "cream mutation". A horse panel including reference colours was established and typed for different markers within or in the neighbourhood of two candidate genes. Our data suggest that the causal mutation, a G to A transition, is localised in exon 2 of the MATP gene leading to an aspartic acid to asparagine substitution in the encoded protein. This conserved mutation was also described in mice and humans, but not in medaka.

Animals↗
PubMed2002

Rapid degradation of dominant-negative Rab27 proteins in vivo precludes their use in transgenic mouse models.

BACKGROUND: Transgenic mice have proven to be a powerful system to study normal and pathological gene functions. Here we describe an attempt to generate a transgenic mouse model for choroideremia (CHM), a slow-onset X-linked retinal degeneration caused by mutations in the Rab Escort Protein-1 (REP1) gene. REP1 is part of the Rab geranylgeranylation machinery, a modification that is essential for Rab function in membrane traffic. The loss of REP1 in CHM patients may trigger retinal degeneration through its effects on Rab proteins. We have previously reported that Rab27a is the Rab most affected in CHM lymphoblasts and hypothesised that the selective dysfunction of Rab27a (and possibly a few other Rab GTPases) plays an essential role in the retinal degenerative process. RESULTS: To investigate this hypothesis, we generated several lines of dominant-negative, constitutively-active and wild-type Rab27a (and Rab27b) transgenic mice whose expression was driven either by the pigment cell-specific tyrosinase promoter or the ubiquitous beta-actin promoter. High levels of mRNA and protein were observed in transgenic lines expressing wild-type or constitutively active Rab27a and Rab27b. However, only modest levels of transgenic protein were expressed. Pulse-chase experiments suggest that the dominant-negative proteins, but not the constitutively-active or wild type proteins, are rapidly degraded. Consistently, no significant phenotype was observed in our transgenic lines. Coat-colour was normal, indicating normal Rab27a activity. Retinal function as determined by fundoscopy, angiography, electroretinography and histology was also normal. CONCLUSIONS: We suggest that the instability of the dominant-negative mutant Rab27 proteins in vivo precludes the use of this approach to generate mouse models of disease caused by Rab27 GTPases.

Animals↗