Cathleen R. Nichols

Heritability and phenotypic correlations of behaviour and dominance rank of Japanese quail

The frequency and heritability of 13 behavioural acts of hatchling Japanese quail,Coturnix japonica, were measured in a laboratory experiment to examine their relationship to juvenile and adult dominance. The heritability of similar acts in adult quail were also quantified to determine how heritability estimates changed with age. Juvenile dominance rank, determined by frequency of winning conflicts, was uncorrelated with the frequency of any hatchling behaviour or hatchling body size but contained significant additive genetic variance in both males and females. Dominance rank in adult females, measured similarly, also had a high heritability estimate. Dominance in adult males, measured as frequency of initiating a fight and frequency of mounting, had only low heritability. Dominance ranking in adults was uncorrelated with the dominance ranking of juveniles. Dominance may be heritable but may not respond to natural selection because of the interaction between the genotype and the environment.

Increased heat shock protein expression after stress in Japanese quail.

Heat shock proteins (HSPs) have been shown to provide information on the biological impact of environmental stress to organisms, yet none have investigated the HSP response to stress in birds. Japanese quail were exposed to seven different stressors (mild restraint, loud noise, inescapable irritation, cold temperature, isolation in darkness, and two stressful social situations) and expression of HSP30, 60, 70, and 90 in heart, liver, lung, kidney and gonads was examined. Tonic Immobility (TI) tests were also conducted to assess whether the stressors increased fear response. Increased expression of HSP70 was found in the myocardial tissue of birds exposed to loud noise, inescapable irritation, cold temperature, and isolation in darkness. Increased expression of other HSPs was not apparent in the heart or any of the other all tissues examined. Longer TI was observed only in birds exposed to the noise stress. Evidence is presented that a fairly wide range of stressors caused increased expression of HSP70 in the Japanese quail myocardial tissue and that HSPs may provide useful biomarkers for the study of environmental stress in birds.

Dietary cholesterol-induced xanthomatosis in atherosclerosis-susceptible Japanese quail (Cotunix japonica)

Japanese quail of a strain (SUS) susceptible to dietary cholesterol-induced atherosclerosis were fed a diet supplemented with cholesterol (0.5% w/w) for 4, 8 or 12 weeks. Plasma cholesterol increased significantly from 240-1550 mg/dl at 4 weeks and remained at that concentration for 8 and 12 weeks on the same diet. Plasma triglycerides (TGs) increased from 112-384 mg/dl after 4 weeks but showed no significant increases thereafter. Striking eruptive xanthomatous lesions were noticed on the feet of 50% of these birds at 4 weeks, and the percentage of birds affected increased to 85 after 12 weeks on the cholesterol-supplemented diet. This is the first report of xanthomatosis in birds. These birds had also developed atherosclerotic plaques in the aorta and brachiocephalic arteries by 4 weeks. There was no significant correlation between xanthoma scores and plasma cholesterol and TG concentrations at any of the three sampling periods (4, 8 and 12 weeks of cholesterol feeding). There was, however, a significant negative correlation (r = -0.61) between xanthoma scores and atherosclerotic plaque scores at 4 weeks. The correlation became non-significant at later stages of cholesterol exposure. Similarities between mammalian and SUS Japanese quail xanthomatosis may make the SUS quail a useful model for the study of this disorder.

Alterations in aortic antioxidant components in an experimental model of atherosclerosis: a time-course study.

Antioxidant component alterations in the aorta during atherogenesis were examined in atherosclerosis-susceptible (SUS) Japanese quail fed a cholesterol-supplemented (0.5% w/w) diet. Birds fed a non-supplemented diet provided information on the effects of aging on endogenous antioxidants. One hundred adult SUS males were used. Birds were sacrificed after 0, 4, 8 and 12 weeks on the diets and were examined for plaque development and corresponding antioxidant component alterations in aorta and myocardium. With aging, superoxide dismutase (SOD) activity was increased in both tissues, whereas aortic glutathione peroxidase (GPx) activity and myocardial glutathione reductase (GRd) activity decreased. Myocardial ascorbate levels increased with aging, with a reciprocal decrease in myocardial tocopherol levels. Following 4 weeks of cholesterol supplementation, aortic GRd decreased, SOD activity increased, but activities of GPx and catalase were unchanged. This same qualitative pattern of antioxidant enzyme changes was also found in myocardium. Thus, although aortic antioxidant enzyme changes produced by cholesterol feeding and aging showed some similarities, the early phase of atherogenesis does not simply reflect accelerated aging. In the late stages of atherogenesis, SOD activity returned to baseline, but other antioxidant enzymes remained unaltered from levels characterizing the early phase of lesion development. There was no detectable functional coupling between changes in GPx and GRd, nor between SOD (which produces hydrogen peroxide) and GPx or catalase (which utilize hydrogen peroxide as substrate). Previously reported alterations in erythrocyte antioxidant enzyme components during atherogenesis in quail were not predictive of changes in the corresponding enzymes in the aorta and myocardium.