H. L. Marks

Total Cholesterol, Total Triglycerides, and Cholesterol Distribution Among Lipoproteins as Predictors of Atherosclerosis in Selected Lines of Japanese Quail

The proportions of plasma high and low density lipoprotein cholesterol have been linked to inherited tendency for atherosclerosis in humans. Studies were conducted with Japanese quail males from lines genetically selected for high and low TC and a randombred (unselected) control line that were fed 0.0 or 0.5% cholesterol for 12 weeks. Atherosclerotic plaques were more severe in the high than in the low line quail and in those fed cholesterol compared to non-cholesterol-fed quail. Serum TG, TC, VLDLC, LDLC, and HDLC were also higher in the high than in the low line quail and in cholesterol-fed vs. non-cholesterol-fed quail. Significant interactions indicated that TC and LDLC concentrations were more affected by dietary cholesterol in the high line than in the low line. The low line quail maintained higher HDLC and lower LDLC than the high line. Regression and correlation analyses revealed that although VLDLC, LDLC, and TC were significant predictors of atherosclerosis in the high line birds, the TC/HDLC ratio was a better predictor in the low line. The Japanese quail lines used herein represent useful experimental models for studies of genetic differences in atherosclerosis in humans.

Anatomical Response to Selection for Four-Week Body Mass in Japanese Quail

-We analyzed changes in masses, proportions, and water contents of components of Japanese Quail (Coturnix japonica) following long-term selection for 4-week body mass. Chicks from selected and control lines were sacrificed at 0, 1, 2, 4, 6, and 9 weeks of age and dissected into 12 components, including plumage, major muscle masses, visceral organs, and brain. Selection for 40 generations had led to more than a doubling in mature mass and a 26-28% decrease in the time required to achieve that size. The difference in growth rates was expressed only before the age of 2 weeks post-hatching, hence before chicks had achieved 50% of mature mass. Proportions of several organs and components during the growth period were not markedly affected, but the mass of the pectoral muscles of the selected chicks increased, and the mass of the brain and the wing area decreased, relative to body size. The absolute growth of the brain did not differ between lines. There were no differences between lines in the relative water contents of tissues of chicks of similar ages. These results suggest that growth rate can be increased without decreases in the apparent levels of functional maturity of tissues or changes in body proportions that lead to a decrease in the growth increment of a constraining tissue. Received 3 April 1984, accepted 4

An Analysis of Satellite Cell Content in the Semimembranosus Muscle of Japanese Quail (Coturnix coturnix japonica) Selected for Rapid Growth

Transverse sections of the semimembranosus muscle of a control (C) line of Japanese quail and of a line (P) selected for high body weight at 4 weeks of age were observed for nuclear content. The two lines were sampled at 4 days posthatching and at 4 weeks of age. The relative number of satellite cells decreased from 4 days to 4 weeks of age. The total number of satellite cells, however, appeared to increase as muscle length increased; this relation was not influenced by line effects. It was concluded that the greater number of nuclei in the longer fibers of P-line quail was principally the consequence of a greater mitotic rate in the satellite cells of this line compared to the C-line quail.

Insensitivity of brain growth to selection of four-week body mass in Japanese quail

Within large taxonomic groups (i.e., orders and classes), the logarithm of brain mass is related to the logarithm of body mass with a slope typically on the order of .50 to .68 (see Brody, 1945; Count, 1947; Gould, 1975; Eisenberg, 1981; Martin, 1981; Martin and Harvey, 1984). Within smaller taxonomic groups (i.e., genera and below), however, this allometric relationship commonly has a reduced slope, which can be as low as .2.4 in extreme cases (see Huxley, 1932; Weidenreich, 1941; Martin and Harvey, 1984). To explain the discrepancy between these slopes, Lande (1979) and others have proposed that selection during the differentiation of closely related taxa acts primarily on body size, and the response of brain size is due mostly to its genetic correlation with body size rather than its direct selection. If this were true, the steeper brain-body slope observed within larger taxa would then necessarily result from subsequent direct selection upon brain mass, presumably related in some way to consequences of a change in body mass. Selection on brain mass in mice has revealed a realized heritability of .64 (Roderick et al., 1976). Lande (1979) used this figure and other data to estimate the genetic correlation between brain and body mass in nonprimate mammals to be about .7. Riska and Atchley (unpubl.) have directly estimated the genetic correlation between mature brain mass and body mass at various ages in rats and mice to be between .4 and .7. In this paper, we examine the response of the brain and other body components to selection for 4-week body mass in Japanese Quail and compare the response to the brain-body mass relationship among galliform birds. If the brain-body mass relationship within species reflects a strong genetic correlation, then we would expect to see a response in brain mass even to short-term selection on body mass. Selection for 4-week body mass in Japanese Quail (Coturnix coturnixjaponica) has resulted in a more than 2-fold increase in mature (16 week) body mass (Marks and Lepore, 1968; Marks, 1978a). The rate at which mature mass is achieved also increases following selection. Marks (1978b) fitted growth data (mass versus age) for selected and control strains with logistic equations having the form W(t) = A[1 + b exp(-Kt)]-1, where W(t) is the mass of the chick at age t, A is the asymptote or mass plateau of the growth curve, and K is the rate (time1) at which the asymptote is achieved. Fitted values of K were 40% greater in selected strains than in the control strain (Marks, 1 978b). Other traits also responded to selection. Egg mass increased approximately 20% (Marks, 1979) and the mass of the yolk of the egg by about 8% (Ricklefs and Marks, 1983). The increased mass of selected chicks is accompanied by an increase in the length of the bones of the appendages, indicating a general increase in all parts of the body. Although skeletal muscles of selected chicks are larger than those of controls, amounts of protein, RNA, and DNA per gram of tissue, as well as muscle fiber diameters and activities of certain enzymes do not differ (Fowler et al., 1980). This suggests enlargement of mus-

A comparative study of embryonic development of Japanese quailselected for different patterns of postnatal growth

Patterns of early embryonic development have traditionally been viewed as invariant within vertebrate taxa. It has been argued that the specific differences which are found arise during the later stages of development. These differences may be a result of allometry, heterochrony or changes in relative growth rates. To test whether early embryonic development is indeed invariant, or whether selection of adult characteristics can alter embryonic growth, we compared embryonic development in birds selected for different patterns of postnatal growth. Using quail lines selected for high and low body mass, we compared somite formation, and muscle and feather development. We obtained data that showed changes in the rate of myotome formation in the brachial somites which contribute to muscle formation in the limbs and thorax. We think these observations are connected with intraspecific changes in adult morphology, ie., breast muscle size. Our findings suggest that selection for late ontogenetic/adult stages affects early embryonic development.

A fast HPLC analysis of cholesterol and cholesteryl esters in Avian plasma

Abstract A rapid HPLC method for the quantitation of free cholesterol and cholesteryl esters in avian plasma is described. After extraction with isopropanol, free cholesterol and cholesteryl esters were eluted with acetonitrile-isopropanol (50:50, v/v) on a short, 3μ, reversed-phase column within 24 min and detected at 210 nm. The assay was used to evaluate differences in the free cholesterol and cholesteryl esters contents of blood plasma from Japanese quail genetically selected for high and low plasma cholesterol levels. Selection has altered cholesteryl ester distribution in quail, and may provide clues regarding genetic control of cholesterol metabolism.

Dietary Cholesterol Metabolism in Japanese Quail Lines Selected for Plasma Cholesterol Levels

Abstract Dietary cholesterol metabolism was studied, using a single dose of emulsion, per os (test meal), in lines of Japanese quail that were divergently selected for high (HL) and low (LL) plasma total cholesterol. The meal contained [3H] cholesterol, [14C] β-sitosterol, unlabeled cholesterol, triolein, and bile salt. Recovery of the non-absorbable β-sitosterol in the excreta permitted determination of the percentage of cholesterol absorbed. The amounts of [3H] in the plasma, egg yolks, and the excreta neutral and acid sterols were determined. A line-x-time interaction for [3H] in plasma indicated that the level of plasma cholesterol derived from the test meal declined more rapidly in the LL than in the HL. The higher [3H] detected in the excreta acidic sterols of the LL 12 hr after the test meal indicated that bile acid excretion of cholesterol was greater in the LL than in the HL. There were no differences in cholesterol absorption between lines or sexes. Cumulative [3H] radioactivity in the eggs over 18 days following the test meal was higher in the HL yolks; however, this line effect was due to the grater number of eggs produced by the HL. Thus, one of the mechanisms by which the LL maintains low plasma cholesterol levels is by an enhanced excretion of bile acid compared with the HL. The data also suggest that the more severe atherogenic effect of dietary cholesterol observed in the HL could be, in part, due to the longer residence time of cholesterol in circulation.

Effects of phenobarbital and β-naphthoflavone on the in vivo toxicity and in vitro metabolism of aflatoxin in an aflatoxin-resistant and control line of chickens.

The in vivo toxicity of aflatoxin and the in vitro microsomal metabolism of aflatoxin B1 (AFB1) were investigated in a population of chickens previously selected for resistance to aflatoxin (AR line) and a corresponding control population (NS line) after in vivo pretreatment with saline, sodium phenobarbital (PB), or beta-naphthoflavone (BNF) solutions. PB pretreatment increased survival and BNF pretreatment increased mortality in both the NS and AR lines when a single oral dose of aflatoxin was administered. The rate of in vitro metabolism of AFB1 was greater with microsomes from saline pretreated AR chicks than with microsomes from similarly treated NS chicks. In vivo pretreatment with PB increased AFB1 metabolism by NS and AR microsomes. After BNF pretreatment of vivo, AR microsomes metabolized more AFB1 than NS microsomes, and there was a dramatic decrease in AFB1 metabolism in NS microsomes. AFB1-dihydrodiol was the major metabolite produced by both lines, with aflatoxin M1 and aflatoxin Q1 recovered in small quantities from BNF-pretreated AR microsomal incubations only. These data indicate that increased in vivo resistance of the AR line to acute aflatoxicosis may be related to increased hepatic AFB1 metabolism and that genetic selection has resulted in altered in vitro quantitative and qualitative metabolism of AFB1 in the AR line.

History of the Athens Canadian Random Bred and the Athens Random Bred control populations

The University of Georgia maintains two meat-type chicken control strains: the Athens Random Bred (ARB) and the Athens Canadian Random Bred (ACRB). The Athens Random Bred was developed from colored plumage commercial meat chicken strains in 1956. The ACRB is a replicate population of the Ottawa Meat Control strain which was developed in 1955 from white plumage commercial meat-type chickens. These genetic lines have been extremely valuable research resources and have been used extensively to provide comparative context to modern meat-type strains. The ACRB may be the oldest pedigreed control commercial meat-type chicken still in existence today. This paper reviews the history of the breed backgrounds for both control populations and reviews research utilizing the ACRB.

Epitopes for chicken monoclonal antibodies in spleens of selected Japanese quail lines.

A line of Japanese quail selected for high plasma cholesterol is highly susceptible to diet-induced atherosclerosis. Lymphocyte epitopes recognized by mouse anti-chicken monoclonal antibodies (c-mAb), TCR-1, TCR-2, TCR-3. CD-3, CD-4, CD-8, and BU-1a/b were reacted with spleens from quail selected for high (HL) and low (LL) plasma total cholesterol and their nonselected controls (CL). Cross reactivity to c-mAb and effect of line and gender were immunohistochemically evaluated. Chicken spleens were positive controls. Quail were immunologically stimulated with either sheep red blood cells (SRBC) or Brucella abortus 2 weeks before spleens were removed. Quail spleen epitopes of all lines recognized TCR-3 and CD-8 c-mAb, but no other c-mAb. Number of reacting cells and staining intensity to the TCR-3 c-mAb were greater in the HL than in the LL regardless of the stimulating Ag or dose used. For the CD-8 c-mAb, there were no differences among lines in birds receiving SRBC. In B. abortus-immunized birds, sex x line interactions indicated that males of the HL and CL had lower responses than females but LL males were not different than females. TCR-3 and CD8 c-mAb may be useful in studying immunological mechanisms for atherosclerosis in Japanese quail.