Biomedical subjects

H L Marks

Publications and source records attributed to H L Marks.

At least 37 records · Page 2Linked to original sources

PubMed1994

Long-term comparisons of eight-week body weight for a randombred line of chickens reared at two locations.

For 36 generations, 8-wk body weight was measured in Athens-Canadian Randombred males and females reared at the Southern Regional Poultry Genetics Laboratory (SRPGL) and at Virginia Polytechnic Institute and State University. Regressions of this trait on generations ranged from -.7 g for females reared in Virginia to -2.6 g for males reared at the SRPGL. Chickens were consistently heavier at the SRPGL, where a broiler diet was fed, than at Virginia, where the diet was considerably lower in protein and energy. Highly significant (P < or = .01) location by generation interactions reflected fluctuations at one location that were independent of those at the other location. Correlations between body weight at the two locations increased when chicks were vaccinated for Marek's disease.

Animals↗

PubMed1994

Selection for eight-week body weight in two randombred chicken populations under altered water to feed ratios. 2. Feed intake, water intake, and abdominal fat levels.

Four experiments were conducted to investigate feed and water intake, feed efficiency, and abdominal fat levels of six lines of chickens developed from two randombred control populations following selection for high 8-wk BW under high (1.6%), low (.2%), and normal (.4%) dietary salt selection environments. The Athens-Canadian Randombreds (AC) and Athens Randombreds (ARB) served as base populations for development of the six lines. Progeny from these lines were evaluated in the first, fifth, sixth, and seventh generations in Experiments 1, 2, 3, and 4, respectively. In Experiment 1, abdominal fat levels were shown to be inversely related to dietary salt level. The lowest abdominal fat level was observed in birds fed the 1.6% salt diet and the highest abdominal fat level in birds fed the .2% salt diet. Birds receiving the normal (.4%) salt diet had intermediate abdominal fat levels. In Experiments 2, 3, and 4, selected lines were exposed to different dietary salt levels to measure both line and dietary salt response patterns. Significant (P < .05) differences were observed between genotypes (AC vs ARB) and between dietary salt treatments for BW, feed and water intake, and water to feed ratio. However, there was no evidence of genetic change between lines in abdominal fat level as a result of selection under different salt environments.

Adipose Tissue↗

PubMed1993

Heritabilities of growth curve parameters and age-specific expression of genetic variation under two different feeding regimes in Japanese quail (Coturnix coturnix japonica).

This study investigated genetic variation in growth and final size in relationship to differences in heritabilities under good and poor feeding conditions. Heritabilities of growth and final size were estimated for several traits under ad libitum and restricted feeding conditions. A 30% feed restriction from hatching to 44 days of age in Japanese quail chicks decreased body weight and tarsus length at 44 days of age and the length of the third primary convert feather at 24 days of age relative to controls fed ad libitum. Wing length at 44 days of age was not significantly different for ad libitum fed and restricted quail. Genetic variances for body weight and tarsus length were very large throughout growth which resulted in heritability estimates close to one for these traits. The genetic correlations among feeding treatments were low, indicating that different genes were affecting growth under the two treatments. Growth was described by the components: asymptote, growth period, and shape of the growth curve following the modified Richards growth curve model (Brisbin et al. 1986). Tarsus length, which had high heritability of the parameter 'growth period' of the model, tended to display a higher heritability under the restriction than under ad libitum feeding. Body weight and feather length, which had either no heritable or low heritable 'growth periods' estimates, tended to be more heritable under ad libitum feeding. The shape parameter of the growth curve was not heritable for any trait, except tarsus length under restricted feeding.

Age Factors↗

PubMed1993

Overexpression of a truncated growth hormone receptor in the sex-linked dwarf chicken: evidence for a splice mutation.

Sex-linked dwarfism in chickens is a form of GH resistance that resembles the Laron syndrome in humans. The dwarfism found in chickens is due to a mutant gene (dw) carried on the sex chromosome. The homozygous dwarf (dwdw) chicken is characterized by reductions in stature and plasma insulin-like growth factor-I (IGF-I) levels. Despite the absence of hepatic GH-binding activity, Southern blot analysis shows that there is no gross structural change in the gene for the GH receptor (GHR) in this strain of dwdw chicken. GH-dependent IGF-I production can be restored in cultured dwdw hepatocytes after transfection and transient expression of a chicken GHR (cGHR) cDNA, indicating that other factors that participate in GH-mediated IGF-I synthesis are intact. Northern blot analysis of liver, muscle, fat, and pituitary RNA from normal (DwDw) chickens shows a major transcript of 4.3 kilobases (kb) and three minor transcripts (0.8, 1.7, and 3.2 kb), which correspond to the cGHR. In contrast, the 0.8-kb transcript is the major cGHR transcript expressed in these tissues from dwdw chickens. Northern blot analysis with domain-specific probes shows that the 0.8-kb transcript in DwDw and dwdw liver contains only a small portion of the extracellular domain of the cGHR. A cDNA clone encoding this transcript has been isolated from a liver library prepared from a normal chicken.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1993

Delayed somite formation in a quail line exhibiting myofiber hyperplasia is accompanied by delayed expression of myogenic regulatory factors and myosin heavy chain.

A myofiber hyperplastic quail line P has been developed through selection for heavy body weight. Since the number of muscle fibers is determined early in development and skeletal muscle originates from somites, we compared somite formation and muscle-specific gene expression in P- and control C-line quail embryos. At 47 hours of incubation, C embryos had 18 somite pairs and P embryos had 14.3. By 72 and 120 hours, both lines appeared to be at the same stage of somite development. To determine whether the delay in the formation of the brachial somites was accompanied by alterations in muscle-specific gene expression, we conducted whole-mount in situ hybridization and immunofluorescence studies. At 47 hours of incubation, C embryos were expressing qmf1 in the first 12 somites, while in P embryos only the first 7 somites showed qmf1 activation. Delays in expression were also observed for qmf3 at 43 hours and for all three myogenic factors (qmf1, qmf2 and qmf3) at 60 hours. At 65 hours, C embryos expressed myosin heavy chain in the first 15 somite pairs and P embryos in the first 7. At 72 hours, the transient delay in somite formation had disappeared and there was no lag in myosin heavy chain expression between the lines. The phase delay in brachial somite formation, myogenic factors and myosin heavy chain expression may be associated with the observed myofiber hyperplasia in P-line quail by allowing an increase in the muscle stem cell population.

Animals↗

PubMed1993

Carcass composition, feed intake, and feed efficiency following long-term selection for four-week body weight in Japanese quail.

A study was conducted to determine BW, feed intake, feed efficiency, and carcass composition changes following 51 generations of selection for high 4-wk BW in Japanese quail. Quail lines utilized were the P line selected for high 4-wk BW on a normal 28% CP diet and the unselected base population (C line) from which the P line originated. Body weight, feed intake, and feed efficiency data were collected daily from 1 to 28 days, whereas percentage carcass water, ash, protein, and total lipid data were obtained at 0, 4, 7, 10, 14, 21, 28, 42, and 56 days of age. Body weights of P line quail were significantly (P < .05) larger than BW of C line quail at all ages with the greatest deviation occurring at the age of selection. Feed intake was significantly greater in the P line and paralleled BW increases. When feed intake was adjusted for differences in BW, P line quail consumed less feed per gram of BW than C line quail and adjusted feed intake declined with age after Week 1. The P line quail had superior feed efficiency compared with C line quail from 1 to 13 days of age with the greatest deviation immediately posthatch. Carcass composition determinations revealed significant (P < .05) age and line effects. Both percentage ash and protein increased from hatch to 14 days and thereafter remained constant. However, percentage water and total lipid demonstrated contrasting responses to increasing age; percentage water declined whereas percentage total lipid increased. The P line quail had less carcass water and protein, but had more lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1993

The influence of dietary protein level on body weight of Japanese quail lines selected under high- and low-protein diets.

Two experiments were conducted to determine the protein requirement of quail lines (P and T) following selection for increased 4-wk BW under normal-protein (28% CP) and low-protein (20% CP) diets, respectively. Quail progeny from Generation 39 breeders were fed diets containing 18, 21, 24, and 27% CP from 0 to 5 wk of age in Experiment 1, whereas in Experiment 2, quail progeny from Generation 79 breeders were fed diets containing 18, 21, 24, 27, and 30% CP from 0 to 4 wk of age. Quail from the unselected base population (C line) were also included in both experiments. Significant line, diet, and line by diet interactions were present in both experiments. At 2 wk of age, T line quail were significantly (P < .05) larger than P line quail across diets, whereas by 4 wk, BW of P line quail were significantly larger than those of T line quail. Across dietary protein levels, quail receiving diets containing 24% CP or higher were significantly larger than those receiving the 18 and 21% CP diets. Quail in both the P and C lines had larger BW with increasing protein levels and an apparent protein requirement between 24 and 27% CP. However, quail in the T line showed no BW response to increased protein levels, indicating that long-term selection for increased BW on a 20% CP diet had altered the protein requirement in this line.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 7. Heterosis and combining ability among diallel crosses following twenty-seven generations of selection.

Growth patterns of quail lines divergently selected for 4-wk BW under split and complete nutrition environments were investigated utilizing a diallel mating scheme. The design, involving 16 mating combinations, allowed investigation of heterotic effects, reciprocal cross effects, and combining ability. Progeny from Generation 27 breeders were evaluated in two hatches under both selection diets. Heterosis for hatch weight was essentially zero; however, percentage heterosis from High x High crosses and Low x Low crosses ranged from 5 to 18% after 1 wk of age. Quail progeny from Low x High crosses were consistently larger than quail from reciprocal High x Low crosses under both selection diets. Reciprocal differences were greatest immediately posthatch and declined with age. However, in crosses involving males from High and Low split diet lines mated to females from High and Low complete diet lines, large reciprocal differences in BW remained at 8 wk. Mean heterosis values for BW across ages from crossing High and Low lines both within and across selection environments were negative in six of eight comparisons. Mean values ranged from +3 to -11% and indicated that greater selection responses may have been made in divergent selection for low 4-wk BW than for high BW. General combining ability of lines was greater when transmitted via females as opposed to males, and was similar under the two diets (split and complete). There was evidence that high-BW lines exhibited greater general combining ability under both dietary environments than did low-BW lines.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Plasma and yolk cholesterol levels in Japanese quail divergently selected for plasma cholesterol response to adrenocorticotropin.

Studies were conducted to determine the effect of divergent selection for plasma cholesterol response to adrenocorticotropin (ACTH) on the levels and relationships between plasma and yolk cholesterol in Japanese quail. Cholesterol data were obtained in Generation 25, following seven generations of relaxed selection, from birds maintained under a normal environment with no exposure to exogenous ACTH. Levels of plasma and yolk cholesterol were determined at 22 and 28 wk. Plasma cholesterol levels of quail in the low cholesterol line were significantly (P less than .01) lower than levels in the high line at both ages (224 versus 383 and 209 versus 326 mg/100 mL, respectively). In contrast, yolk cholesterol levels were significantly (P less than .01) higher in the low line than in the high line (24.1 versus 21.5 and 21.1 versus 16.9 mg cholesterol/g yolk at 22 and 28 wk, respectively). A significant line by sex interaction was present at both ages for plasma cholesterol with females having higher cholesterol values than males in the low line and males having higher values than females in the high line. A negative relationship was observed between changes in plasma and yolk cholesterol in the selected lines. Greater deposition of cholesterol in the yolk of the line with lower plasma cholesterol indicates that excretion rate may play a role in explaining genetic differences in plasma cholesterol.

Adrenocorticotropic Hormone↗

PubMed1991

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 4. Genetic and correlated responses from generations 12 to 20.

Divergent selection during Generations 12 to 20 for high (H) and low (L) 4-wk BW under split-(SD) and complete-(CD) diet environments resulted in continued progress in both upward and downward directions. Following 20 generations of selection, there were 4.8- and 3.6-fold differences between BW of H and L lines in the SD and CD environments, respectively. Regression coefficients of mean 4-wk BW on generation of 1.88 and 1.58 g in the H lines and -1.50 and -1.37 g in the L lines indicated symmetrical selection responses. Realized heritabilities for 4-wk BW ranged from .2 to .4; selection differentials were significantly (P less than .01) larger in the H lines than in the L lines. Directional changes in 2-wk and adult BW and in egg weight across generations were similar to that of the selection trait (4-wk BW). Selection resulted in decreased hatchability and egg production and an increase in the age of sexual maturity. However, these changes were smaller than corresponding changes observed in earlier generations (0 to 11). Egg size of lines selected in the SD environment continued to be larger than egg size of corresponding lines in the CD environment. Considerable genetic variation for BW remains under both SD and CD environments following 20 generations of divergent selection. Smaller gains resulting from lower heritabilities agree with theoretical expectations of decreasing responses accompanying continuous selection.

Animals↗

PubMed1991

Effects of selection on plasma thyroxine concentrations in Japanese quail under thiouracil and protein stress.

Three experiments were conducted to measure changes in plasma thyroxine (T4) concentrations occurring in male and female Japanese quail in response to treatment with dietary thiouracil (TU) and different CP levels prior to sexual maturity and to determine the influence of selection for growth under TU and protein stress on this response. Selected and unselected lines of quail were fed diets containing .2% TU or two levels of CP (20 or 28%) or both from 0 to 4 wk of age. Body weight and plasma T4 were measured at 5, 7, and 9 wk of age in Experiments 1 and 2. In Experiment 3, body weight was measured at 2, 4, 5, 7, and 9 wk and T4 at 4, 7, and 9 wk. Thiouracil inhibited growth to a greater degree than did decreased dietary CP. However, offspring from selected quail were more resistant to dietary TU when selection diets contained TU. When fed as part of a selection regimen rather than to unselected birds, low CP, TU diets inhibited body weight increase to a greater degree and longer after birds were returned to control diets. Thyroxine concentrations between 4 and 9 wk were affected by TU but not by CP level. Thiouracil significantly reduced T4 during treatment; however, T4 was elevated by 3 wk after cessation of TU treatment. Increases in T4 were greater and more immediate in selected than in unselected birds. These findings reveal the ability of quail to compensate for thyroid suppression after TU is removed from the diet and the influence of selection on this compensatory response.

Animals↗

PubMed1991

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 5. Feed intake and efficiency patterns following nineteen generations of selection.

High (H) and low (L) quail lines divergently selected for 4-wk BW under complete-diet (CD) and split-diet (SD) environments were evaluated to examine changes in feed intake and feed efficiency before and after the age at selection. Progeny from the four quail lines (H-SD, L-SD, H-CD, L-CD) were fed the CD in Generation 17 and the SD in Generation 19. The BW of H-line quail were highest under their respective selection environments, and the BW of quail in the L lines were highest under reciprocal environments. However, the BW of the two H lines were similar as were those of the two L lines. Relative growth rates of H-line quail were superior to those of L-line quail for the first 2 wk posthatch but L-line rates were superior after Week 4. However, the BW of H-line birds were always higher than for the L-line birds. Adjusted feed intake (grams of feed per 100 g of BW) values for the H lines were similar but lower than values for the L lines. Differences in adjusted feed intake between the H and L lines from 1 to 10 wk remained constant, although adjusted feed intake declined with age in all lines. Feed efficiencies (grams of gain divided by grams of feed) were superior in the H lines for Weeks 1 through 3 and superior in the L lines for Weeks 5 through 9. The same relative shifts between lines were observed in relative growth rates. Therefore, feed efficiency, in addition to feed intake, appears to play an important role in the divergence of BW in the H- and L-quail lines.

Abdomen↗

PubMed1991

Effects of selection for growth and selection diet on eggshell quality and embryonic development in Japanese quail.

Decreased hatchability in Japanese quail following selection for growth and relative improvements in hatchability following selection during goitrogen treatment were investigated. An unselected quail line (Line C) and lines selected for high 4-wk body weight while being fed diets containing either 20% CP and .2% thiouracil (TU) (Line T), or 28% CP and no TU (Lines P and H-CD) were used. Egg weight loss between 0 and 4, and 0 and 14 days of incubation, hatchability, and developmental stage of embryonic mortalities were determined in Experiment 1. Length of the incubation period, and percentages of body water and dry body weight were determined for 10- and 14-day embryos and 18-day-old chicks in Experiment 2. Eggshell quality was determined in Experiment 3. Hatchability was lower in selected than in unselected quail due to increased early and late embryonic mortality. Egg weight loss during incubation was greater in Line P than in Line C eggs. Weight loss, measured across lines, was lower in eggs that hatched than in those in which embryos died early. Percentage body water was higher in Line C than in Lines P and T at 14 and 18 days of incubation; however, percentage body water in Line T was lower than Line P at 14 days. Percentage of dry body weight was greater in Lines P and T than in Line C at 14 and 18 days. Eggshell thickness was greater in Line H-CD when compared with Line C. Increases in eggshell permeability occurring during selection for growth were associated with increased embryonic mortality and decreased hatchability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Body, abdominal fat, and testes weights, and line by sex interactions in Japanese quail divergently selected for plasma cholesterol response to adrenocorticotropin.

Line by sex interactions of BW, abdominal fat, testes weight, and plasma cholesterol were investigated in two Japanese quail lines. High (H-PCHOL) and low (L-PCHOL) quail lines had been developed by 18 generations of divergent selection for plasma cholesterol response to adrenocorticotropin (ACTH). Quail were from Generation 28 breeders maintained under a normal environment with no exposure to exogenous ACTH after Generation 18. Quail from growth-selected lines were also used to examine relationships between BW and plasma cholesterol. Body weights of H-PCHOL quail were significantly (P less than or equal to .05) heavier than BW of L-PCHOL quail at 2 and 4 wk of age. However, at 8, 16, and 28 wk BW were similar. Quail from long-term, growth-selected lines were observed to have plasma cholesterol levels similar to those of control lines. Therefore, early BW changes in H-PCHOL and L-PCHOL lines may not be related to plasma cholesterol changes. At 2 and 4 wk, male and female plasma cholesterol values were similar in the H-PCHOL and L-PCHOL lines, however, at 8 and 16 wk males had higher values than females in the H-PCHOL line, and females had higher values than males in the L-PCHOL line. Because interactions were present only after sexual maturity was reached, sex hormones may be involved in the expression of these interactions. Quail in the L-PCHOL line were observed to have significantly (P less than or equal to .05) more abdominal fat and significantly (P less than or equal to .05) smaller testes than quail in the H-PCHOL line.

Abdomen↗

PubMed1991

Changes in organ growth pattern associated with long-term selection for high growth rate in quail.

Data are presented on the pattern of organ growth in embryos from a line of Japanese quail selected for high growth rate and compared with those from a non-selected control line. The data reveal that the increased growth rate post hatching is accompanied by a more rapid early development of the digestive organs. It appears from these results that the "genes for" growth rate are the "genes for" early growth of the digestive organs.

Animals↗

PubMed1990

Effects of phenobarbital and beta-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.

Aflatoxins↗

PubMed1990

Plasma cholesterol responses to the adrenocorticotropic hormone in Japanese quail following eighteen generations of divergent selection.

Japanese quail (Coturnix coturnix japonica) lines were divergently selected for plasma cholesterol response to adrenocorticotropin (ACTH). Data for Generations 9 to 18 indicated a greater response in the low (L) line than in the high (H) line, which was contrary to selection responses for the first eight generations. During Generations 9 to 18, selection differentials were greater in the H line; however, heritability estimates were greater in the L line. These data suggest caution in the interpretation of early selection responses for plasma cholesterol. Selection for plasma cholesterol response following ACTH injection also resulted in divergence in plasma cholesterol levels in the H and L lines in the absence of ACTH. Body weights at 31 days were greater in the H line than in the L line, suggesting a possible relationship with the plasma cholesterol level.

Adrenocorticotropic Hormone↗

PubMed1990

Effects of dietary aflatoxin in aflatoxin-resistant and control lines of chickens.

The resistance to a single oral dose (12 mg of aflatoxin per kg of BW) and 4 wk of dietary aflatoxin (2.5 mg per kg of feed) were investigated in chicks selected for five generations for resistance to acute aflatoxicosis (AR) and unselected control (C) chicks. The AR chicks were more resistant to a single oral dose of aflatoxin and had significantly decreased sodium pentobarbital sleeping time compared to C chicks. Four-weeks exposure to dietary aflatoxin did not result in any significant change in BW or feed conversion ratios of chicks from either the C or AR line. However, more sensitive indicators of aflatoxicosis including plasma total protein, albumin, cholesterol concentrations, and gamma glutamyl transferase activity were significantly altered in C chicks but not in AR chicks fed aflatoxin. Percentages of liver lipid and liver hyperplasia score were also significantly altered as a result of dietary aflatoxin treatment in C but not AR chicks. These data indicate that selection-associated differences exist between the C and AR lines of chickens that convey resistance to not only a single oral dose of aflatoxin but also to a more chronic dietary exposure to aflatoxin.

Aflatoxins↗