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Biomedical subjects

J J Rutledge

Publications and source records attributed to J J Rutledge.

At least 55 records · Page 3Linked to original sources
PubMed1981

Growth hormone and prolactin synthesis in normal and homozygous Snell and Ames dwarf mice.

The severe growth retardation and sterility characteristic of Snell and Ames dwarfs, two nonallelic, recessive mouse mutants, have been attributed to a deficiency in pituitary production of GH and PRL. We have investigated the synthesis of these hormones in normal and homozygous dwarf mice of both strains at various stage of development to determine whether the mutations prevent initial development of the pituitary capacity to produce these hormones. Synthesis of radiolabeled GH and PRL was assayed by two-dimensional electrophoresis and immunoprecipitation using goat antisera to mouse GH and PRL. Litters in which all pups were mutant were produced by mating adult dwarfs made fertile by implanting a normal pituitary under the kidney capsule. We found that GH and PRL synthesis was undetectable in Snell or Ames dwarfs at all stages of development examined, including the neonatal period when dwarf pups are indistinguishable from normal littermates. Furthermore, we detected no immunoprecipitable peptides which might represent mutant hormones in these animals. Assays of GH synthetic rates in heterozygous animals indicated that there may be a slight negative effect of the mutant gene on GH synthesis in Snell animals. It was concluded that in the homozygous condition, both types of dwarf alleles result in failure of the pituitary to initiate GH and PRL synthesis.

Alleles↗
PubMed1981

Selection for feed conversion on efficiency and growth in mice.

Selection for feed conversion substantially influenced growth and gross feed efficiency of mice. Realized heritabilities and genic correlation for increased gain on fixed feed intake (FF) and decreased feed intake on a constant gain (FG) were estimated to be .56, .73 and -.93, respectively. The genic correlations between FF and 56-day weight and between FG and 56-day weight were estimated to be .67 and -.95, respectively. The relative efficiency in changing FF or FG by selecting directly for 56-day weight was found to be .7 in either case. When efficiency was defined as the incorporation of biomass independent of maintenance, no difference was found between selection treatments. Differences in mature weight and feed intake approached significance with selected lines having higher means than controls. The absence of a correlated response in the ability to use energy for growth indicates that selection for feed to gain ratio changes maintenance requirements but not requirements for growth.

Animal Feed↗
PubMed1980

Fraternity size and swine reproduction. I. Effect on fecundity of gilts.

Data from three generations of a selection experiment with Yorkshire swine were analyzed. Fraternity size was defined as the number of sibs at 2 weeks of age. In one line, potential replacements were reared in fraternity sizes initially set at six, while in the other two lines fraternity size was not altered. Over the period of study, gilts reared in small fratermites (mean = 5.77) averaged 11.30 pigs born, whereas gilts reared in an unaltered fraternity size (mean = 10.06) averaged 10.19 pigs born. Both of these lines had experienced two generations of selection for increased litter size. A randomly selected control line in which fraternity size (mean = 7.80) was not altered averaged 10.77 pigs born. Gilts reared in small fraternities were heavier at 21 days, but there were no significant body weight differences between lines at breeding or farrowing.

Animals↗
PubMed1980

Fraternity size and swine reproduction. II. Genetical consequences.

A model for swine fecundity that includes the effect of fraternity size is given. Over a range of plausible values for the parameters of the model, the dam-daughter correlation for number born tended to be negative. Thus, selection of replacement gilts born and reared in large litters would not bring about desirable genetic changes in litter size.

Animals↗
PubMed1979

Impeded cerebellar development and reduced serum thyroxine levels associated with fetal alcohol intoxication.

Pregnant albino rats were placed on a complete liquid diet (Ensure) containing either 9% ethanol or an isocaloric amount of sucrose between the third and twentieth day of gestation. The pups born to these rats were sacrificed either day 11 or day 14 postnatum and morphometrical, histological and biochemical analyses were done on their cerebellums and cerebrums. Pups that were exposed to ethanol in utero had significantly smaller body weights, cerebrums and cerebellums than pair-fed controls. The cerebellar mass was reduced by 10% and the cerebral weight by 3% in the pups exposed to alcohol when body weights were normalized to that of pair-fed controls. Cerebellar aspartyl aminotransferase (EC 2.6.1.1) activity was reduced at day 11 and 14 in ethanol treated pups compared with controls. Serum T4 levels were also reduced in the ethanol treated group. Histological analyses revealed that the external granule cell (EGC) layer of ethanol treated pups was significantly thicker at 11 and 14 days postnatum than that of pair-fed control pups. Cerebellar ornithine decarboxylase (ODC, EC 4.1.1.17) activity was higher at day 11 in the ethanol treated pups than in controls. The reduced mass, AAT activity, T4 serum levels and the increased thickness of the ECG layer indicate a delayed or impeded maturation of cerebellum in ethanol treated pups. These data are considered from the viewpoint that ethanol, other drugs such as methadone and prenatal stress (malnutrition) may cause delayed cerebellar maturation by reducing serum T4 levels in the early postnatal period (day 5-14).

Alcohol Drinking↗
PubMed1979

Responses to selection for body weight in descendants of X-irradiated rats.

The effectiveness of selection for high and low body weight at six weeks of age was studied in descendants of X-irradiated (R) and nonirradiated (C) inbred rats. There were two replicates of each of the direction of selection-irradiation treatments. In C lines, there were no consistent responses to selection, probably due to a low level of genetic variability. In R rats, selection was effective only for decreased body weight. The results of this experiment do not suggest the use of irradiation combined with selection as a means of enhancing responses to selection in animals.

Age Factors↗
PubMed1979

Effect of age and parity on litter size in pigs.

Litter size increased (P less than 0.01) as the age of the dam at farrowing increased. However, previous reproductive experience (parity) had no direct effect on litter size of dams of the same age.

Animals↗
PubMed1977

Effects of ancestral X irradiation followed by random mating on body weight of rats.

Effects of nine generations of 450r per generation of ancestral spermatogonial X irradiation of inbred rats on body weight were examined. After six generations of random mating (avoiding inbreeding) following the termination of irradiation, descendants of irradiated males (R) were significantly lighter than their controls (C) at 3 and 6 weeks, but not at 10 weeks of age. However, differences in growth between R and C populations were small. Among-litter and within-litter variance estimates were generally larger in the R lines than in the C lines, suggesting that selection responses would be greater in R than in C lines. In conjunction with previous evidence--obtained during the irradiation phase of the experiment--this suggested that more rapid response to selection for 6-week body weight, in particular, might accrue in the R lines.

Animals↗
PubMed1977

Estimates of genetic parameters of body weight in descendants of X-irradiated rat spermatogonia.

Effects of nine generations of 450r per generation of ancestral spermatogonial X irradiation of inbred rats on genetic parameters of body weight at 3, 6, and 10 weeks of age and of weight gains between these periods were studied. Covariances among relatives were estimated by mixed model and regression techniques in randomly selected lines with (R) and without (C) radiation history. Analyses of the data were based on five linear genetic models combining additive direct, additive indirect (maternal), dominance and environmental effects. Parameters in these models were estimated by generalized least-squares. A model including direct and indirect genetic effects fit more closely to the data in both R and C lines. Overdominance of induced mutations did not seem to be present. Ancestral irradiation increased maternal additive genetic variances of body weights and gains but not direct genetic variances. Theoretically, due to a negative direct-maternal genetic correlation, within full-sib family selection would be ineffective in increasing body weight at six weeks in both R and C lines. However, progress from mass selection would be expected to be faster in the R lines.

Aging↗
PubMed1973

An experimental evaluation of genetic correlation.

Heritability and genetic correlations realized from both single-trait and antagonistic index selection were compared with paternal half-sib estimates. Primary attention was focused on the genetic correlation between six-week body weight and six-week tail length. Parameters realized from single-trait selection were in excellent agreement with paternal half-sib estimates. However, the realized genetic correlation between six-week body weight and six-week tail length obtained from index selection was significantly greater than the other estimates. Differential inbreeding levels and realized selection intensities were considered and rejected as being causative factors for these results. Linkage disequilibrium probably was not a factor either, as the base population had been randomly mated and randomly selected with a large effective population size for many generations. It was concluded that with antagonistic index selection, the pleiotropic effects of genes may be more powerful in retarding response in aggregate genotype than current theory would suggest. Replication of all selected and control lines allowed the use of between-line estimators of sampling variances of realized genetic parameters in the above comparisons. Generally, standard errors of realized genetic parameters were much smaller than corresponding paternal half-sib standard errors. Thus, selection was an efficient method of estimation.

Animals↗