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PubMed1986

Estimation of response to selection and utilization of control populations for additional information and accuracy.

Problems associated with testing and estimation of response to selection are examined. An alternative procedure with increased power for testing hypotheses is given. The increased power results from a more precise method of estimating the variance about response. The new method is based on a Satterthwaite approximation which combines variance components estimated more precisely by other sources of variation in the analysis of variance. The expected variance about response and expected mean squares for the analysis of variance, used in the Satterthwaite procedure, are given. When intergeneration environmental trends cannot be ruled out, a control population must be used to estimate response to selection. However, if the experimental and control populations do not respond in the same direction and with the same magnitude to common environmental effects, then the usual method of estimating response by deviating the experimental values from the control will result in biased estimates. An alternative procedure, using the control as a covariate to adjust for environmental trends, gives relatively unbiased estimates of response in this situation. Some bias results from measurement error associated with the control. However, this bias is usually minimal.

Analysis of Variance↗
PubMed1996

Socio-economic characteristics of artificial insemination donor (AID) couples compared with matched population controls.

Socio-economic characteristics like education, occupation and religion may play a role when choosing or refraining from treatment by artificial insemination by donor (AID). From a cohort of 189 AID-patients, the socio-economic characteristics were established from the notes and a questionnaire that was sent to all patients to complete the available data. The response rate to the questionnaire was 83.6% (158 women). Data were compared with population controls that were matched for age and region. AID patients in this study had significantly lower educational and/or occupational levels than matched population controls and were significantly more religious.

Adult↗
PubMed2001

[Two loci HLA haplotypes in celiac children. Linkage imbalance and haplotype frequencies. Comparative study with a control population].

OBJECTIVE: Celiac disease is closely correlated with certain human lymphocyte antigen (HLA) alleles. The aim of this study was to compare linkage disequilibrium parameters and the frequencies of the two loci haplotypes: HLA A/B, A/C, A/DR, A/DQ; HLA B/C, B/DR, B/DQ; HLA C/DR, C/DQ and HLA DR/DQ in children with celiac disease and in a control population within the same geographical area. METHODS: Thirty-eight children with celiac disease, aged 5months to 18years at diagnosis, were HLA typed by microlymphocytotoxicity assay using T and Bcells separated by monoclonal antibody labeled immunomagnetic particles. The frequency of each haplotype of two loci (Hij) depends on the frequency of each allele (pi and pj) and on a correction factor delta, according to the formula: Hij5 Dij1(pi3pj). The existence of a correction factor delta, or linkage disequilibrium, was assessed by a chi square test using 2 X 2contingency tables for gametic association. RESULTS: Among children with celiac disease the most frequent and significant haplotypes were A1/B8, A9/B5, A19/B12, A28/B22, A28/Cw1, A9/DQ3, B8/Cw7, B18/Cw5, B22/Cw1, B5/DR5, B8/DR3, B12/DR7, B5/DQ3, DR3/DQ2, DR4/DQ8 (3) and DR5/DQ3, showing a positive linkage disequilibrium. Negative linkage disequilibrium was found between B18/Cw7, B12/DR3, Cw4/DR3 and DR3/DQ3. CONCLUSIONS: Our findings show that the frequency of A1/B8,A19/B12, B8/DR3,B12/DR7 and DR3/DQ2 haplotypes is higher in children with celiac disease than in the control population and suggest that these two loci haplotypes confer susceptibility to celiac disease.

Adolescent↗
PubMed2000

Genetic polymorphisms of the IL-1alpha and IL-1beta genes in African-American LJP patients and an African-American control population.

BACKGROUND: A functional polymorphism of the interleukin-1 beta (IL-1beta) gene has been proposed to be a risk factor for periodontitis. In adult forms of periodontitis, non-smokers of northern European heritage carrying the "2" allele of the IL-1alpha-889 and the IL-1beta +3953 RFLPs in either the heterozygous or the homozygous state at both loci were observed to have a greater risk for developing severe periodontitis. Studies of early-onset periodontitis (EOP) found that allele "1" of both IL-1alpha-889 and IL-1beta +3953 was transmitted more frequently with the EOP phenotype. The purpose of the present study was to determine the prevalence of the IL-1alpha and IL-1beta genotype polymorphisms in an African-American (AA) control population and in 37 African-Americans with localized juvenile periodontitis (LJP). METHODS: The IL-1alpha +4845 and IL-1beta +3953 loci were genotyped by PCR amplification, followed by restriction enzyme digestion and gel electrophoresis. The IL-1alpha +4845 locus, in linkage disequilibrium (>99%) with IL-1alpha-889, was genotyped because it is technically easier. Data were analyzed using r x c contingency tables. RESULTS: The IL-1beta +3953 allele "1" was carried by >99% of the AA control population and by 100% of the AA LJP group, with most individuals being homozygous 1,1. The prevalence of the composite genotype with at least one allele "2" at each of the IL-1beta +3953 and IL-1alpha +4845 loci was 14% (AA control group) and 8% (AA LJP group). CONCLUSIONS: Given the high frequency of the IL-1beta allele "1" in the African-American population, it would appear that knowledge of this +3953 polymorphism would provide little diagnostic or predictive information for LJP.

Adult↗
PubMed2004

Insect population control using female specific pro-drug activation.

A system for population control of insects is proposed. It is based on transgenic insects expressing an enzyme which converts an inactive pro-drug into an active, toxic form. A model system is presented which relies on transposon-mediated integration of a bacterial cytosine deaminase (CD) gene into the genome of Drosophila melanogaster. We demonstrate female-specific sterility and transgene-dependent lethality when flies carrying the CD gene under a Drosophila female-specific promoter/enhancer are treated with 5-Fluorocytosine, a low-toxicity nucleoside analogue which is converted to toxic 5-Fluorouracil by the enzyme. The approach can be used with existing pro-insecticides and appropriate converting enzymes in combination with established mass rearing technology, for targeted, environmentally acceptable control of insects of economic and public health importance.

Animals↗
PubMed1999

Abortion rate during the second half of gestation of cows undergoing surgery in lateral recumbency as compared with cows of a control population.

In a retrospective study, we compared the abortion rates of 59 cows in the second half of gestation, admitted to the Clinic for Food Animals and Horses (1993-1996) with a strictly focal problem (head region, udder and teats, locomotor system) requiring surgery in lateral recumbency, to the abortion rate of a control cow population. Before surgery, a uterus relaxant was given in 42 cases, and 17 cows were untreated as to pregnancy. Cows included in the reproduction health program of the Department of Fertility and Reproduction were used as a control population. Data of 1,736 cows pregnant in the second half of gestation per year were available for the same time period (1993-1996). Abortion rate was 5.08% for the cows undergoing surgery in lateral recumbency as compared with 5.18% for the cows of the control population. There was no significant difference between the two populations (P > 0.05). Thus, the risk for abortion in the cows in question is not elevated as compared with the control population.

Abortion, Veterinary↗
PubMed1975

Population control in confined colonies of golden hamsters (Mesocricetus auratus Waterhouse).

The mechanisms by which confined colonies of Golden Hamsters regulate the density of their population were investigated. Six experimental populations were established with two males and two females each and allowed to grow freely for 3-8 months. At no time did any population exceed eight individuals. This appeared to be the result of a high rate of infant mortality due to failure of pregnant and parturient females to isolate themselves from the others. Two other populations were then established allowing many more nesting areas and more room for dispersal, but animals continued to crowd together and infant survival did not improve. These results contrast sharply with the large ultimate populations and only slowly developing disturbances seen in rats and mice. This difference in population control appears to be the direct result of a species difference in the tolerance of adults for strange newborns. In two further short-term experiments, the effects of the number and sex of adults in the founding population were systematically examined. The critical density at which no pups survived past the first day was six or more animals; females appeared to contribute more than males to infant mortality.

Animals↗
PubMed1977

Evaluation of control populations: body weight and rate of gain in Japanese quail.

1. Two control populations of quail of different origin were maintained by cyclical mating, one for 4 and the other for 6 generations. Means, heritabilities, genetic and phenotypic correlations of body weights at 1, 14 and 35 d and rates of gain from 1 to 14 d and from 14 to 35 d did not show any trend of change with generation. 2. The variability between generations was greater in the characters having intermediate and lower values of heritability, genetic and phenotypic correlations than in those with higher values.

Animals↗
PubMed1975

Attitudes toward population control in Santiago, Chile.

This article explores Chilean attitudes toward the national population's size and rate of growth, as indicated by a special survey conducted for this purpose. The survey sample consisted of 1,410 men 20 to 54 years of age in urban Santiago, who were separated into six categories on the basis of their education and socioeconomic status. The subjects were interviewed by 36 students from the University of Chile who utilized a prepared questionnaire including both open-ended and multiple-choice questions. The results clearly indicate that men in the lower socioeconomic categories tended to know less about the population's size and growth than their better-off counterparts. Nevertheless, they more often felt that Chile had "too many" inhabitants, that recent population growth had been rapid, and that this rate of growth should be reduced.

Adult↗
PubMed2000

The importance of control populations for the identification and management of genetic diversity.

A fundamental criterion for recognizing species or populations as potentially endangered is the presence/absence of genetic diversity. However, the lack of control populations in many studies of natural systems deprives one from unambiguous criteria for evaluating the genetic effects of small population size and its potential effects on fitness. In this study, I present an example of how the lack of adequate controls may lead to erroneous conclusions for understanding the role that population size may play in the preservation of genetic diversity and fitness of natural populations. The genetic analysis of a population of greater prairie chickens from Illinois, USA, between two time periods (1974-1987 and 1988-1993) in which the studied population experienced a substantial reduction in size and fitness showed no apparent associations between population size and genetic diversity. However, genetic analysis of museum specimens from early this century indicated that Illinois prairie chickens had originally higher levels of genetic diversity, which suggest the Illinois population was already bottlenecked by the 1970s. This study emphasizes the importance of using historical controls to evaluate the temporal dynamics of genetic variability in natural populations. The large number of museum collections worldwide may provide a valuable source of genetic information from past populations, particularly in species currently endangered as a result of human activities.

Alleles↗
PubMed1972

Population control.

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Developing Countries↗