Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Inbreeding”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1999

Microsatellite loci in wild-type and inbred Strongylocentrotus purpuratus.

Strongylocentrotus purpuratus, a major research model in developmental molecular biology, has been inbred through six generations of sibling matings. Though viability initially decreased, as described earlier, the inbred line now consists of healthy, fertile animals. These are intended to serve as a genomic resource in which the level of polymorphism is decreased with respect to wild S. purpuratus. To genotype the inbred animals eight simple sequence genomic repeats were isolated, in context, and PCR primers were generated against the flanking single-copy sequences. Distribution and polymorphism of these regions of the genome were studied in the genomes of 27 wild individuals and in a sample of the inbred animals at F2 and F3 generations. All eight regions were polymorphic, though to different extents, and their homozygosity was increased by inbreeding as expected. The eight markers suffice to identify unambiguously the cellular DNA of any wild or F3 S. purpuratus individual.

Animals↗
PubMed1993

Effective population size in organisms with complex life-histories.

A method for determining effective population size in organisms with arbitrarily complex life-histories, including clonal reproduction, is developed. A coalescent model that focuses on the time at which two alleles last shared a common ancestor leads to a method for determining an inbreeding effective population size. Comparisons with previously developed approximate methods for haploid age-structured models show close, but not exact, agreement. A diploid population with both clonal and sexual reproduction is considered; examples from published demographic studies are used to show the effects of within-individual versus between-individual coalescence times and different definitions of generation time in calculating effective population size. These examples show relatively small differences in effective population sizes calculated using within- and between-individual coalescence times; however, in one case, different definitions of generation time lead to a large change in ratios of effective population size to census size (Ne/N). The Ne/N calculated for clonally reproducing organisms in this paper seem to be substantially smaller than published values for organisms lacking clonal reproduction.

Age Factors↗
PubMed1995

Two-locus drift with sex chromosomes: the partitioning and conversion of variance in subdivided populations.

A set of two-locus descent measures are derived for loci on sex-linked and autosomal loci, with a population structure which includes finite population size, migration, and extinction and recolonization. Two-locus descent measures which involve sex chromosomes increase much faster with inbreeding than those for autosomes. For loose recombination, the two-locus descent measures are shown to be closely approximated by the product of the appropriate one-locus measures. The distribution and partitioning of variance within and among populations is derived, including additive-by-additive epistatic genetic variance. The variance among populations available to group selection is much higher in the homogametic sex with epistasis involving sex chromosomes or haplodiploids. The amount of additive genetic variance within populations due to sex chromosomes or haplodiploids can be significantly increased as a result of population bottlenecks and the conversion of epistatic genetic variance. The proportion of epistatic genetic variance which is converted to additive variance is greater in the homogametic sex than in the heterogametic sex, by as much as a factor of 2.

Animals↗
PubMed1994

Mutation load depending on variance in reproductive success and mating system.

Equalization of reproductive success of individuals, although it results in an increase of effective population size, leads also to an increase of the mutation load. The magnitude of this increase depends highly on the mode of fitness interactions between deleterious mutations, and is higher in the case of inbreeding. Recommended practices in conservation genetics must be evaluated in regards to these differing consequences of an increase of effective population size. To keep a balance between retaining genetic variability and minimizing the increase of the mutation load, equalization of reproductive success of a set of individuals rather than of every individual might be more advantageous.

Animals↗
PubMed1992

Promoter methylation and progressive transgene inactivation in Arabidopsis.

Agrobacterium-transformed Arabidopsis plants were generated and the stability of their T-DNA-encoded resistance to kanamycin was examined. Of seven families, each homozygous for a single insertion event, two showed progressive inactivation of resistance over four generations of inbreeding. Loss of resistance was associated with methylation of an Sst II site in the nos promoter of the kanamycin resistance gene. Treatment of plant roots from inactive lines with the demethylating agent 5-azacytidine restored the ability of such lines to form callus on kanamycin-containing media. These observations are consistent with the view that methylation is a factor in the progressive inactivation of transgenes in Arabidopsis.

DNA, Bacterial↗
PubMed1988

Mdg-1 mobile element polymorphism in selected Drosophila melanogaster populations.

The changes in mdg-1 mobile element polymorphism that followed artificial selection for either high or low egg-to-adult viability in a Drosophila melanogaster population were investigated. The two selected subpopulations were thus characterized for fecundity, wing length, and number and location of the mdg-1 mobile element by in situ hybridization of the biotinylated--DNA on salivary gland chromosomes. The selected populations that differed greatly in egg-to-adult viability showed the same mean fecundity and identical values for intra and inter components of variances, intraclass correlation coefficient, and fluctuating asymmetry estimated on the wing length measurement. This indicates a non-correlated effect between deleterious mutations affecting viability and other fitness components. However, the two selected populations differed in their pattern of mdg-1 location, although the mean number of insertions per genome was not different from that of the initial population; hence, the number of insertions of the mdg-1 mobile element was independent of the effective population size. These results suggest that the mdg-1 copy number was regulated, and that during the selection process, drift and inbreeding made up new insertion patterns of the mdg-1 element in the selected populations. The results are discussed in the light of some recent theoretical models of the population dynamics of transposable elements.

Animals↗
PubMed1981

Genetic control of T-lymphocyte mitogenesis in chickens.

The in vitro mitogenic response to PHA and Con A was determined in three inbred lines of chickens. Lymphocytes from one line consistently showed a greater stimulation by PHA than the other two lines. Analysis of F1 crosses and backcrosses indicated that this quantitative difference was controlled by more than one gene. More substantial differences in Con-A stimulation were also observed between the three lines, and the data indicated that separate genetic systems were controlling the variation in PHA and Con-A stimulation. Analysis of F1 crosses, backcrosses and assortative matings between backcrosses revealed that the variation in Con-A stimulation was controlled by at least two major genes, one of which may be linked to the major histocompatibility complex. Surprisingly, one line appeared to be segregating for Con-A stimulation in spite of an inbreeding coefficient greater than 0.98.

Animals↗
PubMed1991

The genetic properties of homosexual copulation behavior in Tribolium castaneum: diallel analysis.

The rate of homosexual copulation has been defined as the ratio between the number of homosexual mountings and the total number of mountings (homo and heterosexual) performed by a Tribolium castaneum male during a period of 30 min. In a laboratory population, the average rate when a number of males (m) and females (k x m) are tested together has been estimated in each of the six situations defined by m = 2 and 10 and k = 0.5, 1, and 2, k being the sex ratio among scored individuals. Good agreement was found between the observed rates of homosexual copulation and those expected assuming random contacts between pairs of individuals totally indiscriminate with respect to sex. The genetic properties of the trait have been investigated by means of a diallel analysis of six highly inbred lines derived from the same population and their F1 crosses. Significant general and specific combining ability effects were detected. When noninbred females were used for testing, the rate of homosexual copulation is expected to be higher for inbred than for noninbred males. This prediction, implying the existence of inbreeding depression for the trait, also was confirmed by the data.

Alleles↗
PubMed1993

Behavior genetic differences within and between defined human populations.

The small populations of the Caucasus offer a unique opportunity to consider concepts, such as heritability, which are often considered properties of a trait but which are really properties of a population. A comprehensive strategy is outlined for studying intra- and interpopulation genetic structure across a wide range of traits and environments. A three-way association is demonstrated between 12 of 16 psychophysiological traits, attitude, and the t allele for PTC sensitivity. Differences between populations and traits are evaluated in theoretical terms for morphological, physiological, and psychological measures. While decreases in performance with inbreeding are often predicted, in these small, isolated populations the effects are minimal.

Adolescent↗
PubMed1981

Maternal effects in mice: influence of parents' and offspring's genotypes.

Different backcrosses between the F1 and two inbred parental strains (C and B6) were compared for swimming speed in water escape task and for swimming ability in a water channel. Results showed maternal effects, mice from an F1 dam swimming faster than mice from an inbred dam. Albino mice appear to be more sensitive to these effects could also be related to the inbreeding level of the offspring, the reciprocal backcrosses showing differences, whereas the two reciprocal F1's did not. Maternal effects appear to be greater in the water escape task than in the water channel situation.

Animals↗
PubMed1979

Chromomeres and puffing in experimentally induced polytene chromosomes of Calliphora erythrocephala.

In the most advanced types of meroistic ovaries the synthesis of RNA for the growing oocyte in each follicle is taken over by nurse cells, i.e., sister cells of the definite egg cell. In calliphora, the highly polyploid nurse cells (NC) develop a polytene karyotype under conditions of strict brother-sister inbreeding and using a controlled selection technique. A comparison of the polytene NC-chromosomes with those from the pupal bristle forming cells reveals an unexpected discrepancy: while both chromosome complements exhibit a constant banding pattern it is not possible to homologize the two tissue specific patterns by identifying homologous band-sequences. Puffing in NC likewise turns out to be unusual in its extent as well as in that is remains constant during long periods of oogenesis. In a more detailed discussion an interpretation and evaluation of these findings will be attempted.

Animals↗
PubMed1988

Biological and pathological consequences of feline infectious peritonitis virus infection in the cheetah.

An epizootic of feline infectious peritonitis in a captive cheetah population during 1982-1983 served to focus attention on the susceptibility of the cheetah (Acinoyx jubatus) to infectious disease. Subsequent observations based upon seroepidemiological surveys and electron microscopy of fecal material verified that cheetahs were indeed capable of being infected by coronaviruses, which were antigenically related to coronaviruses affecting domestic cats, i.e. feline infectious peritonitis virus/feline enteric coronavirus. Coincident with the apparent increased susceptibility of the cheetah to infectious diseases, were observations that the cheetah was genetically unusual insofar as large amounts of enzyme-encoding loci were monomorphic, and that unrelated cheetahs were capable of accepting allogenic skin grafts. These data provided the basis for a hypothesis that the cheetah, through intensive inbreeding, had become more susceptible to viral infections as a result of genetic homogeneity.

Acinonyx↗
PubMed1992

The effect of genetic variability (degree of homozygosity) on serum levels of the anterior pituitary hormones prolactin, corticotropin, and growth hormone in rats.

Male and female wild Norway rats (Rattus norvegicus Erxleben) and males and female albino outbred rats (Ipf:RIZ) were crossbred. The resulting animals (F1 hybrids) were the control, noninbred group (0% inbred). By systematic full-sib mating, two experimental groups (50 and 91% of inbred) were produced. Half of each group (both males and females) was exposed to physical stress (3 days of starvation and 3 hr of swimming). The other half of each group was anesthetized using ether to collect blood. The anterior pituitary hormone concentrations of prolactin (PRL), corticotropin (ACTH), and growth hormone (rGH) in blood serum were determined by the radioimmunoassay method. Significant relationships between the PRL, ACTH, and rGH concentrations in blood serum and the inbreeding coefficient were observed: A significant PRL content decrease in blood serum occurred (linear function) and the rGH and ACTH content diminished significantly rapidly (quadratic function). These changes were affected by an increase in homozygosity. Stress significantly influenced PRL, ACTH, and rGH concentrations as well. The sex of rats significantly determined PRL and ACTH content only. Hormone levels were also influenced by interactions between the factors studied (inbred level, sex, stress).

Adaptation, Physiological↗
PubMed2003

Inheritance of self-compatibility in almond: breeding strategies to assure self-compatibility in the progeny.

To assure self-compatibility in the progenies, three different crosses were conducted for the first time in an almond breeding programme: self-pollination (266 descendants from 30 families), crosses between parents sharing an S-allele (108 descendants from five families) and crosses with homozygous self-compatible parents (62 descendants from five families). Depending on the cross, self-compatibility in the progenies was determined by observing pollen tube growth (by means of fluorescence microscopy), stylar S-RNases analysis or allele-specific PCR. The results obtained fit with the accepted hypothesis of inheritance of self-compatibility and the three crossing strategies used ensured 100% of self-compatible descendants. These strategies increase the efficiency of the breeding programme and avoid the laborious task of evaluating this characteristic. From the breeding point of view, self-fertilisation and crosses between relatives tend to produce inbreeding. Furthermore, these methods reduce the possibilities of choosing the parental combination. The use of homozygous self-compatible parents does not have any of these disadvantages. As far as we know, this is the first time that allele-specific PCR has been used for early selection of self-compatible seedlings. The advantages and disadvantages of the three methodologies used to determine self-compatibility are discussed.

Crosses, Genetic↗
PubMed2003

Nuclear androdioecy and gynodioecy.

We formulate two single-locus Mendelian models, one for androdioecy and the other one for gynodioecy, each with 3 parameters: t the male (female) fertility rate of males (females) to hermaphrodites, s the fraction of the progeny derived from selfing; and g the fitness of inbreeders. Each model is expressed as a transformation of a 3 dimensional zygotic algebra, which we interpret as a rational map of the projective plane. We then study the dynamics for the evolution of each reproductive system; and compare our results with similar published models. In this process, we introduce a general concept of fitness and list some of its properties, obtaining a relative measure of population growth, computable as an eigenvalue of a mixed mating transformation for a population in equilibrium. Our results concur with previous models of the evolution of androdioecy and gynodioecy regarding the threshold values above which the sexual polymophism is stable, although the previous models assume constant the fraction of ovules from hermaphrodites that are self pollinated, while we assume constant the fraction of the progeny derived from selfing. A stable androdioecy requires more stringent conditions than a stable gynodioecy if the amount of pollen used for selfing is negligible in comparison with the total amount of pollen produced by hermaphrodites. Otherwise, both models are identical. We show explicitly that the genotype fitnesses depend linearly on their frequencies. Simulations show that any population not at equilibrium always converges to the equilibrium point of higher fitness. However, at intermediate steps, the fitness function occasionally decreases.

Algorithms↗
PubMed2000

Age-related appearance of tubular aggregates in the skeletal muscle of almost all male inbred mice.

Tubular aggregates (TAs) which have been recently observed in a few mouse myopathies are identical to those described in human diseases. In this study we show that TAs are also found in the skeletal muscle of almost all normal inbred mice strains. In these inbred strains of mice the presence of TAs is shown to be related to both age and sex. Nine different muscles were stained with the modified Gomori trichrome method to reveal the general morphology of the muscles. Anti-SERCA1 ATPase was used to confirm that the TAs were in fact accumulations of sarcoplasmic reticulum and anti-MyHC IIB to demonstrate that these accumulations were found exclusively in the type IIB muscle fibers. An ultrastructural study confirmed the observations revealed by light microscopy that the TAs were derived from the sarcoplasmic reticulum. TAs were never observed in female inbred mice and were only found in type IIB glycolytic muscle fibers of male inbred mice. Therefore when analyzing the effect of genetic knock out and knock in experiments on the muscle phenotype of transgenic mice one should be aware that the presence of these aggregates is a non-specific phenomenon induced by inbreeding.

Aging↗
PubMed2005

Segregation of microsatellite alleles in gynogenetic diploid Pacific abalone (Haliotis discus hannai).

Inheritance of 9 microsatellite loci was examined in 3 families of gynogenetic Pacific abalone Haliotis discus hannai produced by fertilizing eggs with UV-irradiated sperm followed by inhibition of the second meiotic division. The proportion of heterozygous progeny was used to estimate marker-centromere (M-C) distances. All loci conformed to Mendelian segregation in the control crosses when null alleles were accounted for. The absence of paternal alleles confirmed the gynogenetic origin of the offspring and indicated 100% success for 3 families. Estimated recombinant frequencies ranged from 0.10 to 0.60, which is lower than those observed in other gynogenetic diploid animals. The mean recombination frequency was 0.22, corresponding to a fixation index of 0.78 in one generation. This is 3.12 times the increase in homozygosity expected after one generation of sib mating (0.25), suggesting meiotic gynogenesis may be an effective means of rapid inbreeding in the abalone. M-C map distances for the 9 loci varied between 5 and 30 cM under the assumption of complete interference. The information about M-C distances will be useful for future gene mapping in H. discus hannai.

Animals↗
PubMed2004

Determination of genetic status in a closed colony of rhesus monkeys (Macaca mulatta).

The long-term management of breeding colonies requires some measure of genetic diversity in the animal population. For the maintenance of breeding colonies of monkeys used for biomedical research, known pedigrees supply precise data to determine the genetic status of colonies. We present data of genetic analyses in an old closed colony of rhesus macaques (Macaca mulatta) that was established in 1932 with 100 animals. For more than 40 years, the animals were kept on an isolated island and, in 1980, single-male breeding groups were established. A total of 333 DNA samples of these animals were typed to 20 microsatellite markers using multiplex PCR in order to verify inbreeding coefficient (alpha) and level of heterozygosity. We found an average heterozygosity of 64% and obtained alpha=-0.03293 (+/-0.00573). Our results indicate that the reproductive strategy used was effective because consanguineous breeding was avoided. A continuous genetic program must be carried out in order to obtain better quality primates for biomedical research.

Animals↗