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PubMed1993

Reduction of leaky lymphocyte clones producing immunoglobulins and thymic lymphocytic leukemia by selective inbreeding of SCID (severe combined immunodeficiency) mice.

Selective inbreeding of C.B17-scid/scid mouse pairs showing undetectable IgG and IgM has been carried out in order to reduce the mortality of mice by early occurrence of thymic lymphocytic leukemia and abnormal lymphocyte clones producing immunoglobulins, both of which inhibit the successful heterotransplantation of normal and neoplastic human tissues. Although the majority of C.B17-scid/scid mice showed undetectable (< 1 microgram/ml) or low level (< or = 25 micrograms/ml) of serum IgG and IgM, some produced abnormally high concentrations of IgG and IgM (> 25 micrograms/ml). The incidence of such mice showing higher levels of IgG was very high at F1 and F2 generation (10/55, 18.2%), but significantly low after the F3 generation (18/446, 4.0%, p << 0.001). Although leukemia incidence was very high at F4 to F5 generations (8/40, 20.0%), death from leukemia was not observed early in life (4-6 months after birth) at F7 to F10 generations (0/36, 0%, p < 0.01) and was very low during the age of 6-10 months after the F8 generation (11/66, 16.7% at F4 and F5 vs 4/93, 4.3% at F8-10), p < 0.01). Scid mice improved by the selective inbreeding will provide an invaluable experimental system for the heterotransplantation of normal and neoplastic human tissues.

Animals↗
PubMed1975

Theory of inbreeding and covariances between relatives under full-sib mating in diploids.

A generation matrix theory of full-sib mating is developed in which 13 mating "classes" are distinguished according to identity of genes in individuals mated and identity of genotypes as belonging to homozygous, parental, or offspring sets. The 13 times 13 matrix reveals some properties of the full-sib mating system not shown by previous work. The eigenvalues and a set of eigenvectors for the generation matrix, and the general solution for the frequencies of mating classes among descendants of an original mating of genotypes ab times cd, are given. The genotypic array of descendants in an arbitrary generation is also given. A new formula is derived for the coefficient of inbreeding in generation n + m in terms of coefficients of inbreeding in earlier generations. An algorithm is presented for calculating the probability of a given situation of identity of alleles carried by two individuals given only the indices of their own respective generations and the generation of their most recent common ancestor. The application of such probabilities to obtaining covariances between relatives in a full-sib mating system, under the assumptions of independence and non-interaction among loci, is illustrated. All results are shown to agree with previous work in special cases. All possible full sib, generation n - 1 parent-generation n + m offspring, and generation n uncle-generation n + m nephew covariances for 1 less than n + m less than or equal to 8 are obtained using the given algorithm.

Alleles↗
PubMedDate not supplied

[Gutteral pouch tympany in German warmblood foals: influence of sex, inbreeding and blood proportions of founding breeds as well as estimation of heritability].

The objective of the present study was to analyse the importance of the influences of sex, inbreeding coefficient, proportion of genes of the original breeds and the additive genetic contribution to the occurrence of guttural pouch tympany in foals belonging to German Warmblood breeds. Foals affected by guttural pouch tympany were ascertained in the Clinic of Horses, School of Veterinary Medicine Hannover. This data set comprised 22 German Warmblood foals with guttural pouch tympany, which were patients of the Clinic for Horses between 1994 and 2001. Information on the pedigrees and all available relatives of these patients allowed us to group the affected foals into five families with a total of 289 animals. Female foals were significantly more often affected by guttural pouch tympany. The difference was 16.6% in favour of female foals. The size of the inbreeding coefficient was not important for the occurrence of guttural pouch tympany. The proportion of the genes of the breeds Arabian, Thoroughbred and Trakehner were not significantly different from a randomly selected sample of 10% of foals born in the same birth years and the same region. The heritability estimates for the frequency of guttural pouch tympany using a threshold model was 0.81 +/- 0.16. This is the first report that could show a genetic component responsible for guttural pouch tympany in horses.

Animals↗
PubMedDate not supplied

[The investigation of the influence of cryopreservation and inbreeding on the variability of morphological characteristics of the evening-primrose biennial (Oenothera biennis L.)].

The effect of deep freezing of seeds at -196 degrees C (-320.8 degrees Fahrenheit) and inbreeding on the morphological characteristics of the evening-primrose biennal (Oenothera biennis L.), such as the size of plant parts and the amount of fruits, cauline nodes, and generative and vegetative shoots was investigated. The variation coefficients for these characteristics after treatment with low temperatures and inbreeding were calculated. It was shown that the characteristics of plant size show a low and a middle level of variability in the control group. The variation curves for these characteristics are similar to normal distribution curves. After stresses they slightly change or remain invariant. Large adventive shoots show a high level of variability. The distribution of the results in this case significantly differs from the normal. The branching of plants changes after both stress factors: the amount of all kinds of shoots decreases by half or even more.

Cryopreservation↗
PubMed2005

The effect of self-fertilization, inbreeding depression, and population size on autopolyploid establishment.

The minority cytotype exclusion principle describes how random mating between diploid and autotetraploid cytotypes hinders establishment of the rare cytotype. We present deterministic and stochastic models to ascertain how selfing, inbreeding depression, unreduced gamete production, and finite population size affect minority cytotype exclusion and the establishment of autotetraploids. Results demonstrate that higher selfing rates and lower inbreeding depression in autotetraploids facilitate establishment of autotetraploid populations. Stochastic effects due to finite population size increase the probability of polyploid establishment and decrease the mean time to tetraploid fixation. Our results extend the minority cytotype exclusion principle to include important features of plant reproduction and demonstrate that variation in mating system parameters significantly influences the conditions necessary for polyploid establishment.

Computer Simulation↗
PubMed2006

A model of the evolution of dichogamy incorporating sex-ratio selection, anther-stigma interference, and inbreeding depression.

Historically, explanations for the evolution of floral traits that reduce self-fertilization have tended to focus on selection to avoid inbreeding depression. However, there is growing support for the hypothesis that such traits also play a role in promoting efficient pollen dispersal by reducing anther-stigma interference. The relative importance of these two selective pressures is currently a popular topic of investigation. To date, there has been no theoretical exploration of the relative contributions of selection to avoid the genetic costs of self-fertilization and selection to promote efficient pollen dispersal on the evolution of floral traits. We developed a population genetic model to examine the influence of these factors on the evolution of dichogamy: the temporal separation of anther maturation and stigma receptivity. Our analysis indicates that anther-stigma interference can favor dichogamy even in the absence of in-breeding depression. Although anther-stigma interference and inbreeding depression are the key forces driving the initial evolution of dichogamy, selection to match the timing of pollen dispersal to the availability of ovules at the population level becomes a more potent force opposing the further evolution of dichogamy as the extent of temporal separation increases. This result may help to explain otherwise puzzling phenomena such as why dichogamy is rarely complete in nature and why dichogamy tends to be associated with asynchronous flower presentation.

Biological Evolution↗
PubMed1986

Inbreeding and the balance between selection and mutation.

The first half of the paper described the structure of a large population caused by subdivision and inbreeding. Then, in the second half, it shows the structure of a population does not play any role in determining the incidence of the recessive genotype (aa). The latter is determined entirely by the ratio of the mutation rate to the selection coefficient. The recessive gene frequency, however, depends much on the structure of the population. The effect of relaxing inbreeding and subdivision on the rise and fall (rather the fall and rise) of the recessive gene frequency has been discussed.

Gene Frequency↗
PubMed1982

[Study of an isolated West Indies population. II. Estimation of the inbreeding value (author's transl)].

Saint-Barthélémy, a small island near Guadeloupe, has been isolated since the 18th century. A first estimation of genetic size at each generation gives an estimation of the present inbreeding value due to random genetic drift. It is of the order of half a per cent. A census of matings between closely related persons (first or second cousins), during the three last generation may provide an estimation of the inbreeding value related to choice of mates based on relatedness using Sutter's equation of apparent consanguinity. This estimation is of the same order (0.8%) but is restricted to the cumulative effect of random genetic drift and non-random mating between relatives during these three last generations. A full estimation of remote consanguinity at present time requires a detailed analysis of genealogies.

Consanguinity↗
PubMed1980

Detection of inbreeding effects by the chi-square test on genotypic and phenotypic frequencies.

The problem of detection of inbreeding effects by the chi-square goodness-of-fit test is investigated. The noncentrality parameter of the limiting chi-square distribution is considered as a function of the inbreeding coefficient in two models: (1) a gene locus with m codominant alleles and (2) the generalized ABO model. Previous results by Ward and Sing and by Chakraborty and Rao were based on inadequate statistical reasoning. In the first model, the resulting noncentrality parameter is identical with that found by Ward and Sing. For the second model, the limiting noncentrality parameter is found to be zero.

ABO Blood-Group System↗
PubMed1997

The spectre of inbreeding in the early investigation of heredity.

Inbreeding introduced by R. Bakewell (1725-1795) in England for creating new animal races, was opposed by animal breeders on the Continent on religious grounds, and was soon introduced in sheep breeding for wool production in Moravia. In 1790-1840 the protagonists repeatedly rejected 'the spectre of inbreeding' and included consanguineous matching in scientific breeding. In 1836 they even formulated the research question of heredity and next year proposed the inductive method for its investigation. The achievements of sheep breeders instigated German breeders to reject the dogma of the constancy of race and to elaborate the theory of individual potency. Treating heredity as the force under the influence of environment they could not solve the enigma. The question formulated in 1836 was explained in 1865 by Gregor Mendel. His theory was not perceived by animal breeders as well as by biologists up to the end of the century.

Animals↗
PubMed1998

[Variability of pericentromeric chromatin in chromosome 2 of ovarian nurse cells during inbreeding in Anopheles atroparvus V.Tiel].

We investigated the variability of pericentromeric chromatin of chromosome 2 in ovarian nurse cells (trophocytes) in two laboratory lines of malaria mosquito Anopheles atroparvus V. Tiel and in their hybrids. One line had been raised by means of sib inbreeding, the other kept at constantly high population density. The inbreeding was shown to result in an increased percentage of chromosomes bearing an achromatinic zone in the centromeric region, which resulted in chromosome breakage. Toxicological tests demonstrated an increase in the sensitivity of the progeny of females with abnormal morphotypes of chromosome 2 to the entomopathogenic bacterium Bacillus thuringiensis israelensis. The appearance of the achromatinic zone is attributed to local chromatin underreplication accompanying chromosome polytenization. Possible reasons for this phenomenon and its implication for adaptation are discussed.

Animals↗
PubMed1991

Inbreeding in Finland.

We have compiled data on the frequency of first-cousin marriages in Finland using royal dispensation records for the time period 1810-1872 and national population statistics for the time period 1878-1920. For the earlier period, 0.315% of Finland's marriages were contracted between first cousins (2,331 of 739,387). During the second time period, 0.174% of Finland's marriages took place between first cousins (1,325 of 761,976). These figures, which yield average kinship coefficients of 0.00020 and 0.00011, respectively, show that the level of inbreeding in Finland due to first-cousin marriage has been quite low. An analysis of individual parishes shows that first-cousin marriages are, on average, substantially less frequent than predicted by a random-mating model. In order to evaluate determinants of first-cousin marriage, several predictive variables have been examined: parish ethnic composition (proportion of Swedish and Finnish speakers), husband's occupation (graded into 6 socioeconomic levels), geographic distance between spouses' premarital residences, population density, parish endogamy, and urban vs. rural residence. Various logistic and linear regression models were analyzed in which consanguinity was the dependent variable. The best predictors of consanguinity were ethnic composition and occupation. The other variables were not in general significant predictors. These results show that many of the "mate availability" factors that would be predicted theoretically to account for consanguinity variation (population density, geographic isolation, urban vs. rural residence) do not. Instead, the best predictors of consanguinity at the first-cousin level are cultural factors such as ethnicity and occupation. Evaluation of cultural variables can provide a greatly enriched interpretation of complex biosocial phenomena such as inbreeding.

Consanguinity↗
PubMed1982

Influence of inbreeding on reproductive performance, ejaculate quality and testicular volume in the dog.

An established foxhound colony employing an outbreeding and inbreeding program was evaluated to assess the influence of increased homozygosity on overall reproductive performance and ejaculate quality. A total of 14 outbred and four inbred male dogs were naturally bred to 544 outbred and 51 inbred bitches, respectively. Mean conception rate and total number of puppies whelped and number born alive were greater (P<0.01) in outbred compared to inbred lines. Duration of gestation and number of puppies surviving from birth to weaning were not different between outbred and inbred groups. Ejaculate quality of studs also appeared affected by genotype with outbred males producing a greater (P<0.025) average sperm count/ejaculate and sperm count/ml of ejaculate. Ejaculate volume, % motility of spermatozoa and testes volume, although not significantly different, also favored the outbred compared to inbred sires. These results: 1) indicate that a breeding program utilizing dogs with inbreeding coefficients ranging from .125-.558 can experience reduced reproductive performance; 2) suggest that a portion of the infertility associated with conception may be attributed to the male, since inbred studs produced lower quality ejaculates compared to outbred counterparts.

Journal Article↗
PubMed2003

Inbreeding and road effect zone in a Ranidae: the case of Agile frog, Rana dalmatina Bonaparte, 1840.

Inbreeding has often been invoked in the extinction of local populations. In eleven western France populations of Agile frog studied, observed heterozygosity was significantly lower than expected in all cases, giving new evidence of such a depression in small populations. It especially occurred in ponds located near an highway rather than in undisturbed populations (FIS = 0.544 and 0.315, respectively). Thus, our results argue for a "road effect zone". Discussing about road distance and conservation policies, we propose that roads are directly involved in inbreeding and in local extinction. Thus, road construction ought to consider conservation management.

Animals↗
PubMed1987

Twinning and inbreeding in India: the fraternal component.

It is suggested that the rise in a population depends not only on the nu number of females per thousand males, their fecundability, and the survival of offspring (mean live births), but also on the genetic background or inbreeding status of the fetuses. Abortions and stillbirths add to the interference. A hypothetical formula has been devised (Formula: see text), where Mb = mean birth rate, G = growth percentage of population sample from preceding Census, F = inbreeding coefficient, Sa = Stillbirths + abortions, and Sr = Sex ratio. It is intriguing that the product, being termed Fraternal Component (FC), is found to be almost equal to the DZ twinning rate of the population sample. Should that be confirmed, one could perhaps estimate the DZ twinning rate by an altogether new approach.

Adult↗
PubMed1991

An estimation of inbreeding from isonymy in the historical (1734-1810) population of the Quebrada de Humahuaca (Jujuy, Argentina).

The method of isonymy to estimate inbreeding is applied to the historical population of the Quebrada de Humahuaca (Province de Jujuy, Republic of Argentina). Data from the baptismal records of the Parochial Church of Humahuaca from 1734 to 1810 were grouped into two periods, 1734-72 and 1773-1810. The analysis was carried out twice: (a) using the surnames exactly as they were registered; (b) combining homonymous surnames which were pronounced or spelt in a similar way. The random and non-random components of inbreeding have been investigated through different methods. There were no significant differences between the results of the two analyses, nor between the expected and observed isonymy. The value of F lies somewhere between those for offspring of first cousins once removed and second cousins once removed. There is a tendency for F and its components to increase through time. It is concluded that the high altitude aboriginal population of Humahuaca Parish must have behaved as a panmictic unit.

Argentina↗
PubMed1995

Sex linked versus autosomal inbreeding coefficient in close consanguineous marriages in the Basque country and Castile (Spain): genetic implications.

Pedigree structures of 161 uncle/niece-aunt/nephew and 4420 first cousin consanguineous marriages registered during the 19th and 20th centuries in two large and very different Spanish regions have been analysed and their genetic consequences evaluated. The frequencies of the different pedigree subtypes within each degree of relationship were quite similar in both populations despite significant heterogeneity in inbreeding patterns. The mean X-linked inbreeding coefficient (Fx) for each type of cousin mating was calculated and compared to that expected for autosomal genes (F). The effect of genealogical structure on the Fx/F ratio was compared to different cultural populations worldwide. Preferentiality and avoidance of close consanguinity along with specific types of pedigrees are discussed on the basis of premarital migration and sociocultural rules still deeply rooted in certain human groups. By admitting that the observed Fx coefficient is usually higher than F in most human populations some remarks have been made in terms of population genetic risk.

Chromosome Aberrations↗
PubMed2002

Estimation of inbreeding from ecclesiastical dispensations: application of three procedures to a Spanish case.

The inbreeding coefficient of a population, estimated from ecclesiastical Roman Catholic dispensations, results from the relative contribution of different degrees of relationships (uncle-niece, first cousin, etc.). The interpopulation comparisons of consanguinity patterns may be obscured by the fact that in 1918 the Roman Catholic Church norm regulating the closest marriageable kinship was modified, limiting the application for an ecclesiastical dispensation to relatives of third degree (second cousins) or closer. Depending on the length of the period before or after the change of regulation, coefficients and rates may differ. Deviation of frequencies for multiple marriages may also occur. The aim of the present paper is to determine how the chosen procedure based on ecclesiastical dispensations may affect results, regarding the inbreeding coefficient, the consanguinity rate, the structure of consanguinity and the close/remote kinship ratio. As a sample case, information from the Gredos mountain range (central Spain) has been used.

Catholicism↗