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PubMed1983

Maternal influence on growth of laboratory rats.

Data from 2,089 laboratory rats utilized in selection experiments were used to estimate maternal influence on growth from weaning (21 d) to 16 wk of age. Adjustment factors were calculated for the effects of sex, generation, litter size, inbreeding of the dam and inbreeding of the offspring on the body weights. The effect of line of sire was included in the analysis of variance models. Covariances among paternal half-sibs, full-sibs, offspring-dam, and individuals with the same maternal grandsire were equated to theoretical causal components of variance in a series of simultaneous equations. From these, estimates of heritability, maternal influence and other environmental influences on the weights of the animals were calculated. Estimates of additive genetic effects were negative at weaning and increased to positive intermediate values during postweaning growth. Maternal influence due to additive genetic effects was of primary importance at weaning and tended to diminish at later stages of growth. An antagonism was indicated between maternal environment and genes affecting the offspring's growth. Maternal influence is an important factor at weaning and during the postweaning growth of a litter-bearing species such as the laboratory rat.

Analysis of Variance↗
PubMed1989

Relationships of sire scrotal circumference to offspring reproduction and growth.

Reproductive and growth data were obtained on 779 and 564 yearling beef heifers and bulls, respectively, that had sires with yearling scrotal circumference data at the San Juan Basin Research Center, Hesperus, CO. Partial regression coefficients of reproductive and growth traits on inbreeding (FXC) and age of the individual and adjusted scrotal circumference of sire (SCSI) were obtained. Growth and reproductive traits of heifers and growth and breeding soundness traits of bulls were analyzed. Separate analyses for each sex were performed, but least squares models were similar. Models included fixed effects of breed, birth year (BY), age of dam (AOD) and the covariates FXC, age (day of birth in heifer analyses) and SCSI. Scrotal circumference of sire was adjusted for age, FXC, AOD and BY using values obtained in a separate analysis. Seminal traits improved as age increased, and there was a seasonal effect present for age of puberty. Inbreeding had a detrimental effect on reproductive traits. Partial regression coefficients for the reproductive traits on SCSI were: age of puberty, -.796 d/cm; age of first calving, -.826 d/cm; julian day of first calving, -.667 d/cm; julian day of second calving, .597 d/cm; most probable producing ability, .132 %/cm; percent sperm motility, -.74 %/cm; percent primary sperm abnormalities, .08 %/cm; percent secondary sperm abnormalities, .92 %/cm; percent normal sperm, -1.28 %/cm; total breeding soundness examination score, .28 units/cm and scrotal circumference, .306 cm/cm. A heritability of .39 was obtained for scrotal circumference.

Age Factors↗
PubMed1987

Autosomal recessive juvenile cataract in Hutterites.

Autosomal recessive inheritance of juvenile cataract is described amongst several related sibships of Lehrerleut Hutterites. The main features of the cataract include onset between three and seven years of age; rapid progression to maturity within one to three months; normal intelligence; no systemic associations, and no urinary reducing substances and normal erythrocyte galactokinase activity. Genetic analysis demonstrates the close relationship between parents of affected sibships with a coefficient of inbreeding of affected sibships of 0.0512. Estimates of heterozygote frequency within Lehrerleut Hutterites at 0.128 indicate that if current inbreeding practice continues additional cases can be expected.

Alberta↗
PubMed1988

Measuring genetic change in a dairy herd using a control population.

A selection experiment was conducted to assess the change in production resulting from selection with artificial insemination using a randomly maintained control. The experiment continued for 16 yr with approximately 20 lactations in each of the two breeding groups annually. Selection and control production was compared using 1) intraseason herdmate comparisons (weighted) and 2) mixed model maximum likelihood estimates of year-season effects (adjusted). The regressions of differences in milk yield on years for the two approaches were 110 kg for milk (weighted) and 108 kg for milk (adjusted), corrected for inbreeding. The regressions for fat were 3.9 kg for fat (weighted) and 4.2 kg for fat (adjusted). These regression coefficients were 1.6 and 1.5% of the least squares means for milk (6987 kg) and fat (259 kg), respectively. Definitive trends were not evident for differences between the two groups in percent fat, percent SNF, days open, final type classification score, or heart girth. Even with the limited numbers in the closed control population, inbreeding, and nonrandomness in culling of females or in the choice of dams of bulls appeared to have little impact on control mean during the 16 yr.

Animals↗
PubMed1992

Optimal effective population size for the global population of black and white dairy cattle.

The replacement of other black and white cattle strains by the North American Holstein breed, which itself is dominated by a small number of elite sires, has reduced the genetic diversity of the global population. Intense selection on a global basis leads to rapid genetic improvement but reduces effective population size. The optimal global effective population size was chosen to maximize the net present value of all future benefits from the breeding program. Two separate discount rates were used to reflect concerns about the long-term costs of small effective population size. This led to a higher optimal number of bull-sires than in past analyses. The optimum was sensitive to the magnitude of inbreeding depression and to the discount rates, but not to the variance caused by new mutations and the size of the world population. The genetic correlation between the breeding objectives of different AI studs controls the extent to which they all select the same sires of sons and, hence, affects the global effective population size. The prediction is made that different countries will select partially different sires, but genetically isolated strains will not reemerge. A better global breeding program is likely when selection of sires takes account of inbreeding depression and small genotype by environment interactions.

Animals↗
PubMed1999

Supply of genetic information--amount, format, and frequency.

The volume and complexity of genetic information is increasing because of new traits and better models. New traits may include reproduction, health, and carcass. More comprehensive models include the test day model in dairy cattle or a growth model in beef cattle. More complex models, which may include nonadditive effects such as inbreeding and dominance, also provide additional information. The amount of information per animal may increase drastically if DNA marker typing becomes routine and quantitative trait loci information is utilized. In many industries, evaluations are run more frequently. They result in faster genetic progress and improved management and marketing opportunities but also in extra costs and information overload. Adopting new technology and making some organizational changes can help realize all the added benefits of the improvements to the genetic evaluation systems at an acceptable cost. Continuous genetic evaluation, in which new records are accepted and breeding values are updated continuously, will relieve time pressures. An online mating system with access to both genetic and marketing information can result in mating recommendations customized for each user. Such a system could utilize inbreeding and dominance information that cannot efficiently be accommodated in the current sire summaries or off-line mating programs. The new systems will require a new organizational approach in which the task of scientists and technicians will not be simply running the evaluations but also providing the research, design, supervision, and maintenance required in the entire system of evaluation, decision making, and distribution.

Animals↗
PubMed1988

Comparison of pedigreed and nonpedigreed randombred control systems for use with artificial selection in the Japanese quail.

The performance characteristics of six replicate sublines of a randombred control, three pedigreed (P) and three nonpedigreed (NP), were studied to see if the NP mating system could be used as a method for maintaining a randombred control for selection experiments. Each subline was maintained with 32 single-pair matings, with 64 offspring placed each generation for each line. Brother X sister matings were avoided in the P but not in the NP system. The NP chicks were pedigreed in order to determine the exact numbers of brother X sister matings selected in that system, but pedigrees were not considered during selection. Records were collected on the numbers of matings producing offspring, the expected rate of inbreeding based on the effective population size, hatchability, egg production, egg weight, and the body weights of the males and females. Replicate lines in the P system had more matings that produced viable offspring, which resulted in larger effective population sizes, lower rates of inbreeding, and smaller average family sizes than those in the NP system. A number of significant differences were found between means of the replicate lines within system and between regressions of the traits measured in the individual lines on generation number. Most of these differences disappeared when the data from the three replicates within mating system were pooled and compared, suggesting that differences found between lines within system were due to random genetic drift due to restrictions in population size. It is suggested that the NP system can be used as an effective control procedure for Japanese quail breeding experiments, but that more than 32 mating pairs should be used for its maintenance in order to reduce the amount of genetic drift within the control population.

Animals↗
PubMed2026

Whole-Genome Sequencing Reveals Population Structure, Genetic Diversity, and Selection Signatures in Kazakh Dromedary and Bactrian Camels.

Understanding the genomic basis of environmental adaptation is essential for the conservation and genetic improvement of domestic camels. In this study, we investigated the population structure, genetic diversity, and genomic variation potentially associated with environmental adaptation of Kazakh dromedary and Bactrian camels using whole-genome sequencing. Whole-genome sequencing data were generated for Kazakh camels (15 dromedaries and 16 Bactrian camels) and integrated with 131 publicly available genomes representing camel populations from the Arabian Peninsula, Iran, Xinjiang, Inner Mongolia, and Mongolian wild camels. Population structure, genetic diversity, and genome-wide selection were evaluated using principal component analysis, ADMIXTURE, nucleotide diversity, linkage disequilibrium, runs of homozygosity, genomic inbreeding (FROH), and selection scans based on FST, θπ ratio, and XP-EHH. Population genomic analyses revealed clear differentiation between dromedary and Bactrian camels, whereas Kazakh camel populations exhibited higher nucleotide diversity (θπ = 1.307-1.551 × 10-3), and lower genomic inbreeding (median FROH: 0.037-0.056) than Arabian populations. Genome-wide selection analyses identified MC4R as the prominent candidate gene in Kazakh dromedaries and RYR1 as a prominent candidate gene in Kazakh Bactrian camels. Functional enrichment analyses highlighted pathways related to energy metabolism, thermogenesis, calcium signaling, skeletal muscle function, mitochondrial activity, and oxidative stress response. These findings provide new insights into genomic variation potentially associated with environmental adaptation in Kazakh camels and offer valuable genomic resources for future conservation, breeding, and evolutionary studies.

MC4R↗
PubMed1999

Sex ratios and genetic variation in a functionally androdioecious species, Schizopepon bryoniaefolius (Cucurbitaceae).

Androdioecy, coexistence of hermaphrodites and males, is an extremely rare breeding system in angiosperms. In the present study, Schizopepon bryoniaefolius (Cucurbitaceae) was confirmed to be functionally androdioecious based on observations of floral and pollen morphology and bagging experiments. Six out of the 11 studied populations consisted of only hermaphrodites, while the other five populations were androdioecious and the frequencies of males were consistently lower than those of hermaphrodites (5.5-28.3%). To understand the consequences of an androdioecious breeding system, genetic variation was estimated using four polymorphic allozyme loci. The degree of genetic differentiation among 11 populations was high (G(ST) = 0.688). Inbreeding coefficients (F(IS)) for all loci significantly deviated from zero. In particular, the F(IS) values averaged across the polymorphic loci in hermaphrodite populations were close to unity, suggesting that hermaphrodites are predominantly selfing in the absence of males. A significant negative correlation was found between the frequencies of males and inbreeding coefficients, indicating that outcrossing rates depend on the population sex ratio.

Journal Article↗
PubMed1999

[Maxillodental anomalies and consanguineous marriages].

Families of 549 probands and families of 123 probands with cleft lip and/or palate were examined in order to evaluate the relationship between marriages between close relatives and the incidence and structure of maxillodental diseases. Clinical and genealogical analysis of families of probands with maxillodental abnormalities and cleft lip and/or palate showed a significantly higher incidence of marriages between close relatives and an inbreeding coefficient in these families. Analysis of the population and familial incidence of maxillodental abnormalities and the inbreeding coefficient will help the physicians consulting such families more accurately evaluate the risk and improve the efficacy of prevention of such conditions.

Azerbaijan↗
PubMed1999

Enzyme polymorphism and genetic variability of laboratory populations of Phlebotomus papatasi, P. bergeroti, P. langeroni, and P. perniciosus.

Enzyme allomorph frequency and electrophoretic mobility were evaluated to clearly separate between morphologically similar sandfly species and to yield quantitative measures of their genetic similarity. Twelve enzyme systems were studied in laboratory colonies of Phlebotomus perniciosus, P. langeroni, P. papatasi, and P. bergeroti. Phlebotomus perniciosus and P. langeroni confirmed vectors of visceral leishmaniasis, were found to have fixed diagnostic allomorph differences at 3 enzyme loci (ICD-2, FUM, XDH). Phlebotomus papatasi, a known vector of cutaneous leishmaniasis and phleboviruses and P. bergeroti, a newly colonized suspected vector, were clearly differentiated from each other by a fixed allomorph at the MPI locus. Polymorphism at loci in these sandfly colonies ranged from 6.7% (P. perniciosus) to 43.7% (P. papatasi), with lowest levels seen in the older colonies. Expected heterozygosity was highest in P. papatasi, despite 33 generations of inbreeding, and comparable to that of P. bergeroti in its 7th generation. Against a scale of 0 for completely different, and 1.0 for identical genotypes, the enzyme data yielded indices of genetic identity (I) between P. perniciosus and P. langeroni and between P. papatasi and P. bergeroti of 0.783 and 0.737, respectively. These relatively high levels of genetic identity, paralleling similarities between species in morphology, inbreeding compatibility, and vectorial attributes, provide evidence of comparable and recent evolutionary divergence.

Animals↗
PubMed1999

[Epidemiology of hereditary diseases in Russian population].

The results of genetic epidemiological investigations performed in different regions of Russia are presented. The size of the population surveyed is over 1.5 million persons. The prevalence rates of autosomal dominant, autosomal recessive, and X-linked recessive disorders in Russia were first assessed. It has been shown that there is a clear genetic differentiation in the prevalence rates of autosomal recessive disorders for some of the populations studied. A correlation between random inbreeding and the prevalence of recessive and dominant disorders is not only significant, but very high and the differences in random inbreeding values are a main reason of this genetic differentiation in Russia's populations. A wide spectrum of hereditary diseases is found. This includes 115 autosomal dominant, 125 autosomal recessive, and above 30 X-linked recessive hereditary disorders. Only a small part of this spectrum occurs at a rate of 1:50,000 or greater; however, it is these disorders that determine a considerable proportion (more than 50%) of all forms of hereditary disorders. A small share of the hereditary diseases revealed shows a local accumulation, which can be also explained by a gene drift. The influence of the revealed regularities in the distribution of hereditary disorders in the populations of Russia on the organization of genetic service in the country is considered.

Genetic Diseases, Inborn↗
PubMed2000

Plant genetic diversity in the Canary Islands: a conservation perspective.

The Canary Islands are an Atlantic volcanic archipelago with a rich flora of ∼570 endemic species. The endemics represent ∼40% of the native flora of the islands, and ∼20% of the endemics are in the E (endangered) category of the International Union for Conservation of Nature. A review of allozyme variation in 69 endemic species belonging to 18 genera and eight families is presented. The average species-level genetic diversity (H(T)) at allozyme loci is 0.186, which is twice as high as the mean reported for endemics of Pacific archipelagos. Possible factors contributing to this higher diversity are discussed, but the reasons remain obscure. An average of 28% of the allozyme diversity within species resides among populations, indicating a high level of interpopulational differentiation. Studies of reproductive biology indicate that many of the endemic species are outcrossers. The high total diversity within species, the relatively high differentiation among populations, and the outcrossing breeding systems have implications for species conservation. Decreased population sizes in outcrossing species would promote biparental inbreeding and increase inbreeding depression. The relatively high proportion of allozyme diversity among populations indicates that the most effective strategy for preserving genetic variation in species is to conserve as many populations as possible. The genetic diversity in many Canary Island endemics is endangered by: (1) overgrazing by introduced animals, such as barbary sheep, goats, mouflons, rabbits, and sheep; (2) interspecific hybridization following habitat disturbance or planting of endemics along roadsides or in public gardens; (3) competition with alien plant species; and (4) decline of population size because of urban development and farming.

Journal Article↗
PubMed1975

Experimental liver diseases.

The use of animal models in the experimental production of liver diseases similar to those of man is still in its infancy. There is a need to discover new models more closely related to counterpart syndromes in man in the fields of hepatorenal syndrome, neonatal jaundice, Wilson's disease, cholelithiasis, viral hepatitis, biliary atresia, and cirrhosis, to mention only a few. With the continued indiscriminate inbreeding of companion animals as well as the planned inbreeding of laboratory animals, there is little doubt that many more will soon be available. The current availability of mutant rats and sheep with bilirubin transport defects has allowed for a better understanding of how organic anions are transported by the liver. Many other currently available experimental animal models herein briefly reviewed have been only superficially studied. It is the intent of this chapter to provide for post-doctoral students an appreciation for the many animal model systems available for experimental hepatic research.

Alkaloids↗
PubMed2001

Patterns of allozyme diversity in the threatened plant Erigeron parishii (Asteraceae).

Thirty-one occurrences of Erigeron parishii, a narrowly endemic plant threatened by mining, were sampled for allozyme diversity. This taxon held considerable genetic variation at the 14 allozyme loci surveyed. Species (e.g., alleles per locus [A] = 4.3 and proportion of polymorphic loci [P] = 0.64) and population (e.g., A = 2.15 [SD = 0.3] and P = 0.53 [SD = 0.12]) genetic diversity measures were higher than expected for narrowly endemic plant taxa. The proportion of polymorphic loci and numbers of alleles per locus indicated that E. parishii has not experienced severe or long-lasting population bottlenecks. Within-population f indicated low to moderate levels of inbreeding. Populations were only moderately differentiated (theta-p = 0.12), suggesting either that there is substantial gene flow among populations or that populations have not been isolated long enough to detect effects of genetic drift. There was no significant differentiation among populations in different vegetation types nor was there a relationship between genetic distance and geographic distance among sites. Continued fragmentation by mining activities would isolate populations, disrupting gene flow, exacerbating loss of diversity, and increasing inbreeding in the remaining fragments. Protection of large, interconnected populations throughout the range of the taxon is warranted to maintain processes that have sustained the observed diversity.

Journal Article↗
PubMed2001

[Genetic epidemiological study of populations in three regions of Chuvashia Republic].

Comprehensive population genetic and medical genetic studies were performed in three raions (districts) of Chuvashia. The population of these districts is more than 90% Chuvash. About 70% of the families that completed reproduction had two or three children. The proportion of families with four or more children was 18%. The duration of generation was 27.6 years. The differential fertility and differential mortality indices in the Chuvash population were estimated at 0.33 and 0.076, respectively. The total index of differential selection was 0.403, which is typical of modern urbanized populations. Mean values of local inbreeding calculated from Malecot's model of isolation by distance were 0.00124 and 0.00377 for the urban and rural populations, respectively, of the districts studied. The prevalence rates of autosomal dominant (AD), autosomal recessive (AR), and X-linked diseases were found to be 0.47, 0.52, and 0.35 per 1000, respectively, in the urban population and 1.62, 1.14, and 0.31 per 1000, respectively, in the rural population. Significant correlation between the local inbreeding and prevalence rates of AD and AR diseases was found. A total of 43 AD and 43 AR diseases were identified. Some of them were not found in previous studies on other populations.

Adolescent↗
PubMedDate not supplied

[Seed set analysis in three amaranth species (A. cruentus, A. caudatus, and A. lividus) under self- and cross-pollination conditions].

Seed set was analyzed in three amaranth species (A. cruentus, A. caudatus, and A. lividus) under conditions of self- and cross-pollination during four vegetative periods in 1995-1998. It was demonstrated, that the populations of these species are polymorphic for the breeding system and that they consist of self-sterile and self-fertile plants. The populations were composed mostly of self-sterile plants and the percentages of self-fertile plants were only 34.7%, 18.7%, and 12.5% for A. cruentus, A. caudatus, and A. lividus respectively. The level of self-fertility was high in the first year of isolation, it sharply decreased during the subsequent years of selfing, due to inbreeding effect. Seed set under self- and cross-pollination is determined by species-specificity of the plants, influence of conditions of their growth, and inbreeding depression. Conditions of growth had the strongest influence on seed set. Index of its influence varied from 0.53 to 0.87 for the cross-pollinated plants and from 0.13 to 0.68 for the self-pollinated ones. Analysis of variance demonstrated a weak effect of the interaction of these factors. Spearman's rank correlation demonstrated a highly significant agreement between the seed set values for the self- and cross-pollinated plants of A. cruentus and A. lividus. The lines derived from the three amaranth species varied widely in the seed set values under both self- and cross-pollination conditions.

Amaranthus↗
PubMed2001

[Analysis of diversity of autosomal-recessive diseases in Russian populations].

The diversity of autosomal recessive (AR) diseases was studied in six Russian regions: the Kirov, Kostroma, and Bryansk oblasts; Adygea Republic; Krasnodar krai, and Marii El Republic (in the latter region, the Mari and Russian ethnic groups were studied separately). In total, more than 1.5 million people were studied. The spectrum of the AR diseases included 101 nosological forms; the total number of the affected subjects was 942. For all diseases, the prevalence rate in the region where they were found and the mean prevalence rate in the total population studied were calculated. Only seven AR diseases had prevalence rates of 1:50,000 or higher; however, this group contained about 50% of the patients. About half of the AR diseases (66) had an extremely low prevalence rate (1:877,483). Eleven diseases exhibit local accumulation. Accumulation of some or other diseases was only observed in four out of seven populations studied (Marii El, Adygea, and the Kirov and Bryansk oblasts). To determine the cause of the local accumulation of some diseases in populations, correlation analysis of the dependence of accumulation of hereditary diseases on the genetic structure of the populations studied was performed. The accumulation coefficients for AR and autosomal dominant (AD) diseases and the mean values of random inbreeding (Fst) in individual districts were calculated for all populations studied. The coefficients of the Spearman rank correlation between the accumulation coefficient and random inbreeding (Fst) were 0.68 and 0.86 for the AD and AR diseases, respectively. The correlation between the accumulation of AD and AR diseases was 0.86. The relationships found indicate that the diversity of AD and AR diseases, as well as the genetic load, distinctly depended on the population genetic structure and were largely determined by genetic drift.

Genes, Recessive↗