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At least 271 records · Page 15Linked to original sources
PubMed2000

Platelet monoamine oxidase activity in alcoholics with and without a family history of alcoholism.

A number of studies point at platelet monoamine oxidase (MAO) activity being reduced in alcoholics with a family history of drinking, this being a possible vulnerability marker for alcoholism. To test this hypothesis, we examined a group of recently detoxified alcoholics with high (n = 25) and low genetic loading for alcoholism (n = 28) and a group of healthy controls (n = 21). Clinical assessments were made using the SCID II interview for psychiatric disorders, the Family History Assessment Module and the Semi-Structural Assessment of Genetics in Alcoholism, a questionnaire especially designed for genetic studies. Platelet MAO activity with and without ethanol stimulation and the percentage of MAO activity with ethanol did not differ between groups. The only significant difference was a lower inhibition of MAO activity with ethanol in alcoholics both with and without a family history compared to controls. In patients with antisocial personality traits, platelet MAO activity was also not found to be different from other alcoholics. Our findings question the hypothesis of reduced platelet MAO activity to be a possible vulnerability marker for alcoholism.

Adult↗
PubMed1987

[Differential diagnosis and different etiologies of monopolar and bipolar phasic psychoses].

Monopolar and bipolar phasic psychoses can be differentiated not only on the course but also on the symptom pattern. This applies also to the euphoric forms which usually are still assigned to Manic-depressive illness. The differential diagnosis is presented. Aetiology is completely different in the monopolar and the bipolar phasic psychoses. Manic-depressive illness has a hereditary basic, whereas in the monopolar ("pure") forms loading is very low. Particularly few psychoses among the relatives have been found in the euphoric forms which demonstrates their independency for if they would belong to Manic-depressive illness they necessarily would show the heavy genetic loading of this bipolar illness. In the pure phasic psychoses external causes were detected when we focused on the sibships in which the probands had grown up. The euphoric patients had relatively many older siblings, the depressive ones relatively few older siblings. A similar difference was found in two cycloid psychoses. Transcultural observations as well as shifts in the incidence rate of the psychoses in our times confirmed our results. Prophylactic measures can be derived.

Bipolar Disorder↗
PubMed1977

Microgeographic differentiation of chromosomal and enzyme polymorphisms in Drosophila persimilis.

We studied microgeographic and temporal genetic differentiation in natural populations of Drosophila persimilis with respect to chromosome inversion and enzyme polymorphisms. Both inversion frequencies and allozyme frequencies varied significantly over short distances. Neither differed significantly between morning and evening collections. Because several studies of the dispersal behavior of this species have been performed, we attempt to fit the observed data to mathematical models which relate dispersion to random genetic drift and to spatially varying selection coefficients. We conclude that the observations are due at least partly to behavioral differences among genotypes. i.e., habitat preferences. These results have implications for genetic load theory and models of selection in heterogeneous environments.

Animals↗
PubMedDate not supplied

[Alteration of polymorphic systems of Centaurea scabiosa L. under chronic irradiation].

Isoenzyme and morphological polymorphism alteration in populations of perennial grass Centaurea scabiosa L. (scaly cornflower) has been studied. These populations exist on the territory of East Ural Radioactive Trace more than 40 years and are chronically exposed to beta-irradiation. Directional shift of allele frequencies on the loci Per1, Pgi2, Sod1, Lap has been detected. The fact of accumulating genetic load by chronically irradiated populations has been demonstrated. Possible reasons of discovered alterations are discussed. The analysis of the obtained data shows that the irradiated populations have greater similarity with one another than with a control, but relation between genetic distances and accumulated doses hasn't been revealed. The hypothesis is that an extra factor--gene flow from a "clean" territory influences the genetic structure of irradiated populations.

Asteraceae↗
PubMed2025

Characterisation of the Historic Demographic Decline of the British European Polecat Population.

The European polecat (Mustela putorius) has a widespread distribution across many countries of mainland Europe but is documented to be declining within these ranges. In Britain, direct persecution led to a severe decline of the polecat population during the 19th century. Unlike European mainland populations, it is now recovering across much of its former British range. The genomic and conservation implications of such a severe demographic decline, followed by the current recovery, have still to be characterised in the European polecat in Britain. Here we carry out population-level whole-genome analyses of 65 polecats from Britain (Wales and England) and the European mainland. Our analyses reveal that Welsh polecats show genetic variability from both English and European polecats, while British polecats as a whole exhibit signs of genetic isolation from mainland European populations. We also reconstructed the demographic history of the Welsh polecat to quantify the magnitude of the bottleneck. Our analyses confirmed the drastic decline of the Welsh polecat's effective population size, with a severe genetic bottleneck around 30-40 generations ago (1854-894). We investigated whether whole-genome diversity reflected this demographic event and found that Welsh polecats had significantly less genetic diversity than English polecats, but not European polecats. Runs of homozygosity and genetic load present in Welsh and English polecat genomes also indicated recent historic inbreeding. Our findings suggest that the increase in the British polecat population size may be attributed to admixture events. Additionally, we demonstrate that the Welsh polecat constitutes a genetically distinct population, which could be crucial for the overall conservation of European polecats by preserving unique genetic diversity.

Genetics, Population↗
PubMed2006

An evolutionary cost of separate genders revealed by male-limited evolution.

Theory predicts that intralocus sexual conflict can constrain the evolution of sexual dimorphism, preventing each sex from independently maximizing its fitness. To test this idea, we limited genome-wide gene expression to males in four replicate Drosophila melanogaster populations, removing female-specific selection. Over 25 generations, male fitness increased markedly, as sexually dimorphic traits evolved in the male direction. When male-evolved genomes were expressed in females, their fitness displayed a nearly symmetrical decrease. These results suggest that intralocus conflict strongly limits sex-specific adaptation, promoting the maintenance of genetic variation for fitness. Populations may carry a heavy genetic load as a result of selection for separate genders.

Animals↗
PubMed2001

Environmental stress and mutational load in diploid strains of the yeast Saccharomyces cerevisiae.

The negative effect of permanent contamination of populations because of spontaneous mutations does not appear to be very high if judged from the relatively good health of humans or many wild and domesticated species. This is partly explained by the fact that, in diploids, the new mutations are usually located in heterozygous loci and therefore are masked by wild-type alleles. The expression of mutations at the phenotypic level may also strongly depend on environmental factors if, for example, deleterious alleles are more easily compensated under favorable conditions. The present experiment uses diploid strains of yeast in which mutations arise at high rates because a mismatch-repair protein is missing. This mutagenesis resulted in a number of new alleles that were in heterozygous loci. They had no detectable effect on fitness when the environment was benign. A very different outcome was seen when thermal shock was applied, where fitness of the mutation-contaminated clones was lower and more diverse than that of the nonmutagenized clones. This shows that the genetic load conferred by spontaneous mutations can be underestimated or even overlooked in favorable conditions. Therefore, genetic variation can be higher and natural selection more intense when environmental conditions are getting poorer. These conclusions apply, at least, to that component of variation that directly originates from spontaneous mutations (as opposed to the variation resulting from the history of selection).

Biological Evolution↗
PubMed1991

A genetic study of male sexual orientation.

Homosexual male probands with monozygotic cotwins, dizygotic cotwins, or adoptive brothers were recruited using homophile publications. Sexual orientation of relatives was assessed either by asking relatives directly, or when this was impossible, asking the probands. Of the relatives whose sexual orientation could be rated, 52% (29/56) of monozygotic cotwins, 22% (12/54) of dizygotic cotwins, and 11% (6/57) of adoptive brothers were homosexual. Heritabilities were substantial under a wide range of assumptions about the population base rate of homosexuality and ascertainment bias. However, the rate of homosexuality among nontwin biological siblings, as reported by probands, 9.2% (13/142), was significantly lower than would be predicted by a simple genetic hypothesis and other published reports. A proband's self-reported history of childhood gender non-conformity did not predict homosexuality in relatives in any of the three subsamples. Thus, childhood gender nonconformity does not appear to be an indicator of genetic loading for homosexuality. Cotwins from concordant monozygotic pairs were very similar for childhood gender nonconformity.

Adoption↗
PubMed1983

Developmental switches in reiterated genes may reduce the rate of age changes in DNA.

The possible role of the redundancy of genetic information in the regulation of the ageing rate has been discussed in several works. However, it was shown recently that the gene reiteration in most cases is represented by families of similar, but not identical genes. Their expression usually related to the different stages of development and when "early" embryonic or fetal genes are active, the "late" or adult genes are repressed. It is known that the DNA repair needs double stranded structure of DNA which is usual for inactive genes. Genes which are being transcribed and active are repressed by unwound, relaxed DNA which is less protected by the DNA repair enzymes. Aging of genetic information in somatic cells can be, therefore, considered as stage specific and alterations of "early" embryonic and fetal genes do not constitute the genetic load which influences the ageing rate of differentiated cells.

Aging↗
PubMed2003

[Formal genetic findings in attention-deficit/hyperactivity-disorder].

Twin, family and adoption studies have led to a solid understanding of the contribution of both genetic and environmental factors to the development of attention deficit/hyperactivity disorder (ADHD). We review recent studies under consideration of both methodological aspects and relevant findings. Heritability estimates in the range of 0.6 - 0.8 surpass those for most other child and adolescent psychiatric disorders. First degree relatives have elevated rates for ADHD, affective disorders, conduct disorders and substance abuse and dependency. The ADHD subtype of the index patient does not predict the subtype of other family members affected with ADHD; hence non-genetic factors seemingly account for this intrafamilial variability. Because the familial rates for ADHD are not higher in families of female in comparison to male index patients, there is no indication that the genetic loading is higher in affected females. Recently, rater effects have been discussed broadly: Whereas the heritability estimates are uniformly high independent of the informant (mother, father, teacher), the correlations between quantitatively rated symptoms are low between different informants. Knowledge of the formal genetic aspects of ADHD is a prerequisite for understanding the results of recent molecular genetic studies.

Adolescent↗
PubMed1980

The evolution of multiple mating behavior by honey bee queens (Apis mellifera L.).

A model is presented showing that natural selection operating at the individual level can adequately explain the evolution of multiple mating behavior by honey bee queens. Group selection need not be invoked. The fitness of a given female genotype is a function of the number of sex alleles in the population, the number of matings by an individual female and the specific parameters that determine the relationship of brood viability to individual fitness. Even though the exact relationship is not known, it is almost certainly not linear. A nonlinear relationship between worker brood viability and fitness and a significant genetic load associated with the sex-determination system in honey bees are the essential components of this model.

Animals↗
PubMed1997

Body mass index and family histories in type II diabetic propositi and preliminary observations on the transmission of diabetes in polygamous families.

We studied family histories of diabetes mellitus in the first-degree relatives of 356 type II diabetic propositi in whose families monogamy is practiced. Positive family histories were noted in 32% of the propositi: parental 20%, sibling 14%, and offspring 0.6%. In 11 pedigrees with conjugal diabetic parents, 33% (18/55) of their offspring were diabetic. Paternal influence was significantly higher than maternal influence (43 of 62 vs. 19 of 62, Z = 2.86, p < 0.01). The presence or absence of sibling history did not depend on the body mass index in the propositi. We also studied pedigrees of 10 propositi in whose paternal families polygamy is practiced. In these families also a trend toward greater paternal influence was noted. We conclude that (1) a family history of diabetes is present in one-third of diabetic propositi, (2) paternal influence is stronger than maternal influence in the transmission of diabetes, (3) sibling history for diabetes has no relation to the body mass index of the propositi, (4) prevalence of diabetes is higher in the offspring of conjugal diabetic parents, and (5) studies in polygamous families are a new approach that may help to quantify the genetic load transmitted from a parent when there is heterogeneity in the spouses.

Adult↗
PubMed1998

Stable equilibria in multilocus genetic systems: a statistical investigation.

A data base of gametic distributions at a stable equilibrium for genetic systems with up to five diallelic loci was created by numerically iterating equations for the dynamics of gametic frequencies in multilocus systems under selection. For a given number of loci, iterations were conducted for 4000 random sets of genotypic fitnesses, 6 values of recombination, and 10 different initial distributions. The data base was used to investigate the following properties of stable equilibria maintaining a polymorphism in a given number of loci that are expected a priori, i.e., without any constraints on fitnesses of genotypes: probability for a fitness set to yield a such equilibrium; probability for a random trajectory to converge to a such equilibrium; genetic load at a such equilibrium. The expected number of simultaneously stable equilibria, and the fraction of genome maintained polymorphic were also investigated as well as some parameters expected at an equilibrium maintaining all loci polymorphic. One of the most important findings is that multilocus genetic systems have a potential for maintaining a polymorphism in a large number of loci under selection without an input of new genetic variation.

Genetic Linkage↗
PubMedDate not supplied

Sensorineural hearing loss in children.

During the past three to four decades, the incidence of acquired sensorineural hearing loss (SNHL) in children living in more developed countries has fallen, as a result of improved neonatal care and the widespread implementation of immunisation programmes. The overall decrease has been accompanied by a relative increase in the proportion of inherited forms of SNHL. The contribution made by one gene in particular, GJB2, to the genetic load of SNHL has strongly affected the assessment and care of children with hearing loss. These changes in the incidence of SNHL have not been seen in children living in less developed countries, where the prevalence of consanguinity is high in many areas, and both genetic and acquired forms of SNHL are more common, particularly among children who live in poverty. Focused genetic counselling and health education might lead to a decrease in the prevalence of inherited SNHL in these countries. Establishment of vaccination programmes for several vaccine-preventable infectious diseases would reduce rates of acquired SNHL. Although the primary purpose of such programmes is the prevention of serious and in many cases fatal infections, a secondary benefit would be a reduction in disease-related complications such as SNHL that cause permanent disability in survivors.

Child↗
PubMed1998

[The status and developmental outlook of the priority scientific trend in environmental protection].

Scientific researches carried out in the area of environmental sanitation are closely related to the principal lines of activity in industry and farming of Ukraine. The main task of research work is establishing principles, criteria and methods of comprehensive assessment of injury to health secondary to environmental contamination. With the purpose of identification of the real physical and chemical environmental factors load that human body experiences, an inventory has been made at the Ukrainian Scientific Research Centre for Hygiene of carcinogen sources, with the concept having been worked out of creation of the integrated system for control of safe NPS operation, and a concept proposed of genetic monitoring, and of state genetic load surveillance service in different regions of Ukraine, taking account of the degree of environmental pollution.

Environmental Health↗
PubMed1975

On the relationship between spontaneous mutation rates in vivo and in vitro.

Recent estimates of spontaneous mutation rates in man, in which previous sources of bias are corrected, indicate that the average is about 3 x 10(-7) per locus per generation, a much lower figure than is generally accepted. Assuming 100 to 1000 cell divisions between each gametic union, this information predicts that cellular mutation rats should be in the order of 10(-9) per locus per generation. Since none of the mutation rates measured in cultured cells are this low (average for seven characters equals 7 x 10(-7)), the size of mutation rates in cultured cells cannot be used to substantiate the claim of epigenetic inheritance. Furthermore, this information suggests that in multicellular organisms the germinal tissue is sequestered from mutagenic insult or subjected to selection against mutational damage so as to keep the genetic load of a species at a tolerable level. Alternatively, cell culture environments may present an extremely abnormal situation to somatic cells, thus elevating the mutation rate.

Cells, Cultured↗
PubMed2001

Inbreeding depression in two populations of Arenaria uniflora (Caryophyllaceae) with contrasting mating systems.

I used parallel family-structured crossing designs to investigate the relative performance of self and outcross progeny in selfing and predominantly outcrossing populations of the annual plant Arenaria uniflora. The selfer population experienced much lower inbreeding depression (delta = 0.05 +/- 0.02 SE) than the outcrossers (delta = 0.19 +/- 0.02 SE). The negative association between genetic load and selfing rate suggests that purgable partially recessive alleles are the primary source of inbreeding depression, as does its late expression in both populations. Inbreeding depression in the selfer population, which naturally consists of highly inbred lines, was used to calculate the mean dominance (h = 0.33) and incidence rate (U = 0.30) of deleterious mutations. In the outcrosser population, significant variation among individuals in the expression of inbreeding depression may reflect lineage-specific differences in inbreeding history or, more probably, random variation in mutational load. The low (<< 0.5) inbreeding depression of outcrossers suggests that the maintenance of a mixed mating system in some A. uniflora populations and the evolution of nearly cleistogamous self-pollination in others may reflect local pollinator-mediated selection for selfing rather than the constant 3:2 genetic advantage invoked by many models.

Analysis of Variance↗
PubMed1997

Reinforcement of genetic coherence: a single-locus model.

Genetic coherence and genetic separation are the outcome of evolutionary mechanisms which maintain genetic variation within populations through recombination on the one hand, and which divide this variation via speciation between reproductively (recombinatorically) more or less isolated populations on the other. While mechanisms of speciation have received considerable attention in biology, their counterpart, mechanisms of genetic coherence, are addressed only implicitly, if at all. Usually, genetic coherence is intuitively associated with the forces maintaining genetic polymorphisms and thus potential for flexible adaptational reaction of populations. However, so far no models seem to exist which explain the evolution of genetic coherence as the natural counterpart of genetic separation or speciation. In this paper a single-locus model is analyzed, in which a mutant allele is introduced into a resident stable diallelic polymorphism, and where this allele is equivalent to one of the resident alleles in all respects with the exception of mating relations. The conditions for replacement of the resident allele by its selectively equivalent mutant are obtained with reference to the associated mating relations. It turned out that for heterozygote advantage the mutant replaces the selectively equivalent resident allele if it increases the mating preferences for carriers of other alleles. The evolution of lower such preferences requires heterozygote inferiority, which confirms the Wallace effect of speciation (by reinforcement). It is argued that this observation suggests that non-selective constituents of the mating system form the section of the genetic system that is responsible for moderating the genetic load implied by adapting selection while simultaneously securing the adaptational potential embodied in the resident allelic variation. Mating systems thus serve the preservation of adaptability.

Adaptation, Physiological↗