Genetic Effects of Low-Dose Chronic Irradiation of Developing Seeds of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> (L.) Heynh.

A six-year study, starting in 1987, was focused on the frequency of embryonic lethals and chlorophyll mutations that arose in developing seeds of Arabidopsis thaliana growing at sites varying in the level of radioactive contamination in the 30-km control region of the Chernobyl Atomic Power Plant. The dose rate of chronic irradiation varied from 200 μR/h to 2.4 R/h. To study the genetic effects of various levels of radioactive contamination, the frequency of mutations arising in a particular generation was determined and the irradiation dose was estimated for the given generation. The dose dependence of the mutation frequency proved to follow a power function with a power less than unity, suggesting a relatively high effect for low-dose irradiation. Possible explanations of this phenomenon are discussed.     

Redefining the Critical Value of Significance Level (0.005 instead of 0.05): The Bayes Trace

Biology Bulletin - In 2017, a group of the leading mathematical statisticians published a paper-manifesto having an extremely simple sense: the common critical level of p-values should be decreased...     

Genetic effects of low-dose chronic irradiation of developing seeds of Arabidopsis thaliana Heynh

A six-year study, starting in 1987, focused on the frequency of embryonic lethals and chlorophyll mutations that arose in developing seeds of Arabidopsis thaliana growing at sites varying in the level of radioactive contamination in the 30-km control region of the Chernobyl Atomic Power Plant. The dose rate of chronic irradiation varied from 200 microR/h to 2.4 R/h. To study the genetic effects of various levels of radioactive contamination, the frequency of mutations arising in a particular generation was determined and the irradiation dose was estimated for the given generation. The dose dependence of the mutation frequency proved to follow a power function with a power less than unity, suggesting a relatively high effect for low-dose irradiation. Possible explanations of this phenomenon are discussed.     

Association of <Emphasis Type="Italic">MAOA-uVNTR</Emphasis> Polymorphism with Subjective Well-Being in Men

Quality of life and one’s subjective evaluation of one’s own happiness and well-being are the conventional focus of psychology and sociology. However, a genetic factor has recently been found to affect the subjective evaluation of well-being. The contribution of heredity to a personal level of happiness and life satisfaction has been estimated at 30–50% in twin studies. Individual genes associated with these traits have been identified, but the available data are rather discrepant. In this work, alleles of the monoamine oxidase A gene (MAOA) were tested for association with well-being components, such as happiness, health, dangers of living environment, and stress, in Russian men. Trait assessments were based on questionnaires filled out as part of the World Values Survey. It is shown that, among the uVNTR-3R allele carriers, the proportion of men who have high levels of stress, feel unhappy, and live in unsafe environments is lower. The results are discussed in the context of the gene plasticity concept, which provides a possible explanation for how expression of genes related to behavior changes in different environmental conditions.     

Genetic risk assessment of the joint effect of several genes: Critical appraisal

When assessing the combined action of genes on the quantitative or qualitative phenotype we encounter a phenomenon that could be named the “paradox of the risk score summation.” It arises when the search of risk allele and assessment of their combined action are performed with the same single dataset. Too often such methodological error occurs when calculating the so called genetic risk score (GRS), which refers to the total number of alleles associated with the disease. Examples from numerous published genetic association studies are considered in which the claimed statistically significant effects can be attributed to the “risk score summation paradox.” In the second section of the review we discuss the current modifications of multiple regression analysis addressed to the so called “n ? p problem” (the number of points is much smaller than the number of possible predictors). Various algorithms for the model selection (searching the significant predictor combinations) are considered, beginning from the common marginal screening of the “top” predictors to LASSO and other modern algorithms of compressed sensing.     

Remote consequences of a chronic radiation for the population of Hypochoeris maculata L growing on the territory of East-Ural radioactive trace

The caryological study has been carried out on Hypochoeris maculata L. plants growing on the East-Urals radioactive trace. Two Hypochoeris maculata L. populations have been observed. The experimental population grows in contaminated area. 90Sr contamination density is 55 MBq/m2, 137Cs contamination density is 2.5 M Bq/m2. The control population grows in radionuclide-free area. Both in the experimental and in the control populations the plants have been detected bearing extra B-chromosomes in their karyotype. But their frequency was higher in the experimental population than in the control one. In the experimental population the plants with main A-chromosome set karyotype changes have been met in 9 families out of 30 families observed. In the control population one such family has been detected out of 27 families observed. Two plants with karyotype changes in both chromosome sets have been detected in one family of the experimental population, which indicates a possibility of sibling species appearance in the experimental population.     

Allelic variants of polymorphic genes associated with a higher frequency of chromosome aberrations

Genotypic associations were studied for the frequency of chromosome aberrations in human peripheral blood lymphocytes. Cytogenetic analysis (1000 metaphase plate per individual) and genotyping at 19 sites of genes involved in detoxification and DNA repair were performed in a sample of 83 Chernobyl liquidators and a matched control sample of 96 volunteers. In either sample, the frequency of chromosome aberrations was higher in carriers of the minor alleles of the XPD gene (sites 2251T > G and 862G > A) and the positive genotypes of the GSTM1-GSTT1 genes. The highest frequency of chromosome aberrations was observed in carriers of a combined genotype including at least one minor allele of the XPD sites + at least one insertion in the GSTM1-GSTT1 genes. The high-risk genotype, which had a prevalence of 64%, was strongly associated with a higher frequency of chromosome aberrations in both volunteers (OR = 6.9, P = 0.008) and Chernobyl liquidators (OR = 5.6, P = 0.002).