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At least 1,261 records · Page 70Linked to original sources
PubMedDate not supplied

Genetic, epigenetic, dysgenetic and non-genetic mechanisms in tumorigenesis. II. Further delineation of the rate limiting step.

A not yet understood phenomenon in carcinogenesis is presented by the enormous species-specific and age-specific differences in cellular susceptibility to malignant transformation. Murine cells are 100,000 times fold more susceptible than human cells. A previous review article suggested the promotion phase as the key for this difference. Presently, a further analysis of literature data indicates that promotion results in the dedifferentiation of cells, which, in initiated cells, leads to an imbalanced regenerative growth of stem-cell-like cells. As aging results in the loss of adaptive functions and in a decreased response to growth stimuli, dedifferentiation of old cells is supposed to increase the imbalance of the regenerative growth for initiated cells and consequently to enhance the chance for immortalization of these cells. As immortalization is accompanied by chromosomal dysgenetics, malignant conversion by the appearance of secondary genetic events during multistage carcinogenesis is not just a matter of random chance for additional mutations, but is determined to some degree by the condition of the initiated target cell and to the species to which the target cell belongs.

Aging↗
PubMedDate not supplied

[Recent advances in genetics of epilepsy. Genetic of mitochondrial epilepsy].

INTRODUCTION: Recently the molecular basis of a series of clinical disorders associated with defects in the oxidative phosphorylation system (OXPHOS system) leading to ATP synthesis, the final pathway of mitochondrial energy metabolism, has been established. The polypeptide components of the OXPHOS system are codified in both nuclear and mitochondrial DNA. Therefore these mitochondrial diseases may be originated by mutations of genes found in both genetic systems. DEVELOPMENT: In recent years, several such neuromuscular diseases have been defined and associated with mitochondrial DNA mutations. One of the most striking of these is the syndrome of myoclonic epilepsy with ragged red fibres (MERRF), characterized by myoclonic epilepsy of maternal inheritance. This disorder is caused by a specific mutation on the mitochondrial tRNA(Lys) (position 8344), which gives rise to a reduction in the level of lysil-tRNA(Lys) and thus to premature termination of the translation of proteins codified in the mitochondrial DNA.

DNA, Mitochondrial↗
PubMed2001

[Genetic control of growth and development of yeast Saccharomyces cerevisiae cells. Phenotypic selection of mutants among strains of the Peterhof genetic collection].

Results of identifying phenotypes intrinsic to mutations of genes that regulate the activity of the signal transduction pathway of RAS-cyclic adenosinemonophosphate in six strains belonging to the Peterhof genetic collection of the yeast Saccharomyces cerevisiae are presented: an increase or decrease in the amount of the accumulated glycogen, resistance or sensitivity to heat shock and nitrogen starvation, and the growth and viability in media containing unfermentable carbon sources (potassium acetate, ethanol, and glycerol) at temperatures 30 and 70 degrees C. Collectively these phenotypic characteristics in five examined yeast strains can be interpreted as indicating disturbances in the activity of the RAS/cAMP pathway. However, the discrepancies revealed between cellular phenotypes in these strains and in the strains with a decreased or increased activity of the RAS/cAMP pathway did not allow them to be assigned to a particular functional activity group. The inconsistencies between phenotypes detected in this study may be prerequisites for the identification of new genes responsible for this signal transduction pathway or new mutations in the known genes that determine other phenotypic combinations.

Cyclic AMP↗
PubMed1975

Genetics of acheiropodia (the handless and footless families of Brazil). VI. Formal genetic analysis.

A genetic analysis is presented of data from 22 Brazilian sibships with cases of acheiropodia (the handless and footless families of Brazil). Segregation analysis performed using a 16K CDC 3100 computer showed a segregation frequency of .245 +/- .040, which is close to the expected value of .25. No sporadic cases were detected. The ascertainment of the probands was through multiple incomplete selection (pi = .55 +/- .07). The data are consistent with the hypothesis of an extremely rare autosomal recessive gene as the etiological factor in acheiropodia. Prevalence is estimated as 29 +/- 4, which is the same as the number of high risk cases; gene frequency equals .0009 +/- .0005, and the incidence at birth is 4 times 10(-6) by the indirect method or 7 times 10(-6) by the direct method. The frequency of heterozygotes at birth is assumed to be 0.18% (450 times the frequency of affected). Population size is approximately 10 million, and the number of founders on a unique-mutation hypothesis is estimated as about 500. All these estimates are first approximations and must be accepted with caution.

Abnormalities, Multiple↗
PubMed2003

[Genetic mapping of resistant gene to southern corn rust and the tagging analysis on different genetic background].

Southern corn rust (SCR) is a destructive disease in maize. The inbred line Qi319 is highly resistant to southern corn rust. SSR technique was employed to preliminary mapping of the resistance gene. Bulked segregant analysis revealed that two primers, phi 118 and phi 041, amplified polymorphic bands. SSR analysis on populations indicated the two primers were linked to the rust resistance gene, which was mapped on the short arm of chromosome 10. In addition, comparative analysis of the amplification bands among different populations revealed that the amplification products with the same primer in different populations were dissimilar. This result indicates that the genetic background may affect results of gene mapping and tagging. So, it is important to select suitable population to performing molecular marker analysis and gene mapping.

Basidiomycota↗
PubMed2003

How the analysis of genetic mutations can help us to solve basic problems in gerontology? I. Life extending genetic modifications in round worm C. elegans.

The results of recent molecular biological studies of aging and longevity confirmed substantial genetic contribution to the life span. The analysis of these findings showed substantial role of specific mutations in genes involved in regulatory processes on both the extra- and intracellular levels. We suggest that difference in responses of intact and mutant animals to the same set of environmental signals may be useful to clarify contribution of organism-environment interactions into the rate of aging, mortality and longevity of respective organisms. In our opinion such clarification is important for better understanding the origin of natural senescence and its dependence on external conditions.

Aging↗
PubMed1992

Genetic affinities of oceanic populations based on RFLP and haplotype analysis of genetic loci on three chromosomes.

Restriction fragment length polymorphisms at the renin and factor 13B loci located at chromosome 1q32-1q42 were studied in 14 ethnic groups in the west Pacific region. The allele frequencies were combined with previously described beta-globin and albumin-vitamin D binding protein haplotype frequencies and used to assess genetic affinities among eight major ethnic-geographic groups in this region. These population groups divide into two clusters with Australian Aborigines, Island Melanesians, and Highland Melanesians forming one cluster and east Asians, Southeast Asians, Micronesians, and Polynesians forming the other. The results indicate that Micronesians and Polynesians are derived from populations in Southeast Asia and that they originated independently of the Melanesian populations.

Beta-Globulins↗
PubMed2001

[Genetic complementation studies using genetically engineered mice have revealed the impact of phospholamban on progression of cardiomyopathy].

It has been suggested that dilated cardiomyopathy and end-stage heart failure result in multiple defects in Ca(2+) cycling. By genetic ablation of a muscle specific sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a) inhibitor, phospholamban, the broad phenotypes of murine model of dilated cardiomyopathy could be almost completely rescued. Thus, phospholamban inactivation or disruption of interaction between phospholamban and SERCA2a may provide a novel therapeutic approach for preventing the progression of heart failure.

English Abstract↗
PubMed1989

[Relation between genetic and non-genetic factors of individual susceptibility to silicosis].

The study was carried out at a number of industrial enterprises at risk of silicosis by means of the methodological approach based on the mathematical theory of image discrimination. It was shown that under the given conditions of dust exposure higher or lower probability of the development of silicosis and silicotuberculosis in an individual depended on the whole set of environment and endogenic factors, involving genetic predisposition to the disease as one of the leading factors. The impact of the above factors being similar irrespective of the type of the enterprise, their comparative contribution could be different. Thus reliable prediction of high probability of the disease development could be provided by means of the method of multifactorial analysis only as applied to specific conditions of the given enterprise. In spite of low prevalence of the genotype of silicosis- and silicotuberculosis-associated resistance, under the exposure to quartz dust, high probability of the disease development was predicted only in a number of cases if other individual symptoms were taken into account along the genotype. Therefore it became possible to identify the most susceptible persons at the stage of medical vocational selection.

Bronchitis↗
PubMed1987

[Expression of the quantitative trait radius incompletus, temperature effects and localization of mobile genetic elements in Drosophila. II. Mobile genetic elements Dm-412].

Two "selection" sub-populations (ris- and ris+), as well as two "temperature" ones (ric113 and ric149) were earlier developed from the control ric sub-population with interrupted vein of the fly wing. All five sub-populations were investigated for hybridization of MGE Dm-412 with drosophila polytene chromosomes in situ. The tree of similarity of MGE Dm-412 hybridization patterns was built by the methods of matrix clusterization. The sub-populations with the most resembling expressions of characters (ris- and ric113, ris+ and ric149) were found to be also most similar in patterns of MGE localization and their changes. Nonrandomness of these changes was shown, the similarity of patterns being demonstrated to be mainly the result of the changes. There is evidence that such effects cannot be accounted for by genetic drift and independent stochastic changes in MGE localization.

Animals↗
PubMed1985

Genetic transformation in Streptococcus sanguis. Effects on genetic transformation by culture filtrates of Streptococcus sanguis (serogroups H and W) and streptococcus mitis (mitior) with reference to identification.

Streptococcus sanguis (serogroups H and W) strains are frequently competent in genetic transformation. In a collection of 18 strains of S. sanguis isolated from blood cultures, 12 strains were spontaneously competent in transformation by streptomycin-resistant DNA, and three strains were induced to competence by the use of culture filtrates containing competence factor (CF). Culture filtrates from spontaneously competent S. sanguis strains only induced competence in transformation of strains of the same species. In addition to the three "constitutional" types of S. sanguis with regard to specificity of transformation previously reported (originally represented by the strain Challis, 13b and NCTC 7863), a possible fourth type, (represented by strain 21452) was found. Further studies are required to ascertain the role of these types. The "constitutional" types are characterized by the range of activity of their CF's. These specificities seem useful in identification of S. sanguis and its separation from S. mitis (mitior). Tests of spontaneously competent strains with culture filtrates from other competent strains showed variable effects on the transformation frequencies in different strains.

Bacterial Proteins↗
PubMed1980

[Transposon-induced genetic rearrangements in the chromosome of Vibrio El Tor and their application to the construction of the first genetic map of a cholera vibrio].

The specificity of integration of chloramphenicol resistance transposon (Tn9) into Vibrio El Tor chromosome was studied. As shown by the isolation of auxotrophs offerring various nitritional requirements, Tn9 displayed fairly low specificity in its interaction with the chromosome. When inserted into cholera vibrio chromosome, Tn9 induced secondary rearrangements of genetic material. Nutritional requirements were identified for the polyauxotrophic clones which resulted from the mutations in chromosome region adjacent to the insertion sites of Tn9 and Tn10. Based on these observations a preliminary map was constructed for certain regions of V. eltor chromosome.

Chromosome Mapping↗
PubMed1980

[Genetic control of pathways of pyrimidine metabolism in Aspergillus nidulans. 1. Isolation and genetic analysis of 6-azauracil resistant mutants].

147 mutants exhibiting the resistance to toxic effect of 6 azauracil have been isolated by nitrosoguanidine treatment from the wild strain of Aspergillus nidulans. This mutants have been divided into 11 phenotypic groups according to its cross-resistance to 5-fluoroderivatives of uracil, uridine and deoxyuridine. The genetic analysis has shown that all mutations of resistance are of nuclear origin and dominant nature, and they are distributed on six loci of the chromosome VIII.

Aspergillus nidulans↗
PubMed1983

[Genetic endocrine and ethological mechanisms of differential reproduction. I. A comparative genetic analysis of the basal testosterone level in the blood plasma and the relative weight of the testicles and accessory sex glands in male laboratory mice].

Comparative genetic study of the basal plasma testosterone level, relative weights of testicles, seminal vesicles, and preputial glands in 13 strains of laboratory mice showed significant interstrain differences in all indices studied. Under the relative rest condition, a significant positive interstrain (genotypic) correlation was found between basal blood testosterone level and the weight of preputial glands and testicles. At the same time, no intrastrain (paratypic) correlations between hormonal and morphometric indices under study were found. An important positive and highly significant paratypic correlative dependence was seen between the relative weights of seminal vesicles and preputial glands.

Animals↗
PubMed1980

[Use of the D7 strain of S. cerevisiae in the determination of environmental genetic risk. 2. Genetic effects of procarbazine].

Procarbazine was tested in vitro without and with S-10 fraction from mice liver (microsomal assay) using Saccharomyces cerevisiae strain D7, Salmonella typhimurium (strains TA 98, TA 100, TA 1535) and in vivo in Swiss albino mice (host mediated assay) using D7. Procarbazine without S-10 fraction was highly toxic and induced mitotic cross-over, gene conversion, and reverse mutation in D7. It had a toxic effect on all the Salmonella strains, but it did not induce any reverse mutations of the histidine mutants. In host-mediated assay using Saccharomyces, there was no genetic effect found in the indicator organism.

Animals↗
PubMedDate not supplied

Asthma and genetics. Lecture held at Interasma 93 (Jerusalem) during the Epidemiology and Genetic Session on October 28, 1993.

Hypersensitivity to environmental allergens has increased in the last years. Several authors have described the physicochemical properties, nucleotide and amino acid sequences, and also the three-dimensional structure of unknown allergens. The aim is to identify T- and B-cell epitopes and to understand the regulatory mechanism of the excessive immune response. The induction of specific IgE antibody production in genetically predisposed subjects is the characteristic allergens have in common. New molecular biological studies indicate that, especially in monosensitized subjects, a correlation exists between the HLA-D system and the allergen-specific IgE immune response.

Allergens↗
PubMed1975

Human genetic studies in areas of high natural radiation. VIII. Genetic load not related to radiation.

The genetic load disclosed by inbreeding has been analyzed in a multiple regression model for a population involving several localities in the state of Espírito Santo, Brazil. The inbreeding load has been estimated for number of pregnancies, abortions, stillbirths, children born alive, anomalies in general, sex ratio, infant mortality, post-infant mortality, and sterility and infertility of the couple. There was no evidence of either maternal or paternal inbreeding effects on the variables analyzed. The effect of inbreeding of the zygote was significant only for anomalies in general (B = 2.29 +/- 0.45) and infant mortality (B = 3.19 +/- 1.39). The latter result must be accepted with caution because of the many environmental causes affecting infant mortality. The B/A ratio suggested a predominantly mutational load for anomalies in general (B/A = 25), but with respect to infant mortality (B/A = 6), the ratio is regarded as an underestimate because of the environmental contribution to A and therefore not supportive of the segregational interpretation.

Abnormalities, Radiation-Induced↗
PubMed1977

A genetic and epidemiologic study of periodontal disease in Hawaii. II. Genetic and environmental influence.

In order to determine the relative influence of genetic and environmental factors in periodontal disease, path analysis has been applied to 241 nuclear families. Common family environment was represented by an index. The data failed to detect significant heritability, and common family environment proved to be a major determinant in the variation of periodontal health.

Adolescent↗