[Age Dynamics of Telomere Length in Endemic Baikal Planarians].

Age-related changes in telomere length (TL) in somatic tissues are not limited only to shortening. It is known that many organisms show different TL dynamics. Such species specificity indicates the complexity of the mechanisms involved in the regulation of TL. Owing to their morphological, physiological, and ecological features, Baikal planarians are an interesting model for studying the TL dynamics and the factors influencing it in comparison with species living outside Baikal. In this work, we investigated telomerase activity and age-related changes in TL in three endemic species of planarians from the Dendrocoelidae family. Two species are giant deep-water species (7-12 cm long, Sorocelis hepatizon and Rimacephalus arecepta), and one is a coastal shallow species (1 cm long, Baikalobia guttata). In addition, we investigated the telomere biology in another small Siberian species from the Planariidae family (2 cm in length, Phagocata sibirica), which is not found in Baikal. TL and telomerase activity were determined using real-time PCR and the TRAP method. Three types of age-related TL dynamics were detected with active telomerase: (1) TL shortening at the juvenile stage of development and subsequent maintenance (R. arecepta, Ph. sibirica), (2) gradual TL shortening during ontogeny (S. hepatizon) and (3) cyclic dynamics of TL (B. guttata). Thus, the changes of TL in the studied planarians does not have an obvious connection with body size, habitat depth, phylogenetic relationship and is probably a consequence of species features in the regulation of telomerase activity.

[Length and structure of telomeric DNA in three species of Baikal gastropods (Caenogastropoda: Hydrobioidea: Benedictiidae)].

The structure of telomeric repeat (TTAGGG)n was determined and the length of telomeric DNA (tDNA) was measured in three species of gastropods from the family Benedictiidae that are endemic to Lake Baikal. Fluorescence in situ hybridization (FISH) confirmed the localization of a telomeric repeat at the chromosome ends. The sizes of tDNA in "giant" eurybathic, psammo-pelobiontic species Benedictia fragilis and shallow water litho-psammobiontic species B. baicalensis with medium shell sizes were similar (16 ± 2.9 and 15 ± 2.1 kb, respectively), but they had a greater length than that of the shallow water spongio-litobiontic species Kobeltocochlea martensiana with small shells (10.5 ± 1.5 kb). We discuss tendencies in age-related changes in tDNA length in snails and a possible mechanism for maintaining tDNA size in ontogeny.

[Telomere length and phylogenetic relationship of Baikal and Siberian planarians (Turbellaria, Tricladida)].

Dynamics of the telomeric DNA (tDNA) and the phylogeny of the Baikal and Siberian planarians have been studied based on the analysis of the 18S rDNA and beta-actin gene fragments. A relationship between tDNA and the planarians size has been demonstrated. Giant planarians with a minor exception have longer tDNA than little planarians. Phylogenetic affinity between the species that have the stretched tracks of tDNA, big size and similar habitats may indicate possible role of tDNA in the development of the indefinite regenerative capacity of planarians.

[Interspecific variability of telomeric DNA length in some Siberian and endemic Baikal planarians (Plathelminthes, Tricladida)].

The length of the telomeric DNA in nine species of planarians inhabiting Lake Baikal and one Siberian species from Baikal rivers was determined using Southern hybridization. According to preliminary estimations, it varied in the range of 25-30 kb (Rimacephalus arecepta, Rimacephalus pulvinar, Sorocelis hepatizon, Sorocelis nigrofasciata, Protocotylus sp., Baikalobia guttata, Bdellocephala baikalensis, Phagocata sibirica) and 50 kb (Baikaloplana valida, Baikalobia copulatrix). It is the first estimation of the values of telomeric region lengths for Baikal free-living flat worms.

[Medico-genetic counselling of the relatives of patients with type I diabetes mellitus]. / Mediko-geneticheskoe konsul'tirovanie rodstvennikov bol'nykh sakharnym diabetom I tipa.

Population-genetic surveys show that for the relatives of patients with type I diabetes mellitus (the 1st degree of kinship) a risk of developing the same type of diabetes is 2-5%. Tables of repeated risk of developing diabetes mellitus (DM) of type I for persons with a different number of relatives affected by this type of DM were calculated on the basis of analysis of 2000 family histories of DM patients (a random sampling). A risk of developing this disease is in direct correlation with the number of sick and healthy relatives and their age. The presence of patients with type II DM in a family does not influence the risk of developing type I DM. Risk assessments are of prognostic rather than diagnostic value. The effectiveness of medico-genetic counselling can be increased with the help of various genetic markers, associated with type I DM. Risk assessment must lay the basis of a follow-up of persons with aggravated heredity by investigating immunological, hormonal and metabolic derangements in them.

[Genetic-epidemiologic analysis of uterine myoma: assessment of repeated risk]. / Genetiko-épidemiologicheskii analiz miomy matki: otsenka povtornogo riska.

The results of myoma uteri family analysis are presented. Average estimates of family risks were: 26.6% for proband's sisters, 19.73% for proband's daughters (up to 44-years-old), 15.81% for proband's mothers. The estimate of heritability of the disease calculated according to the sibs data was 0.792 +/- 0.018, which points to the essential role of hereditary factors in the development of myoma uteri. The table of recurrence risk was calculated on the basis of the data obtained which may be used for forming risk groups in the course of mass physical examination.

[Genetic analysis of the predisposition to uterine myoma. Prevalence and morbidity]. / Geneticheskii analiz struktury predraspolozheniia k miome matki. Rasprostrannost' i zabolevaemost'.

Prevalence of uterine myoma (MU) was estimated in several Moscow districts. The overall average estimate of the MU prevalence is 2.45% among women of all groups. The prevalence MU estimates increase with the age, its maximum value reaching 8.31% at the age of 50 years. The morbidity risk estimates increased with the age as well, the maximum value being 2.98% at the age of 40-44 years. The value of "cumulative" morbidity risks, i. e. the probability to be affected, is 9.74% for a population living long enough, this value being based on the age-specific estimates of morbidity risks. Taking into consideration the autopsy data, indicating that frequency of MU, including small myomatous nodes, is 20%, the conclusion is made that MU is manifested by clinically expressed disturbances (urging a woman to address to a doctor) in 50% of cases only. Epidemiological data obtained are to be used later for genetic analysis of familial data on MU.

[Possibility of the current segregation analysis to discriminate between monogenic and multifactorial types of inheritance of traits. The effect of the structure of family data on model robustness and power of the analysis]. / Issledovanie vozmozhnosti sovremennogo segregatsionnogo analiza razgranichivat' monogennyi i mul'tifaktorial'nyi tipy nasledovaniia priznakov. Vliianie struktury semeinykh dannykh na ustoichivost' modelei i moshchnost' analiza.

The influence of sampling designs for robustness of the autosomal major locus model and the multifactorial model as well as possibility of segregation analysis to discriminate these models was studied. Nuclear families and 3-generation pedigrees were considered. It was found that robustness of models increased, when the size of sibships in nuclear families grows and when configuration of pedigrees is complicated. The resolution power of the analysis is always increased with size elevation of sibships, the highest effect of the analysis being observed for sibships of the size 3 or 4. Consideration of new generations is only advisable, if attracting sibs of these generations, the resolution power being increased, provided that the parameters of models are of high value.

[The possibility of modern segregation analysis to discriminate monogenic and multifactorial types of the inheritance of traits. The reliability of models and the power of the analysis]. / Issledovanie vozmozhnosti sovremennogo segregatsionnogo analiza razgranichivat' monogennyi i mul'tifaktorial'nyi tipy nasledovaniia priznakov. Ustoichivost' modelei i moshchnost' analiza.

Using computer simulation of family data sets within segregation analysis limits the comparative research of the autosomal major locus model (MLM) and the multifactorial model (MFM) which described the basic types of inheritance of the alternative traits (affected--nonaffected) has been conducted. Robustness of models (statistical aspect) and the power of the analysis (its possibility to discriminate MLM and MFM) are tested. It is shown that permissible level of relative errors for estimated population's frequency is increased, when the values of parameters of models are increased (with decrease of sporadic cases' portion). The power of the analysis is the greatest in the field of greatest robustness of models: the higher the parameters of models, the portion of sporadic cases being low, the stronger the power of the analysis. MFM satisfactorily describes family distribution given by additive MLM. On the contrary, if the MLM corresponds to the multifactorial traits, this model is additive. It is shown that the possibility of the analysis to reject alternative model is decreased when determination of model grows down.

[Multivariate approach to calculating the recurrence risk in families with multifactorial diseases]. / Mnogomernyi podkhod k vychisleniiu povtornogo riska v sem'iakh pri mul'tifaktorial'nykh zabolevaniiakh.

To resolve one of the main theoretical problems of genetic counselling, namely, calculation of the recurrence risk for common diseases, a multivariate approach is suggested, based on the multifactorial model. The model suggests partially different liability for several diseases or various forms of a disease. The specified recurrence risk for each family can be calculated with the account of different morbidity rates for different sexes and the degree of kinship to proband. The input data for computer calculations are: population incidence of diseases, their heritabilities as well as genetical and environmental correlations between the diseases. Our method is illustrated by calculation of the recurrence risk for diabetes mellitus (DM) and bronchial asthma (BA), each of which may be subdivided into several forms. It is proposed that the nature of genetic correlations is different for two diseases. The phenotypic forms of DM are genetically independent, whereas the forms of BA have a common genetic basis.

[Medico-genetic study of the population of the Kostroma region. III. Inbreeding coefficient and its dynamics in rural populations and small towns]. / Mediko-geneticheskoe izuchenie naseleniia Kostromskoi oblasti. Soobshchenie III. Koéffitsient inbridinga i ego dinamika v sel'skikh populiatsiiakh i gorodakh raionnogo masshtaba.

Analysis of the inbreeding coefficient, its structure and dynamics in rural and urbanized populations of the Kostroma province was performed. The coefficient of inbreeding was estimated for the "old" and "new" villages via migration and isonymy, the values being 0.001185; 0.000786 and 0.001341; 0.000682, respectively. It follows from these data that there is a good agreement between the values of the inbreeding coefficient estimated by two different methods and that this coefficient is diminished doubly in "new" villages. The coefficient of inbreeding in small towns was estimated via isonymy. It is 0.000704 in ancient and 0,000229 in modern towns. The decrease in the inbreeding coefficient was more pronounced in towns, as compared to villages.