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V V Efremov

Publications and source records attributed to V V Efremov.

At least 19 recordsLinked to original sources
PubMed2005

[Effective size of the early-run sockeye salmon Oncorhynchus nerka population of Lake Azabach'e, Kamchatka Peninsula evaluation of the effect of interaction between subpopulations within a subdivided population].

The effect of subdivision on the effective size (Ne) of the early-run sockeye salmon Oncorhynchus nerka population of Lake Azabach'e (Kamchatka Peninsula) has been studied. The mode of this effect is determined by the relative productivity of the subpopulations and its magnitude, by the rate of individual migration among subpopulations and genetic differentiation. If the contributions of subpopulations (offspring numbers) are different, genetic differentiation can reduce the Ne of the subdivided population. At equal subpopulation contributions, genetic differentiation always increases the Ne of the subdivided population in comparison with a panmictic population. We have found that all sockeye salmon subpopulations of Azabach'e Lake produce equal offspring numbers contributing to the next generation. The genetic differentiation between sockeye salmon subpopulations is low, and the subdivision increases the Ne of the early-run race with reference to the sum of the effective sizes of the subpopulations by as little as 2%.

Animals↗
PubMed2005

[Equilibrium between genetic drift and migration at various mutation rates: simulation analysis].

Rates of approach to equilibrium values of F(ST)/R(ST) at various mutation rates and using different mutation models (K-allele model KAM and stepwise model SMM) were analyzed numerically for the finite island model and the one-dimensional stepping stone models of migration, using simulation. In the island model of migration and the KAM mutation model, the rate of approach to the equilibrium F(ST) value was appreciably higher and the equilibrium value was almost twofold lower at micro (mutation rate) = m (migration rate) than at micro << m. In the one-dimensional stepping stone model of migration and the KAM model of mutation, the mutation rate significantly affected both the rate of approaching F(ST) equilibrium and the equilibrium value. In both island and one-dimensional stepping stone models and SMM, R(ST) was not influenced by various mutation rates. The rate of approach to the equilibrium values of both F(ST) and R(ST) was lower for the stepping stone model than to the island model. RST was rather resistant to deviations from the SMM mutation model.

Genetic Drift↗
PubMed2004

[Effective size of subpopulation of the early run sockeye salmon Oncorhynchus nerka from Azabach's Lake (Kamchatka): effect of density on variance of reproductive success].

Using Parensky's approach for estimating the number of breeding pairs, we determined effective subpopulation size Ne in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka) in 1977 through 1981. On average (over years and populations), biased sex ratio decreased Ne by 7% as compared to the number of fish on the spawning sites (Ni). High density reduced the Ne/Ni ratio by 62-66% because some fish were excluded from spawning. Dominance polygyny as compared to monogamy and random union of gametes could reduce Ne by about 17%.

Animals↗
PubMed2004

[Effective size of subpopulations in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka): the effect of relative reproductive success of different-year cohorts].

The effect of variation in reproductive success of cohorts of different year of birth (within generation) on the effective subpopulation (breeding group) size in early-run sockeye salmon Oncorhynchus nerka from Azabach'e Lake (Kamchatka). The annual variation in census size and overlapping of year classes reduced the ratio of the effective subpopulation size to the census size by 7 to 88% in different subpopulations. The total effect of the variance of reproductive success in individual years and the variance of reproductive success of different cohorts reduced the effective size/census size ratio by 68-96%.

Animals↗
PubMed2004

[The rate of approach to the equilibrium value of F(ST) in island and one-dimensional stepping-stone models of migration].

The rate of approach to the equilibrium value of FST was analyzed numerically for the finite island and one-dimensional stepping-stone models using computer simulation. For both models, this rate was shown to decrease with decreasing migration rate among subpopulations but in the case of the stepping-stone model, it takes thousands rather than tens of generations to reach the equilibrium. Unlike the island structure of migration, in the stepping-stone model an increase in the subpopulation number reduces the rate of reaching the equilibrium state.

Algorithms↗
PubMed2001

[Genetic variability and differentiation of populations of chum salmon Oncorhynchus keta (Walbaum) from the southern Russian Far East].

Allozyme variation of populations of chum salmon Oncorhynchus keta from southern Russian Far East was examined. Of 55 loci screened, 31 were polymorphic. Within-population variation accounted for most of the allele diversity; FST averaged over loci was 0.052. Linkage disequilibrium was found in less than 5% of locus pairs in the chum population examined. Analysis of within- and among-population variance components of linkage disequilibrium using D-statistics (Ohta, 1982) showed that most genetic variation was distributed among populations.

Animals↗
PubMed1994

[Hormonal interrelationships in symptomatic epilepsy].

The serum and cerebrospinal fluid (CSF) from patients with epilepsy resultant from cerebral leptomeningitis in the fit-free intervals were examined for some hypophyseal and adrenal hormones with reference to the disease course, severity and duration, frequency of the seizures. The levels of hydrocortisone, aldosterone and STH were found stable, while those of prolactin got elevated, especially in males. Hormonal shifts in the serum and CSF appeared significantly different. STH lowered, but prolactin went up only in CSF. The latter increase was related to the seizures frequency.

Adolescent↗
PubMed1983

[Human nutrition in prolonged autonomous crossings over drifting ice].

The authors describe the experience gained with nutrition for participants of ski transitions over drifting ice of the Arctic, organized by the newspaper "Komsomolskaya Pravda" in 1972, 1976 and 1979, including a 76-day transition towards the North Pole. Use was made of dehydrated products with a daily diet mass of 800-3300 g per man, in which fat content was 40-45% of total caloricity, and that of proteins 12-18%. Hot food was taken not less than 2 times a day (breakfast and supper). If the number of transitions exceeds 8-9 a day, it is necessary to have daytime rest and to take hot food. Additional intake of vitamins, particularly of vitamin C, is required, especially during transitions lasting over 20-25 days. If the transitions last over 35-40 days, it is required that additional food and fuel should be supplied. Optimal duration of the intervals between additional food supplies constitutes 12-15 days, the maximal permissible one 25-30 days. It is advisable to have rest days and high-caloric diet every other 15-20 days. The daily energy deficiency amounting to 1250-1500 kcal per man enables the trained group to maintain high physical and intellectual working capacity. However, overall energy deficiency should not exceed 30 000-40 000 kcal per man.

Arctic Regions↗
PubMedDate not supplied

[Nutritional pattern of the "Komsomolskaya Pravda" Arctic expedition].

Data on the chemical composition, nutritional value and caloricity of food ration used by the "Komsomolskaya Pravda" expedition during ski marches in the Arctics are reported. The rations consisted chiefly of dehydrated products and weighed 800-1000 g. The daily caloricity of the rations amounted to 3400 and 4400 great calories.

Arctic Regions↗
PubMedDate not supplied

[State of the metabolism of thiamine in white rats during the long-term administration of ethanol].

Following introduction of ethyl alcohol in a dose of 4 g/kg for 4 months to rats receiving a solid food ration and 5gamma of thiamine the activity of the erythrocytes transketolase and the thiamine level in the liver did not experience any marked changes, but the transketolase activity in the liver increased. A replacement of one half of carbohydrates in the liquid ration with an isocaloric quantity of ethyl alcohol led over a period of 2 and 4 months to a rise in the activity of the erythocytes transketolase. The thiamine content in the liver mounted too, but then transketolase activity in the liver significantly decreased. The cause accounting for the conflicting liver transketolase changes with different rations and the mechanism of the "thiamine-saving" action of ethyl alcohol are discussed.

Alcoholism↗
PubMedDate not supplied

[The rule of "one migrant per generation" and genetic differentiation in subdivided populations].

The genetic differentiation in population with migration according island and two-dimensional stepping stone models was studied with simulation methods. It is shown that migration of one or few individuals per generation is insufficient for leveling differences between subpopulations in allele frequencies. Even if migration is estimated as m = 0.5 (exchange of 50 and 500 individuals per generation) statistically significant differences remain at least in the half of populations with insular structure. Spatial heterogeneity disappears completely only if m = 0.7-0.8. In case of two-dimensional step model the level of genetic differentiation is higher and statistically significant heterogeneity remains at all levels of genetic exchange including that which was estimated as m = 1.

Animal Migration↗