Is the ubiquinone pool in the respiratory chain of the bacterium Paracoccus denitrificans really unhomogeneous?

We have established the participation of a mobile redox pool in the respiratory chain of anaerobically grown bacterium Paracoccus denitrificans. In testing the kinetical homogeneity of the pool it was found that the ratio of fluxes of electron transport toward the terminal acceptors oxygen and nitrate was coincident for the respiratory substrates NADH and succinate; this provides evidence against the preferential link of one dehydrogenase with a distinct terminal enzyme through the separate pool of ubiquinone. The deviation from the expected behavior observed in comparing the titration of NADH oxidase and succinate oxidase with respiratory inhibitors such as mucidin (inhibitor in the bc₁ region) or cyanide can be accounted for by the activation of succinate dehydrogenase upon the increase in the reduced state of respiratory components during the titration.     

NAD kinase regulates the size of the NADPH pool and insulin secretion in pancreatic β-cells

NADPH is an important component of the antioxidant defense system and a proposed mediator in glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. An increase in the NADPH/NADP(+) ratio has been reported to occur within minutes following the rise in glucose concentration in β-cells. However, 30 min following the increase in glucose, the total NADPH pool also increases through a mechanism not yet characterized. NAD kinase (NADK) catalyzes the de novo formation of NADP(+) by phosphorylation of NAD(+). NAD kinases have been shown to be essential for redox regulation, oxidative stress defense, and survival in bacteria and yeast. However, studies on NADK in eukaryotic cells are scarce, and the function of this enzyme has not been described in β-cells. We employed INS-1 832/13 cells, an insulin-secreting rat β-cell line, and isolated rodent islets to investigate the role of NADK in β-cell metabolic pathways. Adenoviral-mediated overexpression of NADK resulted in a two- to threefold increase in the total NADPH pool and NADPH/NADP(+) ratio, suggesting that NADP(+) formed by the NADK-catalyzed reaction is rapidly reduced to NADPH via cytosolic reductases. This increase in the NADPH pool was accompanied by an increase in GSIS in NADK-overexpressing cells. Furthermore, NADK overexpression protected β-cells against oxidative damage by the redox cycling agent menadione and reversed menadione-mediated inhibition of GSIS. Knockdown of NADK via shRNA exerted the opposite effect on all these parameters. These data suggest that NADK kinase regulates intracellular redox and affects insulin secretion and oxidative defense in the β-cell.     

Does the cellular labile iron pool participate in the oxidation of 2',7'-dichlorodihydrofluorescein?

The fluorogenic probe 2',7'-dichlorodihydrofluorescein diacetate (H₂DCF-DA) is widely used for the estimation of oxidative stress in cells. It is known that 2',7'-dichlorodihydrofluorescein (H₂DCF), product of intracellular hydrolysis of H₂DCF-DA, is oxidized to the fluorescent compound, DCF, mainly by hydrogen peroxide (H₂O₂) in the presence of catalysts. The present study was aimed at answering the question whether the labile iron pool (LIP) may contribute to the oxidation of H₂DCF in cellular systems. The membrane-permeable lipophilic iron chelator salicylaldehyde isonicotinoyl hydrazone (SIH) was found to inhibit oxidation of the probe by H₂O₂ dependent on ferrous ions but not by peroxidase or superoxide dismutase in defined in vitro systems. When applied to cells, the probe inhibited considerably oxidation of H₂DCF in V79 Chinese hamster fibroblasts and two murine lymphoma L5178Y(LY) sublines (LY-R, LY-S) differing in LIP level, the extent of inhibition being greater in the LY-R line of higher LIP level. These results demonstrate that LIP is a significant factor determining the rate of intracellular H₂DCF oxidation.     

Computer simulation of the motoneuron pool–muscle complex. I. Input system and motoneuron pool

 The aim of the present study was to simulate the input system and the motoneuron (MN) pool of the MN pool–muscle complex (MNPMC). Input fibers, which can originate from command centers in the central nervous system or from sensory organs, activate the MN pool. They generate sequences of action potentials, the frequency of which is proportional to a time-dependent activation factor (which is an input to the model). Different connection patterns between the input fibers and motor units (MUs) are allowed. For simplicity and since no precise experimental data are available, 70 input fibers and 4 boutons per fiber and MN are simulated (this corresponds approximately to the monosynaptic group-Ia input of the cat medial gastrocnemius muscle). Each bouton generates the same conductance change in the postsynaptic membrane. The MNs are modeled with a single compartment and a homogenous membrane. According to experimental data, the membrane leakage conductance and capacitance are MU dependent. Since the precise relation is unknown: (a) the computed relation between MU contraction force and the MN leakage conductance was taken from a steady-state MNPMC model, and (b) the capacitance was assumed to be proportional to the leakage conductance. The MN membrane includes time- and voltage-dependent ionic channels (fast and slow K⁺ and low- and high-threshold Ca²⁺ channels). The density and time constant of the slow K⁺ channels and the density of the Ca²⁺ channels were fitted to approximate afterhyperpolarization characteristics and frequency-injected current relations of type-identified cat MNs. If the membrane reaches a voltage threshold the MNs generate action potentials, which were simulated by voltage pulses. The activation of the MN pool of the human first dorsal interosseus muscle was simulated with injected and synaptic currents in order to illustrate the size principle, synaptic noise, and other features of muscle activation. It is concluded that the present model reproduces the main properties of the input–output relations of different MN types within a muscle. Together with the simulation of the muscle force and the surface EMG, which will be published in subsequent papers, it will be a powerful tool for reproducing experiments on the motor system and investigating functional mechanisms of motor control. Received: 17 April 2001 / Accepted in revised form: 6 November 2001     

Acropora recruits harbor “rare” Symbiodinium in the environmental pool

Coral–algal symbioses are essential for the survival of corals. Algal endosymbionts, specifically the dinoflagellate genus Symbiodinium, are divided into several genetic clades. The composition of Symbiodinium within corals plays an important role in the tolerance and/or sensitivity of host corals to local environments, due to individual Symbiodinium-specific physiological characteristics. While the majority of gamete-spawning corals acquire Symbiodinium from the surrounding environment, little is known about whether corals specifically select or randomly acquire Symbiodinium from the environmental population. In the present study, we compared the Symbiodinium clade composition of newly recruited Acropora corals with that of the environmental pool (water column, sediments, and adult colonies). More than 90 % of recruits harbored clades A and/or D until 6 months after settlement, despite the Symbiodinium environmental pool being mainly composed of clade C (mainly ITS1 type C2), and to a lesser extent clades A and D. In addition, the environmentally dominant type C2 Symbiodinium was not detected in Acropora recruits, while a few recruits harbored ITS1 types C1 or C15. Therefore, the clade composition of recruits may not reflect the abundance/density of Symbiodinium populations in the environment. Some members of clades A and D are known to exhibit tolerance to a wide range of environments. ITS1 type C1 also exhibits greater tolerance to thermal stress compared to ITS1 type C2. These tolerance characteristics of certain Symbiodinium may be vital for the initial survival of Acropora recruits, even if these Symbiodinium are rare in the environment.     

The role of growth rate, redox-state of the plastoquinone pool and the trans-thylakoid ΔpH in photoacclimation of Chlorella vulgaris to growth irradiance and temperature

The long-term photoacclimation of Chlorella vulgaris Beijer (UTEX 265) to growth irradiance and growth temperature under ambient CO₂ conditions was examined. While cultures grew at a faster rate at 27 than at 5 °C, growth rates appeared to be independent of irradiance. Decreases in light-harvesting polypeptide accumulation, increases in xanthophyll pool size and changes in the epoxidation state of the xanthophyll cycle pigments were correlated linearly with increases in the relative reduction state of Q_A, the primary quinone receptor of photosystem II, when estimated as 1−q_P under steady-state growth conditions. However, we show that there is also a specific temperature-dependent component, in addition to the redox-state of the Q_A, involved in regulating the content and composition of light-harvesting complex II of C. vulgaris. In contrast, modulation of the epoxidation state of the xanthophyll pool in response to increased 1−q_P in cells grown at 5 °C was indistinguishable from that of cells grown at 27 °C, indicating that light and temperature interact in a similar way to regulate xanthophyll cycle activity in C. vulgaris. Because C. vulgaris exhibited a low-light phenotype in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), but a high-light phenotype upon addition of 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone, we conclude that the plastoquinone pool acts as a sensor regulating the accumulation of light-harvesting polypeptides in C. vulgaris. However, concomitant measurements of non-photochemical fluorescence quenching (q_N) and the epoxidation state of the xanthophyll pool appear to indicate that, in addition to the redox-state of the plastoquinone pool, the trans-thylakoid ΔpH may also contribute to sensing changes in irradiance and temperature that would lead to over-excitation of the photosynthetic apparatus. We suggest that sink capacity as reflected in photosynthate utilization and cell growth ultimately regulate photoacclimation in C. vulgaris. Received: 17 April 2000 / Accepted: 23 May 2000     

Assessment of the role of Ca2+ mobilization from intracellular pool(s), using dantrolene,in the glycogenolytic action of α-adrenergic stimulation in perfused rat liver

To identify the role of Ca²⁺ mobilization from intracellular pool(s) in the action of α-adrenergic agonist, the effects of dantrolene on phenylephrine-induced glycogenolysis were investigated in perfused rat liver. Dantrolene (5·10⁻⁵ M) inhibited both glycogenolysis and ⁴⁵Ca efflux induced by 5·10⁻⁷ M phenylephrine. The inhibition by dantrolene was observed in the presence and absence of perfusate calcium. In contrast, dantrolene did not inhibit glycogenolysis induced by glucagon. To confirm the specificity of dantrolene action on calcium release in liver, experiments were also carried out using isolated hepatocytes. Dantrolene did not affect phenylephrine-induced production of inositol 1,4,5-trisphosphate. The compound did inhibit a rise in cytoplasmic Ca²⁺ concentration induced by phenylephrine both in the presence and absence of extracellular Ca²⁺. Thus, these results suggest that calcium release from an intracellular pool is essential for the initiation of α-adrenergic stimulation of glycogenolysis in the perfused rat liver.     

Is replenishment of the readily releasable pool associated with vesicular movement?

At the excitatory synapse of rat hippocampus the short-term synaptic depression observed during long high-frequency stimulation is associated with slower replenishment of the readily-releasable pool. Given that the replenishment rate is also not [Ca⁺⁺]_o sensitive this puts into question a widely held notion that the vesicles—constrained by the cytoskeleton and rendered free from such constraints by Ca⁺⁺ entry that renders them more mobile—are important in the replenishment of the readily-releasable pool. This raises a question—Is vesicular replenishment of the readily releasable pool associated with significant movement? To answer this question we evaluated how okadaic acid and staurosporine (compounds known to affect vesicular mobility) influence the replenishment rate. We used patterned stimulation on the Schaffer collateral fiber pathway and recorded the excitatory post-synaptic currents (EPSCs) from rat CA1 neurons, in the absence and presence of these drugs. The parameters of a circuit model with two vesicular pools were estimated by minimizing the squared difference between the ESPC amplitudes and simulated model output. [Ca²⁺]_o did not influence the progressive decrease of the replenishment rate during long, high frequency stimulation. Okadaic acid did not significantly affect any parameters of the vesicular storage and release system, including the replenishment rate. Staurosporine reduced the replenishment coupling, but not the replenishment rate, and this is owing to the fact that it also reduces the ability of the readily releasable pool to contain quanta. Moreover, these compounds were ineffective in influencing how the replenishment rate decreases during long, high frequency stimulation. In conclusion at the excitatory synapses of rat hippocampus the replenishment of the readily releasable pool does not appear to be associated with a significant vesicular movement, and during long high frequency stimulation [Ca⁺⁺]_o does not influence the progressive decrease of vesicular replenishment.     

Abundance�Coccupancy relationships in metapopulations: examples of rock pool Daphnia

Intraspecific positive relationships between abundance and occupancy are observed for many species, suggesting that the same processes drive local and regional species dynamics. Two main groups of mechanisms explain this relationship: spatiotemporal variation in local population growth rates due to variation in habitat quality, or dispersal effects that increase occupancy of a species when locally abundant. Several studies show that spatiotemporal variation in population growth rates causes positive abundance?Coccupancy relationships, but few have shown dispersal effects. It is believed that such effects should be more evident for species whose dispersal is limited, e.g. metapopulations, but those studies are limited. This study investigates abundance?Coccupancy relationships in three Daphnia metapopulations in rock pools and the degree to which dispersal or habitat quality affect their local abundances and occurrence. Daphnia longispina and Daphnia magna showed positive abundance?Coccupancy relationships, but not Daphnia pulex. No single ecological factor could explain the abundance?Coccupancy relationships of any given species. Instead, dispersal processes and rock pool quality (mainly salinity and depth) seem to act together to shape the abundance?Coccupancy relationships. Such a conclusion is also supported by an immigration experiment in natural rock pools. This study suggests that although positive abundance?Coccupancy relationships may be commonly found for metapopulations, both dispersal processes and variation in habitat quality can be factors determining the abundance?Coccupancy relationship of metapopulations experiencing habitat heterogeneity.     

Is there a Finno-Ugric component in the gene pool of Russians from Yaroslavl oblast? Evidence from Y-chromosome

The Upper Volga region was an area of contacts of Finno-Ugric, Slavic, and Scandinavian speaking populations in the 8th–10th centuries AD. However, their role in the formation of the contemporary gene pool of the Russian population of the region is largely unknown. To answer this question, we studied four populations of Yaroslavl oblast (N = 132) by a wide panel of STR and SNP markers of the Y-chromosome. Two of the studied populations appear to be genetically similar: the indigenous Russian population of Yaroslavl oblast and population of Katskari are characterized by the same major haplogroup, R-M198 (xM458). Haplogroup R-M458 composes more than half of Sitskari’s gene pool. The major haplogroup in the gene pool of the population of the ancient town of Mologa is N-M178. Subtyping N-M178 by newest “genomeera” Y-SNP markers showed different pathways of entering this haplogroup into the gene pools of Yaroslavl Volga region populations. The majority of Russian populations have subvariant N3a3-CTS10760; the regular sample of Yaroslavl oblast is equally represented by subvariants N3a3-CTS10760 and N3a4-Z1936, while subvariant N3a4-Z1936 predominates in the gene pool of population of Mologa. This N3a4-Z1936 haplogroup is common among the population of the north of Eastern Europe and the Volga-Ural region. The obtained results indicate preservation of the Finno-Ugric component in the gene pool of population of Mologa and a contribution of Slavic colonization in the formation of the gene pool of the Yaroslavl Volga region populations and make it possible to hypothesize the genetic contribution of the “downstream” (Rostov- Suzdal) rather than “upstream” (Novgorod) Slavic migration wave.     

The gene pool of the Belgorod oblast population: Description of the “genetic landscape” of 22 district populations

Data on the frequencies of all (50412) surnames in a total population of 849399 people have been treated by various methods of multivariate statistics (cluster analysis, multidimensional scaling, and factor analysis) to show that 22 district populations of the Central Chernozem region of Russia form a definite, ordered system of population groups. All raions (administrative districts) of Belgorod oblast (administrative region) have been grouped into four clusters corresponding to the actual geographic locations of the populations. Districts of the eastern cluster are characterized by very specific spectrum and frequencies of surnames; districts of the western cluster differ in a high proportion of Ukrainian surnames     

The gene pool of the Belgorod oblast population: II. “Family name portraits” in groups of districts with different degrees of subdivision and the role of migrations in their formation

The frequencies and spectra of surnames have been analyzed in groups of raions (districts) of the Belgorod oblast (region) with different degrees of population subdivision. The “family name portraits” of districts with low (0.00003 < < f*_r < 0.00022, \(\overline {f_r^ * } \) = 0.00015) and moderate (0.00023 < f*_r < 0.00042, \(\overline {f_r^ * } \) = 0.00029) inbreeding levels are similar both to each other and to the “family name portrait” of the Belgorod oblast as a whole. Districts with high subdivision levels (0.00043 < f*_r < 0.00125, \(\overline {f_r^ * } \) = 0.00072) had very distinctive surname spectra and the highest surname frequencies. Intense immigration to the Belgorod oblast significantly affects its population genetic structure, decreasing the population subdivision.     

Effect of parasympathetic denervation on acetylcholine levels in the rat parotid gland. Is there an extraneuronal pool of acetylcholine?

Parasympathetic denervation of the rat parotid gland by avulsion of the auriculotemporal nerve caused a marked and lasting decrease in gland weight. Parasympathectomy did not change the levels of choline in the gland but decreased by 60% the levels of acetylcholine (ACh) ten days after surgery and 65% at 28 days. It is puzzling that relatively high levels of ACh remained after parasympathetic denervation. The presence of additional cholinergic nerves that innervate the gland, or pass through it en route to other structures may account for some of the remaining ACh. Also, Schwann cells from denervated nerves might have contributed to some of the ACh. The existence of an extraneuronal source of ACh is considered.     

Structure and floristic composition of the Heard Island “pool complex” community

Summary The stratigraphy, hydrology and vegetation of the Heard Island (sub-Antarctic; 53°05S, 73°30E) pool complex bogs are described. Spatial variation in processes that might have contributed to their formation are discussed. This community occurs where drainage is impeded. with Callitriche antarctica being the indicator species. Particular attention is paid to the interaction of the vegetation, pools and animals. Surface stratigraphy, peat depth, water depth and vegetation composition were measured along transect lines. Species cover abundance data of 300 quadrats were classified using a two-way indicator species analysis program and ordinated using detrended correspondence analysis. The major factors determining vegetation composition were found to be peat depth, surface topography, and the degree and type of animal disturbance. Similarities between the pool complexes on Heard Island and corresponding bogs in Tasmania, and the northern hemisphere temperate and boreal zones appear to diminish as the density of the animals occupying this habitat increases.     

Estimating the gene pool condition in natural populations of invertebrates in the fragmented landscape of Moscow and Moscow district with special reference to shrub snail Bradybaena fruticum Müll

Using shrub snail Bradybaena fruticum Müll (20 populations) as a model, we were the first in Russia and in the world to develop a system of urban ecological genetic monitoring of the gene pool of an invertebrate species. The results of isozyme polymorphism studies in shrub snail populations showed a dramatic (up to 70%) reduction in genetic diversity in small isolates from the urbanized environment as compared to large natural populations. In urban populations, genetic diversity parameters were demonstrated to be lower than in natural ones: the mean heterozygosity per locus was reduced up to 0.08 (0.15-0.20 in natural populations); the mean allele number, to 1.9 (2.7 in natural populations); and the number of polymorphic loci, to four, i.e., 2.2-fold (nine in natural populations). In Moscow district, the number of polymorphic loci also decreased to five in the population subjected to anthropogenic pressure. The changes in the population gene pool (as shown by the number of polymorphic loci) were different in Moscow and Moscow district. The percentage of populations with the number of polymorphic loci as low as four to six was 76.9 in Moscow and 23.1% in Moscow district. The gene pool quality of 80% of the urban snail populations was estimated as unsatisfactory, and in half of them, as critical. The main reason for these changes seems to be genetic drift accompanied by inbreeding, caused by fragmentation of the range and reduction in the abundance of populations of the species, due to the anthropogenic pressure. The results of the study were employed in the program of the Moscow government for restoring the gene pools of endangered animals species on the preserved territories of the city.     

Does a relationship exist between the urate pool in the body and lipid peroxidation during exercise?

In this study, we investigated whether a relationship exists between the levels of urate in vivo and lipid peroxidation during exercise. Seven healthy male subjects performed exhaustive cycling exercise under the following three conditions. The levels of urate, thiobarbituric acid reactive substances (TBARS) and allantoin in plasma and urine were examined before exercise and during a 3h recovery period. (1) Benzbromarone administration experiment: benzbromarone (an uricosuric agent) was administered orally the day before exercise. (2) IMP administration experiment: inosine 5'-monophosphate disodium salt (a precursor of urate) was administered orally the day before exercise. (3) Control experiment: no test substance was administered. The main results obtained were as follows. Plasma urate levels and total peroxyl radical-trapping antioxidant parameter (TRAP) for deproteinized plasma in the resting period significantly decreased depending on the treatment, in the order of IMP> control > benzbromarone. A significant positive correlation was evident between plasma urate levels and TRAP values for deproteinized plasma. The increase in plasma levels of allantoin was observed only in the case of IMP treatment. A significant negative correlation between plasma levels of urate in the resting period and the amounts of urinary TBARS excreted during the recovery period was recognized. These results suggest that the urate level in vivo before exercise is a factor influencing lipid peroxidation during exhaustive exercise. Furthermore, these findings support the view that urate may serve as an important freeradical scavenger in vivo.     

Heterogeneity of depolymerized heparin SEC fractions: to pool or not to pool?

In the structural analysis of heparin and heparan sulfate, it is customary to combine or pool like-sized fractions obtained by size-exclusion chromatography (SEC) of enzymatically derived heparin oligosaccharides. In this study, we examine the heterogeneity of preparative-scale SEC fractions obtained from enzymatic digests of porcine intestinal mucosa heparin. Each fraction was profiled by capillary electrophoresis with UV detection (CE−UV) using a 60 mM formic acid running buffer at pH 3.43. Differences in the composition and relative concentration of components of the SEC fractions were observed for disaccharides and larger oligosaccharides. The heterogeneity of the fractions becomes more pronounced when heparin is digested using a heparin lyase cocktail. The heterogeneity of preparative SEC fractions was further investigated by reversed-phase ion-pairing ultraperformance liquid chromatography coupled with mass spectrometry (RPIP−UPLC−MS) using the ion-pairing reagent, tributylamine (Bu₃N). Our results suggest that preliminary profiling of preparative SEC fractions prior to pooling may simplify efforts to identify and/or isolate rare structures.     

Do the capacity and kinetics for modification of xanthophyll cycle pool size depend on growth irradiance in temperate trees?

The present study investigated the interaction of growth irradiance (Q_int) with leaf capacity for and kinetics of adjustment of the pool size of xanthophyll cycle carotenoids (sum of violaxanthin, antheraxanthin and zeaxanthin; VAZ) and photosynthetic electron transport rate (J_max) after changes in leaf light environment. Individual leaves of lower‐canopy/lower photosynthetic capacity species Tilia cordata Mill. and upper canopy/higher photosynthetic capacity species Populus tremula L. were either illuminated by additional light of 500–800 µmol m^?2 s^?1 for 12 h photoperiod or enclosed in shade bags. The extra irradiance increased the total amount of light intercepted by two‐fold for the upper and 10–15‐fold for the lower canopy leaves, whereas the shade bags transmitted 45% of incident irradiance. In control leaves, VAZ/area, VAZ/Chl and J_max were positively associated with leaf growth irradiance (Q_int). After 11 d extra illumination, VAZ/Chl increased in all cases due to a strong reduction in foliar chlorophyll, but VAZ/area increased in the upper canopy leaves of both species, and remained constant or decreased in the lower canopy leaves of T. cordata. The slope for VAZ/area changes with cumulative extra irradiance was positively associated with Q_int only in T. cordata, but not in P. tremula. Nevertheless, all leaves of P. tremula increased VAZ/area more than the most responsive leaves of T. cordata. Shading reduced VAZ content only in P. tremula, but not in T. cordata, again demonstrating that P. tremula is a more responsive species. Compatible with the hypothesis of the role of VAZ in photoprotection, the rates of photosynthetic electron transport declined less in P. tremula than in T. cordata after the extra irradiance treatment. However, foliar chlorophyll contents of the exposed leaves declined significantly more in the upper canopy of P. tremula, which is not consistent with the suggestion that the leaves with the highest VAZ content are more resistant to photoinhibition. This study demonstrates that previous leaf light environment may significantly affect the adaptation capacity of foliage to altered light environment, and also that species differences in photosynthetic capacity and acclimation potentials importantly alter this interaction.     

Fragmentation of the Québec population genetic pool (Canada): evidence from the genetic contribution of founders per region in the 17th and 18th centuries

The 6 million French-Canadians of Québec derive from a relatively small number of founders. Consequently, some hereditary diseases, which may or may not present a worldwide distribution, have been detected in high frequency in this population. Several studies, however, indicate a nonuniform distribution of these diseases through the population, suggesting that the French-Canadian founder effect has been geographically stratified. Here we explore this stratification by using a demographic database, the Population Register of Early Québec, that contains almost all birth, marriage, and death certificates (>712,000) recorded in parish registers between 1608-1800. In this database, every genealogical link has been traced back to the founders of the population, so that we can compute the genetic contribution of founder per region, and then account for the early events that have shaped the distribution of diseases. Ten regions, comprising varying numbers of parishes, have been selected. We first describe each region in terms of homogeneity and concentration of its gene pool. For this purpose, a new concept is introduced, the founders' uniform contribution number (FUN), i.e., the number of founders a population would have if all its founders had an equal contribution. Second, we estimate genetic similarity between regions on the basis of differential genetic contribution. To classify the regions, we use principal component and cluster analysis. Our results show a tripartite clustering of the population, and invite us to reconsider the results obtained from biomolecular and clinical studies, which show a bipartite clustering.     

The gene pool of the Belgorod oblast population: Malecot’s isolation-by-distance parameters

The mean distance between birthplaces of spouses (σ, σ′), the proportion of medium migrations (k), and the effective migration pressure (M _e) have considerably increased, and the linear systematic pressure coefficient (b) has decreased in the human population of the Central Chernozem region during the past 50 years. However, the local inbreeding level (a), which is determined by both an increase in the migration intensity and a decrease in the effective population size (N _e), has remained practically unchanged. A change in the regional administrative structure has affected the genetic structure of populations. In the 1950s, raions (administrative districts) of Kursk and Voronezh oblasts (regions) were similar with respect differentiation parameters, whereas the oblasts considerably differed from each other. At present, some Malecot’s isolation-by-distance parameters for the populations of the districts that were included to Belgorod oblast in 1954 are lower and similar to those for the districts that remain in Kursk and Voronezh oblasts.