[Specific Features of Microsatellite Polymorphism in Two Species of Arabidopsis].

The results of an analysis of microsatellite polymorphism in two closely related Arabidopsis species that differing by their crossing types are presented. Considerable genetic diversity was revealed in Arabidopsis thaliana populations located at the northern periphery of the species range (Karelia), which was not typical of self-pollinating species. Populations from the northern boundary of the species range in the basin of Lake Onega were found to be more polymorphic (P99% = 0.43; Hexp = 0.17) as compared to populations of the islands of Lake Ladoga, which are located approximately 300 km to the south (P99% = 0.39; Hexp = 0.15). It is suggested that the high population polymorphism of A. thaliana in the northern part of its range is most likely associated with hostile growing conditions and is the basis for the adaptation processes. A. thaliana populations are highly differentiated (G(ST) = 0.783), which is typical of inbred species. However, such a high interpopulation differentiation is probably due to the low level of gene flow. Specifically, five populations out of seven examined are located on the islands, i.e., are to some extent isolated. These great differences between A. thaliana populations in terms of polymorphism, as well as the high haplotype diversity, suggests postglacial colonization of the Karelian territory by many different ancestral forms. The participation of unique alleles of microsatellite loci with many dinucleotide repeats in the adaptive evolution of A. thaliana is discussed. A species population that is rare for Karelia, Arabidopsis lyrata ssp. petraea, is in complete isolation and, due to specific features of the microevolutionary processes in such populations, is characterized by the polymorphism level, which is low for outbred species (P99% = 0.64; Hexp = 0.16). Nevertheless, this population exists in Karelia for a long period of time, pointing to its successful adaptation to these conditions.

[Genetic base of Arabidopsis thaliana (L.) Heynh: fitness of plants for extreme conditions in northern margins of species range].

Flowering time and vernalization requirement were studied in eight natural Karelian populations (KPs) of Arabidopsis thaliana. These KPs consisted of late-flowering plants with elevated expression of flowering repressor FLC and a reduced expression level of flowering activator SOC1 compared to the early-flowering ecotypes Dijon-M and Cvi-0. Despite variations in flowering time and the vernalization requirement among the KPs, two-week-old seedlings showed no changes in either the nucleotide sequence of the FRI gene or the relative expression levels of FRI and its target gene FLC that would be responsible for this variation. An analysis of abscisic acid (ABA) biosynthesis and catabolism genes (NCED3 and CYP707A2) did not show significant differences between late-flowering KPs and the early-flowering ecotypes Dijon-M and Cvi-0. Cold treatment (4 degrees C for 24 h) induced the expression of not only NCED3, but also RD29B, a gene involved in the ABA-dependent cold-response pathway. The relative levels of cold activation of these genes were nearly equal in all genotypes under study. Thus, the ABA-dependent cold response pathway does not depend on FLC expression. The lack of significant differences between northern populations, as well as the ecotypes Dijon-M (Europe) and Cvi-0 (Cape Verde Islands), indicates that this pathway is not crucial for fitness to the northern environment.

[Comparative analysis of genetic structure in natural populations of two Arabidopsis species with different degree of panmixia].

Comparative analysis of genetic structure of northern natural populations of two Arabidopsis species with different degrees of panmixia was performed. The variability of 121 RAPD loci in seven populations of model plant A. thaliana possessing high degree of self fertility was studied together with 93 RAPD loci in population of cross-pollinating species A. lyrata ssp. petraea. The population of A. l. petraea demonstrated higher level of genetic variability (P 99% = 62.50%; H(exp) = 0.169) than the populations of A. Thaliana, which is obviously connected with biological features of reproduction of the species. A significant level of genetic variability (P 99% = 42.27%; H(exp) = 0.126) was revealed in populations of A. thaliana, which is not typical for self-pollinating plant species. The high population polymorphism of A. thaliana in the northern part of its range may be connected with adverse environmental conditions. The genetic distances between populations of the species studied (average DN = 0.494) confirm close relatedness between A. thaliana and A. l. petraea.

[Genetic diversity of insular natural populations of Festuca pratensis Huds.: RAPD analysis].

In natural populations of Festuca pratensis Huds. from the islands of Onega Lake, the level of genetic diversity was evaluated. In three populations variability of 64 RAPD loci was tested. The level of genetic diversity (P95% = 30.2; Hexp = 0.093) was low for a cross-pollinating plant species. Furthermore, genetic similarity between the plants from insular populations was found to be high (IN = 0.887). It was demonstrated that genetic variation among the population accounted for at most 5.3% of total genetic diversity, which, however, was higher than the FST values for continental populations (FST = 0.022). It was suggested that specific features of the genetic structure of insular population, i.e., low gene diversity within the populations along with high differentiation among the populations, were caused by the gene flow attenuation, as a result of isolation, and intensification of inbreeding. These features had negative effect on total population adaptation.

[Diversity of Arabidobsis thaliana (L.) Heynh. natural populations at the northern limits of the species range: RAPD analysis].

In natural populations of Arabidobsis thaliana (L.) Heynh., occupying northern limits of the species range (Karelia), the level of genetic diversity was evaluated. In two insular and one mainland population variability at 82 RAPD loci was tested. Considerable genetic diversity revealed (P = 4.5%; Hexp = 0.177) was not typical of self-pollinating plant species. It was demonstrated that genetic differentiation among the populations (G(ST)= 0.680) was rather high, pointing to the low level of gene flow in the isolated insular populations. It was suggested that the high level of Arabidopsis population polymorphism in Karelia could be associated with extreme growing conditions at the northern limits of the species range.

[Magnetically-guided anesthetics based on highly dispersed iron powders coated by polyacrylamide]. / Magnitoupravliaemye anestetiki na osnove vysokodispersnykh poroshkov zheleza s poliakrilamidnym pokrytiem.

The effect of external magnetic field (direct and alternating) on the targeted delivery and distribution in body tissues of experimental animals of anesthetics (novocain, lidocaine, and trimecaine) immobilized on highly dispersed ferromagnetics with biocompatible coating was studied by the method of emission spectral analysis. The results are compared with the results obtained earlier on highly dispersed iron powders with dextran coating. The parameters for the powders with dextran coating are considerably lower than those for the magnetic carriers with the polyacrylamide coating.

[Genetic diversity of natural populations of Arabidopsis thaliana (L.) Heynh. in Karelia]. / Geneticheskoe razoobrazie prirodnykh populiatsii arabidopsis thaliana (L.) Heynh. v Karelii.

The genetic structure of ten natural populations of Arabidopsis thaliana (L.) Heynh. at eight isozyme loci was studied. The populations were located in the northern part of the species range, 200 km from the north to the south along the Onega Lake coast in Karelia. Considerable genetic diversity (P99% = 43.7, Hobs = 0.003) was revealed that is not typical of populations of self-pollinating plant species. A direct correlation between the proportion of polymorphic loci and geographical latitude was shown (r = 0.68; P < 0.05). It is suggested that a high polymorphism level in Karelian Arabidopsis thaliana (L.) populations increasing from the south to the north is due to extreme environmental conditions in the northern part of the species range. The distribution of genetic diversity within and between populations is typical of self-pollinating species: the larger part of the total diversity resides among populations (GST = 0.583).

[Distribution of anesthetics immobilized on finely dispersed iron powders in the organism of experimental animals]. / Raspredelenie immobilizovannykh na vysokodispersnykh poroshkakh zhelezaanestetikov v organizme eksperimental'nykh zhivotnykh.

Directed delivery and distribution of anaesthetics (novocaine, lidocaine, trimecaine) immobilized on finely dispersed iron powders under the influence of an external magnetic field in body tissues of test animals have been studied. The data of emission spectral analysis relating to concentration of iron in soft and bone tissues of animals influenced by constant and alternating magnetic field on front and reverse sides over a period from 0 to 180 min are given.

Genetic consequences of radioactive contamination for populations of Arabidopsis.

Populations of Arabidopsis thaliana (L.) Heynh. growing within a 30 km radius of Chernobyl and characterized by radioactive contamination levels ranging from 0.02 to 240 mR h-1 were analyzed for the frequency of embryonic lethal mutations in 1987 and 1988. Plots that retained high levels of radioactive contamination long after the initial exposure were characterized by a high frequency of mutant plants. Plots with low levels of radioactive contamination, which were significantly reduced soon after exposure, were characterized by a decrease in the initially high proportion of mutant plants. Populations of Arabidopsis exposed to insignificant radioactive contamination showed no increase in the frequency of mutant plants; mutation levels were comparable to those found in control plants.