The taxonomic significance of the trunk limbs of the chydoridae (Cladocera)

Summary The differences in the structure of the trunk limbs allow to outline three sections of Chydoridae (see table I and fig. 1), coinciding with the sections distinguished according to the structure of the head pores.

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Chydoridae (Cladocera)

Chydoridae (. ), , .

     

Effect of Low-Frequency Pulsed Magnetic Field and Low-Level Laser Radiation on Oxidoreductase Activity and Growth of Fungi—Active Destructors of Polymer Materials

Microbiology - Effect of low-frequency pulsed magnetic field and of low-intensity laser radiation on mycelial fungi actively degrading various polymer materials was studied. These factors had a...     

Sea Cucumbers Triterpene Glycosides, the Recent Progress in Structural Elucidation and Chemotaxonomy

Triterpene glycosides are characteristic metabolites of sea cucumbers (Holothurioidea, Echinodermata). Majority of the glycosides belong to holostane type (lanostane derivatives with 18(20)-lactone). Carbohydrate chains of these glycosides contain xylose, glucose, quinovose, 3-O-methylglucose and 3-O-methyl sylose. During the last 5 years, main investigations were focused on holothurians belonging to the order Dendrochirotida collected in the North Pacific, North Atlantic, Antarctic and in subtropical waters. The glycosides of holothurians belonging to the order Aspidochirotida have also been studied. The most uncommon structural features of carbohydrate chains of new glycosides were: (1) the presence of quinovose as fifth terminal monosaccharide unit and the presence of two quinovose residues; (2) the presence of glucose instead of common xylose as fifth terminal monosaccharide unit; (3) trisaccharide carbohydrate chain; (4) the presence of two 3-O-methylxylose terminal monosaccharide units; (5) the presence of sulfate group at C-3 of quinovose residue. New glycosides without lactone or with 18(16)-lactone and having shortened side chains have also been isolated. The presence of 17α and 12α-hydroxyls, which are characteristic for glycosides from holothurians belonging to the family Holothuriidae (Aspidochirotida) in glycosides of dendrochirotids confirms parallel and relatively independent character of evolution of glycosides. All three families belonging to the order Aspidochirotida: Holothuriidae, Stichopodidae and Synallactidae have similar and parallel trends in evolution of the glycosides carbohydrate chains, namely from non-sulfated hexaosides to sulfated tetraosides. Sets of aglycones in glycosides from holothurians belonging to the genus Cucumaria (Cucumariidae, Dendrochirotida) are specific for each species. The carbohydrate chains are similar in all representatives of the genus Cucumaria.     

Libraries of Large-Insert Genomic Clones as a Tool for Molecular Cytogenetic Analysis of Avian Genome

Integration of molecular and cytegenetic levels of investigation results in complex understanding of structural and functional genome organization. Gridded libraries of large-insert genomic clones represent a powerful tool of the genome analysis. Their utilization provides coordination of data on molecular organization of nucleic acids with cytogenetic data on the chromosome structure. These libraries played an important role in sequencing of genomes of human, mouse, and other organisms as an instrument linking molecular biological and cytogenetic data via construction of contigs and their localization on the chromosomes. They also enabled analysis of orthology between the mammalian genomes. The existing avian libraries fit molecular cytogenetic analysis of the class Aves genome, and can be successfully used for the isolation and characterization of large genomic fragments. This provides utilization of these libraries not only for the chromosome mapping, but also for positional cloning and search for candidate genes for quantitative traits.__________Translated from Genetika, Vol. 41, No. 5, 2005, pp. 581–589.Original Russian Text Copyright © 2005 by Sazanov, Romanov, Smirnov.     

Production of microgram quantities of einsteinium-253 by the reactor irradiation of californium

Einsteinium-253 was obtained by irradiation of 100–200 μg of californium-252 by the flux of thermal neutrons 2-5 X 10¹⁴ neutrons cm^?2 s^?1 during 500–900 h. For the separation of einsteinium from californium and neodimium, which was used as a carrier, the chromatographic method of separation on the Aminex Q-15S resin with particles of 20 to 25 μm was applied.Einsteinium was eluated by a solution of α-oxyisobutirate of ammonium (0.14 M) with pH = 4.95 at room temperature. The coefficient of separation of einsteinium and californium under these conditions is equal to 1.62. The coefficient of purification of einsteinium from californium is ca. 10⁵.     

Studies of the Stability of Microbial Association Use in Industrial Biofiltering of Gaseous Discharges

Results of industrial exploitation of a biofiltration plant tailored for purifying gaseous discharges of hazardous organic components such as toluene, cyclohexane, and xylene, are examined. Both numerical and compositional variations were monitored for a long-term (more than 1.5 years) utilization process in an association of microorganisms decomposing organic pollutants. A population of microbial association composed by one yeast and two bacterial strains in the biofilm on the surface of filtering sheets was abundant (10⁸–10⁹ yeast cells/cm² and 10¹⁰–10¹¹ bacterial cells/cm²) and stable during the whole period of monitoring. A microbial association in the culture medium averaging 10⁶ yeast cells/l and 10⁸ bacterial cells/l is more susceptible to technogenic impacts and seasonal fluctuations. Overall, the biofilter as an open and autonomic system maintained its microbial association, thereby providing high-degree (93–98%) purification of industrial gaseous discharges from organic pollutants.     

Genetic Analysis of Mutation sy2 which Causes Nonhomologous Meiotic Synapsis in Chromosomes of Diploid Rye Secale cereale L.

Partially nonhomologous (heterologous) synapsis of meiotic chromosomes in a spontaneous desynaptic mutant form of rye is determined by two recessive genes, sy2a and sy2b, that have independent expression and inheritance. The third gene, dominant inhibitor suppressing the mutant phenotype, has been revealed in hybrid combinations between sy2 mutants and lines segregating other meiotic mutants: sy10 (heterologous synapsis), sy1, and sy9(asynapsis). All three genes determining desynapsis (sy2a, sy2b, and I) were shown to be nonallelic to monogenic mutations sy10, sy1, and sy9, inherited independently of them and expressed at later stages of prophase I than the sy10 gene. The possibility of modifying monogenic segregation of mutation sy2 by gametophyte selection for a locus linked to the gene expressed as sy2 at particular frequencies of recombination between this gene and selected locus is discussed.