Aconitate hydratase of mammals under oxidative stress

Data on the structure, functions, regulation of activity, and expression of cytosolic and mitochondrial aconitate hydratase isoenzymes of mammals are reviewed. The role of aconitate hydratase and structurally similar iron-regulatory protein in maintenance of homeostasis of cell iron is described. Information on modifications of the aconitate hydratase molecule and changes in expression under oxidative stress is generalized. The role of aconitate hydratase in the pathogenesis of some diseases is considered.     

Quantitative criteria for the estimation of the effectiveness of bioluminescence expression in natural and transgenic luminescent bacteria

Computation coefficients for estimating the effectiveness of bioluminescence expression in natural luminescent bacteria P. leiognathi 54 and transgenic strain E. coli Z905/pPHL7 bearing lux-operon in multicopy plasmid are suggested, and their use on the molecular, cell, and population levels was considered. It was shown that, on the population level, all transgenic variants got the better of natural variants of P. leiognathi 54 irrespective of the type of lux-operon regulation. On the cell level, in the bright and dim variants of the transgenic strain, the effectiveness of bioluminescence expression increases by several orders. On the level of one lux-operon, the effectiveness of expression of the bright variant of transgenic strain is substantially higher than in the natural bright variant; in dim variants, the efficiency values are similar, and the effectiveness of bioluminescence expression in the dark variant of E. coli Z905-2 /pPHL7 is by two orders lower than that in the dark variant of P. leiognathi 54.     

Effects of various hyperbaric gas mixtures on hormonal parameters of healthy human blood and saliva

Changes in some hormonal parameters of healthy subjects were studied during experimental 3- to 18-day dives in hyperoxic (oxygen-nitrogen-helium) and argon-containing (normoxic and hyperoxic) gas mixtures. The blood levels of growth hormone, corticotropin, thyrotropin (TSH), thyroid hormones, total cortisol, insulin, and C-peptide, as well as the total salivary free cortisol, were measured during and after hyperbaric exposure. In most cases, the changes in these parameters did not exceed normal clinical and individual ranges. A statistically significant increase in the total cortisol and blood TSH were detected during the exposure to hypoxic oxygen-nitrogen and oxygen-nitrogen-argon mixtures. The time course of salivary free cortisol indicated the most stressful periods of the experimental exposures.     

The effects of copper and zinc on <Emphasis Type="Italic">Spirulina platensis</Emphasis> growth and heavy metal accumulation in its cells

The effects of copper and zinc on Spirulina platensis (Nordst.) Geitl. growth and the capability of this cyanobacterium for accumulation of these heavy metals (HMs) were studied. S. platensis tolerance to HMs was shown to depend on the culture growth phase. When copper was added during the lag phase, its lethal concentration was 5 mg/l, whereas 4 mg/l were lethal during the linear growth phase. Zinc concentration of 8.8 mg/l was lethal during the linear but not lag phase of growth. HM-treated S. platensis cells were capable for accumulation of tenfold more copper and zinc than control cells. Independently of Cu²⁺ content in the medium and of the growth phase, cell cultures accumulated the highest amount of this metal as soon as after 1 h, which may be partially determined by its primary sorption by cell-wall polysaccharides. A subsequent substantial decrease in the intracellular copper content occurred due to it secretion, which was evident from the increased metal concentration in the culturing medium. When zinc was added during the linear growth phase, similar pattern of its accumulation was observed: the highest content after 1 h and its subsequent decrease to the initial level. When the initial density of the culture was low and the cells had much time to adapt to HM, zinc accumulated during the entire linear growth phase, and thereafter the metal was secreted to the medium. The mechanisms of S. platensis tolerance to HM related to both their sorption by the cell walls and secretion of metal excess into the culturing medium and its conversion into the form inaccessible for the cells are discussed.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 259–265.Original Russian Text Copyright © 2005 by Nalimova, Popova, Tsoglin, Pronina.This revised version was published online in April 2005 with a corrected cover date.     

East European lowland as an area of long-time interaction between Caucasoid and Mongoloid peoples

Most of the population of Eastern Europe inhabit an area of great anthropological interest, because of the contact between Caucasoid and Mongoloid anthropological types. We have analyzed normal variability in minisatellite and microsatellite loci in some East European population. Different synthetic maps were constructed using reliability theory to evaluate the degree of accuracy. Comparison of the synthetic maps for DNA with classical markers has revealed a high level of correlation. All the data obtained show the diverse influence of both anthropological types in forming the gene pool of the Eastern European peoples.     

Distribution of Heterotrophic Bacteria in Lake Shira

A study of the horizontal and vertical distribution of heterotrophic bacteria in brackish Lake Shira in summer periods showed that mesophilic bacteria dominated in all areas of the lake, whereas psychrotolerant bacteria dominated in the metalimnion and hypolimnion of its central part. Nonhalophilic bacteria were mostly mesophilic and dominated in coastal waters. Most psychrotolerant bacteria were able to grow in the presence of 5–10% NaCl. Heterotrophic bacteria isolated in different regions of the lake were identified to a generic level. The isolates were classified into autochthonous and allochthonous microorganisms on the bases of their distribution pattern in the lake water, halotolerance, and ability to grow at low temperatures.     

Stability of Recombinant Plasmids in Transgenic Microorganisms under Different Environmental Conditions

The copy number of R plasmids weakly depends on the selective pressure of the respective antibiotic but does depend on the physiology of the host species and the type of plasmids and cloned genes, whose expression leads to a further load on the biosynthetic apparatus of cells. The last factor is critical in the maintenance of recombinant plasmids in transgenic microorganisms.     

Coexistence of Genetically Engineered Escherichia coliStrains and Natural Microorganisms in Experimental Aquatic Microcosms

In experimental aquatic microcosms (AMCs), the population of the Escherichia colistrain Z905 harboring the recombinant plasmid pPHL7 (Ap^rLux⁺) was found to gradually accumulate AMC-adapted cells, which retained the plasmid but differed from the original cells in some biochemical and physiological characteristics. Both the original and the AMC-adaptedE. colicells could coexist with the native AMC microflora for one year or longer. When introduced into AMCs together with native pseudomonads, the AMC-adapted E. coliZ905-33 (pPHL7) cells were more competitive than the nonadapted cells.     

In vitro Development of Murine Embryos Using Different Types of Microinjections

We studied the effects of different types of microinjections, such as the mechanical damage to cytoplasmic and nuclear membranes of the zygote and the injection of various gene-engineering constructs or buffer solutions into the cytoplasm or the pronucleus, on the preimplantation of murine embryos (CBA × C57BL)F₁. The survival rate of the embryos was estimated by their capacity to develop in vitro to the blastocyst or hatched blastocyst stages. Puncture of the cytoplasm using a microneedle and injection of buff or foreign DNA did not affect the zygotes capacity for further in vitro development. But, the puncture of the pronucleus and microinjection of gene-engineering constructs or buffer into it reliably decreased the survival rate of embryos, as compared to the control. The differences were found in the capacity of murine zygotes for in vitro development after injection with gene-engineering constructs.     

Ion Specificity of Na+-Transporting Systems in the Plasma Membrane of the Halotolerant Alga Tetraselmis (Platymonas) viridis

Vesicular preparations of plasma membranes (PM) from the microalga Tetraselmis (Platymonas) viridisRouch were used to investigate the ion specificity of the Na⁺/H⁺antiporter and Na⁺-translocating ATPase, two Na⁺-transporting systems previously identified functionally by our studies of T. viridisPM. The Na⁺/H⁺antiporter and Na⁺-ATPase were shown to translocate, with similar efficiencies, Na⁺and Li⁺across the membrane, whereas other cations, such as K⁺, Rb⁺, and Cs⁺, were not transported by these systems. Transport of the latter cations across PM of T. viridisoccurred through the ion channels of PM, which were apparently selective for K⁺.