Reduction of Selenite by Azospirillum brasilense with the Formation of Selenium Nanoparticles

The ability to reduce selenite (SeO₃ ^2?) ions with the formation of selenium nanoparticles was demonstrated in Azospirillum brasilense for the first time. The influence of selenite ions on the growth of A. brasilense Sp7 and Sp245, two widely studied wild-type strains, was investigated. Growth of cultures on both liquid and solid (2 % agar) media in the presence of SeO₃ ^2? was found to be accompanied by the appearance of the typical red colouration. By means of transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and X-ray fluorescence analysis (XFA), intracellular accumulation of elementary selenium in the form of nanoparticles (50 to 400 nm in diameter) was demonstrated for both strains. The proposed mechanism of selenite-to-selenium (0) reduction could involve SeO₃ ^2? in the denitrification process, which has been well studied in azospirilla, rather than a selenite detoxification strategy. The results obtained point to the possibility of using Azospirillum strains as endophytic or rhizospheric bacteria to assist phytoremediation of, and cereal cultivation on, selenium-contaminated soils. The ability of A. brasilense to synthesise selenium nanoparticles may be of interest to nanobiotechnology for “green synthesis” of bioavailable amorphous red selenium nanostructures.     

Interaction of the haloalkaliphilic purple bacteria <Emphasis Type="Italic">Rhodovulum steppense</Emphasis> with aluminosilicate minerals

The interaction was investigated between the haloalkaliphilic nonsulfur purple bacteria Rhodovulum steppense A-20s^T and layered aluminosilicates: micas (biotite, phlogopite, and muscovite) and clay minerals (montmorillonite and kaolinite). The interaction between all components of this system (minerals, water, medium, and bacteria) resulted in the changes in the chemical composition of the minerals and solutions. These changes were especially significant in the presence of bacteria. By using some elements for growth and promoting their transfer into the exchange pool of the minerals, bacteria removed these elements from the medium. The content of exchange bases in the aluminosilicates incubated in the presence of bacteria was several times higher than in the minerals incubated in sterile medium. The observed saturation of the mineral phase with potassium and magnesium may be considered the initial phase of diagenesis of the aluminosilicates under study.     

Risk of genetic transformation of multipotent mesenchymal stromal cells in vitro

Proof of the efficacy of cell therapy by numerous studies and clinical trials inevitably has raised the question of improving the regulatory framework that governs its use. Particular attention should be paid to the genetic safety of cell preparations. The immune, genetic, and pharmacological modification and expansion of cells in vitro can lead to an undesired effect, which not only has reduced the healing, recovery, and regulatory potential of cell therapy, but also increased the risk of accumulating genetically aberrant cells and the oncogenic transformation of cell preparations. The article has presented the estimation of the parameters of the genetic stability of cultured multipotent mesenchymal stromal cells (MSCs) derived from bone marrow and adipose tissue. The study was conducted using classic methods of genotoxicology, i.e., the individual cells gel-electrophoresis (comet assay) and the micronucleus test. We described a basic level of DNA damage and the frequency of micronucleus, identified genetically instable cultures, and conducted the comparison of genetic variability of MSCs isolated from different tissues.     

Comparative assessment of inductive effects of Azospirillum lectins with different antigenic properties on the signal systems of wheat seedling roots

The lectins of associative nitrogen-fixing bacteria Azospirillum brasilense Sp7 and its mutant A. brasilense Sp7.2.3 were shown to have different effects on the components of the wheat seedling root signal system, namely to regulate the levels of cAMP, nitric oxide, diacylglycerol, and salicylic acid, as well as to induce the activities of superoxide dismutase and lipoxygenase. Our results make it possible to consider azospirilla lectins as inducers of the signal systems in wheat seedling roots, since they cause development of several flows of primary signals. These data are of general biological importance, since lectins are present in all living organisms and most of the functions of lectins remain insufficiently understood.     

About possible functional interaction between serotonin and neuropeptides in control processes of embryogenesis (Experiments on embryos ofTritonia diomedea)

Ritanserin and inmecarb hydrochloride, antagonists of serotonin, act cytostatically and teratogenically on early embryos ofTritonia diomedea, a nudibranch mollusk. On the basis of a pharmacological analysis and the type of developmental abnormalities observed, this action appears to be due to disturbances in the functional activity of endogenous serotonin and is associated with damage to the cytoskeleton. The effects of ritanserin and inmecarb are prevented or attenuated by lipophilic serotonin analogs (serotoninamides of polyenoic fatty acids), as well as by polypeptides isolated from neurons Pd5 and Pd6 of the pedal ganglia of the adultTritonia. In late embryos (stage of veligers), serotonin and to a lesser extent its lipophilic analogs strongly increase embryonic motility. This effect of serotonin is potentiated by some neuropeptides and inhibited by others. These results provide evidence for functional interaction between serotonin and neuropeptides in the control processes of embryogenesis.     

Relation of the progestagenic activity and conformation of the 17beta-acetyl side chain in the D'6-pentarane series

The synthesis of 2' beta-methyl-16 alpha,17 alpha-cyclohexanoprogesterone and its MM2 conformational analysis have been performed. The acetyl side chain was shown to have an unusual conformation with the torsion angle C13-C17-C20-O20 being -32.1 degrees. This conformation is by 5.4 kJ.mol-1 more stable than the usual one with the torsion angle 130.3 degrees. 2' beta-Methyl-16 alpha,17 alpha-cyclohexanoprogesterone proved to be inactive as a progestogen (pregnancy maintenance and McPhail tests). The lack of the activity may be due to the additional methyl group in D'-ring causing a change of the conformation of the 17 beta-acetyl side chain, thus hindering the formation of the conformation necessary for binding to the progesterone receptor.     

immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma

The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA.     

Analysis of ERK1/2 kinases in the inferior colliculus of rats genetically prone to audiogenic seizures during postnatal development

The activity of ERK1/2 kinases in the quadrigemina inferior colliculus of Krushinsky–Molodkina rats of different age, which are characterized by an increased seizure readiness compared to Wistar rats, was analyzed. An increased (probably genetically determined) activity of these enzymes during the development of epileptiform activity in ontogeny was found, which may be the cause of abnormalities in the neurotransmitter system functioning.     

Genetic architecture of survival and fitness-related traits in two populations of Atlantic salmon

The additive genetic effects of traits can be used to predict evolutionary trajectories, such as responses to selection. Non-additive genetic and maternal environmental effects can also change evolutionary trajectories and influence phenotypes, but these effects have received less attention by researchers. We partitioned the phenotypic variance of survival and fitness-related traits into additive genetic, non-additive genetic and maternal environmental effects using a full-factorial breeding design within two allopatric populations of Atlantic salmon (Salmo salar). Maternal environmental effects were large at early life stages, but decreased during development, with non-additive genetic effects being most significant at later juvenile stages (alevin and fry). Non-additive genetic effects were also, on average, larger than additive genetic effects. The populations, generally, did not differ in the trait values or inferred genetic architecture of the traits. Any differences between the populations for trait values could be explained by maternal environmental effects. We discuss whether the similarities in architectures of these populations is the result of natural selection across a common juvenile environment.