Biochemical and photochemical degradation of the herbicide lontrel

Degradation of Lontrel by activated sludge (AS) of purification works and UV irradiation was studied. 3,6-Dichloropicolinic acid (3,6-DCPA, the main active principle of Lontrel) was not degraded by the microbial association of the AS. AS treated with nitrosourea under various conditions did not oxidize Lontrel either. Hard UV radiation degraded 3,6-DCPA within 4-24 h at constant sparging (bubbling) of air, oxygen, or ozone. The rate of oxidation with oxygen or ozone bubbling was three to four times higher than with air bubbling. It was found that the products of photochemical degradation of Lontrel were also toxic; however, they were readily degraded by AS microorganisms without additional AS treatment.     

Karyological evidence for meiosis in the three different types of life cycles existing in Agaricus bisporus

In Agaricus bisporus all cytological studies performed until now concerned the pseudohomothallic and bisporic var. bisporus. In the past 12 y two tetrasporic varieties have been described, the heterothallic var. burnettii and the homothallic var. eurotetrasporus. Our aim was to compare the behavior of the nuclei in the vegetative and reproductive cells of the three varieties with light microscopy (Feulgen and DAPI staining) and transmission electron microscopy. Most of the vegetative cells contained 3-5 nuclei in the three varieties. Nuclear migrations through the septum were detected. In the basidia relative locations of nuclei and vacuoles, meiotic spindle alignments, relative content of nuclear DNA and synaptonemal complexes were measured or observed. From the observation of numerous asynchronous second division of meiosis within basidia of var. bisporus and var. burnettii a new hypothesis emerges to explain the nonrandom distribution of the four meiotic products in the two spores of the bisporic basidia. Karyogamy and meiosis similarly occurred in the three varieties. In the case of A. bisporus var. eurotetrasporus this implies that the reproductive mode is sexual and therefore homothallic in the strict sense. The three different types of life cycles are described.     

Promoters of genes MTHFR from patients with hyperhomocysteinemia and PTEN from patients with malignant and benign endometrial and ovarian tumors

Mutational changes in the promoter regions of MTHFR genes from patients with hyperhomocysteinemia and PTEN genes from patients with endometrial and ovarian tumors were studied. An increased level of homocysteine was found in a part of the patients with a heterozygous C677T mutation in the MTHFR gene, although a moderate hyperhomocysteinemia is usually associated with homozygous mutation. We hypothesized that, in this case, the allele lacking the C677T mutation may be inactivated by the promoter mutation. The sequencing of both DNA strands of the minimal promoter region of the MTHFR gene in ten patients did not reveal any mutation, which implied another mechanism of the development of hyperhomocysteinemia in these patients. A PCR analysis of the minimal promoter region of the tumor suppressor PTEN in the presence of 2-pyrrolidone in 101 patients from Moscow clinics revealed changes in it in patients with endometrial (56%) or ovarian (29%) cancer, as well as in patients with endometrial hyperplasia and benign ovarian tumors (34 and 29%, respectively). It was presumed that the found modification of PTEN gene promoters may arise from epigenetic alterations (erroneous methylation) or may (more rarely) be induced by mutations. As a result of the studies, new molecular markers associated with endometrial and ovarian tumors were revealed and a simple and effective method of detection of these markers was developed.     

Proton transfer in the photosynthetic reaction center of Blastochloris viridis

Photosynthetic reaction centers of Blastochloris viridis require two quanta of light to catalyse a two-step reduction of their secondary ubiquinone Q(B) to ubiquinol. We employed capacitive potentiometry to follow the voltage changes that were caused by the accompanying transmembrane proton displacements. At pH 7.5 and 20 degrees C, the Q(B)-related voltage generation after the first flash was contributed by a fast, temperature-independent component with a time constant of approximately 30 micros and a slower component of approximately 200 micros with activation energy (E(a)) of 50 kJ/mol. The kinetics after the second flash featured temperature-independent components of 5 micros and 200 micros followed by a component of 600 micros with E(a) approximately 60 kJ/mol.     

Changes in physicochemical properties of proteins, caused by modification with alkylhydroxybenzenes

Kinetic characteristics of model enzymes and physicochemical properties of globular proteins modified by chemical analogues of low-molecular-weight microbial autoregulators (alkylhydroxybenzenes, AHBs) have been studied. C₇ and C₁₂ AHB homologues were used, differing in the length of the alkyl radical and the capacity for weak physicochemical interactions. Both homologues affected the degree of protein swelling, viscosity, and the degree of hydrophobicity. The effects depended on the structure of AHBs, their concentration, and pH of the solution, which likely reflects changes in the charge of the protein globule and its solvate cover. Variations of hydrophobicity indices of AHB-modified enzymes (trypsin and lysozyme) were coupled to changes in the catalytic activity. The values of K _M, measured for the enzymes within both AHB complexes, did not change, whereas V _max increased (in the case of C₇ complexes) or decreased (C₁₂ complexes). Possible molecular mechanisms of changes in the physicochemical and catalytic parameters of enzymatically active proteins, induced by modification with structurally distinct AHBs, are described, with emphasis on targeted regulation of functional activity.     

Synthesis of Anabiosis Autoinducers by Non-Spore-Forming Bacteria as a Mechanism Regulating Their Activity in Soil and Subsoil Sedimentary Rocks

Non-spore-forming bacteria of the genera Arthrobacterand Micrococcus, isolated from permafrost subsoil, were found to produce greater amounts of the d ₁extracellular factor than closely related collection strains isolated from soil. The effect of this factor, responsible for cell transition to anabiosis, was not species-specific. Thus, the d ₁preparation isolated from the culture liquid of the permafrost isolate Arthrobacter globiformis245 produced an effect on the collection strain Arthrobacter globiformisB-1112 and also on Micrococcus luteusand Bacillus cereus.The d ₁preparation from the permafrost isolate of Arthrobacterdiffered from the chemical analogue of this factor, 4-n-hexylresorcinol, in the level of the induced cell response, which may have resulted from different cell sensitivity to various homologs of alkylhydroxybenzenes contained in the d ₁preparation. Thus, additional evidence was obtained indicating that autoregulation of bacterial growth and development is implemented at the level of intercellular interactions in microbial communities. Abundant production of the d ₁anabiosis-inducing factors by bacteria isolated from permafrost subsoil is probably a result of special antistress mechanisms responsible for the survival of these bacteria under extreme conditions of natural long-term cooling.     

Production and specificity of polyclonal antibodies against soluble proteins from the arbuscular mycorrhizal fungus Glomus intraradices

Rabbit polyclonal antibodies were produced against a soluble protein fraction from a vesicle and spore mixture of the arbuscular mycorrhizal fungus (AMF) Glomus intraradices. The protocol for isolation of vesicles and spores from plant roots was optimized to minimize debris contamination. Protein extract purification and preparation for immunization was adapted to increase protein content and immunogenicity. Active antisera were produced starting from the second boost immunization. Antibodies obtained were specific for surface antigens of AMF and revealed different patterns of soluble protein antigens in G. intraradices, G. constrictum and an unidentified Glomus species. Accepted: 6 December 2000     

Results of experimental radiobiological studies made within the 10-kilometer zone of the Chernobyl AES accident]

A study was made of the effect of high radioactive contamination on the animal organism (C57BL/6 mice) and HeLa cell culture within the ten-kilometer zone of the Chernobyl A.P.S. accident. The total radiation dose, as calculated by a gamma-component, was 0.09 to 2 Gy. A long-term exposure of mice within the zone (cumulative dose of 1.8 to 2 Gy) caused a significant decrease in bone marrow stem potencies and changes in the brain vascular system; subsequent acute exposure of animals increased interferon titres in the serum to a much greater extent than a single acute exposure did. As to HeLa cells, irradiation there of with doses of 0.09 to 0.4 Gy during 15-20 postirradiation generations caused a decrease in the proliferative activity, an emergence of cells with micronuclei and of giant cells, and remote cell death.