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Background. Development of early-ripening spring bread wheat (Triticum aestivum L.) cultivars is an important task for Russian breeders. Knowledge of the genetics of ultraearly varieties – sources of valuable genes that determine an earlier-maturing type of plant development –will be used to work out methods for obtaining source material for breeding.Materials and methods. The ultra-early lines Rico (k65588, var. erythrospermum Koern.) and Rimax (k-67257, var. lutescens (Alef.) Mansf.), and cvs. ‘Max’ (k-57181, var. lutescens) and ‘Leningradskaya 6’ (k-64900, var. lutescens) were studied. Alleles of the Vrn and Ppd genes were identified by PCR according to known publications, and genomic DNA was isolated from 3-day-old seedlings by the CTAB method.Results. In the environments of Northwest Russia, the Rimax and Rico lines are characterized by the highest rate of development before heading among the spring wheat accessions from the VIR collection. In the Rimax and Rico genotypes, the Vrn-A1, Vrn-B1, Vrn-D1 and Ppd-D1 genes were found. Genotypes with different alleles of Ppd-D1 and Vrn-B1 were identified in the Rimax line. Under conditions of a long day (18 hours), in the population of F2 (F3 ) Rico × Rimax hybrids, the ratio of phenotypes with a high development rate to all others was observed as 1 : 15 (χ2 1: 15 = 0.64). Under a short day (12 hours), 5 clearly tested groups were identified in F2 with the ratio 1 : 4 : 6 : 4 : 1 (χ2 = 3.03; χ2 0.05 = 9.48), which indicates the manifestation of cumulative polymerization.Conclusion. Each of the Rimax and Rico lines has two pairs of independent duplicated genes that determine a high development rate. Under short-day conditions, these genes can interact like cumulative polymers. The Rimax and Rico lines, due to their high development rate, are valuable source material to be used in breeding for earliness.

Introduction. The study of the effects of air smoke during natural fires on the reproductive system is the actual scientific problem at present. Material and methods. The experimental study took place in 2 stages. At the first stage of the study, white male rats were exposed to the smoke-bearing effects of wildfire for 7 days (4 hours a day), and at the second stage, 5 days a week (4 hours a day) for one month. Immediately after the end of the exposure, the animals were decapitated under light ether anesthesia to study the morphofunctional state of the reproductive system, which included counting the total number of spermatogonia, the number of tubules with desquamated epithelium, as well as determining the spermatogenesis index and the number of Leydig cells. Results. The functional state of the reproductive system of male white rats after exposure to smoke for 1 week did not have statistically significant differences from the animals of the control group. At the same time, an increment in the duration of exposure (4 weeks) led to significant morphological and functional disorders of the reproductive system of male white rats, characterized by a decrease in the spermatogenesis index with a simultaneous decrease in the percentage of spermatogonia and the number of interstitial Leydig cells. Discussion. Male reproductive health can be a sensitive marker of environmental factors, and there is no evidence of smoke from natural fires in modern literature. This study justifies the need to develop new approaches to the diagnosis and prevention of adverse effects on the body for a long stay in a smoke area. Conclusion. The results of the study indicate the prolonged exposure to combustion products released during a forest fire to lead to inhibition of reproductive function in male white rats.

The morphological and physiological characteristics of Bacillus thuringiensis strains were analyzed and conditions for obtaining culture fluid with maximum yield of secreted RNases were determined. Zymographic analysis showed that culture fluid of B. thuringiensis strains along with low-molecular-weight (15-20 kDa) RNases contained enzymes with a molecular weight ~55 kDa and their content depended on the duration and conditions of culturing. Preparations based on B. thuringiensis culture fluid were effective against human influenza virus A/Aichi/2/68 (H3N2). In experiments on mice infected with 10 LD50 influenza virus strain A/Aichi/2/68 (H3N2), we selected effective variants of preparations based on culture fluid of B. thuringiensi strains for preventive administration that provided reliable protection of infected animals (protection coefficient 50%), close to that of the reference drug Tamiflu.

Data on the number and diversity of psychrotolerant yeast isolated from high-altitude and surface samples of atmospheric aerosol from southwestern Siberia are derived from a microbiological study. According to certain phenotypic and genomic characteristics, the yeast isolates are referred to the Saccharomyces, Candida, Sporidiobolus, Aureobasidium, Sporobolomyces, Cryptococcus, Rhodotorula, and some other genera. Both saprophytic and pathogenic microorganisms are detected. Aureobasidium yeast strains are revealed, which actively produce exopolysaccharides and melanin and are promising for biotechnological developments.

The results of studies of a newly isolated Serratia species K-57 strain are presented. The strain is characterized by antiviral activity towards human influenza A/Aichi/2/68/H3N2, vaccinia, mouse smallpox, and herpes simplex-2 viruses. The detected characteristics of the strain, including the data on activities on nucleolytic enzymes, recommend it for the development of therapeutic and preventive antiviral drugs.

Background. To optimize the process of bread wheat breeding for earliness and environmental adaptability, searching for new source material is a crucial task. The ultra-early line Rico (k-65588) – Triticum aestivum var. erythrospermum Koern. – stands out among the bread wheat accessions from the VIR collection for its important adaptive features.Materials and methods. Spring wheat accessions with different speed of development were selected from the VIR collection for this study, along with the ultra-early lines Rifor 1 ... 10 (F6-7 Rico × Forlani Roberto k-42641) and Fori 1 ... 8 (k-65589 ... k-65596) (F4 Foton k-55696 × Rico). Their responses to a short 12-hour day were assessed. Vernalization conditions were 30 days at 3°C. The genetics of plant sensitivity to vernalization and photoperiods was studied using allele-specific primers for the genes Vrn-A1, Vrn-B1, Vrn-D1 and Ppd-D1.Results and conclusions. In the Northwest of Russia, the period from seeding to heading for Rico plants was 39.9 ± 1.49 days, or 14.8 ± 1.22 days less than for the released commercial wheat cultivars. Among the 8400 wheat accessions, studied by the Wheat Genetic Resources Department of VIR in this area from 1948 to 2018, the shortest period from germination to heading was observed in the line Rico: 29 (28–30) days. The absence of response to vernalization in Rico, Fori and Rifor lines was determined by the dominant alleles Vrn-A1, Vrn-B1 and Vrn-D1. Photoperiodism in Rico and partially in Rifor was controlled by at least two genes: Ppd-D1 and Ppd-B1. In the F2 population of Rico hybrids with 8 wheat accessions no transgression was observed beyond the limits of Rico‘s variation. The difference in the development rate between Rico and other wheat accessions is controlled by two or three non-allelic genes. Rifor lines can compete in productivity with commercialized wheat cultivars.

To contribute to the comprehensive study of atmospheric pollution in Siberia, aircraft soundingwas carried out in Northwestern Siberian along the following route: Novosibirsk - Surgut - Igarka - Novosibirsk. This work was aimed at studying the quantity and representation of culturable microorganisms and other biogenic components of the atmosphere at altitudes up to 8,000 m. The air samples were collected to impingers (flow rate 50 ± 5 L/min) where 50 ml of Hanks’ solution (ICN Biomedicals) was used as the sorbing liquid and applied on the fibrous filters. The concentration of biogenic material was recorded, and the concentration and diversity of culturable microorganisms were determined in total protein samples. It was found that the samples of atmospheric air contained 158 mesophilic and psychrophilic microorganisms represented by such genera as Micrococcus, Staphylococcus, Bacillus, Nocardia, Arthrobacter, and Rhodococcus. Also, Actinomycete, yeast and fungal cultures were also isolated. Non-sporiferous bacteria were widely presented at all altitudes. Enzymatic activity of the isolated microorganisms and a number of pathogenicity factors present were investigated. The data on quantity and representation of culturable microorganisms and other biogenic components at altitudes up to 8000 m in Northwestern Siberia were obtained for the first time. It is a significant contribution to the study of the atmosphere of this region. The patterns of the observed biodiversity of microorganisms, associated with the sampling altitude or geographic location, should be determined infurther research.

Cryotolerance in microorganisms from polar regions provides their survival through alternating freezing and thawing cycles. Our research was aimed at biodiversity analysis of culturable bacteria from the King George Island near Antarctica including their antibiotic resistance and cold-adaptive enzymes. Average bacterial density was estimated as 3 × 106 cells/mL but the number of colony-forming units (CFU) was essentially lower - (3.2–9.2)x103 cells/mL. Totally, 83 stable strains were isolated and identified using phylogenetic analysis of 16S rRNA gene nucleotide sequences and phenotypic traits. Main groups were the Gram-negative Pseudomonas and Duganella species as well as Gram-positive Arthrobacter spp. Besides, eubacteria Psychrobacter, Flavobacterium, Clavibacter, Aquaspirillum, Polaromonas, Actinibacterium, Shewanella, Kocuria and families Comamonadacea, Actinobacteridae were found. Genetic diversity of the bacteria was elevated with plasmids of different lengths in 33 strains but no correlation between the plasmids content and antibiotic resistance was found. Among cold-adapted enzymes antioxidant catalases (91.5%), peroxidases (57.5%), alkaline phosphatases (42.2%) prevailed; unspecific exonucleases were revealed in 16.9% strains and restriction endonucleases of type II - in 8.4% strains only. Lypases were detected in 24 strains (28.9%) and could facilitate membrane fluidity at low temperatures. Despite the antibiotic resistance the Antarctic cultivable eubacteria are mainly not pathogenic and may serve as sources of plasmids and cold-adapted enzymes for biotechnology.

In Ukraine, the perspective oil and gas bearing regions are located within the Carpathian-Black Sea segment of the Tethys, and the southern slopes of the East European Platform. We examined the plankton microfossil content from numerous Paleogene samples obtained from outcrop and exploration borehole sections. The interpretation of the large dataset concerning the spatial-temporal distribution of Foraminifera, Calcareous nannofossils and Dinocysts is provided. The characteristics of the stratigraphic distribution of planktonic fossil assemblages in the Paleogene sections, their cyclicity in the formations and the specifics of the zonal subdivision based on the defined correlation levels are given. As a result of an integrated study the biozonal subdivision of Paleogene sediments of Ukraine is substantiated, and an interregional correlation of various facies of the Paleogene sections with the International Stratigraphic Scheme is undertaken.

The purpose was to monitor the bacteriological urine studies in children with urinary tract infection (UTI) in departments of multidisciplinary hospital. 1 838 results of bacteriological examinations of urine samples of children with urinary tract infection were analyzed for 7 years (2007-2013). The obtained data were processed using the methods of parametric analysis. The urine microbial spectrum differed between ambulatory patients and the patients hospitalized in specialized departments, and it also depended on department profile and patient's age. The most frequent uropathogen was E. coli (33,3 ± 7,5) - (65,0 ± 7,5) %. But, a decreasing tendency of E. coli importance in the urinary tract infection has been observed. The leading role in children's UTI etiology in various departments of multidisciplinary hospital also plays Enterococcus faecalis, which is the second most common uropathogen in hospitalized patients with UTI and has paramount importance in the development of UTI in newborns - to (75,0 ± 6,8) %.

Particular concern at the present stage is the health effects of wildfires’ smoke. The aim of the study was to determine the impact of paternal biomass-smoke exposure on offspring’s behavior and cognitive abilities. Male rats were exposed to biomass smoke for four hours/day, five days/week, for four weeks. Average concentration of carbon monoxide and particulate matter of 2.5 μm PM2.5 in the chamber during exposure were 28.7 ± 5.3 mg/m3 and 1.9 ± 0.5 mg/m3, respectively. At the same time, high concentrations of furfural and acetaldehyde were detected in the air environment of the exposure chambers. Offspring was obtained by mating of experimental males with untreated females, immediately after the end of the exposure and after 60 days (long-term period). Offspring were tested by using the Morris water maze and open field at three months of age. Male and female offspring born by mating immediately after exposure demonstrated decreased exploratory behavior, locomotor activity, and spatial navigation, as well as increased anxiety levels. Locomotor and exploratory activity in rats of both sexes from progeny obtained after long-term exposure to smoke had no statistically significant differences when compared to the control; however, the females showed a high level of anxiety and impaired cognitive functions. The recovery period after biomass-smoke intoxication, comparable in duration of spermatogenesis in rats, was an important factor in reducing the risk of developing central nervous system (CNS) disorders in offspring.

The data on insecticidal, antimicrobial, and antiviral activity of Bacillus thuringiensis (Bt) strains isolated in the microbiological study of height and ground atmospheric aerosol samples taken in the South of Western Siberia are presented. Among 36 isolated bacteria determined as related to the Bt species, 15 strains were relegated to the Bt ssp. kurstaki subspecies by results of intraspecific testing and studied for the presence of antagonistic attributes. In spite of long wandering in extreme conditions in the composition of atmospheric aerosols, including higher atmospheric layer (up to 7 km), the isolated Bt ssp. kurstaki strains keep high (inherent to this subspecies) entomopathogenic activity, possessed the ability to inhibit the multiplication of such pathogenic microorganisms as Staphylococcus aureus, Salmonella thyphimurium, Shigella sonnei, Candida albicans, and others, and manifested the ability to effectively neutralize the multiplication of the A/chicken/Kurgan/05/2005 (A/H5N1) avian influenza virus and A/Aichi/2/68 (A/H3N2) human virus. Properties of Bt strains isolated from atmospheric aerosols not only verified their well-known resistance to unfavorable factors of the environment but also exhibited the possibility of using them for developing viricides.

Strains of rod-shaped, facultatively anaerobic, spore-forming bacteria exhibiting negative Gram reaction were revealed after inoculation of soil, water, and silt samples from springs of the Valley of Geysers (Kamchatka) onto complete media at pH 5.0, 7,0, and 9.0 and cultivation at 28–30°C. The bacterial isolates differed in their phenotypic characteristics and in the G + C content of genomic DNA, which ranged from 41.1 to 53 mol %. The analysis of 16S rRNA gene nucleotide sequences of all isolated strains (GenBank EU497635-EU497641) revealed their close homologues among the known species of the genus Paenibacillus. At the same time, all the studied bacilli (Dg-824, Dg-904, Dg-1009, Gi-662, Gi-724, K-58, etc.) differed significantly from the nearest phylogenetic neighbors in their phenotypic characteristics, including the Gram reaction, the DNA G + C content, and a number of other determinative characteristics; therefore, they could not be assigned to previously known species.

Precursor powders in the ZrO2-CeO2-Sc2O3-Al2O3 system have been prepared using the sol-gel method. A physicochemical analysis of the synthesized ceramics, single crystals, and nanofilms based on ZrO2 and HfO2 oxides has been performed. It has been revealed that the introduction of alumina Al2O3 into the ZrO2-based ceramic samples reduces the thermal expansion coefficient and that these ceramic materials possess a high electrical conductivity as compared to the other materials under investigation.

Multi-year monitoring of atmospheric bioaerosol in Southwestern Siberia revealed the presence of a large number of various culturable microorganisms. It is known that viable microorganisms can cause directly or provoke different human diseases. It's very difficult to evaluate the danger represented by each microorganism to man directly. Therefore, a relatively simple method is required for evaluation of potential danger represented to man by the whole assembly of culturable microorganisms in an atmospheric aerosol sample. For bacteria, the method can be based on a number of individual characteristics of each microorganism determined in the course of biochemical and other test required for identification of the detected bacterium, and a number of other tests. It is proposed to classify the measured individual characteristics of bacteria under four groups of indices responsible for: (i) potential pathogenicity for man; (ii) the numbers of bacteria in the sample; (iii) resistance to unfavorable environmental factors; (iv) drug resistance of bacteria. Each of four groups of indices is numerically evaluated by a certain integral index, which quantitatively reflects the contribution of experimentally determined characteristics of bacteria. Expert evaluation of the contribution of each characteristic of microorganisms to the corresponding group of indices is performed. The generalized index of potential danger of culturable bacteria in atmospheric aerosols for human health is presented as the product of four integral indices summarizing the normalized individual integral indices for all bacteria detected in the sample. The work presents the results of measuring the variations of all the above indices for atmospheric air samples collected during one year.

A three-dimensional structure of histo-aspartic protease (HAP), a pepsin-like enzyme from the causative agent of malaria Plasmodium falciparum, is suggested on the basis of homologous modeling followed by equilibration by the method of molecular dynamics. The presence of a His residue in the catalytic site instead of an Asp residue, which is characteristic of pepsin-like enzymes, and replacement of some other conserved residues in the active site make it possible for the enzyme to function by the covalent mechanism inherent in serine proteases. The detailed structures of HAP complexes with pepstatin, a noncovalent inhibitor of aspartic proteases, and phenylmethylsulfonyl fluoride, a covalent inhibitor of serine proteases, as well as with a pentapeptide substrate are discussed.

Oil-oxidizing microorganisms have been sampled in various regions of Siberia and used in strain associations, which degrade n-alkanes of oil from various fields by 64–92% after 6 days of growth in a wide temperature range. These strains are salt-tolerant and psychrotolerant. They are compatible with aboriginal soil microflora. Promising results have been obtained in experiments on growing plants on oil-polluted soil purified with a biodegrader of this series.

Antimicrobial resistance and plasmid profile of Gram-positive and Gram-negative bacterial strains isolated from the urbanized Eltsovka-1 River (Russia) were investigated. Sequencing of the 16S rRNA of of G+ strains showed 99-100% identity to that of Bacillus aerophilus, Bacillus altitudinis, Bacillus amyloliquefaciens, Bacillus anthrancis, Bacillus barbaricus, Bacillus cereus, Bacillus flexus, Bacillus indriensis, Bacillus stratosphericus, Bacillus subtilis subsp. subtilis, Bacillus thuringiensis, Streptomyces albidoflavus, Streptomyces albus, Streptomyces exfoliatus, Streptomyces odorifer, and Streptomyces sampsonii. Sequencing of the 16S rRNA of G-strains was similar in 99-100% to that of Aeromonas bestiarum, Aeromonas encheleia, Aeromonas hydrophila, A. hydrophila subsp. anaerogenes, A. hydrophila subsp. dhakensis, Aeromonas media, Aeromonas molluscorum, Aeromonas popoffii, Aeromonas salmonicida subsp. masoucida, A. salmonicida subsp. pectinolytica, A. salmonicida subsp. salmonicida, Aeromonas punctata, Aeromonas sobria, and Shewanella putrefaciens. The highest percentage (88.4%) of strains was resistant to polymyxin B followed by 69% to lincomycin, 61.5% to benzilpenicillin, 57.7% to ampicillin, and 50% to carbenicillin. A low level of resistance (4%) was found to kanamycin (8%), to streptomycin (11.5%), to neomycin and tetracycline, and (15%) to erythromycin. No resistance was found to gentamycin, monomycin, and chloroamphenicol. The majority (80.7%) of strains was multidrug-resistant. Ninety-two percent of all strains carried plasmid DNA of various sizes.

A continuous chain of hydrogen bonded groups, which forms cross-hands interaction between domains in molecules of pepsin-like enzymes, has been revealed. The chain contains a pair of 6 symmetrically related hydrogen bonds between main chain atoms and the two conserved water molecules. The peptide groups forming hydrogen bond with the inner oxygens of the active carboxyls are important elements of the chain. The so-called "fireman grip" hydrogen bonding, consisting of a pair of the two symmetrically related bonds, is an integral part of this system of interactions. One of the water molecules in this system has a zero accessibility and forms a very short hydrogen bond with the active site interacting peptide group. This chain connects tightly the two regions of domains which have a high correlation in conformational mobility. The retroviral enzymes have an abortive chain of the interdomain interaction in this region which is reduced to the "fireman grip" net.

Genetic and biochemical methods and morphological examination were used to study microorganisms isolated from samples of deep drilling of the Lake Baikal bottom sediments. Based on blot hybridization patterns, the strains investigated were divided into several groups according to the degree of homology of their genomic DNA. Morphological, biochemical, and ultrastructural characteristics of bacterial strains are described, and their compliance with the genomic analysis data is demonstrated.

Glutamate decarboxylase (GAD) is a pyridoxal enzyme that catalyzes the conversion of l-glutamate into γ-aminobutyric acid and carbon dioxide. The Escherichia coli enzyme exists as two isozymes, referred to as GADα and GADβ. Crystals of the complex of the recombinant isozyme GADα with glutarate as a substrate analogue were grown in space group R3, with unit-cell parameters a = b = 117.1, c = 196.4 A. The structure of the enzyme was solved by the molecular-replacement method and refined at 2.05 A resolution to an R factor of 15.1% (Rfree = 19.9%). The asymmetric unit contains a dimer consisting of two subunits of the enzyme related by a noncrystallographic twofold axis which is perpendicular to and intersects a crystallographic threefold axis. The dimers are related by a crystallographic threefold axis to form a hexamer. The active site of each subunit is formed by residues of the large domains of both subunits of the dimer. The coenzyme pyridoxal phosphate (PLP) forms an aldimine bond with Lys276. The glutarate molecule bound in the active site of the enzyme adopts two conformations with equal occupancies. One of the two carboxy groups of the glutarate occupies the same position in both conformations and forms hydrogen bonds with the N atom of the main chain of Phe63 and the side chain of Thr62 of one subunit and the side chains of Asp86 and Asn83 of the adjacent subunit of the dimer. Apparently, it is in this position that the distal carboxy group of the substrate would be bound by the enzyme, thus providing recognition of glutamic acid by the enzyme.

The primary structure of the so-called histoaspartic protease from Plasmodium falciparum has a very high percentage of identity and homology with the pepsin-like enzyme plasmepsin II. A homology modeling approach was used to calculate the three-dimensional structure of the enzyme. Molecular dynamics (MD) simulations were applied to find those structural properties of the histoaspartic protease that had a tendency to remain stable during all runs. The results have shown that hydrogen-bonded residues Ser37-His34-Asp214 are arranged without any strain, in a manner that resembles the active site of a serine protease, while Ser38 and Asn39 take up positions appropriate to formation of an oxyanion hole. Although there are several important differences between the enzyme and plasmepsin II, all of the structural features associated with a typical pepsin-like aspartic protease are present in the final model of the histoaspartic protease. A possibility that this enzyme may function as a serine protease is discussed.

In addition to previous studies, 30 crystal structures of retroviral proteases corresponding to the highest resolution were inspected to analyze the interactions of the active carboxyls with surroundings groups. The outer oxygens of the active carboxyls in retroviral enzymes form contacts only with the water molecule participating in catalysis. This is an important difference between retroviral proteases and pepsin-like enzymes, which form a net of hydrogen bonds of these outer oxygens with residues neighboring the catalytic site in 3D structures. At the same time, it was found that in all aspartic proteases the inner oxygens of the active carboxyls are also involved in the chain of interactions through peptide groups Thr–Gly adjacent to the active residues. Polarization of these peptide groups influences the donor–acceptor properties of the active carboxyls. The found chain of interactions is more extensive in retroviral than in pepsin-like proteases; however, its main part is conserved for the whole class of these enzymes. Some implications of the role of these interactions are discussed.

Amino acid sequences of E. coli glutamate decarboxylase (GADa) and those of 36 GAD of different origin were compared by pairwise alignment using computer program CLUSTAL. GADalpha and plant enzymes showed 59.8-67.8% subunit homology, GADalpha and other bacterial GAD--49.8-77.6%, whereas GADalpha and animal enzymes--13.9-58.8%. Two PLP domains exhibited higher homology comparing to that of the whole subunit in the case of GAD67, plant (68.4-73.9%), and bacterial (46.7-83.2%) enzymes. The alignment of PLP-domains of 37 GAD, three group II decarboxylases, and two pyridoxal enzymes with known 3D structures (bacterial ORD and mAAT from chicken heart) allowed us to reveal conserved residues of the active sites. Their functional role is discussed. Modelling of the PLP-binding sites in active centers for GADalpha and human brain GAD67 was done using the Swiss-PdbViewer homology modelling program. Although the homology between GADalpha and GAD67 is rather low, structural similarity of their active sites allows us to consider here a functional convergence. Thus, glutamate decarboxylation by GADalpha may be helpful for understanding general mechanism of this reaction.

To elucidate the role of amino acid residues adjacent to the catalytic site of pepsin-like enzymes, we analyzed and compared the crystal structures of these enzymes, their complexes with inhibitors, and zymogens in the active site area (a total of 82 structures). In addition to the water molecule (W1) located between the active carboxyls and playing a role of the nucleophile during catalytic reaction, another water molecule (W2) at the vicinity of the active groups was found to be completely conserved. This water molecule plays an essential role in formation of a chain of hydrogen-bonded residues between the active site flap and the active carboxyls on ligand binding. These data suggest a new approach to understanding the role of residues around the catalytic site, which can assist the development of the catalytic reaction. The influence of groups adjacent to the active carboxyls is manifested by pepsin activity at pH 1.0. Some features of pepsin-like enzymes and their mutants are discussed in the framework of the approach.

Forty one patients with AML (M01 4 patients, M11 5, M21 7, M41 8, M5a1 16, and M61 one patient) have been studied. Cytochemical reactions (MPO, CAE, AcP, ANAE, NE, PAS) and immunological detection of antigens expression (indirect immunoperoxidase, APAAP methods and, in some cases, flow cytometry) were performed. The definition of typical phenotypical pattern for discrete FAB-variants AML was carried out. Significant heterogeneity of monoblasts was revealed. Cases of AML, M5a with unusual phenotypical features were discovered. Its origin from hierarchy of hematopoietic stem cells is discussed.

A detailed inspection of the highly refined three-dimensional structure of porcine pepsin (1) offers the explanation of important properties of this enzyme. One of the first results of these studies was the detection of charged groups responsible for unusual electro-phoretic behavior of pepsin and its abnormal stability in extreme acidic conditions (1,2). However, very important steps of these investigations have to explain the structural grounds for catalytic properties of pepsin. This problem is closely connected with the analogous research on other aspartic proteinases which share the common type of the active site structure with that of pepsin. The extensive X-ray crystallographic studies of their complexes with various inhibitors have culminated in description of the generally accepted mechanism of their catalytic activity (3,4,5). Three-dimensional structure of all aspartic proteinases gives a clear explanation of the preference for hydrophobic residues flanking the scissile bond of their substrates. However, evidence which would help in understanding the prominent difference between a rather wide specificity of pepsin and a strict requirement for the renin substrate, as well as for specificity of chymosin towards κ-casein, is not in hand. This phenomenon cannot be explained solely on the basis of differences of their substrate binding pockets.

Chymosin molecules in the crystal lattice have Tyr77 occluding the S1 S3 substrate binding pockets suggesting that the enzyme is self-inhibited. An analysis of this structure in conjunction with its comparison with pepsin has shown that this is most probably an intrinsic property of the enzyme. It also indicates that chymosin's substrate specificity may be dependent upon the ability of the substrate to displace the tyrosine ring from the binding pockets. This analysis also implies that active and self-inhibited forms of other aspartic proteinases can exist in solution helping to explain the results of kinetic studies of these enzymes.

Pepsin has several properties which are markedly different from those common for other proteins. It has a very low pH optimum for the hydrolysis of different substrates and a high activity at pH 2. This implies a very stable tertiary structure under conditions in which many proteins are fully denatured. These properties of pepsin are critical for its physiological function which takes place in the extreme acid conditions of the gastric lumen. There the unfolded hydrophobic cores of the proteins to be cleaved are exposed to the first hydrolytic attack by pepsin. Another very specific property of pepsin is its extremely low isoelectric point. It has a net negative charge in the range of low pH values including the pH optimum for catalytic activity. The proteins to be cleaved have a net positive charge in this range of pH. These molecular features of pepsin are closely interdependent as all of them are the consequence of the specific arrangements and interaction of the charged groups in the three-dimensional fold of the enzyme. Data on the refined porcine pepsin A structure at 1.8 A resolution (Sielecki et al., 1990) have pointed towards their explanation. Porcine pepsin has also been refined at 2.3 A resolution in the monoclinic crystal form by Abad-Zapatero et al. (1990) and in the hexagonal crystal form by Cooper et al. (1990).

Domains of aspartic proteinase molecules have the same fold (Tang et al., 1978) while their primary structures show no homology except small segments of a few amino acid residues located in the region of the active site in the three-dimensional structure. One may ask: is it possible to detect a common specific property of amino acid sequences of both domains which can explain the tendency of their chains to fold by the same manner? In other words does a consensus template for the specific aspartic proteinase fold exist? Interactions between different segments of a polypeptide chain providing formation of a central hydrophobic core of a protein molecule determine mainly the geometrical type of protein folding. If a consensus template for the specific aspartic proteinase fold really exists it must concern the formation of central hydrophobic cores in domains.

The molecular structure of the archetypal aspartic proteinase, porcine pepsin (EC 3.4.23.1), has been refined using data collected from a single monoclinic crystal on a twin multiwire detector system to 1.8 A resolution. The current crystallographic R-factor (= sigma parallel to Fo/-/Fc parallel to/sigma/Fo/) is 0.174 for the 20,519 reflections with /Fo/ greater than or equal to 3 sigma (Fo) in the range 8.0 to 1.8 A (/Fo/ and /Fc/ are the observed and calculated structure factor amplitudes respectively). The refinement has shown conclusively that there are only 326 amino acid residues in porcine pepsin. Ile230 is not present in the molecule. The two catalytic residues Asp32 and Asp215 have dispositions in porcine pepsin very similar to the dispositions of the equivalent residues in the other aspartic proteinases of known structure. A bound solvent molecule is associated with both carboxyl groups at the active site. No bound ethanol molecule could be identified conclusively in the structure. The average thermal motion parameter of the residues that comprise the C-terminal domain of pepsin is approximately twice that of the residues in the N-terminal domain. Comparisons of the tertiary structure of pepsin with porcine pepsinogen, penicillopepsin, rhizopus pepsin and endothia pepsin reveal that the N-terminal domains are topographically more similar than the conformationally flexible C-terminal domains. The conformational differences may be modeled as rigid-body movements of "reduced" C-terminal domains (residues 193 to 212 and 223 to 298 in pepsin numbering). A similar movement of the C-terminal domain of endothia pepsin has been observed upon inhibitor binding. A phosphoryl group covalently attached to Ser68 O gamma has been identified in the electron density map of porcine pepsin. The low pKa1 value for this group, coupled with unusual microenvironments for several of the aspartyl carboxylate groups, ensures a net negative charge on porcine pepsin in a strongly acid medium. Thus, there is a structural explanation for the very early observations of "anodic migration" of porcine pepsin at pH 1. In the crystals, the molecules are packed tightly into a monoclinic unit cell. There are 190 direct contacts (less than or equal to 4.0 A) between a central pepsin molecule and the five unique symmetry-related molecules surrounding it in the crystalline lattice. The tight packing in this cell makes pepsin's active site and binding cleft relatively inaccessible to substrate analogs or inhibitors.

Using the most effective rapid method for the detection of restriction endonucleases (ENases) in microorganisms, 32 thermophilic producers have been isolated. All strains belong to the genus Bacillus. Thermostable isoschizomers of ENases, such as AvaI, BbvI, BbvII, BelI, BsasI, BsiYI, BsrI, BstEII, BstNI, Cfr101, ClaI, FspI, HaeIII, HpaII, Ksp632I and SfeI, were isolated.

An account of x-ray crystallographic studies of monoclinic porcine pepsin crystals is presented. The chain fold specific for aspartyl proteases is described in detail. As the results of 2-A refinement have shown, the actual structure is that of ethanol-inhibited pepsin. The structure, although close to those of fungal aspartyl proteases, has some specific features: one of them is an insertion near the S'1 site which restricts the position of dipeptide substrates and makes their productive binding more probable than in the fungal enzymes. 3-A resolution data on the binding of the dipeptide phenylalanyl-diiodotyrosine methyl ester are discussed.

Pepsin was the first object used to obtain x-ray photographs of protein crystals (1) and the second protein to be crystallized (2). J. Northrop developed the method of porcine pepsin crystallization in this well known investigation (2). Two of the crystal forms of pepsin that have been described, the first hexagonal form has been studied by J. Bernal and D. Crowfoot (1), and by M. Perutz (3). The unit cell of hexagonal pepsin crystals was too large, however, for studies of it to continue at the initial stage of the development of protein crystallography. The second form of the crystal was more suitable for x-ray crystallographic studies.

– Two cases of aseptic meningitis with simultaneous presence of antibodies to lymphocytic choriomeningitis (LCM) and mumps viruses were observed. In the 1st patient antibodies to both viruses appeared in sera and cerebrospinal fluid (CSF). The 2nd patient displayed rising serum antibodies to both viruses and CSF antibodies to mumps virus. Immunological findings and clinical features of the patients are discussed.

Microbiological analysis of samples of sedimentary rocks from various eras of the geological history of the Baikal rift has enabled us to isolate a large number of microorganisms that can be classified into new, previously undescribed species. The present work deals with the identification and study of the morphological, biochemical, and physiological properties of one such strain, Che 82, isolated from sample C-29 of 3.4-3.5 Ma-old sedimentary rocks taken at a drilling depth of 146.74 m. As a result of our investigations, strain Che 82 is described as a new bacterial species, Roseomonas baikalica sp. nov., belonging to the genus Roseomonas within the family Methylobacteriaceae, class Alphaproteobacteria.