Hepatitis A in Estonia (1990-1999)

During recent 10 years (1990-1999) essential changes occurred the epidemiology of viral hepatitis A (VHA) in Estonia: simultaneously with a decreased level of morbidity (morbidity rate per 100,000 of the population was 78.4 in 1990 and 7.7 in 1996, or 1,241 and 112 cases, respectively), a shift in the age structure of patients from children of preschool age to older age groups took place. Everyday contacts were the main established route of VHA transmission in recent years, but in more than 80% of cases the risk factors of the virus transmission remained obscure. During the regional outbreak of VHA in North Estonia in 1998 (937 out of 989 cases registered in the country) a rise in morbidity was observed among young people aged 15-29 years, when a wide spread of parenteral viral hepatitides B and C and drug addiction were registered in this region. During this outbreak VHA was transmitted mainly through everyday contacts. Still the considerable prevalence of injection drug users who practiced the group use of syringes and needles and took drugs from common containers, a sufficiently high level of the mixed forms of the disease (more than 18% of all registered cases of VHA), detected for the first time, make it possible to suggest that the parenteral transmission route could appear among persons belonging to the above mentioned group. Vaccination is regarded as the most effective measure for the prophylaxis of VHA.     

Specific biological features of opportunistic bacteria determining dysbacteriosis in the composition of the large intestine normal microflora

Dysbiotic manifestations in the gastrointestinal tract are widely spread. They are characterized by a prolonged, persistent course with the tendency to transition to the chronic form and poorly respond to corrective treatment. The occurrence of high concentrations is 70% for Klebsiella oxytoca, while for K. pneumoniae--within the limit of 30%. The most topical problem is colonization of the intestinal mucosa in children aged up to 1 year by Klebsiella, the seeded bacteria retaining their capacity for growth for up to 2-3 years despite the use of probiotics. As shown in this study, the occurrence of Klebsiella and the level of the antilysozyme and "antiinterferon" activity of these bacteria, their resistance to antimicrobial preparations increase, correlating with the level of dysbiotic disturbances.     

Activity of the corn Spm transposon system in transgenic plants Orychophragmus violaceus (L.) O.E. Schulz obtained by both direct transfer of DNA to protoplasts and agrobacterial transformation of root explants

Transposon mediated insertional mutagenesis is one of the approaches for the unique gene cloning. A wild species of Cruciferae family Orychophragmus violaceus (L.) O.E. Schulz, which is of interest for practical breeding as a donor of improved plant oil, was an object of the investigation. Plasmid construction used in the experiments included selective NPT II gene, reported GUS gene serving as an excision marker, structural BAR gene located within the dSpm element and Spm transposase. The GUS gene of this plasmid had not his own promoter and became functional only after Spm-transposition. Transformed Orychophragmus violaceus (L.) O.E. Schulz. plants were obtained by direct mesophyll protoplast transformation as well as Agrobacterium tumefaciens-mediated root explant transformation. Gene transfer and the transposition event were confirmed by the GUS activity and the PCR analysis. Relative transformation efficiency using protoplasts was 5.8%.     

Molecular and cellular aspects of development of arbuscular mycorrhizal symbiosis and its role in plant life

Development of arbuscular mycorrhizal (AM) symbiosis with plant root system in term of molecular and cellular events have been analysed. A role of AM symbiosis in plant life has been discussed. Molecular methods for analysis of arbuscular mycorrhizal fungi have been described.     

Conjugation resistance to Fusarium graminearum Schwabe with multiple molecular forms of some enzymes in winter wheat

Electrophoretic spectra of multiple molecular forms of peroxidase (EC 1.11.1.7), superoxide dismutase (EC 1.15.1.1), phenol oxidase (EC 1.10.3.1), and cytochrome oxidase (EC 1.9.3.1) in seedlings of two aegilops species and eleven genotypes of bread winter wheat differing in the level of their resistance to Fusarium infection are presented. Several izoforms of peroxidase, phenol oxidase, and superoxide dismutase correlate with the level of resistance to Fusarium. Infection of plants with the pathogen enhances expressiveness of some multiple forms of enzymes. Such response to infection in less pronounced in the sensitive genotypes as compared with that in the resistant ones.     

Selection of ergot alkaloid producers by induced mutagenesis

Using the induced mutagenesis technique, A series of genetically modified Claviceps sp. VKM F-2609 strains that display high levels of agroclavine and elymoclavine synthesis were selected by induced mutagenesis. Compared to the parent strain, c106 displayed a 40-fold higher level of agroclavine synthesis, and c66 displayed an eightfold higher level of elymoclavine synthesis. The levels of synthesis of other alkaloids were decreased in these strains. The effects of various carbohydrates on the strain growth and ergot alkaloid biosynthesis was then investigated in both the parent strain and c106. The largest amount of agroclavine was synthesized by c106 strain growing on a medium with maltose.     

Amylases of the fungus Aspergillus flavipes associated with Fucus evanescens

A promising producer of extracellular amylases, Aspergillus flavipes, was selected from 245 strains of marine fungi. Depending on the conditions of growth, this strain produced diverse amylolytic complexes. When grown on medium containing peptone and yeast extract (pH 7.0), A. flavipes synthesized three forms of amylase, differing in pH optimum (5.5, 6.0, and 7.5). A single form of the enzyme was synthesized either in the absence of peptone from the medium or at the initial pH value of the medium, equal to 8.6. The activity of the isolated amylase forms decreased in the presence of proteolytic enzymes. New, highly stable forms of amylase (with pH optima of 5.5 and 7.5 and maximum activity at 60-80 degrees C) were synthesized in the presence of diisopropyl fluorophosphate, an inhibitor of proteases.     

Factors contributing to roquefortine yield variability during cultivation of penicillium roquefortii

Variability in the roquefortine yield was shown to be associated with its consumption by the mycelium during isolation of the end product, which depended on temperature, time of culture liquid storage, and biomass concentration. This was also related to the presence in chloroform of chlorocarbonic acid ethyl ester that reacted with roquefortine.     

Content of alginic acid and fucoidan in fucus algae of the Barents sea

Seasonal changes in the content of alginic acid and fucoidan have been studied in four species of fucus algae from the Barents sea: Fucus vesiculosus, F. distichus, F. serratus, and Ascophyllum nodosum. These polysaccharides are accumulated in the biomass of the algae during summer and autumn. To ensure complete processing of fucus algae it is recommended that the raw material be harvested within this period.