T. V. Kuznetsova

Change of salinity of medium as a function loading in estimating functional state of the crayfish Astacus leptodactylus

Benthic invertebrates are widely used in toxicological research and in automated biomonitoring systems for assessing water quality. However, development of criteria of physiological performance is still required for identification of candidate animals. Assessment of an organism’s performance proposed in the paper is based on standard test treatments of different magnitude and exposure time. With freshwater crustaceans, such a treatment (functional stress) may be performed by changing water salinity by 1‰ through addition of sodium chloride. A non-invasive cardiac rhythm recording method has been used to reveal the response of the cardiovascular system of crayfish to this treatment.

Evaluation of functional state of crayfish Pontastacus leptodactylus in normal and toxic environment by characteristics of their cardiac activity and hemolymph biochemical parameters

The work deals with study of basic characteristics of cardiac activity (heart rate—HR and stress-index—SI) and hemolymph protein parameters in the crayfish Pontastacus leptodactylus. The main criteria of the crayfish selection are developed for formation of the animal reference groups available for subsequent toxicological experiments. The action of a model toxicant, hydroquinone (often present in waste water), at a concentration of 1 g/l on parameters of the crayfish cardiac activity at various exposition time, its effect on circadian cardioactivity and on the hemolymph total protein were studied. At its short-term action, hydroquinone produced a temporary increase of HR and stress-index, but had no marked effect on total protein parameters in hemolymph. At long action (for one day), hydroquinone led to a considerable tachycardia, disturbance of the circadian cardioactivity and to a decrease by 40% of the hemolymph total protein. In 50% of cases the toxicant caused death of the animals either in the course of its short-term action or at period of washout from the toxicant. Mechanisms of the toxic action of hydroquinone at various levels of organization are discussed.

In situ measurements of cardiac activity characteristics in indigenous macrobenthic invertebrates for water quality bioindication

The paper presents the development of non-invasive bioelectronic system of cardiac activity monitoring for the purposes of water quality indication, the potential of the system and the perspectives of simultaneous use with other systems of real time environmental monitoring.

Comparative assessment of surface water quality through evaluation of physiological state of bioindicator species: Searching a new biomarkers

Paper presents the development and approbation of methodological approach to assess environmental quality through testing of indigenous invertebrates cardiac responses. It was shown that method could be useful in ecotoxicological studies as well as in ecosystem health assessment.

Hepatitis E virus infection in different groups of Estonian patients and people who inject drugs

BACKGROUNDnPreviously we demonstrated a high prevalence of hepatitis E virus (HEV) in domestic pigs and wild boars, the main reservoir and possible source of HEV infections in humans. But so far there are no reports about spread of HEV in Estonian human population.nnnOBJECTIVESnThe present study aimed to determine the prevalence and genotyping of HEV in different groups of the Estonian adult population.nnnSTUDY DESIGNnTotally 1426 human serum samples were tested (763 patients with clinically diagnosed nonA/B/C hepatitis, 176 hemodialysis patients, 282 patients with suspected HEV infection and 205 people who injected drugs (PWID)). Presence of anti-HEVantibodies was assessed by ELISA and confirmed by immunoblotting. All anti-HEV positive sera were analyzed for RNA by qPCR. Amplified ORF2 region was sequenced and used for phylogenetic analysis.nnnRESULTSnAntibody assay revealed 49 samples from 1426 (3.4%) with acute (17) or past (32) HEV infection. HEV RNA was detected in 10 anti-HEV IgM positive samples, including 9 samples from patients with suspected HEV infection and 1 hemodialysis patient. Anti-HEV IgG were found in 7.8% patients with suspected HEV infection, in 4% hemodialysis patients, in 2.4% PWID and in 1.96% patients with nonA/B/C hepatitis. All groups demonstrated a trend to share of anti-HEV seroprevalence increasing with age. Phylogenetic analysis of 9 HEV RNA sequences revealed that 3 sequences belonged to HEV genotype 1; 6 ones to genotype 3 (1 sequence belonged to sub-genotype 3a, two ones - sub-genotype 3e, and three ones - to sub-genotype 3f).nnnCONCLUSIONSnDespite the high seroprevalence among domestic pigs, no evidence of HEV transmission from Estonian pigs to humans was found. The results of our study suggest that HEV infections in Estonia are most likely associated with travel or with consumption of imported food products.

Influence of the White Sea sponge Halichondria panicea (Pallas, 1766) on physiological state of the blue mussel Mytilus edulis (Linnaeus, 1758), as evaluated by heart rate characteristics

During laboratory testing it was shown that the presence of the White Sea sponge Halichondria panicea on the shell of the mussel Mytilus edulis negatively affects the functional state of the mollusk as expressed in the increased heart rate recovery time after functional test loads (a 50% water salinity drop for 1 hour). It was found that the degree of this negative influence rises with an increase both in the projective cover of mussel shells by the sponge and in the size/age parameters of mussels.

A New Escherichia coli Strain Producing Human Tumor Necrosis Factor

An Escherichia coli strain producing human tumor necrosis factor (TNF-α) was obtained using a semisynthetic gene partially optimized in respect of codon composition and a phage T7 promoter. The expression product was accumulated in cells as inclusion bodies in a yield of 50–70 mg/l of culture medium. The recombinant TNF-α in the form of inclusion bodies was used for immunization of rats to give a polyclonal antiserum. The resulting antibodies were specific under the immunoblotting conditions to the antigen used for the immunization. A dilution-based refolding procedure was developed; it provided a yield of soluble protein exceeding 85%.