[Free-radical reactions in Daphnia after low doses of γ-irradiation in vivo].

A violation of free-radical reactions has been found by the method of free-radical copolymerization in the two groups of Daphnia magna exposed to 100 and 1000 mGy of gamma-rays and their non-exposed first generation progeny. The method is based on a quantitative radiometric registration of the polymerization process that develops in the cells of a multicellular organism in tissue in proportion to the existing number of free radicals. The fact of the increased level of free radicals may be indicative of the hereditary transgenerational effect and the cause of lower survival of Daphnia in both generations. However, the effect of a reduced survival rate does not persist in the second generation, which can be explained by the effect of radiation on the embryos of the first generation after acute irradiation of parents.

[Methyltetrazolium bromide (MTT) was applied for bioassay of environmental radioactivity in vivo].

The MTT-assay is a colorimetric assay that measures the activity of enzymes that reduce MTT (a yellow tetrazolium bromide) in living cells. The MTT-test has been traditionally applied for the analysis of drug cytotoxicity in vitro. In our study MTT-assay was first applied for the investigation in vivo of the mechanisms of non-targeted effects of radiation and development of stress in multicellular crustaceans Daphnia magna. MTT test was based on the analysis of variation in the optical density of the irradiated Daphnia, which is proportional to the amount of formazan formed as a result of restoring MT with the help of dehydrogenases. So this indicator measures the effectiveness of the toxic effect of gamma-radiation. It describes the change in the balance of normal and damaged cells, suppression of the total dehydrogenase activity and other factors that are responsible for the metabolism of a multicellular organism. Daphnia were exposed to acute 60Co gamma-rays. According to our data, the effectiveness of toxicity was significantly raised in the two groups exposed to 100 and 1000 mGy of gamma-rays. Given the results of in vitro studies, our data therefore indicate that the compromised viability of irradiated Daphnia may be attributed to the cytotoxic effects within the dose-range of 100 and 1000 mGy. The results obtained in this study show that Daphnia represent a very useful experimental model, which allows a very efficient and quick analysis of many aspects of non-targeted effects of ionising radiation.

[The change of Daphnia magna viability after low doses of gamma-irradiation].

The gamma-irradiation in the dose 0.001 Gy didn't influence to the Daphnia magna Straus survival in the parents generation, cultivating during 30 days. At the some time the irradiation in dose 0.01 Gy had considerable increased the level of them died. This reaction was saving during the increase of the doses to 0.1, 1 and 20 Gy. So in this doses the interval had been gradual and didn't depend from dose, decreasing the number of this population, which significant top the control level. In more high doses--100, 250 and 600 Gy was observed the transfer to the stronger lethal effects, which increased with the doses' grow. Daphnia are the plankton animals, which live in a huge numbers in fresh reservoirs. So the decrease of their population after gamma-irradiation in low and high doses has been interested as a radioecology problem.

[Spontaneous motional activity of paramecium Spirostomum ambiguum after gamma-irradiation in a broad variety of dose as a bioassay].

The spontaneous motional activity of paramecium Spirostomum ambiguum Ehrbg. has high sensitivity to the gamma-irradiation. The increase of this parameter has been observed just after irradiation in the 0.1 Gy. It is approximately on the similar level (about 35% below control) in a broad variety of doze (to 850 Gy inclusive). After that the dozes 1000-1500 Gy has been obtained, the effect became stronger. The present result has been interesting in the question of the behavior's reaction unicellular using in the indication of the radioactivity contamination of the aquatic aria. And also it is actual in the common problem of the irradiation activity on the biota.