Early toxic effects of fumonisin B1 in rat liver.

Mycotoxin fumonisin B(1) (FB(1)) is hepatotoxic and carcinogenic in experimental animals. It is known that long-term exposure of experimental animals to FB(1) causes apoptosis and lipid peroxidation. In this study, male adult Wistar rats were treated with single FB(1) doses (5, 50, and 500 microg/kg b.w.) and sacrificed 4, 24, and 48 hours after treatment. Parameters of oxidative stress, histopathological changes, and DNA damage were monitored in the liver of treated and control animals. Parameters of oxidative stress were not affected by such treatment. A significant increase in apoptotic cells appeared in animals when 5 microg/kg b.w. dose was given and sacrificed after 24 hours with further increase at higher doses. In contrast to the number of mitotic figures and karyomegaly seen mostly at lower FB(1) doses, necrosis was the prominent feature at higher doses. Significant increase in liver cells DNA mobility was observed 48 hours following treatment with 50 and 500 microg/kg b.w. as compared to control (tail length 15.2 +/- 0.3, 16.4 +/- 0.5, and 13.5 +/- 0.1 mum, respectively). Tail intensity appeared to be more sensitive parameter for detecting DNA damage even at 5 microg/kg b.w. after 48 hours (1.69 +/- 0.27% DNA; control 0.59 +/- 0.11% DNA). This study proved that FB(1)-induced DNA damage is time- and dose-dependent, and that it could be caused in Wistar rats by a single dose.

Endosymbiotic alga from green hydra under the influence of cinoxacin.

Cinoxacin (Cxn) showed a strong effect on the endosymbiotic alga Chlorella; it was significantly damaged. Changes in algal color, position, structure and ultrastructure were found. In some algal cells ultrastructures were completely destroyed. The antichloroplastal and antimitochondrial effect was especially expressed. Damage to the thylakoid system of chloroplasts was more pronounced with increasing Cxn concentration. Some of the mitochondria were swollen and some of them were completely destroyed. From the evolutionary point of view, the correlation between antibacterial, and antichloroplastal and antimitochondrial effect of Cxn points to the evolutionary connection of chloroplasts and mitochondria with eubacteria.

Toxicity testing of herbicide norflurazon on an aquatic bioindicator species--the planarian Polycelis felina (Daly.).

Norflurazon is a bleaching, preemergence herbicide. Due to its mobility and long half-life it presents a potential for groundwater contamination. The aim of our study was to investigate toxic effects of norflurazon on non-targeted aquatic bioindicator organism, the planarian Polycelis felina (Daly.). Animals were exposed to water solutions of norflurazon in concentrations 200, 20, 2 and 0.2 microM. Mortality, locomotive and morphological changes were monitored. Histological changes were studied both on treated and control animals with light microscopy. The primary DNA damage on single planarian cells was studied using the alkaline comet assay. Three comet parameters were studied: tail length, percentage of DNA in comet tail and tail moment. The results showed that norflurazon caused mortality, locomotive, morphological and histological changes in treated animals compared to corresponding controls. The most prominent histological changes were damage of the outer mucous layer, lack of rhabdites, damage to epidermis and extensive damage to parenchyma cells. The results of alkaline comet assay indicated that norflurazon in concentrations of 2 and 0.2 microM induces significant increase of primary DNA damage in planarian cells compared to the corresponding control animals. The mean values of all three measured parameters were significantly elevated on the fourth day of the treatment compared with the first and the seventh day. Based on the results of mortality and locomotive observations, we conclude that the fourth day of the treatment represents a certain threshold within planarian metabolism followed by the beginning of detoxification and recovery. However, histological preparations and comet data statistics show results indicating that high toxicity on the seventh day of the treatment gave the results of decrease of DNA damage due to the tissue/cell damage (apoptosis) and not recovery. The present study showed the ability of norflurazon to induce a wide range of different toxicological responses in freshwater planarian Polycelis felina (Daly.).

The impairments of neoblast division in regenerating planarian Polycelis felina (Daly.) caused by in vitro treatment with cadmium sulfate.

The effects of cadmium sulfate on the neoblast mitotic activity in regenerating planarian Polycelis felina (Daly.) were investigated. Mitotic abnormalities and chromosomal aberrations were evaluated after 6-h treatment and 24-h recovery period. The blastema were fixed, and examined cytologically through routine lactoorceine squash preparations. Mitotic indices were also determined. Cadmium sulfate induced a dose-dependent decrease in neoblast mitotic activity, accompanied with disturbances in distribution of cells over mitotic phases. Different cytological abnormalities with varying frequency were observed. Marked mitotic depression was concentration-dependent. Toxic effects of cadmium in regenerating planarian were mainly associated with mitotic spindle disturbances. Immediately after treatment mitotic abnormalities were prevalent over chromosomal and C-mitosis was the most prominent one. After 24-h recovery period a prevalence of mitotic over chromosomal aberrations was still present in animals treated with two higher concentrations of cadmium sulfate. However, the proportions of cells with chromosome stickiness in all treated animals were significantly increased compared to their post-treatment values. Observed mitotic impairments could be related to mitotic arrest contributing to retardations and delays, especially in animals treated with the highest concentration tested. The results obtained indicated usefulness of short term invertebrate assays as an alternative to in vitro pre-screening of toxic chemicals.

Effect of insecticides (Dimiline WP 25, Torak EC 24 and Gamacide 20) on hydra (Hydra vulgaris Pallas).

Investigations showed that the three insecticides used had the most damaging effect upon hydra immediately after treatment. The tentacles and the hypostome are the parts most often damaged. Inse the affected cells, lesions appear in the intracellular membranes, the nucleus shell and the membranes of the mitochondria, Golgi complex and the endoplasmic reticulum, while the cell membrane is preserved. The damaged parts of the body regenerate within three days. Zymogen cells play a significant role in the course of regeneration. They dedifferentiate into gastrodermal interstitial cells and later into other types of cells of the ectoderm and the gastroderm. Apart from their intense participation in regeneration, these totipotent cells also invariably participate in the formation of new hydra buds. It was observed that Dimiline WP 25 and Torak EC 24 in the concentrations used stimulate asexual reproduction of this animal.

Elimination of zymogen cells and their derivates in Hydra.

Budles and one-budded hydras were exposed to action of antimite (N-methyl-bis-chlorethylamine hydrochloride, Pliva, Zagreb) in 7 mg/150, 7 mg/200 and 7 mg/250 ml concentrations. All these concentrations caused exterior morphological and cytological changes of the hydra body. In the ectodermal layer interstitial cells gradually disappeared, and then followed enidoblasts and enids. The discussion deals with interstitial cells in a normal untreated animal and possible differentiation of these cells in enidoblasts and enids after the action of antimite. Antimite prevents mitosis, but it does not stop differentiation of some of the cells into other cell types. In the gastrodermal layer the greatest changes which are caused by this cytostatic can be seen on zymogen cells. Their shape, cell structure and position in the gastroderm is changed. The results show that zymogen cells after the antimite action have a limited ability of dedifferentiation into gastrodermal interstitial cells, and that their ability to differentiate into mucous cells lingers a longer time. This depends upon their age. Only the hydras which were acted upon by such a dose of antimite that does not prevent division at last some of the zymogen cells can survive and wholly continue their development.