[Behavior of monogenea of the genus Dactylogyrus under extreme temperatures].

Behavior of monogeneans of the genus Dactylogyrus under low (2-5 degrees C) and high (28-34 degrees C) temperatures was studied. It is established, that under extreme conditions movements of monogeneans and egg laying become more intensive. After the last egg is laid, the parasites become motionless, their bodies shrink and shorten. The motionless state in which monogeneans survive unfavorable conditions known as anabiotic or resting stage. When moved from extreme to normal conditions, dactylogyrids can leave this stage, in case the influence of unfavorable factors have not led to irreversible changes in the parasite's organism. But if such changes took place, a transversal constriction is formed on the monogenean body close to the attachment disc, where the disruption of tegument occurs. Thus, appearance of the transversal constriction can be considered a death criterion for monogeneans of the genus Dactylogyrus. It was found that immature monogeneans are more resistant to the effect of extreme temperatures in comparison with egg laying parasites.

[Invasion of fish with leeches (Fam. Piscicolidae) in reservoirs of the Volga river]. / Zarazhennost' ryb piiavkami (Sem. Piscicolidae) v volzhskikh vodokhranilishchakh.

It is shown for the first time that during 50 years of the Rybinsk reservoir's existence the abundance of parasite leeches (Piscicolidae) has increased, and the species composition has become richer. In 70 the leech Caspiobdella fadejewi (Epstein) was registered here as a mass species. This species became a real competitor to Piscicola geometra (L.) inhabiting the Volga river in all times. In early '90s the leech Acipenserobdella volgensis (Zykoff) appeared in the Rybinsk reservoir. Till 1987 this species was not found to the north from the Kuibyschev reservoir. An increase in number of fish leeches and an extension of their specific composition occurred not only in the Rybinsk reservoir but in the other reservoirs of the Volga cascade as well.

[Ectoparasite infection of some fish species in lake Pleshcheev]. / O zarazhennosti éktoparazitami riada vidov ryb oz. Pleshcheevo.

Ectoparasites have been investigated on gills of the ruff, perch, white bream, roach, bream, ide, and European cisco from the Pleshcheevo lake. 13 parasite species were found: Dactylogyrus falcatus, D. distinguendus, D. cornoides, D. cornu, D. sphyrna, D. robustus, D. amphibothrium, Ancyrocephalus paradoxus, Argulus foliaceus, Ergasilus sieboldi, Achtheres percarum, Ancyrocephalus percae, and Rhipidocotyle companula. A reliable negative correlation between the number of monogeneans An. paradoxus and the copepods Ac. percarum on the perch. D. falcatus, the specific monogenean of the bream, was found on the roach. The comparison of the obtained data with those of 1939 has shown the decrease of oxyphilic copepods E. seiboldi, that prove the increasing eutrophication.

[The adaptive reactions of the gill ectoparasites of the bream (Abramis brama) and of the white bream (Blicca bjoerkna) to exposure to an anthropogenic factor in the Ivan'kovo Reservoir]. / Adaptivnye reaktsii zhabernykh éktoparazitov leshcha (Abramis brama) i gustery (Blicca bjoerkna) na vozdeistvie antropogennogo faktora v Ivan'kovskom vodokhranilishche.

Adaptive responses of some gill ectoparasites of the common bream Abramus brama and the white bream Blicca bjoerkna have been studied in five zones of the Ivan'kovo Reservoir: in the region of favorable ecological conditions, in two eutrophic zones and in two areas under the toxic loading. It is found out, that at the response to the pollution the infestation of fishes with most parasite species decreases. The replacement of dominant species is also can be considered as the adaptive response of parasites. It is recorded, that each examined zone with a specific ecological conditions obtains a specific parasite species grouping with a certain composition and abundance of parasite species. The monogeneans of the genus Dactylogyrus express their adaptation to increased temperature by decrease of chitinoid structure size in attachment disc, while the copepods Ergasilus sieboldi react to this factor by faster maturation of egg sacks.

[Skin leiomyomas]. / Leiomiomy kozhi.

Three patients with multiple leiomyomas of the skin were treated with electro-excision techniques. The tumor was hereditary in one of these patients.