[Photolysis of aflatoxin B1 in the presence of pyridine N-oxide]. / Fotoliz aflatoksina B1 v prisutstvii N-okisi piridina.

Aflatoxin B1 (AFB1) photolysis in presence of pyridine N-oxide was studied. It was established that AFB1 ethanol solution irradiated with UV-light lambda = 362 nm demonstrated an increase of the fluorescence as a result of appearance of AFB1 product which was formed by pyridine N-oxide oxygen binding to AFB1 molecules in position 2,3.

[Pigmented formations in the redfish Sebastes mentella]. / Pigmentnye obrazovaniia u okunia-kliuvacha Sebastes mentella.

The study was carried out on 34,960 specimens of redfish out of which 103 individuals were examined histologically. The black spots proved to be superficial (48) and deep melanosis (24). Skin pterinophorosis was revealed in 20 cases. 24 fishes showed benign chromatoblastomas, among them: 14 melanomas, 5 pterinophoromas and 5 pterinomelanophoromas. The tumours occurred only against a background of the spots above 20 cm2 which were observed in 2.4% of fish of the given population. The major part (76.2%) of pigmented lesions did not exceed 5 cm2. 97.6% of spots in females were found between the pectoral and the first dorsal fins, 84% of spots in males--on the head and caudal fin. The pigmented spots in females occurred 2-5 times more often. Genetic factors are, probably, responsible for pigmented neoplasms and lesions in redfish.

[Malignant lymphomas of various histological types in pike from the eastern portion of the Baltic Sea]. / Zlokachestvennye limfomy razlichnykh gistologicheskikh tipov u shchuk vostochnoi chasti Baltiiskogo moria.

Malignant lymphomas have been found in pikes (Esox lucius L.) caught in the eastern part of the Baltic Sea. The frequency of the disease has increased in recent years. Three different histological types of malignant lymphoma are described in 32 pikes: poorly differentiated diffuse lymphocytic lymphoma, mixed (histiocytoid-lymphocytic) diffuse lymphoma and undifferentiated (anisomorphic) diffuse lymphoma.

[Tumors of the gastrointestinal system in the rainbow trout]. / Opukholi zheludochno-kishechnogo trakta u raduzhnoi foreli.

Gastrointestinal tumours occurring in rainbow trout were investigated histologically and virologically. Neoplasms in stomach, medium and posterior intestine mainly in distal parts of these organs were found. Histologically the tumours are benign adenomatous polyps, differentiated adenocarcinomas, poorly differentiated adenocarcinomas, and poorly differentiated or entirely anaplastic adenocarcinomas. The last two types of tumours produced metastases into pancreas, pyloric caeca, and the liver. Virological investigations failed to confirm the presence of any oncoviral particles in these tumours. Aflatoxin analysis of fish foodstuffs gave negative results.

[Microsomal and photochemical oxidation of aflatoxin B1]. / Mikrosomal'noe i fotokhimicheskoe okislenie aflatoksina B1.

The UV irradiation (lambda = 362 nm) of aflatoxin B1 (AfB1) dissolved in water resulted in the formation of an oxidized product. The process was not inhibited by ionol, a routine inhibitor of the radical processes. The oxidized product was not found in the system where AfB1 was metabolized by the 3-methylcholanthrene-activated rat liver microsomes. It is suggested that the product is identical with 2,3-dihydrodiol of AfB1.

[Patterns of distribution of benzo(alpha)pyrene in fishes]. / Nekotorye zakonomernosti raspredeleniia benz(al'fa)pirena v tkaniakh ryb.

The paper presents comparative data on the levels of benzo(a)-pyrene (BP) in the muscular tissue of 326 specimens of various fishes: marine, brackishwater, migratory, semi-migratory and freshwater. The highest level of BP was found in migratory fish. It is probably due to the abundance of fat species among them. Although BP concentration in Estonian waters and in various fishes: is relatively low, there is evidence of fishcancer. Eight out of 60 fishes were found to have cancer. In six out of these eight cases it was microsarcoma of pike.