Overwinter body condition, mortality and parasite infection in two size classes of 0+ year juvenile European bitterling Rhodeus amarus.

Body condition and parasite abundance were examined in two size classes of European bitterling Rhodeus amarus during the first overwintering period in two seasons (2007-2008 and 2009-2010). Body condition of large fish did not change during winter, and increased significantly in March. From November to February, small fish showed a decreasing trend in condition. Despite a significant increase in March condition of small fish only reached the same level as before winter. Total parasite abundance increased significantly in winter in both fish size classes, reflecting a seasonal increase in monogenean infection. Large fish were parasitized significantly more than small fish during winter, but only in small fish was a negative correlation between parasite infection and condition found and a significant decrease in parasite abundance recorded after wintering, indicating mortality of heavily infected individuals with low condition during the winter. A trend for higher overwinter mortality in small fish was found under semi-experimental conditions. The decrease in condition during the winter period in small fish may reflect faster energy depletion generally expected in smaller individuals. The results indicate that parasite infection may contribute to the overwinter mortality of 0+ year R. amarus, with a stronger effect in smaller individuals.

Ability of bacterial biphenyl dioxygenases from Burkholderia sp. LB400 and Comamonas testosteroni B-356 to catalyse oxygenation of ortho-hydroxychlorobiphenyls formed from PCBs by plants.

Capacity of enzymes of the biphenyl/chlorobiphenyl pathway, especially biphenyl dioxygenase (BPDO) of two polychlorinated biphenyls (PCB) degrading bacteria, Burkholderia sp. LB400 and Comamonas testosteroni B-356, to metabolize ortho-substituted hydroxybiphenyls was tested.,These compounds found among plant products of PCB metabolism, are carrying chlorine atoms on the hydroxyl-substituted ring. The abilities of His-tagged purified LB400 and B-356 BPDOs to catalyze the oxygenation of 2-hydroxy-3-chlorobiphenyl, 2-hydroxy-5-chlorobiphenyl and 2-hydroxy-3,5-dichlorobiphenyl were compared. Both enzyme preparations catalyzed the hydroxylation of the three chloro-hydroxybiphenyls on the non-substituted ring. Neither LB400 BPDO nor B-356 BPDO oxygenated the substituted ring of the ortho-hydroxylated biphenyl. The fact that metabolites generated by both enzymes were identical for all three hydroxychlorobiphenyls tested; exclude any other mode of attack of these compounds by LB400 BPDOs than the ortho-meta oxygenation.

9-[2-(phosphonomethoxy)ethyl]-2,6-diaminopurine (PMEDAP)--a potential drug against hematological malignancies--induces apoptosis.

Antitumor activity of the acyclic nucleotide analogs PMEDAP, PMEA, and PMEG was studied on a model of a spontaneous T-cell lymphoma in inbred SD/cub rats. Significant therapeutic effects were recorded after a treatment with 16 daily doses of PMEDAP at 5 mg/kg applied to the vicinity of the growing lymphoma. Identical administration of PMEA, or PMEG at a daily dose of 0.1 mg/kg did not affect the survival of lymphoma-bearing animals compared with untreated controls. A decrease in the lymphoma weight during PMEDAP administration was accompanied by the suppression of mitotic activity in neoplastic cells and increased chromatin condensation as witnessed by karyological examinations. Electron-microscopy showed the morphology of apoptotic cells (shrunken cells with condensed chromatin, apoptotic bodies) in lymphoma cell suspensions. An increase of nuclear DNA fragmentation was found during PMEDAP administration compared with spontaneous DNA fragmentation of untreated control lymphomas. These results indicate that PMEDAP application induces apoptosis in in vivo growing lymphomas. The antitumor effect of PMEDAP lasts only during the administration of the drug. After its cessation progression of neoplasia was reestablished.