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Cytochrome P450 (CYP) of chicken and other avian species have been studied primarily with microsomes or characterized by cloning and protein expression. However, the overall existing isoforms in avian CYP1-3 families or dominant isoforms in avian xenobiotic metabolism have not yet been elucidated. In this study, we aimed to clarify and classify all of the existing isoforms of CYP1-3 in avian species using available genome assemblies for chicken, zebra finch, and turkey. Furthermore, we performed qRT-PCR assay to identify dominant CYP genes in chicken liver. Our results suggested that avian xenobiotic-metabolizing CYP genes have undergone unique evolution such as CYP2C and CYP3A genes, which have undergone avian-specific gene duplications. qRT-PCR experiments showed that CYP2C45 was the most highly expressed isoform in chicken liver, while CYP2C23b was the most highly induced gene by phenobarbital. Considering together with the result of further enzymatic characterization, CYP2C45 may have a dominant role in chicken xenobiotic metabolism due to the constitutive high expression levels, while CYP2C23a and CYP2C23b can be greatly induced by chicken xenobiotic receptor (CXR) activators. These findings will provide not only novel insights into avian xenobiotic metabolism, but also a basis for the further characterization of each CYP gene.

19Fish consumption is known to have several health benefits for humans. However, the ww. DDTs were the predominant contaminants (0.9 to 61.9 ng g 1 ww), followed by HCHs. 27The predominance of DDTs may be attributed to their current use in vector control and

Scattering coumarin-derivative rodenticides in broad areas have caused primary-and secondary-poisoning incidents in non-target wild birds. In this study, we compared factors determining warfarin sensitivity between bird species and rats based on vitamin K 2,3-epoxide reductase (VKOR) kinetics, VKOR inhibition by warfarin and warfarin metabolism assays. In VKOR characterization, chickens and ostriches showed significantly lower enzymatic efficiencies than rats (one-sixth and one-third, respectively), suggesting bird species depend more on a non-VKOR vitamin K source. On the other hand, the inhibition constants (K i ) of VKOR for warfarin were significantly different between chickens and ostriches (11.3 ± 2.5 μM and 0.64 ± 0.39 μM, respectively). Interestingly, the ostrich K i was similar to the values for rats (0.28 ± 0.09 μM). The K i results reveal a surprising possibility that VKOR in some bird species are easily inhibited by warfarin. Warfarin metabolism assays also showed a large inter-species difference in bird species. Chickens and ostriches showed higher metabolic activity than that of rats, while mallards and owls showed only a slight ability to metabolize warfarin. In this study, we clarified the wide inter-species difference that exists among birds in xenobiotic metabolism and sensitivity to a rodenticide.

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20The levels and bioaccumulation of organochlorine pesticides (OCPs) and heavy metals 21 were studied in muscle and liver of three fish species, with two trophic levels, from Lake

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Ten cyclic diarylheptanoids (1-10), including three new compounds: myricanone 5-O-alpha-L-arabinofuranosyl-(1-->6)-beta-D-glucopyranoside (7), myricanone 17-O-beta-D-(6'-O-galloyl)-glucopyranoside (8), and 16-methoxy acerogenin B 9-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (10), along with two flavonoids (11, 12), were isolated from the extracts of Myrica rubra (Myricaceae) bark. The structures of new compounds were determined on the basis of spectroscopic methods. On evaluation of compounds 1-12 against the melanogenesis in the B16 melanoma cells, six compounds, 3, 5, 7, 8, 10, and 12, exhibited inhibitory effects with 30-56% reduction of melanin content at 25 microg/mL with no or very weak toxicity to the cells (82-103% of cell viability at 25 microg/mL). In addition, upon evaluation of compounds 1-12 against the scavenging activities of free radicals [against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical], seven compounds, 1, 3, 5, 6, 8, 11, and 12, showed potent scavenging activity [IC(50) 2-21 microM (0.6-7.3 microg/mL)].