Spatial and temporal variation of PCBs and organochlorine pesticides in the Antarctic minke whales, Balaenoptera bonaerensis, in the period 1987-2005.

Concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and chlordane compounds (CHLs) were determined in the blubber of males (20-25 years old) of Antarctic minke whales, Balaenoptera bonaerensis, from the International Whaling Commission (IWC) management Areas IV (70°-130°E) and V (130°E-170°W), south 60°S. The ranges of concentrations (ng g(-1) lipid wt.) for each compound were, PCBs: 7.7-89; DDTs: 29-340; HCHs: 0.20-4.3; HCB: 75-430; CHLs: 10-120, which were much lower than those in common minke whales, Balaenoptera acutorostrata, from the northern hemisphere. The levels of PCBs, HCHs, HCB and CHLs in Area IV were significantly higher than those in Area V, while the levels of DDTs in both areas were similar. For comparing the fate among four pesticides in the Antarctic Ocean avoiding the effect of variance due to food intake, the ratios of the pesticides to PCBs, which has an extremely high chemical stability and environmental persistence, were examined. The HCHs/PCBs ratio decreased by a factor of about 20 in a span of 16 years in both Areas IV and V, while temporal trends of DDTs/PCBs, HCB/PCBs and CHLs/PCBs ratios were not observed. These results indicate that PCBs, DDTs, HCB and CHLs levels did not vary or slightly decreased in Areas IV and V during the study period. However HCHs levels clearly decreased. Spatial differences seems to be related to differences in food intake among whales, and temporal differences seems to be related to the length stay of OCs in the Antarctic Ocean.

Molecular evidence of new variant Brucella in North Pacific common minke whales.

Brucella, a causative agent of brucellosis, has been isolated recently from a variety of marine mammals. The molecular analysis of marine mammalian Brucella strains, without manifest pathology of brucellosis in the eastern North Atlantic, showed that they are distinct from terrestrial Brucella species. Previously, we reported abnormal gonads in common minke whales (Balaenoptera acutorostrata) in the western North Pacific and suggested the presence of Brucella infection in the whales in pathology and serology studies. In the present study, using polymerase chain reaction (PCR), Brucella was detected in granular testes of the whales showing caseation or calcification. The insertion of an IS711 transposable element specific for marine mammal isolates as well as a seal isolate-specific DNA fragment were also found. Molecular characterization of Brucella based on sequence analysis of the PCR products amplified from the outer membrane protein (omp) 2 gene showed that the Brucella from North Pacific common minke whales was different from terrestrial and North Atlantic marine mammal Brucella strains. The North Pacific Brucella showed the highest similarity to North Atlantic seal strains among the known Brucella strains.

Pathological and serological evidence of Brucella-infection in baleen whales (Mysticeti) in the western North Pacific.

Abnormal testes and uterus were observed in 13 males (33%) and one female (3%) out of 40 common minke whales (Balaenoptera acutorostrata) in the western North Pacific. Similar lesions were found in testis and ovary, respectively, in one male (2%) and female (2%) out of 43 Bryde's whales (Balaenoptera edeni) in the western North Pacific. Grossly, granular lesions with caseation and calcification were main pathological signs, and they were restricted to reproductive organs of mature whales. Chronic purulent or granulomatous orchitis was observed by microscopic analysis. Antibodies to Brucella species were detected in the serum samples of 15/40 (38%) of common minke whales and 4/43 (9%) of Bryde's whales. Neither pathological nor serological change was found in the examined sperm whales (Physeter macrocephalus) in the western North Pacific and Antarctic minke whales (Balaenoptera bonaerensis). These results strongly suggest that Brucella infection was involved in two species of baleen whales (Mysticeti) in the North Pacific.

Chimeric structure of omp2 of Brucella from Pacific common minke whales (Balaenoptera acutorostrata).

In the Pacific common minke whale (Balaenoptera acutorostrata ), a new variant of Brucella has been detected using the polymerase chain reaction. Detailed analysis of the porin protein genes, omp2a and omp2b from the whale Brucella showed that these two genes have some motifs in common with Atlantic marine strains in the 5'-terminal one-third region. On the other hand, the nucleotide sequences in the 3'-terminal two-thirds region of the two genes were almost identical to the respective genes of terrestrial strains. Thus, Pacific whale Brucella omp2 genes are chimeras between marine and terrestrial strains.