Characterization of Alpha-fetoprotein Levels in Three Dolphin Species:
Development of Sensitive Immunoassays for Analysis of the Pregnancy-associated
Variations |
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Authors: | Yuka MORITA Naoshi HIRAMATSU Toshiaki FUJITA Haruna AMANO Etsuko KATSUMATA Kazutoshi ARAI Toshihide IWASAKI Takashi TODO Akihiko HARA |
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Institution: | 1)Graduate School of Fisheries Sciences, Hokkaido University, Hokkaido 041-8611, Japan;2)Faculty of Fisheries Sciences, Hokkaido University, Hokkaido 041-8611, Japan;3)International Marine Biological Research Institute, Kamogawa Sea World, Chiba 296-0041, Japan;4)National Research Institute of Far Sea Fisheries, Fisheries Research Agency, Kanagawa 236-8648, Japan |
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Abstract: | A single radial immunodiffusion (SRID) assay and a chemiluminescent immunoassay (CLIA)
were initially developed for alpha-fetoprotein (AFP) of the striped dolphin. Utilizing
these developed assays, we investigated pregnancy-associated changes in the levels of AFP
in the sera of fetuses and pregnant females of three dolphin species; samples were either
collected from captive individuals or obtained as fishery by-products. The concentrations
of AFP in the fetal serum ranged from 419.0 to 2026.3 μg/ml in the striped dolphin, 12.6
to 1218.7 μg/ml (for an AFP equivalent; eqAFP) in the common bottlenose dolphin and 770.6
to 3129.1 μg eqAFP/ml in the Risso''s dolphin. AFP levels decreased with increased fetal
size in fetuses over 20 cm in length. The concentrations of AFP in sera of pregnant
females ranged from 7.18 to 8068.7 ng/ml in the striped dolphin, 6.6 to 1241.1 ng eqAFP/ml
in the common bottlenose dolphin and 3.4 to 2868.7 ng eqAFP/ml in the Risso''s dolphin. The
levels in most pregnant females were equal to or lower than those found in males and
nonpregnant individuals, although a few pregnant females exhibited extremely high levels
(in the range of hundreds to thousands of nanograms per milliliter). Such high levels of
AFP were not observed during pseudopregnancy. To our knowledge, this is the first report
on basal profiles for serum AFP levels in small odontocetes. The profiles indicated that
AFP may play a significant role during embryonic development, although maternal levels do
not appear to be a diagnostic biomarker for monitoring pregnancy. |
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Keywords: | Alpha-fetoprotein (AFP) Cetaceans Chemiluminescent immunoassay (CLIA) Single radial immunodiffusion (SRID) Striped dolphin |
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