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标题：Development of a system for measuring calcitonin in the stingray Dasyatis akajei (a cartilaginous fish): the possible involvement of stingray calcitonin in gonadal development
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作者：Takashi Takagi ; Toshio Sekiguchi ; Yuichi Sasayama 等
期刊名称：International Aquatic Research
印刷版ISSN：2008-6970
出版年度：2019
卷号：11
期号：3
页码：267-276
DOI：10.1007/s40071-019-00236-0
出版社：BioMed Central
摘要：To elucidate the physiological role of calcitonin (CT) in stingrays (cartilaginous fish), an enzyme-linked immunosorbent assay (ELISA) system using a specific antibody against stingray CT has been developed. Synthetic stingray CT was subcutaneously injected into mice four times—once every 2 weeks—together with an adjuvant. We purified the IgG antibody fraction using the protein A affinity chromatography from collected antiserum. Evaluating the antibody titer, we found the antibody’s optimum dilution ratio to be 600 times. Competitive ELISA has been developed using the antibody diluted 600 times. Our antibody did not cross-react with teleost CTs and muscle extraction, but cross-reacted with stingray plasma and the extract of the ultimobranchial gland, the secretary organ of stingray CT. Using this ELISA, we measured the plasma CT level in stingrays and examined its correlation with several mineral concentrations. Plasma CT did not show significant correlation to calcium, magnesium, inorganic phosphorus, sodium, chlorine, or urea, although there was a correlation among the factors involved in osmoregulation, such as sodium, chlorine, and urea. On the other hand, plasma CT was significantly correlated to body weight and length. Furthermore, there was a significant correlation between plasma CT and gonad weight. Since plasma CT was correlated with the weight of liver, which is involved in the synthesis of egg yolk protein, we examined the influence of 17β-estradiol (E₂) on CT secretion. After E₂ injection, the plasma CT level increased significantly. This is the first study to demonstrate that E₂ induced plasma CT secretion in cartilaginous fish.
关键词：Calcitonin ; Sexual maturation ; ELISA ; Stingray ; Cartilaginous fish