Effects of stress on the zinc concentration in the tissue of head kidney of common carp and it's physiological meaning

• Main Authors: Chien-Lin Liu, 劉建麟
• Other Authors: Sen-Shyong Jeng
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/10094803187492155107

碩士 === 國立臺灣海洋大學 === 食品科學系 === 98 === Common carp (Cyprinue carpio) is a eurythermal fish with an optimum water temperature of 20~27oC. It can still maintain life when water temperature was lower than 4oC. Common carp in anoxia can also tolerate dissolved oxygen down to 1 ppm. Besides, head kidney of the common carp will release hormone cortisol when it was subjected to stress. The effects of cortisol injection, anoxia and cold challenge on the zinc concentration in the head kidney of the common carp were studied. After the injection of cortisol, zinc concentration in the head kidney of the common carp increased from 308 to 618 μg/g fresh tissue. After 3 d of anoxia, it increased from 328 to 1,871 μg/g fresh tissue. After 18 h of cold challenge, it increased from 410 to 657 μg/g fresh tissue. In stress the zinc concentration in the head kidney of common carp increased; when the environment returns to normal state the zinc concentration decreased to the level of normal. These results indicate that zinc concentration in the head kidney of the common carp seems related the stress such as injection of cortisol, anoxia and cold challenge. Subcellular fractionation of the common carp that had been injected with cortisol, anoxia or cold challenge had higher zinc concentration inside the cells of the head kidney. In order to know whether the zinc inside the cell of the head kidney cells was combined with proteins, the nuclei fraction of the head kidney was separated. The nuclei fraction was treated with different concentration of proteinase K. Results indicate that with increase of the enzyme concentration, the release of zinc will increase. When the proteinase K concentration increased to 2.0 mg/ml, the zinc released could reach to ~55%. At the same time, the release of cortisol also increased. These results indicate that the zinc inside the head kidney cell should be bound to protein, and this protein also combined with cortisol. In addition, head kidney nuclei fraction was treated with DNase I (10 unit/ml), then added the proteinase K. It was found the combination of treatment with DNase and proteinase increased the release of the bound zinc. When proteinase K concentration increased to 2.0 mg/ml, the release of zinc was up to ~71%. The above experiments indicate that the protein inside head kidney cell which had zinc and cortisol bound may also combine with DNA. The protein bound with cortisol and zinc might be transcription factor which might promote the RNA polymerase. In this mechanism zinc may play the role to regulate the transcription factor.