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標題: | 日本鰻Anguilla japonica礦物性皮質素受體(minerolocorticoid receptor)參與低張環境離子調節 Mineralocorticoid receptor involves in ionoregulation in Japanese eel (Anguilla japonica) in hypotonic environment |
作者: | Yau-chung Hu 胡耀中 |
指導教授: | 羅秀婉 |
關鍵字: | 日本鰻,礦物性皮質素受體,11β羥基類固醇脫氫酶,2型,鈉鉀幫浦,粒線體富含細胞,安體舒通, Anguilla japonica,mineralocorticoid receptor (MR),11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2),mitochondria-rich cell (MRC),spironolactone, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 日本鰻(Anguilla japonica)在洄游的生活史中需要一精巧的荷爾蒙系統調節體內離子平衡以適應不同的鹽度,目前可體松(cortisol)被認為在魚類同時具有葡萄醣皮質素(glucocorticoid)和礦物性皮質素(mineralocorticoid)功能的主要皮質醇(corticosteroid),而在哺乳類中有專一的礦物性皮質素受體(mineralocorticoid receptor)維持體內離子恆定,並有酵素11β羥基類固醇脫氫酶2型(11β-hydroxysteroid dehydrogenase-type 2)保護其不被可體松接上而失去功能,礦物性皮質素受體的演化最早被認為出現在軟骨魚中,極為可能在硬骨魚中如哺乳類的功能就已存在。在低張離子環境下,硬骨魚利用具高活性鈉鉀幫浦(Na+, K+-ATPase)的離子吸收粒線體富含細胞(mitochondria-rich cell)來維持滲透壓,本篇作者從日本鰻得到的礦物性皮質素受體和已發表的鰻魚11β羥基類固醇脫氫酶2型同源酵素e11β-HSDsf之互補DNA (cDNA)序列,將日本鰻轉移至蒸餾水中使吸收離子的粒線體富含細胞出現在鰓薄板上,以證明魚類礦物性皮質素受體參與離子的吸收,在蒸餾水轉移實驗中,粒線體富含細胞於48小時大量增生至鰓薄板上而在去離子蒸餾水轉移的實驗中,粒線體富含細胞於24小時便佈滿整個鰓薄板,更進一步利用絕對定量的RT-qPCR發現鰓、腸和腎中礦物性皮質素受體和e11β-HSDsf信使RNA (mRNA)於蒸餾水轉移中表現隨時間具有一致性的趨勢,並且e11β-HSDsf的信使RNA數量皆比礦物性皮質素受體多,表示e11β-HSDsf具有保護礦物性皮質素受體的可能。在礦物性皮質素原位雜和的結果也顯示其位於粒線體富含細胞中,進一步觀察礦物性皮質素受體和鈉鉀幫浦活性在時間變化上的關係以及在鰓薄板出現粒線體富含細胞的情況下施打礦物性皮質素受體擷抗劑安體舒通(spironolactone),鈉鉀幫浦活性降至約略淡水的活性。因此,本篇認為日本鰻在低張環境下礦物性皮質素受體會藉由e11β-HSDsf的保護來進行離子吸收。 Japanese eels (Anguilla japonica) are catadromous with a delicate hormonal system to maintain normal ionic levels under different salinity. Cortisol is the major corticosteroid in teleost and is considered to be a dual regulator as glucocorticoid and mineralocorticoid. On the other hand, mineralocorticoid receptor (MR) function of ion-retention and its protection from excess cortisol binding by 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) are well known in mammals. Since the ancestral MR appeared in cartilaginous fish, the MR may be functional in teleosts. In ion deficient environment, teleosts maintain their osmolarity by ion-absorptive mitochondria-rich cells (MRCs) with highly-regulated Na+, K+-ATPase (NKA) activity. The cDNA sequence of eel MR has been cloned in this thesis and 11β-HSD2 homolog, e11β-HSDsf was retrived from database. To testify the ion-retention role of MR, I induced proliferation of ion-absorptive MRCs in the gill of Japanese eel, Anguilla japonica under distilled water (DW). In DW transfer, lamellar MRCs distributed abundantly after 48 hours and lamellar MRCs cells distributed on the whole lamella after 24 hours in the DDW transfer. By absolute quantification of RT-qPCR, the MR and e11β-HSDsf mRNA levels were up-regulated in same patterns during time course in DW in the gill, intestine and kidney. There were also more copy numbers of e11β-HSDsf than copy numbers of MR. It is possible that e11β-HSDsf protects MR in eels. The result of in situ hybridization showed that the mRNA of MR localized in the MRCs. NKA activity is an indicator of osmoregulation in both fish and mammals. The relations between MR and NKA activity was investigated by time-course and antagonist treatment. NKA activity decrease to freshwater (FW) level in MR antagonist, spironolactone treatment under the presence of lamellar MRCs. This study suggest the protection of MR by e11β-HSDsf and establish the MR function in ion-retention under hypotonic environment in Japanese eels. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/29996 |
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顯示於系所單位: | 漁業科學研究所 |
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