海洋酸化對黑點青鱂魚生理恆定及表觀遺傳修飾之影響評估

Effects of ocean acidification on physiological homeostasis and epigenetic modification in Oryzias melastigma

劉姿延(Liu Tzu-Yen)

指導教授 ： 林豊益 ； 曾庸哲

國立臺灣師範大學/理學院/生命科學系/碩士(2017年)

https://doi.org/10.6345/NTNU202202342

摘要

['工業革命後人類的現代化活動造成大氣中二氧化碳濃度逐漸上升，當二氧化碳溶入海水會解離出碳酸根離子與氫離子，造成海水的 pH 值下降，這個現象稱為「海洋酸化」。許多研究指出：海洋酸化會影響海洋生物的存活率、 多樣性及生理恆定，因此被認為是個全球性的環境議題。
本實驗選用海水青鱂魚(Oryzias melastigma)作為長期高碳酸馴養試驗的模式魚種，實驗結果有別於過去在廣鹽性日本青鱂魚的發現，其胚胎並無發育遲緩的現象，而酸化處理後的胚胎個體及成魚的鰓與腸中之酸鹼離子調控蛋白群(AE1a、 NBCa 及 NHE2)基因表現量均會顯著上升。此外，在酸化海水發育成熟的個體卵巢中， AE1a 的啟動子甲基化程度會顯著提升。而酸化個體產下之 F1 子代酸鹼離子調控蛋白群的啟動子並未有顯著甲基化的趨勢，其基因表現量與排氫離子能力仍保持顯著提升。綜合以上結果我們推論：硬骨魚母體可能透過表觀遺傳的機制將生理適應訊息傳遞給子代，子代為了適應酸化環境會進而修飾啟動子的甲基化程度，並且持續增強酸鹼調節的能力；此外， AE1a、 NBCa 和 NHE2 為硬骨魚類調控酸鹼平衡之主要蛋白，並且能夠作為觀察表觀遺傳現象之有效生物標記。']

關鍵字

海洋酸化 ； 海水青鱂魚 ； 酸鹼調控 ； 表觀遺傳

並列摘要

['Ocean acidification (OA) has been recently recognized as an emerging global stressor, potentially affecting ecosystems’ biodiversity, concordance and functions. Studies regarding the effects of OA on marine organisms have been primarily conducted in laboratory; nevertheless, long-term physiological consequences regarding OA perturbations is still an unexplored issue. In this study, we further applied India medaka (Oryzias melastigma) into CO2-induced hypercapnia challenges. Growth retardation in this marine species is not as significant as previous found in euryhaline Japanese medaka (Oryzias latipes). Moreover, transcripts levels of anion exchanger 1a (AE1a), Na+/HCO3- exchanger a (NBCa) and Na+/H+-exchanger 2 (NHE2) were up-regulated in larvae as well as in adult gills/intestine under OA perturbation. And the methylation level in AE1a promoter was significantly increased in parental ovary of CO2-treated group. However, on one hand, methylation levels of those promoters in the OA-treated F1 offspring were not changed. On the other hands, transcripts levels of acid-base regulators and the H+ secretion ability were kept on upregulated in OA-treated F1 offspring. Based on above results, we inferred that the parent may pass the genetic messages from the primary generation with epigenetic modifications; therefore, their progeny might be endowed with possible capacities to cope with OA perturbations. In addition, AE1a, NBCa and NHE2 can effectively maintain intact homeostasis and be used as markers of epigenetic memory for teleosts to cope with OA stress.']

並列關鍵字

ocean acidification ； marine medaka ； acid-base regulation ； epigentic

參考文獻

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