萊氏擬烏賊胚胎在高溫緊迫下的氧化代謝研究
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2014
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環境溫度變異會促使變溫動物改變代謝機制，細胞內將因此產生過量的活性氧/氮化物(ROS/RNS)累積造成細胞毒害。本研究運用萊氏擬烏賊(Sepioteuthis lessoniana)胚胎探討高溫環境下頭足類動物的細胞代謝策略。根據胚胎耗氧與排氨實驗發現：頭足類胚胎在發育初期的整體代謝容易受到高溫環境影響而提升，故本實驗選擇早期胚胎(stage 25)進行高溫緊迫研究。在高溫緊迫下，細胞中ROS/RNS濃度沒有顯著變異，而抗氧化因子(CAT, SOD, HRP)，抗逆境基因(HSP70, HSP90)與細胞色素c氧化酶(Cox I)的基因表現相均有上升趨勢。進一步發現低氧誘導因子(HIF-1)與鈉鉀幫浦(NKA)蛋白質表現量與高溫誘導的適應性能量轉移(adaptive metabolic shift)機制有關。因此我們推論：高溫緊迫下的萊氏擬烏賊胚胎可以藉由增加並調整呼吸代謝與氨基酸代謝的機制獲得能量，而細胞內亦會啟動有效的抗氧化機制抵禦ROS與RNS的累積。
關鍵字：高溫緊迫、萊氏擬烏賊、氧化代謝
Under temperature perturbations, metabolic strategies of ectothermic vertebrates would be modified and further increase the cellular reactive oxygen/nitrogen species (ROS/RNS) formations. Previous studies indicated that excess ROS/RNS accumulation would cause cytotoxicity. However in cephalopods, the cellular and physiological mechanisms behind metabolic adaptation under temperature perturbations is still an open question. In this study, we use squid (S. lessoniana) embryos as a cephalopod model to investigate the antioxidant mechanisms and further metabolic modifications under hyperthermic environment. According to oxygen consumption rate and ammonium excretion rate studies in squid embryos, 25-stage squid embryos were sensitive to ambient hyperthermic stress and further selected for following experiments. Under hyperthermic conditions, intracellular ROS/RNS contents were not obviously changed. Transcripts expressions of cytochrome c oxidase I (Cox I), anti-oxidation molecules (CAT, SOD, HRP) and stress-resistant genes (HSP70, HSP90) were up-regulated under hyperthermic stress. Moreover protein expressions of hypoxia-inducible factor 1-alpha (HIF-1) and Na+-K+-ATPase (NKA) are close related to cellular adaptive metabolic shift in hypothermic conditions. In conclusion, intact metabolic rate increment in squid embryos under hyperthermic stress would further induce adaptive metabolism shift for proper physiological functions and avoiding ROS/RNS accumulation. keywords：hyperthermic environment、Sepioteuthis lessoniana、oxidative metabolism
Under temperature perturbations, metabolic strategies of ectothermic vertebrates would be modified and further increase the cellular reactive oxygen/nitrogen species (ROS/RNS) formations. Previous studies indicated that excess ROS/RNS accumulation would cause cytotoxicity. However in cephalopods, the cellular and physiological mechanisms behind metabolic adaptation under temperature perturbations is still an open question. In this study, we use squid (S. lessoniana) embryos as a cephalopod model to investigate the antioxidant mechanisms and further metabolic modifications under hyperthermic environment. According to oxygen consumption rate and ammonium excretion rate studies in squid embryos, 25-stage squid embryos were sensitive to ambient hyperthermic stress and further selected for following experiments. Under hyperthermic conditions, intracellular ROS/RNS contents were not obviously changed. Transcripts expressions of cytochrome c oxidase I (Cox I), anti-oxidation molecules (CAT, SOD, HRP) and stress-resistant genes (HSP70, HSP90) were up-regulated under hyperthermic stress. Moreover protein expressions of hypoxia-inducible factor 1-alpha (HIF-1) and Na+-K+-ATPase (NKA) are close related to cellular adaptive metabolic shift in hypothermic conditions. In conclusion, intact metabolic rate increment in squid embryos under hyperthermic stress would further induce adaptive metabolism shift for proper physiological functions and avoiding ROS/RNS accumulation. keywords：hyperthermic environment、Sepioteuthis lessoniana、oxidative metabolism
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萊氏擬烏賊, 氧化代謝, 高溫緊迫, Sepioteuthis lessoniana, oxidative metabolism, hyperthermic environment