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標題: | 虱目魚與草魚碳水化合物代謝酵素之溫度補償效應 Quantitative thermal compensation in carbohydrate metabolic enzymes of milkfish, Chanos chanos, and grass carp, Ctenopharyngodon idella |
作者: | 胡智傑 |
出版年 : | 1997 |
學位: | 碩士 |
摘要: | 虱目魚為我國主要養殖經濟魚種,屬於熱帶性魚類,適於高溫下養殖,然而牠的耐寒性不佳,每年冬季寒流來襲之際常造成大量死亡,對產業的損失相當嚴重,藉由虱目魚在低溫下壓迫生理反應之瞭解,並與耐寒性佳的草魚比較,期能增進虱目魚耐寒性。本研究重點就能量代謝生理之觀點,探討不同馴化溫度下生理調適變化。 馴化於不同水溫環境中為期四週,草魚(5℃及 15℃)及虱目魚(15℃及 35℃)與馴養在25℃水溫下肝臟與白肌組織中參與碳水化合物代謝途徑酵素,包括lactate dehydrogenase (LDH), pyruvate kinase (PK), citrate synthase (CS), glucose-6-phosphate dehydrogenase (G6PDH), malate dehydrogenase (MDH), pyruvate carboxylase (PC), fructose-l, 6-bisphosphatase (FBPase)及phosphorylase a (PH α),加以比較發現碳水化合物代謝途徑的變動,與馴化的溫度及馴化時間有關。不同程度的低溫環境在相同的組織中會引發不同的代謝途徑,且與馴化持續的時間有關。 草魚馴養在低溫下肝臟組織的碳水化合物代謝途徑增加幅度,於馴化初期以五碳醣代謝(G6PDH)為主,肝臟組織中G6PDH的活性變化在馴化二週時,5℃組與15℃組都有一極高的比值出現,分別為8.82、27.62,於5℃組及15℃組其增幅佔了整個肝臟組織碳水化合物代謝途徑增幅的50%及73%,馴化末期以無氧代謝(LDH)及醣質新生(FBPase)為主。然而虱目魚在低溫環境中,肝臟組織代謝途徑比重的變化與草魚不同,馴化一週時,LDH與FBPase的增幅比重只略高於其他的代謝途徑。高溫馴化下,虱目魚肝臟中的碳水化合物代謝途程,於馴養一週時G6PDH增幅佔了21%,二週時增加有氧代謝(CS)活性,至馴化四週則以進行肝醣分解(PH α)為主。G6PDH活性最高出現在馴養於高溫環境下,比值為2.63,增加的幅度僅為草魚的十分之一。 草魚低溫馴化下白肌組織的代謝途徑,以LDH及FBPase為主,但增幅皆低於肝臟中的變化量,馴養於5℃水溫中,FBPase活性增加的比例高於LDH,15℃組則為LDH增幅高於FBPase,且有氧代謝途徑增加其比重。低溫馴養下,虱目魚白肌組織中的代謝途徑,以分解肝醣與進行有氧代謝為主。馴化在高溫環境中,以CS及醣解代謝(PK)的代謝途徑增加的情形較明顯,分解肝醣的途徑雖也有增加的現象,然而增幅則不及低溫組的明顯。 Milkfish, Chanos chanos, an economically important cultured species in Taiwan, are sutiable for culture in the warm season. Mass mortality of these species have often been experienced by cold kill and resulted in a disastrous loss to the aquaculture industry. This study is aimed to comprehand physiological changes in energy metabolism of milkfish under varying acclimation temperatures and the results were further compared with the cold-tolerant grass carp, Ctenopharyngodon idella, in order to understand the possible causes of cold intolerance of milkfish. The acclimation temperatues of 15℃ and 5℃ for grass carp and 15℃ and 35℃ for milkfish were maintained for 4 weeks period, and the acclimation temperatue of 25℃ was used as reference for both species. The activities of enzymes involved in carbohydrate metabolism in hepatic and muscular tissues were assayed at predetermined time intervals. Included are lactate dehydrogenase(LDH), pyruvate kinase(PK), citrate synthase(CS), glucose-6-phosphate dehydrogenase(G6PDH), malate dehydrogenase(MDH), pyruvate carboxylase(PC), fructose-1,6-bisphosphatase(FBPase) and phosphorylase a(PH a). The pentose shunt pathway indicated by G6PDH activities in the liver was dominant in the eraly phase of cold temperature acclimation in grass carp. The relative G6PDH activities in liver peaked at 8.82 and 27.62 respectively under 5℃ and 15℃ for 2 weeks acclimation, constituted to 50% and 73% of total enzyme activities monitored. The metabolism pathway was shown to shift towards anaerobic and glycogenesis, indicated respectively by LDH and FBPase activities in the later phase of the acclimation. In milkfish, the relative importance of carbohydrate metabolic pathways in the hepatic tissues were found different from those in grass carp, in which, only slight increases in LDH and FBPase activities were noticed at the end of first week acclimation. Under the high temperature acclimation at 35℃, the aerobic metabolim and glycogenolysis were considered to be major pathways of carbohydrate metabolism in the liver of milkfish. G6PDH was found most active in one-week acclimation, constituted to 21% of total enzyme activities, while CS and PH a were shown to be dominant enzymes at 2 weeks and 4 weeks acclimation, respectively. The maximun G6PDH activities measured at 2.63 in relative activity was detected under high temperature, but the degree of increase was only up to one-tenth of the activities in grass carps. The LDH and FBPase activities were found dominant in the carbohydrate metabolism in the muscular tissues of grass carp under cold temperature acclimation. The increase in LDH activities was notably higher than those in the liver of same species, but the extent of FBPase activity increase was much less than that in the liver. In the meantime, aerobic metabolism became important in the cold acclimation. In milkfish, the activites of phosphorylase a, CS and PK were all increased. This observation suggested that the glycogenolysis and aerobic metabolism played important roles under the cold temperature acclimation. Similar trends of enzyme activity changes were also noticed under the high temperature acclimation, but the extent of activity changes was shown to be much less. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/76322 |
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顯示於系所單位: | 漁業科學研究所 |
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