- 學位論文
蚯蚓經紫外線B照射後體內氧化壓力調控之研究
The Study of UVB Induced Oxidative Stress in Earthworms
摘要
陽光中紫外線B的照射會對地表生物造成很嚴重的傷害，生物們大多利用體表色素、黏液或是其他系統來阻擋及修復紫外線造成的傷害，蚯蚓大部分都是生活在地下，因此牠們被認為對於紫外線的傷害非常敏感，不過之前的研究指出，不同的蚯蚓對紫外線B有不同的耐受性，在這個研究中，我們想要試著找出造成這個現象的原因。Pontoscolex corethrurus是一種對紫外線B耐受性極強的蚯蚓，但是牠體表的色素或黏液沒有吸收紫外線B的功能，因此我們認為P. corethrurus防禦紫外線的機制或許是牠們體內的抗氧化系統。經紫外線B照射後，P. corethrurus體內的過氧化氫濃度會有顯著的增加，但是在60分鐘內會降回基礎值，而抗氧化酵素活性(catalase和superoxide dismutase)也會在處理後三十分鐘顯著提升，若是以catalase抑制劑抑制經紫外線照射後的P. corethrurus的體內catalase活性，P. corethrurus會有提早死亡的情形出現。而對紫外線B較敏感的蚯蚓Eisenia andrei被照射紫外線B之後，氧化壓力顯著得在30分鐘內顯著提升，而且到60分鐘時依然會有上升的趨勢，不過抗氧化酵素活性則沒有顯著變化。為了確定抗氧化和防止紫外線傷害的關係，我們將紫外線B處理過的E. andrei培養在外加抗氧化劑(薑黃素或EUK-134等)的環境，結果顯示外加的抗氧化劑可以有效的降低紫外線B照射造成的個體死亡。因此我們認為，P. corethrurus之所以能夠對紫外線有較高耐性的原因是由於他們的抗氧化酵素系統，抗氧化酵素系統的快速反應可以在短時間內消除掉紫外線B造成的氧化壓力，進而消除或是減少紫外線B造成的傷害。
並列摘要
UVB is harmful to most organisms in the earth. Some animals evolutionally use pigment, mucus or antioxidant to reduce the damage caused by UVB radiation. Earthworms live underground and they have known to be quite sensitive to UVB, but different species of earthworms have different tolerance to UVB. The goal of this study was to find out the possible mechanisms that provide different tolerance for different species of earthworms to avoid UVB damage. Pontoscolex corethrurus can resist high dose of UVB but its mucus has no UVB absorbing function. So the antioxidant in earthworm might be the reasonable mechinisms. The concentration of hydrogen peroxide in P. corethrurus was significantly increased after UVB treatment in 30 minutes, and it decreased back to control in 60 minutes. The activities of catalase and superoxide dismutase (SOD) also had a significant increase in 30 minutes after UVB exposure. When the catalase activity was inhibited by catalase inhibitor, the moratlity of the UVB-treated P. corethrurus was increased. The other kind of earthworm (Eisenia andrei) had a high mortality after UVB irradiation, and the concentration of hydrogen peroxide had significant increase in 30 minutes and had a trend of increasing in 60 minutes. But the activities of antioxidative enzymes didn’t have significant change in an hour after UVB exposure. On the other hand, when the UVB-treated E. andrei incubated with antioxidants, such as curcumin and EUK-134, the additional antioxidants could reduce the mortality caused by UVB. So those results suggested that the quick response of antioxidative enzymatics system in P. corethrurus could handle the oxidative stress caused by UVB in a short time, and quickly remove the oxidative stress in the tissue.