| Abstract: | 清白招潮蟹是一種廣泛分佈於海岸潮間帶的半陸生性螃蟹，由於每日潮汐的漲退，生存環境鹽度的變化相當的大。雖然過去文獻中指出Na+, K+ -ATPase及carbonic anhydrase（CA）同為參與離子調節的重要酵素，但在蟹類相關研究中並未發現它們被同時探討的文獻。從前人的報告中發現，在不同鹽度處理下，螃蟹鰓上Na+, K+ -ATPase活性在低鹽度處理下表現較高，且後半部鰓比前半部鰓高的趨勢。在CA部分，在不同鹽度處理下，各對鰓間CA活性表現趨勢有種別性而呈現不一致的情形。在本實驗中，希望討論清白招潮蟹不同對鰓間活性表現的趨勢。實驗設計首先進行5、25、45 ‰鹽度馴養試驗，測量滲透壓、鰓間Na+, K+ -ATPase與CA活性的變化，並使用western blotting方法，比較鰓間Na+, K+ -ATPase與CA含量的變化。由體液滲透壓變化的結果指出，清白招潮蟹屬於hyper-hypo osmoregulator。在不同鹽度處理下，清白招潮蟹後半部鰓的Na+, K+ -ATPase及CA活性表現較前鰓高，且低鹽度處理顯著比高鹽度處理表現高。Western blotting結果同樣顯示在不同鹽度馴養下後鰓表現比前鰓高。由CA活性在45 ‰處理下，各對鰓活性表現顯著比25 ‰處理組高的現象，可能暗示在高鹽環境下CA所扮演離子調節的角色比Na+, K+ -ATPase更為重要。
Uca lactea is a semi-terrestrial crab and widely distributes along the west coast of Taiwan. It lives in intertidal areas and is subjected to large daily and seasonal changes in salinity. Previous literature indicated that not only Na+, K+-ATPase but also carbonic anhydrase (CA) are important in osmoregulation. However, these two enzymes have never been studied simultaneously for the osmoregulation of brachyuran crabs. From previous studies, the CA activity in different pairs of gills was species-specific. No significant difference among gill CA activity was found in one crab species with high salinity treatment while a significantly higher CA activity in the posterior gills in a Uca species was reported in another report. In my study, I examined the variation of these two enzymes in Uca lactea. The experiment started with salinity acclimation of 5, 25, 45 ‰ and osmolality, Na+, K+-ATPase and CA activity and western blotting were examined. From osmolality results, Uca lactea is a hyper-hypo osmoregulator. Both Na+, K+-ATPase and CA activity were higher in diluted seawater and in posterior gills. The results from western blotting had a similar pattern in that Na+, K+-ATPase and CA were higher in posterior gills. The CA activity in Uca lactea was higher in 45 ‰ than in 25 ‰, suggesting that the CA may be more important than Na+, K+-ATPase in osmoregulation in concentrated seawater. |
