碩士 / 東海大學 / 生命科學系 / 96 / For those studies on the physiological adaptation of crabs, the gill is the main organ of the gas exchange, ion regulation, and ammonia excretion functions. A detailed investigation on the structures and functions of crab gills is crucial for the discussion of environmental physiology of the crabs. In the context of ion regulation, Na+, K+-ATPase (NKA) and V-type H+-ATPase (HA) are important for maintaining an ion gradient between the body and the external environment, and the activities of both enzymes are energy consuming. In general, NKA is distributed in the basolateral membranes of gill epithelia and provides the driving force for ion flux. In fresh water, crabs use apically located HA to pump H+ ion out of the cell, creating an higher electrogenic difference across the membrane than the basolaterally located NKA created. This powers further transport of ions. In our laboratory, we conducted a survey on 13 species of crabs and our results supported the hypothesis that the apical distribution of HA is important for freshwater adaptation. Until now, most discussions on osmoregulatory mechanisms are based on marine crabs, but very few were on freshwater crabs. In my study, by examining the structures of gills of the freshwater crab Candidiopotamon rathbunae, I intended to clarify debate of structural specialization of gill epithelia of freshwater crabs. My results indicated that C. rathbunae has nine pairs of gills and the marginal canals of the lamellae near the efferent side and the middle of marginal canals are swollen. There are two rows of sharp spikes underneath the efferent side and knobs on the surface of the afferent vessels. Among the nine pairs of gills, the epithelia from the first, second and the fourth to sixth gills are thicker than those from the seventh to ninth gills, suggesting different physiological functions. The NKA activities of the fourth, fifth, and sixth pairs of gills are higher than those of other gills. On the first day after transferal to deionized water, NKA activity of the second and the fourth to seventh pairs of gills increased. By day 7, the activities of the second and the fourth to seventh pairs of gills decreased. The results indicated that the fourth to sixth pairs of gills are the ion-regulatory gills. The HA activities of the fifth and ninth gills did not differ significantly between the freshwater treatments and the fourth day in deionized water. The proteins of both NKA and HA did not differ significantly among days after transferal. It is the increase in the NKA activities of proteins, but not in the abundance, that would lead to the rise of the ion exchange efficiency. My results were different from the previous studies in respect to the anterior gills being for gas exchanger and the posterior ones for ion regulation. The relative importance of HA in ionoregulation deserves further investigation. Since only cell membrane located HA is involved in ion uptake, I need to clarify the location of the HA. In the second part of my study, by applying immuno-histochemical staining and immuno-gold labeling, both NKA and HA were found in basolateral membrane while there was a few HA in the apical membrane. The other two ion-uptake membrane proteins were also located by immuno-fluorescence staining and only basolateral Na+/K+/2Cl- cotransporter and Na+/H+ exchanger in the apical membrane were found in the gill epithelia. The Na+/H+ exchanger in the basolateral membrane were only found in the pillar cell. Using C. rathbunae as the study subject, this is the first study to describe that the anterior gills of freshwater crabs is for ion regulation, and the posterior gills is for gas exchange. Gill NKA is the driving forces for ion transport. More investigation is needed on the basolaterally located HA before its function, possibly acid-base balance, can be concluded.
| Identifer | oai:union.ndltd.org:TW/096THU00112009 |
| Date | January 2008 |
| Creators | Tzu Ping Tseng, 曾姿萍 |
| Contributors | Hui Chen Lin, 林惠真 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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