Distribution of Carbonic Anhydrase in Digestive Tract of Pond Loach (Misgurnus anguilicaudatus)

Abstract

ABSTRACT. Carbonic anhydrase (CA) family is discovered in various species including mammals, avians and even plants, but it is rarely reported in fishes. Ten Pond Loaches were used in this study. The results indicated that no evidence of distribution of CA in esophagus. Nonetheless CA was found in the mucosal epithelium of stomach and in the villous epithelium of intestine demonstrated histochemically by the numerous black sedimentation of cobaltous sulfide (CoS) in these areas. In addition, black sedimentations of CoS were also found in all the vascular endothelium examined and red blood cells of digestive tract. The distribution of CA in Pond loach was more closely resemble amphibians than to other species, suggesting evolutional adaptation for Pond loach in aquatic environments. KEY WORDS: carbonic anhydrase, digestive tract, pond loach.

Mechanisms of transepithelial ammonia excretion and luminal alkalinization in the gut of an intestinal air-breathing fish, Misgurnus anguilliacaudatus

“…As a corollary, in a study on the euryhaline rainbow trout, salinity acclimation resulted in an increase in cytosolic and membrane-bound CA isoforms , which are involved in HCO 3 -secretion (Grosell et al, 2009a). Nevertheless, CA has been localized by enzyme histochemistry in the weatherloach digestive tract to both the 'stomach' (anterior intestine) and posterior intestine (Chang et al, 2006). Our results in the loach would indicate a role for transepithelial HCO 3 -secretion, making use of plasma HCO 3 -and a basolateral transporter such as NBC (Tokuda et al, 2007;Kurita et al, 2008), which is indirectly supported by the finding of ouabainsensitive (Na + /K + -ATPase inhibited) net base flux in the anterior intestine.…”