Immunoreactivity to calcium‐binding proteins (CaBPs) in the epithelia of skin and gill of the catfish,Heteropneustes fossilis

Abstract

The skin and gill epithelia of Heteropneustes fossilis have been shown to possess specific patterns of immunoreactivity for the antisera against a set of calcium-binding proteins such as calmodulin, parvalbumin, S-100 protein, and calbindin D28K. In the epidermis, both the more superficial cells and the club cells reacted positively for all the calcium-binding proteins tested, except for calbindin D28K in the former and for parvalbumin in the latter. As in the club cells of the epidermis, also in the gill all the calciumbinding protein antisera, except anti-parvalbumin, appear to stain neuroendocrine cells scattered throughout these epithelia. The colocalization of a serotonin reactivity in the S-100 protein positive cells confirms the qualification of these branchial cells as being of the neuroendocrine type.

Effect of natural confinement on the gill cell types and bony elements ofLebias fasciata(Teleostei, Cyprinodontidae): A morphological and immunohistochemical analysis

“…They represent two rather distinct types of neuroepithelial cells that presumably have different anatomical distribution patterns (Burleson & Smatresk, 1990a, b;Burleson et al, 1992;Sundin et al, 1998). This also seems to be consistent with the data for the calcium-binding proteins, S-100 and Cb D28K (Fasulo et al, 1998), and the cytokeratin CK18 , which are considered markers of neuroendocrine cells. With regard to the calcium-binding proteins, a different distribution was found in the two environments between the cells immunopositive to calbindin, prevalent at Ganzirri, and those immunopositive to protein S-100.…”

“…/ Another important effect, demonstrated experimentally in an acid environment (Malley & Chang, 1985;Verbost et al, 1989Verbost et al, , 1992Flik, 1989), is the interference of Al 3+ with the absorption of Ca ++ by chloride cells. The interaction of calmodulin, basic cytokeratin (AE3) and high molecular weight cytokeratin (KLl) suggests an apoptotic effect mediated by calmodulin in correlation with the disruptive activity of Ca ++ on the cytoskeleton (Dowd et al, 1992;Dowd, 1995;Fasulo et al, 1998).…”

“…Therefore, the neuroendocrine cells (paraneurons) distributed in the epithelium play a fundamental role, with a strongly homeostatic nature, in the regulation and modulation of gill functions. The identification and immunohistochemical characterization of these specialized cells in the branchial epithelium of the catfish Heteropneustes fossilis (Zaccone et al, 1992(Zaccone et al, , 1996Fasulo et al, 1998) and the study of the effects on them, under various conditions of environmentally induced stress, are an important reference for the comprehension of how the numerous functions of the gills are locally regulated and coordinated. For this purpose, the local vascular role exerted by the vasoactive substances endothelin and NO was recently investigated in the gills (Zaccone etal, 1996;Mauceri etal, 1999).…”

Paraneurons in the gills and airways of fishes

“…Calbindin immunoreactivity has been demonstrated in the granules of NE cells in fish maintained in normal and reduced calcium concentration of the ambient water. Light microscope immunohistochemistry identified calmodulin and S-100 protein in NE cells of the gill filament and lamellar epithelium of the catfish H. fossilis (Fasulo et al, 1997;Zaccone et al, 1994Zaccone et al, , 1995.…”

“…In most teleost fish species the NE cells were identified using antibodies against serotonin, met-5-enkephalin, leu-5-enkephalin (Zaccone et al, 1992a), calbindin DK28 (Zaccone et al, 1992b), NSE, calmodulin and S-100 protein (Fasulo et al, 1997;Zaccone et al, 1994Zaccone et al, , 1995 as well as endothelin (Zaccone et al, 1996) (Figs. 4-7).…”