Mucosubstance histochemistry in control and acid‐stressed epidermis of brown bullhead catfish, lctalurus nebulosus (LeSueur)

Abstract

Glycoprotein components of epidermal mucous cells in control (pH 6.8) and acid-stressed (pH 5.8, 4.8, 4.0) brown bullhead catfish were studied by histochemical and autoradiographic methods. Following exposure to acid, increased numbers of epidermal mucous cells were noted in all tissue sites studied, particularly dorsal and ventral skin. Mucous cells of control fish and acid-stressed (pH 5.8) fish contained a mixture of neutral and acidic mucosubstances, the latter including both sialomucins and sulfomucins, with sialomucins predominating. An apparent shift toward increased sulfomucin production was observed in skin from fish exposed to pH 4.8 and 4.0. In addition, autoradiographic studies using 35S showed increased labeling of mucous cells in acid-exposed (pH 4.0) epidermis, offering further support for a shift toward sulfomucin production in acid-stressed fish. Absence of appreciable sulfomucin production in younger fish (less than 1 year old) suggested that this shift may be partly age-dependent. The functional significance of increased sulfomucin production in acid-stressed epidermal mucous cells is uncertain but may be related to maintenance of ionic equilibrium.

Histopathological changes induced by ambient ammonia (ammonium sulphate) on the opercular linings of the catfish Heteropneustes fossilis

“…This might delay the damage due to the deleterious effects of the toxicants. Zuchelkowski et al (1985) also observed a n apparent shift towards increased sulfomucin production in the epidermal MCs of acid-stressed lctalurus nebulosus (Lesueur) and suggested that the functional significance of increased sulfomucin production may be related to maintenance of ionic equilibrium. Due to the active flow of water across the gills, which is necessary for respiration, the risk that slimy secretions of the opercular epidermis will be continuously washed away is also much greater than in the case of general body skin.…”

Physiology and immunology of mucosal barriers in catfish (Ictalurus spp.)

“…Mucus cell numbers have been shown to be sensitive to dietary changes, stress and handling in other Ictalurus species and to water temperature in channel catfish. 23,24 Work by our group has identified expression patterns of MUC2, MUC5AC, MUC19 and related isoforms in catfish gill. Examination of fish susceptible to the common freshwater pathogen, Flavobacterium columnare, revealed basally higher levels of goblet cells ( Fig.…”

Histochemical Analysis of Glycoproteins in the Epidermal Mucous Cells and Sacciform Cells of an Indian Swamp Eel Monopterus Cuchia (Hamilton) (Synbranchiformes, Pisces).

“…Nevertheless, Whitear and Mittal (53) conceived that such a shift could be related to a greater likelihood of infection in fresh water. In the skin of acid stressed catfish Ictalurus nebulosus, Zuchelkowski et al (61) found a shift towards increased production of sulphomucins and correlated this with the maintenance of ionic equilibrium.…”

“…Previous studies have shown that principal constituents of mucus secreted by fish epidermis consists, in general, of macromolecules of complex and diversified natures including glycoproteins (GPs) (3,21,33,52,59,60,61). Different classes of GPs have been postulated to serve a variety of physiological activities in mammalian tissues (5,11,31,32,34,38,46,47,50).…”