Sialic acids in epithelial tissues of Carassius auratus gibelio (bloch) (prussian carp), Cottus gobio L. (bullhead) and Myoxocephalus scorpius (L.) (bull rout)

Effects of two water disinfectants (chloramine T and peracetic acid) on the epidermis and gills of Garra rufa used in human ichthyotherapy

Doctor fish (Garra rufa) have recently been used for aesthetic purposes and as a medical treatment in patients with psoriasis (ichthyotherapy). For this particular kind of human therapy it is essential to guarantee adequate hygienic conditions for both people and fish. The aim of this study was to test two concentrations of water disinfectants, chloramine T and peracetic acid, on Garra rufa to ascertain possible exposure damage to the epidermis and gills. Fish were exposed to 2 mg/l and 10 mg/l of chloramine T and to 15 μl/l and 45 μl/l of peracetic acid in a 40-minute static bath up to six times a day for one week. The epidermis and gills were checked for histological changes and the number of epidermal mucous cells, club cells and taste buds were quantified; mucous cells were also characterized histochemically to detect alterations in mucin production. No mortality or severe histological changes were found in treated or control fish. Cell count showed a significant increase (p<0.05) in mucous cells (mean 49.1 ± 6.7 vs 37.0 ± 13.1 of controls) in animals treated with peracetic acid independently of the dose. Club cell number showed a significant (p<0.05) decrease in fish treated with 2 mg/l of chloramine T (mean 74.3 ± 15.6) and with 45 μl/l of peracetic acid (mean 78.17 ± 10.5) compared to controls (mean 107.0 ± 19.2). Histochemical evaluation of mucous cells did not reveal changes in mucin type in fish exposed to the two disinfectants. The results suggest a good tolerability of Garra rufa to the two disinfectants at the concentrations tested.

Comparative ionic flux and gill mucous cell histochemistry: effects of salinity and disease status in Atlantic salmon (Salmo salar L.)

Two experiments were conducted to assess the physiological effects of freshwater exposure and amoebic gill disease (AGD) in marine Atlantic salmon (Salmo salar L.). The first experiment monitored marine salmon during a 3 h freshwater exposure, the standard treatment for AGD in Tasmania. The second experiment described the gill mucous cell histochemistry for freshwater adapted and seawater acclimated fish (AGD affected and unaffected) for possible correlations to ionoregulation. When exposed to freshwater, marine Atlantic salmon experienced a minor ionoregulatory dysfunction represented by a net efflux of Cl(-) ions at 3 h. AGD affected fish experienced the net efflux of Cl(-) ions 1 h sooner, and had a significantly greater net efflux of total ammonia. Changes to gill mucous cell populations corresponded to differing salinity and the presence of AGD. In AGD affected fish, these populations significantly differed between lesion and non-lesion associated areas of the gill filament. Our results have shown changes in the ionoregulatory capacity of Atlantic salmon due to freshwater exposure and AGD. Gill mucous cell histochemistry indicates the potential importance of the mucous layer in ionoregulation and disease. In comparison to previous studies on rainbow trout, these results suggest that Atlantic salmon have a greater short-term ionoregulatory capacity.

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

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.