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The aim of the present study is to determine if Ahr ligands as PCB-126, a dioxin-like, might contribute to inhibition of the tumor suppressor p53 by promoting its degradation through proteasome-ubiquitin system (UPS). The findings show, in the presence of PCB-126, a significant increase of p53 immunoreactivity in fish compared to the control. Subsequently, there is a decrease of p53 immunoreactivity at 24h which is maintained even at 72h. At the same time there is a slight decrease of ubiquitin immunoreactivity to 12h compared to the control and a marked decrease to 24 and 72h. The induction of ubiquitin expression is resulted very marked in the control and preserved at 12h. It's very important to underline as in our study we demonstrate a marked decrease of ubiquitin and p53 immunoreactivity at 24h and 72h. AHR activation, by ligands as PCB-126, increases p53 ubiquitation inhibiting its expression, in addition it decreases the free ubiquitin promoting disruption of Ub homeostasis; this is the first report that establishes a relationship between AhR, increases p53 ubiquitation, and reduction of free ubiquitin. Our result emphasize the need to deeply the role of this receptor in UPS regulation as potential therapeutic target for cancer treatment., (Copyright © 2017. Published by Elsevier GmbH.)

The aryl hydrocarbon receptor (AHR) mediates a variety of biological responses to ubiquitous dioxin and PCB dioxin-like. AHR together with ARNT, AHRR, represent a novel basic helix-loop-helix/PAS family of transcriptional regulators. Their interplay may affect the xenobiotic response. The aim of this study was to investigate, by histological, immunohistochemical investigations and western-blot analysis, the expression of AHR, ARNT and AHRR in liver of seabrem (Spaurus aurata) after exposure at different time to dioxin-like PCB126 in order to deep the knowledge about their specific role. The findings showed a significant increase of AHR and ARNT expression in juvenile fishes after 12 h than control group. The induction of AHR and ARNT is also significant at 24 and 72 hours compared to the control group. Furthemore, induction of AHRR expression has proved to increase both 12 h but this induction does not seem significant to 24 and 72 hours. The most important data of this work is that the induction of AHRR, when the action of the toxic persistence substances, as dioxin and PCB-126, it is not enough to reduce AHR signaling and thus its hyperactivation leads to toxic effects in seabrem (Spaurus aurata). All this confirms the importance of AHR ligands as new class of drugs that can be directed against severe disease such as cancer.

Diabetic mice are characterized by a disrupted expression pattern of VEGF (vascular endothelial growth factor), and impaired vasculogenesis during healing. Experimental evidence suggests that RLX (relaxin) can improve several parameters associated with wound healing. Therefore we investigated the effects of porcine-derived RLX in diabetes-related wound-healing defects in genetically diabetic mice. An incisional wound model was produced on the back of female diabetic C57BL/KsJ-m+/+Lept(db) (db+/db+) mice and their normal littermates (db(+/+)m). Animals were treated daily with porcine RLX (25 μg/mouse per day, subcutaneously) or its vehicle. Mice were killed on 3, 6 and 12 days after skin injury for measurements of VEGF mRNA and protein synthesis, SDF-1α (stromal cell-derived factor-1α) mRNA and eNOS (endothelial NO synthase) expression. Furthermore, we evaluated wound-breaking strength, histological changes, angiogenesis and vasculogenesis at day 12. Diabetic animals showed a reduced expression of VEGF, eNOS and SDF-1α compared with non-diabetic animals. At day 6, RLX administration resulted in an increase in VEGF mRNA expression and protein wound content, in eNOS expression and in SDF-1α mRNA. Furthermore, the histological evaluation indicated that RLX improved the impaired wound healing, enhanced the staining of MMP-11 (matrix metalloproteinase-11) and increased wound-breaking strength at day 12 in diabetic mice. Immunohistochemistry showed that RLX in diabetic animals augmented new vessel formation by stimulating both angiogenesis and vasculogenesis. RLX significantly reduced the time to complete skin normalization and this effect was abrogated by a concomitant treatment with antibodies against VEGF and CXCR4 (CXC chemokine receptor 4), the SDF-1α receptor. These data strongly suggest that RLX may have a potential application in diabetes-related wound disorders.

The effects of polychlorinated biphenyl congeners 126 and 153 (PCB-126 and PCB-153) on vitellogenin (Vtg) and cytochrome (CYP1A1) expression were evaluated in 60 juvenile Sparus aurata. Fish were divided into four groups and the control group (Group A) was compared to fish exposed to PCB-126 (10-8M) (Group B), PCB-153 (10-6M) (Group C) singly and also in combination (Group D) for 12, 24 and 72 h. Hepatic expression of Vtg and CYP1A1 were analyzed using histological examinations and by immunochemical (Western blotting and immunohistochemistry) methods. Vtg increased in juvenile fishes of Groups B, C and D after 12h respect to Group A and decreased after 24 and 72 h respect to 12h in each group. CYP1A1 increased after 12 and 24h in all groups vs control group and increased in Group B only at 72 h vs in control group. The results showed that chemical interaction and endocrine disruption in fish might produce deleterious consequences not only for fish but also for human., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The presence of mast cells has been reported in all classes of vertebrates, including many teleost fish families. The mast cells of teleosts, both morphologically and functionally, show a close similarity to the mast cells of mammals. Mast cells of teleosts, localized in the vicinity of blood vessels of the intestine, gills and skin, may play an important role in the mechanisms of inflammatory response, because they express a number of functional proteins, including piscidins, which are antimicrobical peptides that act against a broad-spectrum of pathogens. An increase in the number of mast cells in various tissues and organs of teleosts seems to be linked to a wide range of stressful conditions, such as exposure to heavy metals (cadmium, copper, lead and mercury), exposure to herbicides and parasitic infections. This study analyzed the morphological localization and abundance of mast cells in the intestine and gills of sea bream, Sparus aurata, after a 12, 24 or 72 h exposure to PCB 126, a polychlorinated biphenyl, which is a potent immunotoxic agent. In the organs of fish exposed to PCB 126, it was observed that in addition to congestion of blood vessels, there was extravasation of red blood cells, infiltration of lymphocytes, and a progressive increase in numbers of mast cells. These data confirm the immunotoxic action of PCB, and the involvement of mast cells in the inflammatory response., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Immunohistochemical studies using antisera against various neuropeptides (Substance P, vasoactive intestinal polypeptide, and cholecystokinin octapeptide) and tyrosine hydroxylase revealed both olfactory sensory neuron (OSN) polymorphisms and transepithelial-subepithelial nerves in the olfactory epithelium of the cartilaginous fish, Scyliorhinus canicula. This study provides the first evidence of three morphological types of OSNs within the olfactory epithelium of cartilaginous fish that are similar to those found in the teleosts. In fishes there is evidence that OSNs differ functionally, including their differential olfactory bulb projections and molecular properties. The Substance P positive olfactory neurons in S. canicula may have a separate bulbar projection site that is not known, but may indicate a characteristic found in olfactory neuron subtypes in both lampreys and teleost fish. Numerous Substance P immunopositive nerves are found at the base of and in the olfactory epithelium. Some of them were observed to extend outwards almost reaching the epithelial surface. Their presumptive origin from the trigeminal nerve and their interrelationship with chemosensory cells in the nasal passages of vertebrates are discussed., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

Hyaluronic acid (HA), an essential component of the extracellular matrix, is an efficient space filler that maintains hydration, serves as a substrate for assembly of proteoglycans and is involved in wound healing. Although numerous pieces of evidence demonstrate beneficial effects in promoting wound healing in diabetes, a systemic approach has never been tested. We used an incisional wound healing model in genetically diabetic mice to test the effects of systemic injection of HA. Diabetic (n=56) and normoglycemic (n=56) mice were subjected to incision and randomized (8 groups of 7 animals each) to receive HA at different doses, 7.5, 15 and 30mg/kg/i.p., or vehicle (0.9% NaCl solution) for 12days. At the end of the experiment animals were sacrificed and skin wounds were excised for histological, biochemical and molecular analysis. Histology revealed that the most effective dose to improve wound repair and angiogenesis in diabetic mice was 30mg/kg. Furthermore HA injection (30mg/kg) improved the altered healing pattern in diabetic animals, increased skin remodeling proteins TGF-β and transglutaminase-II and restored the altered expression of cyclin B1/Cdc2 complex. Evaluation of skin from diabetic animals injected with HA revealed also an increase in HA content, suggesting that systemic injection may be able to restore the reduced intracellular HA pool of diabetic mice. Finally HA markedly improved skin mechanical properties. These promising results, if confirmed in a clinical setting, may improve the care and management of diabetic patients., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Cyclins drive cell-cycle progression by associating with their kinase partners, cyclin-dependent kinases (CDK). We investigated cyclin D1/CDK6, cyclin E/CDK2 complexes, and the cell-cycle negative regulators p15 and p27 in an incisional skin wound model., Methods: Wounds were produced on the back of female diabetic mice and their normoglycemic littermates. Animals were treated with polydeoxyribonucleotide (PDRN, 8 mg/kg/i.p.), an agonist of adenosine A2(A) receptors, or its vehicle daily. Granulation tissue proliferation by Ki67 immunostaining, cyclin D/CDK6 and cyclin E/CDK2 complexes, and p21 and p16 proteins (Western blot analysis), and the histologic changes were assessed at different days (3, 6, and 12 days after injury)., Results: Numerous Ki67 positive cells were observed at day 3 and day 6 in the granulation tissue of normoglycemic mice. Ki67 positive cells were fewer in diabetic than in normoglycemic mice. PDRN increased Ki67 positive cells in diabetic mice. Normoglycemic mice showed the greatest upregulation of cyclin D1, CDK6, cyclin E, and CDK2 at day 6. Diabetic mice had a markedly lower expression of cyclin D1, CDK6, cyclin E, and CDK2 at day 6. They also showed a greater expression of p15 and p27 at day 6. PDRN administration in diabetic mice increased cyclin D1/CDK6 and cyclin E/CDK2 expression and reduced p15 and p27 inhibitors at day 6 after injury; moreover, it improved the impaired wound healing at day 12., Conclusion: Our results suggest that adenosine A2(A) receptor activation by PDRN might represent a therapeutic strategy to overcome the diabetes-impaired cell-cycle machinery., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Ang-1 (angiopoietin-1) improves the ineffective angiogenesis and impaired wound healing in diabetes; however, the mechanism underlying this positive effect is still far from being completely understood. In the present study, we investigated whether rAAV (recombinant adeno-associated virus)-Ang-1 gene transfer could improve wound repair in genetically diabetic mice (db+/db+) and the mechanism(s) by which it causes new vessel formation. An incisional skin-wound model in diabetic and normoglycaemic mice was used. After the incision, animals received rAAV-LacZ or rAAV-Ang-1 in the wound edge. After 7 and 14 days, wounds were used to (i) confirm Ang-1 gene transfer, (ii) assess histologically the healing process, (iii) evaluate wound-breaking strength, and (iv) study new vessel formation by PECAM-1 (platelet/endothelial cell adhesion molecule-1) immunostaining. Finally, we investigated VEGF (vascular endothelial growth factor) mRNA and protein levels, eNOS (endothelial NO synthase) expression and VEGFR-1 and VEGFR-2 (VEGF receptor-1 and -2 respectively) immunostaining. The efficiency of Ang-1 gene transfer was confirmed by increased mRNA and protein expression of the protein. rAAV-Ang-1 significantly improved the healing process, stimulating re-epithelization and collagen maturation, increasing breaking strength and significantly augmenting the number of new vessels, as indicated by PECAM-1 immunostaining. However, Ang-1 gene transfer did not modify the decrease in VEGF mRNA and protein expression in diabetic mice; in contrast, Ang-1 increased eNOS expression and augmented nitrate wound content and VEGFR-2 immunostaining and protein expression. Ang-1 gene transfer did not change vascular permeability. Similar results were obtained in normoglycaemic animals. In conclusion, our results provide strong evidence that Ang-1 gene transfer improves the delayed wound repair in diabetes by inducing angiogenesis in a VEGF-independent manner.

Statins have different effects beyond cholesterol reduction and stimulate angiogenesis. We investigated the effect of simvastatin in diabetes-related healing defects. An incisional skin wound model produced on the back of female diabetic mice (db(+)/db(+)) and their normoglycemic littermates (db(+)/(+)m) was used. Animals were treated daily either with simvastatin (5 mg/(kgi.p.)) or vehicle. Mice were killed on different days (3, 6 and 12 after skin injury) for measurement of vascular endothelial growth factor (VEGF) mRNA and protein expression, to assess histologically the healing process and to evaluate wound breaking strength and angiogenesis by CD31 immunostaining. Simvastatin administration in diabetic mice increased VEGF mRNA (simvastatin=4.8+/-0.6n-fold/beta-actin; vehicle=2.3+/-0.4n-fold/beta-actin) and protein expression (simvastatin=5+/-0.7 integrated intensity; vehicle=2.2+/-0.3 integrated intensity) and enhanced nitric oxide wound content at day 6. Additionally, the statin augmented breaking strength and PECAM-1 immunostaining at day 12. Finally, simvastatin administration restored the impaired wound healing process in diabetic mice. Similar results were obtained in normoglycaemic mice. Passive immunization with anti-VEGF antibody (10 microg/mouse) completely abrogated the beneficial effects of simvastatin on healing in diabetic mice. Simvastatin has potential application in diabetes-related wound healing disorders.

We investigated the effects of raxofelast, a lipid peroxidation inhibitor, in an experimental model of burn wounds. C57BL/6 male mice of 25-30 g were immersed in 80 degrees C water for 10 seconds to achieve a partial-thickness scald burn. Animals received intraperitoneally either raxofelast (20 mg/kg/day for 14 days in 100 microL) or its vehicle alone (100 microL/day for 14 days). On day 14, burn areas were used for measuring conjugated dienes, reduced glutathione levels, histological damage, neoangiogenesis by immunohistochemistry and expression (Western blot) of the specific endothelial marker CD31 as well as quantification of microvessel density, VEGF wound content, endothelial and inducible nitric oxide synthase (eNOS and iNOS) expression and wound nitrite content. Raxofelast decreased tissue conjugated dienes (vehicle 6.1 +/- 1.4 DeltaABS/mg protein; raxofelast 3.7 +/- 0.8 DeltaABS/mg protein), prevented tissue glutathione consumption (vehicle 3.2 +/- 0.9 micromol/g protein; raxofelast 6.7 +/- 1.8 mumol/g protein), increased epithelial proliferation, extracellular matrix maturation, and augmented neoangiogenesis as suggested by the marked increase in microvessel density and by the robust expression of the specific endothelial marker CD31 (vehicle 9.4 +/- 1.1 integrated intensity; raxofelast 14.8 +/- 1.8 integrated intensity). Furthermore, raxofelast enhanced VEGF wound content (vehicle 1.4 +/- 0.4 pg/mg protein; raxofelast 2.4 +/- 0.6 pg/mg protein), caused a marked expression of eNOS (vehicle 16.1 +/- 3 integrated intensity; raxofelast 26.2 +/- 4 integrated intensity) and iNOS (vehicle 9.1 +/- 1.8 integrated intensity; raxofelast 16.2 +/- 3.5 integrated intensity) and increased wound nitrite content. Lipid peroxidation inhibition by raxofelast may be an effective therapeutic approach to improve clinical outcomes after thermal injury.

The innervation of the respiratory tract of amphibians is still poorly understood. Therefore, the respiratory tracts of the frogs Rana esculenta and Discoglossus pictus have been investigated in order to describe non-adrenergic non-cholinergic (NANC) and adrenergic innervation, and the localization of neuromediators that are possibly involved. Immunohistochemical staining of many bioactive substances was found in neuroepithelial cells of the buccopharynx, larynx, lung septa, nerves and neurons throughout the airway system. The findings indicate the occurrence of vasoactive intestinal peptide (VIP)-immunopositive nerve fibers in fibromuscular septa and the vasculature, nitrergic innervation of the large pulmonary veins showing a plexus of nNOS-immunopositive nerve fibers that also innervate the lung wall and the localization of neuronal nitric oxide synthase (nNOS) in neurons in the lung wall. In addition, laryngeal blood vessels and small arteries in the wall of septa that form capillary networks are supplied by enkephalin-immunopositive nerve terminals. We conclude that the airway system of the two frog species studied is innervated by a parasympathetic NANC system. Adrenergic innervation was also found that was immunostained for tyrosine hydroxylase. Adrenergic fibers were mainly present in muscles in septal edges, arteries present in septa and the wall of the lung. It is suggested that nNOS-positive and leu-enkephalin-positive neurons mediate vasodilation via the release of NO, but the nature of the NANC innervation remains obscure. Despite the many pharmacological studies of the lungs of amphibians, the physiological role of pulmonary autonomic innervation remains poorly understood.

Objective: The purpose of this study was to investigate the effect of recombinant adeno-associated viral (rAAV) vector-mediated human vascular endothelial growth factor (VEGF165) transfer on experimental burn wounds., Design: Randomized experiment., Setting: Research laboratory., Subjects: C57BL/6 male mice weighing 25-30 g., Interventions: Mice were immersed in 80 degrees C water for 10 secs to achieve a partial-thickness scald burn. Animals were randomized to receive at two injection sites on the edge of the burn either 1011 copies of the rAAV-VEGF165 or the vector carrying the control and inert gene beta-galactosidase (rAAV-LacZ). On day 14 the animals were killed. Burn areas were used for histologic examination, evaluation of VEGF expression (immunohistochemistry) and VEGF wound content (enzyme-linked immunosorbent assay), determination of wound nitrite, and measurement of messenger RNA (mRNA) for endothelial and inducible nitric oxide synthase (eNOS and iNOS)., Measurements and Main Results: rAAV-VEGF165 increased epithelial proliferation, angiogenesis, and maturation of the extracellular matrix. Furthermore, gene transfer enhanced VEGF expression, studied by immunohistochemistry, and the wound content of the mature protein (rAAV-LacZ, 11 +/- 5 pg/wound; rAAV-VEGF165, 104 +/- 7 pg/wound). Moreover, VEGF165 gene transfer increased wound content of nitrate. Finally, rAAV-VEGF165 administration enhanced the messenger RNA for eNOS (rAAV-VEGF165, 1.1 +/- 0.2 relative amount of eNOS mRNA; rAAV-LacZ, 0.66 +/- 0.3 relative amount of eNOS mRNA) and iNOS (rAAV-VEGF165, 0.8 +/- 0.09 relative amount of iNOS mRNA; rAAV-LacZ, 0.45 +/- 0.05 relative amount of iNOS mRNA)., Conclusion: Our study suggests that rAAV-VEGF gene transfer may be an effective therapeutic approach to improve clinical outcomes after thermal injury.

Gill and air sac of the Indian catfish Heteropneustes fossilis harbour a nerve network comprising an innervated system of neuroepithelial endocrine cells; the latter cells are found especially in the gill. A series of antibodies was used for the immunohistochemical detection of neurotransmitters of the neural non-adrenergic, non-cholinergic (NANC) systems such as the sensory neuropeptides (enkephalins), the inhibitory neuropeptide VIP and neuronal nitric oxide synthase (nNOS) responsible for nitric oxide (NO) production which is an inhibitory NANC neurotransmitter. NADPH-diaphorase (NADPH-d) histochemistry was used as marker of nNOS although it is not a specific indicator of constitutively-expressed NOS in gill and air sac tissues. A tyrosine hydroxylase antibody was used to investigate adrenergic innervation. Nitrergic and VIP-positive sensory innervation was found to be shared by gill and air sac. Immunohistochemistry revealed the presence of enkephalins, VIP, NOS and NADPH-d in nerves associated with branchial and air sac vasculature, and in the neuroendocrine cell systems of the gill. Adrenergic nerve fibers were found in some parts of the air sac vasculature. The origin of the nerve fibers remains unclear despite previous findings showing the presence of both NADPH-d and nNOS in the sensory system of the glossopharyngeal and vagus nerves including the branchial structure. Scarce faintly stained nNOS-positive neurons were located in the gill but were never detected in the air sac. These findings lead to the conclusion that a postganglionic innervation of the airways is absent. Mucous goblet cells in the gill were found to express nNOS and those located in the non-respiratory interlamellar areas of the air sac were densely innervated by nNOS-positive and VIP-positive nerve fibers. Our immunohistochemical studies demonstrate that most arteries of the gill and air sac share a NANC (basically nitrergic) innervation which strongly suggests that they are homologous structures.

Chicks were treated at 2 weeks of age with 4,15, 40, 100 and 150 mg/kg of monensin, an ionophore used for its anticoccidial and growth-promoting properties. In the present immunohistochemical study, the expressions and distribution of Na+/K(+)-ATPase and Ca(++)-ATPase were studied in myocardium and skeletal muscles (pectoral and quadriceps femoris). We detected an increase of Na+/K(+)-ATPase immunostaining with prominent staining of the sarcolemma and a slight increase of Ca(+)-ATPase with prominent staining of the sarcoplasma.

An immunohistochemical characterization of cytokeratins in the skin tissues of the sea lamprey, Petromyzon Marinus was performed using a panel of monoclonal antibodies. Cytokeratins typical for simple epithelia have been detected in the epithelial cells, with a 8/18 pair expression. Granular cells and skein cells showed a labelling of cytokeratins 7, 8, 18 and 19, that is observed also in the non-keratinized layers of the horny teeth. Similar cytokeratins occur in the outermost cell layers of the epidermis; cytokeratin 19 shows a comparatively weaker reaction. These results suggest that the cytokeratin patterns in the above types of cells of adult epidermis are quite different from those in ammocoetes where the expression of cell specific cytokeratins may be correlated with specific programs of epidermal differentiation.

The presence of calbindin D28K in fish (Heteropneustes fossilis) gill was studied by use of specific antibodies raised against chick duodenal 28 kDa calbindin in immunoperoxidase and electron-microscopic labelling experiments. Immunoreactivity for calbindin D28K, which has been observed in the intestine of a number of avian and mammalian species, is reported for the first time in the gill. It was primarily located in neuroendocrine (NE) cells. Some immunoreactivity was also located in the glycocalyx of the non-endocrine cells, i.e., the pavement cells, which have ultrastructural characteristics quite different from those of endocrine cells. The calbindin-immunopositive NE cells were ascertained in both gill filamental and lamellar epithelium. All the NE cells contained secretory granules as the most distinctive feature of these cells. Ultrastructurally, two types of NE cells were distinguished according to the morphology of their secretory granules. The calbindin immunoreactivity in the NE cells was stimulated when the calcium concentration of the ambient water was reduced. The present findings suggest that NE cells exert some as yet unidentified function related to calcium-mediated processes involving the expression of calbindin.

The surface epidermis of Ambystoma tigrinum larvae was examined at the light- and electron-microscope levels using five different lectin conjugates as probes for the detection of sugar residues on the cell membranes. Concanavalin A (Con-A), wheat-germ agglutinin (WGA), Ricinus communis agglutinin I (RCA-I), Dolichos biflorus agglutinin and soybean agglutinin (SBA) conjugates clearly labelled the surface cells, especially their apical surfaces. At electron microscopy, the labelling on plasma membranes was found to exhibit regional differences. Among the lectins tested WGA displayed a particularly characteristic binding pattern. WGA also bound to basolateral cell surfaces, including the tight-junction zone which was also stained by the RCA-I conjugate. The different labelling intensity and staining patterns obtained with the conjugates indicated the polarity of the cell surfaces. It is also assumed that the WGA staining of the basolateral membranes and intercellular spaces reflected transcellular transport, which is facilitated by acidic glycoconjugates. Other functional aspects of the polarized distribution of the lectin conjugates were also correlated with the receptor sites of certain sugar residues.

From examination of the structural data obtained for the tongue of rodent Jaculus jaculus, it has been possible to deduce that it is lined with filiform papillae in the dorsal epithelium and that it has a rich glandular apparatus consisting of anterior serous glands which are located immediately after the apex and composed of epithelial cells arranged in a single synctitial layer, and both nucous and seromucous acini (Weber's glands) in the posterior portion of the tongue on the lateral sides and ventromedian region respectively. In the tip glands there is an elaboration of protein material; both neutral and acid glycoproteins are absent. In the posterior Weber's glands acidic moieties in the mucosubstances are due mainly to sialomucins and hyaluronidase resistant sulfomucins; in the seromucous acini on the other hand, mucopolysaccharides with vicinal hydroxyl groups and proteins are present. The histoenzymological tests employed to detect the succinic dehydrogenase and carbonic anhydrase also revealed the two reactions in the seromucous acini. Their presence is discussed on the basis of their having a probable role in the salivary production mechanisms in the same way as those cells which have a very strong secretory activity, or those involved in ionic reabsorption processes. The role of granular catalase activity in the duct cells is assumed to be able of protecting the glandular parenchyma from bacterial attacks. The presence also of acid glycoproteins within the lingual glands is correlated with taste sensation in view of the current revaluation of the role played by the proteoglycans in neuronal functions.

The histochemistry of various oxidative enzymes and complex carbohydrates in the epidermis of the catfish Heteropneustes fossils was investigated after exposure to sublethal concentrations of the detergent sodium alkylbenzenesulphonate. It was found that the detergent treatment was accompanied by a marked increase in the number of mucous cells which produce histochemically detectable amounts of acidic glycoproteins with a shift towards the production of O-acetylated sialic acids. The activities of mitochondrial enzymes were lost in the superficial cell layers. In contrast the activities of glucose-6-phosphate and lactate dehydrogenase increased considerably. The rise in glucose-6-phosphate dehydrogenase was correlated with the metabolic requirements for the enhanced production of mucus under stress. The changes in both enzyme activities and in the chemical composition of mucus may provide a suitable experimental model for histochemical investigations of the effects of stress induced by pollutants on aquatic organisms.

Concanavalin A (Con A) lectin from jack bean Canavalia ensiformis DC binds to alpha-D-glucopyranosyl and alpha-D-mannopyranosyl residues of the cuticular secretions (glycocalyx) attached to apical plasma membrane in the skin surface cells of Blennius sanguinolentus. The presence of Con A positive carbohydrate components is also observed in some secretory vesicles close under the apical cell membrane and in the goblet cell secretion spread over the surface of the skin. Other lectin labeling methods might offer a new tool for the cytochemical demonstration of glycoconjugates containing sugar residues on plasmic membranes of the epithelial cells. This can provide an insight into the functional significance of the carbohydrate moieties, attributable to the specialization of the cell membranes.

The structure and the histochemical characteristics of the epidermis of the marine catfish Plotosus lineatus were determined with a series of recent techniques employed either alone or in combination with other procedures to detect selectively sialic acid containing glycoproteins or other acidic carbohydrates. The epidermis consists of a multilayered epithelium where are recognizable various cell types namely, the epithelial cells, the club cells and the mucous or goblet cells the latter concentrated mainly in the outermost layer. The goblet cells and the epithelial cells in the outer epidermis produced both neutral and acidic glycoproteins. The epithelial cells store also acidic glycoproteins containing high amounts of sulphate esters (sulphomucins). The absence of the sialic acid is also discussed.