Separation by velocity sedimentation of the gill epithelial cells and their ATPases activities in the seawater adapted eel Anguilla anguilla L

New Aspects of the Extraction of Chitin from Squid Pens

In this work, we studied the extraction of beta chitin from squid pens. The characterization by ICP of the raw material confirmed the significant absence of calcium carbonate and then the possibility to definitely avoid a step of demineralization responsible for chain degradation. The kinetics studies associated with the extraction of lipid parts showed the important role played by the latter structures on the limitation of the protein extraction by a simple treatment in an aqueous solution of 1 M NaOH. The role of various parameters such as the size of the particles, time and number of steps, and the concentration in sodium hydroxide was studied. The determination of the molecular characteristics (molecular weight and degree of acetylation) allowed us to define the optimal conditions of deproteinization in relation with the best preservation of these characteristics.

Histological changes and copper accumulation in liver and gills of the Senegales sole, Solea senegalensis

Senegales sole, Solea senegalensis, adult specimens were subjected to sublethal copper exposure (100 microg SO(4)Cu/L) for 7 days (contamination period) and afterward kept for 4 days without copper exposure (depuration period). In contaminated and detoxified specimens, the hepatocytes indicated a great number of lipid droplets compared to the control specimens. Some ultrastructural alterations such as partial disruption of the microvilli and endothelial lining of the sinusoids were observed in the hepatocytes. Lifting and swelling of the lamellar epithelium were common lesions in S. senegalensis gills due to the copper exposure. On the other hand, in contaminated and detoxified specimens, gills demonstrated separation of respiratory epithelium; chloride and pavement cells were also altered. Copper levels in gills, and especially in liver, increased during sublethal copper exposure (up to 7 days). During the detoxification period, Cu concentrations in gills and liver experienced variable changes. The results of the study indicate that histology is a successful tool capable of revealing sensitively and selectively even the sublethal effects of heavy metals on the environment and aquatic biota.

The eicosanoid generating capacity of isolated cell populations from the gills of the rainbow trout, Oncorhynchus mykiss

Rainbow trout gill filaments generated a wide range of eicosanoid products following calcium ionophore challenge. The putative lipoxygenase products were separated by reverse phase high performance liquid chromatography (RP-HPLC), while prostanoids were quantified by enzyme immunoassay. Three main monohydroxy compounds containing conjugated dienes were observed after RP-HPLC namely 12-(S) hydroxyeicosatetraenoic acid (12-HETE), 12-(S) hydroxyeicosapentaenoic acid (12-HEPE) and 14-(S) hydroxydocosahexaenoic acid (14-HDHE), derived from endogenous arachidonic, eicosapentaenoic and docosahexaenoic acids, respectively. Their identification was confirmed by mass spectrometry. A further five compounds containing conjugated trienes were also observed but in lesser amounts. One of these products was identified as 8,15-dihydroxyeicosatetraenoic acid (8,15-DiHETE) based on its UV spectrum, co-elution with authentic standard on RP-HPLC and mass spectrometry. Overall, the generation of these products suggests the presence of 12- and possibly 15-lipoxygenase activities in trout gill acting on endogenous sources of fatty acid. To determine if the various cell types in trout gill had differing eicosanoid generating potential, gills were disrupted and the resultant cell suspensions separated by density gradient centrifugation. Following this three bands were formed on the gradients and the cell populations from these were characterised using periodic acid Schiff's (PAS) reactivity for mucosubstances, haematoxylin and eosin staining, and immunoreactivity with both monoclonal and polyclonal antibodies. The first band consisted of polygonal cells and other more minor cell types, the second cell band contained mainly polygonal and PAS-positive goblet epithelial cells, while the third band consisted of mainly erythrocytes. There were significant differences in the eicosanoid generating potential of the isolated cells, with cells from the second band generating significantly more 12-HETE and 8,15-DiHETE than those from both the first band and unfractionated populations. The eicosanoid generating activity of the trout gill epithelial cell line, RTG-W1, was also elucidated. It proved to be a modest generator of eicosanoids in that only low levels of thromboxane B2 and prostaglandin E2 were detected while no lipoxygenase products were observed.

Isolation of viable cell types from the gill epithelium of Japanese eel Anguilla japonica

High-purity viable cells with low mitochondria (pavement cells) and mitochondria-rich content (chloride cells) were successfully isolated from the gill epithelium of Japanese eels, using three-step Percoll gradient low-speed centrifugation. Cytochemistry (silver staining for chloride, rhodamine-123, and Mitotracker for mitochondria and actin/spectrin immunofluorescence) and scanning electron microscope images were used to identify the cell types in the gill epithelium of the eel. Pavement cells were isolated at 97 and 98% purity for freshwater- and seawater-adapted eels, respectively, and chloride cells were obtained at 89 and 92% purity. The enzymatic activities of the isolated cells were determined. Na+-K+-ATPase, Mg2+-ATPase, and succinate dehydrogenase were found mainly in the chloride cell. Alkaline Ca2+-ATPase and low- and high-affinity Ca2+-ATPase were about twice as high in the chloride cell compared with the pavement cell. Transfer of eels to seawater resulted in enlargement of chloride cell sizes and significant increases in Na+-K+-ATPase, Mg2+-ATPase, and succinate dehydrogenase activities, while all Ca2+-ATPases declined by approximately 60-80%. This is the first report demonstrating the successful isolation of freshwater chloride cells and also an exclusive method of getting high-purity seawater chloride cells. The isolated cells are viable and suitable for further cytological and molecular studies to elucidate the mechanisms of ionic transport.

Simultaneous recognition of ionocytes and mucous cells in the gill epithelium of turbot and in the rat stomach

A simple and rapid method is described which allows the recognition of different types of epithelial cells in one paraffin section. In the fish gill, the "chloride cells" (also called ionocytes or mitochondria-rich cells) appeared black and well contrasted after the zinc iodideosmium (ZIO) fixation, a contrast which is preserved after staining with alcian blue. All mucous cells appeared pale beige and can be clearly distinguished from the other cells but the known specificity of alcian blue for acid and sulfate mucins was lost. A complex tissue like the gill showed an interesting metachromasia. The combined ZIO fixation and alcian blue staining has also been applied on another epithelium, the rat stomach.