The Effect of Prolactin on the Number of Membrane-Associated Particles in Kidney Cells of the Euryhaline Teleost Gasterosteus aculeatus during Transfer from Seawater to Freshwater:A Freeze-Etch Study

The membranes of kidney cells of 3-spined sticklebacks were examined in freeze-etch replicas. The numbers of particles adhering to surfaces and fracture faces of the outer cell membranes and the membranes of the basal labyrinth were determined. The latter membranes probably are the main location of ion-transporting enzyme complexes. The total number of particles per cell in freshwater fish exceeds that of seawater fish by about 50 % for the outer cell membrane, and by almost 200 % for the membranes of the basal labyrinth. After transfer of seawater fish to freshwater, particle numbers increase and their densities approximate freshwater values after 20 h. This rise in particle numbers coincides with the increase of ion-transporting activity of the cells known to take place after transfer to freshwater. The rate of increase of particle densities is enhanced after injection of ovine prolactin. This hormone is known to stimulate Na+/K+-ATPase activity of the basal labyrinth of teleost kidney cells. The results indicate that the particles represent enzyme complexes. The number of particles is probably under hormonal control. The increase in particle densities after transfer to freshwater is accompanied by a rise in the number of nuclear pores, which is noticeable by 10 h. No changes were observed in the density of the particles adhering to the fracture faces of gap junctions

The Effect of Prolactin on the Number of Membrane-Associated Particles in Kidney Cells of the Euryhaline Teleost Gasterosteus aculeatus during Transfer from Seawater to Freshwater:A Freeze-Etch Study

The membranes of kidney cells of 3-spined sticklebacks were examined in freeze-etch replicas. The numbers of particles adhering to surfaces and fracture faces of the outer cell membranes and the membranes of the basal labyrinth were determined. The latter membranes probably are the main location of ion-transporting enzyme complexes. The total number of particles per cell in freshwater fish exceeds that of seawater fish by about 50 % for the outer cell membrane, and by almost 200 % for the membranes of the basal labyrinth. After transfer of seawater fish to freshwater, particle numbers increase and their densities approximate freshwater values after 20 h. This rise in particle numbers coincides with the increase of ion-transporting activity of the cells known to take place after transfer to freshwater. The rate of increase of particle densities is enhanced after injection of ovine prolactin. This hormone is known to stimulate Na+/K+-ATPase activity of the basal labyrinth of teleost kidney cells. The results indicate that the particles represent enzyme complexes. The number of particles is probably under hormonal control. The increase in particle densities after transfer to freshwater is accompanied by a rise in the number of nuclear pores, which is noticeable by 10 h. No changes were observed in the density of the particles adhering to the fracture faces of gap junctions

In vivo bafilomycin-sensitive Na+ uptake in young freshwater fish

Contains fulltext : 14189.PDF (publisher's version ) (Open Access

Infection with low numbers of the sea louse Lepeophtheirus salmonis induces stress-related effects in postsmolt Atlantic salmon (Salmo salar)

Contains fulltext : 14155.PDF ( ) (Open Access

The Effect of Prolactin on the Number of Membrane-Associated Particles in Kidney Cells of the Euryhaline Teleost Gasterosteus aculeatus during Transfer from Seawater to Freshwater:A Freeze-Etch Study

The membranes of kidney cells of 3-spined sticklebacks were examined in freeze-etch replicas. The numbers of particles adhering to surfaces and fracture faces of the outer cell membranes and the membranes of the basal labyrinth were determined. The latter membranes probably are the main location of ion-transporting enzyme complexes. The total number of particles per cell in freshwater fish exceeds that of seawater fish by about 50 % for the outer cell membrane, and by almost 200 % for the membranes of the basal labyrinth. After transfer of seawater fish to freshwater, particle numbers increase and their densities approximate freshwater values after 20 h. This rise in particle numbers coincides with the increase of ion-transporting activity of the cells known to take place after transfer to freshwater. The rate of increase of particle densities is enhanced after injection of ovine prolactin. This hormone is known to stimulate Na+/K+-ATPase activity of the basal labyrinth of teleost kidney cells. The results indicate that the particles represent enzyme complexes. The number of particles is probably under hormonal control. The increase in particle densities after transfer to freshwater is accompanied by a rise in the number of nuclear pores, which is noticeable by 10 h. No changes were observed in the density of the particles adhering to the fracture faces of gap junctions

Fatty acids from the cyanobacterium Microcystis aeruginosa with potent inhibitory effects on fish gill Na+/K+-ATPase activity

Contains fulltext : 14258.pdf (publisher's version ) (Open Access

Na+/K+-ATpase immunoreactivity in branchial chloride cells of Oreochromis mossambicus exposed to copper

Contains fulltext : 14130.pdf (publisher's version ) (Open Access

Acute temperature elevation in tap and Rhine water affects skin and gill epithelia, hydromineral balance, and gill Na+/K+-ATPase activity of brown trout (Salmo trutta) smolts

Contains fulltext : 14091.pdf ( ) (Open Access

The Relationship between the Ionic Composition of the Environment and the Secretory Activity of the Endocrine Cell Types of Stannius Corpuscles in the Teleost Gasterosteus aculeatus

The corpuscles of Stannius of threespined sticklebacks contain two glandular cell types of presumed endocrine nature. To elucidate the function of both cell types the secretory activity of the cells was studied in fully adapted seawater and freshwater fishes and in specimens transferred from sea water to fresh water or adapted to media of various ionic composition. The secretory activity was established, in tissue sections and freeze-etch replicas, by estimating the volume of the nuclei, the density of the nuclear pores, and the frequency of exocytotic phenomena. The type-1 cells, ultrastructurally comparable to the predominant or only cell type described in many other teleosts, are more active in sea water than in fresh water. The activity of the type-2 cells, whose ultrastructural appearance is known only for salmonids and eels, is higher in fresh water. Transfer of seawater fishes to fresh water results in reduction of type-1 cells and activation of type-2 cells. The factors responsible for these changes were analyzed by exposure of fishes to solutions of various salts in fresh water and to artificial sea water with a reduced content of one of its components. The high activity of type-1 cells in sea water proved to be related to the high calcium content of this medium. These cells probably produce a substance comparable to hypocalcin, the endocrine factor isolated from the Stannius corpuscles of some other teleost species. The high activity of type-2 cells in fresh water appeared to be connected with the low sodium and potassium levels of this medium. Type-2 cells possibly produce a hitherto unknown hormone involved in the control of sodium and/or potassium metabolism