Phylogeny of the Neurohypophysial Hormones

Abstract

The neurohypophysial hormones of a chondrostean, the sturgeon (Acipenser sp.), have been purified by adsorption onto neurophysin, dissociation of the complex hormone-protein by trichloroacetic acid precipitation and isolation of active peptides, from the supernatant solution, by paper chromatoelectrophoresis.Arginine vasotocin has been characterized by amino acid composition, chromatographic and electrophoretic migrations and pharmacological properties as well. The amount of arginine vasotocin (about 50 nmol per g pituitary powder) is intermediary between those found for bony fishes (about 1000 nmol/g) and cartilaginous fishes (about 5 nmol/g).A second hormone, which can be classified in the oxytocin-like type by its electrophoretic migration and its pharmacological properties, has been disclosed. The very weak amount did not allow chemical identification. However the chromatographic behaviour and the pharmacological ''profile" indicate that this hormone differs from the six known oxytocin-like peptides.The sturgeons belong to the order Chondrostei and are classified by Rothschild [l] in the sub-class Palaeopterygii of the bony fishes. The rare living species of this primitive sub-class might have hormones different from those of the current bony fishes Neopterygii. If so, they could be regarded as evolutionary precursors. Investigations have already been carried out on Polypterus, an African fish belonging to the only other order of the sub-class, the Cladistia. Isotocin MATERIALS AND METHODS GlandsSturgeon Table I. [2,3]. The pressor activity is 10-fold higher than that found for cartilaginous fishes but about 10-fold lower than that of bony fishes. As found previously [4], the ratio of pressor activity to oxytocic activity is higher than 1, a ratio rather unusual in bony fishes. Bioassays Purification of HormonesPurification was carried out with Russian batches which were somewhat more active. Four assays have been carried out first with 150mg (Russian batch 1966), then with 60 mg, 1 g and 4 g (Russian batch 1967).Eur. J. Biochem. 40 (1973)

Morphofunctional remodelling of the osmoregulatory system in starred sturgeon Acipenser stellatus (Acipenseridae) during transition from hyperosmotic to hypoosmotic regulation

“…In reply to saline exposure in teleosts (after the transfer of fish from fresh water to marine environment) the removal of neurosecretory granules into axons was also noted (Jasinski et al, 1967). As is known, the hypothalamic preoptic nucleus of acipenserids, as well as other vertebrates (excluding mammals) produces AVT and oxytocin like hormone (isotocin), which differs by its unique structure from the similar hormone of other fish (Achez et al, 1973).…”

Mesotocin and vasotocin, two neurohypophysial hormones in the ostrich, Struthio camelus

“…(Australian marsupials) were isolated (5), as well as those from a primitive fish, the sturgeon (6), and a cartilaginous fish, the spiny dogfish (7). The presently known hormones have a common molecular pattern in that they consist of 9 amino acid residues with a disulfide bridge between residues 1 and 6 (4).…”