The Evolution of the Vertebrate Neurohypophysial Hormones in Relation to the Genetic Code

SUMMARY Active neurohypophysial principles were separated from pituitary glands from a primitive actinopterygian, Polypterus senegalis, and the African lungfish, Protopterus aethiopicus. Both species appeared to possess arginine vasotocin (8-arginine oxytocin) and a more nearly neutral principle resembling oxytocin. In the case of Polypterus the neutral principle was pharmacologically indistinguishable from isotocin (4-serine, 8-isoleucine oxytocin). When subjected to partition chromatography on a Sephadex column the neutral Polypterus principle appeared homogeneous and emerged at an elution volume identical with that of isotocin. The neutral principle from Protopterus neurohypophysial extracts resembled mesotocin (8-isoleucine oxytocin) pharmacologically. On partition chromatography it appeared to be a single peptide with mobility comparable to that of mesotocin. No evidence was found for the presence of oxytocin despite earlier reports that this principle occurs in Protopterus and in the South American lungfish, Lepidosiren. From these studies it appears that Polypterus has neurohypophysial principles (arginine vasotocin and isotocin) identical with those found among higher actinopterygians, the Holostei and Teleostei. On the other hand, Protopterus principles resemble those found among Amphibia (arginine vasotocin, mesotocin, and possibly oxytocin).

Section: Partition Chromatographymentioning

confidence: 99%

The Active Neurohypophysial Principles of Two Primitive Bony Fishes, the Bichir (Polypterus Senegalis) and the African Lungfish (Protopterus Aethiopicus)

Sawyer¹

1969

“…For example, questions as to whether oxytocin or [8-isoleucine]-oxytocin is evolutionarily older and whether oxytocin has persisted in an unbroken line since it originated would become unanswerable if both hormones are common variants, since both can be derived from vasotocin and from each other by single base changes (Vliegenthart & Versteeg, 1967). Evolution would then be seen as a dynamic process rather than an orderly, linear progression (Acher et al 1969).…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, various attempts have been made to trace the evolution of structure of the neurohypophysial hormones (Munsick, 1966;Sawyer, 1966;Geshwind, 1967;Heller & Spickett, 1967;Vliegenthart & Versteeg, 1967; Pickering & Heller, 1969;Acher, Chauvet & Chauvet, 1969, in the same way as deductions have been made concerning the evolution of larger polypeptides, for example, the globins and the cytochromes (see Dayhoff & Eck, 1968). Granted the * Present address: Department of Zoology, University of Edinburgh, West Mains Road, Edinburgh, EH 9 3JT.…”

Section: Introductionmentioning

confidence: 99%

Genetic Variation in the Neurohypophysial Hormones of the Mouse, Mus Musculus

Stewart¹

1971

The possibility of genetic variation in the amino acid composition of neurohypophysial hormones of the mouse was investigated. Acetic acid extracts from acetone-dried neurohypophyses from six strains of mice were subjected to thin-layer chromatography. Extracts from two strains were tested for natriferic potency on a toad bladder preparation. Extracts from three strains of mice were purified on a carboxymethylcellulose column, and the amino acid composition determined by paper electrophoresis at pH2.All six strains of mice were found to elaborate an oxytocic principle with the chromatographic properties of oxytocin. All results were compatible with the view that five of the strains elaborate the usual mammalian vasopressin, [8-arginine]-vasopressin. However, chromatography, natriferic assays and analyses of amino acid composition indicated that the Peru strain of mice elaborated [8-lysine]-vasopressin. These mice would be the first mammals outside the Suina which possess this hormone, and the difference between the strains of mice is almost certainly genetic in origin. The significance of genetic variation within a species in the structure of a hormone is discussed in terms of its physiological and evolutionary consequences.

“…During the past 10 years several evolutionary schemes have been proposed (for recent reviews see: Acher, Chauvet, Chauvet & Crepy, 1965;Heller & Spickett, 1967;Vliegenthart & Versteeg, 1967;Sawyer, 1968;Heller & Pickering, 1969) but we feel justified in proposing yet another to account both for the occurrence of oxytocin in Hydrolagus and for the discovery that this hormone may exist along with [8-isoleucine]-oxytocin in certain lungfishes (Sawyer & van Dyke, 1963;Pickering & McWatters, 1966), amphibians (Munsick, 1966) and reptiles (Pickering, 1967). During the past 10 years several evolutionary schemes have been proposed (for recent reviews see: Acher, Chauvet, Chauvet & Crepy, 1965;Heller & Spickett, 1967;Vliegenthart & Versteeg, 1967;Sawyer, 1968;Heller & Pickering, 1969) but we feel justified in proposing yet another to account both for the occurrence of oxytocin in Hydrolagus and for the discovery that this hormone may exist along with [8-isoleucine]-oxytocin in certain lungfishes (Sawyer & van Dyke, 1963;Pickering & McWatters, 1966), amphibians (Munsick, 1966) and reptiles (Pickering, 1967).…”

Section: Discussionmentioning

confidence: 99%

Oxytocin as a Neurohypophysial Hormone in the Holocephalian Elasmobranch Fish, Hydrolagus Collei

Pickering¹,

Heller²

1969

Two peptides with uterotonic activity have been isolated from the pituitary gland of a holocephalian elasmobranch fish: Hydrolagus collei. One of them had an amino acid composition compatible with that of oxytocin itself, and also had the pharmacological properties of this hormone. The other peptide which was present in much smaller amounts was basic by chromatography and had the pharmacological characteristics of [8-arginine]\x=req-\ oxytocin. It was not completely purified because of the small amount available, but its amino acid composition was in accord with that of vasotocin. The implications of the presence of oxytocin in such a primitive fish on the phylogeny, and hence probably the evolution, of neurohypophysial hormones are discussed.