Roger Acher

The neurohypophysial hormones of the amphibians: Comparison of the hormones of Rana esculenta and Xenopus laevis☆

Abstract Neurohypophysial extracts from frogs ( Rana esculenta ) and Xenopus ( Xenopus laevis ) have been chromatographed on microcolumns of Amberlite CG-50. In each case two hormones have ben found. Xenopus -active principles are very similar to those of Rana esculenta in their chromatographic and pharmacologic properties. The posterior pituitary of Xenopus laevis contains a hormone which, when assayed for three biological activities (oxytocie, pressor, and hydro-osmotic assays), seems identical to arginine-vasotocin which has been chemically characterized from frog glands.

The neurohypophyseal hormones of reptiles: Comparison of the viper, cobra, and elaphe active principles

The neurohypophyseal hormones of three species of snakes, the viper Viperaaspis (Viperidae), the cobra Naja naja (Elapidae), and the elaphe Elaphe quadrivirgata (Colubridae) have been isolated. Mesotocin (Iles-oxytocin) and arginine vasotocin (Args-oxytocin) have been chemically identified. The two snake hormones are similar to those of frog or toad species and no variation seems to have occurred during the amphibian-reptile transition.

Molecular evolution of neurohypophysial hormones: Comparison of the active principles of three bony fishes

Abstract Isotocin (Ser 4 -Ile 8 -oxytocin) and arginine vasotocin (Arg 8 -oxytocin), have been chemically identified in cod, tuna, and mackerel. So far the same neurohypophysial hormones have been found in seven species of teleost fish belonging to the families: Gadidae, Scombridae, and Cyprinidae.

Les hormones neurohypophysaires des amphibiens: Isolement et caractérisation de la mésotocine et de la vasotocine chez le crapaud (Bufo bufo)

Resume Deux hormones neurohypophysaires du crapaud Bufo bufo ont ete isolees en utilisant un procede en trois etapes: adsorption des principes actifs sur la neurophysine et precipitation au moyen de chlorure de sodium, dissociation du complexe par lacide trichloroacetique qui elimine la proteine-support, isolement des deux peptides par chromatoelectrophorese sur papier. Chaque peptide a ete caracterise par ses propriet e s physico-chimiques et pharmacologiques ainsi que par sa composition en acides amines. Les deux hormones sont identiques respectivement a la mesotocine (Ile 8 -ocytocine) et a la vasotocine (Arg 8 -ocytocine) anterieurement isolees de la posthypophyse de la grenouille Rana esculenta .

Reptilian neurohypophyseal hormones: the active peptides of a Saurian, Iguana iguana

Abstract The neurohypophyseal hormones of a saurian, Iguana iguana , have been isolated. Mesotocin ([8-isoleucine]oxytocin) has been characterized by its amino acid composition and biological properties. Arginine vasotocin ([8-arginine]oxytocin) has been identified from its chromatoelectrophoretic migrations and pharmacological activities. These peptides have been demonstrated previously in snakes so the Ophidia and the Sauria , which belong to the same order, Squamata, seem to have the same neurohypophyseal hormones.

Évolution des hormones neurohypophysaires : isolement des principes actifs du lapin et du rat

Summary The neurohypophysial hormones of one species of Lagomorpha, the rabbit, and one species of Rodentia, the rat, have been isolated and characterized by amino acid composition, chromatographic and electrophoretic migrations and pharmacological properties. Oxytocin and arginine vasopressin have been identified in both cases. The same neurohypophysial hormones have so far been found in seven species belonging to six orders of eutherian mammals : Primates, Cetacea, Lagomorpha, Rodentia, Perissodactyla and Artiodactyla. In an eighth species belonging to Artiodactyla, the pig, lysine vasopressin replaces arginine vasopressin. In contrast the non-mammalian tetrapods (birds, reptiles, amphibians) have two different hormones, mesotocin (Ile 8 -oxytocin) and arginine vasotocin (Arg 8 -oxytocin) so that a double change has probably occurred somewhere between mammalian reptiles or primitive mammals and the present-day eutherian species.

Biological properties of synthetic Ser 4 -Arg 8 -oxytocin (Ile 3 -Ser 4 -Arginine vasopressin): Role of the residue No. 4 in the hormone-pressor receptor interaction

Les propriétés pharmacologiques de la Ser4-Arg8-ocytocine (Ser4-vasotocine) synthétique ont été étudiées. La substitution en position 4 de la glutamine par la sérine diminue considérablement lactivité pressique de la vasotocine, ce qui montre limportance de cette position dans les interactions entre les hormones neurohypophysaires et le récepteur vasopressique.

Evolution of Proteins: From Gene Determinism to Cellular Integration

The discovery that eukaryotic genes coding for proteins are usually split into several pieces has ruined the simple and convenient concept “one gene — one protein.” It appears now that most eukaryotic proteins are composite systems, not only from the functional viewpoint because of their specialized domains (Richardson, 1981), but also from the biosynthetic aspect since each protein is the product of several separate coding sequences (exons) within the gene. It is not yet known however whether the relationship “one exon-one domain” will be the new dogma. Because genes are the Dei ex machina of evolution, the destruction of their individuality triggers a revolution in biology, as did the split of the atom in chemistry. The present apparent chaos is due to our ignorance of the regulatory mechanisms involved in the genome working.

Ontogeny and phylogeny of neuropeptides: Protein precursors and enzymic processing

Abstract Neurohypophysial hormones are nonapeptides derived from precursors containing two or three domains, namely the hormonal moiety, a small protein, neurophysin (93/95 residues) and occasionally a glycopeptide, copeptin (39 residues). Enzymic processing of the precursors is very fast and separate domains are usually found in neurohypophysis. These fragments can be used on one hand to trace two phylogenetic lineages in vertebrates, on the other hand to follow expression of the precursor genes during the early stages of development. Regarding the hormonal domains, whereas mammalian species possess virtually always vasopressin and oxytocin, nonmammalian tetrapods have vasotocin ([Ile3]-vasopressin) and mesotocin ([Ile8]-oxytocin). Concerning the neurophysin domains, the two types MSEL-neurophysin (vasopressin-associated) and VLDV-neurophysin (oxytocin-associated) identified in mammals, have been also detected in nonmammalian tetrapods suggesting the association of MSEL-neurophysin with vasotocin and VLDV-neurophysin with mesotocin. About copeptin, recognition in lower vertebrates is difficult, likely because of a high number of substitutions. The three distinct domains correspond roughly to separate coding regions within the genes and could therefore have had autonomous evolutionary histories. Studies carried out with bovine fetus at the ages of 3 and 7 months reveal the same neuropeptides as those identified in the adult, but vasopressin gene is expressed 3 and 4 times more than oxytocin gene whereas in the adult both genes are roughly equally productive. This research fails, however, to identify vasotocin in fetus and to demonstrate a molecular recapitulation of neurohypophysial hormones, as previously suggested on the basis of pharmacological and immunological data.