Isolation of a single component of fish insulin from a bonito-tuna-swordfish insulin mixture and its complete amino-acid sequence

cDNAs from neurosecretory cells of brains of Locusta migratoria (Insecta, Orthoptera) encoding a novel member of the superfamily of insulins

From neurohaemal lobes of corpora cardiaca of Locusta migratoria a 5-kDa peptide has been isolated and its sequence established [see the accompanying paper, by Hietter et al. (1990) Eur. J. Biochem. 187, 241-247]. We have designed oligonucleotide probes from the peptide sequence of this molecule and screened a library prepared from mRNA of the neurosecretory cell region of the brain of this insect. Several positive cDNAs were isolated, the combined nucleotide sequences of which predict a large precursor of 145 residues (15770 Da) containing the newly isolated 5-kDa peptide. The peptide is flanked by regions homologous to the A and B chains of the superfamily of insulins. The overall organization of the precursor is as follows: signal peptide/domain homologous to the B chain of insulins/C (connecting)-peptide (corresponding to the newly isolated 5-kDa peptide)/domain homologous to the A chain of insulins. The numbers and relative positions of the cysteines of the Locusta peptide are equivalent to those of the other members of the insulin superfamily and most of the hydrophobic core residues are conserved.

Immunocytochemical localization of hormone-producing cells within the pancreatic islets of the rainbow trout (Salmo gairdneri)

A histological study of the pancreatic islets in rainbow trout, Salmo gairdneri, was undertaken in which polypeptide hormones-producing cells were localized, using immunocytochemical staining techniques. Four different cell-types were identified in this manner. These were the insulin, somatostatin, pancreatic polypeptide and glucagon/gastric inhibitory polypeptide (GIP) cells. The glucagon/GIP cell was designated thus as antisera to both hormones cross-reacted with a common population of cells. A fifth cell-type, commonly referred to as a clear cell, was also identified although its secretory product is as yet undetermined. These functional cell types were compared to the standard tinctorial properties of pancreatic endocrine cells. The relationships of the various cell types with each other was also observed.