Secretogranin II: Relative Amounts and Processing to Secretoneurin in Various Rat Tissues

Abstract: Secretoneurin is a 33-amino-acid peptide produced in vivo from secretogranin II. An antiserum raised against this peptide recognizes both the free peptide and its precursors. By HPLC and radioimmunoassay we characterized the immunoreactive molecules and determined the levels of immunoreactivity in various rat organs. In adrenal medulla and to a lesser degree in the anterior pituitary processing of secretogranin II to secretoneurin was very limited, whereas in all other organs studied (brain, intestine, endocrine pancreas, thyroid gland, and posterior pituitary) a high degree of processing was apparent. Thus, practically all of the immunoreactivity was present as free secretoneurin. This was also true for serum. When the total amount of secretoneurin immunoreactivity was calculated for the various organs, the largest pools in descending order were in the intestine, CNS, anterior pituitary, pancreas, and adrenal gland. This makes it likely that secretoneurin in serum is mainly derived from the intestine. The high degree of processing of secretogranin II in most organs is consistent with the concept that this protein acts as a precursor of a functional peptide, i.e., secretoneurin.     

Communication in the migratory termite-hunting ant Pachycondyla (= Termitopone) marginata (Formicidae, Ponerinae)

The Neotropical species Pachycondyla marginata conducts well-organized predatory raids on the termite species Neocapritermes opacus and frequently emigrates to new nest sites. During both activities the ants employ chemical trail communication. The trail pheromone orginates from the pygidial gland. Among the substances identified in the pygidial gland secretions, only citronellal was effective as a trail pheromone. Isopulegol elicited an increase in locomotory activity in the ants and may function as a synergist recruitment signal. The chemical signal is enhanced by a shaking display performed by the recruiting ant.     

Volume-sensitive taurine efflux from mammary tissue is not obliged to utilize volume-activated anion channels

Cell-swelling, induced by a hyposmotic shock, activates the release of taurine from lactating rat mammary tissue expiants. The degree of stimulation of taurine efflux was dependent upon the extent of cell-swelling. Volume-sensitive taurine release was attenuated by the anion transport inhibitors NPPB, DIOA, DIDS, niflumate, flufenamate, mefenamate and diiodosalicylate but not by salicylate. Cell-swelling, following a hyposmotic challenge, did not increase the unidirectional efflux of radiolabelled I^– or D-asparate from mammary tissue expiants. The results suggest that although mammary tissue expresses a volume-sensitive amino acid transport system which is inhibited by anion transport blockers the pathway has no identity with volume-activated anion channels.     

Cell-specific mechanisms of estrogen receptor in the pituitary gland

Analysis of the mechanism of action of estrogen receptor shows protein and mRNA polymorphism within distinct pituitary receptor-positive cells. The lactotropes exhibit unique properties in these mechanisms that distinguish them from gonadotropes. Therefore, this cell type constitutes an especially interesting model in the male as well as in the female for estrogen receptor studies.Abbreviations PRL prolactin - E2 estradiol - ER estrogen receptor - GnRH gonadotropin releasing hormone - PMSG pugnant mare serum gonadotropin     

Effects of cytochalasin D on the distribution of actin and ACTH-induced steroidogenesis in cultured embryonic adrenal gland cells from the Pekin duck (Anas platyrhynchos)

Cultured steroidogenic cells derived from the adrenal glands of duck embryos were used to study changes in the distribution of actin associated with the corticotropic responsiveness. Actin-containing components were identified by rhodamine-phalloidin staining. The actin in most of the unstimulated cells occurred as stress fibers that either ran parallel throughout the cell or were present as domains of parallel fibers at angles to one another. When incubated in Krebs-Henseleit buffer containing 1–24 ACTH, the cells released approximately equal amounts of corticosterone and aldosterone. Incubation of the cells in buffer containing cytochalasin D caused the cells to lose their stress fibers, and the actin became distributed at the periphery in what appeared to be fragments of stress fibers and clumps of fibrous material in the central cytoplasm. Although cytochalasin D did not affect the basal output of corticosterone and aldosterone, the 1–24 ACTH-induced rates of both hormones were suppressed significantly. After the cells had been washed in unadulterated buffer, the normal distribution of actin stress fibers was restored and the cells responded normally when incubated in buffer containing 1–24 ACTH. These results suggest that the actin components of the cytoskeleton are important determinants of corticotropin-induced steroidogenic responsiveness.     

Immunocytochemical study of seminal γ-glutamyltransferase using monoclonal antibodies

We produced three monoclonal antibodies, SG1, SG2 and SG3, specific for human seminal -glutamyltransferase when characterized by enzyme-linked immunosorbent assay and immunoblotting. Seminal -glutamyltransferase was localized, by immunostaining, to the epithelial cells of the ductus epididymidis, seminal vesicle and prostate gland with SG1, those of the prostate gland with SG2, and those of the seminal vesicle with SG3. Rabbit polyclonal anti-seminal -glutamyltransferase serum reacted with the proximal convolution of the kidney and the bile capillaries of the liver, and with the epithelial cells of the reproductive organs. However, immunoreactivity was not observed in the kidney or liver with the monoclonal antibodies. Thus, these monoclonal antibodies are probably all specific to seminal -glutamyltransferase but recognize different epitopes.