The role of nutrition and endocrine activity in the development of eggs inCulex fatigans

Zusammenfassung Begattete weiblicheCulex fatigans legen ihre Eier 72 h nach einem Blutmahl, wenn die Aktivität der medianen neurosekretorischen (MNSC) Zellen am höchsten ist. Die Corpora allata (CA) erreichen 24 h nach dieser Mahlzeit ihre höchste Aktivität und es wird daraus geschlossen, dass das Hormon der CA Eireifung und die Sekrete dér MNSC die Eiablage bewirken.     

The role of synapsins in neuronal development

The synapsins, the first identified synaptic vesicle-specific proteins, are phosphorylated on multiple sites by a number of protein kinases and are involved in neurite outgrowth and synapse formation as well as in synaptic transmission. In mammals, the synapsin family consists of at least 10 isoforms encoded by 3 distinct genes and composed by a mosaic of conserved and variable domains. The synapsins are highly conserved evolutionarily, and orthologues have been found in invertebrates and lower vertebrates. Within nerve terminals, synapsins are implicated in multiple interactions with presynaptic proteins and the actin cytoskeleton. Via these interactions, synapsins control several mechanisms important for neuronal homeostasis. In this review, we describe the main functional features of the synapsins, in relation to the complex role played by these phosphoproteins in neuronal development.     

The role of calcium in aggregation and development ofDictyostelium

Changes in cytosolic Ca²⁺ play an important role in a wide array of cell types and the control of its concentration depends upon the interplay of many cellular constituents. Resting cells maintain cytosolic calcium ([Ca²⁺]_i) at a low level in the face of steep gradients of extracellular and sequestered Ca²⁺. Many different signals can provoke the opening of calcium channels in the plasma membrane or in intracellular compartments and cause rapid influx of Ca²⁺ into the cytosol and elevation of [Ca²⁺]_i. After such stimulation Ca²⁺ ATPases located in the plasma membrane and in the membranes of intracellular stores rapidly return [Ca²⁺]_i to its basal level. Such responses to elevation of [Ca²⁺]_i are a part of an important signal transduction mechanism that uses calcium (often via the binding protein calmodulin) to mediate a variety of cellular actions responsive to outside influences.     

The role of the autonomic nervous system in mediating pancreatic endocrine responses to arginine in the calf

The release of insulin which occurred in response to arginine, in the conscious calf, differed from that which occurs in response to glucose in that it was not significantly affected by either adrenergic or muscarinic blocking agents. Release of pancreatic glucagon was reduced by pretreatment with phentolamine.     

The role of the autonomic nervous system in mediating pancreatic endocrine responses to arginine in the calf

Summary The release of insulin which occurred in response to arginine, in the conscious calf, differed from that which occurs in response to glucose in that it was not significantly affected by either adrenergic or muscarinic blocking agents. Release of pancreatic glucagon was reduced by pretreatment with phentolamine.This work was supported by the British Diabetic Association. It is a particular pleasure to acknowledge the skilled assistance provided by Messrs P. M. M. Bircham and G. P. McGregor.     

The heuristic role of mathematics in the initial development of superconductivity theory

During the first twenty-four years after the discovery of superconductivity many attempts to derive an adequate theory failed, mainly because the problem was not formulated quite correctly. In this paper we investigate certain questions related to the heuristic role of mathematics in the appropriate formulation of the problem that had to be solved and the development of a theory which was hindered by theoretical superstitions.     

The development of the amylase activity in blood and its behaviour in the amniotic fluid in rats

Zusammenfassung Die Amylaseaktivität im Blut von Wistarratten steigt bis zum Ende der Säugeperiode an. In der Amnionflüssigkeit fehlt sie zunächst, nimmt oberhalb eines Fötalgewichtes von 2 g auf ein Vielfaches der Blutwerte zu und fällt mit schwindender Amnionflüssigkeit am Ende der Gravidität stark ab.     

A possible endocrine mechanism for inducing diapause in the eggs ofAdelphocoris lineolatus (Goeze) (Hemiptera: Miridae)

Résumé Adelphocoris lineolatus (Goeze) est un Insecte bivoltin en Minnesota, mais qui n'a qu'une seule génération annuelle en Saskatchewan. L'induction de la diapause dans l'uf semble être influencée en partie par la photopériode à laquelle est soumise la femelle. Dans le cas des femelles adultes destinées à pondre les ufs diapauses, les cellules neurosécrétoires du type B du ganglion thoraco-abdominal, pendant les derniers deux tiers de la période précédant la ponte, produisent et déchargent un colloïde neurosécrétoire. Quant à la première génération de la population de Minnesota qui produit les ufs non-diapauses, ces cellules ne montrent aucun caractère d'activité sécrétoire.

---

---

Contribution No. 242, Research Station, Canada Agriculture, Saskatoon, Saskatchewan.     

The endocrine role for chromogranin A: A prohormone for peptides with regulatory properties

Chromogranin A (CgA) belongs to the granin family of uniquely acidic secretory proteins co-stored and co-secreted with other hormones and peptides in elements of the diffuse neuroendocrine system. The granins arise from different genes and are characterized by numerous sites for post-translational cleavage into shorter peptides with postulated regulatory properties. This review is directed towards endocrine aspects of CgA and its biologically active peptides. There is ample evidence from in vitro studies of distinct effects and targets for three CgA-derived peptides, vasostatin-I, pancreastatin and catestatin. Endocrine regulations are indicated from in vivo studies, consistent with the postulated prohormone function of CgA for peptides with regulatory properties. Most of the effects fit into patterns of direct or indirect, inhibitory modulations of major functions, implicating CgA peptides in regulation of calcium and glucose metabolism, cardiovascular functions, gastrointestinal motility and nociception, tissue repair, inflammatory responses and as host defense peptides in the first phase of microbial invasions. Received 1 June 2007; received after revision 11 July 2007; accepted 12 July 2007     

The role of volume expansion,of prostaglandins and catecholamines in the development of acute renal failure

Summary A single injection either of isotonic or hypertonic saline solutions protected rats against acute renal failure (ARF) induced with glycerol. This protection was accompanied by increased urinary prostaglandin E (PGE) concentration. On the contrary, a single s.c. injection either of hypotonic saline or isotonic glucose solution, which did not increase urinary PGE concentration, or depletion of the endogenous catecholamines, using reserpine, did not protect the animals against acute renal failure.The authors wish to thank Miss Sylvie Bompis and Miss Ermione-Loukia Ghikas for their technical assistance and Mr Richard Irvine B.A. for his help with the English.     

The endocrine nature of the paraganglia of man

Summary Brightly fluorescent paraganglia were found in the retroperitoneal tissue of adult man. The histofluorescence properties of the paraganglia indicate the presence of tryptophyl peptides, which might be of endocrine importance.     

The endocrine nature of the paranganglia of man

Brightly fluorescent paraganglia were found in the retroperitoneal tissue of adult man. The histofluorescence properties of the paraganglia indicate the presence of tryptophyl peptides, which might be of endocrine importance.