Antibodies specific for chromogranin A, B or C have been used to detect immunohistochemically these three anionic proteins. Pancreatic A, B and PP cells, gut argentaffin EC, argyrophil ECL and gastrin G cells, thyroid C cells, parathyroid cells, adrenal medullary cells, pituitary TSH, FSH and LH cells as well as some axons of visceral nerves have been found to react with chromogranin A antibodies. Pancreatic A, gut EC and G, adrenal medullary and pituitary cells as well as some gut nerve fibers showed chromogranin B immunoreactivity. Chromogranin C immunoreactivity has been detected in pancreatic A, pyloric D1, intestinal L, thyroid C, adrenal medullary and pituitary cells, as well as in some gut neurons and nerve fibers. No crossreactivity has been found in immunohistochemical tests between chromogranins A, B or C and costored monoamines or peptide hormones/prohormones, from which chromogranins can be separated by selective extraction during fixation. On both morphological and chemical grounds a relationship seems to exist between chromogranin A and Grimelius' argyrophilia. Sialooligosaccharide chains of chromogranin A and, possibly, chromogranins' phosphoserine/phosphothreonine groups, seem to interact with guanidyl, amino, and/or imidazole groups of non-chromogranin components to form silver complexing sites accounting for granules' argyrophilia, which can be removed or blocked without affecting chromogranin immunoreactivities. The abundant anionic groups of the three proteins should contribute substantially to granules' basophilia, the partly "masked" pattern of which supports the existence of a close interaction of such groups with other components of secretory granules, including monoamines and peptide hormones or prohormones. Chromogranins could play a rôle in hormone postranslational biosynthesis and intragranular packaging.

An Italian family suffering from a novel hereditary disease, i.e. hypofihrinogenemia connected with hepatic storage of fibrinogen, has been identified. A similar disorder has previously been described in two German families. The discovery originated from the finding of a massive hepatic storage of fibrinogen in a liver biopsy specimen from a 65 years old female who during a laparotomy unexpectedly turned out to display cirrhosis. Identification of the stored material as fibrinogen was carried out by specific immunostaining applied on both light and electron-microscopic level. The stored fibrinogen appeared in the form of eosinophilic, pale, irregularly shaped inclusions within the cytoplasm of the hepatocytes. E.M. showed that the inclusions correspond to dilated cisternae of the RER filled by densely packed, curved, tubular structures arranged in a fingerprint-like fashion. Similar features of fibrinogen storage were not detected in any of 500 consecutive liver biopsy specimens examined for this purpose by appropriate techniques. Plasma fibrinogen (thrombin clottable fibrinogen) was found to be 35 mg/dl (n.v. 100-300 mg/dl), and remained persistently very low (20-1-0 mg/dl) over a follow-up period of two years. The immunoreactive fibrinogen was found to be two-three times as high as the clottable. The patient showed no clinical defect of hemostasis or impaired wound healing. Eight out of 19 family members also had persistently low plasma fibrinogen levels (U5-80 mg/dl) over the same follow-up period. Hypofibrinogenemia with hepatic storage of fibrinogen seems to represent a further endoplasmic reticulum storage disease in addition to a-1-antitrypsin deficiency, the plasma deficiency being due to defective secretion of the protein from the hepatocytes. A genetically determined molecular abnormality may be responsible for the defective intracellular transport and subsequent storage at the primary site of protein synthesis, the RER. Hepatic storage of fibrinogen is likely to predispose to development of liver cirrhosis, but neither to defective hemostasis nor impaired wound healing.

Peptide synthetases are large enzymatic complexes that catalyze the synthesis of biologically active peptides in microorganisms and fungi and typically have an unusual structure and sequence. Peptide synthetases have recently been engineered to modify the substrate specificity to produce peptides of a new sequence. In this study we show that surfactin synthetase can also be modified by moving the carboxyl-terminal intrinsic thioesterase region to the end of the internal amino acid binding domains, thus generating strains that produce new truncated peptides of the predicted sequence. Omission of the thioesterase domain results in nonproducing strains, thus showing the essential role of this region and the possibility of obtaining peptides of different lengths by genetic engineering. Secretion of the peptides depends on the presence of a functional sfp gene.Two mechanisms for the biosynthesis of peptides are known to exist in bacteria and fungi, ribosomal synthesis and production by peptide synthetases. These are large enzymatic complexes responsible for the synthesis of hundreds of types of peptides, some of which have immunoactive, antibiotic, antifungal, or surfactant properties. Whereas polypeptides produced by ribosomal synthesis typically contain only the amino acids directly specified by the triplets of the genetic code, peptides built on synthetases often contain unusual amino or hydroxy acids as building blocks that are not present in proteins. The amino acids can be modified by peptide synthetases either through methylation, hydroxylation, or enantiomerization. The peptides are typically short (up to about 20 residues) and can be linear, circular, or branched (1, 2). Peptide synthesis proceeds by the "multiple carrier thiotemplate mechanism" (3, 4), and many of the details of these systems remain to be investigated experimentally. According to this mechanism each domain recognizes a specific amino (or hydroxy) acid that is covalently bound to the cofactor via a thioester bond after activation to the corresponding acyladenylate derivative. The growth of the polypeptide chain thus occurs through a series of thioester bond cleavages and the simultaneous formation of amide or ester bonds in the peptide. At the end of synthesis of each peptide, the chain is thought to be released from the enzyme by a thioesterase (TE) 1 activity encoded in the synthetase gene (1). Peptide synthetases are interesting not only from a scientific and evolutionary point of view but also for their biotechnological potential. Many enzymatically synthesized peptides are in fact biologically active, and some of them are industrially produced, among which are cyclosporins, surfactin, and fungicides. A growing number of laboratories are involved in applied research projects focused on the isolation and characterization of new peptide synthetases and on the genetic manipulation of peptide synthetase genes to optimize peptide production and to genetically modify the sequence of the peptides produced. In fact, the structural organization...

The regional distribution of neuropeptide Y (NPY) immunoreactivity and receptor binding was studied in the porcine CNS. The highest amounts of immunoreactive NPY were found in the hypothalamus, septum pellucidum, gyrus cinguli, cortex frontalis, parietalis, and piriformis, corpus amygdaloideum, and bulbus olfactorius (200-1,000 pmol/g wet weight). In the cortex temporalis and occipitalis, striatum, hippocampus, tractus olfactorius, corpus mamillare, thalamus, and globus pallidus, the NPY content was 50-200 pmol/g wet weight, whereas the striatum, colliculi, substantia nigra, cerebellum, pons, medulla oblongata, and medulla spinalis contained less than 50 pmol/g wet weight. The receptor binding of NPY was highest in the hippocampus, corpus fornicis, corpus amygdaloideum, nucleus accumbens, and neurohypophysis, with a range of 1.0-5.87 pmol/mg of protein. Intermediate binding (0.5-1.0 pmol/mg of protein) was found in the septum pellucidum, columna fornicis, corpus mamillare, cortex piriformis, gyrus cinguli, striatum, substantia grisea centralis, substantia nigra, and cerebellum. In the corpus callosum, basal ganglia, corpus pineale, colliculi, corpus geniculatum mediale, nucleus ruber, pons, medulla oblongata, and medulla spinalis, receptor binding of NPY was detectable but less than 0.5 pmol/mg of protein. No binding was observed in the bulbus and tractus olfactorius and adenohypophysis. In conclusion, immunoreactive NPY and its receptors are widespread in the porcine CNS, with predominant location in the limbic system, olfactory system, hypothalamoneurohypophysial tract, corpus striatum, and cerebral cortex.

No abstract