Glycoprotein secretion in the hypothalamo-neurohypophyseal system of the rat

Summary Although the secretory products of the hypothalamoneurohypophyseal system are not glycoproteins, synthesis and migration of these macromolecules occur within its secretory neurons. After being labeled with ³H-fucose in the Golgi apparatus, newly synthesized glycoproteins migrate to secretion granules, lysosomes and the plasma membrane of the secretory neurons, as demonstrated by quantitative electron-microscopic radioautography. Secretion granules bearing newly synthesized glycoproteins migrate to the pars nervosa, the labeling pattern of which was studied in rats killed from 4 h to 14 days after the isotope injection. Most of the silver grains were observed to overly the secretory axons. Labeling of pituicytes was negligible and the number of silver grains over the perivascular spaces was about 10% of the total at certain postinjection intervals. In the secretory axons, most of the silver grains were seen to overly the secretion granules. The proportion of silver grains over the different portions of the secretory axons changed with time. At the longer intervals, the percentage of silver grains increased over the nerve swellings (including Herring bodies) and decreased concomitantly in the undilated portions of the axons and in the nerve endings. This labeling pattern conforms with observations on the secretion products. Water deprivation increased the release of neurosecretion as well as glycoproteins from the pars nervosa. However, glycoproteins inside the Herring bodies were not easily releasible. There was a parallel decrease in the amount of secretion granules and ³H-fucose-labeled glycoproteins indicating that the glycoproteins are predominantly a constituent of the granule content. Some newly synthesized glycoproteins were probably also used in the renewal of the axonal membrane. The labeling of smooth vesicles in nerve endings was discussed. In conclusion, most of the glycoproteins synthesized in the perikarion of the hypothalamic secretory neurons migrate inside secretion granules along the axon to the pars nervosa where they are secreted.     

Protein kinase activity of the insulin receptor from muscle

The insulin receptor is associated with a protein kinase activity. This has been shown for the receptor of liver, fat, and some other tissues which are not primary targets of insulin action. Here kinase activity is demonstrated for the insulin receptor of rat skeletal and cardiac muscle with similar characteristics. Insulin (10(-7) mol/l) stimulates phosphorylation of the 95-kDa receptor subunit 3- to 18-fold. The effect is detectable at 10(-10) mol/l insulin; the ED50 is approx. 3 X 10(-9) mol/l. The kinase phosphorylates exogenous substrate as well, and it is recovered after immunoprecipitation of the receptor with antireceptor antibody suggesting that kinase activity is intrinsic to the muscle receptor.     

Lateral interaction of cholesterol in diacylphosphatidylcholesterol bilayers

Thermotropic phase-transition properties of the aqueous dispersions of several diacylphosphatidylcholesterol (DRCh) analogs are examined. The aqueous dispersions of their calcium salts exhibit characteristic endothermic thermotropic transitions due to a change in the conformation of acyl chains. These dispersions consist of osmotically intact liposomes that trap ions, and at the transition temperature there is anomalous increase in the ion leakage. Wide-angle electron diffraction studies of DPCh · Ca monolayers also exhibit a transition from a sharp 4.25 Å band to a broad one centering at 4.7 Å, reflecting an order-disorder transition in the acyl chains. The long-range order in the organization of acyl chains of DRCh molecules could arise from intermolecular interactions between the cholesterol moleties to form a functional dimer, and such dimers are apparently cross-linked by Ca²⁺ to form a long-range interacting lattice of acyl chains. Evidence for this model is adduced from the fluorescence properties of the dispersions of dimyristoylphosphatidylcholesta-5,7,9-trienol. The phase-transition properties of DRCh are an ideal illustration of calcium-induced isothermal phase transition.     

Characteristics of fluorescamine modified bacteriorhodopsin

The light activated proton pump, bacteriorhodopsin was modified with varying amounts of flourescamine, the fluorescamine to protein ratio ranging from 1 to 100. The modified protein was washed free of excess of fluorescamine and reconstituted into phospholipid vesicles to check the proton pumping activity. Although the spectral investigations indicated chemical modification, the circular dichroism measurements pointed to an overall loss of the trimeric structure of the protein. The implications of the present study are that the modifying agent can interact non-specifically with the protein, altering its structural parameters, which in turn affects the function of the protein     

Micropolyspora faeni antigens of three commercial extracts

The protein composition of three commercial extracts of Micropolyspora faeni, produced in U.S.A., England and Italy has been evaluated by agarose gel electrophoresis.By crossed immunoelectrophoresis, tandem-crossed immunoelectrophoresis and by a modification of this last technique, the antigenic composition and the common antigens of the extracts have been investigated. Hyperimmune rabbit serum and a pool of five human sera with precipitins to Micropolyspora faeni have been used as source of antibody.Different quantity and quality of protein content was observed in the available batches. Different antigenic composition was also observed, not directly related to the different proteins contained therein; three antigens were definitely common to all extracts and two of them represented the major antigens of each extract.Despite the total protein content, the major and common antigens were found in similar concentrations in all three products examined. Therefore, the discrepancies observed in the precipitin reactions using the three commercial Micropolyspora faeni extracts are due to differences in the minor antigen composition of the extracts.     

Molecular phylogenetics provides a novel hypothesis of chromosome evolution in Neotropical fishes of the genus Potamorhina (Teleostei,Curimatidae)

Potamorhina includes the largest species in the Neotropical fish family Curimatidae. They perform long-distance migrations in large schools and represent relative importance for regional fisheries in South American lowlands. A morphology-based phylogenetic study recognized five species and proposed interspecific phylogenetic relationships mostly based on osteology, squamation, and morphology of the gasbladder. Subsequent cytogenetic studies revealed extreme variability in diploid numbers and other cytomolecular structures and hypothesized multiple events of chromosome rearrangements with centric fissions followed by reversed fusions. However, neither the taxonomic revision and phylogeny nor the cytogenetic hypothesis of chromosome evolution in Potamorhina was tested using molecular phylogenetic approaches. Here, we use mitochondrial and nuclear DNA sequences to delimit species of Potamorhina with an extensive sampling across the Amazon basin and use phylogenetic methods to test prior hypothesis of multiple events of chromosome rearrangements during the evolution of the genus. Phylogenetic and species delimitation methods clearly support the presence of five species but reveal novel interspecific relationships allowing a reinterpretation of the morphological characters relative to the number of vertebrae, caudal peduncle pigmentation, and modifications in the gasbladder chambers. With the new phylogenetic arrangement, we propose a novel hypothesis of occurrence of a single chromosome fission in the lineage of P. latior followed by an extraordinary event that involved more than 20 chromosome-pair fissions during the evolution of the ancestor of P. altamazonica and P. squamoralevis. This novel hypothesis represents a simpler and more conceivable explanation for the achievement of these elevated chromosome numbers during the evolution of Potamorhina.     

Myocardial expression of transforming growth factor beta family and endothelin-1 in the progression from heart failure to ascites in broilers with cold-induced pulmonary hypertension

We determined mRNA expression of genes of endothelin-1 (ET-1), and of the transforming growth factor beta ligands (TGFβ1, TGFβ2 and TGFβ3), their receptors (TβRI and TβRII) and their pseudoreceptor BAMBI in the heart of broilers raised under cold temperature conditions and affected by pulmonary hypertension. Gene expression was determined by RT-qPCR in right myocardial ventricle samples from 4-week-old chickens (n?=?48) raised either under normal (control) or cold temperature conditions (22?°C versus 14?°C). We do not find differences among healthy birds, birds with cardiac failure and ascitic birds in the mRNA levels of TGFβ2, TGFβ3 and BAMBI. In the control group, ET-1 mRNA level was increased in the ascitic birds as compared with healthy birds and birds with cardiac failure (p?<?0.05) whereas in the cold treated group, no increase was observed (p?>?0.05); yet, ascitic birds in the cold group showed lower mean than ascitic birds in the control group (p?<?0.05). TβRII mRNA expression was higher in ascitic than in healthy birds (p?<?0.05) in both control and cold treated groups; however, in the ascitic birds of the cold treated group TβRII expression was lower than in ascitic birds from the control group (p?<?0.05). Thus, the higher ET-1 and TβRII levels observed in ascitic birds seem to be attenuated by cold.     

Enriching the results of screening social life cycle assessment using content analysis: a case study of sugarcane in Brazil

The International Journal of Life Cycle Assessment - Screening social life cycle assessment (S-LCA) can be applied to identify the social hotspots associated with a production activity or supply...