Identification and partial characterization of immunoreactive and bioactive atrial natriuretic peptide from eel heart

Summary Cardiocytes positive for human atrial natriurectic peptide (hANP) were identified histochemically in the eel atrium, but they were not found in the ventricule. Secretory granules were frequently observed in atrial cardiocytes by electron microscopy, but the number of such granules was quite small in the ventricle. Immunogold cytochemistry revealed that immunoreactive ANP (IR-ANP) in atrial cardiocytes was localized in these granules. In spite of poor immunostaining of the eel ventricle, an acid extract of the ventricle contained 25±4 ng·g tissue^-1 (n=9) of IR-ANP when the level of IR-ANP was measured by radioimmunoassay (RIA) for hANP. This level was one eight of that measured in atrial extracts (203±13 ng·g tissue^-1, n=9). Plasma contained 116.7±18.6 pg·ml^-1 (n=9) of IR-ANP. An extract of eel hearts decreased arterial pressure in eels and quail as did hANP. The level of ANP in the extract, as measured by an eel vasodepressor bioassay, was much greater than that measured by RIA for hANP. The immunoreactive and bioactive ANP in the heart extract are identical since the vasodepressor activity disappeared after IR-ANP was absorbed by excess antibodies raised against hANP. Chromatography on Sephadex G-75 generated a major peak of IR-ANP at a position that corresponded to a molecular weight of 14 kD and minor peaks at 3–7 kD from both plasma and heart extract. Reverse phase HPLC of plasma and heart extract generated several peaks of IR-ANP at positions more hydrophilic than those of mammalian ANPs. These results show that eel hearts contain immunoreactive and bioactive ANPs which are distinctly different from hANP. These ANPs are synthesized both in the atrium and in the ventricle, and they are secreted into the circulation mostly in the larger molecular form. The atrial ANP may be stored in the granules and secreted upon exposure of eels to certain stimuli, but the ventricular ANP may be secreted constitutively into the circulation without prior storage in the granules.Abbreviations ANP atrial natriuretic peptide - BSA bovine serum albumin - IR-ANP immunoreactive ANP - PBS phosphate-buffered saline - RIA radioimmunoassay     

Multifunctional hydrolytic catalysis: II. Hydrolysis of p-nitrophenyl acetate by a polymer catalyst which contains hydroxamate and imidazole functions

A water-soluble polymer catalyst was prepared by radical polymerization of a protected hydroxamate monomer, 1-methyl-2-vinylimidazole and acrylamide, and by the subsequent NH₂NH₂ treatment of the polymer. The hydrolysis of p-nitrophenyl acetate by the bifunctional copolymer obeyed typical burst kinetics: rapid accumulation of acetyl hydroxamate group and its slow decomposition. The acetylation rate of the hydroxamate group was rather close to that of a polymer which does not contain the imidazole unit. However, the deacylation was markedly accelerated by the presence of the imidazole unit, and the difference in rate constants amounted to 60- to 80-fold at pH 8–9. These results indicate that the overall catalytic efficiency of the bifunctional polymer is enhanced due to the complementary action of the imidazole and hydroxamate functions.     

Multifunctional hydrolytic catalysis: VI. Catalytic hydrolysis of p-nitrophenyl acetate by N-(4-imidazolylmethyl)benzohydroxamic acid

A bifunctional catalyst, N-(4-imidazolylmethyl)benzohydroxamic acid, was synthesized from benzohydroxamic acid and chloromethylimidazole, and used for the hydrolysis of p-nitrophenyl acetate. The reaction proceeded via the formation of the acetyl hydroxamate and its subsequent decomposition. The deacylation step was shown to be general base-catalyzed by the intramolecular imidazole group on the basis of the deuterium solvent kinetic isotope effect of 2.0. The efficiency of water attack on the acetyl hydroxamate was enhanced 130-fold by the imidazole group. The catalytic process is compared with the reactions of related monofunctional compounds, and finally its significance as a model of the charge relay system is discussed.     

The alpha-glycerophosphate cycle in Drosophila melanogaster. IV. Metabolic, ultrastructural, and adaptive consequences of alphaGpdh-l "null" mutations

"Null" mutations previously isolated at the αGpdh-1 locus of Drosophila melanogaster, because of disruption of the energy-producing α-glycerophosphate cycle, severely restrict the flight ability and relative viability of affected individuals. Two "null" alleles, αGpdh-1^BO-1-4, and αGpdh-1^BO-1-5, when made hemizygous with a deficiency of the αGpdh-1 locus, Df(2L)GdhA, were rendered homozygous by recombination with and selective elimination of the Df(2L)GdhA chromosome. After over 25 generations, a homozygous αGpdh-1^BO-1-4 stock regained the ability to fly despite the continued absence of measurable αGPDH activity. Inter se heterozygotes of three noncomplementing αGpdh-1 "null" alleles and the "adapted" αGpdh-1^BO-1-4 homozygotes were examined for metabolic enzymatic activities related to the energy-producing and pyridine nucleotide-regulating functions of the α-glycerophosphate cycle in Drosophila. The enzyme functions tested included glyceraldehyde-3-phosphate dehydrogenase, cytoplasmic and soluble malate dehydrogenase, lactate dehydrogenase, mitochondrial NADH oxidation, oxidative phosphorylation, and respiratory control with the substrates α-glycerophosphate, succinate, and pyruvate. These activities in any of the mutant genotypes in early adult life were indistinguishable from those in the wild type. There was, however, a premature deterioration and atrophy of the ultrastructural integrity of flight muscle sarcosomes observed by electron microscopy in the "null" mutants. These observations were correlated with a decrease in state 3 mitochondrial oxidation with α-glycerophosphate, succinate, and pyruvate, as well as with loss of respiratory control in adults as early as 2 wk after eclosion. Such observations, which normally are seen in aged dipterans, were accompanied by premature mortality of the mutant heterozygotes. The adapted αGpdh-1^BO-1-4 was identical with wild type in each of the aging characters with the single exception of lowered rates of mitochondrial oxidative phosphorylation.     

Two new iridoid glucosides from Gardenia jasminoides fruits

From the fruits of Gardenia jasminoides which have been employed as Chinese crude drug “Shan-zhii”, two further new iridoid glucosides, gardoside (8,10-dehydrologanic acid) and scandoside methyl ester have been isolated and their structures have been established.     

Activity of synthetic gibberellin A15 and (±)-gibberellin A15isolactone

The activities of (±)-gibberellin A₁₅ ((±)-GA₁₅) and (±)-gibberellin A₁₅-isolactone ((±)-iso-GA₁₅) which were obtained by stereocontrolled total synthesis and gibberellin A₁₅ (E-GA₁₅) synthesized by interconversion of enmein were assayed by the rice seedling test. As expected, (±)-GA₁₅ showed half the activity of natural gibberellin A₁₅ (GA₁₅). E-GA₁₅ which has a natural configuration showed the same activity as natural gibberellin A₁₅ while (±)-iso-GA₁₅ was almost inactive. These samples were also submitted to the cucumber hypocotyl assay. Contrary to what has already been reported, they were almost inactive.     

Synthesis and properties of lunularic acid

Lunularic acid, a natural plant growth inhibitor, has been synthesized. A high concentration (10–30 ppm) effectively inhibited the elongation of root coleoptiles caused by 0·3 and 0·03 ppm indole-3-acetic acid.     

Effect of the pea embryo on formation and degeneration of the mitochondrial membrane in cotyledons during germination

The effect of removal of the embryo on the properties of mitochondriain pea cotyledons was investigated. During imbibition of theseeds, mitochondrial activity was enhanced in the cotyledons.In later stages of germination, respiratory activity of themitochondria decreased gradually, and no response of the mitochondriato exogenous ADP was observed. Moreover, considerable activityof cytochrome oxidase wasrecovered in the post-mitochondrialfraction. Mitochondrial fractions isolated from senescent cotyledonscontained only fragmented particles of mitochondria. On theother hand, in cotyledons excised from the seeds and cultivatedunder wet condition, the initial development of mitochondriademonstrated in the attached cotyledons was suppressed. However,respiratory activity of the mitochondria increased in the laterstages of cultivation. The mitochondria remained unfragmentedand responded to exogenous ADP during all stages of cultivation.Also, a change in the density of mitochondria which occurredin the germinating attached cotyledons was delayed in the cultivatedexcised cotyledons. (Received February 27, 1973; )     

Stepwise synthesis of oligopeptides with N-carboxy α-amino acid anhydrides. II. Oligopeptides with some polar side chains

The reaction of NCA's with some amino acids having a nucleophilic functional group on the side chain was studied in a heterogeneous reaction medium (acetonitrile-water). Glutamic acid and aspartic acid, having a free carboxyl group on the side chain, were successfully used to synthesize oligopeptides without interactions of the γ- and β-carboxyl group with NCA's. Two products were obtained by the reaction of NCA with L -lysine, which contains a free amino group on the side chain. ε-Protected lysine was used to prepare α-peptides as a nucleophile in the reaction. No racemization was observed in the synthesis of peptides by the NCA method in the heterogeneous solvent system. Oligopeptides with some polar side chains were synthesized by the NCA method.     

Degradation of thyroxine by the microsomal particles from rat liver: I. Correlation between thyroxine degradation and lipid peroxides

1.

1. Particles which catalyze the degradation of l-thyroxine labeled with ¹³¹I at the 3′ and 5′ positions in the β-ring have been isolated from rat liver microsomes and purified.