Biosynthesis of 1-aminocyclopropanecarboxylic acid: Steric course of the reaction at the C-4 position

Summary Under the action of the appropriate synthase from ripe tomatoes a 11 mixture of (3S, 4R)-[3,4-²H₂] and (3R, 4S)-[3,4-²H₂]-(2S)-adenosylmethionine is transformed into a 11 mixture of the two meso forms of [²H₂]-1-aminocyclopropanecarboxylic acid, a result which proves the operation of an inversion mechanism and which is consistent with direct nucleophilic displacement of the leaving group in the substrate.     

Wine technology: Current trends

Conclusion Current enological research does not aim at developing technological wines whose organoleptic characteristics are basically determined by the methods used in the transformation of grape wine, but rather to refine methods which will highlight the original qualities of different cultivars and viticultural conditions.     

Cyclophosphamide-impaired regulation of hepatic heme metabolism

Summary Im male rats hepatic cytochromes b₅ and P-450 were reduced at different times after treatment with cyclophosphamide (CP) (200 mg/kg i.p. for 3 days). In contrast, microsomal heme did not change until 48 h after the last dose of CP, leading to accumulation of heme in a non-cytochromal form. Parallel to the above changes the heme metabolism showed derangement: -aminolaevulinate synthase, the rate-limiting enzyme in heme synthesis, was depressed and heme oxygenase, the enzyme which catalyzes the oxidative degradation of heme, was increased.     

Pineal-related changes in cyclic AMP levels of rat medial basal hypothalamus

Summary Pinealectomy (Px) in adult male rats resulted in increased cyclic AMP accumulation by medial basal hypothalamic (MBH) explants 3 and 7 days after surgery. 24 h after superior cervical ganglionectomy (Gx) an augmented MBH cyclic AMP accumulation was observed. The effects of Px and Gx were additive, as revealed in animals subjected to Gx 3 days after Px.This study was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (N^o 6638) and from the Fundación Alberto J. Roemmers, Argentina.     

‘Chloride-cell’ — like mitochondria-rich cells of salamander larva gill epithelium

Summary Two types of mitochondria-rich cells (MRC) are described ultrastructurally in the gill epithelium of salamander larva. They resemble MRC found in larval ventral epidermis. Histochemical localization of carbonic anhydrase indicated numerous positive reacting cells, most of them flask-shaped. Morphological and functional similarities to fish chloride cells are discussed.     

Ferredoxin reductase catalyzes styrene oxidation to styrene oxide

Summary The flavoprotein ferredoxin reductase catalyzed the oxidation of styrene to styrene oxide in the presence of NADPH. This reaction was inhibited by the addition of catalase and superoxide dismutase. The addition of the nonheme iron protein ferredoxin partially inhibited styrene oxidation. H₂O₂ was also able to catalyze this reaction when added to the enzyme in the absence of NADPH.Acknowledgments. This work was supported by C.N.R. (National Research Council), Rome, Italy contract No. 79.03197.04.     

Juvenile hormone titre and regulation in the cockroachDiploptera punctata

Summary Titres of juvenile hormone (JH) have been determined in both hemolymph and whole body extracts of femaleDiploptera punctata during the first gonotrophic cycle using a method employing gas chromatography/mass spectrometry for qualitative and quantitative analysis. JH III is the sole JH found in both adult and last instarD. punctata. Maximum values of 1500 ng/ml (6M) were observed at the middle of the gonotrophic cycle, when basal oocyte growth rate was greatest. Changes in rates of JH release in vitro by corpora allata paralleled closely the changes in JH titre, suggesting that biosynthesis is a major regulator of titre. JH levels per animal were calculated from observed JH titres, and at certain time points in the gonotrophic cycle JH levels obtained from analysis of whole bodies were significantly greater than those predicted from hemolymph titres. These results suggest the existence of a nonhemolymph JH pool inD. punctata. Decay in JH titre after allatectomy of 5 day females has also been studied. Following a rapid initial decline, the rate of decay slowed appreciably 4 h post-operation. Thus, use of a first-order rate constant to estimate half-life of JH significantly underestimated the longevity of the hormone. The apparent persistence of JH following allatectomy may be due to the existence of a nonhemolymph JH pool.     

Bicuculline and picrotoxin block γ-aminobutryic acid-gated Cl− conductance by different mechanisms

Summary Using isolated, internally perfused bullfrog dorsal root ganglion cells we have studied the dose-response curves for -aminobutyric acid (GABA) in the presence of internally or externally applied GABA antagonists. With external application of antagonists the inhibition of the GABA current by bicuculline was competitive and that by picrotoxin was noncompetitive. Picrotoxin but not bicuculline blocked when internally perfused.To whom reprint requests should be addressed.Acknowledgments. We thank Drs S. Minakami and S. Yasui for helpful discussions and comments.     

Antidiuretic effects of oxytocin in the Brattleboro rat

Summary The antidiuretic activity of oxytocin (OT) was measured in Brattleboro rats with congenital diabetes insipidus. A dose dependent antidiuretic response was found in animals receiving chronic infusions of 0.1 g/h, 1.0 g/h, and 5 g/h of OT. OT infused at the rate of 5 g/h over a 7-day period completely reversed the symptoms of diabetes insipidus. The results support the concept that OT serves as a weak agonist of vasopressin at the level of the kidney and at pharmacological levels exhibits antidiuretic activity.     

Chemical attraction of the eastern yellowjacket,Vespula maculifrons (Hymenoptera: Vespidae)

Summary Workers and queens of the eastern yellowjacket,Vespula maculifrons, are attracted to the artificial long-range attractant pheromone of the predaceous pentatomid,Podisus maculiventris. A 11 mixture of linalool or -terpineol and (E)-2-hexenal is as attractive toV. maculifrons workers as the pheromone.We thank A.S. Menke of the Systematic Entomology Laboratory, USDA, for identifying the yellowjackets. Mention of a company name does not imply endorsement by the US Department of Agriculture.