GOLGI APPARATUS, GERL, AND LYSOSOMES OF NEURONS IN RAT DORSAL ROOT GANGLIA, STUDIED BY THICK SECTION AND THIN SECTION CYTOCHEMISTRY

New insights into the ultrastructure and phosphatase localizations of Golgi apparatus and GERL, and into the probable origin of lysosomes in the neurons of fetal dorsal root ganglia and the small neurons of adult ganglia have come from studying thick (0.5–1.0 µ) as well as thin (up to 500 A) sections by conventional electron microscopy. Tilting the thick specimens, by a goniometer stage, has helped to increase our understanding of the three-dimensional aspects of the Golgi apparatus and GERL. One Golgi element, situated at the inner aspect of the Golgi stack, displays thiamine pyrophosphatase and nucleoside diphosphatase activities. This element exhibits regular geometric arrays (hexagons) of interconnected tubules without evidence of a flattened portion (saccule or cisterna). In contrast, GERL shows acid phosphatase activity and possesses small cisternal portions and anastomosing tubules. Lysosomes appear to bud from GERL. Osmium deposits, following prolonged osmication, are found in the outer Golgi element. Serial 0.5-µ and thin sections of thiamine pyrophosphatase-incubated material demonstrate that, in the neurons studied, the Golgi apparatus is a continuous network coursing through the cytoplasm. Serial thick sections of acid phosphatase-incubated tissue suggest that GERL is also a continuous structure throughout the cytoplasm. Tubules of smooth endoplasmic reticulum, possibly part of GERL, extend into the polygonal compartments of the inner Golgi element. The possible physiological significance of a polygonal arrangement of a phosphatase-rich Golgi element in proximity to smooth ER is considered. A tentative diagram of the Golgi stack and associated endoplasmic reticulum in these neurons has been drawn.     

Synthèse d'ARN dans le chondriome au cours de la spermiogenèse chez la Drosophile

Résumé L'incorporation d'uridine-³H dans l'ARN nucléaire et dans l'ARN mitochondrial est détectée à l'aide de l'autoradiographie à haute résolution au cours de la spermiogenèse chez la Drosophile.Le marquage apparaît simultanément sur le noyau et sur le chondriome jusqu'au début de la condensation de la chromatine. Le nebenkern, qui caractérise un des premiers stades de la spermiogenèse, est le territoire cellulaire le plus radioactif. La synthèse de l'ARN nucléaire cesse au cours de la condensation de la chromatine. Pendant ce temps, le marquage des dérivés mitochondriaux se poursuit; il persiste jusqu'à leur complète transformation en paracristal. Ces observations mettent en évidence une synthèse autonome d'ARN par les mitochondries à la fin de la spermiogenèse.

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Autonomous mitochondrial RNA synthesis during spermiogenesis in Drosophila

Summary The incorporation of ³H-uridine into nuclear and mitochondrial RNA has been followed by electron microscope autoradiography during spermiogenesis in Drosophila.Nuclei and mitochondria are simultaneously labeled up to the beginning of the chromatin condensation. The nebenkern, characteristic of the first stages of spermiogenesis, is the most radioactive cellular component. During chromatin condensation, nuclear RNA synthesis ceases, but mitochondrial derivatives continue to be significantly labeled up to their complete paracrystalline transformation. These data show an autonomous RNA synthesis by mitochondria at the end of spermiogenesis.

Ce travail a bénéficié de l'aide du C.N.R.S. (E.R.A. 174), de la D.R.M.E. (contrat 70/414) et du C.E.A. (participation à l'achat de molécules marquées).     

Autoradiographic localization of cholecystokinin binding sites in human cerebellar system using a [I]CCK8 probe

Carboxyl-terminal cholecystokinin octapeptide (CCK8) binding sites were studied in the human cerebellar system by autoradiography. High affinity CCK8 binding sites were demonstrated in the main cerebellar afferent nuclei, namely the inferior olivary complex and the pontine nuclei. This localization of CCK8 binding sites was partly correlated with already described CCK containing terminals. In the cerebellar cortex, high affinity CCK8 binding sites were detected with a laminar distribution. Levels were higher in the granular layer (mostly in the superficial part) and lower in the white matter and the Purkinje cell layer. The non-specific binding was homogenous and particularly low (9%) in the cerebellar cortex but a non-specific binding was selectively localized in the deep cerebellar nuclei. Those results illustrate the species variability of CCK binding sites in the cerebellum and are briefly discussed in relation with the low level of CCK immunoreactivity in this structure. The presence of CCK8 binding sites in cerebellar afferent nuclei and cortex suggests a role of CCK in human cerebellar physiology and particularly in the modulation of afferent inputs to the cerebellum.     

Nebulin seen in DMD males including one patient with a large DNA deletion encompassing the DMD gene

Summary The presence of nebulin in a muscle specimen from a patient with Duchenne muscular dystrophy (DMD) due to a large deletion precludes the possibility that this protein is the DMD gene product.     

Effects of acetazolamide on aerobic exercise capacity and pulmonary hemodynamics at high altitudes.

Aerobic exercise capacity is decreased at altitude because of combined decreases in arterial oxygenation and in cardiac output. Hypoxic pulmonary vasoconstriction could limit cardiac output in hypoxia. We tested the hypothesis that acetazolamide could improve exercise capacity at altitude by an increased arterial oxygenation and an inhibition of hypoxic pulmonary vasoconstriction. Resting and exercise pulmonary artery pressure (Ppa) and flow (Q) (Doppler echocardiography) and exercise capacity (cardiopulmonary exercise test) were determined at sea level, 10 days after arrival on the Bolivian altiplano, at Huayna Potosi (4,700 m), and again after the intake of 250 mg acetazolamide vs. a placebo three times a day for 24 h. Acetazolamide and placebo were administered double-blind and in a random sequence. Altitude shifted Ppa/Q plots to higher pressures and decreased maximum O(2) consumption ((.)Vo(2max)). Acetazolamide had no effect on Ppa/Q plots but increased arterial O(2) saturation at rest from 84 +/- 5 to 90 +/- 3% (P < 0.05) and at exercise from 79 +/- 6 to 83 +/- 4% (P < 0.05), and O(2) consumption at the anaerobic threshold (V-slope method) from 21 +/- 5 to 25 +/- 5 ml.min(-1).kg(-1) (P < 0.01). However, acetazolamide did not affect (.)Vo(2max) (from 31 +/- 6 to 29 +/- 7 ml.kg(-1).min(-1)), and the maximum respiratory exchange ratio decreased from 1.2 +/- 0.06 to 1.05 +/- 0.03 (P < 0.001). We conclude that acetazolamide does not affect maximum exercise capacity or pulmonary hemodynamics at high altitudes. Associated changes in the respiratory exchange ratio may be due to altered CO(2) production kinetics.     

Characterization of a binding site for chemically synthesized lipo-oligosaccharidic NodRm factors in particulate fractions prepared from roots

This paper describes the characteristics of a binding site for the major, lipo-oligosaccharide Nod factor of Rhizobium meliloti in roots of the symbiotic host plant, Medicago truncatula. Chemically synthesized NodRm-IV(Ac, S, C16:2) was labelled by tritiation to a specific activity of 56 Ci mmol^?1 and this ligand was shown to be biologically active in the root hair deformation assay at 10^?11 M. Binding of the ligand to a particulate fraction from roots of M. truncatula was found to be saturable and reversible with an affinity (K_d) of 86 nM and the binding characteristics were consistent with a single class of binding sites. Competition with modified Nod factors showed that the binding was independent of both the O-acetyl and the sulphyl group and did not depend on the unsaturation of the fatty acid. However, both moieties of the lipo-oligosaccharide are required for high-affinity binding since tetra-N-acetyl-chitotetraose and palmitate were found to be poor competitors of ligand binding. A binding site with analogous characteristics was also found in a similarly prepared particulate fraction of tomato roots. This binding site for Nod factors, termed NFBS1, which is present in both a leguminous and a non-leguminous plant, may have a more general role than symbiosis.     

Stratigraphie mineralogique du Pleistocene glacio-torrentiel de la Haute-Durance provencale. Correlations avec le Pleistocene glaciaire du bassin de Laragne-Sisteron

In the Durance valley below Sisteron, the clay minerals of the material forming the fluvio-glacial pleistocene terraces and the superposed paleosols concur to correlate these levels with the glacial complex of the Laragne-Sisteron basin.     

A new species of Asterogyne (Palmae) from French Guiana

Asterogyne guianensis, a new species from French Guiana, is described and illustrated. The differences between this and the morphologically similarA. spicata are given. A map and discussion of distribution is given for all five species of the genus. Studies on the Flora of the Guianas number 28.     

A quantitative structure-activity approach to chemoreception: Importance of lipophilic properties

A multiparameter regression analysis utilizing physico-chemical parameters, and commonly known as the Hansch approach has been extended to a set of existing data on olfactive threshold and olfactive stimulatory effectiveness of organic molecules.The compatibility of various parameters has been studied with adequate statistical methods, and we conclude that the lipophilic character (expressed by the octanol/water partition coefficient) of the molecules is an essential parameter related to preliminary non-specific action and transport across the muceous/lipid interphase and the membrane of the olfactive organ.Such an approach allows the refocusing of the problem of the relationship between structure and olfactive properties.