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31.
32.
Dr. Michel Jangoux Philippe Dubois Anne Lambert Catherine Yourassowsky 《Cell and tissue research》1985,242(3):657-660
Summary A microcanalicular network is demonstrated within the ossicle stroma and the dermal tissue of two asteroid species. Microcanaliculi are presumed to be mesodermal structures. They consist of convoluted tubular ducts lined by epithelial cells associated with scattered basiepithelial nervous processes. Such a microcanalicular system has not been reported previously from any echinoderm species. Its discovery in asteroids entails some conceptual changes, especially considering the physiology of the body wall.Research assistants of the National Fund for Scientific Research (NFSR, Belgium) 相似文献
33.
34.
Stimulation of de novo synthesis of δ-aminolevulinate dehydralasc of radishes grown under far-red light .
Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish ( Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes. 相似文献
Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish ( Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes. 相似文献
35.
Hung Cao Danh Margherita Strolin Benedetti Philippe Dostert 《Journal of neurochemistry》1983,41(3):618-622
Abstract: Aldehyde dehydrogenase (ALDH) activity was measured in brains, livers, and hearts of 23–26-month-old and 3-month-old rats. A significant increase of ALDH activity was found in whole brain of old rats with both acetaldehyde (39%) and propionylaldehyde (15%) used as substrates. In different brain areas of old rats, with acetaldehyde used as substrate, a significant increase of ALDH activity was found in striatum (30–50%) and cerebral cortex (37%). However, no significant difference in ALDH activity was found in livers and hearts of young and old rats. Preliminary experiments showed a significant increase of aldehyde reductase activity (52%) with p -nitrobenzaldehyde used as substrate in whole brain of old rats compared with young rats. The present work indicates that an increase of ALDH activity in brain of old rats may be an adaptive phenomenon. 相似文献
36.
A cDNA clone containing the entire coding sequence of a mouse H-2Kd histocompatibility antigen 总被引:14,自引:4,他引:10 下载免费PDF全文
Jean-Louis Lalanne Christiane Delarbre Gabriel Gachelin Philippe Kourilsky 《Nucleic acids research》1983,11(5):1567-1577
We have isolated a cDNA clone carrying a 1560 bp long insert which contains the entire coding and 3' untranslated regions of an H-2K(d) mouse histocompatibility antigen. Its sequence and overal features are described. They point to the existence of unique properties of DNA sequences associated with the H-2K(d) antigen. 相似文献
37.
Philippe Matile 《Planta》1968,79(3):181-196
Summary Nine acid hydrolases are present in lysosomes which are found in the mitochondrial fraction of a cell-free extract prepared from root tips of corn seedlings.Light and heavy lysosomes can be distinguished. The latter are sedimentable in a sucrose-medium, the former only in sorbitol-medium. The fraction of heavy lysosomes is in turn composed of at least three populations of lysosomes differing in density and enzyme content.Light lysosomes are membrane-bound particles with diameters from 0.3 to 1.5 . Electron micrographs of frozen-etched tissue and isolated particles provide evidence that light lysosomes are identical with small vacuoles. This type of lysosome is characterized by presence of transaminases in addition to that of hydrolases. Heavy lysosomes are small spheres (diameters from 0.1–0.3 ) with membranes resembling those of vacuoles and of the endoplasmic reticulum. These lysosomes are characterized by high specific activities of two oxydoreductases known to occur also in the membranes of the reticulum.The different types of particles are thought to represent stages of the development of the lysosomal apparatus; according to this hypothesis the large vacuole of parenchymatous cells represents the end product of this process. 相似文献
38.
Philippe Boyer 《Insectes Sociaux》1968,15(4):395-405
Summary
Anacanthotermes ochraceus (Burgmeister), in the oasis of Béni-Abbès (Sahara) will establish its colonies only in the low eathern garden walls and in the clay and straw walls of the houses, where it can find both the water and the malleable clayed materials it requires.Soil analyses have given information on the physico-chemical characteristics of some of the termitaria and of the surrounding sand-hill.The organic matter in the termitarium comes both from the soil and the excrement of the termite. It is high in carbon and low in nitrogen (C/N=2,5), and its mineralization in the présense of gravitational water may result in a loss of mobilizable elements such as the bases.Both the Ph and the aeration of the termitarium favour the mineralization of nitrogenous waste material by bacterial agency.The distribution of calcium carbonate and the condition in which it occurs are more important than the total amount present on account of the part it plays in the texture and structure of the materials, of which the termitarium is composed.A statistical granulometric study of the sand fraction with the results expressed as polar coordinates enables, in comparison with those obtained by mechanical analysis, the texture of the materials colonised byAnacanthotermes ochraceus (Burgmeister) to be defined.
Zusammenfassung In der Oase Béni-Abbés (Sahara) gründen dieAnacanthotermes ochraceus (Burgmeister) ihre Kolonien nur in den Wänden der Gärten und in den Mauern der Wohnungen. Dort finden sie das nötige Wasser und die tonigen Plastikmaterialien.Die Bodenanalysen geben Auskunft über einige der characteristichen physikalischchemischen Eigenschaften der Materialien in der Termitenbauten und in dem benachbartem Erg.Das organische Material in den Termitenbauten stammt einerseits aus dem Boden und andererseits aus den Ausscheidungen der Termiten. Reich an Kohlenstoff und arm an Stickstoff (C/N=2,5) kann seine Mineralisation, in Gegenwart von gravifischem Wasser, einen Verlust von einsatzfähigen Elementen, wie den Laugen, nach sich ziehen.Die Bedingungen des Ph und der Belüftung der Termitenbauten sind günstig für eine Mineralisation der stikstoffhaltigen Abfallstoffe auf bakteriellem Wege.Die Verteilung und die Beschaffenheit des CO3Ca sind dort wichtiger als ihre Gesamtauswertung. Der Grund dafür ist die Rolle, die sie auf der Ebene der Textur und des Aufbaus der Materialen in den Termitenbauten spielen.Die Untersuchung der sandigen Bruchstücke durch die granulometrischen Statistiken in Polarkoordinaten, verglichen mit den Ergebnissen der granulometrischen Analyse, erlauben eine Erklärung der Textur der mit Beschlag belegten kolonisierten Materialen durch dieAnacanthotermes ochraceus (Burgmeister).相似文献
39.
Pharmacological Characterization of Somatostatin Receptors in the Rat Cerebellum During Development 总被引:5,自引:2,他引:3
Bruno J. Gonzalez Philippe Leroux Corinne Bodenant Pierre Braquet Hubert Vaudry 《Journal of neurochemistry》1990,55(3):729-737
Abstract: Somatostatin (SRIF) receptors (SRIF-Rs) are transiently expressed in a germinative lamina of the rat cerebellum, the external granule cell layer. The appearance of SRIF-Rs coincides with the expression of SRIF-like immunoreactivity in the cerebellum. However, the cellular location of SRIF-Rs does not overlap with the distribution of SRIF-like immunoreactivity, with the latter being restricted to ascending fibers arising from the brainstem, to perikarya within the white matter, and to some Purkinje cells. The characterization of SRIF-Rs in the immature (13–day-old) rat cerebellum was conducted by means of binding experiments in membraneenriched preparations and autoradiography, using two radioligands, [125I-Tyr0,D-Trp8]SRIF-14 ([125I-Tyr0,d -Trp8]S14) and I25I-SMS 204–090. The pharmacological profile of cerebellar SRIF-Rs was compared with that of adult cortical SRIF-Rs. Saturation studies performed in 13–day-old rat cerebellum showed that the A'D values for [125I-Tyr0,D-Trp8]S14 and 125I-SMS 204–090 binding were 0.35 ± 0.04 and 0.39 ± 0.01 nM, respectively. The corresponding Bmax values were 52.7 ± 4.8 and 49.9 ± 5.3 fmol/mg of protein, a result indicating that radioligands with high specific radioactivity (2,000 Ci/mmol) bind to a single class of high-affinity sites (SSI). Competition studies showed that different D-Trp-sub-stituted analogs displaced [125I-Tyr0,d -Trp8]S14 binding with Hill coefficients >1, a finding indicating the existence of different subtypes of binding sites. When [Tyr0,d -Trp8]S14 was used as a competitor, two sites were resolved by Scatchard analysis in both 13–day-old cerebellum and adult cerebral cortex. The higher-affinity sites correspond to the SSI subtype identified in saturation experiments, whereas the lower-affinity sites most likely correspond to the SS2 subtype. Ionic supplementation studies showed that divalent cations were required to obtain maximal specific binding on the SSI sites. In particular, Mn2+ was the most efficient cation for promoting binding of [125I-Tyr0,d -Trp8]S14. Addition of GTP to the incubation buffer induced a marked reduction of specific binding. The results obtained by membrane binding assays were similar to those obtained by quantitative autoradiography, a result indicating that the microenvironment of SRIF-Rs was preserved in both types of tissue preparations. Receptors expressed in the developing rat cerebellum exhibited the same KD and similar pharmacological profile as those observed in the adult rat cortex. These results show that SRIF-binding sites transiently expressed in the external granule cell layer of the cerebellum of young rats are indistinguishable from adult rat brain SRIF-Rs. The extremely high density of SRIF-Rs found in the external granule cell layer in 13–day-old rats suggests that SRIF may play a pivotal role in the proliferation and/or differentiation of these germinative cells. 相似文献
40.
Morphological and metabolic characterization of a new species of strictly anaerobic rumen fungus: Neocallimastix joyonii 总被引:2,自引:0,他引:2
André Breton Annick Bernalier Frédérique Bonnemoy Gérard Fonty Brigitte Gaillard Philippe Gouet 《FEMS microbiology letters》1989,58(2-3):309-314
A new strain of strictly anaerobic fungi was isolated from the rumen of sheep. This strain is characterized by a polycentric thallus, an extensive and polynuclear rhizomycelium, polyflagellated zoospores with gamma particle-like bodies. We propose to assign this strain in a new species: Neocallimastix joyonii. 相似文献