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Cyst hatching in Anostraca accelerated by retinoic acid,amplified by Calcium Ionophore A23187, and inhibited by Calcium-channel blockers 总被引:1,自引:1,他引:0
Cyst hatching, under standardized conditions, of the Anostracan species Thamnocephalus platyurus and Streptocephalus dichotomus was significantly accelerated but not increased by applying the morphogen retinoic acid (RA). Cyst hatching was enhanced but not accelerated by artificially increasing the inflow of Ca2+ to the embryonic cells, using Calcium Ionophore A 23 187. Cyst hatching was accelerated and amplified, to a level in excess of the summed effects of each treatment, by a combined application of RA and ionophore. It was inhibited almost quantitatively by the Calcium-channel blockers Nifedipin and Verapamil. The significance of these findings is discussed. 相似文献
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Jean-Georges Casier 《Geobios》1985,18(6):833-855
More than fifty ostracod species, twenty-two of which are Entomozoacea, have been identified in the upper part of the Teferguenite Formation and in the Marhouma Formation. The zonal sequence established on the Entomozoacea is applicable to the Frasnian and the Famennian of the Algerian Sahara; seven zones are recognized. One new species, Tubulibairdia marhoumaensis nov. sp., is described. 相似文献
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Cloning of the spoT Gene of “Candidatus Phlomobacter fragariae” and Development of a PCR-Restriction Fragment Length Polymorphism Assay for Detection of the Bacterium in Insects 下载免费PDF全文
Xavier Foissac Jean-Luc Danet Leyla Zreik Jeanne Gandar Jean-Georges Nourrisseau Joseph-Marie Bov Monique Garnier 《Applied microbiology》2000,66(8):3474-3480
Marginal chlorosis is a new disease of strawberry in which the uncultured phloem-restricted proteobacterium “Candidatus Phlomobacter fragariae” is involved. In order to identify the insect(s) vector(s) of this bacterium, homopteran insects have been captured. Because a PCR test based on the 16S rRNA gene (rDNA) applied to these insects was unable to discriminate between “P. fragariae” and other insect-associated proteobacteria, isolation of “P. fragariae” genes other than 16S rDNA was undertaken. Using comparative randomly amplified polymorphic DNAs, an amplicon was specifically amplified from “P. fragariae”-infected strawberry plants. It encodes part of a “P. fragariae” open reading frame sharing appreciable homology with the spoT gene from other proteobacteria. A spoT-based PCR test combined with restriction fragment length polymorphisms was developed and was able to distinguish “P. fragariae” from other insect bacteria. None of the many leafhoppers and psyllids captured during several years in and around infected strawberry fields was found to carry “P. fragariae.” Interestingly however, the “P. fragariae” spoT sequence could be easily detected in whiteflies proliferating on “P. fragariae”-infected strawberry plants under confined greenhouse conditions but not on control whiteflies, indicating that these insects can become infected with the bacterium. 相似文献
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The fluorescence probe [1-(4-trimethylammonium]-6-phenyl-1,3,5-hexatriene (TMA-DPH) displays properties relevant for both
monitoring endocytosis kinetics and assessing membrane fluidity by fluorescence-anisotropy measurements (1). Thus, it is, possible with this probe to follow the evolution of membrane fluidity during endocytosis, from the very beginning
of the process, i.e., the formation of endocytic vesicles. In most cases, endocytosis is known to start with clathrin-coated
vesicles. Still, there are more and more arguments in favor of a complementary endocytic pathway without clathrin. In this
article we present membrane-fluidity data for very early endocytosis, which allow an upper limit to be determined for the
contribution of a putative nonclathrin pathway. We show that this limit is markedly higher for bone marrow-derived macrophages
than for mouse fibroblasts of the L929 cell line. 相似文献
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Jean-Georges Rozoy 《L'Anthropologie》2003,107(5):645-687
After the strong climatic shocks which happened over and over again, which made the hands free and which started the biological and cultural development of Hominoids, everything depended on the brains of the species concerned and their ability to correlate and invent, because of the constant pressure of their natural and social environment. We are less interested in describing 15 steps here, than in specifying, for each reference mark in a non-stop process, the level reached by mental ability as much cognizantly as affectingly and the neurological bases, which allowed them to occur. This progression was based on the complexification (through epigenesis) of intracerebral connections at different levels allowing us to have large conscience and language, which are the bases of our freedom (via feelings, re-entries and mental pictures). Consequently, men could progressively have control of natural powers, inert ones first (tools), then moving ones (fire), living (hunting) and social ones (slavery); at last, men could free himself from them and perceive them objectively, dominate them, and conceive them in time and abstraction. Writing, then philosophy, then counting and logic have only recently crowned the progress towards the conquest of abstract and humanism through reversive action. The whole show phyletical gradualism, which is still progressing. 相似文献
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Beyond the 75 animal and human pictures, the 491 Magdalenian engraved plaquettes bear 410 abstract signs, in 14 different types, among which eight were unknown up to now in South-Western France, (more than 130 cases). Some examples of all those signs are shown. Besides there are 213 groups of parallel lines. At “Les Beaux-Sarts”, less than 2 m from the hut described in 2003, another human excavation (maybe a tomb?) delivered a schist plaquette with 94 parallel lines carved on its surface, the lines appear as three groups of 14, 7 (or 8?) and 24 (or 28?) lines and one group of 17 (or 18?) oblique lines, with various secondary lines. Five thousand years before the cerebral center of precise calculation was at the beginning of its formation, this piece, out of the bases of which calculation might be subdivided, cannot be considered as the evidence that they were able to count. The author analyses the affective mental possibilities proved by those elements and puts them apart from the rational progress in the abstraction possibilities of the human brain, which occurred later all through ten thousand years. 相似文献
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Véronique Laroulandie Sandrine Costamagno David Cochard Jean-Baptiste Mallye Cédric Beauval Jean-Christophe Castel Jean-Georges Ferrié Lionel Gourichon William Rendu 《Annales de Paléontologie》2008
In this paper, we try to document butchery practices from the past. We attempt to characterize through experimental data the marks produced when dismembering using overextension of the elbow of Sheep and several bird species. For birds, the experimentation was realized with uncooked carcasses. In many cases, overextension produced break down of the olecranon fossa of the humerus, with medial wrench of the distal part. Moreover, the proximal joints of the radius and ulna are broken. Bony and uncooked forelimb Sheep bones have been dismembered by overextension. Observations were noticed only on the radio-ulnar. The ulnas had a negative wear scar up to the anconeus process. Sometimes, these marks are associated with lateral crushing of the bone. In the second part of the article, we compare our experimental data with archaeological material. Although we found many cases of dismembering by overextension on bird bones, no data were found on small ungulates material. 相似文献
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Anne-Frederique Lenne-Gouverneur Annelise Lobstein Gisele Haan-Archipoff Guy Duportail Robert Anton Jean-Georges Kuhry 《Molecular membrane biology》2013,30(2):157-165
Flavonoids are ubiquitous polyphenolic compounds, found in vascular plants, which are endowed with a large variety of biological effects. Some of these effects have been assumed to result from interactions with the cell plasma membrane. In order to investigate the nature of these interactions a fluorescence study was performed with two flavonoids, currently used in one of the laboratories: apigenin and its homologous dimer amentoflavone. After preliminary assays with DPH in several types of phospholipid liposomes, the effects of these flavonoids on the membrane of mouse L929 fibroblasts were compared, using the non-permeant probe TMA-DPH. Amentoflavone, unlike apigenin, induced a static quenching effect, which denoted an important, but reversible, association of the molecule with the plasma membrane. In addition, amentoflavone treatment induced a dose-dependent increase in TMA-DPH fluorescence anisotropy, which could be interpreted as an increase in membrane lipidic order. For apigenin, the effect was much less important. Moreover, exploiting the capacity of TMA-DPH to label endocytic compartments, it was shown that, after association with the membrane, amentoflavone is not internalized into the cell. Possible correlations of these membrane effects with other biological properties are discussed. 相似文献