Christian Cibert

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A key role in the regulation of membrane traffic is played by the rab proteins, members of a family of ras-related small GTP-binding proteins. This family comprises at least 25 identified members, the intracellular localization of only a few of which has been investigated. rab6p has been shown to be distributed along the exocytic pathway in association with(More)
 The development of pectin structural features during the differentiation of cambial derivatives was investigated in aspen (Populus tremula L. × P. tremuloides Michx.) using biochemical and immunocytochemical methods. Comparisons were also made between active and resting tissues. Active tissues, in particular cambial cells and phloem derivatives, were(More)
Sea bass spermatozoa are maintained immotile in the seminal fluid, but initiate swimming for 45 s at 20 degrees C, immediately after dispersion in a hyperosmotic medium (1100 mOsm kg-1). The duration of this motile period could be extended by a reduction of the amplitude of the hyperosmotic shock. Five seconds after the initiation of motility, 94.4 +/- 1.8%(More)
Fertilization increases both cytosolic Ca(2+) concentration and oxygen consumption in the egg but the relationship between these two phenomena remains largely obscure. We have measured mitochondrial oxygen consumption and the mitochondrial NADH concentration on single ascidian eggs and found that they increase in phase with each series of meiotic Ca(2+)(More)
BACKGROUND It is generally assumed that the migration of anterior visceral endoderm (AVE) cells from a distal to a proximal position at embryonic day (E)5.5 breaks the radial symmetry of the mouse embryo, marks anterior, and conditions the formation of the primitive streak on the opposite side at E6.5. Transverse sections of a gastrulating mouse embryo fit(More)
Live trout spermatozoa initiate flagellar motility for a short period of time (30 s at 18 degrees C), during which their mean beat frequency (BF) decreases steadily from 60 to 20 Hz; motility then stops abruptly. When demembranated, the motility of axonemes lasts much longer, up to 20 min, with high beat frequency, provided that ATP (millimolar(More)
In order to isolate new mutations impairing transcriptional regulation of sulfur metabolism inSaccharomyces cerevisiae, we used a potent genetic screen based on a gene fusion expressing XylE (fromPseudomonas putida) under the control of the promoter region ofMET25. This selection yielded strains mutated in various different genes. We describe in this paper(More)
The cell cycle is regulated by phosphorylation events via a cascade of protein kinases and phosphatases, but many of their substrates remain unknown. To study whether proteins of the metaphase II-arrested mouse oocyte meiotic spindle are substrates for phosphorylation events, we used okadaic acid (OA), a potent phosphatase inhibitor, upon fully mature(More)
To investigate whether a specific isotype of tubulin is involved in flagellar motility, we have developed and screened a panel of monoclonal antibodies (mAb) generated against sea urchin sperm axonemal proteins. Antibodies were selected for their ability to block the motility of permeabilized sperm models. The antitubulin mAb B3 completely inhibited, at low(More)
Mutations of the survival motor neuron gene SMN1 cause the inherited disease spinal muscular atrophy (SMA). The ubiquitous SMN protein facilitates the biogenesis of spliceosomal small nuclear ribonucleoproteins (snRNPs). The protein is detected in the cytoplasm, nucleoplasm and enriched with snRNPs in nuclear Cajal bodies. It is structurally divided into at(More)