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排序方式: 共有292条查询结果,搜索用时 15 毫秒
1.
C Batini J M Billard 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1984,299(12):521-524
The spontaneous discharge frequency of Purkinje cells and neurones of the cerebellar nuclei was evaluated in rats after complete bilateral destruction of their inferior olive with 3-acetylpyridine, performed one day to six months before. The deafferentation from the climbing fibers produced an increased inhibitory action of the Purkinje cells on their target neurones, lasting at least for one week. A relative compensation took place progressively during the first month, but the normal activity of the circuit did not recover even after six months. 相似文献
2.
A stereotaxic apparatus and technique for its implantation in diencephalic nuclei of Atlantic salmon parr of 20 to 30 g body weight is described. An atlas of nuclei in the diencephalon is also presented. 相似文献
3.
Structure and activity of proteins from pathogenic fungi Phytophthora eliciting necrosis and acquired resistance in tobacco 总被引:35,自引:0,他引:35
P Ricci P Bonnet J C Huet M Sallantin F Beauvais-Cante M Bruneteau V Billard G Michel J C Pernollet 《European journal of biochemistry》1989,183(3):555-563
The phytopathogenic fungi Phytophthora cryptogea and Phytophthora capsici cause systemic leaf necrosis on their non-host tobacco; in culture they release proteins, called cryptogein and capsicein, which elicit similar necrosis. In addition, both proteins protect tobacco against invasion by the pathogen Phytophthora nicotianac, the agent of the tobacco black shank, that is unable to produce such an elicitor. Cryptogein causes visible leaf necrosis starting at about 1 microgram/plant, whereas 50-fold as much capsicein is required for the same reaction. Capsicein induces protection even in near absence of leaf necrosis. The activities of both elicitors are eliminated upon pronase digestion. They are proteins of similar Mr (respectively 10,323 and 10,155) and their complete amino acid sequences were determined. They consist of 98 residues, with some internal repetitions of hexapeptides and heptapeptides. 85% identity was observed between both sequences: only two short terminal regions are heterologous, while the central core is entirely conserved. Secondary structure predictions, hydropathy and flexibility profiles differ only around position 15 and at the C-terminus; these modifications could play a role in the modulation of their biological activities. After a search of the sequence data bases, they appear to be novel proteins. 相似文献
4.
Spermiogenesis in the rainbow trout (Salmo gairdneri) 总被引:2,自引:0,他引:2
Dr. Roland Billard 《Cell and tissue research》1983,233(2):265-284
In an ultrastructural study on the spermiogenesis of the rainbow trout (Salmo gairdneri R.) four spermatogenetic stages were identified. In young round spermatids, the nuclear chromatin was first heterogeneous (euchromatin and heterochromatin). Subsequently, it became more homogeneous and started to condense in the form of coarse granules and fibers and then into fibrils associated in ribbon-like elements which eventually partly fused together. During early spermiogenesis, a juxtanuclear vacuole appeared in the area where the nuclear envelope was specialized due to condensation of material between the two envelopes and a slight accumulation of nuclear material. This area was finally located in the anterior part of spermatids and spermatozoa; it probably plays a role during fertilization. A flagellar rootlet appeared early in spermiogenesis; it may play a role in the attachment of the flagellum to the nucleus since it persisted until the centriolar complex was definitively fixed in the implantation fossa. The flagellum did not display a plasma membrane and was first located in the cytoplasm, but when it was later extruded from the cell, it acquired a membrane. The cytoplasm was rich in ribosomes (free or in small groups) but poor in membranous organelles. The few mitochondria polarized around the centriolar complex were finally organized into an annular mid-piece. The spermatids remained connected by intercellular bridges until the end of spermiogenesis. The complexity of trout spermiogenesis is intermediate between that in poecilids and that in carp and pike, which have very simple spermatozoa. The role of the material from the nucleus and the cytoplasm reaching the Sertoli cell in the control of spermatogenesis has been discussed. 相似文献
5.
C. Kevers B. Bisbis F. Le Dily J. P. Billard C. Huault Th. Gaspar 《In vitro cellular & developmental biology. Plant》1995,31(2):122-126
The transfer of light-cultured green normal (N) and white habituated (HNO) sugarbeet callus to darkness reduced the growth
of N callus and improved growth and delayed necrosis in the HNO callus. The decrease of dry matter of N callus under darkness
was accompanied by a reduced content of carotenoids and by decreased CO2 fixation, which was compensated by an increased dependency on externally supplied sucrose. The levels of some organic nitrogen
compounds such as glutamate, proline, and free polyamines were not affected by transfer to darkness of N or HNO callus. Darkness
decreased ethylene emissions in both callus types. In the HNO callus, the sucrose growth dependency and the CO2 fixation were unaffected by darkness. Chlorophylls were absent both in light and darkness, whereas some carotenoids were
accumulated in the HNO callus only in dark conditions. In another connection, a significant increase of peroxidase activity,
which did not occur in the N callus, was induced by darkness in the HNO callus. A decreased content of thio-barbituric acid
(TBA)-reactive substances was measured in the HNO callus transferred to darkness, whereas an increase was noticed in the N
callus placed in the same conditions. These metabolic changes and the reduction of cellular damage in darkness revealed light-induced
stress reactions leading to necrosis and to reduced growth of HNO callus. It appeared that darkness allowed the HNO callus
to avoid the photooxidation stress. Therefore, the favorable effect of darkness on HNO growth might be explained by the suppression
of photooxidative damage due to the absence of carotenoids. The higher peroxidase activity in the HNO callus maintained in
darkness raised the problem of heme synthesis in this heterotrophic callus. 相似文献
6.
Disturbed nitrogen metabolism associated with the hyperhydric status of fully habituated callus of sugarbeet 总被引:2,自引:0,他引:2
Frédérik Le Dily Jean-Pierre Billard Thomas Gaspar Claude Huault 《Physiologia plantarum》1993,88(1):129-134
The content of polyamines and proline was much lower in a normal (N) callus of Beta vulgaris L. than in a fully habituated hyperhydric (H) callus. The H callus also contained more glutamate and had a higher glutamate dehydrogenase activity. The excess of glutamate, in this chlorophyll-deficient callus, was linked to accumulation of proline and polyamines. Experiments with α-difluoromethylornithine (DFMO) and α-difluoromethylarginine (DFMA) showed that both ornithine decarboxylase and arginine decarboxylase participated in the synthesis of polyamines (especially spermidine and putrescine) and removal of ammonia. It is hypothesized that the H callus was subjected to ammonia stress from the start of the culture. Experiments with gabaculine, an inhibitor of ornithine aminotransferase, showed that this enzyme linked proline degradation to polyamine synthesis through the production of ornithine. This disturbed nitrogen metabolism appeared to be characteristic of the fully habituated callus and might explain the low growth of this hyperhydric tissue. 相似文献
7.
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9.
Synchronous triggering of trout sperm is followed by an invariable set sequence of movement parameters whatever the incubation medium. 总被引:2,自引:0,他引:2
The movement of live trout spermatozoa is very brief (25 sec at 20 degrees C) and conditions have been developed to get synchronous initiation of sperm motility which allowed quantification of the major parameters of sperm movement during the motility phase. Recorded flagellar beat frequencies decreased steadily from values of 55 Hz at the beginning to 20 Hz at the end of the motility phase. Sperm forward velocities followed a similar pattern from 250 to 20 microns.sec-1 in the same conditions and the diameters of sperm trajectories were reduced from 370 to 40 microns. Thus none of the characteristics of sperm movement was constant during the motile phase which ended abruptly by a straightening of the flagella. The decrease in flagellar beat frequencies and sperm velocities are much greater than what could be extrapolated from the decrease of intracellular ATP (Christen R. et al: Eur. J. Biochem, 166: 667-671, 1987) or from measurements of ATP-dependence of reactivated sperm velocities (Okuno M. and Morisawa N.: In Biological Functions of Microtubules and Related Structures. New York: Academic Press, pp. 151-162, 1982). Therefore, the cessation of flagellar beating at 25 sec is not directly the result of the low concentration of intracellular ATP. The decrease in the diameters of sperm trajectories which occurred during the first part of the motility phase was correlated with [Ca]i measurements (Cosson M.P. et al, Cell Motil. Cytoskeleton, 14:424-434, 1989). The effect of Ca2+ at the axonemal level does not indicates that Ca2+ influx is previous to flagellar beating but rather suggests a classical Ca2+ regulation of the flagellar assymetry. The short duration of the motility phase and the characteristics of sperm movement were very similar in various conditions (high external K+, low pH media) where increased external Ca2+ or divalent ions were shown to overcome K+ and H+ inhibition of sperm motility, both conditions which have been shown to depolarize the plasma membrane potential (Gatti J.L. et al: J. Cell Physiol., 143:546-554, 1990). The present study of the parameters of sperm movement suggests that once motility is initiated, a defined set of axonemal events will take place whatever the external conditions. 相似文献
10.
Stefanie Wagner Frédéric Lagane Andaine Seguin‐Orlando Mikkel Schubert Thibault Leroy Erwan Guichoux Emilie Chancerel Inger Bech‐Hebelstrup Vincent Bernard Cyrille Billard Yves Billaud Matthias Bolliger Christophe Croutsch Katarina Čufar Frédérique Eynaud Karl Uwe Heussner Joachim Köninger Fabien Langenegger Frédéric Leroy Christine Lima Nicoletta Martinelli Garry Momber André Billamboz Oliver Nelle Antoni Palomo Raquel Piqué Marianne Ramstein Roswitha Schweichel Harald Stäuble Willy Tegel Xavier Terradas Florence Verdin Christophe Plomion Antoine Kremer Ludovic Orlando 《Molecular ecology》2018,27(5):1138-1154
Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high‐throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long‐term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human‐induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro‐evolutionary response of trees to climate change and human forest management. 相似文献