Bibliographies thématiques / Embryon ascidie

Littérature scientifique sur le sujet « Embryon ascidie »

Auteur : Grafiati
Publié le 25 mai 2024

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Articles de revues sur le sujet "Embryon ascidie"

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Dale, B., L. Santella et E. Tosti. « Gap-junctional permeability in early and cleavage-arrested ascidian embryos ». Development 112, no 1 (1 mai 1991) : 153–60. http://dx.doi.org/10.1242/dev.112.1.153.

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Using the whole-cell voltage clamp technique, we have studied junctional conductance (Gj), and Lucifer Yellow (LY) coupling in 2-cell and 32-cell ascidian embryos. Gj ranges from 17.5 to 35.3 nS in the 2-cell embryo where there is no passage of LY, and from 3.5 to 12.2 nS in the later embryo where LY dye spread is extensive. In both cases, Gj is independent of the transjunctional potential (Vj). Manually apposed 2-cell or 32-cell embryos established a junctional conductance of up to 10 nS within 30 min of contact. Furthermore, since we did not observe any significant number of cytoplasmic bridges at the EM and Gj is sensitive to octanol, it is probable that blastomeres in the 2-cell and 32-cell embryos are in communication by gap junctions. In order to compare Gj in the two stages and to circumvent problems of cell size, movement and spatial location, we used cytochalasin B to arrest cleavage. Gj in cleavage-arrested 2-cell embryos ranged from 25.0 to 38.0 nS and remained constant over a period of 2.5 h. LY injected into a blastomere of these arrested embryos did not spread to the neighbour cell until they attained the developmental age of a 32- to 64-cell control embryo. Our experiments indicate a change in selectivity of gap junctions at the 32-cell stage that is not reflected by a macroscopic change in ionic permeability.
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Yoshida, S., Y. Marikawa et N. Satoh. « Posterior end mark, a novel maternal gene encoding a localized factor in the ascidian embryo ». Development 122, no 7 (1 juillet 1996) : 2005–12. http://dx.doi.org/10.1242/dev.122.7.2005.

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Ascidian embryogenesis is regarded as a typical ‘mosaic’ type. Recent studies have provided convincing evidence that components of the posterior-vegetal cytoplasm of fertilized eggs are responsible for establishment of the anteroposterior axis of the embryo. We report here isolation and characterization of a novel maternal gene, posterior end mark (pem). After fertilization, the pem transcript is concentrated in the posterior-vegetal cytoplasm of the egg and later marks the posterior end of developing ascidian embryos. Despite its conspicuous localization pattern, the predicted PEM protein shows no significant homology to known proteins. Overexpression of this gene by microinjection of synthesized pem mRNA into fertilized eggs results in development of tadpole larvae with deficiency of the anteriormost adhesive organ, dorsal brain and sensory pigment-cells. Lineage tracing analysis revealed that the anterior epidermis and dorsal neuronal cells were translocated posteriorly into the tail region, suggesting that this gene plays a role in establishment of anterior and dorsal patterning of the embryo. The ascidian tadpole is regarded as a prototype of vertebrates, implying a similar function of pem in vertebrate embryogenesis.
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Lambert, C. C. « Ascidian eggs release glycosidase activity which aids in the block against polyspermy ». Development 105, no 2 (1 février 1989) : 415–20. http://dx.doi.org/10.1242/dev.105.2.415.

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To ensure normal development, most animals have evolved a number of mechanisms to block polyspermy including prevention of binding to surface coats as well as sperm-egg fusion. Ascidian sperm bind to vitelline coat (VC) glycosides. In the genus Ascidia, N-acetylglucosamine (GlcNAc) is the ligand to which sperm bind. The number of sperm bound to the VC is biphasic following fertilization; sperm binding increases through the first minute or so, then abruptly declines. At fertilization, the eggs of Ascidia callosa, A. ceratodes, A. mentula, A. nigra and Phallusia mammillata release N-acetylglucosaminidase into the sea water (SW). This has been shown to inactivate VC GlcNAc groups, blocking the binding of supernumerary sperm and polyspermy in A. nigra. This block to polyspermy is inactivated by GlcNAc (2mM) or 150 mM-Na+ (choline substituted) SW. These treatments are not additive and therefore probably affect the same process. In A. callosa, fertilization in low Na+ SW causes a 60% decline in enzyme release and a similar increase in the number of sperm remaining on the VC at 4 min as well as a great increase in polyspermy. Thus the principal block to polyspermy in ascidian eggs involves the release of N-acetylglucosaminidase which appears to be Na+ dependent. Enzyme activity is found in the supernatant SW by 15 s after fertilization, suggesting that it is stored very near the egg surface. Histochemical staining of whole eggs and embryos shows loss of surface-associated enzyme activity following fertilization. Like other lysosomal enzymes this N-acetylglucosaminidase is mannosylated and has an acidic pH optimum.
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Tanaka-Kunishima, Motoko, Kunitaro Takahashi et Fumiyuki Watanabe. « Cell contact induces multiple types of electrical excitability from ascidian two-cell embryos that are cleavage arrested and contain all cell fate determinants ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 293, no 5 (novembre 2007) : R1976—R1996. http://dx.doi.org/10.1152/ajpregu.00835.2006.

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Ascidian early embryonic cells undergo cell differentiation without cell cleavage, thus enabling mixture of cell fate determinants in single cells, which will not be possible in mammalian systems. Either cell in a two-cell embryo (2C cell) has multiple fates and develops into any cell types in a tadpole. To find the condition for controlled induction of a specific cell type, cleavage-arrested cell triplets were prepared in various combinations. They were 2C cells in contact with a pair of anterior neuroectoderm cells from eight-cell embryos (2C-aa triplet), with a pair of presumptive notochordal neural cells (2C-AA triplet), with a pair of presumptive posterior epidermal cells (2C-bb triplet), and with a pair of presumptive muscle cells (2C-BB triplet). The fate of the 2C cell was electrophysiologically identified. When two-cell embryos had been fertilized 3 h later than eight-cell embryos and triplets were formed, the 2C cells became either anterior-neuronal, posterior-neuronal or muscle cells, depending on the cell type of the contacting cell pair. When two-cell embryos had been fertilized earlier than eight-cell embryos, most 2C cells became epidermal. When two- and eight-cell embryos had been simultaneously fertilized, the 2C cells became any one of three cell types described above or the epidermal cell type. Differentiation of the ascidian 2C cell into major cell types was reproducibly induced by selecting the type of contacting cell pair and the developmental time difference between the contacting cell pair and 2C cell. We discuss similarities between cleavage-arrested 2C cells and vertebrate embryonic stem cells and propose the ascidian 2C cell as a simple model for toti-potent stem cells.
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Makabe, Kazuhiro W., Takeshi Kawashima, Shuichi Kawashima, Takuya Minokawa, Asako Adachi, Hiroshi Kawamura, Hisayoshi Ishikawa et al. « Large-scale cDNA analysis of the maternal genetic information in the egg of Halocynthia roretzi for a gene expression catalog of ascidian development ». Development 128, no 13 (1 juillet 2001) : 2555–67. http://dx.doi.org/10.1242/dev.128.13.2555.

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The ascidian egg is a well-known mosaic egg. In order to investigate the molecular nature of the maternal genetic information stored in the egg, we have prepared cDNAs from the mRNAs in the fertilized eggs of the ascidian, Halocynthia roretzi. The cDNAs of the ascidian embryo were sequenced, and the localization of individual mRNA was examined in staged embryos by whole-mount in situ hybridization. The data obtained were stored in the database MAGEST (http://www.genome.ad.jp/magest) and further analyzed. A total of 4240 cDNA clones were found to represent 2221 gene transcripts, including at least 934 different protein-coding sequences. The mRNA population of the egg consisted of a low prevalence, high complexity sequence set. The majority of the clones were of the rare sequence class, and of these, 42% of the clones showed significant matches with known peptides, mainly consisting of proteins with housekeeping functions such as metabolism and cell division. In addition, we found cDNAs encoding components involved in different signal transduction pathways and cDNAs encoding nucleotide-binding proteins. Large-scale analyses of the distribution of the RNA corresponding to each cDNA in the eight-cell, 110-cell and early tailbud embryos were simultaneously carried out. These analyses revealed that a small fraction of the maternal RNAs were localized in the eight-cell embryo, and that 7.9% of the clones were exclusively maternal, while 40.6% of the maternal clones showed expression in the later stages. This study provides global insights about the genes expressed during early development.
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Jeffery, William R., et Billie J. Swalla. « An ankryin-like protein in ascidian eggs and its role in the evolution of direct development ». Zygote 1, no 3 (août 1993) : 197–208. http://dx.doi.org/10.1017/s0967199400001477.

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SummaryAn erythrochyte anti-ankryin antibody was used to investigate the presence and distribution of ankryin in eggs and embryos of ascidian species with different modes of development. In eggs of the indirect developer Ascidia ceratodes anti-ankryin reacted with a 210 kDa polypeptide which has an electrophoretic mobility similar to the vertebrate ankryins. Immunofluorescence microscopy showed that the ankryin-like protein is co-distributed with the myoplasm throughout development. It is restricted to a thin layer under the plasma membrane in unfertilised eggs, undergoes ooplasmic segregation to the posterior pole of the zygote after fertilisation, and is distributed to the tail muscle cells during cleavage and embryogenesis. After gastrulation and neurulation, lower levels of the ankryin-like protein, presumably of zygotic origin, were observed in brain cells and in the apical margin of epidermal cells. The ankryin-like protein was also localised in the myoplasm in eggs and embryos of another indirect developing species, Halocynthia roretzi. The ankryin-like protein may link the cytoskeleton with the plasma membrane in ascidian eggs, as it does in vertebrate erythrocytes. In contrast to A. ceratodes and H. rorefzi, which are members of the families Ascidiidae and Pyuridae respectively, the pattern of ankryin-like protein expression was changed in five species in the family Molgulidae. These molgulid ascidians exhibit either indirect or direct development, and eggs of the direct developing species have lost or modified the myoplasm. The ankryir like protein was present in young oocytes but failed to persist during oogenesis and disappeared in mature eggs and embryos of these molgulid species. The change in ankryin-like protein expression may be a preadaptation for loss of the myoplasm and the evolution of direct development.
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Serras, F., C. Baud, M. Moreau, P. Guerrier et J. A. M. Van den Biggelaar. « Intercellular communication in the early embryo of the ascidian Ciona intestinalis ». Development 102, no 1 (1 janvier 1988) : 55–63. http://dx.doi.org/10.1242/dev.102.1.55.

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We have studied the intercellular communication pathways in early embryos of the ascidian Ciona intestinalis. In two different series of experiments, we injected iontophoretically the dyes Lucifer Yellow and Fluorescein Complexon, and we analysed the spread of fluorescence to the neighbouring cells. We found that before the 32-cell stage no dye spread occurs between nonsister cells, whereas sister cells are dye-coupled, possibly via cytoplasmic bridges. After the 32-cell stage, dye spread occurs throughout the embryo. However, electrophysiological experiments showed that nonsister cells are ionically coupled before the 32-cell stage. We also found that at the 4-cell stage junctional conductance between nonsister cells is voltage dependent, which suggests that conductance is mediated by gap junctions in a way similar to that observed in other embryos.
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Nishikata, T., I. Mita-Miyazawa, T. Deno et N. Satoh. « Muscle cell differentiation in ascidian embryos analysed with a tissue-specific monoclonal antibody ». Development 99, no 2 (1 février 1987) : 163–71. http://dx.doi.org/10.1242/dev.99.2.163.

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Utilizing a muscle-specific monoclonal antibody (Mu-2) as a probe, we analysed developmental mechanisms involved in muscle cell differentiation in ascidian embryos. The antigen recognized by Mu-2 was a single polypeptide with a relative molecular mass of about 220 X 10(3). It first appeared at the early tailbud stage and continued to be expressed until the swimming larva stage. There were distinct and separate puromycin and actinomycin D sensitivity periods during the occurrence of the antigen, suggesting the new synthesis of the polypeptide by developing muscle cells. Embryos that had been permanently arrested with aphidicolin in the early cleavage stages up to the 32-cell stage did not express the antigen. DNA replications may be required for the antigen expression. Embryos that had been arrested with cytochalasin B in the 8-cell and later stages developed the antigen, and the number and position of the arrested blastomeres exhibiting the differentiation marker almost corresponded to those of the B4.1-line muscle lineage. Furthermore, in quarter embryos developed from each blastomere pair isolated from the 8-cell embryo, all the B4.1 as well as a part of b4.2 partial embryos expressed the antigen, while the a4.2 and A4.1 partial embryos did not show the antigen expression. These results may provide further support for the existence of cytoplasmic determinants for muscle cell differentiation in this mosaic egg.
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Wada, S., Y. Katsuyama et H. Saiga. « Anteroposterior patterning of the epidermis by inductive influences from the vegetal hemisphere cells in the ascidian embryo ». Development 126, no 22 (15 novembre 1999) : 4955–63. http://dx.doi.org/10.1242/dev.126.22.4955.

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Patterning along the anteroposterior axis is a critical step during animal embryogenesis. Although mechanisms of anteroposterior patterning in the neural tube have been studied in various chordates, little is known about those of the epidermis. To approach this issue, we investigated patterning mechanisms of the epidermis in the ascidian embryo. First we examined expression of homeobox genes (Hrdll-1, Hroth, HrHox-1 and Hrcad) in the epidermis. Hrdll-1 is expressed in the anterior tip of the epidermis that later forms the adhesive papillae, while Hroth is expressed in the anterior part of the trunk epidermis. HrHox-1 and Hrcad are expressed in middle and posterior parts of the epidermis, respectively. These data suggested that the epidermis of the ascidian embryo is patterned anteroposteriorly. In ascidian embryogenesis, the epidermis is exclusively derived from animal hemisphere cells. To investigate regulation of expression of the four homeobox genes in the epidermis by vegetal hemisphere cells, we next performed hemisphere isolation and cell ablation experiments. We showed that removal of the vegetal cells before the late 16-cell stage results in loss of expression of these homeobox genes in the animal hemisphere cells. Expression of Hrdll-1 and Hroth depends on contact with the anterior-vegetal (the A-line) cells, while expression of HrHox-1 and Hrcad requires contact with the posterior-vegetal (the B-line) cells. We also demonstrated that contact with the vegetal cells until the late 32-cell stage is sufficient for animal cells to express Hrdll-1, Hroth and Hrcad, while longer contact is necessary for HrHox-1 expression. Contact with the A-line cells until the late 32-cell stage is also sufficient for formation of the adhesive papillae. Our data indicate that the epidermis of the ascidian embryo is patterned along the anteroposterior axis by multiple inductive influences from the vegetal hemisphere cells and provide the first insight into mechanisms of epidermis patterning in the chordate embryos.
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Meedel, T. H., R. J. Crowther et J. R. Whittaker. « Determinative properties of muscle lineages in ascidian embryos ». Development 100, no 2 (1 juin 1987) : 245–60. http://dx.doi.org/10.1242/dev.100.2.245.

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Blastomeres removed from early cleavage stage ascidian embryos and reared to ‘maturity’ as partial embryos often elaborate tissue-specific features typical of their constituent cell lineages. We used this property to study recent corrections of the ascidian larval muscle lineage and to compare the ways in which different lineages give rise to muscle. Our evaluation of muscle differentiation was based on histochemical localization and quantitative radiometric measurement of a muscle-specific acetylcholinesterase activity, and the development of myofilaments and myofibrils as observed by electron microscopy. Although the posterior-vegetal blastomeres (B4.1 pair) of the 8-cell embryo have long been believed to be the sole precursors of larval muscle, recent studies using horseradish peroxidase to mark cell lineages have shown that small numbers of muscle cells originate from the anterior-vegetal (A4.1) and posterior-animal (b4.2) blastomeres of this stage. Fully differentiated muscle expression in isolated partial embryos of A4.1-derived cells requires an association with cells from other lineages whereas muscle from B4.1 blastomeres develops autonomously. Clear differences also occurred in the time acetylcholinesterase activity was first detected in partial embryos from these two sources. Isolated b4.2 cells failed to show any muscle development even in combination with anterior-animal cells (a4.2) and are presumably even more dependent on normal cell interactions and associations. Others have noted an additional distinction between the different sources of muscle: muscle cells from non-B4.1 lineages occur exclusively in the distal part of the tail, while the B4.1 descendants contribute those cells in the proximal and middle regions. During the course of ascidian larval evolution tail muscle probably had two origins: the primary lineage (B4.1) whose fate was set rigidly at early cleavage stages and secondarily evolved lineages which arose later by recruitment of cells from other tissues resulting in increased tail length. In contrast to the B4.1 lineage, muscle development in the secondary lineages is controlled less rigidly by processes that depend on cell interactions.
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Thèses sur le sujet "Embryon ascidie"

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Rosfelter, Anne. « Le positionnement du fuseau mitotique chez le zygote d'ascidie et son rôle dans la répartition des organelles ». Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS063.

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Après la fécondation d’un ovocyte, un aster de microtubules se forme autour de l’ADN mâle. Cet aster spermatique permet d’amener le pro-noyau femelle jusqu’au pro-noyau mâle pour qu’ils puissent fusionner. Il permet aussi de déplacer l’ADN fusionné jusqu’au centre de la cellule pour assurer une division cellulaire équitable. Les mécanismes de centration d’un aster ou d’un fuseau ont donné lieu à de nombreuses recherches, que ce soit par modélisation, expérimentalement chez des espèces telles C. elegans, P. lividus, M.musculus ou in vitro sur des extraits de Xenopus laevis. Trois mécanismes principaux se dégagent : le pushing, le cortical pulling et le cytoplasmic pulling (ou bulk pulling). En étudiant le déplacement de l’aster et du fuseau mitotique chez le zygote de l’ascidie P. mammillata j’ai découvert un système qui combine ces trois mécanismes en s’appuyant sur l’alternance des étapes du cycle cellulaire. En méiose, l’aster utilise la polymérisation des microtubules qui le composent pour pousser contre le cortex d’actine et s’en décoller (pushing). Arrivé en interphase, l’aster retourne contre le cortex grâce à une traction qu’exerce la membrane sur les microtubules (cortical pulling). Enfin à l’entrée en mitose, la traction membranaire cesse et libère les asters du fuseau mitotique, qui cèdent donc aux forces exercées par le transport d’organelles vers le centre de l’aster (cytoplasmic pulling) qui semblent constantes durant le cycle cellulaire. Cela permet de centrer le fuseau. En même temps que l’aster se forme et se déplace, une réorganisation des compartiments intracellulaires se met en place. Pour comprendre de quelle manière l’organisation intracellulaire peut être perturbée par la formation de l’aster, j’ai étudié le cas du vitellus. En effet, le vitellus, qui est présent sous forme de vésicules, est initialement abondant et homogène dans l’ovocyte non fécondé. Cependant, dès que l’aster apparaît, sa répartition change et les vésicules de vitellus sont exclues de la zone contenant l’aster. Cette exclusion générée à la formation de l’aster chez le zygote, est maintenue au cours du développement. Dans mes travaux, j’ai pu observer qu’elle est majoritairement due à l’accumulation à l’aster d’autres organelles comme le réticulum endoplasmique. La fonction de transport des microtubules de l’aster suffit donc à réorganiser complètement la cellule en excluant certaines organelles et en en accumulant d’autres. Les déplacements de l’aster et du fuseau mitotique, leur régulation par le cycle cellulaire, et la réorganisation intracellulaire, identifiés ici chez le zygote d’ascidie, s’appuient sur le fonctionnement d’éléments fondamentaux d’une cellule, à savoir : les microtubules, le cortex d’actine, le réticulum endoplasmique, les protéines du cycle cellulaire, etc. Les découvertes présentées revêtent ainsi une portée universelle, adaptable aux spécificités de différents types cellulaires
After oocyte fertilization, a microtubule aster forms around the male DNA. The sperm aster brings the female pro-nucleus to the male pro-nucleus so they can fuse, but it also moves the fused nuclei to the cell center to ensure an equitable cell division. Numerous studies performed in vitro, by modeling or experimentally in species such as C. elegans, P. lividus, and M. musculus, addressed the aster and spindle centration mechanisms. Three main mechanisms emerged; pushing, cortical pulling, and cytoplasmic pulling. By studying aster centration in the zygote of the ascidian P. mammillata, I discovered a system that combines these three mechanisms based on the cell cycle stages. In meiosis, the aster uses the polymerization of its microtubules to push against the actin cortex and move away from it (pushing). Once in interphase, the aster returns to the cortex by a pull exerted by the membrane on the microtubules (cortical pulling). At mitosis entry, cortical pulling stops, and releases the mitotic spindle's asters. In consequence, the asters give in to the forces exerted by the transport of organelles to the aster center (cytoplasmic pulling), that appeared constant during the cell cycle. Cytoplasmic pulling hence participate in centering the spindle While the aster forms and moves, the intracellular compartments reorganize. To understand how intracellular organization can be disrupted by aster formation, I studied the case of yolk. The yolk, in the form of vesicles (called granules or platelets), is initially abundant and homogeneous in the unfertilized oocyte. However, as soon as the aster appears, its distribution changes and the yolk platelets are excluded from the region containing the aster. This exclusion generated by the aster formation in the zygote is maintained during development. I observed that yolk exclusion is mainly due to the accumulation at the aster of other organelles such as the endoplasmic reticulum. The transport function of the aster microtubules is therefore sufficient to completely reorganize the cell by excluding some organelles and accumulating others. The movements of the aster and the spindle, their regulation by cell cycle, and the intracellular reorganization, identified here in the ascidian zygote, rely on basic elements of a cell, namely: the microtubules, the actin cortex, the endoplasmic reticulum, the proteins of the cell cycle, etc. Thus, the discoveries presented here cover a broad scope, and seem adaptable to the specificities of different cell types
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Le, Nguyen Phuong Ngan. « Le déterminant maternel pem-1 et le cortex des oeufs et embryons d’ascidie ». Paris 6, 2012. http://www.theses.fr/2012PA066028.

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Prodon, François. « Polarisation corticale des oeufs et embryons d'ascidie de la maturation à la 1ère division inégale ». Nice, 2004. http://www.theses.fr/2004NICE4097.

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Le cortex des œufs d’ascidies est hautement polarisé suivant l’axe animal-végétatif (a-v) à l’issue de l’ovogenèse, puis suivant les axes Dorso-Ventral (D-V) et Antero-Posterieur (A-P) à partir de la fécondation jusqu’au 1er clivage. Les ovocytes matures d’ascidie sont caractérisés par la distribution en gradient (a-v) de - 1) un domaine sous-cortical riche en mitochondries (appelé myoplasme) ; - 2) d’un domaine riche en Reticulum Endoplasmique cortical (REc) et d’une classe d’ARN messagers corticaux d’origine maternelle (appelée ARNm postplasmiques/PEM). Nous avons montré que la polarisation (a-v) de ces domaines s’effectue au cours de la maturation des ovocytes. Le cortex des œufs subit à l’issue de la fécondation 2 phases majeures de réorganisations. Le myoplasme, le REc ainsi que les ARNm postplasmiques/PEM se concentrent dans le pôle de contraction végétatif (futur pôle Dorsal) au cours d’une première phase majeure de réorganisation acto-myosine dépendante. Le myoplasme, le REc/ARNm corticaux sont ensuite déplacés au niveau du pôle postérieur lors d’une seconde phase majeure de réorganisation dépendante des microtubules. Ces domaines sont répartis de façon équivalente entre les blastomères au cours du premier clivage. Aux stades 2-4 cellules, le myoplasme, le REc et les ARNm postplasmiques/PEM s’accumulent dans les blastomères postérieurs. Au stade 8 cellules, le REc et les ARNm postplasmiques/PEM se concentrent au niveau d’une structure macroscopique corticale appelée CAB (pour Centrosome Attracting Body) localisée dans les blastomères végétatifs les plus postérieurs (B4. 1). Le CAB est impliqué dans la genèse de 3 divisions inégales successives et la ségrégation des ARNm postplasmiques/PEM. Nous avons caractérisé pour la première fois l’évolution et la dynamique de cette polarité corticale en utilisant des cortex isolés à partir d’ovocytes, de zygotes et d’embryons au stade 8 cellules. Nous avons montré que deux ARNm postplasmiques/PEM, PEM1 et macho1, respectivement impliqués dans la formation des axes et la différenciation des cellules musculaires primaires, sont ancrés à la surface d’un réseau polarisé de RE corticale rugueux déjà présent dans les ovocytes matures. Après fécondation, ces ARNm corticaux se concentrent dans le cortex végétatif avec le REc (formant un domaine REc/ ARNm). Ce domaine REc/ARNm se relocalise ensuite en position postérieure avant le 1er clivage et s’accumulent avec celui-ci dans le CAB au stade 8 cellules. Nous discutons 1) le rôle du cytosquelette dans la relocalisation du domaine polarisé riche en REc/ARNm après fécondation, et dans la formation du CAB ; 2) les mécanismes de ségrégation des ARNm postplasmiques/PEM dans les blastomères postérieurs de l’embryon ; 3) les conséquences de ces remaniements dans la différenciation de l’embryon d’ascidie et en particulier celle des cellules musculaires primaires
The ascidian egg cortex is highly polarized along the animal-vegetal (a-v) axis at the end of oogenesis, and along the Dorso-Ventral (D-V) axis and Antero-Posterior (A-P) axis between fertilization and first cleavage. Mature ascidian oocytes display (a-v) gradients of 1) a mitochondria-rich subcortical domain (called myoplasm), 2) a network of cortical Endoplasmic Reticulum (cER), and several cortical maternal mRNAs called postplasmic/PEM RNAs. We show that these domains and mRNAs acquire their polarized distribution during oocyte maturation. After fertilization the oocyte cortex undergoes 2 major phases of reorganization. The cortical (cER) and subcortical (myoplasm) domains are first concentrated in the vegetal contraction pole (future dorsal pole) during an acto-myosin dependant cortical contraction(first major phase of reorganization). The myoplasm, cER/mRNA domains are then translocated posteriorly by a microtubule-dependant movement of the sperm aster with respect to the cortex (second major phase of reorganization). The domains are distributed equally between blastomeres during the first cleavage. At the 2-4 cell stage, the myoplasm, cER and postplasmic/PEM RNAs accumulate in posterior blastomeres. At the 8 cell stage, cER and postplasmic/PEM RNAs are concentrated in a cortical macroscopic structure called Centrosome Attracting Body (CAB) located in the vegetal posterior-most blastomeres (B4. 1). The CAB is involved in the formation of three successive unequal cleavages and in mRNA segregation in small posterior blastomeres. We have characterized for the first time the evolution and dynamics of this cortical polarity using cortex isolation and characterization in oocytes, zygotes and early embryos (8 cell stage). We observe that two postplasmic/PEM RNAs, PEM1 and macho1 respectively involved in axes formation and primary muscle cell formation, are anchored to the surface of the polarized network of cortical rough ER. After fertilization these cortical RNAs are concentrated in the vegetal cortex with the cER (forming a cER/mRNA domain). The cER/mRNA domain moves posteriorly before the first cleavage and compacts into the CAB at the 8 cell stage. We discuss how the cytoskeleton relocates the cER/mRNA domain and how the CAB may form from the translocation and compaction of polarized cER/mRNA domain already present in the oocyte. We also discuss how the segregation of postplasmic/PEM RNAs into specific blastomeres directs development and differentiation of the posterior region of the embryo and particular primary muscle cell formation
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Yu, Deli. « Temporal control of muscle gene expression in an ascidian embryo ». Kyoto University, 2019. http://hdl.handle.net/2433/242897.

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Liu, Boqi. « The gene regulatory network in the anterior neural plate border of ascidian embryos ». Kyoto University, 2020. http://hdl.handle.net/2433/253119.

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Yagi, Kasumi. « Studies on function of Zic family transcription factor genes in early ascidian embryos ». 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147859.

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Sato, Kaoru. « Isolation and characterization of β-catenin downstream genes in early embryos of the ascidian Ciona savignyi ». 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149114.

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Roca, Marianne. « The spindle assembly checkpoint in Phallusia mammillata embryos ». Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS500.

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Le point de contrôle du fuseau mitotique (Spindle Assembly Checkpoint : SAC) retarde l’anaphase jusqu’à ce que tous les chromosomes soient attachés correctement aux microtubules. Le SAC permet ainsi d’éviter des erreurs de ségrégation des chromosomes aboutissant à des cellules filles aneuploïdes (i.e. avec un nombre anormal de chromosomes). L’aneuploïdie, délétère pour les cellules, peut entrainer des problèmes de développement et est observée dans les cancers. Cependant, chez certaines espèces, le SAC n’est pas efficace au cours de la phase précoce du développement embryonnaire. J’ai mis en évidence que chez l’ascidie P. mammillata, un organisme marin du groupe des chordés, le SAC devient efficace au 8ème cycle cellulaire et son efficacité augmente dans les cycles suivants. J’ai démontré qu’en partie ventrale l’identité des cellules antérieures induisait la présence d’un SAC plus efficace mais que d’autres facteurs modulaient aussi l’efficacité du SAC. J’ai étudié les mécanismes moléculaires impliqués dans les variations de l’efficacité du SAC au cours du développement. Mes expériences ont révélé la présence des composants du SAC tout au long de l’embryogenèse. Cependant, j’ai pu montrer que les protéines du SAC ne se localisent pas au niveau des kinétochores lorsque le SAC est inefficace au début du développement mais qu’elles s’y localisent bien dans l’ovocyte en méiose et dans l’embryon plus tardif, lequel se caractérise par un SAC actif. Ma thèse a permis de montrer que P. mammillata est un organisme expérimental de grand intérêt pour l’étude du SAC au cours de l’embryogenèse
During mitosis, progression through anaphase must take place only when all chromosomes are correctly attached to spindle microtubules to avoid chromosome mis-segregation and the generation of aneuploid cells (i.e. with an abnormal chromosome number). Embryos containing aneuploid cells can exhibit developmental defects and lethality. Furthermore, cancer cells are often aneuploid. To prevent such deleterious aneuploidy, a control mechanism, the spindle assembly checkpoint (SAC), delays metaphase-anaphase transition until all chromosomes are properly attached to spindle microtubules. However, the SAC is not efficient during early development in some species. During my thesis, I analyzed the activity of the SAC during the development of the marine chordate P. mammillata. I showed that in P. mammillata embryos, the SAC becomes efficient at the 8th cell cycle and its efficiency increases progressively in the following cell cycles. Although, I demonstrated that patterning of the embryo along the anteroposterior axis influences SAC efficiency, my experiments suggest that additional parameters modulate SAC efficiency. I searched the molecular mechanisms, which control SAC efficiency during development. I collected evidence showing that SAC components are present in oocytes and all post-fertilization stages. I found that SAC proteins localize at kinetochores during meiosis and at later stages when there is an efficient SAC while they do not accumulate on unattached kinetochores in early SAC deficient embryos. My thesis work establishes P. mammillata as a valuable experimental organism to study SAC regulation during embryogenesis
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Scelzo, Marta. « Vasal budding : characterization of a new form of non-embryonic development in the colonial ascidian Polyandrocarpa zorritensis ». Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS467.

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Les tuniciers coloniaux peuvent générer un nouveau corps par reproduction asexuée et par la régénération entière du corps, deux formes de développement non-embryonnaire (DNE). Les différents modes de DNE sont définis en fonction de la nature des tissus organogénétiques. Curieusement, cette capacité est dispersée au sein du sous-phylum, qui contient des espèces capables de DNE (colonial) proches phylogénétiquement d’espèces ou les capacités régénératives sont absentes ou réduites (solitaire). Cela suggère que le DNE a été acquis et perdu plusieurs fois au sein du groupe. L’espèce coloniale Polyandrocarpa zorritensis semble avoir indépendamment acquis la capacité de DNE. Au cours de ma thèse, j’ai caractérisé le DNE dans cette espèce, en identifiant les étapes de DNE en conditions de laboratoire ainsi que les tissus et cellules mises en jeu. J’ai mis en évidence la participation des cellules mesenchymales et de l’épithélium vasculaire dans ce type de DNE. Ça n’a été pas décrit auparavant, et nous avons décidé de l’appeler ‘bourgeonnement vasale’. J’ai observé des cellules mesenchymales non-différenciées se regrouper et proliférer au point de régénération. J’ai décrit les cellules mesenchymales, en identifiant dans les cellules qui prolifèrent un morphotype non-différencié, les hémoblastes, aussi connues comme étant des cellules-souches putatives chez d’autres ascidies coloniales. De plus, j’ai défini la présence d’une étape de quiescence, la sphérule, dans le cycle de vie de P. zorritensis et j’ai caractérisé les variables environnementales et les mécanismes moléculaires mis en jeu dans la quiescence de cette espèce et dans une espèce éloignée, Clavelina lepadiformis
Colonial tunicates can generate a new adult body by asexual reproduction and whole body regeneration, two forms of non-embryonic development (NED). Different modes of NED are defined depending on the nature of the organogenetic tissues. Interestingly, this capacity is scattered across the sub-phylum, with species able of NED (colonial) closely related to species where regenerative capabilities are absent or reduced (solitary). This suggests that NED has been acquired or lost several times among the group. In recent phylogeny of family Styelidae, the colonial species Polyandrocarpa zorritensis seems to have acquired independently the capability of NED. During my PhD, I characterized the NED in this species, identifying the stages of NED under laboratory conditions and the tissues/cells involved. By histological and ultrastructural analyses, I highlighted the participation to NED of vascular epithelium and mesenchymal cells. This type of NED was undescribed before, and we decided to call it “vasal budding”. During the early stages of vasal budding I observed undifferentiated mesenchymal cells cluster and proliferate at the regenerative point; their distribution varies during vasal budding, increasing in the developing areas. I described the mesenchymal cells, identifying in the proliferating cells an undifferentiated morphotype, the hemoblasts, known as putative stem cells in other colonial ascidian. In addition, I defined the presence of a dormant stage, the spherule, in the life cycle of P. zorritensis and I characterized the environmental variable and the molecular mechanisms involved in dormancy in this species and in a distantly related species, Clavelina lepadiformis
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Yamada, Lixy. « Embryonic expression profiles and conserved localization mechanisms of pem-like mRNAs of two species of ascidian, Ciona intestinalis and Ciona savignyi ». 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144235.

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Livres sur le sujet "Embryon ascidie"

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A, Ettensohn Charles, Wray Gregory A et Wessel Gary M, dir. Development of sea urchins, ascidians, and other invertebrate deuterostomes : Experimental approaches. Amsterdam : Elsevier Academic Press, 2004.

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(Editor), Charles E. Ettensohn, Gary M. Wessel (Editor) et Gregory Wray (Editor), dir. Development of Invertebrate Deuterostomes : Experimental Approaches (Methods in Cell Biology) (Methods in Cell Biology). Academic Press, 2003.

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(Editor), Charles E. Ettensohn, Gary M. Wessel (Editor) et Gregory Wray (Editor), dir. Development of Invertebrate Deuterostomes : Experimental Approaches (Methods in Cell Biology) (Methods in Cell Biology). Academic Press, 2003.

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Chapitres de livres sur le sujet "Embryon ascidie"

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McDougall, Alex, Janet Chenevert, Karen W. Lee, Celine Hebras et Remi Dumollard. « Cell Cycle in Ascidian Eggs and Embryos ». Dans Results and Problems in Cell Differentiation, 153–69. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19065-0_8.

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Negishi, Takefumi, et Hiroki Nishida. « Asymmetric and Unequal Cell Divisions in Ascidian Embryos ». Dans Results and Problems in Cell Differentiation, 261–84. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-53150-2_12.

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Jeffery, W. R., B. J. Swalla et J. M. Venuti. « Mechanism of Dorsoventral Axis Determination in the Ascidian Embryo ». Dans Mechanism of Fertilization : Plants to Humans, 591–604. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-83965-8_40.

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Kumano, Gaku. « Early Embryonic Axis Formation in a Simple Chordate Ascidian ». Dans Diversity and Commonality in Animals, 593–614. Tokyo : Springer Japan, 2018. http://dx.doi.org/10.1007/978-4-431-56609-0_28.

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Jeffery, William R. « Ultraviolet-Sensitive Determinants of Gastrulation and Axis Development in the Ascidian Embryo ». Dans Gastrulation, 225–50. Boston, MA : Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-6027-8_14.

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Sawada, Hitoshi, Hiroyuki Kawahara, Yoshiko Saitoh et Hideyoshi Yokosawa. « Physiological Functions of Proteasomes in Ascidian Fertilization and Embryonic Cell Cycle ». Dans Intracellular Protein Catabolism, 229–32. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0335-0_28.

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Matsumoto, Jun, You Katsuyama et Yasushi Okamura. « Multiple cis-Regulatory Regions Control Neuronal Gene Expression of Synaptotagmin in Ascidian Embryos ». Dans The Biology of Ascidians, 158–61. Tokyo : Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-66982-1_26.

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McDougall, Alex, Karen Wing-man Lee et Remi Dumollard. « Microinjection and 4D Fluorescence Imaging in the Eggs and Embryos of the Ascidian Phallusia mammillata ». Dans Methods in Molecular Biology, 175–85. Totowa, NJ : Humana Press, 2014. http://dx.doi.org/10.1007/978-1-62703-974-1_11.

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Wada, Shuichi, et Hidetoshi Saiga. « Cloning and Embryonic Expression of HrzicN, a Zic Family Gene of the Ascidian Halocynthia roretzi ». Dans The Biology of Ascidians, 206–10. Tokyo : Springer Japan, 2001. http://dx.doi.org/10.1007/978-4-431-66982-1_32.

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Paix, Alexandre, Janet Chenevert et Christian Sardet. « Localization and Anchorage of Maternal mRNAs to Cortical Structures of Ascidian Eggs and Embryos Using High Resolution In Situ Hybridization ». Dans Methods in Molecular Biology, 49–70. Totowa, NJ : Humana Press, 2011. http://dx.doi.org/10.1007/978-1-61779-005-8_4.

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Actes de conférences sur le sujet "Embryon ascidie"

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Michelin, Gael, Leo Guignard, Ulla-Maj Fiuza, Patrick Lemaire, Christophe Godine et Gregoire Malandain. « Cell pairings for ascidian embryo registration ». Dans 2015 IEEE 12th International Symposium on Biomedical Imaging (ISBI 2015). IEEE, 2015. http://dx.doi.org/10.1109/isbi.2015.7163872.

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Sardet, C., C. Rouvière, B. Flannery et J. Davoust. « Time lapse confocal microscopy of mitochondrial movements in ascidian embryos ». Dans The living cell in four dimensions. AIP, 1991. http://dx.doi.org/10.1063/1.40578.

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