Relevant bibliographies by topics / Ascidian embryo

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Academic literature on the topic 'Ascidian embryo'

Author: Grafiati
Published: 25 May 2024

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Journal articles on the topic "Ascidian embryo"

1

Cone, Angela C., and Robert W. Zeller. "Using ascidian embryos to study the evolution of developmental gene regulatory networks." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 75–89. http://dx.doi.org/10.1139/z04-165.

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Ascidians are ideally positioned taxonomically at the base of the chordate tree to provide a point of comparison for developmental regulatory mechanisms that operate among protostomes, non-chordate deuterostomes, invertebrate chordates, and vertebrates. In this review, we propose a model for the gene regulatory network that gives rise to the ascidian notochord. The purpose of this model is not to clarify all of the interactions between molecules of this network, but to provide a working schematic of the regulatory architecture that leads to the specification of endoderm and the patterning of mesoderm in ascidian embryos. We describe a series of approaches, both computational and biological, that are currently being used, or are in development, for the study of ascidian embryo gene regulatory networks. It is our belief that the tools now available to ascidian biologists, in combination with a streamlined mode of development and small genome size, will allow for more rapid dissection of developmental gene regulatory networks than in more complex organisms such as vertebrates. It is our hope that the analysis of gene regulatory networks in ascidians can provide a basic template which will allow developmental biologists to superimpose the modifications and novelties that have arisen during deuterostome evolution.
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Wilding, Martin, Marcella Marino, and Daniela Dale. "Nicotinamide alters the calcium release pattern and the degradation of MPF activity after fertilisation in ascidian oocytes." Zygote 7, no. 3 (August 1999): 255–60. http://dx.doi.org/10.1017/s0967199499000647.

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Fertilisation in ascidian oocytes triggers a plasma membrane current, the release of intracellular calcium and the degradation of Maturation Promoting Factor (MPF) activity leading to the completion of meiosis and the initiation of embryo development. We have previously shown that the fertilisation current in ascidians is produced through the metabolism of nicotinamide nucleotide (NN) metabolites to ADP ribose. In this study we have used nicotinamide to test whether NN metabolism plays additional roles in fertilisation in ascidians. Nicotinamide treatment blocked calcium-induced calcium release (CICR) and arrested the cell cycle prior to the completion of meiosis I. Nicotinamide further prevented the abolition of MPF activity after fertilisation. Interestingly, nicotinamide treatment caused ascidian oocytes to form interphase-like pronuclei after fertilisation, despite the high MPF activity. The data demonstrate that NN metabolism is involved in calcium signalling through CICR and further suggest that a NN metabolite acts as a messenger connecting MPF activity to the formation of the meiotic apparatus.
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Yoshida, S., Y. Marikawa, and N. Satoh. "Posterior end mark, a novel maternal gene encoding a localized factor in the ascidian embryo." Development 122, no. 7 (July 1, 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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Bettoni, Rossana, Clare Hudson, Géraldine Williaume, Cathy Sirour, Hitoyoshi Yasuo, Sophie de Buyl, and Geneviève Dupont. "Model of neural induction in the ascidian embryo." PLOS Computational Biology 19, no. 2 (February 3, 2023): e1010335. http://dx.doi.org/10.1371/journal.pcbi.1010335.

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How cell specification can be controlled in a reproducible manner is a fundamental question in developmental biology. In ascidians, a group of invertebrate chordates, geometry plays a key role in achieving this control. Here, we use mathematical modeling to demonstrate that geometry dictates the neural-epidermal cell fate choice in the 32-cell stage ascidian embryo by a two-step process involving first the modulation of ERK signaling and second, the expression of the neural marker gene, Otx. The model describes signal transduction by the ERK pathway that is stimulated by FGF and attenuated by ephrin, and ERK-mediated control of Otx gene expression, which involves both an activator and a repressor of ETS-family transcription factors. Considering the measured area of cell surface contacts with FGF- or ephrin-expressing cells as inputs, the solutions of the model reproduce the experimental observations about ERK activation and Otx expression in the different cells under normal and perturbed conditions. Sensitivity analyses and computations of Hill coefficients allow us to quantify the robustness of the specification mechanism controlled by cell surface area and to identify the respective role played by each signaling input. Simulations also predict in which conditions the dual control of gene expression by an activator and a repressor that are both under the control of ERK can induce a robust ON/OFF control of neural fate induction.
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Mita-Miyazawa, I., T. Nishikata, and N. Satoh. "Cell- and tissue-specific monoclonal antibodies in eggs and embryos of the ascidian Halocynthia roretzi." Development 99, no. 2 (February 1, 1987): 155–62. http://dx.doi.org/10.1242/dev.99.2.155.

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To obtain specific immunological probes for studying molecular mechanisms involved in the early embryonic development of ascidians, we have produced monoclonal antibodies directed against a homogenate of larvae of the ascidian Halocynthia roretzi. Among these, we have screened monoclonal antibodies that specifically recognize cells and/or tissues of the embryo. Characterization of six epidermis-specific monoclonal antibodies (including larval tunic-specific and larval fin-specific), three muscle-specific antibodies, two endoderm-specific antibodies, one notochord-specific antibody and two monoclonal antibodies that specifically recognize trunk-lateral cells suggests that these monoclonal antibodies may be useful as markers for analysing molecular mechanisms involved in specification of these cells. Seven monoclonal antibodies characteristically stain intercellular materials of the developing embryo and may therefore be valid for studying cellular construction of the embryo. Furthermore, monoclonal antibodies that recognize components of follicle cells, perivitelline space and sperm have also been established.
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Munro, Edwin M., and Garrett M. Odell. "Polarized basolateral cell motility underlies invagination and convergent extension of the ascidian notochord." Development 129, no. 1 (January 1, 2002): 13–24. http://dx.doi.org/10.1242/dev.129.1.13.

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We use 3D time-lapse analysis of living embryos and laser scanning confocal reconstructions of fixed, staged, whole-mounted embryos to describe three-dimensional patterns of cell motility, cell shape change, cell rearrangement and tissue deformation that accompany formation of the ascidian notochord. We show that notochord formation involves two simultaneous processes occurring within an initially monolayer epithelial plate: The first is invagination of the notochord plate about the axial midline to form a solid cylindrical rod. The second is mediolaterally directed intercalation of cells within the plane of the epithelial plate, and then later about the circumference of the cylindrical rod, that accompanies its extension along the anterior/posterior (AP) axis. We provide evidence that these shape changes and rearrangements are driven by active extension of interior basolateral notochord cell edges directly across the faces of their adjacent notochord neighbors in a manner analogous to leading edge extension of lamellapodia by motile cells in culture. We show further that local edge extension is polarized with respect to both the AP axis of the embryo and the apicobasal axis of the notochord plate. Our observations suggest a novel view of how active basolateral motility could drive both invagination and convergent extension of a monolayer epithelium. They further reveal deep similarities between modes of notochord morphogenesis exhibited by ascidians and other chordate embryos, suggesting that cellular mechanisms of ascidian notochord formation may operate across the chordate phylum.
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Dale, B., L. Santella, and E. Tosti. "Gap-junctional permeability in early and cleavage-arrested ascidian embryos." Development 112, no. 1 (May 1, 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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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 (July 1, 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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Wada, S., Y. Katsuyama, and H. Saiga. "Anteroposterior patterning of the epidermis by inductive influences from the vegetal hemisphere cells in the ascidian embryo." Development 126, no. 22 (November 15, 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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Tosti, E. "Gap junctional units are functionally expressed before first cleavage in the early ascidian embryo." American Journal of Physiology-Cell Physiology 272, no. 5 (May 1, 1997): C1445—C1449. http://dx.doi.org/10.1152/ajpcell.1997.272.5.c1445.

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Manually apposed ascidian zygotes established electrical communication within 50 min of fertilization and before cytokinesis. Junctional conductance between zygotes was 14.5 +/- 2.9 nS (n = 7), similar to that previously reported for ascidian two-cell-stage blastomeres, suggesting that zygotes and blastomeres express an equivalent number of gap junctional half-channels. Because puromycin at 400 microM does not inhibit the functional expression of these half-channels, they appear to be of maternal origin and their activation does not require protein synthesis. Loading zygotes with 500 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid or exposing zygotes to 10 microM of the calcium ionophore A-23187 shows that these half-channels are regulated by intracellular calcium, consistent with the behavior of these channels in adult tissues. The results show that gap junctional units are expressed in the ascidian at the zygote stage.
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Dissertations / Theses on the topic "Ascidian embryo"

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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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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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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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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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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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Abstract:
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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Books on the topic "Ascidian embryo"

1

A, Ettensohn Charles, Wray Gregory A, and Wessel Gary M, eds. 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), and Gregory Wray (Editor), eds. Development of Sea Urchins, Ascidians, and other Invertebrate Deuterostomes: Experimental Approaches (Methods in Cell Biology, Vol. 74) (Methods in Cell Biology). Academic Press, 2003.

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(Editor), Charles E. Ettensohn, Gary M. Wessel (Editor), and Gregory Wray (Editor), eds. Development of Sea Urchins, Ascidians, and other Invertebrate Deuterostomes: Experimental Approaches (Methods in Cell Biology, Vol. 74) (Methods in Cell Biology). Academic Press, 2003.

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

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Book chapters on the topic "Ascidian embryo"

1

Jeffery, W. R., B. J. Swalla, and J. M. Venuti. "Mechanism of Dorsoventral Axis Determination in the Ascidian Embryo." In 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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Jeffery, William R. "Ultraviolet-Sensitive Determinants of Gastrulation and Axis Development in the Ascidian Embryo." In Gastrulation, 225–50. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-6027-8_14.

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Gandhi, Shashank, Florian Razy-Krajka, Lionel Christiaen, and Alberto Stolfi. "CRISPR Knockouts in Ciona Embryos." In Transgenic Ascidians, 141–52. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7545-2_13.

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Wang, Wei, Claudia Racioppi, Basile Gravez, and Lionel Christiaen. "Purification of Fluorescent Labeled Cells from Dissociated Ciona Embryos." In Transgenic Ascidians, 101–7. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7545-2_9.

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McDougall, Alex, Janet Chenevert, Karen W. Lee, Celine Hebras, and Remi Dumollard. "Cell Cycle in Ascidian Eggs and Embryos." In 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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Lambert, Charles C. "Obtaining Gametes and Embryos of Ascidians." In Methods in Molecular Biology, 27–33. Totowa, NJ: Humana Press, 2014. http://dx.doi.org/10.1007/978-1-62703-974-1_2.

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Negishi, Takefumi, and Hiroki Nishida. "Asymmetric and Unequal Cell Divisions in Ascidian Embryos." In 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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Matsumoto, Jun, You Katsuyama, and Yasushi Okamura. "Multiple cis-Regulatory Regions Control Neuronal Gene Expression of Synaptotagmin in Ascidian Embryos." In 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, and Remi Dumollard. "Microinjection and 4D Fluorescence Imaging in the Eggs and Embryos of the Ascidian Phallusia mammillata." In 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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Paix, Alexandre, Janet Chenevert, and Christian Sardet. "Localization and Anchorage of Maternal mRNAs to Cortical Structures of Ascidian Eggs and Embryos Using High Resolution In Situ Hybridization." In 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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Conference papers on the topic "Ascidian embryo"

1

Michelin, Gael, Leo Guignard, Ulla-Maj Fiuza, Patrick Lemaire, Christophe Godine, and Gregoire Malandain. "Cell pairings for ascidian embryo registration." In 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, and J. Davoust. "Time lapse confocal microscopy of mitochondrial movements in ascidian embryos." In The living cell in four dimensions. AIP, 1991. http://dx.doi.org/10.1063/1.40578.

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