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Artigos de revistas sobre o assunto "2 cell-Embryo"
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Evsikov, A. V., W. N. de Vries, A. E. Peaston, E. E. Radford, K. S. Fancher, F. H. Chen, J. A. Blake et al. "Systems biology of the 2-cell mouse embryo". Cytogenetic and Genome Research 105, n.º 2-4 (2004): 240–50. http://dx.doi.org/10.1159/000078195.
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FUNAHASHI, Hiroaki, e Koji NIWA. "Electric fusion of 2-cell rat embryo balastomeres." Japanese journal of animal reproduction 36, n.º 2 (1990): 114–19. http://dx.doi.org/10.1262/jrd1977.36.114.
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Zhang, M., L. Sui, Y. Li, Z. Chen, Y. Zhang, T. Liu, J. Xu, X. Zhang e Y. Zhang. "96 EFFECT OF TWO DIFFERENT EMBRYO TRANSPORTERS ON DEVELOPMENT OF PORCINE PARTHENOGENETIC EMBRYOS". Reproduction, Fertility and Development 26, n.º 1 (2014): 162. http://dx.doi.org/10.1071/rdv26n1ab96.
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In the present study, we investigated two embryo transport methods, including a commercial cell transporter and a self-made, simple embryo transporter, for the pre-implantation development of porcine parthenogenetic embryos. The cleaved embryos were randomly distributed between the two types of embryo transport methods and were conserved in vitro for 2, 3, and 4 h. Embryo development efficiency testing and blastocyst differential staining were utilized to assess embryo developmental quality. There were no significant differences in embryo early development efficiency between the commercial cell transporter group, self-made embryo transporter group, and control group. The blastocyst hatch rate (7.75 ± 2.96%) in the self-made simple embryo transport method maintained for 3 h was significantly higher compared to the other groups (P < 0.05). The results (Table 1) showed that blastocyst differential staining showed that the ratio of inner cell mass (ICM) to total cells in both the 2-h-transport group and 3-h-transport group from the self-made simple embryo transport method and the 4-h-transport group from the commercial cell transporter were significantly higher than other groups (P < 0.05).The self-made simple embryo transporter and commercial cell transporter are both effective for transport and conservation of embryos for 3 h. Table 1.Effect of different modes of transport and transit time on embryo development1
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Li, Y., M. L. Day e C. O'Neill. "235.PAF induced changes in intracellular Ca2+ and membrane potential in the 2-cell mouse embryo". Reproduction, Fertility and Development 16, n.º 9 (2004): 235. http://dx.doi.org/10.1071/srb04abs235.
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Platelet-activating factor (PAF) is an autocrine survival factor for the preimplantation embryo. PAF induces a transient increase in intracellular Ca2+ ([Ca2+]i) in 2-cell embryos that is caused by the interdependent influx of external calcium and release of calcium from internal stores. A membrane current with L-type calcium channel properties is activated during PAF-induced calcium signalling. Since the L-type channel in many cell types is primarily voltage-gated we were interested to learn whether this was also the case in the 2-cell embryo. The present study investigated the relationship between the PAF-induced Ca2+ transient and changes in membrane potential (Em) in the 2-cell embryo. The perforated whole-cell patch-clamp technique was used to detect changes in Em and standard calcium imaging techniques were used to measure changes in [Ca2+]i in 2-cell embryos from QS mice. Embryos were first loaded with Fluo-3 and then pretreated with PAF:acetylhydrolase to degrade the embryo derived PAF before patch clamping. Whole-cell perforated patch-clamping was performed by inclusion of 240mg/ml Nystatin in the pipette solution. Changes in Em and [Ca2+]i were recorded simultaneously after treatment of the embryo with PAF. In 2-cell embryos PAF induced a change in Em, consisting of an initial small depolarisation of 2.4 � 0.2 mV (42 � 4 sec after addition of PAF) followed by one or more transient hyperpolarisations of -8 � 1 mV (100 � 9 sec after addition of PAF). Transient increases in [Ca2+]i paralleled the membrane hyperpolaristions and were initiated at 84 � 8 sec after addition of PAF. These responses to PAF were seen in 58% of 2-cell embryos (n = 52). It is not yet clear whether these changes in Em account for the activation of calcium influx through the L-type channel. The results show for the first time that the 2-cell embryo is an electrically active organism.
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Genet, Marion, e Maria-Elena Torres-Padilla. "The molecular and cellular features of 2-cell-like cells: a reference guide". Development 147, n.º 16 (15 de agosto de 2020): dev189688. http://dx.doi.org/10.1242/dev.189688.
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ABSTRACTCurrently, two main cell culture models predominate pluripotent stem cell research: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Thanks to their ability to contribute to and form all tissues within the body, ESCs and iPSCs have proven invaluable in understanding pluripotent states, early embryonic development and cell differentiation, as well as in devising strategies for regenerative medicine. Comparatively little is known about totipotency – a cellular state with greater developmental potential. In mice, only the zygote and the blastomeres of the 2-cell-stage embryo are truly totipotent, as they alone can develop to form the embryo and all of its supportive extra-embryonic tissues. However, the discovery of a rare subpopulation of cells in murine ESC cultures, possessing features of 2-cell embryo blastomeres and expanded cell fate potential, has provided a biochemically tractable model to enable the in vitro study of totipotency. Here, we summarize current known features of these 2-cell-like cells (2CLCs) in an effort to provide a reference for the community, and to clarify what we know about their identity so far.
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Pratt, H. P., e A. L. Muggleton-Harris. "Cycling cytoplasmic factors that promote mitosis in the cultured 2-cell mouse embryo". Development 104, n.º 1 (1 de setembro de 1988): 115–20. http://dx.doi.org/10.1242/dev.104.1.115.
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A cytoplasmic component(s), previously shown to rescue the ‘blocked’ 2-cell mouse embryo in vitro, has been demonstrated to peak in activity during the transition between G2 and M phase and decline thereafter. The possible significance of this component(s) in the regulation of cleavage of the cultured mouse embryo is discussed.
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Sun, Jian Hong, Yong Zhang, Bao Ying Yin, Ji Xia Li, Gen Sheng Liu, Wei Xu e Shuang Tang. "Differential expression of Axin1, Cdc25c and Cdkn2d mRNA in 2-cell stage mouse blastomeres". Zygote 20, n.º 3 (12 de julho de 2011): 305–10. http://dx.doi.org/10.1017/s0967199411000347.
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SummaryThere is increasing evidence to show that 2-cell stage mouse blastomeres have differing developmental properties. Additionally, it has been suggested that such a difference might be due to their distribution of mRNA and/or protein asymmetry. However, to date, the exact genes that are involved in the orientation and order of blastomere division are not known. In this study, some differentially expressed transcripts were identified. Axin1, cell division cycle 25 homolog C (Cdc25c) and cyclin-dependent inhibitor 2D (Cdkn2d) were selected for validation by real-time polymerase chain reaction (PCR) based on published data. Our real-time PCR results demonstrated that Axin1, Cdc25c and Cdkn2d genes had different levels of expression among blastomeres of the mouse 2-cell embryo i.e. the level of Axin1 mRNA was significantly higher in one blastomere when compared with the other blastomeres of the 2-cell embryo (p < 0.05). The variation in Cdc25c (p < 0.05) and Cdkn2d (p < 0.01) mRNA expression followed a similar trend to that of Axin1. In addition, the highest levels of expression of these three genes were detected in the same blastomere in the 2-cell embryo. We confirmed that there was an asymmetrical distribution pattern for Axin1, Cdc25c and Cdkn2d transcripts in 2-cell embryos. In conclusion, this study demonstrated clearly that there is embryonic asymmetry at the 2-cell stage and that these differentially expressed genes may result in differentiation in expression in embryo development.
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Wurlina, Wurlina. "PENGARUH ANTIMITOSIS EKSTRAK Achyranthes Aspera Linn PADA PEMBELAHAN SEL EMBRIO (CLEAVAGE)". Berkala Penelitian Hayati 11, n.º 2 (30 de junho de 2006): 161–65. http://dx.doi.org/10.23869/bphjbr.11.2.200610.
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To study the antimitotic effect of an extract of the leaf Achyranthes asapera Linn on embryonal cleavage rats (Rattus norwegicus). Rats ova were fertilized in vitro, and thes suitable zygote and embryo were selected to use as samples, which were divided into 5 groups. Each group comprised 80 ova/embryo. Those groups were: group 1. ova for fertilization, group 2. zygote, group 3. 2 cell embryo, group 4. 4 cell embryo and group 5. 8 cell embryo. Each group was divided into 4 treatmens, each of which consisted of 20 ova/ embryos. The treatments were as follows: control treatment receiving TCM 199 media, and treatment 1, 2 and 3 receiving Achyranthes aspera Linn alkaloid of 20, 30, and 40 ppm respectively. Observation to embryonal cleavage and development was out 12 and 24 hours after treatment. Concluded from the results that the administration of Achyranthes aspera Linn as much as 30 ppm in vitro could 1) inhibits fertilization zygote and 2, 4, and 8 cell embryonal cleavage, growth and development 2) induced zygote and embryonal membrane recruitment and blastomere degeneration and 3) inhibits zygote and embryonal mitotic cleavage at metaphase stage.
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Forlani, S., C. Bonnerot, S. Capgras e J. F. Nicolas. "Relief of a repressed gene expression state in the mouse 1-cell embryo requires DNA replication". Development 125, n.º 16 (15 de agosto de 1998): 3153–66. http://dx.doi.org/10.1242/dev.125.16.3153.
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In the mouse, transcriptional permissiveness is established in the fertilized egg prior to the activation of zygotic genes at the 2-cell stage. Therefore, gene inactivity initiated at the end of gametogenesis results from a complex process, involving more than an inhibition of the basal transcriptional apparatus. We have examined the ability of the first intron (I1) of the human hypoxanthine phosphoribosyl transferase gene, which functions as an enhancer in embryonic stem cells, to activate a reporter gene when placed proximally to or at a distance from the HSV-tk promoter, or when integrated into the mouse genome as part of a stable transgene. In microinjected embryos, I1 functions as an enhancer sequence; however, its competence for long-range activation appears only after the late 1-cell stage and depends on the first DNA replication. Moreover, activation of microinjected transgenes from proximal enhancers occurs in the late 2-cell embryo and in the male pronucleus of 1-cell embryos blocked for DNA replication; whereas, for integrated transgenes, proximal enhancer activity is subject to position effects in the 2-cell embryo and first occurs at the 2- or 4-cell stage, but only after completion of DNA replication. Therefore, the absence of long-range activation and a non-permissive genomic state (the relief of which both depend on DNA replication), together with an inactive transcriptional apparatus, appear to converge to prevent any gene activity in the 1-cell embryo. We propose that the embryo exploits the process of DNA replication to relieve the transcriptionally repressive state that was initially established to fulfil two purposes: (1) to arrest maternal gene expression in the maturing oocyte and (2) to protect the unicellular egg and 1-cell embryo from premature differentiation. Reactivation of gene expression by DNA replication would therefore serve to coordinate cell proliferation and differentiation in the preimplantation embryo.
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Chen, C. H., T. A. Lin, H. Y. Su, Y. S. Sung, L. J. Sung, S. C. Wu, W. T. K. Cheng et al. "157 AGGREGATION AND DEVELOPMENT OF RABBIT CLONED EMBRYOS WITH ZYGOTIC, TETRAPLOID, AND PARTHENOGENETIC EMBRYO IN VITRO". Reproduction, Fertility and Development 22, n.º 1 (2010): 237. http://dx.doi.org/10.1071/rdv22n1ab157.
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The rabbit compared to other domestic animals, such as cattle and sheep, was a relatively more difficult species to clone. One of the major reasons may be attributed to the low cell number in cloned embryo before implantation. This study was designed to aggregate 2 nuclear transfer (NT) embryos and one with a different origin, determine their developmental potential in vitro, and finally examine the cell number of aggregated embryos. NT was performed with our standard procedure using in vivo derived oocytes and donor cells from adult skin fibroblasts. Zygotes (ZY) were collected from does at 18 h post-hCG and mating. Parthenogenetic (PA) embryos were generated from oocytes with activation protocol, whereas tetraploid embryos (4N) were prepared by fusing fertilized embryos at 2-celled stage into 1-celled stage by electrical pulse. All of the embryos were cultured for 20-24 h into 4-/8-celled stage prior to aggregation. Zona pellucida was then removed and 2 NT embryos were aggregated with 1 embryo originated from ZY, PA, and 4N groups in a depressed droplet containing culture medium. Aggregated embryos were cultured for another 48 h (total 3 days, initiation of activation = Day 0) before being fixed for cell counting. Both single embryo from NT, ZY, PA, and 4N and 3 embryo aggregates (3X) from the same category were used as controls for NT aggregation. The results of 3-day embryo culture in vitro showed that the development of aggregated embryos to blastocyst (BL) stage was 2 NT + ZY, 68.6% (n = 35); 2 NT + 4N, 91.7% (n = 36); and 2 NT+PA, 37.5% (n = 24), whereas 3X aggregates developed to BL at a rate of ZY, 100% (n = 24); 4N, 100% (n = 19); and PA, 100% (n = 14). The BL rates of single embryo control developed into early BL were ZY, 100% (n = 34) and 4N, 93% (n = 36); however, NT and PA developed slower, only 45.4% NT (n = 187) and 79.2% PA (n = 72) to compacted morula/early BL stage. Cell counting data (Table 1) showed that there was no difference in cell number per embryo between NT and PA, whereas ZY and 4N possessed significantly higher cell number than NT and PA (128-162 v. 52-61, P < 0.05) for single embryo category. In the 3X aggregation group, significantly higher cell number per aggregated embryo was found in ZY and 4N compared to that in PA (549-564 v. 196, P < 0.05). More importantly, there was significantly higher cell number found in 2 NT + 4N embryo than that in single 4N (293 v. 162, P < 0.05). This result demonstrated that 2 cloned embryos had propagated and incorporated into 1 tetraploid embryo during pre-implantational development. The next step is to study how NT embryos successfully interact within the aggregated embryo during further development and differentiation, in order to increase the birth rate of clones. Table 1.The cell number of aggragated rabbit embryos between NT and other embryos of different origin after 3 days of culture in vitro Supported by NIH 5R44HL091605-03.
Teses / dissertações sobre o assunto "2 cell-Embryo"
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Patel, M. "The charecterisation of the adenovirus 2-E1 genes that transform normal rat embryo fibroblasts to immortal cell lines". Thesis, University of Essex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381249.
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Patel, M. "The characterisation of the adenovirus 2-E1 genes that transform normal rat embryo fibroblasts to immortal cell lines". Thesis, University of Essex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332650.
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Lu, Fu-i. "Control of cell movements and early patterning of the zebrafish (Danio rerio) embryo by Angiomotin like 2 and Frz". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/LU_Fu-I_2007.pdf.
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J'ai analysé la fonction de deux gènes, Angiomotine like2 (Amotl2) et FrzA et démontré qu'ils jouent un rôle essentiel dans le contrôle de la détermination cellulaire et des mouvements cellulaires au cours de l'embryogenèse du poisson zèbre. Amotl2 est impliqué dans le contrôle des mouvements cellulaires incluant les mouvement d'épibolie et de convergence et extension. Au niveau moléculaire Amotl2 interagit préférentiellement et facilite la translocation membranaire de la forme phosphorylée de c-Src résultant en la régulation de l'architecture de la membrane. J'ai montré que l'expression d'Amotl2 est sous le contrôle de la voie de signalisation FGF et que ce gène est aussi requis pour la sécrétion de Wnt8. FrzA est aussi requis pour le contrôle des mouvements cellulaires et de la mise en place du patron embryonnaire. Ce gène régule négativement l'activité maternelle de la β-caténine. Il semble agir de manière paracrine et être un facteur agissant à courte distance agissant de manière différente de FrzB et DKK1. L'inhibition de la β-caténine maternelle par FrzA est médiée par le récepteur Frizzled 2I analyzed the function of two genes, Angiomotin like 2 (Amotl2) and FrzA (SFRP1, Secreted Frizzled Related Protein 1) and demonstrated that they play an essential role in controlling the cell fates and cell movements during the embryogenesis of the zebrafish (Danio rerio). Amotl2 is involved in the control of embryonic cell movements. I demontrated that Amotl2 interacts preferentially with and facilitates outward translocation of the phosphorylated c-Src, which may in turn regulates the membrane architecture. Amotl2 is under the control of the FGF signaling pathway and this gene is also required for the patterning of the embryo. Preliminary data suggest that Amotl2 is required for the secretion of Wnt8. FrzA is also required for proper cell movements and embryo patterning. Analysis of FrzA function indicates that this gene negatively regulates maternal β-catenin signaling. FrzA appeard to act in a paracrine manner and acts at short range. I established that FrzA acitivity is different from those of FrzB and DKK1. Furthermore, I showed that the inhibition of the maternal β-catenin signaling by FrzA is mediated by the Frizzled 2 receptor
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Cortés, Albarracín Paola Andrea 1990. "Investigating the role of transcription factor Nkx1-2 in mouse embryonic stem cell pluripotency, self-renewal and differentiation". Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668122.
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Mouse embryonic stem cells (ESCs) require extracellular signals to induce the expression of
intrinsic core pluripotency factors: Oct4, Sox2 and Nanog, known as the OSN triad. Notably, the
Wnt/β-catenin pathway has been shown to be important for controlling the expression of
transcription factors that orchestrate the characteristic ESC gene expression programme. It remains
unclear, however, the exact mechanisms by which the Wnt pathway (via tcf3) contributes to
enhance the maintenance of ESCs in a naïve state. Furthermore, little is known of the identity of
Wnt-dependent downstream targets that elegantly regulate this ESC state. To identify these Wnt-
dependent important transcription factors (TFs) or master regulators (MRs), we used a reverse
engineering approach that allowed us to identify several TFs with unknown function in ESCs. The
work in this thesis is focused on investigating the function of Nkx1-2 in controlling naïve
pluripotency, and we propose it as a novel TF as it had never been described before. Here, we
discovered that Nkx1-2 has dual functions in ESC biology. In fact, Nkx1-2 can delay ESC
differentiation upon LIF withdrawal and its deletion leads to abnormal pluripotency-specific
protein expression. Also, Nkx1-2 is important for ESC differentiation and cell-fate specification
in the early mouse embryo development. Overall, this work reveals a novel role for Nkx1-2 in ESC
pluripotency and differentiation.Las células embrionarias de ratón (ESCs), requieren de señales extracelulares para inducir la expresión de factores intrínsecos de pluripotencia: Oct4, Sox2 y Nanog, conocidos como la tríada OSN. Notablemente la vía de señalización Wnt/beta catenina, ha demostrado ser crucial en el control de la expresión génica de factores de transcripción en ESCs. Hasta ahora los mecanismos mediante los cuales, la vía de señalización Wnt (via Tcf3) contribuyen a potencializar el mantenimiento de las ESCs en su estado característico, no han sido esclarecidos. Además, muy poco se sabe sobre la identidad de los genes diana dependientes de Wnt y cómo regulan el estado pluripotente de las ESCs. Para identificar estos factores de transcripción (FT) reguladores dependientes de Wnt, hemos usado una estrategia inversa que nos ha ayudado a identificar FTs, cuya función en las ESCs es desconocida. El trabajo presentado en esta tesis se enfoca en investigar la función del gen no descrito hasta la fecha Nkx1-2, en el control de la pluripotencia de las ESCs. Hemos descubierto que Nkx1-2 tiene funciones duales en las células embrionarias de ratón. De hecho, Nkx1-2 puede retrasar la diferenciación de las células en ausencia de LIF, y su deleción causa una expresión aberrante de los factores importantes en mantener la pluripotencia. Además, Nkx1-2 es importante para la diferenciación apropiada de las células madre y también lo es en la especificación celular durante el desarrollo embrionario. En general, el trabajo en esta tesis revela una nueva función para Nkx1-2 en la pluripotencia y diferenciación de las células madre embrionarias de ratón.
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Shajahan, Shireen. "Z-DNA drives Zscan4-dependent chromatin reorganization to induce and safeguard totipotent stem cell identity". Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS221.pdf.
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Le développement d'un organisme complexe repose sur une séquence de décisions cellulaires conduisant à l'émergence de centaines de types cellulaires différents avec des fonctions spécifiques. Cette progression est marquée par une perte graduelle de la potence cellulaire, des changements significatifs du transcriptome et un remodelage étendu de la chromatine. Les embryons totipotents à 2 cellules (2C) se caractérisent par une signature transcriptionnelle unique et une organisation de la chromatine relâchée (hypométhylation globale, faible compaction de la chromatine, accessibilité accrue de la chromatine). Cependant, comment les embryons 2C préservent leur identité cellulaire stricte dans une conformation de chromatine permissive reste mal compris.La conversion spontanée des cellules souches embryonnaires de souris (mESCs) à un état semblable à celui des embryons 2C, appelé cellules 2C-like (2CLCs), fournit un modèle in vitro idéal pour étudier les caractéristiques de la totipotence, dont elles partagent plusieurs traits avec les embryons 2C. Pour étudier les interactions de la chromatine à l'échelle du génome, des expériences de capture de conformation des chromosomes (Hi-C) ont été menées dans les mESCs et les 2CLCs. Bien que l'architecture globale des chromosomes soit restée globalement stable entre les deux populations cellulaires, nous avons identifié de nouvelles larges régions d'interaction spécifiques aux 2CLCs, principalement situées vers une extrémité de nombreux chromosomes. Des expériences de ADN-FISH ont montré que ces interactions se localisent à la périphérie nucléaire des 2CLCs, associées à un changement de marque d'histone, passant d'actif dans les ESCs à répressif dans les 2CLCs, empêchant l'activation transcriptionnelle dans ces régions. La formation de ces interactions de la chromatine dépend des protéines de la famille Zscan4, un facteur de la chromatine exprimé spécifiquement au stade 2C. De manière intrigante, il a été démontré que Zscan4 se lie à des motifs prédisposés à adopter une conformation en Z-ADN, caractérisée par une double hélice gauche. Nous avons détecté la présence de Z-ADN dans les 2CLCs, et leur induction a significativement augmenté la proportion de 2CLCs affichant des conformations de chromatine similaires à celles des 2CLCs spontanés.En résumé, nous proposons un mécanisme en deux étapes dans lequel la formation de Z-ADN induit l'émergence de 2CLCs, suivie de leurs relocalisations à l'enveloppe nucléaire formant de grands domaines d'interactions dépendants de Zscan4, qui pourraient être cruciaux pour préserver la totipotence dans un environnement de chromatine globalement permissifMammalian development is characterized by a sequence of cell fate decisionsalong an irreversible pathway of restricted developmental potential and increasingcell specialization. With progressing development, a gradual restriction inpotency is accompanied by significant transcriptome modulation and drasticchromatin reprogramming. Totipotent 2-cell (2C) embryos are defined by aunique transcriptional signature and a relaxed chromatin organization (globalhypomethylation, poor chromatin organization and increased chromatinaccessibility). However, how 2C embryos safeguard their strict cell identity in arelaxed chromatin conformation remains poorly understood.The spontaneous conversion of mouse embryonic stem cells (mESCs) to a 2C-like state, called 2C like cells (2CLCs), provides a convenient in vitro modelsystem to study totipotent-like characteristics as they share several features with2C embryos. To investigate genome-wide chromatin interactions, chromosomeconformation capture experiments (Hi-C) were conducted in both mESCs and2CLCs. While the global chromosome architecture remained stable between thetwo cell populations, we identified new large interacting regions specific to2CLCs, located towards one end of numerous chromosomes. The formation ofthese chromatin interactions depends on Zscan4, a transcription factor expressedspecifically at the 2C stage. Intriguingly, Zscan4 binds to motifs predisposed toadopt a Z-DNA conformation, characterized by a left-handed double helix. Wedetected the presence of Z-DNA in 2CLCs, and inducing it significantly increasedthe proportion of 2CLCs displaying chromatin conformation akin to spontaneous2CLCs. Mechanistically, we propose that Z-DNA formation plays a role inaltering DNA replication timing, a process known to promote cell transitions.In summary, we propose a novel role for Zscan4 in forming 3D genomeinteraction, a process that may be critical in establishing and maintainingtotipotency
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Maire, Marie-Aline. "Inhibition de l'apoptose comme facteur de la transformation morphologique des cellules embryonnaires de hamster Syrien". Metz, 2004. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2004/Maire.Marie_Aline.SMZ0434.pdf.
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Le but de ce travail consistait d'une part, à étudier l'hypothèse qu'une défaillance des processus apoptotiques favoriserait la transformation cellulaire, et d'autre part, à élucider certains des mécanismes moléculaires de substances inhibitrices de l'apoptose. Ce travail a été réalisé sur les cellules embryonnaires de hamster Syrien, des cellules normales, diploïdes et capables de métaboliser un grand nombre de substances chimiques. Cette étude a été appliquée à trois substances, le zinc, inhibiteur de l'apoptose, le DEHP (di-2-ethylhexyl phtalate), transformant in vitro, le 2,4-D (acide 2,4-dichlorodiphénoxyacétique), apparenté au DEHP au plan mécanistique, en tant que proliférateur de peroxysomes hépatiques. Dans une 1ère partie, nous avons montré que les substances anti-apoptotiques testées (zinc et DEHP) induisaient la transformation morphologique des cellules SHE. Quant au 2,4-D, il augmentait la transformation morphologique des cellules SHE mais sans inhiber l'apoptose. Dans une 2nde partie, nous avons montré que le zinc et le DEHP exerçaient leurs propriétés anti-apoptotiques en augmentant le ratio des protéines Bcl-2/Bax. Les résultats concernant l'implication du proto-oncogène c-myc dans l'apoptose et dans la transformation cellulaire, sont plus complexes. Le 2,4-D augmente l'expression de c-myc ce qui pourrait être relié à l'augmentation de la transformation morphologique. Quant au DEHP, il diminue l'expression de c-myc parallèlement à l'augmentation de Bcl-2, suggérant que c-myc pourrait interagir avec certains gènes de la voie apoptotique mitochondrialeApoptosis, a cell suicide pathway, is implicated in various physiological events, in particular the elimination of damaged cells. The defective regulation of apoptosis may contribute to the etiology of cancer and the impairment of normal cell death process has been implicated in neoplastic transformation. In order to test the hypothesis of a relationship between apoptosis and neoplastic transformation, we studied three chemicals, zinc as inhibitor of apoptosis, DEHP (di-2-ethylhexyl phtalate) which induced cell transformation and 2,4-D (2,4-dichlorodiphénoxyacetic acid), a peroxysome proliferators such DEHP. First, we demonstrated that anti-apoptotic chemicals (zinc and DEHP) induced SHE cell transformation. These results were in agreement with the theory of a relationship between the inhibition of apoptosis and the induction of cell transformation. However, 2,4-D induced SHE cell transformation while it has no effect on apoptosis. Second, we showed that zinc and DEHP inhibited apoptosis through an increase of the bcl-2/bax ratio. Results concerning the involvement of the proto-oncogene c-myc in apoptosis and in cell transformation are more complex. We showed that 2,4-D induced c-myc expression at concentrations which induced cell transformation. On the opposite, DEHP decreased c-myc expression which could be related to the increase of the Bcl-2 expression
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Ferraz, Gustavo Dantas. "A proteção do direito fundamental à vida e as pesquisas com células-tronco embrionárias humanas no ordenamento jurídico brasileiro". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/2/2134/tde-07022011-154645/.
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A dissertação trata do debate acerca do início da proteção do direito à vida e as consequências dessa proteção em relação às pesquisas com células-tronco embrionárias humanas, autorizadas no ordenamento jurídico brasileiro pelo artigo 5º, da Lei nº 11.105/2005, julgada constitucional pelo Supremo Tribunal Federal em sede de controle concentrado de constitucionalidade. A abordagem, que se concentrou no estudo da doutrina, legislação e jurisprudência, tem caráter preponderantemente dogmático jurídico, nas dimensões analítica, empírica e normativa. As principais conclusões são as seguintes: o direito à vida garantido pela Constituição Federal, estruturalmente, consiste em um princípio, com âmbito de proteção amplo, ensejando a necessidade de sopesamento com outros valores protegidos pelo ordenamento jurídico para sua aplicação; dentre as possíveis interpretações acerca do que consiste esse direito, ele pode ser considerado como um direito à própria existência, um direito à vida digna e um direito à proteção em face do desenvolvimento da biotecnologia; o início da proteção do direito à vida e as pesquisas e terapias com células-tronco embrionárias são disciplinados no direito brasileiro por dispositivos internacionais e nacionais, tais como a Convenção Americana de Direitos Humanos, a Constituição Federal e a Lei nº 11.105/2005; o fato de o Supremo Tribunal Federal ter considerado constitucional o artigo 5º, da Lei nº 11.105/2005, em sede de controle concentrado, não afastou a aplicação da Convenção Americana de Direitos Humanos (a qual contém norma que protege o direito à vida, em geral, desde a concepção) e nem impediu um controle estatal e internacional efetivo sobre as pesquisas e terapias com células-tronco embrionárias a fim de resguardar, dentre outros aspectos, o direito à vida em um enfoque transindividual.The present work deals with the debate about the beginning of the protection of the right to life and the consequences of this protection related to human embryo-based stem cell research, authorized by the Brazilian legal legislation according to the Article 5 of Law no. 11.105/2005, considered constitutional by the Federal Supreme Court in the concentrated model of constitutional control. The approach, centralized in the study of the doctrine, legislation and jurisprudence, is based on a predominantly dogmatic legal nature, in the analytical, empirical and regulatory dimensions. Following are the main conclusions: the right to life grated by the Federal Constitution structurally consists of a principle, with a broad protection scope, that justifies the need of weighting with other values protected by the legal legislation for its application; among the possible interpretations of what this right is consistent of, it can be considered as a right to the existence itself, a right to a decent life and a right to protection facing the development of the biotechnology; the beginning of the protection of the right to human embryo-based stem cell research and therapies are set in the Brazilian Law by national and international precepts, such as the American Convention of Human Rights, the Federal Constitution and the Law nº 11.105/2005; the fact that the Federal Supreme Court considered the Article 5 of Law nº 11.105/2005, in the concentrated model of constitutional control, did not distract the application of the American Convention of Human Rights (which contains the regulations that protects the right to life, in general, from its conception) neither obstructed an actual state or international control on the human embryo-based stem cell research and therapies in order to protect, among other aspects, the right to life in a transindividual approach.
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Zabihi, Sheller. "Fetal Outcome in Experimental Diabetic Pregnancy". Doctoral thesis, Uppsala University, Department of Medical Cell Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8739.
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Women with pregestational diabetes have a 2-5 fold increased risk of giving birth to malformed babies compared with non-diabetic women. Diabetes-induced oxidative stress in maternal and embryonic tissues has been implicated in the teratogenic process. The malformations are likely to be induced before the seventh week of pregnancy, when the yolk sac is partly responsible for the transfer of metabolites to the embryo, and the uterine blood flow to the implantation site determines the net amount of nutrients available to the conceptus. We aimed to evaluate the effect on embryogenesis caused by a diabetes-induced disturbance in yolk sac morphology, uterine blood flow or altered maternal antioxidative status in conjunction with a varied severity of the maternal diabetic state.
We investigated to which extent maternal diabetes with or without folic acid (FA) supplementation affects mRNA levels and protein distribution of ROS scavenging enzymes (SOD, CAT, GPX), vascular endothelial growth factor-A (Vegf-A), folate binding protein-1 (Folbp-1), and apoptosis associated proteins (Bax, Bcl-2, Caspase-3) in the yolk sacs of rat embryos on gestational days 10 and 11. We found that maternal diabetes impairs, and that FA supplementation restores, yolk sac vessel morphology, and that maternal diabetes is associated with increased apoptotic rate in embryos and yolk sacs, as well as impaired SOD gene expression. We assessed uterine blood flow with a laser-Doppler-flow-meter and found increased blood flow to implantation sites of diabetic rats compared with controls. Furthermore, resorbed and malformed offspring showed increased and decreased blood flow to their implantation sites, respectively. In mice with genetically altered CuZnSOD levels, maternal diabetes increased embryonic dysmorphogenesis irrespective of CuZnSOD expression. We thus found the maternal diabetic state to be a major determinant of diabetic embryopathy and that the CuZnSOD status exerts a partial protection for the embryo in diabetic pregnancy.
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Cimafranca, Melissa Antonio. "2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and epidermal growth factor (EGF) signaling inhibits in vitro adipogenesis in the mouse embryo fibroblast cell line C3H10T1/2". 2006. http://catalog.hathitrust.org/api/volumes/oclc/85783754.html.
Texto completo da fonteLivros sobre o assunto "2 cell-Embryo"
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1942-, Harris Stephen E., e Mansson Per-Erik, eds. Cellular factors in development and differentiation: Embryos, teratocarcinomas, and differentiated tissues : proceedings of the Third International Symposium on Cellular Endocrinology, held at Lake Placid, New York, August 30-September 2, 1987. New York: Liss, 1988.
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United States. Congress. Senate. Committee on Appropriations. Subcommittee on Departments of Labor, Health and Human Services, Education, and Related Agencies. Stem cell research: Hearings before a subcommittee of the Committee on Appropriations, United States Senate, One Hundred Fifth Congress, second session, special hearing, December 2, 1998, Washington DC, January 12, 1999, Washington DC, January 26, 1999, Washington DC. Washington: U.S. G.P.O., 1999.
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Germ cell protocols. Vol. 2, Molecular embryo analysis, live imaging, transgenesis, and cloning. Totowa, NJ: Humana Press, 2003.
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Germ Cell Protocols : Volume 2: Molecular Embryo Analysis, Live Imaging, Transgenesis, and Cloning. Humana Press, 2004.
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Schatten, Heide. Germ Cell Protocols: Volume 2: Molecular Embryo Analysis, Live Imaging, Transgenesis, and Cloning (Methods in Molecular Biology). Humana Press, 2004.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "2 cell-Embryo"
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Kong, Qingran, e Zhonghua Liu. "Electrofusion of 2-Cell Embryos for Porcine Tetraploid Embryo Production". In Methods in Molecular Biology, 361–71. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-8831-0_21.
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Lefèvre, Annick, e Thierry Blachère. "Methylation of Specific Regions: Bisulfite-Sequencing at the Single Oocyte or 2-Cell Embryo Level". In Methods in Molecular Biology, 209–26. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1594-1_16.
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Fielmich, Lars-Eric, e Sander van den Heuvel. "Polarity Control of Spindle Positioning in the C. elegans Embryo". In Cell Polarity 2, 119–41. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14466-5_5.
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Malerczyk, Claudius, e Helmut Müller. "Purified Chick-Embryo Cell Vaccine". In Current Laboratory Techniques in Rabies Diagnosis, Research and Prevention, Volume 2, 251–60. Elsevier, 2015. http://dx.doi.org/10.1016/b978-0-12-801919-1.00020-8.
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Ettensohn, Charles A., Kirsten A. Guss, Katherine M. Malinda, Roberta N. Miller e Seth W. Ruffins. "Cell Interactions in the Sea Urchin Embryo". In Advances in Developmental Biochemistry, 47–98. Elsevier, 1996. http://dx.doi.org/10.1016/s1064-2722(08)60057-2.
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Slack, Jonathan. "2. Embryonic stem cells". In Stem Cells: A Very Short Introduction, 21–37. Oxford University Press, 2021. http://dx.doi.org/10.1093/actrade/9780198869290.003.0002.
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‘Embryonic stem cells’ focuses on embryonic stem (ES) cells, which are grown in tissue culture from the inner cell mass of a mammalian blastocyst-stage embryo. Human ES cells offer a potential route to making the kinds of cells needed for cell therapy. ES cells were originally prepared from mouse embryos. Although somewhat different, cells grown from inner cell masses of human embryos share many properties with mouse ES cells, such as being able to grow without limit and to generate differentiated cell types. Mouse ES cells have so far been of greater practical importance than those of humans because they have enabled a substantial research industry based on the creation of genetically modified mice.
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Giordano, Simona. "Cloning". In Routledge Encyclopedia of Philosophy. London: Routledge, 2020. http://dx.doi.org/10.4324/9780415249126-l142-2.
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‘Cloning’ is the popular name given to Cell Nuclear Replacement (CNR) (also sometimes referred to as Cell Nuclear Transfer (CNT)). CNR involves a recipient cell, generally an egg (oocyte), and a donor cell. The nucleus of the donor cell is introduced into the oocyte. With appropriate stimulation the oocyte is induced to develop. Once the embryo is created, stem cells can be harvested from it for research purposes or for cell therapy (therapeutic cloning). The embryo might also be implanted into a viable womb and developed to term (reproductive cloning). The first mammal to be born by CNR was Dolly the sheep (1996–2003). CNR may have various potential applications ranging from reproduction to treatment of diseases such as cancer, Alzheimer’s, Parkinson’s disease, and spinal cord injuries. Although research on CNR is still relatively in its infancy, CNR (cloning) has attracted people’s attention in a way that few other advances in biomedical research do. To date, human reproductive cloning of an entire genome, as in the case of Dolly, has either been banned or has not been voluntarily undertaken anywhere in the world, so there is no reliable data on safety or efficacy of human reproductive cloning. However, public debate on whether or not human reproductive cloning would be ethical in principle has unfortunately been influenced more by fiction than science. The horrendous or absurd scenarios pictured in novels and films are sometimes mistakenly believed to be possible, or even likely, outcomes of cloning. Immediately after news of the birth of Dolly, the international community imposed restrictions particularly to human reproductive cloning, which is now virtually everywhere prohibited. Reproductive cloning is considered offensive to human dignity and a threat to the well-being of the child. Against therapeutic cloning objections are also raised. The strongest are that CNR involves the creation and destruction of embryos. The debate on the moral status of the embryo is ongoing, in bioethics, philosophy, and theology. However, if arguments against the killing of the embryo were to be accepted, then the current legal and social context of most European countries would have to be revised, and abortion and in vitro fertilisation (IVF) made criminal offences. Those who believe that abortion, even just in its therapeutic form, and IVF are acceptable, admit that it may be ethical to destroy an embryo either to save a life or to treat infertility. If this is accepted, it is unclear why it is unacceptable that embryos or embryonic material be used to treat serious and lethal diseases.
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Jeske, Mandy, e Elmar Wahle. "Chapter 6 Cell‐Free Deadenylation Assays with Drosophila Embryo Extracts". In Methods in Enzymology, 107–18. Elsevier, 2008. http://dx.doi.org/10.1016/s0076-6879(08)02606-2.
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Johnson, Randall, e Nigel Killeen. "Gene targeting in mammalian cells". In Gene probes 2, 1–30. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780199634156.003.0012.
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Abstract A wide variety of techniques has been employed to inhibit the expression of specific genes selectively in mammalian cells. This is a useful experimental option because by depriving a cell of a given gene product, one can often obtain invaluable information about the function of the gene. As a highly specific means for achieving gene-ablation, the targeted mutagenesis of endogenous chromosomal genes by homologous recombination (gene targeting) has recently become a widely used technique (1-4). Embryo-derived stem (ES) cells have been used in the majority of such experiments, since these cells offer the researcher the opportunity to pass the mutation from tissue culture to the mouse germline and, therefore, they allow for the phenotypic analysis to be conducted in vivo (5, 6).
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Köhler, Almut, Alexandra Schambony e Doris Wedlich. "Cell migration under control of Wnt‐signaling in the vertebrate embryo". In Wnt Signaling in Embryonic Development, 159–201. Elsevier, 2007. http://dx.doi.org/10.1016/s1574-3349(06)17005-2.
Texto completo da fonteTrabalhos de conferências sobre o assunto "2 cell-Embryo"
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Koloskova, E. M., V. A. Ezerskii e T. P. Trubitsina. "Effect of microinjection of CRISPR / Cas9 components in plasmid form on the development of rabbit embryos during in vitro culture". In CURRENT STATE, PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF AGRARIAN SCIENCE. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2020. http://dx.doi.org/10.33952/2542-0720-2020-5-9-10-131.
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The survival rate of rabbit embryos microinjected by the plasmid form of CRISPR/Cas9 components specific to the sour whey protein gene was evaluated. At high concentrations of plasmid components, embryo survival decreased slightly, possibly because the WAP gene does not belong to the housekeeping genes. After microinjection of a genetic construct with a sequence of green fluorescent protein under a cytomegalovirus promoter, the embryo survival significantly decreased. This is most likely due to the superexpression of GFP at the 2-16 cell stage of development.
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Nerurkar, Nandan L., e Cliff J. Tabin. "Collective Cell Movements Drive Morphogenesis and Elongation of the Avian Hindgut". In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14438.
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At the end of gastrulation, the endoderm forms a single-cell thick epithelium lining the ventral surface of the developing embryo. Subsequently, through a series of poorly understood events, the initially flat endoderm is transformed into the gut tube, a cylindrical structure that gives rise to the epithelial lining of the entire respiratory and gastrointestinal tracts. In birds and mammals, formation of the gut tube begins with two invaginations at the anterior (head) and posterior (tail) poles of the embryo, termed the anterior (AIP) and caudal intestinal portals (CIP). It is thought that the AIP and CIP begin moving toward one another as two progressing waves of lateral-to medial folding (from left and right toward center), “zipping” the gut tube closed along the embryonic midline (Fig. 1A). This view of lateral-to-medial folding is, however, inconsistent with several observations. For example, fate mapping studies in chick and mouse that suggest that cells originating in the posterior end (toward the tail) of the flat endoderm do not form the hindgut, but instead contribute to the more anterior midgut [1, 2]. This would not be possible in a simple lateral-to-medial folding process. Therefore, it is largely unknown how this fundamental structure of the vertebrate body plan is established. The objective of the present work is to apply multi-photon live imaging of the chick embryo to determine how the hindgut is formed. Our findings suggest the hindgut arises from directed, collective cell movements that drive antero-posterior folding of the initially flat endoderm.
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Pehl-De Silva, Aruni T., Preethi Samala, Hongkyu Lee e Joseph R. Landolph. "Abstract 3466: Increased steady-state levels of microtubules in aberrant distributions in Ni+2ion-/MCA-transformed C3H/10T1/2 mouse embryo cell lines". In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-3466.
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Filas, Benjamen A., Gang Xu, Andrew K. Knutsen, Philip V. Bayly e Larry A. Taber. "Morphogenetic and Residual Strains in the Embryonic Chick Brain". In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-191781.
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The brain of the chick embryo first becomes a fully sealed tube containing embryonic cerebrospinal fluid (ECSF) at Hamburger and Hamilton [1] stage 11 (HH11, approximately 42 hours of a 21-day incubation period). During the subsequent 40 hours of development, the brain undergoes dramatic changes in size and shape in response to increases in luminal pressure [2]. These changes include local regions that bulge outwards to create the primitive forebrain, midbrain, and hindbrain. While it has been shown that the internal ECSF can regulate cell proliferation and neurogenesis [3] in early brain development, possible biophysical factors contributing to this process have not been well characterized.
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Yao, Jiang, Jonathan M. Young, Benjamen A. Filas, Nils Klinkenberg, Jincheng Wang, Larry A. Taber e Renato Perucchio. "Finite Element Modeling of the Tubular Embryonic Chick Heart With Smoothed Surfaces and Contact With Splanchnopleure Membrane". In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206466.
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During cardiac development, the initially straight heart tube bends ventrally and rotates towards the right side of the embryo. The biomechanical mechanism of cardiac looping is still unclear, but it has been hypothesized to be related to the unbalanced forces in the left and right omphalomesenteric veins (OVs) generated by cytoskeletal contraction and cell migration, as well as contact with the Splanchnopleure (SPL), a membrane which is located at the ventral surface of the heart and wraps around the OV at the anterior intestinal portal (AIP) [1]. To test this hypothesis, a computational model is a powerful tool. The objective of this study is to generate a finite element model (FEM) with realistic geometry of the tubular heart with the OVs in its caudal ends, which contacts with the SPL. In alternative to the voxel based model, as explored by Young et al. [2], we study issues related to a model with smoothed surfaces, and its capacity in dealing with nonlinear material, large deformation and contact. Although heart looping proceeds normally without pressure generated from heart beat [3], we applied an internal pressure to test the model.
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Hart, Stephen A., e Marcelo J. Dapino. "Accelerated Bone Growth Remotely Induced by Magnetic Fields and Smart Materials". In ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-175966.
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Bone structure is exquisitely matched to its physical loading environment. From the cartilaginous skeletal framework formed in the embryo to the aging skeleton, bone architecture is directly related to function. Bone is a dynamic system, constantly remodeling itself by absorbing old tissue and forming new tissue. This capability allows bone architecture to become optimized to the loading environment. Julius Wolff [1] first postulated that bone structure adapts to changing stress environments in 1892. Exact understanding of the process of mechanotransduction, however, has remained elusive. In addition to normal remodeling, bone growth has been shown to occur along the diaphysis, or shaft portion, of long bones such as the femur when placed in dynamic bending. Bone in this region is dense and is known as cortical bone. A bending moment placed on a long bone will cause the bone to curve creating a region of tension on one side and a region of compression on the opposing side. As the bending moment is cycled, fluid within the bone will flow from the region of compression to the region of tension creating fluid shear on cell walls within the bone which promotes the anabolic response of growth [2]. Growth from such stimuli is thought to be mediated by fluid flow around quiescent bone cells, osteocytes, and their canalicular process coursing through the bone structure [3]. Growth in this manner is directed in a latitudinal direction creating a thicker and stronger diaphysis.
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Chun, Young Wook, Joey Barnett e W. David Merryman. "Aortic Valve Interstitial Cell Activation Does Not Occur at Low Tissue Stiffness During Embryogenesis". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80501.
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An estimated 2.5 percent of the American population has heart valve (HV) disease and more than 100,000 US patients require a prosthetic valve replacement each year [1]. However, prosthetic valves can cause accelerated calcification leading to recurrence of HV disease in patients [2]. Thus, the development of a suitable tissue-engineered heart valve (TEHV) would greatly benefit patients with HV disease. Aortic valve interstitial cells (AVICs) play a crucial role in the progression of aortic valve disease as well as the maintenance of normal valve. Therefore, in order to design a suitable TEHV, these specialized cells need to be better understood. AVICs are known to synthesize ECM and express matrix degrading enzymes and their inhibitors that mediate and regulate remodeling of ECM components [3]. Interestingly, it was recently established that AVICs sense the stiffness of their surrounding ECM in vivo and are phenotypically responsive to mechanical cues with AVICs differentiating into myofibroblasts or osteoblasts, which are pathologic markers. Specifically, soft collagen gels (∼34kPa) caused less differentiation of AVICs than stiffer collagen gel (∼100kPa) [4]. However, for these experiments the AVICs were cultured on tissue culture polystyrene (TCPS) for at least one passage, and it is likely that AVICs cultured on TCPS might retain modified characteristics of AVICs in tissue prior to seed them on soft gels because of the memory to rigid substrate stiffness. Therefore, in this study, we examined the phenotype and function of AVICs on substrates that mimic ECM stiffness of adult leaflet as well as of developing embryo. In addition, we examine the effects of transforming growth factor-β1 (TGF-β1) which has been the most extensively studied cytokine initiator of fibrotic response of AVICs.
Relatórios de organizações sobre o assunto "2 cell-Embryo"
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Petitte, James, Hefzibah Eyal-Giladi e Malka Ginsburg. The Study of Primordial Germ Cell Development as a Tool for Gene Transfer in Chickens. United States Department of Agriculture, outubro de 1991. http://dx.doi.org/10.32747/1991.7561071.bard.
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The ability to introduce novel genetic material into the genome of commercial poultry has been impeded by a lack of kowledge regarding the origin in the early embryo of the target cell of interest, namely, the germ cell. Hence, this project investigated the emergence of primordial germ cells (PGCs) during the early development of the avian embryo to aid in efforts to produce transgenic poultry on a routine basis. The strategy was to introduce foreign DNA into the area of the unincubated embryo that is destined to give rise to the germ line. The objectives of this project were: 1) to identify and localize a subpopulation of cells in the early embryo which will give rise to PGCs, 2) to determine the best location and stage of development to transfer donor cells for efficient germline chimerism, and 3) to transfect donor cells to produce transgenic/germline chimeric embryos. We show that by using the monoclonal antibody SSEA-1 and by various cell culture techniques that germ cells appear to segregate from the somatic lineages at St. X., a process that is gradual and continues through St. XIV. Using microsurgical transplantation between quail and chick embryos, we demonstrated that the inner 1/3 of the area pellucida between states X-XII gives rise to about 2/3 of the germ cell population at the time of their residence in the germinal crescent. Because of the non-localized emergence of PGCs, attempts to introduce foreign DNA into clonal precursors of germ cells through liposome-mediated transfection yielded unacceptable levels of efficiency. However, through our investigation of germ cell origins, an in vitro model of germ cell differentiation was developed that could offer a means of determining the factors required for the long term culture of avian PGCs thereby providing a convenient means of manipulating the avian genome.
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Halevy, Orna, Zipora Yablonka-Reuveni e Israel Rozenboim. Enhancement of meat production by monochromatic light stimuli during embryogenesis: effect on muscle development and post-hatch growth. United States Department of Agriculture, junho de 2004. http://dx.doi.org/10.32747/2004.7586471.bard.
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The original objectives were: A. To determine the critical embryonic age for monochromatic green light stimulation. B. To follow the ontogeny of embryos exposed to monochromatic green light vs. darkness. C. To investigate the effects of monochromatic green light illumination on myoblast and fiber development in the embryo. D. To investigate the stimulatory effect of light combinations during embryo and post-hatch periods on growth and meat production. E. To evaluate the direct effect of monochromatic green light on cultured embryonic and adult myoblasts. The overall purpose of this study was to investigate the effect of monochromatic light stimuli during incubation period of broilers on muscle development and satellite cell myogenesis. Based on previous studies (Halevy et al., 1998; Rozenboim et al., 1999) that demonstrated the positive effects of green-light illumination on body and muscle growth, we hypothesized that monochromatic light illumination accelerates embryo and muscle development and subsequently enhances muscle growth and meat production. Thus, further decreases management costs. Under the cooperation of the laboratories at the Hebrew University of Jerusalem and University of Washington we have conducted the following: 1. We have established the critical stage for exposure to green monochromatic light which has the maximal effect on body and muscle growth (Objective A). We report that embryonic day 5 is optimal for starting illumination. The optimal regime of lighting that will eliminate possible heat effects was evaluated by monitoring egg core temperature at various illumination periods. We found that intermitted lighting (15 min. on; 15 min. off) is optimal to avoid heat effects. 2. We have evaluated in detail gross changes in embryo development profile associated to green light stimuli vs. darkness. In addition, we have investigated the stimulatory effect of light combinations during embryo and post-hatch periods on body and muscle growth (Objective B,D). 3. We have studied the expression profile of muscle regulatory proteins during chicken muscle cell differentiation in cultures using newly developed antibodies. This study paved the way for analyzing the expression of these proteins in our photo stimulation experiments (Objective C). 4. We have studied the pattern ofPax7 expression during myogenesis in the posthatch chicken. Experimental chick pectoralis muscles as well adult myoblast cultures were used in this study and the results led us to propose a novel model for satellite cell differentiation and renewal. 5. The effects of monochromatic green light illumination during embryogenesis have been studied. These studies focused on fetal myoblast and satellite cell proliferation and differentiation at pre- and posthatch periods and on the effects on the expression of muscle regulatory proteins which are involved in these processes. In addition, we have analyzed the effect of photo stimulation in the embryo on myofiber development at early posthatch (Objective C). 6. In follow the reviewers' comments we have not conducted Objective E. The information gathered from these studies is of utmost importance both, for understanding the molecular basis of muscle development in the posthatch chicks and for applied approach for future broiler management. Therefore, the information could be beneficial to agriculture in the short term on the one hand and to future studies on chick muscle development in the embryo and posthatch on the other hand.
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Hansen, Peter J., e Zvi Roth. Use of Oocyte and Embryo Survival Factors to Enhance Fertility of Heat-stressed Dairy Cattle. United States Department of Agriculture, agosto de 2011. http://dx.doi.org/10.32747/2011.7697105.bard.
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The overall goal was to identify survival factors that can improve pregnancy success following insemination or embryo transfer in lactating dairy cows exposed to heat stress. First, we demonstrated that oocytes are actually damaged by elevated temperature in the summer. Then we tested two thermoprotective molecules for their effect on oocyte damage caused by heat shock. One molecule, ceramide was not thermoprptective. Another, insulin-like growth factor-1 (IGF) reduced the effects of heat shock on oocyte apoptosis and oocyte cleavage when added during maturation. We also used lactating cows exposed to heat stress to determine whether bovine somatotropin (bST), which increases IGF1 levels in vivo, would improve fertility in summer. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p =0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control). Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows. In another experiment, we found a tendency for addition of IGF1 to embryo culture medium to improve embryonic survival after embryo transfer when the experiment was done during heat stress but not when the experiment was done in the absence of heat stress. Another molecule tested, granulocyte-macrophage colony-stimulating factor (GM-CSF; also called colony-stimulating factor-2), improved embryonic survival in the absence of heat stress. We also examined whether heat shock affects the sperm cell. There was no effect of heat shock on sperm apoptosis (programmed cell death) or on sperm fertilizing ability. Therefore, effects of heat shock on sperm function after ejaculation if minimal. However, there were seasonal changes in sperm characteristics that indicates that some of the decrease in dairy cow fertility during the summer in Israel is due to using semen of inferior quality. Semen was collected from five representative bulls throughout the summer (August and September) and winter (December and January). There were seasonal differences in ion concentration in seminal plasma and in the mRNA for various ion channels known to be involved in acrosome reactions. Furthermore, the proportion of sperm cells with damaged acrosomes was higher in post-thaw semen collected in the summer than in its counterpart collected in winter (54.2 ± 3.5% vs. 51.4 ± 1.9%, respectively; P < 0.08Further examination is required to determine whether such alterations are involved in the low summer fertility of dairy cows.
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Ohad, Nir, e Robert Fischer. Regulation of Fertilization-Independent Endosperm Development by Polycomb Proteins. United States Department of Agriculture, janeiro de 2004. http://dx.doi.org/10.32747/2004.7695869.bard.
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Arabidopsis mutants that we have isolated, encode for fertilization-independent endosperm (fie), fertilization-independent seed2 (fis2) and medea (mea) genes, act in the female gametophyte and allow endosperm to develop without fertilization when mutated. We cloned the FIE and MEA genes and showed that they encode WD and SET domain polycomb (Pc G) proteins, respectively. Homologous proteins of FIE and MEA in other organisms are known to regulate gene transcription by modulating chromatin structure. Based on our results, we proposed a model whereby both FIE and MEA interact to suppress transcription of regulatory genes. These genes are transcribed only at proper developmental stages, as in the central cell of the female gametophyte after fertilization, thus activating endosperm development. To test our model, the following questions were addressed: What is the Composition and Function of the Polycomb Complex? Molecular, biochemical, genetic and genomic approaches were offered to identify members of the complex, analyze their interactions, and understand their function. What is the Temporal and Spatial Pattern of Polycomb Proteins Accumulation? The use of transgenic plants expressing tagged FIE and MEA polypeptides as well as specific antibodies were proposed to localize the endogenous polycomb complex. How is Polycomb Protein Activity Controlled? To understand the molecular mechanism controlling the accumulation of FIE protein, transgenic plants as well as molecular approaches were proposed to determine whether FIE is regulated at the translational or posttranslational levels. The objectives of our research program have been accomplished and the results obtained exceeded our expectation. Our results reveal that fie and mea mutations cause parent-of-origin effects on seed development by distinct mechanisms (Publication 1). Moreover our data show that FIE has additional functions besides controlling the development of the female gametophyte. Using transgenic lines in which FIE was not expressed or the protein level was reduced during different developmental stages enabled us for the first time to explore FIE function during sporophyte development (Publication 2 and 3). Our results are consistent with the hypothesis that FIE, a single copy gene in the Arabidopsis genome, represses multiple developmental pathways (i.e., endosperm, embryogenesis, shot formation and flowering). Furthermore, we identified FIE target genes, including key transcription factors known to promote flowering (AG and LFY) as well as shoot and leaf formation (KNAT1) (Publication 2 and 3), thus demonstrating that in plants, as in mammals and insects, PcG proteins control expression of homeobox genes. Using the Yeast two hybrid system and pull-down assays we demonstrated that FIE protein interact with MEA via the N-terminal region (Publication 1). Moreover, CURLY LEAF protein, an additional member of the SET domain family interacts with FIE as well. The overlapping expression patterns of FIE, with ether MEA or CLF and their common mutant phenotypes, demonstrate the versatility of FIE function. FIE association with different SET domain polycomb proteins, results in differential regulation of gene expression throughout the plant life cycle (Publication 3). In vitro interaction assays we have recently performed demonstrated that FIE interacts with the cell cycle regulatory component Retinobalsoma protein (pRb) (Publication 4). These results illuminate the potential mechanism by which FIE may restrain embryo sac central cell division, at least partly, through interaction with, and suppression of pRb-regulated genes. The results of this program generated new information about the initiation of reproductive development and expanded our understanding of how PcG proteins regulate developmental programs along the plant life cycle. The tools and information obtained in this program will lead to novel strategies which will allow to mange crop plants and to increase crop production.
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Yahav, Shlomo, John Brake e Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, setembro de 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
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: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.