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Academic literature on the topic 'Prophase I'

Author: Grafiati

Published: 25 May 2024

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Journal articles on the topic "Prophase I"

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Rieder, Conly L., and Richard W. Cole. "Entry into Mitosis in Vertebrate Somatic Cells Is Guarded by a Chromosome Damage Checkpoint That Reverses the Cell Cycle When Triggered during Early but Not Late Prophase." Journal of Cell Biology 142, no. 4 (August 24, 1998): 1013–22. http://dx.doi.org/10.1083/jcb.142.4.1013.

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When vertebrate somatic cells are selectively irradiated in the nucleus during late prophase (<30 min before nuclear envelope breakdown) they progress normally through mitosis even if they contain broken chromosomes. However, if early prophase nuclei are similarly irradiated, chromosome condensation is reversed and the cells return to interphase. Thus, the G2 checkpoint that prevents entry into mitosis in response to nuclear damage ceases to function in late prophase. If one nucleus in a cell containing two early prophase nuclei is selectively irradiated, both return to interphase, and prophase cells that have been induced to returned to interphase retain a normal cytoplasmic microtubule complex. Thus, damage to an early prophase nucleus is converted into a signal that not only reverses the nuclear events of prophase, but this signal also enters the cytoplasm where it inhibits e.g., centrosome maturation and the formation of asters. Immunofluorescent analyses reveal that the irradiation-induced reversion of prophase is correlated with the dephosphorylation of histone H1, histone H3, and the MPM2 epitopes. Together, these data reveal that a checkpoint control exists in early but not late prophase in vertebrate cells that, when triggered, reverses the cell cycle by apparently downregulating existing cyclin-dependent kinase (CDK1) activity.

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Wang, Tianzuo, Mengya Xue, Peng Sha, Fei Xue, and Linxiang Wang. "Study on the Influence of Different Prophase Stress Levels on the Fatigue Damage Characteristics of Granite." Shock and Vibration 2021 (June 5, 2021): 1–12. http://dx.doi.org/10.1155/2021/5513910.

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In order to reveal the influence of prophase stress levels on the fatigue damage characteristics of granite, uniaxial fatigue tests of granite with different prophase stress levels were carried out on the basis of the MTS 815.04 rock mechanics test system. The results show that, under the same number of cycles, the failure degree increases with the increase of the prophase stress level. Under the low upper limit of cyclic stress, the tangent modulus and dissipated energy increase significantly with the increase of prophase stress level at the early stage of the cycle loading, while the increasing trend is not obvious with the increase of prophase stress level at the late stage. Under the high upper limit of cyclic stress, the tangent modulus and dissipated energy are less affected by the prophase stress level. The development trend of elastic release energy is not obvious with the increase of prophase stress level, which is less affected by the number of cycles. From the damage parameters defined by dissipative energy, under the low upper limit of cyclic stress, the initial damage is less affected by the prophase stress level. With the increase of the number of cycles, the influence of the prophase stress level on the development trend of the damage variable increases gradually. And the development trend of damage variables shows “C-shaped” damage.

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Fellmeth, Jessica E., Janet K. Jang, Manisha Persaud, Hannah Sturm, Neha Changela, Aashka Parikh, and Kim S. McKim. "A dynamic population of prophase CENP-C is required for meiotic chromosome segregation." PLOS Genetics 19, no. 11 (November 29, 2023): e1011066. http://dx.doi.org/10.1371/journal.pgen.1011066.

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The centromere is an epigenetic mark that is a loading site for the kinetochore during meiosis and mitosis. This mark is characterized by the H3 variant CENP-A, known as CID in Drosophila. In Drosophila, CENP-C is critical for maintaining CID at the centromeres and directly recruits outer kinetochore proteins after nuclear envelope break down. These two functions, however, happen at different times in the cell cycle. Furthermore, in Drosophila and many other metazoan oocytes, centromere maintenance and kinetochore assembly are separated by an extended prophase. We have investigated the dynamics of function of CENP-C during the extended meiotic prophase of Drosophila oocytes and found that maintaining high levels of CENP-C for metaphase I requires expression during prophase. In contrast, CID is relatively stable and does not need to be expressed during prophase to remain at high levels in metaphase I of meiosis. Expression of CID during prophase can even be deleterious, causing ectopic localization to non-centromeric chromatin, abnormal meiosis and sterility. CENP-C prophase loading is required for multiple meiotic functions. In early meiotic prophase, CENP-C loading is required for sister centromere cohesion and centromere clustering. In late meiotic prophase, CENP-C loading is required to recruit kinetochore proteins. CENP-C is one of the few proteins identified in which expression during prophase is required for meiotic chromosome segregation. An implication of these results is that the failure to maintain recruitment of CENP-C during the extended prophase in oocytes would result in chromosome segregation errors in oocytes.

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Walters, Marta Sherman. "Meiosis readiness in Lilium." Canadian Journal of Genetics and Cytology 27, no. 1 (February 1, 1985): 33–38. http://dx.doi.org/10.1139/g85-007.

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It was observed in five cultivars and two hybrids of Lilium that premeiotic prophase is retarded in anthers approaching meiosis. The occurrence of premeiotic despiralization was related to the degree of retardation of premeiotic prophase. It is proposed that meiosis is initiated by stimuli arising outside the premeiotic cells. It is suggested that an accumulation of meiosis-inducing substances in the cytoplasm of the premeiotic cells causes prophase to slow down; when a critical level ("meiosis readiness") is reached, mitotic division is no longer possible and cells in premeiotic prophase despiralize to interphase.Key words: meiotic prophase, Lilium, meiotic readiness, premeiotic despiralization.

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Kireeva, Natashe, Margot Lakonishok, Igor Kireev, Tatsuya Hirano, and Andrew S. Belmont. "Visualization of early chromosome condensation." Journal of Cell Biology 166, no. 6 (September 7, 2004): 775–85. http://dx.doi.org/10.1083/jcb.200406049.

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Current models of mitotic chromosome structure are based largely on the examination of maximally condensed metaphase chromosomes. Here, we test these models by correlating the distribution of two scaffold components with the appearance of prophase chromosome folding intermediates. We confirm an axial distribution of topoisomerase IIα and the condensin subunit, structural maintenance of chromosomes 2 (SMC2), in unextracted metaphase chromosomes, with SMC2 localizing to a 150–200-nm-diameter central core. In contrast to predictions of radial loop/scaffold models, this axial distribution does not appear until late prophase, after formation of uniformly condensed middle prophase chromosomes. Instead, SMC2 associates throughout early and middle prophase chromatids, frequently forming foci over the chromosome exterior. Early prophase condensation occurs through folding of large-scale chromatin fibers into condensed masses. These resolve into linear, 200–300-nm-diameter middle prophase chromatids that double in diameter by late prophase. We propose a unified model of chromosome structure in which hierarchical levels of chromatin folding are stabilized late in mitosis by an axial “glue.”

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Hajeri, Vinita A., Brent A. Little, Mary L. Ladage, and Pamela A. Padilla. "NPP-16/Nup50 Function and CDK-1 Inactivation Are Associated with Anoxia-induced Prophase Arrest in Caenorhabditis elegans." Molecular Biology of the Cell 21, no. 5 (March 2010): 712–24. http://dx.doi.org/10.1091/mbc.e09-09-0787.

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Oxygen, an essential nutrient, is sensed by a multiple of cellular pathways that facilitate the responses to and survival of oxygen deprivation. The Caenorhabditis elegans embryo exposed to severe oxygen deprivation (anoxia) enters a state of suspended animation in which cell cycle progression reversibly arrests at specific stages. The mechanisms regulating interphase, prophase, or metaphase arrest in response to anoxia are not completely understood. Characteristics of arrested prophase blastomeres and oocytes are the alignment of condensed chromosomes at the nuclear periphery and an arrest of nuclear envelope breakdown. Notably, anoxia-induced prophase arrest is suppressed in mutant embryos lacking nucleoporin NPP-16/NUP50 function, indicating that this nucleoporin plays an important role in prophase arrest in wild-type embryos. Although the inactive form of cyclin-dependent kinase (CDK-1) is detected in wild-type–arrested prophase blastomeres, the inactive state is not detected in the anoxia exposed npp-16 mutant. Furthermore, we found that CDK-1 localizes near chromosomes in anoxia-exposed embryos. These data support the notion that NPP-16 and CDK-1 function to arrest prophase blastomeres in C. elegans embryos. The anoxia-induced shift of cells from an actively dividing state to an arrested state reveals a previously uncharacterized prophase checkpoint in the C. elegans embryo.

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Wang, Jianyue, and Feixiong Zhang. "Nucleolus disassembly and distribution of segregated nucleolar material in prophase of root-tip meristematic cells in Triticum aestivum L." Archives of Biological Sciences 67, no. 2 (2015): 405–10. http://dx.doi.org/10.2298/abs140810007w.

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This paper presents details of the process of nucleolar disassembly, studied by conventional transmission electron microscopy (TEM) in wheat root cells. In early prophase, chromatin condensation and irregular nucleolar morphology are observed, with many small particles appearing around the nucleolus. In middle prophase, the nucleolus radiates outwards; in late prophase, the fine structure of the nucleolus disappears and nucleolar material diffuses away. Using ?en bloc? silver-staining to distinguish between nucleoli and chromatin, we observed that the dispersed nucleolar material aggregates around the chromatin, forming a sheath-like perichromosomal structure that coats the chromosomes in late prophase.

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Láscarez-Lagunas, Laura, Marina Martinez-Garcia, and Mónica Colaiácovo. "SnapShot: Meiosis – Prophase I." Cell 181, no. 6 (June 2020): 1442–1442. http://dx.doi.org/10.1016/j.cell.2020.04.038.

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Fan, Xueying, Ioannis Moustakas, Vanessa Torrens-Juaneda, Qijing Lei, Geert Hamer, Leoni A. Louwe, Gonneke S. K. Pilgram, et al. "Transcriptional progression during meiotic prophase I reveals sex-specific features and X chromosome dynamics in human fetal female germline." PLOS Genetics 17, no. 9 (September 9, 2021): e1009773. http://dx.doi.org/10.1371/journal.pgen.1009773.

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During gametogenesis in mammals, meiosis ensures the production of haploid gametes. The timing and length of meiosis to produce female and male gametes differ considerably. In contrast to males, meiotic prophase I in females initiates during development. Hence, the knowledge regarding progression through meiotic prophase I is mainly focused on human male spermatogenesis and female oocyte maturation during adulthood. Therefore, it remains unclear how the different stages of meiotic prophase I between human oogenesis and spermatogenesis compare. Analysis of single-cell transcriptomics data from human fetal germ cells (FGC) allowed us to identify the molecular signatures of female meiotic prophase I stages leptotene, zygotene, pachytene and diplotene. We have compared those between male and female germ cells in similar stages of meiotic prophase I and revealed conserved and specific features between sexes. We identified not only key players involved in the process of meiosis, but also highlighted the molecular components that could be responsible for changes in cellular morphology that occur during this developmental period, when the female FGC acquire their typical (sex-specific) oocyte shape as well as sex-differences in the regulation of DNA methylation. Analysis of X-linked expression between sexes during meiotic prophase I suggested a transient X-linked enrichment during female pachytene, that contrasts with the meiotic sex chromosome inactivation in males. Our study of the events that take place during meiotic prophase I provide a better understanding not only of female meiosis during development, but also highlights biomarkers that can be used to study infertility and offers insights in germline sex dimorphism in humans.

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Jessus, C., C. Thibier, and R. Ozon. "Levels of microtubules during the meiotic maturation of the Xenopus oocyte." Journal of Cell Science 87, no. 5 (June 1, 1987): 705–12. http://dx.doi.org/10.1242/jcs.87.5.705.

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The total level of tubulin and the ratio of polymeric tubulin to tubulin dimer were measured by a colchicine filter-binding assay during meiotic maturation of the Xenopus oocyte. Although the total level of tubulin remains unchanged (0.12 +/− 0.03 micrograms/oocyte), the level of polymeric tubulin decreases during maturation (25% in prophase oocytes versus 20% in metaphase oocytes). The percentage of polymerized tubulin was estimated after drug (nocodazole and taxol) treatments and cold treatment in prophase and progesterone-matured oocytes; in all cases the microtubules present in mature oocyte are less stable than prophase microtubules. The presence of the nucleus modifies neither the level nor the stability of prophase microtubules. Our quantitative results as well as cytological arguments suggest that full-grown Xenopus oocytes may contain a cortical microtubular array.

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Dissertations / Theses on the topic "Prophase I"

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Lee, Chih-ying. "Bouquet formation, rapid prophase movements and homologous pairing during meiotic prophase in Saccharomyces cerevisiae." Oklahoma City : [s.n.], 2009.

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Testori, Sarah. "Cohesin dynamics during meiotic prophase." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/29857.

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For faithful segregation during meiosis, chromosomes must be physically linked by both sister chromatid cohesion (SCC), provided by cohesin, and at least one crossover (CO). In mitosis, cohesin is dynamically associated with chromatin and this has been shown to be crucial for the repair of DSBs. Although DSBs are purposely made to start meiotic recombination, it is unknown if meiotic cohesin is dynamically associated with chromatin. However, cohesin loss or degradation is thought to be involved in the high incidence of aneuploidy observed in human eggs. In Caenorhabditis elegans (C. elegans), the cohesin loader SCC-2 remains associated with the axial element of meiotic chromosomes following the completion of S-phase, hinting that cohesin may be reloaded during meiotic prophase. To confirm this, I investigated if depleting SCC-2 by RNAi after entrance into meiotic prophase had an effect on cohesin association with chromosomes. This revealed loss of the cohesin subunit REC-8 from late prophase nuclei, suggesting that without reloading cohesin is removed from chromatin. Furthermore, scc-2 RNAi also resulted in the impairment of chiasmata, raising the possibility that cohesin reloading plays a role in CO formation or in chiasma maintenance. Two key mediators of cohesin removal are known to operate during the G2 phase of the mitotic cell cycle: the presence of DSBs and the cohesion anti-establishment factor Wapl1. Here I show for the first time that WAPL-1 modulates the cohesiveness of complexes containing the meiosis-specific kleisins COH-3 and COH-4. Furthermore, cohesin complexes containing different kleisins are differentially modulated by DSBs, and only REC-8-containing cohesin complexes can undertake the repair of DNA damage. Finally, I have developed several genetic tools to allow the visualization of cohesin turnover during meiosis. These findings show the exceptional complexity of cohesin dynamics during meiotic prophase, as well as demonstrating roles for cohesin outside of the provision of SCC.

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Ghafari, Fataneh. "Oocyte progression and death during first meiotic prophase." Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409952.

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Persico, Angela. "The Role of Golgi Fragmentation in the Regulation f G2/Prophase Transition." Thesis, Open University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520741.

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Crawley, Oliver. "Investigating the regulation of cohesin dynamics during meiotic prophase in C. elegans." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/44281.

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The physical linking of sister chromatids after S-phase is known as sister chromatid cohesion (SCC) and is largely provided by the cohesin complex. The coordinated loss of SCC at anaphase onset is essential for correct chromosome segregation, a process mediated by proteolysis of the kleisin subunit of cohesin. In addition, during mitotic prophase of most organisms a large portion of cohesin is removed from chromosomes by a non-proteolytic pathway that depends on the conserved protein WAPL. Cohesin is also known to reload and SCC is re-established in response to DSBs after mitotic S-phase. During meiosis, SCC is similarly established during S-phase, but is then released in two steps during the sequential meiotic divisions. Also, unlike mitosis, multiple cohesin complexes with divergent functions exist in meiosis. Whether cohesin is dynamically associated with chromosomes during meiotic prophase and how this may be regulated was not known. Thus, the key aims of this project were to determine if WAPL mediates cohesin removal during meiotic prophase, and to find out if meiotic cohesin complexes display turnover on prophase chromosomes of the nematode C. elegans. Alternative meiosis-specific kleisins (REC-8, COH-3, and COH-4) define the different complexes present during worm meiosis. I show here that WAPL-1 limits the association of COH-3/4 complexes with meiotic prophase chromosomes, which severely limits their cohesive function. REC-8 complexes on the other hand are not affected much by WAPL-1. I show that loss of WAPL-1 affects the structure of axial elements and disrupts chromosome segregation and DSB repair. I also demonstrate by FRAP live imaging that there is significant turnover of cohesin on meiotic prophase chromosomes. Dynamic turnover of COH-3 is much greater that REC-8, as predicted by the different sensitivity to WAPL-1 of REC-8 and COH-3 cohesin complexes. These findings demonstrate that cohesin is actively removed and reloaded during meiotic prophase. Dysregulation of these processes could be relevant for human fertility, since SCC exhaustion over time is thought to contribute to the decline in fertility with increased maternal age.

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Ene, Adriana. "Meiotic prophase progression and germ cell elimination in fetal and neonatal mouse ovaries." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92367.

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In most mammalian species, all oogonia cease mitotic proliferation and enter meiosis in fetal ovaries. Furthermore, more than half of the maximum number of germ cells is eliminated from ovaries by neonatal life, thus limiting the oocyte reserve for reproduction. The cause or mechanism of this female germ cell loss remains largely unknown. A major loss occurs in the oocytes which reach the pachytene stage of meiotic prophase, suggesting that oocytes with meiotic or recombination errors may be eliminated by a checkpoint mechanism. It remains to be determined whether oocytes are eliminated by apoptosis and if so in which pathway. The purpose of my study is to investigate a mechanism of oocyte loss in the mouse ovary during meiotic prophase. We used an Msh5 null mutant mouse strain, in which all oocytes are eliminated by neonatal life. Msh5 encodes a protein required for meiotic chromosome synapsis.
Msh5 heterozygous mutant mice were crossed and ovaries were isolated from female progeny at 14.5 22.5 days postcoitum (dpc). We studied the loss of germ cells in Msh5 -/- (MT) females comparing to the Msh5 +/+ (WT) and Msh5 (+/-) (HT) females by immunolabeling of ovarian sections for GCNA1 or MVH (both germ cell markers) or by counting GCNA1 positive germ cells in cell suspension preparations. Our results showed a continuous loss of GCNA1 positive cells in both MT and WT although the loss in MT was constantly larger than in the WT. A significant difference between WT and MT was found at 19.5 dpc.
Meiotic progression was studied by GCNA1 and SC (synaptonemal complex) or SC and ɣH2AX double immunolabeling of chromosome spread preparations. We found that meiosis in MT was blocked at zygotene-pachytene transition. No normal pachytene was observed in MT.
The role of apoptosis in elimination of oocytes during meiotic prophase was investigated by analyzing the cleavage of various caspases (caspase 2, 3, 6, 7, 9) as well as PARP1 by western blot using the lysate of whole ovaries. The activation of initiator caspase 9 increased from 17.5 to 18.5 dpc and decreased by 19.5 dpc. Caspase 2L activation also increased in a similar pattern but at much lower levels. The activation of effector caspase 3 or 6 remained at low levels. The activation of caspase 7 also was low but increased slightly at 19.5 dpc. The cleavage of PARP1 was high at all investigated stages. There were not major differences in the average level of activation between WT and MT. By immunolabeling of ovarian sections we observed that cleaved caspases and PARP1 were localized in oocytes but also in cells negative for GCNA1.
These results suggest that a mitochondrial pathway of apoptosis may play a role in the elimination of oocytes during meiotic prophase, involving activation of caspase 9 and cleavage of PARP1. However further studies are necessary for identification of an effector caspase.
Dans la plupart des espèces de mammifères, tous les oocytes cessent la prolifération mitotique et initialisent la méiose dans les ovaires ftales. En outre, plus de la moitié du nombre maximal de cellules germinales est éliminée dans les ovaires pendant la vie néonatale, limitant ainsi la réserve d'oocytes pour la reproduction. La cause ou le mécanisme de cette perte de cellules germinales femelles reste largement inconnu. Une perte majeure se produit dans les oocytes qui atteignent le stade pachytène de la prophase méiotique, suggérant que les oocytes avec des erreurs dans la méiose ou des erreurs de recombinaison peuvent être éliminés par un mécanisme de contrôle. Il reste à déterminer si les oocytes sont éliminés par apoptose, et si oui, par quel méchanisme. Le but de mon projet est d'étudier un mécanisme de perte d'oocytes dans les ovaires de souris durant la prophase méiotique. Nous avons utilisé une souche de souris mutantes pour la gene Msh5, dans lequelles tous les oocytes sont éliminés durant la vie néonatale. Msh5 code pour une protéine nécessaire à la synapse de chromosomes méiotiques.
Des souris hétérozygote Msh5 ont été croisées et les ovaires ont été isolées de la progéniture féminine de 14,5 à 22,5 dpc. Nous avons étudié la perte de cellules germinales dans les ovaires des femelles Msh5 -/- (MT) en les comparant à ceux des femelles Msh5 +/+ (WT) et Msh5 +/- (HT) par immunodétection en utilisant des anticorps anti-GCNA1 et anti-MVH (marqueurs des cellules germinales) ou par le comptage des cellules positives au GCNA1 dans des suspensions cellulaires. Nos résultats montrent une perte continue de cellules positives au GCNA1 chez les souris MT et WT, bien que la perte chez les MT a été constamment supérieure à celle des WT (différence significative à 19.5 dpc).
La progression de la méiose a été étudiée par immunodétection double pour GCNA1 et SC (complexe synaptonémal) ou pour SC et γH2AX sur des préparations de chromosomes. Nous avons constaté que la méiose chez les souris MT est bloquée dans le stage de transition zygotène-pachytène. Nous n'avons pas observé de pachytène normal chez les souris MT.
Le rôle de l'apoptose dans l'élimination d'oocytes au cours de la prophase méiotique a été étudié par analyse du clivage de diverses caspases (caspases 2, 3, 6, 7, 9) ainsi que celui de la PARP1 par immunobuvardage des protéines d'ovaires entières lysées. L'activation de la caspase 9 initiatrice a augmenté entre 17.5dpc et 18.5 dpc et a ensuite baissé à 19.5 dpc. Celle de la caspase 2L a augmenté d'une manière semblable, mais à des niveaux beaucoup plus bas. L'activation des caspases effectrice 3 et 6 est demeurée à des niveaux faibles mais celle de la caspase 7 bien que faible a augmenté légèrement à 19.5 dpc. Le clivage de PARP1 était élevé dans tous les stages. Dans tous ces cas, il n'y a pas eu de grandes différences dans le niveau moyen d'activation entre WT et MT. Par immunodétection de sections d'ovaires, nous avons observé que les caspases et PARP1 clivées étaient localisées dans des oocytes, mais aussi dans les cellules sans marquage pour GCNA1.
Ces résultats indiquent que la voie mitochondriale de l'apoptose peut jouer un rôle dans l'élimination d'oocytes au cours de la prophase méiotique, puisque les clivages de la caspase 9 et de PARP1 y sont associés. Cependant des études supplémentaires sont nécessaires pour l'identification de caspases effectrices.

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Loh, Benjamin Jia Hui. "Novel screens to identify genes regulating global chromatin structure during female meiotic prophase." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4613.

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During female meiotic prophase in many organisms, a specialized chromatin structure is formed in the oocyte nucleus. This structure is known as the karyosome, and has been proposed to be important for the formation of the female meiotic bipolar spindle. However, how the karyosome is formed and maintained is not very well understood. To identify proteins involved in the formation and maintenance of the karyosome, I carried out a cytological screen on a collection of 220 mutant fly lines for mutants that were defective in karyosome morphology. The screen identified 46 mutants on the X and 2nd chromosome with abnormal karyosomes. Genetic analysis of these 46 mutants, followed by molecular analysis of one mutant, identified SRPK (SR Protein Kinase) as a protein that is important for the proper formation of the karyosome. NHK-1 (Nucleosomal Histone Kinase 1) was previously identified as a protein that is essential for the formation of the karyosome via its phosphorylation of BAF (Barrier-to-Autointegration Factor). NHK-1 phosphorylation of BAF leads to the release of chromatin from the nuclear membrane, an essential step for the formation of the karyosome, however, the regulation of this process is unclear. In order to identify genes that interact with NHK-1, I carried out a genetic modifier screen using a semi-lethal allele of NHK-1, NHK-1trip. After screening a collection of 44 deficiencies located on the 2nd chromosome, I identified a genetic region (44B8-44D1) containing a gene that interacts with NHK-1 and, when gene dosage is halved, enhanced the semi-lethal phenotype of NHK-1trip.

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Hanafi, Jasmin. "Identifying factors involved in chromosome movement during prophase I of meiosis in Caenorhabditis elegans." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121248.

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Meiosis is a reductional cell division that produces haploid gametes and uniquely allows the introduction of genetic diversity via crossover recombination between homologous chromosomes. Any defect during this process could lead to the non disjunction of chromosomes, which in turn leads to aneuploidy in the resulting progeny, a condition that is generally lethal but in certain cases results in serious developmental abnormality. In C. elegans, at the onset of meiosis, chromosomes condense and cis-acting regions near each chromosome end called pairing centers recruit zinc-finger proteins which help chromosomes associate with nuclear envelope bridge proteins. These bridge proteins are in turn linked to the cytoskeleton network. This association is important to facilitate chromosome clustering and homology search. Once chromosomes are properly homologously paired, the process of division continues until eventually four haploid cells are produced. Though the successful coordination and regulation of each step in meiosis is critical for the survival of a species, many components of the process remain unclear. During prophase I, chromosome movement resulting in proper homologous pairing is controlled and regulated in a manner that is not well understood. The objective of my research therefore, is to try and identify factors involved in this chromosome movement. To do this, a candidate RNAi screen of 482 genes was conducted and 156 genes were positively identified as having a lack of chromosome movement. Since any mistakes in pairing and subsequent stabilization of homologous chromosomes could lead to non disjunction and possible embryonic lethality (emb) from loss of an autosome or a high incidence of males (him) from loss of the X chromosome, positive candidates were also screened for emb and him. Of the 156 positive candidates, 24 were also positive for emb and 1 was additionally positive for him. These candidates present many possibilities for further validation and characterization in future projects.
La méiose est une division cellulaire réductionnelle qui produit des gamètes haploïdes et permet d'une façon unique l'introduction de diversité génétique à travers la recombinaison entre les chromosomes homologues. Tout problème dans le processus peut causer une impossibilité de séparation entre les chromosomes, ce qui à son tour cause l'aneuploïdie dans la génération suivante, une condition qui est généralement mortelle, mais résulte en anomalie dans le développement dans certains cas. Les chromosomes de C. elegans, au tout début de la méiose, se condensent et les régions "cis" à la fin de chaque chromosome appelées centres paires recrutent les protéines avec des doigts de zinc qui aident les chromosomes associer avec le pont de protéines sur l'enveloppe nucléaire. Le pont est connecté au réseau cytosquelette. Cette association est importante pour la facilitation du regroupement des chromosomes et la recherche de chromosomes homologues. À la retrouvaille des chromosomes homologues, le processus de division continue jusqu'à ce que quatre cellules haploïdes soient produites. Même si le succès de la coordination de chaque étape de la méiose est critique pour la survie des espèces, certain détails du processus restent inconnus.Durant la prophase I, le mouvement des chromosomes qui résulte dans le propre couplement des chromosomes homologues est contrôlé et régulé d'une manière encore inconnue. L'objectif de mes recherches est donc d'identifier des facteurs associés dans ledit mouvement des chromosomes. Pour accomplir ce but un écran de ARNi avec 482 gènes comme candidates a été mené et 156 gènes ont été positivement identifiés pour une manque de mouvement des chromosomes. Comme tout problème de formation des couples de chromosomes ainsi que dans la stabilisation des chromosomes homologues qui suit peut causer de la non-disjonction et possible mort embryonnaire (emb) suite à la perte d'un autosome ou une haute incidence de males (him) causé par la perte du chromosome X, les candidats out aussi été examinés pour emb et him. Des 156 candidats positifs, 24 ont aussi été positifs pour emb et un candidat a été additionnellement positif pour him. Ces candidats se présentent comme une source de futures recherches de validation ainsi que de caractérisation.

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Guichaoua, Marie-Roberte. "L'infertilité masculine d'origine chromosomique : ses mécanismes : apport de l'étude du stade pachytène dans les spermatocytes I en prophase de Méiose." Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX21904.

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Pyatnitskaya, Alexandra. "Interplay between meiotic crossing-overs and chromosome architecture : role of the meiosis specific complex Zip2-Zip4-Spo16." Electronic Thesis or Diss., Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLS061.

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La méiose est une étape essentielle de la reproduction chez tous les organismes sexués. En effet, celle-ci permet l’obtention de quatre gamètes haploïdes à partir d’une seule cellule diploïde grâce à la réalisation deux divisions successives suivant une seule étape de réplication. Un des éléments essentiels permettant une bonne ségrégation en première division méiotique est la création d’un échange physique entre les chromosomes homologues parentaux. Ce lien physique, plus communément appelé crossing-over (CO), est produit par un mécanisme de recombinaison entre les chromosomes homologues au cours de la prophase I méiotique. La recombinaison homologue est initiée par la formation simultanée de nombreuses cassures double-brin au sein du génome. Chez la levure de boulanger, la formation des COs est dépendante de la famille protéique ZMM (un acronyme pour Zip1/2/3/4-Msh4/5-Mer3-Spo16) composée de huit protéines hautement conservées, et impliquées dans la reconnaissance et la stabilisation des intermédiaires d’ADN formés au cours de la recombinaison homologue. Nous avons montré que la protéine Zip4 forme un complexe stable avec deux autres protéines ZMM, Zip2 et Spo16. Le complexe Zip2-Zip4-Spo16 (ZZS), de type XPF-ERCC1, serait capable de reconnaitre et de stabiliser les intermédiaires de recombinaison afin de promouvoir leur réparation en tant que CO. Chez les mammifères, Zip2 et Zip4 possèdent des homologues décrits, SHOC1 et TEX11 respectivement, mais aucun homologue n’a été découvert pour Spo16. Nous avons réalisé une analyse in silico et pu déterminer un homologue de Spo16 chez les mammifères, MmSPO16. Par la suite, j’ai pu co-purifier MmSPO16 avec le domaine XPF de SHOC1, ce qui suggère la conservation du complexe ZZS chez les mammifères. De plus, le processus de formation des COs est corrélé́ à la mise en place d’un complexe protéique formé entre les deux chromosomes homologues, appelé complexe synaptonémal (CS). Le CS est composé de deux éléments axiaux, accolés entre eux à une distance précise de 100 nm par la région centrale. La région centrale comprend un élément central, composé de l’hétérodimère Ecm11-Gmc2, et d’un élément transversal formé par la protéine Zip1. Les éléments transversaux partant des axes opposés se lient tête-bêche au niveau de l’élément central. Malgré des liens fonctionnels évidents entre la formation des COs et l’assemblage du CS entre les chromosomes homologues, aucun lien physique direct n’a été établi à ce jour. Au cours de mon doctorat, j’ai pu démontrer l’existence d’une interaction physique entre la protéine du CS Ecm11 et la protéine ZMM Zip4. Cette interaction est nécessaire pour la localisation et la polymérisation d’Ecm11 sur les chromosomes, l’assemblage correct du CS et la ségrégation des chromosomes homologues en première division méiotique
Meiosis is a highly conserved mechanism among organisms with sexual development. This process consists in producing four haploid gametes from one diploid cell by executing two successive rounds of cell division. During the first meiotic division, reciprocal exchanges of parental DNA strands, also known as crossing-overs (COs), ensure the faithful segregation of homologous chromosomes. COs arise from a specific type of DNA repair, homologous recombination. This pathway is initiated by the simultaneous induction of hundreds of double strand breaks (DSBs) in the genome. In budding yeast, the major CO pathway is promoted by a family of eight conserved proteins, named ZMMs (acronym for Zip1/2/3/4-Msh4/5-Mer3-Spo16), involved in recognizing and stabilizing DNA intermediates formed during homologous recombination. We showed that the Zip4 protein forms a stable tripartite complex with two other ZMM proteins, Zip2 and Spo16. Our data suggests that the Zip2-Zip4-Spo16 (ZZS) complex binds recombination intermediates through its XPF-ERCC1-like domain and drives them towards a CO fate. The homologs of Zip2 and Zip4 in mammals, SHOC1 and TEX11 respectively, have been described, but no Spo16 homolog has been found so far. We could identify the homolog of Spo16 in mammals by an in silico screen, MmSPO16. In addition, I could co-purify MmSPO16 with the XPF domain of SHOC1, thus revealing the potential conservation of the entire ZZS complex in mammals. ZMM-dependent COs are formed within the context of a meiosis-specific structure, named synaptonemal complex (SC). The SC is a proteinaceous structure composed of two axial elements physically maintained together at a precise distance of 100 nm by a central region. The central region encompasses a central element, composed of the two proteins Ecm11 and Gmc2, and the transverse filaments composed of Zip1. The transverse filaments from opposing axial elements overlap and bind head-to-head in the central element. However, despite evidence of a close relationship between SC assembly and CO formation, nothing is known about a direct link that could coordinate these two events spatially and temporally. During my PhD, I found a new interaction between the SC protein Ecm11 and the ZMM protein Zip4. This newly discovered interaction is necessary for Ecm11 association and polymerization on chromosomes, the SC assembly and the homolog disjunction in meiosis I. Our results suggest a direct connection that ensures SC assembly from CO sites through the Zip4-Ecm11 interaction. This way, ensuring SC polymerization from emerging CO sites could be a way of fine-tuning CO distribution, by participating to CO interference and/or by regulating nearby DSB formation. Moreover, I could identify an interaction between the mammalian ortholog of Zip4, TEX11, and one of the five members composing the SC central element, TEX12, raising the possibility that this mechanism synchronizing CO formation and SC polymerization could be conserved

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Books on the topic "Prophase I"

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Prophesy! London: Triangle, 1998.

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Kahlil, Gibran. Le prophète. Paris: Guy Trédaniel, 1999.

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Gibran, Kahlil. Le prophète. Boucherville, Québec: Éditions de Mortagne, 1992.

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Kahlil, Gibran. Le Prophète. Paris: EJL, 2003.

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Kahlil, Gibran. Le Prophète. [Place of publication not identified]: FMA, 1995.

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Marguerite, prophète: Roman. Montréal]: Carte blanche, 2014.

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Le prophète Osée. Lausanne: Georges Bridel, 1985.

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Truth seer prophesy. Milton Keynes: AuthorHouse, 2008.

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Seddik, Youssef. Dits du prophète. [Paris?]: Sindbad, 1997.

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Malenfant, Fernand. Le prophète amoureux. Cap-Saint-Ignace, Québec: La Plume d'oie, 1999.

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Book chapters on the topic "Prophase I"

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Bährle-Rapp, Marina. "Prophase." In Springer Lexikon Kosmetik und Körperpflege, 454. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_8528.

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Mana-Capelli, Sebastian, and Dannel McCollum. "Pre-Prophase Band." In Encyclopedia of Systems Biology, 1736–37. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-9863-7_782.

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Scherthan, H. "Chromosome behaviour in earliest meiotic prophase." In Chromosomes Today, 217–48. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1537-4_14.

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Roig, Ignasi, and Montserrat Garcia-Caldés. "Cytological Techniques to Study Human Female Meiotic Prophase." In Methods in Molecular Biology, 419–31. Totowa, NJ: Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60761-103-5_24.

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Rodriguez-Garcia, M. I., J. D. Alché, A. Majewska-Sawka, M. C. Fernandez, and B. Jassem. "Nuclear Compartmentalization in Pollen Mother Cells During Meiotic Prophase." In Nuclear Structure and Function, 493–97. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0667-2_101.

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Reichman, Rachel, Benjamin Alleva, and Sarit Smolikove. "Prophase I: Preparing Chromosomes for Segregation in the Developing Oocyte." In Results and Problems in Cell Differentiation, 125–73. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44820-6_5.

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Arur, Swathi. "Signaling-Mediated Regulation of Meiotic Prophase I and Transition During Oogenesis." In Results and Problems in Cell Differentiation, 101–23. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44820-6_4.

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Jaffe, Laurinda A., and Rachael P. Norris. "Initiation of the Meiotic Prophase-to-Metaphase Transition in Mammalian Oocytes." In Oogenesis, 179–97. Chichester, UK: John Wiley & Sons, Ltd, 2010. http://dx.doi.org/10.1002/9780470687970.ch7.

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Fu-zhou, Luo, and Wang La-Yin. "Study on Prophase Risk Management in Informatization of Chinese Construction Enterprises." In Computational Risk Management, 81–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15243-6_10.

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Cau, Julien, Laurine Dal Toe, Akbar Zainu, Frédéric Baudat, and Thomas Robert. "“MeiQuant”: An Integrated Tool for Analyzing Meiotic Prophase I Spread Images." In Methods in Molecular Biology, 263–85. New York, NY: Springer US, 2024. http://dx.doi.org/10.1007/978-1-0716-3698-5_17.

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Conference papers on the topic "Prophase I"

1

Zheng, Liu, Sun Shouqian, and Pan Yunhe. "Information framework in product design prophase analysis." In 2006 7th International Conference on Computer-Aided Industrial Design and Conceptual Design. IEEE, 2006. http://dx.doi.org/10.1109/caidcd.2006.329356.

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Saravanan, N. P., R. Gokul, B. Akshykumar Bhiva Mote, and K. Hariprakash. "Early Prophase of Alzheimer Disease Using Deep Learning." In 2022 International Conference on Computer Communication and Informatics (ICCCI). IEEE, 2022. http://dx.doi.org/10.1109/iccci54379.2022.9740766.

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"3D-microscopy of prophase nucleus in the meiosis I of wheat-rye amphihaploids." In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 2019. http://dx.doi.org/10.18699/plantgen2019-106.

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Lei, Yu, Ruyu Zhang, Yan Ding, Jianfeng Lin, Lirong Liu, and Lei Qin. "The Schedule Optimization and Control of Nuclear Power Construction Project Prophase Based on Petri Network." In 2015 6th International Conference on Manufacturing Science and Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/icmse-15.2015.48.

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Hong, Ke, Song Zhenhua, and Li Juan. "Research on the Application of the Virtual United Organization in the Prophase of the Construction Project." In 2010 International Conference on E-Business and E-Government (ICEE). IEEE, 2010. http://dx.doi.org/10.1109/icee.2010.701.

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Qin, Yuan, Xinfeng Zhang, Houcheng Zhang, Wenhao Li, Ye Lin, and Han Yue. "A Prophase Simulation Study of Fuel Cell-Battery Hybrid System for eVTOL Aircraft in Steady-State Operation." In SAE 2023 Intelligent Urban Air Mobility Symposium. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-7092.

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<div class="section abstract"><div class="htmlview paragraph">Electric vertical take-off and landing (eVTOL) is defined as vertical lift aircraft propelled by electric power and capable of carrying people. Based on the system of battery powered CY300 eVTOL, a fuel cell-battery hybrid system (FBHS) in steady-state operation as a potential propulsion system for CY300 eVTOL is proposed. In order to analyze the feasibility of FBHS-powered eVTOL system, a mathematical model is established to evaluate the proposed system performance considering various irreversible effects. Furthermore, considerable sensitivity analyses indicate that the payload of the proposed system is considerably benefited by a higher specific energy of the battery system, specific power of the fuel cell system and hydrogen storage ratio of the hydrogen tank. Hydrogen tank weight decreases the payload while enhances the hovering time. DoH accounts for power balancing between two power sources, and affects the impacts of different design parameters on the performance of the proposed FBHS. In order to achieve a long endurance eVTOL with a cruise time of more than 30 min and a payload rate of more than 30%, the specific energy of the battery system in this proposed FBHS needs to be greater than 500 Wh/kg, and the specific power of the fuel cell system needs to reach more than 1000 W/kg. For hydrogen storage technology selections, high pressure gaseous hydrogen storage technologies are suitable enough for short-range eVTOLs, but liquid hydrogen powered eVTOLs can be an ideal solution for long-endurance aircraft. The results acquired may be helpful in designing and optimizing such an actual power system.</div></div>

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MA, JU, and V. V. KHROMYKH. "ANALYSIS OF TEMPORAL AND SPATIAL CHANGE OF LAND USE IN LAOS BASED ON GEOINFORMATION TUPU." In Теоретические и прикладные проблемы ландшафтной географии. VII Мильковские чтения. Voronezh State University, 2023. http://dx.doi.org/10.17308/978-5-9273-3692-0-2023-227-230.

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Based on the land use raster data of Laos in 2000, 2010, and 2020, using technologies such as geoscience information atlas and GIS spatial analysis, two-time series maps of land use change and land use change patterns were constructed to explore the land use changes in Laos from 2000 to 2020. Spatial and temporal changes in land use and development processes. The results show that the change map of main land use types in Laos from 2000 to 2020 is dominated by the conversion of Forest to Cultivated land and runs through the entire study period, but there are some differences in the changes of land use types among the provinces of Laos; in the map of change patterns, the No change pattern occupies the Main position, followed by Prophase change mode, Anaphase change mode, and Repeated change, and Continuous change accounted for the least.

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"Order of chromosome arrangement location in late prophase – early prometaphase of mitosis in haploid maize plant obtained with the use of mutation ig." In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Novosibirsk ICG SB RAS 2021, 2021. http://dx.doi.org/10.18699/plantgen2021-219.

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Williams, Kelly. "Precise prophage mapping." In Proposed for presentation at the Viruses of Microbes held July 18-22, 2022 in Guimaraes, Portugal. US DOE, 2022. http://dx.doi.org/10.2172/2003938.

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Williams, Kelly. "Discovery Through Precise Prophage Mapping." In Proposed for presentation at the Phages for Health and Energy held September 23-24, 2021 in Livermore, CA. US DOE, 2021. http://dx.doi.org/10.2172/1889352.

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