Prophase I arrest and progression to metaphase I in mouse oocytes are controlled by Emi1-dependent regulation of APCCdh1

Mammalian oocytes are arrested in prophase of the first meiotic division. Progression into the first meiotic division is driven by an increase in the activity of maturation-promoting factor (MPF). In mouse oocytes, we find that early mitotic inhibitor 1 (Emi1), an inhibitor of the anaphase-promoting complex (APC) that is responsible for cyclin B destruction and inactivation of MPF, is present at prophase I and undergoes Skp1–Cul1–F-box/βTrCP-mediated destruction immediately after germinal vesicle breakdown (GVBD). Exogenous Emi1 or the inhibition of Emi1 destruction in prophase-arrested oocytes leads to a stabilization of cyclin B1–GFP that is sufficient to trigger GVBD. In contrast, the depletion of Emi1 using morpholino oligonucleotides increases cyclin B1–GFP destruction, resulting in an attenuation of MPF activation and a delay of entry into the first meiotic division. Finally, we show that Emi1-dependent effects on meiosis I require the presence of Cdh1. These observations reveal a novel mechanism for the control of entry into the first meiotic division: an Emi1-dependent inhibition of APCCdh1

Dual-mode regulation of the APC/C by CDK1 and MAPK controls meiosis I progression and fidelity

Dernière mise à jour : 26 août 2015 Il existe plusieurs enregistrements de cette chanson gaillarde de Saint-Gelais, notamment mise en musique par Pierre Certon et Clément Janequin. Parmi ceux-ci, Jacques Feuillie Vocal Group, Libertine songs of the French Renaissance, 1975. Le verger de musique, Antony Auvidis, 1999 (1996). Joël Cohen and The Boston Camerata, Pierre Certon : chansons, Harmonia Mundi, 2008 (1980). Württembergischer Kammerchor, Kurz Dieter, Trink- und Liebeslieder der Renaissa..

Scientific Report 2011-2012

144 p.-MEMORIA DE LA DIRECCION: El Centro de Investigaciones Biológicas (CIB) es uno de los centros de investigación con mayor prestigio y tradición en la Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC). El CIB ha estado en la vanguardia de la investigación en Biología desde su creación en 1953. La actividad inicial del CIB estuvo fundamentalmente orientada hacia estudios en Biología y Biomedicina pero actualmente es un Centro multidisciplinar, que agrupa de la Dirección | Director’s Report investigadores de las áreas de Biología, Ciencias Agrarias y Químicas. Es un Centro activo y dinámico, en constante evolución. Durante su larga trayectoria, el CIB ha formado grandes investigadores que han sido la semilla de otros centros de prestigio como el Centro de Biología Molecular Severo Ochoa, el Instituto Cajal y el Instituto de Investigaciones Biomédicas Alberto Sols en Madrid, el Instituto de Bioquímica Vegetal y Fotosíntesis en Sevilla y el de Instituto de Microbiología Bioquímica en Salamanca (actualmente Instituto de Biología Funcional y Genómica). En la actualidad el CIB acoge alrededor de 560 profesionales incluyendo investigadores de plantilla, doctores contratados, becarios y contratados realizando su Tesis Doctoral y otros profesionales dedicados a la administración y mantenimiento del Centro. Su ubicación actual, en el Campus de Moncloa, rodeado de las Facultades de Biología, Física, Química, Farmacia y Medicina y las Escuelas de Forestales y Agrónomos, nos sitúa en un marco inigualable para establecer colaboraciones con el ámbito universitario, participando en cursos de Grado y de Máster para la formación de jóvenes científicos. Además, el CIB colabora con diferentes Escuelas para la formación de técnicos cualificados. El carácter multidisciplinar del CIB lo convierte en una referencia para la formación de nuevos científicos y técnicos, perfectamente capacitados para su integración en los laboratorios de las mejores instituciones internacionales y empresas. La financiación necesaria para las investigaciones realizadas en nuestro Centro se obtiene de diferentes agencias, tanto internacionales como nacionales, mediante concursos competitivos, así como de contratos con empresas. El CIB lleva a cabo además un importante papel en la transferencia de conocimiento, poniendo a disposición de la sociedad los resultados de la investigación científica mediante la generación de patentes, que recogen los logros del CIB en diferentes campos como el diseño de nuevos abordajes terapéuticos, vacunas, ensayos biológicos o procedimientos para el desarrollo biotecnológico o industrial. Además, en el CIB se han creado dos empresas de base tecnológica (spin-off) para potenciar el desarrollo tecnológico de estas investigaciones. Todas estas líneas de actuación se encuadran en cinco grandes programas de investigación organizados en torno a cinco Departamentos:• Biología Ambiental. Estudia como los seres vivos interaccionan con el medio ambiente que les rodea, incluyendo la relación de las plantas con el medio biótico y abiótico, nuevas estrategias para el control de plagas o la utilización de microorganismos y sus enzimas para el desarrollo sostenible de aplicaciones industriales y medioambientales. • Biología Celular y Molecular. Estudia dos aspectos diferentes y complementarios de los procesos de identidad y regulación celular en procariotas y eucariotas: i) bases moleculares de la unidad celular y su integración en tejidos y órganos y ii) aproximaciones sintéticas “bottom-up” para el diseño y microfabricación de componentes que permitan nuevas funcionalidades de las células. • Biología Físico-Química. Trata de entender problemas biológicos específicos, a distintos niveles de complejidad, a través de la química y la física de las proteínas y otras moléculas biológicas, con el fin de predecir funciones esenciales y poder proponer aplicaciones biomédicas y/o biotecnológicas. • Medicina Celular y Molecular. Su objetivo es comprender las bases moleculares de diferentes patologías humanas, enfermedades raras o comunes con gran repercusión en la sociedad, para desarrollar estrategias que ayuden a diseñar nuevas terapias combinando estudios genéticos, celulares y estructurales. • Microbiología Molecular yBiología de la Infección. Se ocupa de una manera singular de desarrollar estrategias originales para el tratamiento de enfermedades producidas por microorganismos, tras conocer los mecanismos moleculares que controlan estas infecciones. Por otro lado, es preciso destacar que el CIB está dotado de un gran número de Servicios Científicos especializados (animalario, citometría de flujo, cromatografía de gases, microscopía electrónica y confocal, secuenciación de ADN y péptidos, proteómica y genómica, resonancia magnética nuclear de biomoléculas, síntesis de péptidos u oligonucleótidos y ultracentrifugación analítica), con personal altamente cualificado, que además de prestar apoyo a los investigadores de este Centro y del CSIC, dan cobertura a otros Centros de Investigación (públicos o privados), Universidades y empresas. También contamos con una excelente biblioteca, que cuenta con uno de los fondos bibliográficos más importantes de Europa en el ámbito de la Biología y Biomedicina, y con una red de servicios de apoyo a la investigación que incluye administración, gerencia, cultivos celulares, esterilización, informática, protección radiológica y la unidad de servicios técnicos e infraestructuras. Finalmente, comentar que la multidisciplinaridad es uno de los grandes valores de nuestro Centro, permitiendo la integración de metodologías y aproximaciones experimentales distintas, en un momento en el que se hace evidente que, dada su complejidad, los procesos biológicos solo se pueden comprender mediante aproximaciones distintas y complementarias. Pero este valor se convierte en un reto en las actuales circunstancias, puesto que mantener la competitividad en áreas técnicas y científicas muy diversas exige una adaptación constante a los avances tecnológicos y una renovación y modernización continua de los grandes equipos. A pesar de la difícil situación actual, con una reducción de fondos importantes, el CIB cuenta con un gran número de profesionales expertos en áreas muy diversas, que apuestan por afrontar juntos los retos actuales y futuros para seguir siendo un centro de referencia nacional e internacional.DIRECTOR'S REPORT: The Biological Research Centre (CIB) is one of the most prestigious research centres of the Spanish National Research Council (CSIC), and has been at the forefront of biological research since its creation in 1953. The initial activity of the CIB focused primarily on studies in the fields of biology and biomedicine, but currently the CIB is a multidisciplinary centre, bringing together researchers in the areas of biology, agricultural sciences and chemistry. It is an active, dynamic centre in constant evolution. During its long history, the CIB has trained and supported outstanding researchers who have been the driving force behind the formation of other top centres such as the Severo Ochoa Molecular Biology Centre, the Cajal Institute, and the Alberto Sols Molecular Biology Centre in Madrid, the Institute of Biology and Photosynthesis in Seville, and the Institute of Microbiology and Biochemistry in Salamanca. At present, the CIB is constituted by approximately 560 professionals including staff researchers, contract researchers, scholarship and PhD students, as well as administrative and maintenance personnel. The CIB is currently located within the campus of Madrid’s Complutense and Politécnica Universities, surrounded by the Faculties of Biology, Physics, Chemistry, Pharmacy and Medicine, as well as the Schools of Forestry and Agronomy. This places it in a unique setting for collaboration with academic researchers, participating in undergraduate and graduate courses and in the training of young scientists and qualified technicians. The multidisciplinary character of the CIB has made it a recognised centre for the training of new scientists and technicians qualified for inclusion in high caliber academic and industrial laboratories. Funding for research conducted at CIB is obtained from different agencies, both national and international, through competitive funding programs and contracts with companies. Furthermore, the CIB carries out an important role in knowledge and technology transfer, making available to the society the scientific results through the generation of patents that reflect CIB achievements in different fields, such as the design of new therapeutic approaches, vaccines, biological tests or procedures for biotechnological or industrial development. Moreover, CIB has created two technology-based spin-off companies to foster the technological development of this research. All these studies are part of five major research programmes organised around five departments:• Environmental Biology. It focuses in the understanding on how living organisms interact and respond to the environment, including studies on plants and their abiotic and biotic milieu, management of insect pest populations or the use of microorganisms and their enzymes for the sustainable development of industrial and environmental applications. • Cellular and Molecular Biology. It investigates two different and complementary aspects concerning the identity and regulation of prokaryotic or eukaryotic cells: i) Molecular basis of cell development and its integration in specialized cell types, tissues and organs and ii) synthetic approximations “bottom-up” for the design and micro-production of new cell components with new functionality. • Chemical and Physical Biology. Its main research goal is to develop a quantitative understanding of specific biological problems at different levels of complexity through the physics and chemistry of proteins and other biological molecules, to predict essential biological functions and to design biomedical and/or biotechnological applications. • Cellular and Molecular Medicine. Its goal is to understand the molecular mechanisms involved in human physiopathology, rare or common illnesses with high social impact, to develop strategies to design new therapies on the basis of genetic, cellular and structural studies. • Molecular Microbiology and Infection Biology. It studies the characterization of the molecular processes that control the life cycle and functions of microorganisms, as well as the molecular mechanisms involved in the regulation of microorganism-host interactions. The CIB is equipped with a large number of specialized scientific services (animal facility, flow cytometry, gas chromatography, electronic and confocal microscopy, DNA and peptide sequencing, proteomics, nuclear magnetic resonance of biomolecules, peptide or oligonucleotide synthesis and analytical ultracentrifugation) with highly qualified personnel, that besides helping researchers of this centre and the CSIC are also available to other research centres (public or private) universities, and companies. We can also count on an excellent library, with one of the most important bibliographical collections in Europe in the area of cellular biology and biomedicine, together with a network of research support services that includes administration, management, cellular cultures, sterilization, computer science and radiological protection along with the technical service and infrastructure unit. The multi-disciplinary character of our centre is one of its great assets, facilitating the integration of different methodologies and experimental approaches at a time when it has become clear that, given their complexity, biological processes can only be understood through such distinct complementary approaches. However, under present circumstances this asset has become a challenge, since maintaining competitiveness in very diverse technical and scientific areas requires a constant adaptation to new technological advances and a continual renewal and update of highly sophisticated instrumentation. Despite the difficult current situation, with important reductions in funding, the CIB can count on a large number of professionals who are experts in very diverse fields, who are committed to facing the present and future challenges together so that the CIB can continue to be an important reference centre both nationally and internationally.Peer reviewe

Cyclin A2 modulates kinetochore–microtubule attachment in meiosis II

Cyclin A2 is a crucial mitotic Cdk regulatory partner that coordinates entry into mitosis and is then destroyed in prometaphase within minutes of nuclear envelope breakdown. The role of cyclin A2 in female meiosis and its dynamics during the transition from meiosis I (MI) to meiosis II (MII) remain unclear. We found that cyclin A2 decreases in prometaphase I but recovers after the first meiotic division and persists, uniquely for metaphase, in MII-arrested oocytes. Conditional deletion of cyclin A2 from mouse oocytes has no discernible effect on MI but leads to disrupted MII spindles and increased merotelic attachments. On stimulation of exit from MII, there is a dramatic increase in lagging chromosomes and an inhibition of cytokinesis. These defects are associated with an increase in microtubule stability in MII spindles, suggesting that cyclin A2 mediates the fidelity of MII by maintaining microtubule dynamics during the rapid formation of the MII spindle

Regulation of the meiotic cell cycle in mouse oocytes

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The regulation of meiosis in mouse oocytes

The overall aim of the experiments presented in this thesis is to investigate the regulation of meiosis in mammalian oocytes. To investigate the role of cyclin B during progression through meiosis I to II we have made use of a cyclin B1-GFP fusion protein. Injection of cyclin B1-GFP accelerates GVBD and overrides cAMP-mediated arrest at the GV stage. Excess cyclin B can accelerate or inhibit the extrusion of PB1 in a dose-dependent manner. The distribution of cyclin B1-GFP was found to be controlled through the regulation of nuclear import and export. Within 15 minutes of GVBD, cyclin B1- GFP accumulates in the GV, presumably due to a rise in import and a decrease in export. Cyclin BL-GFP is also a tool for examining cyclin degradation that is necessary for exit from M-phase. In MI we find cyclin B destruction is necessary for progression through MI. Cyclin B destruction at Mil is stimulated by an increase in Ca2+ at fertilisation. This destruction results in an increase in the rate of cyclin B degradation. Producing Ca2+ transients during MI does not induce cyclin B degradation showing cyclin B destruction becomes sensitive to Ca2+ late in meiosis. Furthermore, we examined the role of Emil in meiosis. Emil is present in both MI and MIL By microinjecting Emil protein we found that Emil blocks polar body extrusion. By injecting morpholinos aimed against the endogenous Emil mRNA, we managed to block the maturation of oocytes at prometaphase which implies a role for Emil in MI. Emil depletion also caused the release of MII eggs from metaphase arrest. This showed that this protein may be, as MAPK, a component of the cytostatic factor, which is responsible for the arrest at MII. Finally, we examined the relationship of Ca2+ oscillations and cell cycle resumption at fertilisation. Ca2+ oscillations do not depend on normal levels of CDKl-cyclin B since they continue after CDKl activity has declined. Moreover, they are not sensitive to the MAPK inhibitor, U0126. The data demonstrate a strong correlation between Ca2+ oscillations and Pn formation. In this thesis we present a model whereby Ca2+ oscillations at fertilisation and mitosis are controlled by the nuclear sequestration of a sperm-derived Ca2+-releasing factor, such as PLCζ

Cell Cycle-dependent Regulation of Structure of Endoplasmic Reticulum and Inositol 1,4,5-Trisphosphate-induced Ca(2+) Release in Mouse Oocytes and Embryos

The organization of endoplasmic reticulum (ER) was examined in mouse eggs undergoing fertilization and in embryos during the first cell cycle. The ER in meiosis II (MII)-arrested mouse eggs is characterized by accumulations (clusters) that are restricted to the cortex of the vegetal hemisphere of the egg. Monitoring ER structure with DiI18 after egg activation has demonstrated that ER clusters disappear at the completion of meiosis II. The ER clusters can be maintained by inhibiting the decrease in cdk1-cyclin B activity by using the proteasome inhibitor MG132, or by microinjecting excess cyclin B. A role for cdk1-cyclin B in ER organization is further suggested by the finding that the cdk inhibitor roscovitine causes the loss of ER clusters in MII eggs. Cortical clusters are specific to meiosis as they do not return in the first mitotic division; rather, the ER aggregates around the mitotic spindle. Inositol 1,4,5-trisphosphate-induced Ca(2+) release is also regulated in a cell cycle-dependent manner where it is increased in MII and in the first mitosis. The cell cycle dependent effects on ER structure and inositol 1,4,5-trisphosphate-induced Ca(2+) release have implications for understanding meiotic and mitotic control of ER structure and inheritance, and of the mechanisms regulating mitotic Ca(2+) signaling

The DNA Damage Response in Fully Grown Mammalian Oocytes

DNA damage in cells can occur physiologically or may be induced by exogenous factors. Genotoxic damage may cause cancer, ageing, serious developmental diseases and anomalies. If the damage occurs in the germline, it can potentially lead to infertility or chromosomal and genetic aberrations in the developing embryo. Mammalian oocytes, the female germ cells, are produced before birth, remaining arrested at the prophase stage of meiosis over a long period of time. During this extensive state of arrest the oocyte may be exposed to different DNA-damaging insults for months, years or even decades. Therefore, it is of great importance to understand how these cells respond to DNA damage. In this review, we summarize the most recent developments in the understanding of the DNA damage response mechanisms that function in fully grown mammalian oocytes