DOCSLIB.ORG

Initiation of DNA Replication After Fertilization Is Regulated by P90rsk at Pre-RC/Pre-IC Transition in Starfish Eggs

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Initiation of DNA Replication After Fertilization Is Regulated by P90rsk at Pre-RC/Pre-IC Transition in Starfish Eggs Initiation of DNA replication after fertilization is regulated by p90Rsk at pre-RC/pre-IC transition in starfish eggs Kazunori Tachibana, Masashi Mori1, Takashi Matsuhira, Tomotake Karino, Takuro Inagaki, Ai Nagayama, Atsuya Nishiyama2, Masatoshi Hara, and Takeo Kishimoto3 Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Yokohama 226-8501, Japan Communicated by Joan Ruderman, Harvard Medical School, Boston, MA, January 17, 2010 (received for review August 31, 2009) Initiation of DNA replication in eukaryotic cells is controlled through ase, p90Rsk) pathway causes the G1-phase arrest at the pronu- an ordered assembly of protein complexes at replication origins. The cleus stage (6–10). Fertilization induces degradation of Mos to molecules involved in this process are well conserved but diversely shutdown this pathway, leading to the first S phase with no regulated. Typically, initiation of DNA replication is regulated in requirement of new protein synthesis. However, it remains response to developmental events in multicellular organisms. Here, unclear how p90Rsk negatively controls the G1/S-phase tran- we elucidate the regulation of the first S phase of the embryonic cell sition, or to which stage the initiation complex for DNA repli- cycle after fertilization. Unless fertilization occurs, the Mos-MAPK- cation is assembled in unfertilized G1-phase eggs. Here we show p90Rsk pathway causes the G1-phase arrest after completion of that the p90Rsk-dependent G1-phase arrest of unfertilized meiosis in starfish eggs. Fertilization shuts down this pathway, starfish eggs occurs at the pre-RC stage, and that in the absence leading to the first S phase with no requirement of new protein of Cdk1 and Cdk2 activities and Cdc7 accumulation, inactivation synthesis. However, how and in which stage the initiation complex of p90Rsk is necessary and sufficient for further loading of Cdc45 fi for DNA replication is arrested by p90Rsk remains unclear. We nd and the subsequent initiation of DNA replication. that in G1-arrested eggs, chromatin is loaded with the Mcm complex to form the prereplicative complex (pre-RC). Inactivation of p90Rsk Results fi is necessary and suf cient for further loading of Cdc45 onto Female Pronuclei in Unfertilized Eggs Are Licensed for DNA chromatin to form the preinitiation complex (pre-IC) and the Replication. We first determined the timing of S phase. A 5-min subsequent initiation of DNA replication. However, cyclin A-, B-, pulse incorporation of BrdU to DNA indicates that the first S and E-Cdk’s activity and Cdc7 accumulation are dispensable for ∼ ∼ fi phase begins 30 min and ends 45 min after insemination of these processes. These observations de ne the stage of G1 arrest eggs arrested at G1 phase (Fig. 1A and Fig. S1) (11). In parallel, in unfertilized eggs at transition point from pre-RC to pre-IC, and congression and fusion between female and male pronuclei reveal a unique role of p90Rsk for a negative regulator of this tran- occurred (12), while DNA replication appeared to start sepa- sition. Thus, initiation of DNA replication in the meiosis-to-mitosis rately and almost simultaneously in each pronucleus and then to transition is regulated at the pre-RC stage as like in the G1 check- continue for a little longer period in male pronuclei. Thereafter, point, but in a manner different from the checkpoint. M phase started at ∼60 min (Fig. 1A and Fig. S1). To investigate assembly of the initiation complex for DNA Cdc45 | G1 arrest | Mcm complex | Mos-MAPK pathway | oocyte-to-embryo transition replication before and after fertilization, we isolated cDNAs of starfish orthologs of Cdc6, Mcm2, Mcm7, and Cdc45 and raised antibodies to these proteins (Figs. S2 A–D and S3 A–D). All of NA replication in eukaryotic cells is initiated through an these proteins were detectable in unfertilized eggs, and their Dordered assembly of protein complexes at replication origins E fi protein levels remained constant during cleavage cycles (Fig. 1 (1, 2). Replication origins are rst recognized and bound by the for Cdc45 and Fig. S3H for Cdc6 and Mcm2). Both Cdc6 and origin recognition complex (ORC). During late M or early G1 Mcm2 were already detectable on chromatin of female pronuclei phase, Cdc6 associates onto ORC-containing DNA. Then, MCM in unfertilized eggs arrested at G1 phase (Fig. 1B and C; 0 min). (minichromosome maintenance) proteins associate with the After fertilization, they remained localized on chromatin at ORC- and Cdc6-containing replication origins, requiring Cdt1 to almost constant levels until S phase. As DNA replication pro- form a prereplicative complex (pre-RC). At the onset of S phase, gressed, the Mcm2 signal decreased in mid-S phase (Fig. 1C; Cdc45 associates with the pre-RC to form a preinitiation com- 35 min) and disappeared in late S phase (Fig. 1C; 40 min), plex (pre-IC) that is capable of origin unwinding and of pro- whereas the Cdc6 signal remained until early G2 phase (Fig. 1B; moting assembly of replication forks at replication origin. Thus, Cdc45 plays a crucial role in activation of replication origins. Although the mechanism of initiation of DNA replication is Author contributions: K.T., M.M., M.H., and T. Kishimoto designed research; K.T., M.M., T.M., well conserved, its control is diverse (3). In addition to evolu- T. Karino, T.I., A. Nagayama, A. Nishiyama, and M.H. performed research; K.T., M.M., T.M., tionary variation, DNA replication is regulated in response to M.H., and T. Kishimoto analyzed data; and K.T. and T. Kishimoto wrote the paper. developmental events in multicellular organisms. Fertilization is The authors declare no conflict of interest. the first major event in development and is necessary for both Data deposition: The sequences reported in this paper have been deposited in the DNA releasing meiotic arrest and restarting the cell cycle with ini- Data Bank of Japan (DDBJ) (accession nos. AB474909, AB474910, AB474911, AB474912, AB481214, AB481376, and AB530248). tiation of the first round of DNA replication. In some organisms, Drosophila – 1Present address: Gene Expression Unit, European Molecular Biology Laboratory (EMBL), including and echinoderms (4 6), fertilization is not a Meyerhofstrasse 1, D-69117 Heidelberg, Germany. prerequisite for the completion of meiosis, but required to trig- 2Present address: Laboratory of Replication and Genome Dynamics, Institute of Human ger entry into the first S phase and the subsequent cleavage Genetics, CNRS, 34396 Montpellier Cedex 5, France. fi Asterina pectinifera Patiria pecti- cycles. In star sh (renamed to 3To whom correspondence should be addressed. E-mail: [email protected]. nifera in 2007 at the NCBI Taxonomy Browser), the Mos-MAPK This article contains supporting information online at www.pnas.org/cgi/content/full/ (mitogen-activated protein kinase)-Rsk (p90 ribosomal S6 kin- 1000587107/DCSupplemental. 5006–5011 | PNAS | March 16, 2010 | vol. 107 | no. 11 www.pnas.org/cgi/doi/10.1073/pnas.1000587107 Downloaded by guest on September 27, 2021 A G1 S G2 M BrdU DNA Merge B Cdc6 DNA Merge C Mcm2 DNA Merge D Cdc45 DNA Merge 10 µm 0 5 10 15 20 25 30 35 40 45 50 55 60 Time after fertilization (min) E Insemination Pro-I MI IK MII G1 S G2 M Cdc45 0 30 60 90 120 150 180 210 Time after 1-MeAde addition (min) Fig. 1. In female pronuclei of starfish eggs, chromatin is loaded with Cdc6 and Mcm2 before fertilization, and then with Cdc45 after fertilization at G1/S- phase transition. (A) Mature eggs, which were arrested at G1 phase after completion of meiosis II, were inseminated. To monitor DNA replication, every 5 min, fertilized eggs were pulse labeled for 5 min with BrdU, extracted, and immunostained with anti-BrdU antibody (green). DNA was stained with DAPI (red). Insets indicate male chromatin, and main figures indicate female chromatin or fused chromatin. (B–D) Every 5 min, isolated eggs were extensively extracted and then immunostained with anti-starfish Cdc6 antibody (B, green), anti-starfish Mcm2 antibody (C, green), and anti-starfish Cdc45 antibody (D, green). (Scale bar, 10 μm.) (E) Cdc45 protein is detectable in immature oocytes and its levels remain constant during meiotic and cleavage cycles. 45 min), declined after mid-G2 phase (Fig. 1B; 50 min), and In male pronuclei, both Cdc6 and Mcm2 were undetectable finally disappeared at M phase (Fig. 1B; 60 min). Similar immediately after fertilization, and then soon became detecte- behavior of Mcm was observed with other antibodies against able (Fig. 1 B and C Insets;0∼20 min), indicating that male human Mcm2 (BM28) and starfish Mcm7 (Fig. S4). pronulei become licensed after fertilization. Indeed, undegrad- Before the G1 arrest, Mcm2 was detectable on chromatin at able form of geminin prevented DNA replication in male pro- each end of meiosis I and II during meiotic cycle, coincidentally nuclei (but not in female pronuclei) after fertilization, even when CELL BIOLOGY with decreased levels of cyclin B-Cdk1 activity (Fig. 2A). The it was introduced into G1-phase eggs (Fig. 2D, arrowhead). After Mcm2 loading was dependent on geminin degradation, sup- the loading onto chromatin, Cdc6 and Mcm2 behaved similarly porting that it was mediated by Cdt1 (Fig. 2 B and C) (13). to those in female pronuclei. Consistently, undegradable form of geminin prevented DNA replication in female pronuclei after fertilization, when it was Replication Origins Are Not Activated in Female Pronuclei of introduced into oocytes before, but not after, meiotic maturation Unfertilized Eggs. In contrast to Cdc6 and Mcm2, Cdc45 was (Fig. 2D). Taken together, pre-RC is already formed in female undetectable on chromatin in female pronuclei of unfertilized pronuclei of unfertilized eggs; that is, female pronuclei are G1-phase eggs (Fig.
Load more

Recommended publications
  • Differences in Pronucleus Formation and First Cleavage Following in Vitro Fertilization Between Pig Oocytes Matured in Vivo and in Vitro J
    Differences in pronucleus formation and first cleavage following in vitro fertilization between pig oocytes matured in vivo and in vitro J. Laurincik, D. Rath, and H. Niemann ^Research Institute of Animal Production, Hlohovska 2, 94992 Nitra, Slovak Republic; and zInstitut für Tierzucht und Tierverhalten (TAL) Mariensee, 31535 Neustadt, Germany To elucidate the developmental differences occurring after in vitro fertilization (IVF) of pig oocytes matured either in vitro (n = 1934) or in vivo (n = 1128), the present experiment investigated the morphological changes from penetration to the two-cell stage. Oocytes were examined every 2\p=n-\4h from 2 to 32 h after in vitro insemination to study sperm penetration, male and female pronucleus formation, synkaryosis and first cleavage. The penetration rate was significantly higher (P < 0.05) for in vivo matured oocytes (69.8%) than for in vitro matured oocytes (35.0%). Penetration of spermatozoa into the ooplasm was first recorded 6 h (in vitro matured oocytes) and 4 h (in vivo matured oocytes) after addition of the spermatozoa to the oocytes. For both in vivo and in vitro matured oocytes, 2 h were required for sperm head decondensation. However, maximum sperm head decondensation occurred 2 h later in in vitro matured oocytes. Within 6 h, 41.7 \m=+-\5.6% of the in vivo matured oocytes had completed second meiotic division, whereas only 20.8 \m=+-\6.5% of the in vitro matured oocytes reached this developmental stage (P < 0.01). For in vitro matured oocytes, male pronucleus formation was retarded 2\p=n-\4h after onset of insemination and develop- ment of the female pronucleus was enhanced compared with in vivo matured oocytes.
    [Show full text]
  • An Investigation Into Pronuclear Migration in Fertilized Sea Urchin Cells
    An Investigation into Pronuclear Migration in Fertilized Sea Urchin Cells Author: Sean Patrick Ruvolo Persistent link: http://hdl.handle.net/2345/bc-ir:107271 This work is posted on eScholarship@BC, Boston College University Libraries. Boston College Electronic Thesis or Dissertation, 2016 Copyright is held by the author, with all rights reserved, unless otherwise noted. Boston College Graduate School of Arts and Sciences Department of Biology AN INVESTIGATION INTO PRONUCLEAR MIGRATION IN FERTILIZED SEA URCHIN CELLS a thesis by SEAN PATRICK RUVOLO submitted in partial fulfillment of the requirements for the degree of Master of Science October 2016 © Copyright by Sean Patrick Ruvolo 2016 An Investigation into Pronuclear Migration in Fertilized Sea Urchin Cells Sean Patrick Ruvolo Advisor: David Burgess, Ph.D. After fertilization, centration of the nucleus is a necessary first step for ensuring proper cell division and embryonic development in many proliferating cells such as the sea urchin. In order for the nucleus to migrate to the cell center, the sperm aster must first capture the female pronucleus for fusion. While microtubules (MTs) are known to be necessary for centration, the precise mechanisms for both capture and centration remain undetermined. Therefore, the purpose of this research was to investigate the role of MTs in nuclear centration. Fertilized sea urchin cells were treated with the pharmacological agent, urethane (ethyl carbamate), in order to induce MT catastrophe and shrink MT asters during pronuclear capture and centration. It was discovered that proper MT length and proximity are required for pronuclear capture, since diminished asters could not interact with the female pronucleus at opposite ends of the cell.
    [Show full text]
  • Examination of Early Cleavage an Its Importance in IVF Treatment Fancsovits P, Takacs FZ, Tothne GZ, Papp Z Urbancsek J J
    Journal für Reproduktionsmedizin und Endokrinologie – Journal of Reproductive Medicine and Endocrinology – Andrologie • Embryologie & Biologie • Endokrinologie • Ethik & Recht • Genetik Gynäkologie • Kontrazeption • Psychosomatik • Reproduktionsmedizin • Urologie Examination of Early Cleavage an its Importance in IVF Treatment Fancsovits P, Takacs FZ, Tothne GZ, Papp Z Urbancsek J J. Reproduktionsmed. Endokrinol 2006; 3 (6), 367-372 www.kup.at/repromedizin Online-Datenbank mit Autoren- und Stichwortsuche Offizielles Organ: AGRBM, BRZ, DVR, DGA, DGGEF, DGRM, D·I·R, EFA, OEGRM, SRBM/DGE Indexed in EMBASE/Excerpta Medica/Scopus Krause & Pachernegg GmbH, Verlag für Medizin und Wirtschaft, A-3003 Gablitz FERRING-Symposium digitaler DVR 2021 Mission possible – personalisierte Medizin in der Reproduktionsmedizin Was kann die personalisierte Kinderwunschbehandlung in der Praxis leisten? Freuen Sie sich auf eine spannende Diskussion auf Basis aktueller Studiendaten. SAVE THE DATE 02.10.2021 Programm 12.30 – 13.20Uhr Chair: Prof. Dr. med. univ. Georg Griesinger, M.Sc. 12:30 Begrüßung Prof. Dr. med. univ. Georg Griesinger, M.Sc. & Dr. Thomas Leiers 12:35 Sind Sie bereit für die nächste Generation rFSH? Im Gespräch Prof. Dr. med. univ. Georg Griesinger, Dr. med. David S. Sauer, Dr. med. Annette Bachmann 13:05 Die smarte Erfolgsformel: Value Based Healthcare Bianca Koens 13:15 Verleihung Frederik Paulsen Preis 2021 Wir freuen uns auf Sie! Examination of Early Cleavage and its Importance in IVF Treatment P. Fancsovits, F. Z. Takács, G. Z. Tóthné, Z. Papp, J. Urbancsek Since the introduction of assisted reproduction, the number of multiple pregnancies has increased due to the high number of transferred embryos. There is an urgent need for IVF specialists to reduce the number of embryos transferred without the risk of decreasing pregnancy rates.
    [Show full text]
  • Does Mitochondrial Replacement Therapy Violate Laws Against Human Cloning?
    Loyola of Los Angeles International and Comparative Law Review Volume 43 Number 3 Article 5 2021 Does Mitochondrial Replacement Therapy Violate Laws Against Human Cloning? Kerry Lynn Macintosh Follow this and additional works at: https://digitalcommons.lmu.edu/ilr Part of the Health Law and Policy Commons, and the Science and Technology Law Commons Recommended Citation Kerry Lynn Macintosh, Does Mitochondrial Replacement Therapy Violate Laws Against Human Cloning?, 43 Loy. L.A. Int'l & Comp. L. Rev. 251 (2021). Available at: https://digitalcommons.lmu.edu/ilr/vol43/iss3/5 This Article is brought to you for free and open access by the Law Reviews at Digital Commons @ Loyola Marymount University and Loyola Law School. It has been accepted for inclusion in Loyola of Los Angeles International and Comparative Law Review by an authorized administrator of Digital Commons@Loyola Marymount University and Loyola Law School. For more information, please contact [email protected]. TECH_TO_EIC 5/19/21 3:50 PM Does Mitochondrial Replacement Therapy Violate Laws Against Human Cloning? BY KERRY LYNN MACINTOSH* INTRODUCTION All human beings have mitochondria within their cells that produce energy.1 Most of us inherit healthy mitochondria through the eggs of our mothers,2 but some of us are not so lucky. Mutations in mitochondrial DNA (mtDNA) can cause these tiny organelles to function improperly and disrupt tissues that require a lot of energy, like the brain, kidney, liver, heart, muscle, and central nervous system.3 For example, a specific mtDNA mutation induces Leigh syndrome, a condition in which seizures and respiratory failure lead to decline in mental and motor skills, disabil- ity, and death.4 Mitochondrial replacement therapy (MRT) offers a solution to this problem.
    [Show full text]
  • EHMT2 and SETDB1 Protect the Maternal Pronucleus from 5Mc Oxidation
    EHMT2 and SETDB1 protect the maternal pronucleus from 5mC oxidation Tie-Bo Zenga, Li Hana,1, Nicholas Piercea, Gerd P. Pfeifera, and Piroska E. Szabóa,2 aCenter for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503 Edited by Shirley M. Tilghman, Princeton University, Princeton, NJ, and approved April 19, 2019 (received for review November 21, 2018) Genome-wide DNA “demethylation” in the zygote involves global somewhat less 5mC (8). Global loss of DNA methylation takes TET3-mediated oxidation of 5‐methylcytosine (5mC) to 5-hydroxy- place after fertilization in both the paternal and maternal ge- methylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcyto- nomes, but with different dynamics and a different level of sine (5caC) in the paternal pronucleus. Asymmetrically enriched contribution of active and passive processes (17–19). Removal of histoneH3K9methylationinthe maternal pronucleus was sug- 5‐methylcytosine (5mC) in the maternal genome occurs slowly gested to protect the underlying DNA from 5mC conversion. We and predominantly by passive dilution during DNA replication. hypothesized that an H3K9 methyltransferase enzyme, either The paternal genome, however, undergoes a rapid loss of 5mC. EHMT2 or SETDB1, must be expressed in the oocyte to specify the We, and others, have reported that this genome-wide active DNA asymmetry of 5mC oxidation. To test these possibilities, we genet- “demethylation” involves global TET3-mediated oxidation of 5mC ically deleted the catalytic domain of either EHMT2 or SETDB1 in to 5hmC, 5fC, and 5caC in the paternal pronucleus (20–25). growing oocytes and achieved significant reduction of global The asymmetry of 5mC oxidation between the two paren- H3K9me2 or H3K9me3 levels, respectively, in the maternal pronu- tal pronuclei depends on the asymmetry of H3K9 methylation cleus.
    [Show full text]
  • Third Scientific Review of the Safety and Efficacy of Methods to Avoid Mitochondrial Disease Through Assisted Conception: 2014 Update
    Third scientific review of the safety and efficacy of methods to avoid mitochondrial disease through assisted conception: 2014 update Report provided to the Human Fertilisation and Embryology Authority (HFEA), June 2014 Review panel chair: Dr Andy Greenfield, Medical Research Council (MRC) Harwell and HFEA member Contents Executive summary 3 1. Introduction, scope and objectives 9 2. Review of preimplantation genetic diagnosis (PGD) to 12 avoid mitochondrial disease 3. Review of maternal spindle transfer (MST) and pronuclear 14 transfer (PNT) to avoid mitochondrial disease 4. Recommendations and further research 37 Annexes Annex A: Methodology of review 41 Annex B: Evidence reviewed 42 Annex C: Summary of recommendations for further research made 46 in 2011, 2013, 2014 Annex D: Glossary of terms 52 2 Executive summary Mitochondria are small structures present in cells that produce much of the energy required by the cell. They contain a small amount of DNA that is inherited exclusively from the mother through the mitochondria present in her eggs. Mutations in this mitochondrial DNA (mtDNA) can cause a range of rare but serious diseases, which can be fatal. However, there are several novel treatment methods with the potential to reduce the transmission of abnormal mtDNA from a mother to her child, and thus avoid mitochondrial disease in the child and subsequent generations. Such treatments have not been carried out in humans anywhere in the world and they are currently illegal in the UK. This is because the primary legislation that governs assisted reproduction, the Human Fertilisation and Embryology (HFE) Act 1990 (as amended), only permits eggs and embryos that have not had their nuclear or mtDNA altered to be used for treatment.
    [Show full text]
  • Mitochondrial DNA Replacement Techniques to Prevent Human Mitochondrial Diseases
    International Journal of Molecular Sciences Review Mitochondrial DNA Replacement Techniques to Prevent Human Mitochondrial Diseases Luis Sendra 1,2 , Alfredo García-Mares 2, María José Herrero 1,2,* and Salvador F. Aliño 1,2,3 1 Unidad de Farmacogenética, Instituto de Investigación Sanitaria La Fe, 46026 Valencia, Spain; [email protected] (L.S.); [email protected] (S.F.A.) 2 Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, 46010 Valencia, Spain; [email protected] 3 Unidad de Farmacología Clínica, Área del Medicamento, Hospital Universitario y Politécnico La Fe, 46026 Valencia, Spain * Correspondence: [email protected]; Tel.: +34-961-246-675 Abstract: Background: Mitochondrial DNA (mtDNA) diseases are a group of maternally inherited genetic disorders caused by a lack of energy production. Currently, mtDNA diseases have a poor prognosis and no known cure. The chance to have unaffected offspring with a genetic link is important for the affected families, and mitochondrial replacement techniques (MRTs) allow them to do so. MRTs consist of transferring the nuclear DNA from an oocyte with pathogenic mtDNA to an enucleated donor oocyte without pathogenic mtDNA. This paper aims to determine the efficacy, associated risks, and main ethical and legal issues related to MRTs. Methods: A bibliographic review was performed on the MEDLINE and Web of Science databases, along with searches for related clinical trials and news. Results: A total of 48 publications were included for review. Five MRT procedures were identified and their efficacy was compared. Three main risks associated with MRTs were discussed, and the ethical views and legal position of MRTs were reviewed.
    [Show full text]
  • Microtubule-Based Mechanisms of Pronuclear Positioning
    cells Review Microtubule-Based Mechanisms of Pronuclear Positioning Johnathan L. Meaders and David R. Burgess * Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-617-552-1606 Received: 3 February 2020; Accepted: 19 February 2020; Published: 23 February 2020 Abstract: The zygote is defined as a diploid cell resulting from the fusion of two haploid gametes. Union of haploid male and female pronuclei in many animals occurs through rearrangements of the microtubule cytoskeleton into a radial array of microtubules known as the sperm aster. The sperm aster nucleates from paternally-derived centrioles attached to the male pronucleus after fertilization. Nematode, echinoderm, and amphibian eggs have proven as invaluable models to investigate the biophysical principles for how the sperm aster unites male and female pronuclei with precise spatial and temporal regulation. In this review, we compare these model organisms, discussing the dynamics of sperm aster formation and the different force generating mechanism for sperm aster and pronuclear migration. Finally, we provide new mechanistic insights for how sperm aster growth may influence sperm aster positioning. Keywords: dynein; pronucleus; microtubule; MTOC; microtubule aster; zygote; oocyte 1. Introduction The mature oocyte is the starting point of what eventually becomes a fully developed organism composed of multiple organ systems, multicellular tissues, and a multitude of differentiated and undifferentiated cell types in most animals. The first stage of this transformation begins with one of the most complex transitions in cellular and developmental biology—remodeling the oocyte into a totipotent zygote. Even more noteworthy is the fact that the oocyte contains almost everything required, from mRNA transcripts to molecular signaling proteins and machinery, to guide the oocyte-to-zygote transition [1].
    [Show full text]
  • Initiation of DNA Replication After Fertilization Is Regulated by P90rsk at Pre-RC/Pre-IC Transition in Starfish Eggs
    Initiation of DNA replication after fertilization is regulated by p90Rsk at pre-RC/pre-IC transition in starfish eggs Kazunori Tachibana, Masashi Mori1, Takashi Matsuhira, Tomotake Karino, Takuro Inagaki, Ai Nagayama, Atsuya Nishiyama2, Masatoshi Hara, and Takeo Kishimoto3 Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Yokohama 226-8501, Japan Communicated by Joan Ruderman, Harvard Medical School, Boston, MA, January 17, 2010 (received for review August 31, 2009) Initiation of DNA replication in eukaryotic cells is controlled through ase, p90Rsk) pathway causes the G1-phase arrest at the pronu- an ordered assembly of protein complexes at replication origins. The cleus stage (6–10). Fertilization induces degradation of Mos to molecules involved in this process are well conserved but diversely shutdown this pathway, leading to the first S phase with no regulated. Typically, initiation of DNA replication is regulated in requirement of new protein synthesis. However, it remains response to developmental events in multicellular organisms. Here, unclear how p90Rsk negatively controls the G1/S-phase tran- we elucidate the regulation of the first S phase of the embryonic cell sition, or to which stage the initiation complex for DNA repli- cycle after fertilization. Unless fertilization occurs, the Mos-MAPK- cation is assembled in unfertilized G1-phase eggs. Here we show p90Rsk pathway causes the G1-phase arrest after completion of that the p90Rsk-dependent G1-phase arrest of unfertilized meiosis in starfish eggs. Fertilization shuts down this pathway, starfish eggs occurs at the pre-RC stage, and that in the absence leading to the first S phase with no requirement of new protein of Cdk1 and Cdk2 activities and Cdc7 accumulation, inactivation synthesis.
    [Show full text]
  • Ideas in Ecology and Evolution 1: 1-10, 2008
    Ideas in Ecology and Evolution 4: 14-23, 2011 doi:10.4033/iee.2011.4.3.n © 2011 The Author. © Ideas in Ecology and Evolution 2011 iee Received 12 April 2011; Accepted 30 August 2011 New Idea Post-plasmogamic pre-karyogamic sexual selection: mate choice inside an egg cell Root Gorelick1,2, Lindsay Jackson Derraugh1, Jessica Carpinone1, and Susan M. Bertram Root Gorelick ([email protected]), Dept. of Biology, and School of Mathematics & Statistics, Carleton University, 1125 Colonel By, Ottawa, Ontario, CANADA K1S 5B6 Lindsay Jackson Derraugh ([email protected]), Dept. of Biology, Carleton University, 1125 Colonel By, Ottawa Ontario, CANADA K1S 5B6 Jessica Carprinone ([email protected]), Dept. of Biology, Carleton University, 1125 Colonel By, Ottawa Ontario, CANADA K1S 5B6 Susan M. Bertram ([email protected]), Dept. of Biology, Carleton University, 1125 Colonel By, Ottawa Ontario, CANADA K1S 5B6 1The first three authors contributed equally to the manuscript. 2Corresponding author Abstract Intersexual selection is often categorized as pre- Key Words: Sexual selection, cryptic female choice, copulatory or post-copulatory mate choice by indiv- pronucleus, polyspermy, gynogenesis, androgenesis. iduals of one sex over showy individuals of the other sex. We extend the framework of post-copulatory choice to include post-plasmogamic pre-karyogamic Introduction sexual selection. That is, selection of haploid nuclei within the microcosm of a single fertilized egg cell after Charles Darwin (1871) first introduced the idea of sperm has entered an egg cell but before fusion of their sexual selection to account for the differences in nuclear membranes, in which an egg nucleus chooses a secondary sexual characteristics that could not be sperm nucleus with which to fuse.
    [Show full text]
  • ONPRC Module 3A: Assisted Reproductive Technologies (ART)
    1 ONPRC Module 3A: Assisted Reproductive Technologies (ART) Guiding Question: How can we preserve the fertility of cancer patients? Module Question Laboratory Questions How does learning • How does fertilization happen in humans, in vivo and in about fertilization, vitro? embryonic development and assisted • How do embryos develop? reproductive technologies create options for preserving • How can we monitor pregnancy using ultrasound? fertility? Learning Outcomes: Describe the process of fertilization. Describe embryonic and early fetal development. Describe assisted reproductive technologies (artificial insemination, in vitro fertilization, intracytoplasmic sperm injection). Describe how assisted reproductive technologies can help preserve endangered species. Describe how assisted reproductive technologies can help preserve the fertility of cancer patients. This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. 2 Fertilization Process http://commons.wikimedia.org/wiki/File:Sperm-egg.jpg Steps for Forming a Fertilized Egg 1. Sperm bind to zona pellucida proteins (ZPs) – specific to every species except hamster 2. Sperm undergoes acrosome reaction so it can digest through the zona pellucida 3. Sperm fuses with oocyte plasma membrane = fertilization and enters oocyte; only 1 sperm in 1,000,000 will make it to fertilization. 4. Cortical reaction occurs, “hardens” oocyte membrane, no more sperm can enter 5. Zona reaction occurs, destroys ZPs so no more sperm can bind 3 Fertilization
    [Show full text]
  • Centrosome Attachment to the C. Elegans Male Pronucleus Is Dependent on the Surface Area of the Nuclear Envelope
    Developmental Biology 327 (2009) 433–446 Contents lists available at ScienceDirect Developmental Biology journal homepage: www.elsevier.com/developmentalbiology Centrosome attachment to the C. elegans male pronucleus is dependent on the surface area of the nuclear envelope Marina Meyerzon a, Zhizhen Gao b, Jin Liu a, Jui-Ching Wu a, Christian J. Malone b, Daniel A. Starr a,⁎ a Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA b Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA article info abstract Article history: A close association must be maintained between the male pronucleus and the centrosomes during Received for publication 30 April 2008 pronuclear migration. In C. elegans, simultaneous depletion of inner nuclear membrane LEM proteins EMR-1 Revised 13 December 2008 and LEM-2, depletion of the nuclear lamina proteins LMN-1 or BAF-1, or the depletion of nuclear import Accepted 19 December 2008 components leads to embryonic lethality with small pronuclei. Here, a novel centrosome detachment Available online 3 January 2009 phenotype in C. elegans zygotes is described. Zygotes with defects in the nuclear envelope had small pronuclei with a single centrosome detached from the male pronucleus. ZYG-12, SUN-1, and LIS-1, which Keywords: Nuclear envelope function at the nuclear envelope with dynein to attach centrosomes, were observed at normal concentrations Centrosome on the nuclear envelope of pronuclei with detached centrosomes. Analysis of time-lapse images showed that Male pronucleus as mutant pronuclei grew in surface area, they captured detached centrosomes. Larger tetraploid or smaller Pronuclear migration histone::mCherry pronuclei suppressed or enhanced the centrosome detachment phenotype respectively.
    [Show full text]