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zygote activation

Tetsuya Ishii, Yuri Hibino
The clinical uses of cytoplasmic transfer and pronuclear transfer for infertility treatment have raised concerns, leading to restrictive regulatory responses in both the USA and China. In 2015, the UK legalized nuclear transfer from oocytes and zygotes to prevent the onset of serious mitochondrial disease in the children of affected mothers. A research team in the USA then performed egg nuclear transfer, with subsequent embryo transfer in Mexico, to prevent mitochondrial disease. A live birth resulted, but the cross-border activity attracted attention from regulatory authorities...
April 2018: Reproductive Biomedicine & Society Online
Matthew M Wong, Mezmur D Belew, Amanda Kwieraga, James D Nhan, W Matthew Michael
In Caenorhabditis elegans, the primordial germ cells Z2 and Z3 are born during early embryogenesis and then held in a transcriptionally quiescent state where the genome is highly compacted. When hatched L1s feed, the germline genome decompacts, and RNAPII is abruptly and globally activated. A previously documented yet unexplained feature of germline genome activation in the worm is the appearance of numerous DNA breaks coincident with RNAPII transcription. Here, we show that the DNA breaks are induced by topoisomerase II and that they function to recruit the RUVB complex to chromosomes so that RUVB can decompact the chromatin...
August 6, 2018: Developmental Cell
Yan-Yi Xing, Xiao-Ning Cheng, Yu-Long Li, Chong Zhang, Audrey Saquet, Yuan-Yuan Liu, Ming Shao, De-Li Shi
Wnt signaling plays critical roles in dorsoventral fate specification and anteroposterior patterning, as well as in morphogenetic cell movements. Dishevelled proteins, or Dvls, mediate the activation of Wnt/ß-catenin and Wnt/planar cell polarity pathways. There are at least three highly conserved Dvl proteins in vertebrates, but the implication of each Dvl in key early developmental processes remains poorly understood. In this study, we use genome-editing approach to generate different combinations of maternal and zygotic dvl mutants in zebrafish, and examine their functions during early development...
August 6, 2018: PLoS Genetics
Aliki Anyfantaki, Christiana Kyvelidou, Margarita Tsagkaraki, George Filippidis, Mattheos Fraidakis, Alexandros Zafiropoulos, Irene Athanassakis
Implantation failure is a major problem in human assisted reproduction, which persists regardless the optimization of endometrial receptivity and selection of genetically and morphologically healthy embryos. Since embryo-endometrium interaction depends on cell junctional, cell adhesion and cell-substratum adhesion molecules, the present study inquired whether in vitro growing murine embryos display similar to the in vivo growing embryos patterns of adhesion molecules. To this extend aVb3 expression and distribution in zygotes and 2-cell stage embryos were studied...
August 3, 2018: Reproductive Biology
Ricardo Fuentes, Mary C Mullins, Juan Fernández
Establishment and movement of cytoplasmic domains is of great importance for the emergence of cell polarity, germline segregation, embryonic axis specification and correct sorting of organelles and macromolecules into different embryonic cells. The zebrafish oocyte, egg and zygote are valuable material for the study of cytoplasmic domains formation and dynamics during development. In this review we examined how cytoplasmic domains form and are relocated during zebrafish early embryogenesis. Distinct cortical cytoplasmic domains (also referred to as ectoplasm domains) form first during early oogenesis by the localization of mRNAs to the vegetal or animal poles of the oocyte or radially throughout the cortex...
August 2, 2018: Mechanisms of Development
Feifei Shi, Hua Li, Enling Wang, Zi-Jiang Chen, Cong Zhang
Embryo development block seriously limits the success of in vitro embryo production and assisted reproductive technology. Although numerous researchers have explored this problem, it remains to be solved. In this study, we found that melatonin supplementation at 10-8 and 10-9 M in M16 significantly reduced two-cell block of mouse embryos. When those melatonin-treated four-cell embryos were transplanted into the oviducts of female recipient mice, the litter sizes were significantly increased compared with those of the controls...
August 3, 2018: Journal of Cellular Biochemistry
Jean-Denis Beaudoin, Eva Maria Novoa, Charles E Vejnar, Valeria Yartseva, Carter M Takacs, Manolis Kellis, Antonio J Giraldez
RNA folding plays a crucial role in RNA function. However, knowledge of the global structure of the transcriptome is limited to cellular systems at steady state, thus hindering the understanding of RNA structure dynamics during biological transitions and how it influences gene function. Here, we characterized mRNA structure dynamics during zebrafish development. We observed that on a global level, translation guides structure rather than structure guiding translation. We detected a decrease in structure in translated regions and identified the ribosome as a major remodeler of RNA structure in vivo...
August 2018: Nature Structural & Molecular Biology
German Nudelman, Antonio Frasca, Brandon Kent, Kirsten C Sadler, Stuart C Sealfon, Martin J Walsh, Elena Zaslavsky
With the emergence of zebrafish as an important model organism, a concerted effort has been made to study its transcriptome. This effort is limited, however, by gaps in zebrafish annotation, which are especially pronounced concerning transcripts dynamically expressed during zygotic genome activation (ZGA). To date, short-read sequencing has been the principal technology for zebrafish transcriptome annotation. In part because these sequence reads are too short for assembly methods to resolve the full complexity of the transcriptome, the current annotation is rudimentary...
July 30, 2018: Genome Research
Hiroki Sasaguri, Kenichi Nagata, Misaki Sekiguchi, Ryo Fujioka, Yukio Matsuba, Shoko Hashimoto, Kaori Sato, Deepika Kurup, Takanori Yokota, Takaomi C Saido
Base Editor (BE) and Target-AID (activation-induced cytidine deaminase) are engineered genome-editing proteins composed of Cas9 and cytidine deaminases. These base-editing tools convert C:G base pairs to T:A at target sites. Here, we inject either BE or Target-AID mRNA together with identical single-guide RNAs (sgRNAs) into mouse zygotes, and compare the base-editing efficiencies of the two distinct tools in vivo. BE consistently show higher base-editing efficiency (10.0-62.8%) compared to that of Target-AID (3...
July 24, 2018: Nature Communications
Peter L Pfeffer
The self-organisation of a fertilised egg to form a blastocyst structure, which consists of three distinct cell lineages (trophoblast, epiblast and hypoblast) arranged around an off-centre cavity, is unique to mammals. While the starting point (the zygote) and endpoint (the blastocyst) are similar in all mammals, the intervening events have diverged. This review examines and compares the descriptive and functional data surrounding embryonic gene activation, symmetry-breaking, first and second lineage establishment, and fate commitment in a wide range of mammalian orders...
July 23, 2018: Biology
Jinsong Liu
Life starts with a zygote which is formed via fusion of haploid sperm and egg. The formation of blastomere via cleavage division (nuclear division without increase in cell size) is the first step in the embryogenesis after zygote. The blastomeres are responsible to reprogram parental genome to new embryonic genome for generation of pluripotent stem cells which then differentiate via Waddington's epigenetic landscape to give a birth for a new life. Multiple authors over the past century and a half have proposed that tumor arises from development gone awry along the Waddington's landscape...
July 21, 2018: Seminars in Cancer Biology
Pedro Prudêncio, Leonardo G Guilgur, João Sobral, Jörg D Becker, Rui Gonçalo Martinho, Paulo Navarro-Costa
The transition from fertilized oocyte to totipotent embryo relies on maternal factors that are synthetized and accumulated during oocyte development. Yet, it is unclear how oocytes regulate the expression of maternal genes within the transcriptional program of oogenesis. Here, we report that the Drosophila Trithorax group protein dMLL3/4 (also known as Trr) is essential for the transition to embryo fate at fertilization. In the absence of dMLL3/4, oocytes develop normally but fail to initiate the embryo mitotic divisions after fertilization...
August 2018: EMBO Reports
Maria Cristina Gambetta, Eileen E M Furlong
Insulator binding proteins (IBPs) play an important role in regulating gene expression by binding to specific DNA sites to facilitate appropriate gene regulation. There are several IBPs in Drosophila , each defined by their ability to insulate target gene promoters in transgenic assays from the activating or silencing effects of neighboring regulatory elements. Of these, only CCCTC-binding factor (CTCF) has an obvious ortholog in Mammals. CTCF is essential for mammalian cell viability and is an important regulator of genome architecture...
July 18, 2018: Genetics
Tomoaki Nishiyama, Hidetoshi Sakayama, Jan de Vries, Henrik Buschmann, Denis Saint-Marcoux, Kristian K Ullrich, Fabian B Haas, Lisa Vanderstraeten, Dirk Becker, Daniel Lang, Stanislav Vosolsobě, Stephane Rombauts, Per K I Wilhelmsson, Philipp Janitza, Ramona Kern, Alexander Heyl, Florian Rümpler, Luz Irina A Calderón Villalobos, John M Clay, Roman Skokan, Atsushi Toyoda, Yutaka Suzuki, Hiroshi Kagoshima, Elio Schijlen, Navindra Tajeshwar, Bruno Catarino, Alexander J Hetherington, Assia Saltykova, Clemence Bonnot, Holger Breuninger, Aikaterini Symeonidi, Guru V Radhakrishnan, Filip Van Nieuwerburgh, Dieter Deforce, Caren Chang, Kenneth G Karol, Rainer Hedrich, Peter Ulvskov, Gernot Glöckner, Charles F Delwiche, Jan Petrášek, Yves Van de Peer, Jiri Friml, Mary Beilby, Liam Dolan, Yuji Kohara, Sumio Sugano, Asao Fujiyama, Pierre-Marc Delaux, Marcel Quint, Günter Theißen, Martin Hagemann, Jesper Harholt, Christophe Dunand, Sabine Zachgo, Jane Langdale, Florian Maumus, Dominique Van Der Straeten, Sven B Gould, Stefan A Rensing
Land plants evolved from charophytic algae, among which Charophyceae possess the most complex body plans. We present the genome of Chara braunii; comparison of the genome to those of land plants identified evolutionary novelties for plant terrestrialization and land plant heritage genes. C. braunii employs unique xylan synthases for cell wall biosynthesis, a phragmoplast (cell separation) mechanism similar to that of land plants, and many phytohormones. C. braunii plastids are controlled via land-plant-like retrograde signaling, and transcriptional regulation is more elaborate than in other algae...
July 12, 2018: Cell
Fumei Chen, Qiang Fu, Liping Pu, Pengfei Zhang, Yulin Huang, Zhen Hou, Zhuangzhuang Xu, Dongrong Chen, Fengling Huang, Tingxian Deng, Xianwei Liang, Yangqing Lu, Ming Zhang
Maternal-effect genes are especially critical for early embryonic development after fertilization and until massive activation of the embryonic genome occurs. By applying a tandem mass tag (TMT)-labeled quantitative proteomics combined with RNA sequencing approach, the proteome of the buffalo was quantitatively analyzed during parthenogenesis of mature oocytes and the two-cell stage embryo. Of 1,908 quantified proteins, 123 differed significantly. The transcriptome was analyzed eight stages (GV, MII, 2-cell, 4-cell, 8-cell, 16-cell, morula, blastocyst) of Buffalo using the RNA sequencing approach , and a total of 3567 unique genes were identified to be differently expressed between all consecutive stages of pre-implantation development...
July 12, 2018: Molecular & Cellular Proteomics: MCP
Valérie Gautier, Laetitia Chan Ho Tong, Tinh-Suong Nguyen, Robert Debuchy, Philippe Silar
Filamentous fungi frequently undergo bistable phenotypic switches. Crippled Growth of Podospora anserina is one such bistable switch, which seems to rely upon the mis-activation of a self-regulated PaMpk1 MAP kinase regulatory pathway. Here, we identify two new partners of this pathway: PaPro1, a transcription factor orthologous to Sordaria macrospora pro1 and Neurospora crassa ADV-1, and IDC4, a protein with an AIM24 domain. Both PaPro1 and IDC4 regulate stationary phase features, as described for the other actors of the PaMpk1 signaling pathway...
July 11, 2018: Journal of Fungi (Basel, Switzerland)
Yean Ju Hong, Kwonho Hong, Seki Byun, Hyun Woo Choi, Jeong Tae Do
Pluripotential reprogramming has been examined using various technologies including nuclear transfer, cell fusion, and direct reprogramming. Many studies have used differentiated cells for reprogramming experiments, and nearly all type of somatic cells can acquire pluripotency. However, within the embryo, other cells types are present in addition to somatic cells. The blastocyst stage embryo consists of two main types of cells, inner cell mass and trophectoderm. Trophectoderm cells are the first differentiated form of the totipotent zygote and differ from epiblast cells...
July 11, 2018: Stem Cells and Development
Babu Ram Paudel, Martin Burd, Mani Shrestha, Adrian G Dyer, Qing-Jun Li
Multiple barriers may contribute to reproductive isolation between closely related species. Understanding the relative strength of these barriers can illuminate the ecological factors that currently maintain species integrity and how these factors originally promoted speciation. Two Himalayan alpine gingers, Roscoea purpurea and R. tumjensis, occur sympatrically in central Nepal and have such similar morphology that it is not clear whether or how they maintain a distinct identity. Our quantitative measurements of the components of reproductive isolation show that they are, in fact, completely isolated by a combination of phenological displacement of flowering, earlier for R...
July 10, 2018: Evolution; International Journal of Organic Evolution
Courtney W Hanna, Hannah Demond, Gavin Kelsey
BACKGROUND: Over the past few years, advances in molecular technologies have allowed unprecedented mapping of epigenetic modifications in gametes and during early embryonic development. This work is allowing a detailed genomic analysis, which for the first time can answer long-standing questions about epigenetic regulation and reprogramming, and highlights differences between mouse and human, the implications of which are only beginning to be explored. OBJECTIVE AND RATIONALE: In this review, we summarise new low-cell molecular methods enabling the interrogation of epigenetic information in gametes and early embryos, the mechanistic insights these have provided, and contrast the findings in mouse and human...
July 10, 2018: Human Reproduction Update
Willian T A F Silva
The starting point of a new generation in sexually reproducing species is fertilization. In many species, fertilization is followed by cell divisions controlled primarily by maternal transcripts, with little to no zygotic transcription. The activation of the zygotic genome (ZGA) is part of a process called maternal-to-zygotic transition (MZT), during which transcripts from the zygotic genome take control of development, setting the conditions for cellular specialization. While we know that epigenetic processes (e...
2018: PloS One
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