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Hasley A, Chavez S, Danilchik M, Wühr M, Pelegri F. Vertebrate Embryonic Cleavage Pattern Determination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:117-171. [PMID: 27975272 PMCID: PMC6500441 DOI: 10.1007/978-3-319-46095-6_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pattern of the earliest cell divisions in a vertebrate embryo lays the groundwork for later developmental events such as gastrulation, organogenesis, and overall body plan establishment. Understanding these early cleavage patterns and the mechanisms that create them is thus crucial for the study of vertebrate development. This chapter describes the early cleavage stages for species representing ray-finned fish, amphibians, birds, reptiles, mammals, and proto-vertebrate ascidians and summarizes current understanding of the mechanisms that govern these patterns. The nearly universal influence of cell shape on orientation and positioning of spindles and cleavage furrows and the mechanisms that mediate this influence are discussed. We discuss in particular models of aster and spindle centering and orientation in large embryonic blastomeres that rely on asymmetric internal pulling forces generated by the cleavage furrow for the previous cell cycle. Also explored are mechanisms that integrate cell division given the limited supply of cellular building blocks in the egg and several-fold changes of cell size during early development, as well as cytoskeletal specializations specific to early blastomeres including processes leading to blastomere cohesion. Finally, we discuss evolutionary conclusions beginning to emerge from the contemporary analysis of the phylogenetic distributions of cleavage patterns. In sum, this chapter seeks to summarize our current understanding of vertebrate early embryonic cleavage patterns and their control and evolution.
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Affiliation(s)
- Andrew Hasley
- Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA
| | - Shawn Chavez
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Physiology & Pharmacology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Obstetrics & Gynecology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA
| | - Michael Danilchik
- Department of Integrative Biosciences, L499, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Martin Wühr
- Department of Molecular Biology & The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Icahn Laboratory, Washington Road, Princeton, NJ, 08544, USA
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA.
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Baars DL, Takle KA, Heier J, Pelegri F. Ploidy Manipulation of Zebrafish Embryos with Heat Shock 2 Treatment. J Vis Exp 2016:54492. [PMID: 28060351 PMCID: PMC5180577 DOI: 10.3791/54492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Manipulation of ploidy allows for useful transformations, such as diploids to tetraploids, or haploids to diploids. In the zebrafish Danio rerio, specifically the generation of homozygous gynogenetic diploids is useful in genetic analysis because it allows the direct production of homozygotes from a single heterozygous mother. This article describes a modified protocol for ploidy duplication based on a heat pulse during the first cell cycle, Heat Shock 2 (HS2). Through inhibition of centriole duplication, this method results in a precise cell division stall during the second cell cycle. The precise one-cycle division stall, coupled to unaffected DNA duplication, results in whole genome duplication. Protocols associated with this method include egg and sperm collection, UV treatment of sperm, in vitro fertilization and heat pulse to cause a one-cell cycle division delay and ploidy duplication. A modified version of this protocol could be applied to induce ploidy changes in other animal species.
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Affiliation(s)
| | - Kendra A Takle
- Laboratory of Genetics, University of Wisconsin; Department of Neurobiology, University of Massachusetts Medical School
| | - Jonathon Heier
- Laboratory of Genetics, University of Wisconsin; Interdisciplinary Biomedical Graduate Program, University of Pittsburgh School of Medicine
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Localization in Oogenesis of Maternal Regulators of Embryonic Development. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 953:173-207. [DOI: 10.1007/978-3-319-46095-6_5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Nukada Y, Horie M, Fukui A, Kotani T, Yamashita M. Real-time imaging of actin filaments in the zebrafish oocyte and embryo. Cytoskeleton (Hoboken) 2015; 72:491-501. [PMID: 26335601 DOI: 10.1002/cm.21253] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 08/09/2015] [Accepted: 08/26/2015] [Indexed: 01/01/2023]
Abstract
Dynamic changes of cytoplasmic and cortical actin filaments drive various cellular and developmental processes. Although real-time imaging of actin filaments in living cells has been developed, imaging of actin filaments in specific cells of living organisms remains limited, particularly for the analysis of gamete formation and early embryonic development. Here, we report the production of transgenic zebrafish expressing the C-terminus of Moesin, an actin filament-binding protein, fused with green fluorescent protein or red fluorescent protein (GFP/RFP-MoeC), under the control of a cyclin B1 promoter. GFP/RFP-MoeC was expressed maternally, which labels the cortical actin cytoskeleton of blastula-stage cells. High levels of GFP/RFP fluorescence were detected in the adult ovary and testis. In the ovaries, GFP/RFP-MoeC was expressed in oocytes but not in follicle cells, which allows us to clearly visualize the organization of actin filaments in different stages of the oocyte. Using full-grown oocytes, we revealed the dynamic changes of actin columns assembled in the cortical cytoplasm during oocyte maturation. The number of columns slightly decreased in the early period before germinal vesicle breakdown (GVBD) and then significantly decreased at GVBD, followed by recovery after GVBD. Our transgenic fish are useful for analyzing the dynamics of actin filaments in oogenesis and early embryogenesis.
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Affiliation(s)
- Yumiko Nukada
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Mayu Horie
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Akimasa Fukui
- Laboratory of Tissue and Polymer Sciences, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Tomoya Kotani
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Masakane Yamashita
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
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Sharma D, Kinsey WH. PYK2: a calcium-sensitive protein tyrosine kinase activated in response to fertilization of the zebrafish oocyte. Dev Biol 2012; 373:130-40. [PMID: 23084926 DOI: 10.1016/j.ydbio.2012.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 09/22/2012] [Accepted: 10/11/2012] [Indexed: 12/23/2022]
Abstract
Fertilization begins with binding and fusion of a sperm with the oocyte, a process that triggers a high amplitude calcium transient which propagates through the oocyte and stimulates a series of preprogrammed signal transduction events critical for zygote development. Identification of the pathways downstream of this calcium transient remains an important step in understanding the basis of zygote quality. The present study demonstrates that the calcium-calmodulin sensitive protein tyrosine kinase PYK2 is a target of the fertilization-induced calcium transient in the zebrafish oocyte and that it plays an important role in actin-mediated events critical for sperm incorporation. At fertilization, PYK2 was activated initially at the site of sperm-oocyte interaction and was closely associated with actin filaments forming the fertilization cone. Later PYK2 activation was evident throughout the entire oocyte cortex, however activation was most intense over the animal hemisphere. Fertilization-induced PYK2 activation could be blocked by suppressing calcium transients in the ooplasm via injection of BAPTA as a calcium chelator. PYK2 activation could be artificially induced in unfertilized oocytes by injection of IP3 at concentrations sufficient to induce calcium release. Functionally, suppression of PYK2 activity by chemical inhibition or by injection of a dominant-negative construct encoding the N-terminal ERM domain of PKY2 inhibited formation of an organized fertilization cone and reduced the frequency of successful sperm incorporation. Together, the above findings support a model in which PYK2 responds to the fertilization-induced calcium transient by promoting reorganization of the cortical actin cytoskeleton to form the fertilization cone.
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Affiliation(s)
- Dipika Sharma
- Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Fuentes R, Fernández J. Ooplasmic segregation in the zebrafish zygote and early embryo: Pattern of ooplasmic movements and transport pathways. Dev Dyn 2010; 239:2172-89. [DOI: 10.1002/dvdy.22349] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Lindeman RE, Pelegri F. Vertebrate maternal-effect genes: Insights into fertilization, early cleavage divisions, and germ cell determinant localization from studies in the zebrafish. Mol Reprod Dev 2010; 77:299-313. [PMID: 19908256 PMCID: PMC4276564 DOI: 10.1002/mrd.21128] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the earliest stages of animal development prior to the commencement of zygotic transcription, all critical cellular processes are carried out by maternally-provided molecular products accumulated in the egg during oogenesis. Disruption of these maternal products can lead to defective embryogenesis. In this review, we focus on maternal genes with roles in the fundamental processes of fertilization, cell division, centrosome regulation, and germ cell development with emphasis on findings from the zebrafish, as this is a unique and valuable model system for vertebrate reproduction.
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Affiliation(s)
- Robin E. Lindeman
- Laboratory of Genetics, University of Wisconsin – Madison, Madison, Wisconsin
| | - Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin – Madison, Madison, Wisconsin
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Impact of marine drugs on cytoskeleton-mediated reproductive events. Mar Drugs 2010; 8:881-915. [PMID: 20479959 PMCID: PMC2866467 DOI: 10.3390/md8040881] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/02/2010] [Accepted: 03/23/2010] [Indexed: 12/30/2022] Open
Abstract
Marine organisms represent an important source of novel bioactive compounds, often showing unique modes of action. Such drugs may be useful tools to study complex processes such as reproduction; which is characterized by many crucial steps that start at gamete maturation and activation and virtually end at the first developmental stages. During these processes cytoskeletal elements such as microfilaments and microtubules play a key-role. In this review we describe: (i) the involvement of such structures in both cellular and in vitro processes; (ii) the toxins that target the cytoskeletal elements and dynamics; (iii) the main steps of reproduction and the marine drugs that interfere with these cytoskeleton-mediated processes. We show that marine drugs, acting on microfilaments and microtubules, exert a wide range of impacts on reproductive events including sperm maturation and motility, oocyte maturation, fertilization, and early embryo development.
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Sun QY, Schatten H. Regulation of dynamic events by microfilaments during oocyte maturation and fertilization. Reproduction 2006; 131:193-205. [PMID: 16452714 DOI: 10.1530/rep.1.00847] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Actin filaments (microfilaments) regulate various dynamic events during oocyte meiotic maturation and fertilization. In most species, microfilaments are not required for germinal vesicle breakdown and meiotic spindle formation, but they mediate peripheral nucleus (chromosome) migration, cortical spindle anchorage, homologous chromosome separation, cortex development/maintenance, polarity establishment, and first polar body emission during oocyte maturation. Peripheral cortical granule migration is controlled by microfilaments, while mitochondria movement is mediated by microtubules. During fertilization, microfilaments are involved in sperm incorporation, spindle rotation (mouse), cortical granule exocytosis, second polar body emission and cleavage ring formation, but are not required for pronuclear apposition (except for the mouse). Many of the events are driven by the dynamic interactions between myosin and actin filaments whose polymerization is regulated by RhoA, Cdc42, Arp2/3 and other signaling molecules. Studies have also shown that oocyte cortex organization and polarity formation mediated by actin filaments are regulated by mitogen-activated protein kinase, myosin light-chain kinase, protein kinase C and its substrate p-MARKS as well as PAR proteins. The completion of several dynamic events, including homologous chromosome separation, spindle anchorage, spindle rotation, vesicle organelle transport and pronuclear apposition (mouse), requires interactions between microfilaments and microtubules, but determination of how the two systems of the cytoskeleton precisely cross-link, and which proteins link microfilaments to microtubules to perform functions in eggs, requires further studies. Finally, the meaning of microfilament-mediated oocyte polarity versus embryo polarity and embryo development in different species (Drosophila, Xenopus and mouse) is discussed.
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Affiliation(s)
- Qing-Yuan Sun
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China
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Fernández J, Valladares M, Fuentes R, Ubilla A. Reorganization of cytoplasm in the zebrafish oocyte and egg during early steps of ooplasmic segregation. Dev Dyn 2006; 235:656-71. [PMID: 16425221 DOI: 10.1002/dvdy.20682] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The aim of this work is to determine when and how ooplasmic segregation is initiated in the zebrafish egg. To this end, the organization of the ooplasm and vitelloplasm were examined in oocytes and eggs shortly after activation. Ooplasmic segregation, initiated in the stage V oocyte, led to the formation of ooplasmic domains rich in organelles, and ribonucleoproteins. A linear array of closely arranged peripheral yolk globules separated an outer domain of ectoplasm from an inner domain of interconnected endoplasmic lacunae. The structure of this yolk array and the distribution of microinjected labeled tracers suggests that it may provide a barrier limiting ooplasm transit. Loosely arranged yolk globules at the animal hemisphere allow wide connections between the endoplasm and a preblastodisc domain. Activation caused further segregation of ooplasm, reorganization of endoplasmic lacunae, and blastodisc growth. The presence of an endoplasmic cytoskeleton suggests that these changes may be driven by microtubules and microfilaments.
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Affiliation(s)
- Juan Fernández
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile.
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12
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Sharma D, Kinsey WH. Fertilization triggers localized activation of Src-family protein kinases in the zebrafish egg. Dev Biol 2006; 295:604-14. [PMID: 16698010 PMCID: PMC4324460 DOI: 10.1016/j.ydbio.2006.03.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Revised: 03/28/2006] [Accepted: 03/29/2006] [Indexed: 11/28/2022]
Abstract
Fertilization triggers activation of Src-family kinases in eggs of various species including marine invertebrates and lower vertebrates. While immunofluorescence studies have localized Src-family kinases to the plasma membrane or cortical cytoplasm, no information is available regarding the extent to which these kinases are activated in different regions of the zygote. The objective of the present study was to detect the subcellular distribution of activated Src-family kinases in the fertilized zebrafish egg. An antibody specific for the active, non-phosphorylated form of Src-family PTKs was used to detect these activated kinases by immunofluorescence. The results demonstrate that Fyn, and possibly other Src family members are activated by dephosphorylation of the C-terminal tyrosine at fertilization. The activated Src-family kinases are asymmetrically distributed around the egg cortex with an area of higher kinase activity localized adjacent to the micropyle near the presumptive animal pole. Fertilization initially caused elevation of kinase activity in the cytoplasm underlying the micropyle, but this quickly spread to involve the entire zygote cortex. Later, during egg activation, formation of the blastodisc involved concentration of active Src-family kinase in the blastodisc cortex. As cytokinesis began, activated Src-family kinases were no longer limited to the cortex, but became more evenly distributed in the clear apical cytoplasm of the blastomeres. The results demonstrate that the cortex of the zebrafish egg is functionally differentiated and that fertilization triggers localized activation of Src-family kinases at the point of sperm entry, which subsequently progresses through the entire egg cortex.
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Affiliation(s)
| | - William H. Kinsey
- To whom correspondence should be addressed: Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160., Tel.: 913-588-2721; Fax: 913-588-2710.
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13
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Theusch EV, Brown KJ, Pelegri F. Separate pathways of RNA recruitment lead to the compartmentalization of the zebrafish germ plasm. Dev Biol 2006; 292:129-41. [PMID: 16457796 DOI: 10.1016/j.ydbio.2005.12.045] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 12/19/2005] [Accepted: 12/21/2005] [Indexed: 11/25/2022]
Abstract
The maternal RNAs vasa, dead end, nanos1, and daz-like all become localized to the peripheral ends of the first and second cleavage furrows, where they form part of the zebrafish germ plasm. We show that aggregates of a first class of germ plasm components, which include dead end, nanos1, and vasa RNAs, are initially present in a wide cortical band at the animal pole. Aggregates containing these three RNAs appear to be associated with f-actin, which during the first cell cycle undergoes a microtubule-dependent movement towards the periphery as well as circumferential alignment. These cytoskeletal rearrangements lead to the further aggregation of particles containing these RNAs and their concomitant recruitment to the forming furrow. Aggregates containing a second class of germ plasm RNA components, which include the transcript for daz-like, translocate along the plane of the cortex towards the animal pole, where they are recruited to the germ plasm. After recruitment to the furrow, these two classes of RNAs occupy overlapping yet distinct regions of the germ plasm, and this arrangement is maintained during the early cleavage stages. Our observations suggest that separate pathways of RNA recruitment facilitate the compartmentalization of the zebrafish germ plasm.
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Affiliation(s)
- Elizabeth V Theusch
- Laboratory of Genetics, University of Wisconsin-Madison, 425-G Henry Mall, Madison, WI 53706, USA
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14
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Pelegri F, Dekens MPS, Schulte-Merker S, Maischein HM, Weiler C, Nüsslein-Volhard C. Identification of recessive maternal-effect mutations in the zebrafish using a gynogenesis-based method. Dev Dyn 2004; 231:324-35. [PMID: 15366009 DOI: 10.1002/dvdy.20145] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In animal species, early developmental processes are driven by maternally derived factors. Here, we describe a forward genetics approach to identify recessive mutations in genes encoding such maternal factors in the zebrafish. We used a gynogenesis-based approach to identify 14 recessive maternal-effect mutations. Homozygosity for these mutations in adult females leads to the inviability of their offspring. Confocal microscopy of embryos labeled with a DNA dye and a membrane marker allowed us to further analyze mutant embryos for defects in nuclear and cellular divisions. The mutations result in a range of defects in early developmental processes, including egg activation, early nuclear events, mitosis, cytokinesis, axial patterning, and gastrulation. Our effort constitutes a systematic attempt to identify maternal-effect genes in a vertebrate species. The sample of mutations that we have identified reflects the diversity of maternally driven functions in early development and underscores the importance of maternal factors in this process.
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Affiliation(s)
- Francisco Pelegri
- Max-Plank Institut für Entwicklungsbiologie, Abteilung Genetik, Tübingen, Germany.
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Abstract
All processes that occur before the activation of the zygotic genome at the midblastula transition are driven by maternal products, which are produced during oogenesis and stored in the mature oocyte. Upon egg activation and fertilization, these maternal factors initiate developmental cascades that carry out the embryonic developmental program. Even after the initiation of zygotic gene expression, perduring maternal products continue performing essential functions, either together with other maternal factors or through interactions with newly expressed zygotic products. Advances in zebrafish research have placed this organism in a unique position to contribute to a detailed understanding of the role of maternal factors in early vertebrate development. This review summarizes our knowledge on the processes involved in the production and redistribution of maternal factors during zebrafish oogenesis and early development, as well as our understanding of the function of these factors in axis formation, germ layer and germ cell specification, and other early embryonic processes.
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Affiliation(s)
- Francisco Pelegri
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, USA.
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Poleo GA, Denniston RS, Reggio BC, Godke RA, Tiersch TR. Fertilization of eggs of zebrafish, Danio rerio, by intracytoplasmic sperm injection. Biol Reprod 2001; 65:961-6. [PMID: 11514364 DOI: 10.1095/biolreprod65.3.961] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
To evaluate the potential for fertilization by sperm injection into fish eggs, sperm from zebrafish, Danio rerio, were microinjected directly into egg cytoplasm of two different zebrafish lines. To evaluate physiological changes of gametes on the possible performance of intracytoplasmic sperm injection (ICSI), four different combinations of injection conditions were conducted using activated or nonactivated gametes. From a total of 188 zebrafish eggs injected with sperm in all treatments, 31 (16%) developed to blastula, 28 (15%) developed to gastrula, 10 (5%) developed abnormally to larval stages, and another 3 (2%) developed normally and hatched. The highest fertilization rate (blastodisc formation) was achieved by injection of activated spermatozoa into nonactivated eggs (35%). Injections were most effective when performed within the first hour after egg collection. Flow cytometric analysis of the DNA content of the developing ICSI embryos revealed diploidy, and the use of a dominant pigment marker confirmed paternal inheritance. Our study indicates that injection of a single sperm cell into the cytoplasm of zebrafish eggs allows fertilization and subsequent development of normal larvae to hatching and beyond.
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Affiliation(s)
- G A Poleo
- Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
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Sun QY, Lai L, Park KW, Kühholzer B, Prather RS, Schatten H. Dynamic events are differently mediated by microfilaments, microtubules, and mitogen-activated protein kinase during porcine oocyte maturation and fertilization in vitro. Biol Reprod 2001; 64:879-89. [PMID: 11207204 DOI: 10.1095/biolreprod64.3.879] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The role of microfilaments, microtubules, and mitogen-activated protein (MAP) kinase in regulation of several important dynamic events of porcine oocyte maturation and fertilization is described. Fluorescently labeled microfilaments, microtubules, and cortical granules were visualized using either epifluorescence microscopy or laser scanning confocal microscopy. Mitogen-activated protein kinase phosphorylation was revealed by Western immunoblotting. We showed that 1) microfilament disruption did not affect meiosis resumption and metaphase I meiotic apparatus formation but inhibited further cell cycle progression (chromosome separation) even though MAP kinase was phosphorylated; 2) cortical granule (CG) migration was driven by microfilaments (but not microtubules), and once the chromosomes and CGs were localized beneath the oolemma their anchorage to the cortex was independent of either microfilaments or microtubules; 3) neither microfilaments nor microtubules were involved in CG exocytosis during oocyte activation; 4) sperm incorporation was mediated by microfilaments, while pronuclear (PN) syngamy was controlled by microtubules rather than microfilaments; 5) spindle microtubule organization was temporally correlated with MAP kinase phosphorylation, while the extensive microtubule organization in the sperm aster that is required for PN apposition and syngamy occurred in the absence of MAP kinase activation; and 6) MAP kinase phosphorylation did not change either when microtubules were disrupted by nocodazole or when cytoplasmic microtubule asters were induced by taxol. The present study suggests that the role of the cytoskeleton during porcine oocyte maturation is similar to that of rodents, while the mechanisms of fertilization in pig resemble those of lower vertebrates.
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Affiliation(s)
- Q Y Sun
- Department of Veterinary Pathobiology, University of Missouri-Columbia, Columbia, Missouri 65211, USA
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18
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Leung CF, Webb SE, Miller AL. On the mechanism of ooplasmic segregation in single-cell zebrafish embryos. Dev Growth Differ 2000; 42:29-40. [PMID: 10831041 DOI: 10.1046/j.1440-169x.2000.00484.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It has been previously shown that localized elevations of free cytosolic calcium are associated with a morphological contraction in the forming blastodisc and animal hemisphere cortex during ooplasmic segregation in zebrafish zygotes. It was subsequently proposed, in a hypothetical model, that these calcium transients might be linked to the contraction of a cortically located actin microfilament network as a potential driving force for segregation. Here, by labeling single-cell embryos during the major phase of segregation with rhodamine-phalloidin, direct evidence is presented to indicate that the surface contraction was generated by an actin-based cortical network. Furthermore, while zygotes incubated with colchicine underwent normal ooplasmic segregation, those incubated with cytochalasin B did not generate a constriction band or segregate to form a blastodisc. During segregation at the single-cell stage, ooplasm simultaneously moved in two directions: toward the blastodisc within the so-called axial streamers, and toward the vegetal pole in the peripheral ooplasm. The velocities of both axial and peripheral streaming movements are reported. By injection of a fluorescein isothiocyanate (FITC)-labeled 2000 kDa dextran into the peripheral ooplasm it was demonstrated that a portion of it feeds into the bases of the extending streamers, which helps to explain the lack of accumulation of ooplasm at the vegetal pole. These new data were incorporated into the original model to link the bipolar ooplasmic movements with the calcium-modulated, actin-mediated contraction of the animal hemisphere cortex as a means of establishing and driving ooplasmic segregation in zebrafish.
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Affiliation(s)
- C F Leung
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, China
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19
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Pelegri F, Schulte-Merker S. A gynogenesis-based screen for maternal-effect genes in the zebrafish, Danio rerio. Methods Cell Biol 1999; 60:1-20. [PMID: 9891328 DOI: 10.1016/s0091-679x(08)61891-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- F Pelegri
- Max-Planck Institut für Entwicklungsbiologie, Tübingen, Germany
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20
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Affiliation(s)
- J Topczewski
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA
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Abstract
Vertebrate embryos, despite quite diverse early morphologies, appear to employ similar cellular strategies and conserved biochemical pathways in their development (Eyal-Giladi, 1997). In the past decade, a small tropical teleost, zebrafish (Danio rerio), became an important model system in which to study development (Streisinger et al., 1981). By combining embryology with molecular and classical genetic methods, our understanding of early inductive and morphogenetic events during vertebrate embryogenesis significantly advanced. In zebrafish, dorsal-ventral polarity is established during early cleavage and is dependent on microtubular transport of determinants from the vegetal pole to the blastomeres positioned on top of the yolk cell. The syncytium forming from these marginal blastomeres in the early blastula exhibits dorsal-ventral asymmetry with beta-catenin localized to the nuclei on the presumptive dorsal side of the syncytium. The yolk cell is a source of signals that induce and pattern overlying blastoderm. Therefore, the dorsal yolk syncytial layer is equivalent to the Nieuwkoop center of the amphibian embryo. The embryonic shield, a thickening of the dorsal blastoderm margin, exhibits properties similar to the amphibian Spemann organizer. However, certain inductive and patterning signals from the organizer might be produced before the shield forms or might originate outside of the shield. Similar to the amphibian embryo, the key patterning functions of the fish dorsal organizer (i.e., dorsalization of mesoderm, ectoderm, and coordination of gastrulation movements) are performed by secreted molecules that antagonize the ventralizing activity of the swil (zbmp-2) and zbmp-4 gene products expressed on the ventral side of the embryo. These functions of the dorsal organizer require the activity of the chordino gene (a zebrafish homologue of chordin), bozozok, mercedes and ogon loci.
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Affiliation(s)
- L Solnica-Krezel
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37232, USA
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22
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Abstract
In order to understand the mechanisms of fertilization in the teleost, the movements of the egg cortex, cytoplasmic inclusions and pronuclei were observed in detail in fertilized medaka Oryzias latipes eggs. The first cortical contraction occurred toward the animal pole region following the onset of exocytosis of cortical alveoli. The cortical contraction caused movement of oil droplets toward the animal pole where the germinal vesicle had broken down during oocyte maturation. The movement of oil droplets toward the animal pole region was frequently twisted in the right or left direction. The direction of the twisting movement has been correlated with the unilateral bending of non-attaching filaments on the chorion. The female pronucleus, which approached the male pronucleus from the vicinity of the second polar body, took a course to the right, left or straight along the s-p axis connecting the male pronucleus and the second polar body. The course of approach by the female pronucleus correlated with the bending direction of the non-attaching filaments that had been determined by rotation of the oocyte around the animal-vegetal axis during oogenesis. The first cleavage furrow also very frequently coincided with the axis. These observations suggest that dynamic responses of medaka eggs from fertilization to the first cleavage reflect the architecture dynamically constructed during oogenesis.
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Affiliation(s)
- T Iwamatsu
- Department of Biology, Aichi University of Education, Kariya, Japan
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23
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Bally-Cuif L, Schatz WJ, Ho RK. Characterization of the zebrafish Orb/CPEB-related RNA binding protein and localization of maternal components in the zebrafish oocyte. Mech Dev 1998; 77:31-47. [PMID: 9784598 DOI: 10.1016/s0925-4773(98)00109-9] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The animal/vegetal axis of the zebrafish egg is established during oogenesis, but the molecular factors responsible for its specification are unknown. As a first step towards the identification of such factors, we present here the first demonstration of asymmetrically distributed maternal mRNAs in the zebrafish oocyte. To date, we have distinguished three classes of mRNAs, characterized by the stage of oocyte maturation at which they concentrate to the future animal pole. We have further characterized one of these mRNAs, zorba, which encodes a homologue of the Drosophila Orb and Xenopus CPEB RNA-binding proteins. Zorba belongs to the group of earliest mRNAs to localize at the animal pole, where it becomes restricted to a tight subcortical crescent at stage III of oogenesis. We show that this localization is independent of microtubules and microfilaments, and that the distribution of Zorba protein parallels that of its mRNA.
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Affiliation(s)
- L Bally-Cuif
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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24
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Abstract
Through the injection of f-aequorin (a calcium-specific luminescent reporter), and the use of an imaging photon detector, transient localized elevations of free cytosolic calcium in the forming blastodisc (BD) and animal hemisphere cortex were visualized that correlated with ooplasmic segregation. The introduction of an appropriate concentration of the weak (KD = 1.5 micromol/L) calcium buffer 5,5'-dibromo-BAPTA results in the dissipation of these calcium domains, and inhibits cytoplasmic streaming and the subsequent formation of a BD at the animal pole. These inhibitory actions are dependent on the final cytosolic concentration of buffer within the egg: > or = 1.3 mmol/L blocks ooplasmic streaming; < 1.3 mmol/L eggs segregate normally. Injection of 5,5'-dimethyl-BAPTA (KD = 0.15 micromol/L) to a final concentration of 1.5 mmol/L as a control has no effect on ooplasmic streaming. These results suggest that localized domains of elevated free cytosolic calcium are essential for ooplasmic segregation in zebrafish. Furthermore, a hypothetical model is presented linking these calcium transients to the contraction of a cortically located actin microfilament network as a possible mechanism providing the driving force for segregation.
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Affiliation(s)
- C F Leung
- Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay
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25
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Wilson NF, Foglesong MJ, Snell WJ. The Chlamydomonas mating type plus fertilization tubule, a prototypic cell fusion organelle: isolation, characterization, and in vitro adhesion to mating type minus gametes. J Cell Biol 1997; 137:1537-53. [PMID: 9199169 PMCID: PMC2137821 DOI: 10.1083/jcb.137.7.1537] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In the biflagellated alga Chlamydomonas, adhesion and fusion of the plasma membranes of gametes during fertilization occurs via an actin-filled, microvillus-like cell protrusion. Formation of this approximately 3-microm-long fusion organelle, the Chlamydomonas fertilization tubule, is induced in mating type plus (mt+) gametes during flagellar adhesion with mating type minus (mt-) gametes. Subsequent adhesion between the tip of the mt+ fertilization tubule and the apex of a mating structure on mt- gametes is followed rapidly by fusion of the plasma membranes and zygote formation. In this report, we describe the isolation and characterization of fertilization tubules from mt+ gametes activated for cell fusion. Fertilization tubules were detached by homogenization of activated mt+ gametes in an EGTA-containing buffer and purified by differential centrifugation followed by fractionation on sucrose and Percoll gradients. As determined by fluorescence microscopy of samples stained with a fluorescent probe for filamentous actin, the method yielded 2-3 x 10(6) fertilization tubules/microg protein, representing up to a 360-fold enrichment of these organelles. Examination by negative stain electron microscopy demonstrated that the purified fertilization tubules were morphologically indistinguishable from fertilization tubules on intact, activated mt+ gametes, retaining both the extracellular fringe and the internal array of actin filaments. Several proteins, including actin as well as two surface proteins identified by biotinylation studies, copurified with the fertilization tubules. Most importantly, the isolated mt+ fertilization tubules bound to the apical ends of activated mt- gametes between the two flagella, the site of the mt- mating structure; a single fertilization tubule bound per cell, binding was specific for gametes, and fertilization tubules isolated from trypsin-treated, activated mt+ gametes did not bind to activated mt- gametes.
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Affiliation(s)
- N F Wilson
- Department of Cell Biology and Neuroscience, The University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
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26
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Ohta T, Nashirozawa C. Sperm penetration and transformation of sperm entry site in eggs of the freshwater teleostRhodeus ocellatus ocellatus. J Morphol 1996; 229:191-200. [DOI: 10.1002/(sici)1097-4687(199608)229:2<191::aid-jmor4>3.0.co;2-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Becker KA, Hart NH. The cortical actin cytoskeleton of unactivated zebrafish eggs: spatial organization and distribution of filamentous actin, nonfilamentous actin, and myosin-II. Mol Reprod Dev 1996; 43:536-47. [PMID: 9052946 DOI: 10.1002/(sici)1098-2795(199604)43:4<536::aid-mrd17>3.0.co;2-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Actin and nonmuscle myosin heavy chain (myosin-II) have been identified and localized in the cortex of unfertilized zebrafish eggs using techniques of SDS-polyacrylamide gel electrophoresis, immunoblotting, and fluorescence microscopy. Whole egg mounts, egg fragments, cryosections, and cortical membrane patches probed with rhodamine phalloidin, fluorescent DNase-I, or anti-actin antibody showed the cortical cytoskeleton to contain two domains of actin: filamentous and nonfilamentous. Filamentous actin was restricted to microplicae and the cytoplasmic face of the plasma membrane where it was organized as an extensive meshwork of interconnecting filaments. The cortical cytoplasm deep to the plasma membrane contained cortical granules and sequestered actin in nonfilamentous form. The cytoplasmic surface (membrane?) of cortical granules displayed an enrichment of nonfilamentous actin. An antibody against human platelet myosin was used to detect myosin-II in whole mounts and egg fragments. Myosin-II colocalized with both filamentous and nonfilamentous actin domains of the cortical cytoskeleton. It was not determined if egg myosin was organized into filaments. Similar to nonfilamentous actin, myosin-II appeared to be concentrated over the surface of cortical granules where staining was in the form of patches and punctate foci. The identification of organized and interconnected domains of filamentous actin, nonfilamentous actin, and myosin-II provides insight into possible functions of these proteins before and after fertilization.
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Affiliation(s)
- K A Becker
- Department of Biological Sciences, Nelson Biological Laboratory, Rutgers University, Piscataway, New Jersey 08855-1059, USA
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28
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Hart NH, Fluck RA. Cytoskeleton in teleost eggs and early embryos: contributions to cytoarchitecture and motile events. Curr Top Dev Biol 1996; 31:343-81. [PMID: 8746670 DOI: 10.1016/s0070-2153(08)60233-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- N H Hart
- Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08855, USA
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29
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Solnica-Krezel L, Stemple DL, Driever W. Transparent things: cell fates and cell movements during early embryogenesis of zebrafish. Bioessays 1995; 17:931-9. [PMID: 8526887 DOI: 10.1002/bies.950171106] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Development of an animal embryo involves the coordination of cell divisions, a variety of inductive interactions and extensive cellular rearrangements. One of the biggest challenges in developmental biology is to explain the relationships between these processes and the mechanisms that regulate them. Teleost embryos provide an ideal subject for the study of these issues. Their optical lucidity combined with modern techniques for the marking and observation of individual living cells allow high resolution investigations of specific morphogenetic movements and the construction of detailed fate maps. In this review we describe the patterns of cell divisions, cellular movements and other morphogenetic events during zebrafish early development and discuss how these events relate to the formation of restricted lineages.
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Affiliation(s)
- L Solnica-Krezel
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, USA
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30
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Selman K, Wallace RA, Sarka A, Qi X. Stages of oocyte development in the zebrafish,Brachydanio rerio. J Morphol 1993; 218:203-224. [DOI: 10.1002/jmor.1052180209] [Citation(s) in RCA: 477] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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