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Spradling AC, Niu W, Yin Q, Pathak M, Maurya B. Conservation of oocyte development in germline cysts from Drosophila to mouse. eLife 2022; 11:83230. [PMID: 36445738 PMCID: PMC9708067 DOI: 10.7554/elife.83230] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/17/2022] [Indexed: 11/30/2022] Open
Abstract
Recent studies show that pre-follicular mouse oogenesis takes place in germline cysts, highly conserved groups of oogonial cells connected by intercellular bridges that develop as nurse cells as well as an oocyte. Long studied in Drosophila and insect gametogenesis, female germline cysts acquire cytoskeletal polarity and traffic centrosomes and organelles between nurse cells and the oocyte to form the Balbiani body, a conserved marker of polarity. Mouse oocyte development and nurse cell dumping are supported by dynamic, cell-specific programs of germline gene expression. High levels of perinatal germ cell death in this species primarily result from programmed nurse cell turnover after transfer rather than defective oocyte production. The striking evolutionary conservation of early oogenesis mechanisms between distant animal groups strongly suggests that gametogenesis and early embryonic development in vertebrates and invertebrates share even more in common than currently believed.
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Affiliation(s)
- Allan C Spradling
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Wanbao Niu
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Qi Yin
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Madhulika Pathak
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
| | - Bhawana Maurya
- Carnegie Institution for Science/Howard Hughes Medical Institute, Baltimore, United States
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2
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Qin D, Gao Z, Xiao Y, Zhang X, Ma H, Yu X, Nie X, Fan N, Wang X, Ouyang Y, Sun QY, Yi Z, Li L. The subcortical maternal complex protein Nlrp4f is involved in cytoplasmic lattice formation and organelle distribution. Development 2019; 146:dev.183616. [DOI: 10.1242/dev.183616] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 09/13/2019] [Indexed: 01/09/2023]
Abstract
In mammalian oocytes and embryos, the subcortical maternal complex (SCMC) and cytoplasmic lattices (CPLs) are two closely related structures. Their detailed compositions and functions remain largely unclear. Here, we characterized Nlrp4f as a novel component associated with the SCMC and CPLs. Disruption of maternal Nlrp4f leads to decreased fecundity and delayed preimplantation development in the mouse. Lack of Nlrp4f affects organelle distribution in mouse oocytes and early embryos. Depletion of Nlrp4f disrupts CPL formation but does not affect the interactions of other SCMC proteins. Interestingly, the loss of Filia or Tle6, two other SCMC proteins, also disrupts CPL formation in mouse oocytes. Thus, the absence of CPLs and aberrant distribution of organelles in the oocytes disrupted the examined SCMC genes, including previously reported Zbed3, Mater, Floped and Padi6, indicate that the SCMC is required for CPL formation and organelle distribution. Consistent with the SCMC's role in CPL formation, the SCMC forms before CPLs during oogenesis. Together, our results suggest that SCMC protein Nlrp4f is involved in CPL formation and organelle distribution in mouse oocytes.
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Affiliation(s)
- Dandan Qin
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zheng Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Reproductive Medicine Center of the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Yi Xiao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaoxin Zhang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Haixia Ma
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xingjiang Yu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaoqing Nie
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Na Fan
- Key Laboratory of Urban Agriculture (North) of Ministry of Agriculture, College of Biological Science and Engineering, Beijing University of Agriculture, Beijing, 102206, China
| | - Xiaoqing Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yingchun Ouyang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Qing-Yuan Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhaohong Yi
- Key Laboratory of Urban Agriculture (North) of Ministry of Agriculture, College of Biological Science and Engineering, Beijing University of Agriculture, Beijing, 102206, China
| | - Lei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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3
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Schulz LC, Roberts RM. Dynamic changes in leptin distribution in the progression from ovum to blastocyst of the pre-implantation mouse embryo. Reproduction 2011; 141:767-77. [PMID: 21444625 DOI: 10.1530/rep-10-0532] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The hormone leptin, which is primarily produced by adipose tissue, is a critical permissive factor for multiple reproductive events in the mouse, including implantation. In the CD1 strain, maternally derived leptin from the oocyte becomes differentially distributed among the blastomeres of pre-implantation embryos to create a polarized pattern, a feature consistent with a model of development in which blastomeres are biased toward a particular fate as early as the two-cell stage. In this study, we have confirmed that embryonic leptin is of maternal origin and re-examined leptin distribution in two distinct strains in which embryos were derived after either normal ovulation or superovulation. A polarized pattern of leptin distribution was found in the majority of both CD1 and CF1 embryos (79.1 and 76.9% respectively) collected following superovulation but was reduced, particularly in CF1 embryos (29.8%; P<0.0001), after natural ovulation. The difference in leptin asymmetries in the CF1 strain arose between ovulation and the first cleavage division and was not affected by removal of the zona pellucida. The presence or absence of leptin polarization was not linked to differences in the ability of embryos to normally develop to blastocyst. In the early blastocyst, leptin was confined subcortically to trophectoderm, but on blastocoel expansion, it was lost from the cells. Throughout development, leptin co-localized with LRP2, a multi-ligand transport protein, and its patterning resembled that noted for the maternal-effect proteins OOEP, NLRP5, and PADI6, suggesting that it is a component of the subcortical maternal complex with as yet unknown significance in pre-implantation development.
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Affiliation(s)
- Laura C Schulz
- Department of Obstetrics, Gynecology and Women's Health, N625A Health Sciences Center, 1 Hospital Drive, Columbia, Missouri 65212, USA.
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4
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Tashiro F, Kanai-Azuma M, Miyazaki S, Kato M, Tanaka T, Toyoda S, Yamato E, Kawakami H, Miyazaki T, Miyazaki JI. Maternal-effect gene Ces5/Ooep/Moep19/Floped is essential for oocyte cytoplasmic lattice formation and embryonic development at the maternal-zygotic stage transition. Genes Cells 2010; 15:813-28. [DOI: 10.1111/j.1365-2443.2010.01420.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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5
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Koeneman BA, Zhang Y, Westerhoff P, Chen Y, Crittenden JC, Capco DG. Toxicity and cellular responses of intestinal cells exposed to titanium dioxide. Cell Biol Toxicol 2009; 26:225-38. [PMID: 19618281 DOI: 10.1007/s10565-009-9132-z] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 06/30/2009] [Indexed: 12/20/2022]
Abstract
The increasing use of nanomaterials in healthcare and industrial products heightens the possibility of their ingestion by humans, other mammals, and fish. While toxicity of many nanomaterials has recently been studied, reports of non-lethal effects of nanomaterials remain ill-defined. This study investigates possible pathways by which nanoparticles, titanium dioxide (TiO(2)), could cross the epithelium layer by employing both toxicity and mechanistic studies. This study provides evidence that at 10 microg/mL and above, TiO(2) nanoparticles cross the epithelial lining of the intestinal model by transcytosis, albeit at low levels. TiO(2) was able to penetrate into and through the cells without disrupting junctional complexes, as measured by gamma-catenin. To monitor the epithelial integrity, transepithelial electrical resistance (TEER) was employed and determined low concentrations (10 or 100 microg/mL) of TiO(2) do not disrupt epithelial integrity. Live/dead analysis results did not show cell death after exposure to TiO(2). In addition, at 10 microg/mL (and above) TiO(2) nanoparticles begin alteration of both microvillar organization on the apical surface of the epithelium as well as induce a rise in intracellular-free calcium. The latter is a mechanism cells use to respond to extracellular stimuli and may be linked to the alteration of the apical microvilli. Although TiO(2) does not show cell death, the implication of other, non-lethal, effects could lead to undesired outcomes (i.e., disease, malnutrition, shortened life span, etc.).
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Affiliation(s)
- Brian A Koeneman
- Cellular and Molecular Biosciences Faculty, School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA
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6
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Gallicano GI, Foshay K, Pengetnze Y, Zhou X. Dynamics and unexpected localization of the plakin binding protein, kazrin, in mouse eggs and early embryos. Dev Dyn 2005; 234:201-14. [PMID: 16086310 DOI: 10.1002/dvdy.20519] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The cell uses the cytoskeleton in virtually every aspect of cell survival and function. One primary function of the cytoskeleton is to connect to and stabilize intercellular junctions. To accomplish this task, microtubules, actin filaments, and intermediate filaments utilize cytolinker proteins, which physically bind the cytoskeletal filament to the core proteins of the adhesion junction. The plakin family of linker proteins have been in the spotlight recently as critical components for embryo survival and, when mutated, the cause of diseases such as muscular dystrophy and cardiomyopathies. Here, we reveal the dynamics of a recently discovered plakin binding protein, kazrin (kaz), during early mouse development. Kaz was originally found in adult tissues, primarily epidermis, linking periplakin to the plasma membrane and colocalizing with desmoplakin in desmosomes. Using reverse transcriptase-polymerase chain reaction, Western blots, and confocal microscopy, we found kaz in unfertilized eggs associated with the spindle apparatus and cytoskeletal sheets. As quickly as 5 min after egg activation, kaz relocates to a diffuse peri-spindle position, followed 20-30 min later by clear localization to the presumptive cytokinetic ring. Before the blastocyst stage of development, kaz associates with the nuclear matrix in a cell cycle-dependent manner, and also associates with the cytoplasmic actin cytoskeleton. After blastocyst formation, kaz localization and potential function(s) become highly complex as it is found associating with cell-cell junctions, the cytoskeleton, and nucleus. Postimplantation stages of development reveal that kaz retains a multifunctional, tissue-specific role as it is detected at diverse locations in various embryonic tissue types.
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Affiliation(s)
- G Ian Gallicano
- Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007, USA.
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7
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Hwang KC, Lee HY, Cui XS, Kim JH, Kim NH. Identification of maternal mRNAs in porcine parthenotes at the 2-cell stage: a comparison with the blastocyst stage. Mol Reprod Dev 2005; 70:314-23. [PMID: 15625692 DOI: 10.1002/mrd.20204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Successful embryonic development is dependent on the temporal and stage-specific expression of appropriate genes. Currently, information on specific gene expression during early cleavage-stage embryos before zygotic gene activation (ZGA) is limited. In the present study, we compare gene expression between porcine 2-cell and blastocyst stage parthenotes to identify genes that are specifically or predominantly expressed by employing annealing control primer (ACP)-based GeneFishing PCR. Using 60 ACPs, we identified and sequenced nine differentially expressed genes (DEGs). A BLAST search revealed that cloned genes or ESTs (GDI-2, MTMR3, MKLN1, NUP88, ePAD, CIRHIM, UPF3B, ITGA2, and CGI-140) had significant sequence similarities with known genes (78-95%) of other species in the GenBank/EMBL database. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) data disclosed that these genes were regulated upstream in metaphase II (MII) oocyte, 1-cell, and 2-cell stage embryos during early pre-implantation. Similarly, upregulation was observed in MII mouse oocytes and 1-cell stage embryos before ZGA, suggesting that these nine differentially expressed orthologous genes play important roles during early cleavage before ZGA. Further analysis of the differentially expressed genes identified in this report should provide the basis for research on early cleavage and activation of the embryonic genome.
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Affiliation(s)
- Kyu-Chan Hwang
- Department of Animal Sciences, Chungbuk National University, Gaesin-dong, Cheongju, Chungbuk 361-763, South Korea
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8
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Wells D, Bermudez MG, Steuerwald N, Thornhill AR, Walker DL, Malter H, Delhanty JDA, Cohen J. Expression of genes regulating chromosome segregation, the cell cycle and apoptosis during human preimplantation development. Hum Reprod 2005; 20:1339-48. [PMID: 15705620 DOI: 10.1093/humrep/deh778] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Appropriate gene expression is vital for the regulation of developmental processes. Despite this fact there is a remarkable paucity of information concerning gene activity during preimplantation development. METHODS We employed reverse transcription and real-time fluorescent PCR to quantify the expression of nine genes (BRCA1, BRCA2, ATM, TP53, RB1, MAD2, BUB1, APC and beta-actin) in oocytes and embryos. A full characterization of all genes was achieved in 42 embryos and four oocytes. The genes analysed have a variety of important cellular functions. RESULTS Oocytes displayed relatively high levels of mRNA transcripts, while 2-3-cell embryos were seen to contain very little mRNA from any of the genes examined. Recovery of expression levels was not seen until the 4-cell stage or later, with the presumptive activation of the embryonic genome. Some genes displayed sharp increases in expression in embryos composed of 4-8 cells, but, for most, maximum expression was not achieved until the blastocyst stage. CONCLUSIONS Our data show that it is possible to define characteristic gene expression profiles for each stage of human preimplantation development. The identification of genes active at defined preimplantation phases may provide clues to the cellular pathways utilized at specific stages of development. Expression of genes that function in DNA repair pathways indicate that DNA damage may be common at the cleavage stage. We suggest that specific patterns of gene expression may be indicative of embryo implantation potential.
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Affiliation(s)
- D Wells
- Department of Obstetrics & Gynecology, Yale University Medical School, New Haven, CT 06520, USA.
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9
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Wright PW, Bolling LC, Calvert ME, Sarmento OF, Berkeley EV, Shea MC, Hao Z, Jayes FC, Bush LA, Shetty J, Shore AN, Reddi PP, Tung KS, Samy E, Allietta MM, Sherman NE, Herr JC, Coonrod SA. ePAD, an oocyte and early embryo-abundant peptidylarginine deiminase-like protein that localizes to egg cytoplasmic sheets. Dev Biol 2003; 256:73-88. [PMID: 12654293 DOI: 10.1016/s0012-1606(02)00126-4] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selected for its high relative abundance, a protein spot of MW approximately 75 kDa, pI 5.5 was cored from a Coomassie-stained two-dimensional gel of proteins from 2850 zona-free metaphase II mouse eggs and analyzed by tandem mass spectrometry (TMS), and novel microsequences were identified that indicated a previously uncharacterized egg protein. A 2.4-kb cDNA was then amplified from a mouse ovarian adapter-ligated cDNA library by RACE-PCR, and a unique 2043-bp open reading frame was defined encoding a 681-amino-acid protein. Comparison of the deduced amino acid sequence with the nonredundant database demonstrated that the protein was approximately 40% identical to the calcium-dependent peptidylarginine deiminase (PAD) enzyme family. Northern blotting, RT-PCR, and in situ hybridization analyses indicated that the protein was abundantly expressed in the ovary, weakly expressed in the testis, and absent from other tissues. Based on the homology with PADs and its oocyte-abundant expression pattern, the protein was designated ePAD, for egg and embryo-abundant peptidylarginine deiminase-like protein. Anti-recombinant ePAD monospecific antibodies localized the molecule to the cytoplasm of oocytes in primordial, primary, secondary, and Graafian follicles in ovarian sections, while no other ovarian cell type was stained. ePAD was also expressed in the immature oocyte, mature egg, and through the blastocyst stage of embryonic development, where expression levels began to decrease. Immunoelectron microscopy localized ePAD to egg cytoplasmic sheets, a unique keratin-containing intermediate filament structure found only in mammalian eggs and in early embryos, and known to undergo reorganization at critical stages of development. Previous reports that PAD-mediated deimination of epithelial cell keratin results in cytoskeletal remodeling suggest a possible role for ePAD in cytoskeletal reorganization in the egg and early embryo.
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Affiliation(s)
- Paul W Wright
- Department of Cell Biology and Center for Research in Contraceptive and Reproductive Health, University of Virginia, Charlottesville, VA 22908, USA
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10
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Gardner RL. The initial phase of embryonic patterning in mammals. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 203:233-90. [PMID: 11131518 DOI: 10.1016/s0074-7696(01)03009-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Although specification of the antero-posterior axis is a critical intial step in development of the fetus, it is not known either how, or at what stage in development, this process begins. Such information is vital for understanding not only normal development in mammals but also monozygotic twinning, which, at least in man, is associated with a significantly increased incidence of birth defects. According to recent studies in the mouse, specification of the fetal anteroposterior axis begins well before gastrulation, and probably even before the conceptus implants. Moreover, evidence is accruing that the origin of relevant asymmetries depends on information that is already present in the zygote before it embarks on cleavage. Hence, early development in mammals does not differ as markedly from that in other animals as has generally been assumed. Consequently, at present, the possibility of adverse effects of techniques used to assist human reproduction cannot be disregarded.
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11
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Capco DG. Molecular and biochemical regulation of early mammalian development. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 207:195-235. [PMID: 11352267 DOI: 10.1016/s0074-7696(01)07006-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fertilization initiates a rapid series of changes that restructures the egg into the zygote and initiates the program of early development. These changes in the cell occur while the genetic complement of the egg and sperm are in a highly condensed state and unable to participate in transcription. The egg cytoplasm, formed by the maternal genome, contains the necessary components that mediate the early restructuring of egg into zygote. These changes are mediated by a series of cytoplasmic signal transduction events initiated by the rise in [Ca2+]i caused when the sperm penetrates the egg. The structural changes that the egg undergoes are rapid and result in the extensive remodeling of this specialized cell. Protein kinase C (PKC) and calcium/calmodulin-dependent protein kinase II (CaM KII) are two pivotal signaling agents that mediate several of these rapid modifications in cell structure. Studies indicate the meiotic spindle serves as an architectural element in the egg that acts to colocalize elements from several of the key signaling pathways and may provide a means for these pathways to interact. In mammals, transcription begins earlier than in zygotes from other classes of organisms, starting several hours after fertilization in the male and female pronuclei and continuing in the embryonic nuclei. Studies indicate that nuclei undergo an initial state that is permissive for transcription, and then in Gap 2 of the two-cell embryo, enter a transcriptionally repressive state. These changes have been linked to the times during the cell cycle when the DNA is replicated, and also have been proposed as a requirement for proper initiation of the program of early development.
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Affiliation(s)
- D G Capco
- Department of Biology, Molecular and Cellular Biology Program, Arizona State University, Tempe 85287, USA
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12
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Affiliation(s)
- A S Belmont
- Department of Cell and Structural Biology, University of Illinois, Urbana-Champaign 61801, USA
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13
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Gallicano GI, McGaughey RW, Capco DG. Activation of protein kinase C after fertilization is required for remodeling the mouse egg into the zygote. Mol Reprod Dev 1997; 46:587-601. [PMID: 9094105 DOI: 10.1002/(sici)1098-2795(199704)46:4<587::aid-mrd16>3.0.co;2-t] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fertilization of the mammalian egg initiates numerous biochemical and structural changes which remodel the egg into a single-celled zygote. To date, the most extensively studied phenomenon of fertilization in virtually all species has been the relationship between sperm penetration and the induction of the initial rise in intracellular-free calcium ([Ca2+]i) concentration within the egg. In contrast, relatively few studies have focused on the biochemical events following this rise in calcium, and even fewer studies have directly linked the biochemical events to the structural changes which must ensue for proper development of the embryo. In this study, we exploited recently developed technologies to investigate the action of protein kinase C (PKC), a presumed downstream transducer of the initial rise in [Ca2+]i, during fertilization and artificial activation with calcium ionophore or phorbol 12-myristate 13-acetate (PMA). The newly developed myristoylated PKC pseudosubstrate (myrPKC psi) was used to specifically inhibit PKC, thereby averting the trauma of injecting the egg with nonmyristoylated PKC psi. Following fertilization, eggs which were pretreated with myr-PKC psi were not capable of forming a second polar body and pronuclear formation was significantly inhibited. Spatial and temporal localization of PKC using confocal microscopy to visualize the PKC reporter dye, Rim-1, demonstrated localization of PKC to the lateral aspects of the forming second polar body after fertilization, or after artificial activation with calcium ionophore or PMA. In vivo biochemical analysis of eggs which were fertilized or artificially activated demonstrated that PKC activity rose at the same time (40 min) as the second polar body formed and then subsided over the next 5 hr post activation. From these data, we conclude that PKC plays an integral role in directing the transformation from egg to embryo.
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Affiliation(s)
- G I Gallicano
- University of Chicago, Howard Hughes Medical Institute, IL, USA
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14
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Gallicano GI, Capco DG. Remodeling of the specialized intermediate filament network in mammalian eggs and embryos during development: regulation by protein kinase C and protein kinase M. Curr Top Dev Biol 1996; 31:277-320. [PMID: 8746668 DOI: 10.1016/s0070-2153(08)60231-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The sheets serve as an maternal supply of assembled, cytokeratin, intermediate filaments. They are remodeled at each major developmental transition in mammalian early development, that is fertilization, embryonic compaction, blastocyst formation, and formation of the primitive ectoderm and primitive endoderm during implantation into the uterine wall. Our results indicate that the sheets exist as specialization for placental development as they have a major role in the maintenance of epithelial integrity at the time the embryo is implanting into the uterine wall. They also contribute intermediate filaments to the junctional complexes required for embryonic compaction. Our analyses demonstrate the they are regulated at the time of fertilization by the action of PKC/PKM, a kinase that acts as a cellular chronometer with both temporal and spatial precision that remodels the egg into the zygote.
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Affiliation(s)
- G I Gallicano
- Molecular and Cellular Biology Program, Arizona State University, Tempe 85287, USA
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15
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Schwarz SM, Gallicano GI, McGaughey RW, Capco DG. A role for intermediate filaments in the establishment of the primitive epithelia during mammalian embryogenesis. Mech Dev 1995; 53:305-21. [PMID: 8645598 DOI: 10.1016/0925-4773(95)00440-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Investigations of the cytoskeleton in mammalian eggs and embryos have revealed the existence of an unusual array of crosslinked intermediate filaments composed of cytokeratins 5, 6, 16, and 'Z' that are referred to as cytoskeletal sheets. We have been investigating the function of these cytoskeletal sheets during embryogenesis. In this investigation we report the rapid appearance of extensive arrays of tonofilaments extending across blastomeres and in association with intercellular desmosomal junctions appearing at the time the embryo hatches from its zona pellucida, through the time of implantation of the embryo into the uterine wall. Just prior to the time of gastrulation these tonofilaments disappear. Electron microscopy and immunoconfocal microscopy demonstrate that the tonofilaments are composed of cytokeratins characteristic of the type found earlier in development, that is types 5 and 6; whereas, cytokeratin type 8 which has been shown to be synthesized in blastocysts is localized primarily at perinuclear regions. Cytokeratins 8 and 18 are synthesized to about the same extent as actin at the time the tonofilaments appear whereas the synthesis of cytokeratins 5 and 6 is greatly reduced. Our results suggest that cytokeratins 5 and 6 in the tonofilaments may arise from the stored form of cytokeratins in the cytoskeletal sheets. Consequently, our results suggest that the sheets may serve as a maternal reserve of cytokeratin employed by the embryo at the time of implantation to form extensive arrays of tonofilaments in the embryo that likely provide structural integrity to the embryo as it is subjected to mechanical stress during invasion and implantation into the uterine wall.
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16
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Gallicano GI, Larabell CA, McGaughey RW, Capco DG. Novel cytoskeletal elements in mammalian eggs are composed of a unique arrangement of intermediate filaments. Mech Dev 1994; 45:211-26. [PMID: 8011554 DOI: 10.1016/0925-4773(94)90009-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mammalian eggs and embryos contain a major network of specialized cytoskeletal components known as 'sheets' that have not been identified in any other cell type. Although eggs from at least seven different mammalian species have been shown to contain these cytoskeletal structures, embedment-free electron microscopic analysis of these eggs revealed that two basic forms of cytoskeletal sheets exist, a solid, planar type of sheet typical of hamster and rat eggs and a fibrous sheet typical of mouse, porcine, bovine, canine, and human eggs. In this study we have investigated the structural composition of the fibrous type of sheet in mouse eggs by employing biochemical approaches as well as two forms of ultrastructural analyses including: (1) analysis of thick, resin-embedded specimens using an intermediate voltage electron microscope (IVEM); (2) analysis of replicas from quick-frozen, deep-etched specimens. Our results indicate that the sheets of mouse eggs and preimplantation embryos are composed of cylindrical bundles of 10-11 nm filaments, with each of these filaments held in register by periodically arranged crossbridges spaced 23-25 nm apart. This sheet substructure of filaments and crossbridges is covered by a particulate material which can be removed by non-ionic detergent. Immunoelectron microscopic analysis of mouse eggs demonstrates that sheets bind antibodies to keratin and to a small extent, actin, but do not bind antibodies to vimentin or tubulin. Confirmation that keratin exists in these eggs was obtained by electrophoretic separation and one- and two-dimensional Western blot analysis demonstrating the existence of keratin types 5, 6, 8, 16, and type Z. The low abundancy of keratin type 8 compared to other keratin types explains the difficulties other investigators have had identifying intermediate filaments in mammalian embryos since most investigators have used antibodies directed specifically against keratin type 8 or its pair keratin type 18. Examination of compacted mouse embryos reveals that the filamentous framework of sheets disassembled and established close contact with the basolateral plasma membrane and the nucleus. However, sheets at the apical plasma membrane of blastomeres attach to the membrane but remain intact. Based on our biochemical and ultrastructural data, the fibrous sheets of mouse eggs appear to be cytoskeletal structures comparable to the solid, planar sheets of the Syrian hamster egg and probably serve similar function(s) in eggs and embryos of several mammalian species.
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Affiliation(s)
- G I Gallicano
- Department of Zoology, Arizona State University, Tempe 85287-1501
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17
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Gallicano GI, McGaughey RW, Capco DG. Ontogeny of the cytoskeleton during mammalian oogenesis. Microsc Res Tech 1994; 27:134-44. [PMID: 8123906 DOI: 10.1002/jemt.1070270207] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mammalian oogenesis is a process which requires a variety of changes in the structure and function of the specialized female germ cell. Evidence suggests that the cytoskeleton may mediate several of these structural and functional changes. In this review we evaluate what is known of cytoskeletal function during oogenesis, with emphasis on specialized cytoskeletal features in mammals. Existing investigations suggest that the oocyte, as a highly specialized cell, contains unique cytoskeletal elements which exhibit functions restricted to the process of early development.
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Affiliation(s)
- G I Gallicano
- Department of Zoology, Arizona State University, Tempe 85287-1501
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18
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Huang JC, Mieziewska K, Philp N, van Veen T, Aguirre GD. Diethylene glycol distearate (DGD): a versatile embedding medium for retinal cytochemistry. J Neurosci Methods 1993; 47:227-34. [PMID: 8271821 DOI: 10.1016/0165-0270(93)90085-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Embedment in diethylene glycol distearate (DGD) was shown to be highly desirable and versatile for retinal cytochemical studies, including in situ hybridization, immuno- and lectin cytochemistry. This method allows for preservation of fine tissue detail as well as good reaction sensitivity. It appears to be more suitable than most other methods currently used for light microscopic retinal cytochemistry.
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Affiliation(s)
- J C Huang
- Section of Medical Genetics School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104
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19
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Capco DG, Gallicano GI, McGaughey RW, Downing KH, Larabell CA. Cytoskeletal sheets of mammalian eggs and embryos: a lattice-like network of intermediate filaments. CELL MOTILITY AND THE CYTOSKELETON 1993; 24:85-99. [PMID: 8440027 DOI: 10.1002/cm.970240202] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Mammalian eggs and embryos possess a major cytoskeletal network composed of large planar "sheets" distributed throughout the cytoplasm. Cytoskeletal sheets are found neither in mammalian somatic cells nor in eggs or embryos of non-mammals. In this study, we have investigated the structural composition of the sheets in eggs and embryos of the golden Syrian hamster by (1) analysis of replicas from quick-frozen, deep-etched specimens, (2) analysis of thick, resin-embedded specimens using an intermediate voltage electron microscope (IVEM), (3) laser diffraction of EM images, (4) differential extraction with detergents, and (5) immunocytochemistry. Our results indicate that each sheet is composed of two closely apposed arrays of 10-nm filaments. Each filament within an array is held in register with its neighbor by lateral cross-bridges and the two parallel arrays of filaments are interconnected by periodic cross-bridges about 20 nm in length. Laser diffraction of negatives from IVEM images indicates that each array is composed of fibers that form a square lattice, and the two arrays are positioned in register by cross-bridges forming a single sheet. This lattice forms the skeleton of the sheets which is covered with a tightly packed layer of particulate material. By incubation in media containing different ratios of mixed-micelle detergents, it is possible to remove components sequentially from the sheets and to extract the particulate material. Immunocytochemical localization demonstrates that the sheets bind antibodies to keratin, and to a small extent actin, but do not bind antibodies to vimentin or tubulin. Examination of sheets within embryos at the time of embryonic compaction demonstrates that the sheets begin to fragment and disassemble in regions of blastomeres where desmosomes form, but undergo no structural alterations in interior and basal surfaces of the blastomeres. In regions of blastomere-blastomere contact the sheets fragment and associate with granules resembling keratohyalin granules found in keratinocytes.
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Affiliation(s)
- D G Capco
- Department of Zoology, Arizona State University, Tempe 85287-1501
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20
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Gallicano GI, McGaughey RW, Capco DG. Cytoskeletal sheets appear as universal components of mammalian eggs. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1992; 263:194-203. [PMID: 1500884 DOI: 10.1002/jez.1402630209] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The eggs of two mammalian species have been shown to contain novel cytoskeletal elements, referred to as cytoskeletal sheets, which undergo stage-specific changes in spatial organization at three key developmental transitions, fertilization, compaction, and blastocyst formation. If cytoskeletal sheets have an integral role in these developmental transitions, the sheets should be present in the eggs of other mammals as well. We examined the eggs of four additional species to determine if sheets were present. Our results indicate that sheets were present and they can be categorized into two classes based on their surface appearance. Cytoskeletal sheets in eggs of hamsters and rats have a smooth surface appearance, while eggs from humans, cows, pigs, and mice have a fibrous surface appearance. In addition, we observed that species-specific variations exist in the width of the sheets and in the density of the sheets (i.e., number per micron 2) in the eggs. These species-specific variations may relate to the role of the sheets during early development.
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Affiliation(s)
- G I Gallicano
- Department of Zoology, Arizona State University, Tempe 85287-1501
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21
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Abstract
Oocytes, eggs, and embryos from a diverse array of species have evolved cytoskeletal specializations which allow them to meet the needs of early embryogenesis. While each species studied possesses one or more specializations which are unique, several cytoskeletal features are widely conserved across different animal phyla. These features include highly-developed cortical cytoskeletal domains associated with developmental information, microtubule-mediated pronuclear transport, and rapid intracellular signal-regulated control of cytoskeletal organization.
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Affiliation(s)
- W M Bement
- Department of Zoology, Arizona State University, Tempe 85287-1501
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22
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Capco DG, Bement WM. Analysis of cellular signaling events, the cytoskeleton, and spatial organization of macromolecules during early Xenopus development. Methods Cell Biol 1991; 36:249-70. [PMID: 1811137 DOI: 10.1016/s0091-679x(08)60281-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- D G Capco
- Department of Zoology, Arizona State University, Tempe 85287-1501
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23
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McGaughey RW, Racowsky C, Rider V, Baldwin K, DeMarais AA, Webster SD. Ultrastructural correlates of meiotic maturation in mammalian oocytes. JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE 1990; 16:257-80. [PMID: 2250183 DOI: 10.1002/jemt.1060160402] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Immature mammalian oocytes reside in ovarian follicles with junctionally coupled granulosa cells. When released from a currently undefined meiotic arresting influence, these oocytes resume meiosis to progress from late diplotene (germinal vesicle stage) through the first meiotic division to metaphase II. Oocytes remain at metaphase II until fertilization activates them to complete meiosis. This review summarizes ultrastructural events that occur during meiotic maturation in mammals. Developmental correlates that promise a clearer understanding of regulatory mechanisms operating to control maturation are emphasized. By use of TEM of thin sections, freeze-fracture analysis, and replicated oocyte cortical patches, we demonstrate stage-specific changes in the oocyte nucleus, reorganization of cytoplasmic organelles, correlations between oocyte maturational commitment and the junctional integrity of associated granulosa cells, and definition of the components comprising the oocyte cortical cytoplasm.
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Affiliation(s)
- R W McGaughey
- Department of Zoology, Arizona State University, Tempe 85287
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24
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Webster SD, McGaughey RW. The cortical cytoskeleton and its role in sperm penetration of the mammalian egg. Dev Biol 1990; 142:61-74. [PMID: 2227102 DOI: 10.1016/0012-1606(90)90151-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this study isolated cortical regions of both penetrated and nonpenetrated Syrian hamster eggs were examined in whole mounts and platinum replicas of detergent-extracted cortical patches. Two types of cytoskeletal organization were observed in the egg cortex: Loose networks (LN regions) with integrated localized dense networks (LDN regions). Decoration with heavy meromyosin and labeling with antiactin/protein G gold both indicate that the cortical cytoskeleton consists mainly of a LN of actin microfilaments and several types of nonactin filaments, whereas LDN regions dispersed within the LN were comprised of nonactin filaments. Cortical patches and replicas of eggs incubated with sperm for 10-15 min provide evidence that cortical microfilaments may be intimately associated with penetrating spermatozoa. The results of this investigation provide the first high resolution view of the cortical cytoskeletal domain of a mammalian egg and suggest that actin microfilaments might play a role in sperm penetration of the egg cortex.
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Affiliation(s)
- S D Webster
- Department of Zoology, Arizona State University, Tempe 85287-1501
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25
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Enders AC, Lantz KC, Schlafke S. Differentiation of the inner cell mass of the baboon blastocyst. Anat Rec (Hoboken) 1990; 226:237-48. [PMID: 2301740 DOI: 10.1002/ar.1092260213] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During the blastocyst stage of development in the baboon, the inner cell mass changes from an irregular accumulation of cells within the cavity of the blastocyst to a disk at one side of the blastocyst and finally to a spherical mass of epiblast cells exhibiting a distinct polarity. The cells that will become the primitive endoderm are first seen as flattened but undifferentiated cells on the cavity side of the disk-shaped inner cell mass. After endoderm cells develop their typical cytological characteristics, they extend well beyond the inner cell mass to form parietal endoderm. A basal lamina develops associated with the epiblast cells and mural trophoblast, but not with either parietal or visceral endoderm. Cytological differentiation of inner cell mass cells includes increased numbers of polyribosomes and a change in mitochondria from long, convoluted structures to short, more typical shapes. Evidence that epiblast is polarized is seen by the late zonal blastocyst stage. Apical junctional complexes develop within the center of the epiblast. These junctions presage the development of the potential amniotic cavity. Large vacuoles containing cell debris, some of which contain nuclear fragments, are present at all stages. Extensive cell death occurs during growth of the blastocyst, but the pattern appears to be random and products of cell death are readily phagocytized by adjacent cells.
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Affiliation(s)
- A C Enders
- Department of Human Anatomy, School of Medicine, University of California, Davis 95616
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26
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Kimber SJ. Glycoconjugates and cell surface interactions in pre- and peri-implantation mammalian embryonic development. INTERNATIONAL REVIEW OF CYTOLOGY 1990; 120:53-167. [PMID: 2406215 DOI: 10.1016/s0074-7696(08)61599-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- S J Kimber
- Department of Cell and Structural Biology, School of Biological Sciences, University of Manchester, England
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27
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Follicle cell development is partly independent of germ-line cell differentiation in Drosophila oogenesis. ACTA ACUST UNITED AC 1989; 198:185-190. [DOI: 10.1007/bf00375904] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/1989] [Accepted: 09/04/1989] [Indexed: 10/26/2022]
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28
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Development of cytoskeletal connections between cells of preimplantation mouse embryos. ACTA ACUST UNITED AC 1989; 198:233-241. [PMID: 28305487 DOI: 10.1007/bf00375910] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/1989] [Accepted: 06/21/1989] [Indexed: 10/26/2022]
Abstract
Observations by scanning electron microscopy of mouse cleaving embryos reveal the presence of long microvilli around cell contact regions that often bridge the gap between blastomeres. These microvilli correspond, in detergent-extracted morulae, to strings connecting the cortical cytoskeletons of adjoining cells. They appear about 4 h after compaction in synchronized cultures. Transmission electron microscopy, heavy meromyosin decoration and DNase I digestion show that cytoskeletal connections contain bundles of actin microfilaments. The establishment of cytoskeletal connections does not require immediate protein synthesis, as shown by incubation with cycloheximide. Diverse treatments that interfere with compaction were tested for the development of cytoskeletal connections: culture media with low Ca2+ and/or Mg2+, or EGTA, or α-lactalbumin, do not prevent the establishment of connections, while colchicine delays their appearance and cytochalasin D suppresses it. The relation between cytoskeletal connections, compaction and blastulation is discussed.
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29
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Ojeda JL, Ros MA, Icardo JM. A technique for fluorescence microscopy in semithin sections. STAIN TECHNOLOGY 1989; 64:243-8. [PMID: 2699110 DOI: 10.3109/10520298909107009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We describe here a procedure to improve contrast and resolution in fluorescence microscopy of sectioned tissues. Tissue fragments were fixed in ethanol-glacial acetic acid, embedded in diethylene glycol distearate, and semithin sectioned. This method maintains tissue antigenicity while preserving the structure of cells and tissues. The thinness of the sections eliminates scattered and emitted light from tissue structures outside the plane of focus. The procedure is simple and quick, and works excellently with fluorescein-conjugated lectins and antibodies.
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Affiliation(s)
- J L Ojeda
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Cantabria, Santander, Spain
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30
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Hauptman RJ, Perry BA, Capco DG. A Freeze-Sectioning Method for Preparation of the Detergent-Resistant Cytoskeleton Identifies Stage-Specific Cytoskeleal Proteins and Associated mRNA in Xenopus Oocytes and Embryos. (Cytoskeleton/amphibian/mRNA). Dev Growth Differ 1989. [DOI: 10.1111/j.1440-169x.1989.00157.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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McGaughey RW, Capco DG. Specialized cytoskeletal elements in mammalian eggs: structural and biochemical evidence for their composition. CELL MOTILITY AND THE CYTOSKELETON 1989; 13:104-11. [PMID: 2475261 DOI: 10.1002/cm.970130205] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mammalian eggs and embryos contain an extensive detergent-resistant cytoskeletal network, including many elements which have been referred to as sheets in hamster eggs. In this study we examined the structure of the sheet-like components by using embedment-free sections and freeze-fracture electron microscopy and found that the sheets are composed of both filamentous and particulate components. In addition, exposure to a high salt extraction medium resulted in the disappearance of the sheets at the ultrastructural level. SDS-polyacrylamide gel electrophoresis of the cell fractions revealed four stainable proteins solubilized by the high salt extraction with one of the proteins being greatly enriched. Because these cytoskeletal sheets undergo an extensive reorganization coincident with key events during early development they serve as internal markers for the establishment of polarity and subsequent differentiation of the first embryonic epithelium, the trophectoderm.
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Affiliation(s)
- R W McGaughey
- Department of Zoology, Arizona State University, Tempe 85287-1501
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32
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Valdimarsson G, Huebner E. The development of microtubular arrays in the germ tissue of an insect telotrophic ovary. Tissue Cell 1989; 21:123-38. [PMID: 2672416 DOI: 10.1016/0040-8166(89)90027-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The microtubular arrays characteristic of the trophic core and cords of the adult Rhodnius prolixus ovary develop prior and during the larval--adult transformation. Development of the microtubules was revealed by immunocytochemistry, electron microscopy and polyacrylamide electrophoresis and Western blot analysis. Microtubular arrays were first detected in the trophic cords and presumptive trophic core 6 days before the adult molt. Cord microtubules increase in length and numbers as the trophic cords grow. Three microtubule packed cords have formed by 1 day post molt. The microtubule distribution in the presumptive core is non-uniform. Microtubule packed areas are interspersed with areas devoid of microtubules. The adult core begins forming between 1 day before molt and molting. This early adult core arises from the fusion of the anterior portions of microtubule packed cords. A fully mature adult core is not present by 2 days post molt. The microtubule packing density in the core increases from 2 days before to 2 days post molt. Tubulin increases from 6 days to 1 day before the adult molt.
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Affiliation(s)
- G Valdimarsson
- Department of Zoology, University of Manitoba, Winnipeg, Canada
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33
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Madreperla SA, Adler R. Opposing microtubule- and actin-dependent forces in the development and maintenance of structural polarity in retinal photoreceptors. Dev Biol 1989; 131:149-60. [PMID: 2642427 DOI: 10.1016/s0012-1606(89)80046-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have used embryonic cells grown in vitro to study the roles of microtubules and microfilaments in the development and maintenance of the polarized shape of retinal photoreceptors. After several days in culture, isolated cone photoreceptors displayed a highly elongated, compartmentalized morphology similar to that of photoreceptors in vivo. When treated with the microtubule-depolymerizing agent nocodazole, these elongated photoreceptors became progressively shorter, eventually losing their compartmentalized structure and becoming round. Conversely, treatment with the actin-depolymerizing agent cytochalasin D caused the elongated photoreceptors to lengthen even further. Computer-assisted, quantitative analysis showed that responses of individual cells to both nocodazole and Cytochalasin D were concentration-dependent, graded, and reversible. Immunocytochemical studies suggested the presence of longitudinally oriented actin filaments and microtubules in these photoreceptors, prominent in the region that undergoes the most pronounced length changes in response to cytoskeletal inhibitors. Prior to becoming elongated, photoreceptor precursors could be accurately identified in early retinal cultures. These round cells undergo a stereotyped sequence of morphogenetic transformations during in vitro development, including elongation and compartmentalization of the cell body as well as extension of a single neurite. Treatment with either cytochalasin D or nocodazole completely blocked morphogenesis. In addition, cytochalasin D caused the development of an abnormal, elongated cell process, which formed by a microtubule-dependent mechanism. These nocodazole and cytochalasin D effects also were reversible. Taken together, these data indicate that the complex developmental transformations leading to photoreceptor polarization occur in the absence of intercellular contacts, and are predominantly controlled by intracellular cytoskeletal forces. They suggest the existence of continuously active, oppositely directed, microtubule- and actin-dependent forces, the balance of which is a determining factor in the development as well as the maintenance of the elongated, compartmentalized organization of photoreceptor cells.
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Affiliation(s)
- S A Madreperla
- Retinal Degenerations Research Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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34
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Perry BA, Capco DG. Spatial reorganization of actin, tubulin and histone mRNAs during meiotic maturation and fertilization in Xenopus oocytes. CELL DIFFERENTIATION AND DEVELOPMENT : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF DEVELOPMENTAL BIOLOGISTS 1988; 25:99-108. [PMID: 3208194 DOI: 10.1016/0922-3371(88)90003-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The distribution of actin, tubulin and histone mRNAs is examined in full grown oocytes, meiotically mature eggs, and unicellular zygotes. For this analysis, oocytes, eggs and embryos were spatially divided into peripheral and central regions of both the animal and vegetal hemispheres, and the relative amounts and concentrations of these RNAs in each region were then determined. The concentration of actin and tubulin mRNAs is greatest in the periphery, whereas histone mRNA exhibits a uniform concentration throughout the oocyte. In the meiotically mature egg, actin mRNA is still concentrated in the periphery and histone mRNA still exhibits a relatively uniform concentration, but the tubulin mRNAs are more concentrated in the central regions. Following fertilization, however, the greatest concentration of mRNAs for actin, histone and tubulin is in the periphery of the zygote. The results demonstrate the existence of a system capable of altering the distributions of these mRNAs as well as a system which distinguishes between different types of mRNA.
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Affiliation(s)
- B A Perry
- Department of Zoology, Arizona State University, Tempe 85287-1501
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35
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Role of calcium in the localization of maternal poly(A)+RNA and tubulin mRNA in Xenopus oocytes. ACTA ACUST UNITED AC 1988; 197:175-183. [DOI: 10.1007/bf00427921] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/1987] [Accepted: 02/03/1988] [Indexed: 11/25/2022]
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36
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Capco DG, Mecca MD. Analysis of proteins in the peripheral and central regions of amphibian oocytes and eggs. CELL DIFFERENTIATION 1988; 23:155-64. [PMID: 3378266 DOI: 10.1016/0045-6039(88)90068-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Proteins in oocytes, meiotically mature eggs and zygotes of Xenopus laevis were examined to determine whether proteins in the peripheral region differ from those in the central region of these cells. We show that different regions contain different amounts of newly synthesized proteins and that during meiotic maturation and fertilization the periphery of the animal hemisphere becomes the site where most newly synthesized proteins are found. Examination of two-dimensional gels indicates that most of these proteins are found in all parts of the egg, but certain proteins demonstrate patterns of distribution which are indicative of (1) polarity, (2) developmental stage, and (3) the position within the hemisphere (central or peripheral). These results suggest that the periphery of oocytes, eggs, and zygotes is a site of greater metabolic activity compared with the central region.
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Affiliation(s)
- D G Capco
- Department of Zoology, Arizona State University, Tempe 85287
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37
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Longo FJ. Reorganization of the egg surface at fertilization. INTERNATIONAL REVIEW OF CYTOLOGY 1988; 113:233-69. [PMID: 3068182 DOI: 10.1016/s0074-7696(08)60850-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- F J Longo
- Department of Anatomy, University of Iowa, Iowa City 52242
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38
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Capco DG, Munoz DM, Gassmann CJ. A method for analysis of the detergent-resistant cytoskeleton of cells within organs. Tissue Cell 1987; 19:607-16. [PMID: 3424335 DOI: 10.1016/0040-8166(87)90068-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We describe a method for the preparation of the detergent-resistant cytoskeleton and nuclear matrix of cells within organs and tissues. Such cells were previously inaccessible to study because the three-dimensional organization of cells in organs prevented uniform distribution of the detergent throughout the multiple cell layers. We use the method presented here to compare the proteins present in the cytoskeleton, nuclear matrix and soluble fractions of cells from different histotypes. SDS-gel analysis demonstrates that soluble and nuclear matrix proteins differ greatly between histotypes while cytoskeletal proteins are relatively similar. Immunocytochemical analysis of tissue prepared using this procedure also demonstrates that the intracellular structure of cells within organs differs from that of in vitro cultured cells.
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Affiliation(s)
- D G Capco
- Department of Zoology, Arizona State University, Tempe 85287
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