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Edgar A, Mitchell DG, Martindale MQ. Whole-Body Regeneration in the Lobate Ctenophore Mnemiopsis leidyi. Genes (Basel) 2021; 12:genes12060867. [PMID: 34198839 PMCID: PMC8228598 DOI: 10.3390/genes12060867] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 01/28/2023] Open
Abstract
Ctenophores (a.k.a. comb jellies) are one of the earliest branching extant metazoan phyla. Adult regenerative ability varies greatly within the group, with platyctenes undergoing both sexual and asexual reproduction by fission while others in the genus Beroe having completely lost the ability to replace missing body parts. We focus on the unique regenerative aspects of the lobate ctenophore, Mnemiopsis leidyi, which has become a popular model for its rapid wound healing and tissue replacement, optical clarity, and sequenced genome. M. leidyi’s highly mosaic, stereotyped development has been leveraged to reveal the polar coordinate system that directs whole-body regeneration as well as lineage restriction of replacement cells in various regenerating organs. Several cell signaling pathways known to function in regeneration in other animals are absent from the ctenophore’s genome. Further research will either reveal ancient principles of the regenerative process common to all animals or reveal novel solutions to the stability of cell fates and whole-body regeneration.
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Abstract
Sex determination and sexual development are highly diverse and controlled by mechanisms that are extremely labile. While dioecy (separate male and female functions) is the norm for most animals, hermaphroditism (both male and female functions within a single body) is phylogenetically widespread. Much of our current understanding of sexual development comes from a small number of model systems, limiting our ability to make broader conclusions about the evolution of sexual diversity. We present the calyptraeid gastropods as a model for the study of the evolution of sex determination in a sequentially hermaphroditic system. Calyptraeid gastropods, a group of sedentary, filter-feeding marine snails, are sequential hermaphrodites that change sex from male to female during their life span (protandry). This transition includes resorption of the penis and the elaboration of female genitalia, in addition to shifting from production of spermatocytes to oocytes. This transition is typically under environmental control and frequently mediated by social interactions. Males in contact with females delay sex change to transition at larger sizes, while isolated males transition more rapidly and at smaller sizes. This phenomenon has been known for over a century; however, the mechanisms that control the switch from male to female are poorly understood. We review here our current understanding of sexual development and sex determination in the calyptraeid gastropods and other molluscs, highlighting our current understanding of factors implicated in the timing of sex change and the potential mechanisms. We also consider the embryonic origins and earliest expression of the germ line and the effects of environmental contaminants on sexual development.
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Suter B. RNA localization and transport. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:938-951. [PMID: 30496039 DOI: 10.1016/j.bbagrm.2018.08.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/23/2018] [Accepted: 08/23/2018] [Indexed: 12/30/2022]
Abstract
RNA localization serves numerous purposes from controlling development and differentiation to supporting the physiological activities of cells and organisms. After a brief introduction into the history of the study of mRNA localization I will focus on animal systems, describing in which cellular compartments and in which cell types mRNA localization was observed and studied. In recent years numerous novel localization patterns have been described, and countless mRNAs have been documented to accumulate in specific subcellular compartments. These fascinating revelations prompted speculations about the purpose of localizing all these mRNAs. In recent years experimental evidence for an unexpected variety of different functions has started to emerge. Aside from focusing on the functional aspects, I will discuss various ways of localizing mRNAs with a focus on the mechanism of active and directed transport on cytoskeletal tracks. Structural studies combined with imaging of transport and biochemical studies have contributed to the enormous recent progress, particularly in understanding how dynein/dynactin/BicD (DDB) dependent transport on microtubules works. This transport process actively localizes diverse cargo in similar ways to the minus end of microtubules and, at least in flies, also individual mRNA molecules. A sophisticated mechanism ensures that cargo loading licenses processive transport.
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Affiliation(s)
- Beat Suter
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland.
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4
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Yu L, Xu D, Ye H, Yue H, Ooka S, Kondo H, Yazawa R, Takeuchi Y. Gonadal Transcriptome Analysis of Pacific Abalone Haliotis discus discus: Identification of Genes Involved in Germ Cell Development. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2018; 20:467-480. [PMID: 29616430 DOI: 10.1007/s10126-018-9809-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 03/08/2018] [Indexed: 06/08/2023]
Abstract
Little is known about the molecular mechanisms governing gonadal developmental processes in abalones. Here, we conducted transcriptome analysis of Pacific abalone Haliotis discus discus for gene discovery in the brain, ovary, testis, and unfertilized eggs. Among the annotated unigenes, 48.6% of unigenes were identified by Venn diagram analysis as having universal or tissue-specific expression. Twenty-three genes with gonad-biased gene ontology (GO) terms were first obtained. Secondly, 36 genes were found by screening known gene names related to germ cell development. Finally, 17 genes were obtained by querying the annotated unigene database for zygotically expressed gonadal genes (ovary and testis) and maternally expressed gonadal genes (ovary, testis, and unfertilized eggs) using keywords related to reproduction. To further verify tissue distribution pattern and subcellular localization of these genes, RT-PCR and in situ hybridization were performed using a unigene encoding a germ cell marker, vasa, as control. The results showed that vasa was expressed mainly in the early developmental stages of germ cells in both sexes. One of the candidate genes, vitelline envelope zona pellucida domain protein 12 (ZP12), was expressed in the primordial germ cells of immature gonad and early developmental stages of germ cells of the adult female. The results obtained from the present study suggest that vasa and ZP12 are involved in germ cell development of Pacific abalone and that ZP12 is an especially useful germ cell-specific marker in immature adults. The current gonadal transcriptome profile is an extensive resource for future reproductive molecular biology studies of this species.
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Affiliation(s)
- Lingyun Yu
- Research Center for Advanced Science and Technology, Tokyo University of Marine Science and Technology, 670 Banda, Tateyama, Chiba, 294-0308, Japan
| | - Dongdong Xu
- Research Center for Advanced Science and Technology, Tokyo University of Marine Science and Technology, 670 Banda, Tateyama, Chiba, 294-0308, Japan
- Marine Fishery Institute of Zhejiang Province, Key Lab of Mariculture and Enhancement of Zhejiang Province, Zhoushan, Zhejiang Province, 316100, China
| | - Huan Ye
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, 430223, China
| | - Huamei Yue
- Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, 430223, China
| | - Shioh Ooka
- Japan Ocean Resources Development and Engineering Co., Ltd., 7-1 Jizohamacho, Kishiwada, Osaka, 596-0015, Japan
| | - Hidehiro Kondo
- Department of Marine Bioscience, Tokyo University of Marine Science and Technology, Minato, Konan 4-5-7, Tokyo, 108-8477, Japan
| | - Ryosuke Yazawa
- Department of Marine Bioscience, Tokyo University of Marine Science and Technology, Minato, Konan 4-5-7, Tokyo, 108-8477, Japan
| | - Yutaka Takeuchi
- Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima, 890-0056, Japan.
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Xu R, Li Q, Yu H, Kong L. Oocyte maturation and origin of the germline as revealed by the expression of Nanos-like in the Pacific oyster Crassostrea gigas. Gene 2018; 663:41-50. [PMID: 29660519 DOI: 10.1016/j.gene.2018.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/07/2018] [Accepted: 04/09/2018] [Indexed: 01/19/2023]
Abstract
Nanos gene plays an important role in germline development in animals. However, the molecular mechanisms involved in germline development in Mollusca, the second largest animal phylum, are still poorly understood. Here we identified the Nanos orthologue from the Pacific oyster Crassostrea gigas (Cg-Nanos-like), and investigated the expression patterns of Nanos during gametogenesis and embryogenesis in C. gigas. Tissue expression analysis showed that Cg-Nanos-like was specifically expressed in female gonads. During the reproductive cycle, the expression of Cg-Nanos-like mRNA increased matching the seasonal development of the ovarian tissues in diploids, while the expression levels were significantly lower in the ovaries of sterile triploids compared to diploids. High expression of Cg-Nanos-like transcripts were detected in early embryonic stages, while the expression significantly dropped at gastrulation and was barely detectable in veliger stages. In situ hybridization showed that Cg-Nanos-like was expressed at different stages of developing oocytes, whereas positive signals were detected only in spermatogonia during the spermatogenic cycle. These findings indicated that Cg-Nanos-like was involved in the development of germ cells, and maintenance of oocyte maturation. In early embryogenesis, the transcripts were broadly expressed; following gastrulation, the expression was restricted to two cell clumps, which might be the putative primordial germ cells (PGCs) or their precursors. Based on the results, the formation of the PGCs in C. gigas was consistent with the model of transition from epigenesis to preformation.
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Affiliation(s)
- Rui Xu
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
| | - Qi Li
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, China.
| | - Hong Yu
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China.
| | - Lingfeng Kong
- Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, China
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Özpolat BD, Handberg-Thorsager M, Vervoort M, Balavoine G. Cell lineage and cell cycling analyses of the 4d micromere using live imaging in the marine annelid Platynereis dumerilii. eLife 2017; 6:30463. [PMID: 29231816 PMCID: PMC5764573 DOI: 10.7554/elife.30463] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 12/11/2017] [Indexed: 11/13/2022] Open
Abstract
Cell lineage, cell cycle, and cell fate are tightly associated in developmental processes, but in vivo studies at single-cell resolution showing the intricacies of these associations are rare due to technical limitations. In this study on the marine annelid Platynereis dumerilii, we investigated the lineage of the 4d micromere, using high-resolution long-term live imaging complemented with a live-cell cycle reporter. 4d is the origin of mesodermal lineages and the germline in many spiralians. We traced lineages at single-cell resolution within 4d and demonstrate that embryonic segmental mesoderm forms via teloblastic divisions, as in clitellate annelids. We also identified the precise cellular origins of the larval mesodermal posterior growth zone. We found that differentially-fated progeny of 4d (germline, segmental mesoderm, growth zone) display significantly different cell cycling. This work has evolutionary implications, sets up the foundation for functional studies in annelid stem cells, and presents newly established techniques for live imaging marine embryos.
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Praher D, Zimmermann B, Genikhovich G, Columbus-Shenkar Y, Modepalli V, Aharoni R, Moran Y, Technau U. Characterization of the piRNA pathway during development of the sea anemone Nematostella vectensis. RNA Biol 2017; 14:1727-1741. [PMID: 28783426 PMCID: PMC5731801 DOI: 10.1080/15476286.2017.1349048] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
PIWI-interacting RNAs (piRNAs) and associated proteins comprise a conserved pathway for silencing transposons in metazoan germlines. piRNA pathway components are also expressed in multipotent somatic stem cells in various organisms. piRNA functions have been extensively explored in bilaterian model systems, however, comprehensive studies in non-bilaterian phyla remain limited. Here we investigate the piRNA pathway during the development of Nematostella vectensis, a well-established model system belonging to Cnidaria, the sister group to Bilateria. To date, no population of somatic stem cells has been identified in this organism, despite its long life-span and regenerative capacities that require a constant cell-renewal. We show that Nematostella piRNA pathway components are broadly expressed in early developmental stages, while piRNAs themselves show differential expression, suggesting specific developmental roles of distinct piRNA families. In adults, piRNA associated proteins are enriched in the germline but also expressed in somatic cells, indicating putative stem cell properties. Furthermore, we provide experimental evidence that Nematostella piRNAs cleave transposable elements as well as protein-coding genes. Our results demonstrate that somatic expression of piRNA associated proteins as well as the roles of piRNAs in transposon repression and gene regulation are likely ancestral features that evolved before the split between Cnidaria and Bilateria.
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Affiliation(s)
- Daniela Praher
- Department of Molecular Evolution and Development; Centre of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna; Althanstrasse 14, Wien, Austria
| | - Bob Zimmermann
- Department of Molecular Evolution and Development; Centre of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna; Althanstrasse 14, Wien, Austria
| | - Grigory Genikhovich
- Department of Molecular Evolution and Development; Centre of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna; Althanstrasse 14, Wien, Austria
| | - Yaara Columbus-Shenkar
- Department of Ecology, Evolution and Behavior; Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem; Givat Ram, Jerusalem, Israel
| | - Vengamanaidu Modepalli
- Department of Ecology, Evolution and Behavior; Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem; Givat Ram, Jerusalem, Israel
| | - Reuven Aharoni
- Department of Ecology, Evolution and Behavior; Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem; Givat Ram, Jerusalem, Israel
| | - Yehu Moran
- Department of Ecology, Evolution and Behavior; Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem; Givat Ram, Jerusalem, Israel
| | - Ulrich Technau
- Department of Molecular Evolution and Development; Centre of Organismal Systems Biology, Faculty of Life Sciences, University of Vienna; Althanstrasse 14, Wien, Austria
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Milani L, Pecci A, Ghiselli F, Passamonti M, Bettini S, Franceschini V, Maurizii MG. VASA expression suggests shared germ line dynamics in bivalve molluscs. Histochem Cell Biol 2017; 148:157-171. [PMID: 28386635 PMCID: PMC5508042 DOI: 10.1007/s00418-017-1560-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2017] [Indexed: 11/25/2022]
Abstract
Germ line segregation can occur during embryogenesis or after embryogenesis completion, with multipotent cells able to give rise to both germ and somatic cells in the developing juvenile or even in adulthood. These undifferentiated cells, in some animals, are self-renewing stem cells. In all these cell lineages, the same set of genes, among which vasa, appears to be expressed. We traced VASA expression during the peculiar gonad rebuilding of bivalves to verify its presence from undifferentiated germ cells to mature gametes in an animal taxon in which the mechanism of germ line establishment is still under investigation. We utilized antibodies produced against VASPH, VASA homolog of Ruditapes philippinarum (Subclass Heterodonta), to compare the known expression pattern of R. philippinarum to two species of the Subclass Pteriomorphia, Anadara kagoshimensis and Crassostrea gigas, and another species of the Subclass Heterodonta, Mya arenaria. The immunohistological data obtained support a conserved mechanism of proliferation of "primordial stem cells" among the simple columnar epithelium of the gut, as well as in the connective tissue, contributing to the seasonal gonad reconstitution. Given the taxonomic separation of the analyzed species, we suggest that the process could be shared in bivalve molluscs. The presence of germ cell precursors in the gut epithelium appears to be a feature in common with model organisms, such as mouse, fruit fly, and human. Thus, the comparative study of germ line establishment can add details on bivalve development, but can also help to clarify the role that VASA plays during germ cell specification.
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Affiliation(s)
- Liliana Milani
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy.
| | - Andrea Pecci
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Fabrizio Ghiselli
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Marco Passamonti
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Simone Bettini
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Valeria Franceschini
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Maria Gabriella Maurizii
- Department of Scienze Biologiche, Geologiche ed Ambientali, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
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9
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Oulhen N, Heyland A, Carrier TJ, Zazueta-Novoa V, Fresques T, Laird J, Onorato TM, Janies D, Wessel G. Regeneration in bipinnaria larvae of the bat star Patiria miniata induces rapid and broad new gene expression. Mech Dev 2016; 142:10-21. [PMID: 27555501 PMCID: PMC5154901 DOI: 10.1016/j.mod.2016.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 11/23/2022]
Abstract
BACKGROUND Some metazoa have the capacity to regenerate lost body parts. This phenomenon in adults has been classically described in echinoderms, especially in sea stars (Asteroidea). Sea star bipinnaria larvae can also rapidly and effectively regenerate a complete larva after surgical bisection. Understanding the capacity to reverse cell fates in the larva is important from both a developmental and biomedical perspective; yet, the mechanisms underlying regeneration in echinoderms are poorly understood. RESULTS Here, we describe the process of bipinnaria regeneration after bisection in the bat star Patiria miniata. We tested transcriptional, translational, and cell proliferation activity after bisection in anterior and posterior bipinnaria halves as well as expression of SRAP, reported as a sea star regeneration associated protease (Vickery et al., 2001b). Moreover, we found several genes whose transcripts increased in abundance following bisection, including: Vasa, dysferlin, vitellogenin 1 and vitellogenin 2. CONCLUSION These results show a transformation following bisection, especially in the anterior halves, of cell fate reassignment in all three germ layers, with clear and predictable changes. These results define molecular events that accompany the cell fate changes coincident to the regenerative response in echinoderm larvae.
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Affiliation(s)
- Nathalie Oulhen
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA
| | - Andreas Heyland
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA; University of Guelph, Integrative Biology, Canada.
| | - Tyler J Carrier
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA; University of North Carolina at Charlotte, Department of Biological Sciences, USA
| | | | - Tara Fresques
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA
| | - Jessica Laird
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA
| | | | - Daniel Janies
- University of North Carolina at Charlotte, Department of Bioinformatics and Genomics, USA
| | - Gary Wessel
- Brown University, Molecular Biology, Cell Biology, and Biochemistry, USA.
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10
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Kozin VV, Kostyuchenko RP. Evolutionary conservation and variability of the mesoderm development in spiralia: A peculiar pattern of nereid polychaetes. BIOL BULL+ 2016. [DOI: 10.1134/s1062359016030079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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11
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Abstract
Primordial germ cells are usually made early in the development of an organism. These are the mother of all stem cells that are necessary for propagation of the species, yet use highly diverse mechanisms between organisms. How they are specified, and when and where they form, are central to developmental biology. Using diverse organisms to study this development is illuminating for understanding the mechanics these cells use in this essential function and for identifying the breadth of evolutionary changes that have occurred between species. This essay emphasizes how echinoderms may contribute to the patchwork quilt of our understanding of germ line formation during embryogenesis.
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Affiliation(s)
- Gary M Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA.
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12
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Abstract
With few exceptions, all animals acquire the ability to produce eggs or sperm at some point in their life cycle. Despite this near-universal requirement for sexual reproduction, there exists an incredible diversity in germ line development. For example, animals exhibit a vast range of differences in the timing at which the germ line, which retains reproductive potential, separates from the soma, or terminally differentiated, nonreproductive cells. This separation may occur during embryonic development, after gastrulation, or even in adults, depending on the organism. The molecular mechanisms of germ line segregation are also highly diverse, and intimately intertwined with the overall transition from a fertilized egg to an embryo. The earliest embryonic stages of many species are largely controlled by maternally supplied factors. Later in development, patterning control shifts to the embryonic genome and, concomitantly with this transition, the maternally supplied factors are broadly degraded. This chapter attempts to integrate these processes--germ line segregation, and how the divergence of germ line and soma may utilize the egg to embryo transitions differently. In some embryos, this difference is subtle or maybe lacking altogether, whereas in other embryos, this difference in utilization may be a key step in the divergence of the two lineages. Here, we will focus our discussion on the echinoderms, and in particular the sea urchins, in which recent studies have provided mechanistic understanding in germ line determination. We propose that the germ line in sea urchins requires an acquisition of maternal factors from the egg and, when compared to other members of the taxon, this appears to be a derived mechanism. The acquisition is early--at the 32-cell stage--and involves active protection of maternal mRNAs, which are instead degraded in somatic cells with the maternal-to-embryonic transition. We collectively refer to this model as the Time Capsule method for germ line determination.
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Affiliation(s)
- S Zachary Swartz
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA
| | - Gary M Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA.
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13
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Kumano G. Evolution of germline segregation processes in animal development. Dev Growth Differ 2015; 57:324-32. [DOI: 10.1111/dgd.12211] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/05/2015] [Accepted: 03/05/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Gaku Kumano
- Asamushi Research Center for Marine Biology; Graduate School of Life Science; Tohoku University; 9 Sakamoto Asamushi Aomori 039-3501 Japan
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14
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Schwager EE, Meng Y, Extavour CG. vasa and piwi are required for mitotic integrity in early embryogenesis in the spider Parasteatoda tepidariorum. Dev Biol 2014; 402:276-90. [PMID: 25257304 DOI: 10.1016/j.ydbio.2014.08.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 08/13/2014] [Accepted: 08/29/2014] [Indexed: 11/30/2022]
Abstract
Studies in vertebrate and invertebrate model organisms on the molecular basis of primordial germ cell (PGC) specification have revealed that metazoans can specify their germ line either early in development by maternally transmitted cytoplasmic factors (inheritance), or later in development by signaling factors from neighboring tissues (induction). Regardless of the mode of PGC specification, once animal germ cells are specified, they invariably express a number of highly conserved genes. These include vasa and piwi, which can play essential roles in any or all of PGC specification, development, or gametogenesis. Although the arthropods are the most speciose animal phylum, to date there have been no functional studies of conserved germ line genes in species of the most basally branching arthropod clade, the chelicerates (which includes spiders, scorpions, and horseshoe crabs). Here we present the first such study by using molecular and functional tools to examine germ line development and the roles of vasa and piwi orthologues in the common house spider Parasteatoda (formerly Achaearanea) tepidariorum. We use transcript and protein expression patterns of Pt-vasa and Pt-piwi to show that primordial germ cells (PGCs) in the spider arise during late embryogenesis. Neither Pt-vasa nor Pt-piwi gene products are localized asymmetrically to any embryonic region before PGCs emerge as paired segmental clusters in opisthosomal segments 2-6 at late germ band stages. RNA interference studies reveal that both genes are required maternally for egg laying, mitotic progression in early embryos, and embryonic survival. Our results add to the growing body of evidence that vasa and piwi can play important roles in somatic development, and provide evidence for a previously hypothesized conserved role for vasa in cell cycle progression.
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Affiliation(s)
- Evelyn E Schwager
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA 02138, USA
| | - Yue Meng
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA 02138, USA
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave, Cambridge, MA 02138, USA.
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15
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Pfeifer K, Schaub C, Domsch K, Dorresteijn A, Wolfstetter G. Maternal inheritance of twist and analysis of MAPK activation in embryos of the polychaete annelid Platynereis dumerilii. PLoS One 2014; 9:e96702. [PMID: 24792484 PMCID: PMC4008618 DOI: 10.1371/journal.pone.0096702] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 04/10/2014] [Indexed: 11/18/2022] Open
Abstract
In this study, we aimed to identify molecular mechanisms involved in the specification of the 4d (mesentoblast) lineage in Platynereis dumerilii. We employ RT-PCR and in situ hybridization against the Platynereis dumerilii twist homolog (Pdu-twist) to reveal mesodermal specification within this lineage. We show that Pdu-twist mRNA is already maternally distributed. After fertilization, ooplasmatic segregation leads to relocation of Pdu-twist transcripts into the somatoblast (2d) lineage and 4d, indicating that the maternal component of Pdu-twist might be an important prerequisite for further mesoderm specification but does not represent a defining characteristic of the mesentoblast. However, after the primordial germ cells have separated from the 4d lineage, zygotic transcription of Pdu-twist is exclusively observed in the myogenic progenitors, suggesting that mesodermal specification occurs after the 4d stage. Previous studies on spiral cleaving embryos revealed a spatio-temporal correlation between the 4d lineage and the activity of an embryonic organizer that is capable to induce the developmental fates of certain micromeres. This has raised the question if specification of the 4d lineage could be connected to the organizer activity. Therefore, we aimed to reveal the existence of such a proposed conserved organizer in Platynereis employing antibody staining against dpERK. In contrast to former observations in other spiralian embryos, activation of MAPK signaling during 2d and 4d formation cannot be detected which questions the existence of a conserved connection between organizer function and specification of the 4d lineage. However, our experiments unveil robust MAPK activation in the prospective nephroblasts as well as in the macromeres and some micromeres at the blastopore in gastrulating embryos. Inhibition of MAPK activation leads to larvae with a shortened body axis, defects in trunk muscle spreading and improper nervous system condensation, indicating a critical function for MAPK signaling for the reorganization of embryonic tissues during the gastrulation process.
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Affiliation(s)
- Kathrin Pfeifer
- Institut für Allgemeine und Spezielle Zoologie; Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Gieβen, Gieβen, Germany
| | - Christoph Schaub
- Institut für Allgemeine und Spezielle Zoologie; Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Gieβen, Gieβen, Germany
| | - Katrin Domsch
- Institut für Allgemeine und Spezielle Zoologie; Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Gieβen, Gieβen, Germany
| | - Adriaan Dorresteijn
- Institut für Allgemeine und Spezielle Zoologie; Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Gieβen, Gieβen, Germany
| | - Georg Wolfstetter
- Institut für Allgemeine und Spezielle Zoologie; Allgemeine Zoologie und Entwicklungsbiologie, Justus-Liebig-Universität Gieβen, Gieβen, Germany
- * E-mail:
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16
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Matsumoto T, Masaoka T, Fujiwara A, Nakamura Y, Satoh N, Awaji M. Reproduction-related genes in the pearl oyster genome. Zoolog Sci 2013; 30:826-50. [PMID: 24125647 DOI: 10.2108/zsj.30.826] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Molluscan reproduction has been a target of biological research because of the various reproductive strategies that have evolved in this phylum. It has also been studied for the development of fisheries technologies, particularly aquaculture. Although fundamental processes of reproduction in other phyla, such as vertebrates and arthropods, have been well studied, information on the molecular mechanisms of molluscan reproduction remains limited. The recently released draft genome of the pearl oyster Pinctada fucata provides a novel and powerful platform for obtaining structural information on the genes and proteins involved in bivalve reproduction. In the present study, we analyzed the pearl oyster draft genome to screen reproduction-related genes. Analysis was mainly conducted for genes reported from other molluscs for encoding orthologs of reproduction-related proteins in other phyla. The gene search in the P. fucata gene models (version 1.1) and genome assembly (version 1.0) were performed using Genome Browser and BLAST software. The obtained gene models were then BLASTP searched against a public database to confirm the best-hit sequences. As a result, more than 40 gene models were identified with high accuracy to encode reproduction-related genes reported for P. fucata and other molluscs. These include vasa, nanos, doublesex- and mab-3-related transcription factor, 5-hydroxytryptamine (5-HT) receptors, vitellogenin, estrogen receptor, and others. The set of reproduction-related genes of P. fucata identified in the present study constitute a new tool for research on bivalve reproduction at the molecular level.
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Affiliation(s)
- Toshie Matsumoto
- 1 Aquaculture Technology Division, National Research Institute of Aquaculture, Fisheries Research Agency, Minami-lse, Watarai, Mie 516-0193, Japan
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Cho SJ, Vallès Y, Weisblat DA. Differential expression of conserved germ line markers and delayed segregation of male and female primordial germ cells in a hermaphrodite, the leech helobdella. Mol Biol Evol 2013; 31:341-54. [PMID: 24217283 PMCID: PMC3907050 DOI: 10.1093/molbev/mst201] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
In sexually reproducing animals, primordial germ cells (PGCs) are often set aside early in embryogenesis, a strategy that minimizes the risk of genomic damage associated with replication and mitosis during the cell cycle. Here, we have used germ line markers (piwi, vasa, and nanos) and microinjected cell lineage tracers to show that PGC specification in the leech genus Helobdella follows a different scenario: in this hermaphrodite, the male and female PGCs segregate from somatic lineages only after more than 20 rounds of zygotic mitosis; the male and female PGCs share the same (mesodermal) cell lineage for 19 rounds of zygotic mitosis. Moreover, while all three markers are expressed in both male and female reproductive tissues of the adult, they are expressed differentially between the male and female PGCs of the developing embryo: piwi and vasa are expressed preferentially in female PGCs at a time when nanos is expressed preferentially in male PGCs. A priori, the delayed segregation of male and female PGCs from somatic tissues and from one another increases the probability of mutations affecting both male and female PGCs of a given individual. We speculate that this suite of features, combined with a capacity for self-fertilization, may contribute to the dramatically rearranged genome of Helobdella robusta relative to other animals.
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Affiliation(s)
- Sung-Jin Cho
- Department of Molecular and Cell Biology, LSA, University of California, Berkeley
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18
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Ewen-Campen B, Donoughe S, Clarke DN, Extavour CG. Germ cell specification requires zygotic mechanisms rather than germ plasm in a basally branching insect. Curr Biol 2013; 23:835-42. [PMID: 23623552 DOI: 10.1016/j.cub.2013.03.063] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 03/03/2013] [Accepted: 03/22/2013] [Indexed: 12/25/2022]
Abstract
BACKGROUND Primordial germ cell (PGC) specification is a universal process across animals, but the molecular mechanisms specifying PGCs are remarkably diverse. In Drosophila, PGCs are specified by maternally provided, asymmetrically localized cytoplasmic factors (germ plasm). In contrast, historical literature on most other arthropods reports that PGCs arise from mesoderm during midembryogenesis, suggesting that an arthropod last common ancestor may have specified PGCs via zygotic mechanisms. However, there has been no direct experimental evidence to date for germ plasm-independent arthropod PGC specification. RESULTS Here we show that in a basally branching insect, the cricket Gryllus bimaculatus, conserved germ plasm molecules are ubiquitously, rather than asymmetrically, localized during oogenesis and early embryogenesis. Molecular and cytological analyses suggest that Gryllus PGCs arise from abdominal mesoderm during segmentation, and twist RNAi embryos that lack mesoderm fail to form PGCs. Using RNA interference we show that vasa and piwi are not required maternally or zygotically for PGC formation but rather are required for primary spermatogonial divisions in adult males. CONCLUSIONS These observations suggest that Gryllus lacks a maternally inherited germ plasm, in contrast with many holometabolous insects, including Drosophila. The mesodermal origin of Gryllus PGCs and absence of instructive roles for vasa and piwi in PGC formation are reminiscent of mouse PGC specification and suggest that zygotic cell signaling may direct PGC specification in Gryllus and other Hemimetabola.
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Affiliation(s)
- Ben Ewen-Campen
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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19
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Fischer AH, Arendt D. Mesoteloblast-Like Mesodermal Stem Cells in the Polychaete AnnelidPlatynereis dumerilii(Nereididae). JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2013; 320:94-104. [DOI: 10.1002/jez.b.22486] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 10/12/2012] [Accepted: 12/17/2012] [Indexed: 01/22/2023]
Affiliation(s)
- Antje H.L. Fischer
- Developmental Biology Unit; European Molecular Biology Laboratory; Heidelberg; Germany
| | - Detlev Arendt
- Developmental Biology Unit; European Molecular Biology Laboratory; Heidelberg; Germany
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20
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Solana J. Closing the circle of germline and stem cells: the Primordial Stem Cell hypothesis. EvoDevo 2013; 4:2. [PMID: 23294912 PMCID: PMC3599645 DOI: 10.1186/2041-9139-4-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 12/04/2012] [Indexed: 01/14/2023] Open
Abstract
Background Germline determination is believed to occur by either preformation or epigenesis. Animals that undergo germ cell specification by preformation have a continuous germline. However, animals with germline determination by epigenesis have a discontinuous germline, with somatic cells intercalated. This vision is contrary to August Weismann’s Germ Plasm Theory and has led to several controversies. Recent data from metazoans as diverse as planarians, annelids and sea urchins reveal the presence of pluripotent stem cell populations that express germ plasm components, despite being considered to be somatic. These data also show that germ plasm is continuous in some of these animals, despite their discontinuous germline. Presentation of the hypothesis Here, based on recent molecular data on germ plasm components, I revise the germline concept. I introduce the concept of primordial stem cells, which are evolutionarily conserved stem cells that carry germ plasm components from the zygote to the germ cells. These cells, delineated by the classic concept of the Weismann barrier, can contribute to different extents to somatic tissues or be present in a rudimentary state. The primordial stem cells are a part of the germline that can drive asexual reproduction. Testing the hypothesis Molecular information on the expression of germ plasm components is needed during early development of non-classic model organisms, with special attention to those capable of undergoing asexual reproduction and regeneration. The cell lineage of germ plasm component-containing cells will also shed light on their position with respect to the Weismann barrier. This information will help in understanding the germline and its associated stem cells across metazoan phylogeny. Implications of the hypothesis This revision of the germline concept explains the extensive similarities observed among stem cells and germline cells in a wide variety of animals, and predicts the expression of germ plasm components in many others. The life history of these animals can be simply explained by changes in the extent of self-renewal, proliferation and developmental potential of the primordial stem cells. The inclusion of the primordial stem cells as a part of the germline, therefore, solves many controversies and provides a continuous germline, just as originally envisaged by August Weismann.
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Affiliation(s)
- Jordi Solana
- Laboratory of Systems Biology of Gene Regulatory Elements, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
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21
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Lyons DC, Perry KJ, Lesoway MP, Henry JQ. Cleavage pattern and fate map of the mesentoblast, 4d, in the gastropod Crepidula: a hallmark of spiralian development. EvoDevo 2012; 3:21. [PMID: 22992254 PMCID: PMC3724503 DOI: 10.1186/2041-9139-3-21] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/24/2012] [Indexed: 11/10/2022] Open
Abstract
Background Animals with a spiral cleavage program, such as mollusks and annelids, make up the majority of the superphylum Lophotrochozoa. The great diversity of larval and adult body plans in this group emerges from this highly conserved developmental program. The 4d micromere is one of the most conserved aspects of spiralian development. Unlike the preceding pattern of spiral divisions, cleavages within the 4d teloblastic sublineages are bilateral, representing a critical transition towards constructing the bilaterian body plan. These cells give rise to the visceral mesoderm in virtually all spiralians examined and in many species they also contribute to the endodermal intestine. Hence, the 4d lineage is an ideal one for studying the evolution and diversification of the bipotential endomesodermal germ layer in protostomes at the level of individual cells. Little is known of how division patterns are controlled or how mesodermal and endodermal sublineages diverge in spiralians. Detailed modern fate maps for 4d exist in only a few species of clitellate annelids, specifically in glossiphoniid leeches and the sludge worm Tubifex. We investigated the 4d lineage in the gastropod Crepidula fornicata, an established model system for spiralian biology, and in a closely related direct-developing species, C. convexa. Results High-resolution cell lineage tracing techniques were used to study the 4d lineage of C. fornicata and C. convexa. We present a new nomenclature to name the progeny of 4d, and report the fate map for the sublineages up through the birth of the first five pairs of teloblast daughter cells (when 28 cells are present in the 4d sublineage), and describe each clone’s behavior during gastrulation and later stages as these undergo differentiation. We identify the precise origin of the intestine, two cells of the larval kidney complex, the larval retractor muscles and the presumptive germ cells, among others. Other tissues that arise later in the 4d lineage include the adult heart, internal foot tissues, and additional muscle and mesenchymal cells derived from later-born progeny of the left and right teloblasts. To test whether other cells can compensate for the loss of these tissues (that is, undergo regulation), specific cells were ablated in C. fornicata. Conclusions Our results present the first fate map of the 4d micromere sublineages in a mollusk. The fate map reveals that endodermal and mesodermal fates segregate much later than previously thought. We observed little evidence of regulation between sublineages, consistent with a lineage-driven cell specification process. Our results provide a framework for comparisons with other spiralians and lay the groundwork for investigation of the molecular mechanisms of endomesoderm formation, germ line segregation and bilateral differentiation in Crepidula.
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Affiliation(s)
- Deirdre C Lyons
- Department of Cell and Developmental Biology, University of Illinois, 601 South Goodwin Avenue, Urbana, IL 61801, USA.
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22
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Rebscher N, Lidke AK, Ackermann CF. Hidden in the crowd: primordial germ cells and somatic stem cells in the mesodermal posterior growth zone of the polychaete Platynereis dumerillii are two distinct cell populations. EvoDevo 2012; 3:9. [PMID: 22512981 PMCID: PMC3348064 DOI: 10.1186/2041-9139-3-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 04/18/2012] [Indexed: 01/09/2023] Open
Abstract
Background In the polychaete Platynereis, the primordial germ cells (PGCs) emerge from the vasa, piwi, and PL10 expressing mesodermal posterior growth zone (MPGZ) at the end of larval development, suggesting a post-embryonic formation from stem cells. Methods In order to verify this hypothesis, embryos and larvae were pulse labeled with the proliferation marker 5-ethynyl-2'-deoxyuridine (EdU) at different stages of development. Subsequently, the PGCs were visualized in 7-day-old young worms using antibodies against the Vasa protein. Results Surprisingly, the primordial germ cells of Platynereis incorporate EdU only shortly before gastrulation (6-8 hours post fertilization (hpf)), which coincides with the emergence of four small blastomeres from the mesoblast lineage. We conclude that these so-called 'secondary mesoblast cells' constitute the definitive PGCs in Platynereis. In contrast, the cells of the MPGZ incorporate EdU only from the pre-trochophore stage onward (14 hpf). Conclusion While PGCs and the cells of the MPGZ in Platynereis are indistinguishable in morphology and both express the germline markers vasa, nanos, and piwi, a distinct cluster of PGCs is detectable anterior of the MPGZ following EdU pulse-labeling. Indeed the PGCs form independently from the stem cells of the MPGZ prior to gastrulation. Our data suggest an early PGC formation in the polychaete by preformation rather than by epigenesis.
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Affiliation(s)
- Nicole Rebscher
- Morphology and Evolution of Invertebrates, Philipps-Universität Marburg, Karl von Frisch Strasse 8, 35032 Marburg, Germany.
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23
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Maternally localized germ plasm mRNAs and germ cell/stem cell formation in the cnidarian Clytia. Dev Biol 2012; 364:236-48. [DOI: 10.1016/j.ydbio.2012.01.018] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 01/11/2012] [Accepted: 01/20/2012] [Indexed: 01/07/2023]
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24
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Milani L, Ghiselli F, Maurizii MG, Passamonti M. Doubly uniparental inheritance of mitochondria as a model system for studying germ line formation. PLoS One 2011; 6:e28194. [PMID: 22140544 PMCID: PMC3226660 DOI: 10.1371/journal.pone.0028194] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/02/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Doubly Uniparental Inheritance (DUI) of mitochondria occurs when both mothers and fathers are capable of transmitting mitochondria to their offspring, in contrast to the typical Strictly Maternal Inheritance (SMI). DUI was found in some bivalve molluscs, in which two mitochondrial genomes are inherited, one through eggs, the other through sperm. During male embryo development, spermatozoon mitochondria aggregate in proximity of the first cleavage furrow and end up in the primordial germ cells, while they are dispersed in female embryos. METHODOLOGY/PRINCIPAL FINDINGS We used MitoTracker, microtubule staining and transmission electron microscopy to examine the mechanisms of this unusual distribution of sperm mitochondria in the DUI species Ruditapes philippinarum. Our results suggest that in male embryos the midbody deriving from the mitotic spindle of the first division concurs in positioning the aggregate of sperm mitochondria. Furthermore, an immunocytochemical analysis showed that the germ line determinant Vasa segregates close to the first cleavage furrow. CONCLUSIONS/SIGNIFICANCE In DUI male embryos, spermatozoon mitochondria aggregate in a stable area on the animal-vegetal axis: in organisms with spiral segmentation this zone is not involved in cleavage, so the aggregation is maintained. Moreover, sperm mitochondria reach the same embryonic area in which also germ plasm is transferred. In 2-blastomere embryos, the segregation of sperm mitochondria in the same region with Vasa suggests their contribution in male germ line formation. In DUI male embryos, M-type mitochondria must be recognized by egg factors to be actively transferred in the germ line, where they become dominant replacing the Balbiani body mitochondria. The typical features of germ line assembly point to a common biological mechanism shared by DUI and SMI organisms. Although the molecular dynamics of the segregation of sperm mitochondria in DUI species are unknown, they could be a variation of the mechanism regulating the mitochondrial bottleneck in all metazoans.
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Affiliation(s)
- Liliana Milani
- Department of Biologia Evoluzionistica Sperimentale, University of Bologna, Bologna, Italy.
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25
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Abstract
The localization of mRNAs in developing animal cells is essential for establishing cellular polarity and setting up the body plan for subsequent development. Cellular and molecular mechanisms by which maternal mRNAs are localized during oogenesis have been extensively studied in Drosophila and Xenopus. In contrast, evidence for mechanisms used in the localization of mRNAs encoded by developmentally important genes has also been accumulating in several other organisms. This offers the opportunity to unravel the fundamental mechanisms of mRNA localization shared among many species, as well as unique mechanisms specifically acquired or retained by animals based on their developmental needs. In addition to maternal mRNAs, the localization of zygotically expressed mRNAs in the cells of cleaving embryos is also important for early development. In this review, mRNA localization dynamics in the oocytes/eggs of Drosophila and Xenopus are first summarized, and evidence for localized mRNAs in the oocytes/eggs and cleaving embryos of other organisms is then presented.
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Affiliation(s)
- Gaku Kumano
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
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26
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Wu HR, Chen YT, Su YH, Luo YJ, Holland LZ, Yu JK. Asymmetric localization of germline markers Vasa and Nanos during early development in the amphioxus Branchiostoma floridae. Dev Biol 2011; 353:147-59. [DOI: 10.1016/j.ydbio.2011.02.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 02/15/2011] [Accepted: 02/15/2011] [Indexed: 10/18/2022]
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Gustafson EA, Wessel GM. Vasa genes: emerging roles in the germ line and in multipotent cells. Bioessays 2011; 32:626-37. [PMID: 20586054 DOI: 10.1002/bies.201000001] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Sexually reproducing metazoans establish a cell lineage during development that is ultimately dedicated to gamete production. Work in a variety of animals suggests that a group of conserved molecular determinants act in this germ line maintenance and function. The most universal of these genes are Vasa and Vasa-like DEAD-box RNA helicase genes. However, recent evidence indicates that Vasa genes also function in other cell types, distinct from the germ line. Here we evaluate our current understanding of Vasa function and its regulation during development, addressing Vasa's emerging role in multipotent cells. We also explore the evolutionary diversification of the N-terminal domain of this gene and how this impacts the association of Vasa with nuage-like perinuclear structures.
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Affiliation(s)
- Eric A Gustafson
- Providence Institute of Molecular Oogenesis Department of Molecular Biology, Cell Biology and Biochemistry Brown University Providence, RI 02912, USA
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28
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Gline SE, Nakamoto A, Cho SJ, Chi C, Weisblat DA. Lineage analysis of micromere 4d, a super-phylotypic cell for Lophotrochozoa, in the leech Helobdella and the sludgeworm Tubifex. Dev Biol 2011; 353:120-33. [PMID: 21295566 DOI: 10.1016/j.ydbio.2011.01.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 01/14/2023]
Abstract
The super-phylum Lophotrochozoa contains the plurality of extant animal phyla and exhibits a corresponding diversity of adult body plans. Moreover, in contrast to Ecdysozoa and Deuterostomia, most lophotrochozoans exhibit a conserved pattern of stereotyped early divisions called spiral cleavage. In particular, bilateral mesoderm in most lophotrochozoan species arises from the progeny of micromere 4d, which is assumed to be homologous with a similar cell in the embryo of the ancestral lophotrochozoan, more than 650 million years ago. Thus, distinguishing the conserved and diversified features of cell fates in the 4d lineage among modern spiralians is required to understand how lophotrochozoan diversity has evolved by changes in developmental processes. Here we analyze cell fates for the early progeny of the bilateral daughters (M teloblasts) of micromere 4d in the leech Helobdella sp. Austin, a clitellate annelid. We show that the first six progeny of the M teloblasts (em1-em6) contribute five different sets of progeny to non-segmental mesoderm, mainly in the head and in the lining of the digestive tract. The latter feature, associated with cells em1 and em2 in Helobdella, is seen with the M teloblast lineage in a second clitellate species, the sludgeworm Tubifex tubifex and, on the basis of previously published work, in the initial progeny of the M teloblast homologs in molluscan species, suggesting that it may be an ancestral feature of lophotrochozoan development.
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Affiliation(s)
- Stephanie E Gline
- Dept. of Molecular and Cell Biology, 385 LSA, University of California, Berkeley, CA 94720-3200, USA
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29
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Abstract
The germline of multicellular animals is segregated from somatic tissues, which is an essential developmental process for the next generation. Although certain ecdysozoans and chordates segregate their germline during embryogenesis, animals from other taxa segregate their germline after embryogenesis from multipotent progenitor cells. An overlapping set of genes, including vasa, nanos and piwi, operate in both multipotent precursors and in the germline. As we propose here, this conservation implies the existence of an underlying germline multipotency program in these cell types that has a previously underappreciated and conserved function in maintaining multipotency.
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Affiliation(s)
- Celina E. Juliano
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
| | - S. Zachary Swartz
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
| | - Gary M. Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, RI 02912, USA
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30
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Kranz AM, Tollenaere A, Norris BJ, Degnan BM, Degnan SM. Identifying the germline in an equally cleaving mollusc: Vasa and Nanos expression during embryonic and larval development of the vetigastropod Haliotis asinina. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2010; 314:267-79. [PMID: 20095031 DOI: 10.1002/jez.b.21336] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Members of the Vasa and Nanos gene families are important for the specification and development of the germline in diverse animals. Here, we determine spatial and temporal expression of Vasa and Nanos to investigate germline development in the vetigastropod Haliotis asinina. This is the first time these genes have been examined in an equally cleaving lophotrochozoan species. We find that HasVasa and HasNanos have largely overlapping, but not identical, expression patterns during embryonic and larval development, with both being maternally expressed and localized to the micromere cell lineages during cleavage. As embryonic development continues, HasVasa and HasNanos become progressively more enriched in the dorsal quadrant of the embryo. By the trochophore stage, both HasVasa and HasNanos are expressed in the putative mesodermal bands of the larva. This differs from the unequally cleaving gastropod Illyanasa obsoleta, in which IoVasa and IoNanos expression is detectable only in the early embryo and not during gastrulation and larval development. Our results suggest that the H. asinina germline arises from the 4d cell lineage and that primordial germ cells (PGCs) are not specified exclusively by maternally inherited determinants (preformation). As such, we infer that inductive signals (epigenesis) play an important role in specifying PGCs in H. asinina. We hypothesize that HasVasa is expressed in a population of undifferentiated multipotent cells, from which the PGCs are segregated later during development.
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Affiliation(s)
- Alexandrea M Kranz
- The University of Queensland, School of Biological Sciences, Brisbane, Queensland, Australia
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31
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Obata M, Sano N, Kimata S, Nagasawa K, Yoshizaki G, Komaru A. The proliferation and migration of immature germ cells in the mussel, Mytilus galloprovincialis: observation of the expression pattern in the M. galloprovincialis vasa-like gene (Myvlg) by in situ hybridization. Dev Genes Evol 2010; 220:139-49. [PMID: 20725841 DOI: 10.1007/s00427-010-0335-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 07/24/2010] [Indexed: 10/19/2022]
Abstract
In bivalve, the distribution of primordial germ cells can be traced from early embryogenesis to the veliger larva by the expression of the vasa ortholog. However, the distribution of germ cells from metamorphosis to maturation in bivalves has not been examined extensively. In this study, we used in situ hybridization to observe expression of the Mytilus galloprovincialis vasa-like gene (Myvlg). The distribution of germ cells was clarified in immature mussels. We observed germ cells in adult mussels during the non-reproductive and reproductive seasons. Myvlg was specifically expressed in germ cells. Gametogenesis occurs in acini surrounded by connective tissue. Myvlg expression was detected in spermatogonia, spermatocytes, oogonia, and oocytes. In the non-reproductive season, gametes were not observed in the acini, but Myvlg was expressed in germinal stem cells along the acini. The expression intensity in the non-reproductive season, however, was much weaker than that in the reproductive season. Myvlg-positive cells proliferated during the non-reproductive season. In immature mussels, a pair of germ cell clumps was distributed laterally in the connective tissue between the nephric tubules and posterior byssal retractor muscle. Germ cells were also observed along pericardium. When immature mussels grew, a pair of germ cell clumps migrated anteriorly in the connective tissue along the outer epithelium at the dorsal region of the mantle base between the mantle and gill. The number of germ cells increased significantly as the mussels grew. This is the first report to observe the proliferation and migration of germ cells in immature mussels.
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Affiliation(s)
- Mayu Obata
- Faculty of Bioresources, Mie University, 1577 Kurimamachiya, Tsu, Mie, 514-8507, Japan.
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32
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Abstract
When do germ cells establish their separate, independent identity during animal development?
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Affiliation(s)
- Celina Juliano
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA. 02912
| | - Gary Wessel
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA. 02912
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Hejnol A. A twist in time--the evolution of spiral cleavage in the light of animal phylogeny. Integr Comp Biol 2010; 50:695-706. [PMID: 21558233 DOI: 10.1093/icb/icq103] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recent progress in reconstructing animal relationships enables us to draw a better picture of the evolution of important characters such as organ systems and developmental processes. By mapping these characters onto the phylogenetic framework, we can detect changes that have occurred in them during evolution. The spiral mode of development is a complex of characters that is present in many lineages, such as nemerteans, annelids, mollusks, and polyclad platyhelminthes. However, some of these lineages show variations of this general program in which sub-characters are modified without changing the overlying pattern. Recent molecular phylogenies suggest that spiral cleavage was lost, or at least has deviated from its original pattern, in more lineages than was previously thought (e.g., in rotifers, gastrotrichs, bryozoans, brachiopods, and phoronids). Here, I summarize recent progress in reconstructing the spiralian tree of life and discuss its significance for our understanding of the spiral-cleavage character complex. I conclude that more detailed knowledge of the development of spiralian taxa is necessary to understand the mechanisms behind these changes, and to understand the evolutionary changes and adaptations of spiralian embryos.
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Affiliation(s)
- Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, Thormøhlensgate 55, NO-5008, Bergen, Norway.
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Smith JM, Cridge AG, Dearden PK. Germ cell specification and ovary structure in the rotifer Brachionus plicatilis. EvoDevo 2010; 1:5. [PMID: 20849649 PMCID: PMC2938724 DOI: 10.1186/2041-9139-1-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 08/02/2010] [Indexed: 11/28/2022] Open
Abstract
Background The segregation of the germline from somatic tissues is an essential process in the development of all animals. Specification of the primordial germ cells (PGCs) takes place via different strategies across animal phyla; either specified early in embryogenesis by the inheritance of maternal determinants in the cytoplasm of the oocyte ('preformation') or selected later in embryonic development from undifferentiated precursors by a localized inductive signal ('epigenesis'). Here we investigate the specification and development of the germ cells in the rotifer Brachionus plicatilis, a member of the poorly-characterized superphyla Lophotrochozoa, by isolating the Brachionus homologues of the conserved germ cell markers vasa and nanos, and examining their expression using in situ hybridization. Results Bpvasa and Bpnos RNA expression have very similar distributions in the Brachionus ovary, showing ubiquitous expression in the vitellarium, with higher levels in the putative germ cell cluster. Bpvas RNA expression is present in freshly laid eggs, remaining ubiquitous in embryos until at least the 96 cell stage after which expression narrows to a small cluster of cells at the putative posterior of the embryo, consistent with the developing ovary. Bpnos RNA expression is also present in just-laid eggs but expression is much reduced by the four-cell stage and absent by the 16-cell stage. Shortly before hatching of the juvenile rotifer from the egg, Bpnos RNA expression is re-activated, located in a subset of posterior cells similar to those expressing Bpvas at the same stage. Conclusions The observed expression of vasa and nanos in the developing B. plicatilis embryo implies an epigenetic origin of primordial germ cells in Rotifer.
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Affiliation(s)
- James M Smith
- Laboratory for Evolution and Development, Genetics Otago and the National Research Centre for Growth and Development, Biochemistry Department, University of Otago, PO Box 56, Dunedin, Aotearoa-New Zealand.
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Henry JJ, Perry KJ, Fukui L, Alvi N. Differential localization of mRNAs during early development in the mollusc, Crepidula fornicata. Integr Comp Biol 2010; 50:720-33. [PMID: 21558235 DOI: 10.1093/icb/icq088] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Certain mRNAs have been shown to be segregated in different cells in various metazoan embryos. These events represent aspects of autonomous mechanisms that establish particular embryonic cell fates and axial properties associated with asymmetric cell divisions. The spiralian lophotrochozoans (which include molluscs, annelids, nemerteans, gnathostomulids, dicyemid mesozoans, entoprocts, and platyhelminthes) exhibit a highly conserved pattern of early development that involves stereotypical, asymmetric cell divisions (termed "spiral cleavage"). Recently, it was demonstrated that various mRNAs are dynamically localized to the centrosomes in specific cells during early development in the gastropod mollusc, Ilyanassa obsoleta. During subsequent cell divisions, these messages become segregated in particular daughter cells, and it has been proposed that these events distinguish the developmental potential of these cells within the early embryo of I. obsoleta. The molecular mechanisms underlying these events, however, are still unknown. Here we show for the first time in another spiralian lophotrochozoan (the gastropod Crepidula fornicata) that similar patterns of mRNA localization take place during early development. To characterize the transcriptome of early development, and identify candidate genes for the expression analyses, high-throughput sequencing was carried out, via GS FLX Titanium 454 pyrosequencing. The annotated sequences have been made available as a resource for the scientific community (www.life.illinoi.edu/henry/crepidula_databases.html). Presumably, specific proteins associated with centrosomes may be important for these mRNA localization events. In silico sequence comparisons with known centriolar/centrosomal, ciliary/basal body proteomes shows that a large number of those proteins are represented in the collection of expressed sequence tags of C. fornicata annotated in this study. These data should be useful for future studies of the role of specific mRNAs in controlling cell fate and axial specification in the spiralian Lophotrochozoa, and for dissecting the underlying molecular mechanisms that accomplish these events.
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Affiliation(s)
- Jonathan J Henry
- Department of Cell and Developmental Biology, University of Illinois, 601 S. Goodwin Ave., Urbana IL 61801, USA.
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Juliano CE, Yajima M, Wessel GM. Nanos functions to maintain the fate of the small micromere lineage in the sea urchin embryo. Dev Biol 2010; 337:220-32. [PMID: 19878662 PMCID: PMC2812692 DOI: 10.1016/j.ydbio.2009.10.030] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 10/09/2009] [Accepted: 10/21/2009] [Indexed: 11/16/2022]
Abstract
The translational regulator nanos is required for the survival and maintenance of primordial germ cells during embryogenesis. Three nanos homologs are present in the genome of the sea urchin Strongylocentrotus purpuratus, all of which are expressed with different timing in the small micromere lineage. This lineage is set-aside during embryogenesis and contributes to constructing the adult rudiment. Small micromeres lacking Sp-nanos1 and Sp-nanos2 undergo an extra division and are not incorporated into the coelomic pouches. Further, these cells do not accumulate Vasa protein even though they retain vasa mRNA. Larvae that develop from Sp-nanos1 and 2 knockdown embryos initially appear normal, but do not develop adult rudiments; although they are capable of eating, over time they fail to grow and eventually die. We conclude that the acquisition and maintenance of multipotency in the small micromere lineage requires nanos, which may function in part by repressing the cell cycle and regulating other multipotency factors such as vasa. This work, in combination with other recent results in Ilyanassa and Platynereis dumerilii, suggests the presence of a conserved molecular program underlying both primordial germ cell and multipotent cell specification and maintenance.
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Affiliation(s)
- Celina E Juliano
- Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting St., Providence, RI 02912, USA
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Abstract
The growth of daughter cells in budding yeast is a classic model for investigating mechanisms involved in asymmetric cell division. An unexpected collaboration between the DEAD-box protein Dbp5 and the nuclear transport receptor Kap104 controls localized protein synthesis at the bud tip during mitosis.
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Dill KK, Seaver EC. Vasa and nanos are coexpressed in somatic and germ line tissue from early embryonic cleavage stages through adulthood in the polychaete Capitella sp. I. Dev Genes Evol 2008; 218:453-63. [DOI: 10.1007/s00427-008-0236-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 06/16/2008] [Indexed: 11/28/2022]
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Nanos Is Required in Somatic Blast Cell Lineages in the Posterior of a Mollusk Embryo. Curr Biol 2008; 18:331-6. [DOI: 10.1016/j.cub.2008.01.055] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 01/17/2008] [Accepted: 01/21/2008] [Indexed: 11/20/2022]
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