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Cullen G, Gilligan JB, Guhlin JG, Dearden PK. Germline progenitors and oocyte production in the honeybee queen ovary. Genetics 2023; 225:iyad138. [PMID: 37487025 PMCID: PMC10471204 DOI: 10.1093/genetics/iyad138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/26/2023] Open
Abstract
Understanding the reproduction of honeybee queens is crucial to support populations of this economically important insect. Here we examine the structure of the honeybee ovary to determine the nature of the germline progenitors in the ovary. Using a panel of marker genes that mark somatic or germline tissue in other insects we determine which cells in the honeybee ovary are somatic and which germline. We examine patterns of cell division and demonstrate that, unlike Drosophila, there is no evidence of single germline stem cells that provide the germline in honeybees. Germline progenitors are clustered in groups of 8 cells, joined by a polyfusome, and collections of these, in each ovariole, appear to maintain the germline during reproduction. We also show that these 8-cell clusters can divide and that their division occurs such that the numbers of germline progenitors are relatively constant over the reproductive life of queen honeybees. This information helps us to understand the diversity of structures in insect reproduction, and provide information to better support honeybee reproduction.
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Affiliation(s)
- Georgia Cullen
- Laboratory for Evolution and Development, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
| | - Joshua B Gilligan
- Laboratory for Evolution and Development, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
- Biological Heritage National Science Challenge, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
| | - Joseph G Guhlin
- Laboratory for Evolution and Development, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
- Genomics Aotearoa, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
| | - Peter K Dearden
- Laboratory for Evolution and Development, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
- Biological Heritage National Science Challenge, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
- Genomics Aotearoa, Biochemistry Department, University of Otago, Dunedin, 9054, Aotearoa-New Zealand
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2
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Marescalchi O, Gargiulo G, Falconi R. Evidence of germline precursors in asexually reproducing Aeolosoma hemprichi and Aeolosoma viride (Annelida, Aeolosomatidae). INVERTEBR REPROD DEV 2020. [DOI: 10.1080/07924259.2019.1699610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ombretta Marescalchi
- Department of Biological, Geological and Environmental Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Giuseppe Gargiulo
- Department of Pharmacy, Biotechnology and Sport Science, Bologna, Italy
| | - Rosanna Falconi
- Department of Biological, Geological and Environmental Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy
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3
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Chung CY, Hsiao YM, Huang TY, Chang TH, Chang CC. Germline expression of the hunchback orthologues in the asexual viviparous aphids: a conserved feature within the Aphididae. INSECT MOLECULAR BIOLOGY 2018; 27:752-765. [PMID: 29892979 DOI: 10.1111/imb.12514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In animals, differentiation of germline from soma usually takes place during embryogenesis. Genes and their products that are preferentially expressed in the embryonic germ cells are regarded as candidates for maintaining germline fate or promoting germline identity. In Drosophila, for example, the protein encoded by the germline gene vasa is specifically restricted to the germ cells, while products of the gap gene hunchback (hb), a somatic gene, are preferentially expressed in the neuroblasts. In this study, we report the expression of both messenger RNA and protein encoded by Aphb, an hb orthologue in the asexual viviparous pea aphid Acyrthosiphon pisum, in germ cells as well as in neuroblasts. We infer that expression of Aphb messenger RNA in the germ cells during the formation of germaria is required for the anterior localization of Aphb in the protruding oocytes. Germarial expression and anterior localization of ApKrüppel was also identified but, unlike Aphb, its expression was not detected in the migrating germ cells. Very similar patterns of hb expression were also identified in the green peach aphid Myzus persicae, suggesting that germline expression of hb is conserved within the Aphididae. To date, this pattern of hb germline expression has not been reported in other insects.
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Affiliation(s)
- C-Y Chung
- Laboratory for Genetics and Development, Department of Entomology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
| | - Y-M Hsiao
- Laboratory for Genetics and Development, Department of Entomology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
- Institute of Biotechnology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - T-Y Huang
- Laboratory for Genetics and Development, Department of Entomology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - T-H Chang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan
| | - C-C Chang
- Laboratory for Genetics and Development, Department of Entomology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
- Institute of Biotechnology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan
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Nakao H, Takasu Y. Complexities in Bombyx germ cell formation process revealed by Bm-nosO (a Bombyx homolog of nanos) knockout. Dev Biol 2018; 445:29-36. [PMID: 30367845 DOI: 10.1016/j.ydbio.2018.10.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/11/2018] [Accepted: 10/17/2018] [Indexed: 11/25/2022]
Abstract
Inheritance (sequestration of a localized determinant: germplasm) and zygotic induction are two modes of metazoan primordial germ cell (PGC) specification. vasa and nanos homologs are evolutionarily conserved germline marker genes that have been used to examine the ontogeny of germ cells in various animals. In the lepidopteran insect Bombyx mori, although the lack of vasa homolog (BmVLG) protein localization as well as microscopic observation suggested the lack of germplasm, classical embryo manipulation studies and the localization pattern of Bm-nosO (one of the four nanos genes in Bombyx) maternal mRNA in the egg raised the possibility that an inheritance mode is operating in Bombyx. Here, we generated Bm-nosO knockouts to examine whether the localized mRNA acts as a localized germ cell determinant. Contrary to our expectations, Bm-nosO knockout lines could be established. However, these lines frequently produced abnormal eggs, which failed to hatch, to various extent depending on the individuals. We also found that Bm-nosO positively regulated BmVLG expression at least during embryonic stage, directly or indirectly, indicating that these genes were on the same developmental pathway for germ cell formation in Bombyx. These results suggest that these conserved genes are concerned with stable germ cell production. On the other hand, from the aspect of BmVLG as a PGC marker, we showed that maternal Bm-nosO product(s) as well as early zygotic Bm-nosO activity were redundantly involved in PGC specification; elimination of both maternal and zygotic gene activities (as in knockout lines) resulted in the apparent lack of PGCs, indicating that an inheritance mechanism indeed operates in Bombyx. This, however, together with the fact that germ cells are produced at all in Bm-nosO knockout lines, also suggests the possibility that, in Bombyx, not only this inheritance mechanism but also an inductive mechanism acts in concert to form germ cells or that loss of early PGCs are compensated for by germline regeneration: mechanisms that could enable the evolution of preformation. Thus, Bombyx could serve as an important organism in understanding the evolution of germ cell formation mechanisms; transition between preformation and inductive modes.
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Affiliation(s)
- Hajime Nakao
- Insect Genome Research and Engineering Unit, Division of Applied Genetics, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 1-2 Oowashi, Tsukuba, Ibaraki 305-8634, Japan.
| | - Yoko Takasu
- Silk Materials Research Unit, Division of Biotechnology, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), 1-2 Oowashi, Tsukuba, Ibaraki 305-8634, Japan
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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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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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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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Lynch JA, Ozüak O, Khila A, Abouheif E, Desplan C, Roth S. The phylogenetic origin of oskar coincided with the origin of maternally provisioned germ plasm and pole cells at the base of the Holometabola. PLoS Genet 2011; 7:e1002029. [PMID: 21552321 PMCID: PMC3084197 DOI: 10.1371/journal.pgen.1002029] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 02/02/2011] [Indexed: 12/19/2022] Open
Abstract
The establishment of the germline is a critical, yet surprisingly evolutionarily labile, event in the development of sexually reproducing animals. In the fly Drosophila, germ cells acquire their fate early during development through the inheritance of the germ plasm, a specialized maternal cytoplasm localized at the posterior pole of the oocyte. The gene oskar (osk) is both necessary and sufficient for assembling this substance. Both maternal germ plasm and oskar are evolutionary novelties within the insects, as the germline is specified by zygotic induction in basally branching insects, and osk has until now only been detected in dipterans. In order to understand the origin of these evolutionary novelties, we used comparative genomics, parental RNAi, and gene expression analyses in multiple insect species. We have found that the origin of osk and its role in specifying the germline coincided with the innovation of maternal germ plasm and pole cells at the base of the holometabolous insects and that losses of osk are correlated with changes in germline determination strategies within the Holometabola. Our results indicate that the invention of the novel gene osk was a key innovation that allowed the transition from the ancestral late zygotic mode of germline induction to a maternally controlled establishment of the germline found in many holometabolous insect species. We propose that the ancestral role of osk was to connect an upstream network ancestrally involved in mRNA localization and translational control to a downstream regulatory network ancestrally involved in executing the germ cell program.
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Affiliation(s)
- Jeremy A Lynch
- Institute for Developmental Biology, University of Cologne, Cologne, Germany.
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Nakamura T, Yoshizaki M, Ogawa S, Okamoto H, Shinmyo Y, Bando T, Ohuchi H, Noji S, Mito T. Imaging of transgenic cricket embryos reveals cell movements consistent with a syncytial patterning mechanism. Curr Biol 2010; 20:1641-7. [PMID: 20800488 DOI: 10.1016/j.cub.2010.07.044] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 07/29/2010] [Accepted: 07/29/2010] [Indexed: 11/16/2022]
Abstract
The mode of insect embryogenesis varies among species, reflecting adaptations to different life history strategies [1, 2]. In holometabolous insects, which include the model systems, such as the fruit fly and the red flour beetle, a large proportion of the blastoderm produces an embryo, whereas hemimetabolous embryos generally arise from a small region of the blastoderm [3]. Despite their importance in evolutionary studies, information of early developmental dynamics of hemimetabolous insects remains limited. Here, to clarify how maternal and gap gene products act in patterning the embryo of basal hemimetabolous insects, we analyzed the dynamic segmentation process in transgenic embryos of an intermediate-germ insect species, the cricket, Gryllus bimaculatus. Our data based on live imaging of fluorescently labeled embryonic cells and nuclei suggest that the positional specification of the cellular blastoderm may be established in the syncytium, where maternally derived gradients could act fundamentally in a way that is similar to that of Drosophila, namely throughout the egg. Then, the blastoderm cells move dynamically, retaining their positional information to form the posteriorly localized germ anlage. Furthermore, we find that the anterior head region of the cricket embryo is specified by orthodenticle in a cellular environment earlier than the gnathal and thoracic regions. Our findings imply that the syncytial mode of the early segmentation in long-germ insects evolved from a dynamic syncytial-to-cellular mode found in the present study, accompanied by a heterochronic shift of gap gene action.
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Affiliation(s)
- Taro Nakamura
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, Japan
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Evolution of insect development: to the hemimetabolous paradigm. Curr Opin Genet Dev 2010; 20:355-61. [PMID: 20462751 DOI: 10.1016/j.gde.2010.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 04/09/2010] [Accepted: 04/13/2010] [Indexed: 11/23/2022]
Abstract
Mechanisms of insect development have been extensively studied in Drosophila melanogaster, a holometabolous insect. However, recent studies on other insects have gradually revealed that there exist new developmental paradigms. In this review, we focus on the new hemimetabolous paradigm. We highlight how hemimetabolous short-germ or intermediate-germ embryos establish the anterior/posterior (A/P) pattern and the importance of dynamic cell movement during germband formation. In hemimetabolous insects, orthodenticle, encoding a homeodomain-containing transcription factor, and wingless/Wnt signaling could play crucial roles in the A/P pattern formation. We also discuss recent evidence suggesting that insect developmental modes may have evolved by heterochronic shifts, while retaining certain universal metazoan features.
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