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Zhang H, Goh FG, Ng LC, Chen CH, Cai Y. Aedes aegypti exhibits a distinctive mode of late ovarian development. BMC Biol 2023; 21:11. [PMID: 36690984 PMCID: PMC9872435 DOI: 10.1186/s12915-023-01511-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 01/05/2023] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Insects live in almost every habitat on earth. To adapt to their diverse environments, insects have developed a myriad of different strategies for reproduction reflected in diverse anatomical and behavioral features that the reproductive systems of females exhibit. Yet, ovarian development remains largely uncharacterized in most species except Drosophila melanogaster (D. melanogaster), a high Diptera model. In this study, we investigated the detailed developmental process of the ovary in Aedes aegypti (Ae. aegypti), a major vector of various disease-causing pathogens that inhabits tropical and subtropical regions. RESULTS Compared with Drosophila melanogaster, a model of higher Diptera, the processes of pole cell formation and gonad establishment during embryonic stage are highly conserved in Ae. aegypti. However, Ae. aegypti utilizes a distinct strategy to form functional ovaries during larval/pupal development. First, during larval stage, Ae. aegypti primordial germ cells (PGCs) undergo a cyst-like proliferation with synchronized divisions and incomplete cytokinesis, leading to the formation of one tightly packed "PGC mass" containing several interconnected cysts, different from D. melanogaster PGCs that divide individually. This cyst-like proliferation is regulated by the target of rapamycin (TOR) pathway upon nutritional status. Second, ecdysone-triggered ovariole formation during metamorphosis exhibits distinct events, including "PGC mass" breakdown, terminal filament cell degeneration, and pre-ovariole migration. These unique developmental features might explain the structural and behavioral differences between Aedes and Drosophila ovaries. Importantly, both cyst-like proliferation and distinct ovariole formation are also observed in Culex quinquefasciatus and Anopheles sinensis, suggesting a conserved mode of ovarian development among mosquito species. In comparison with Drosophila, the ovarian development in Aedes and other mosquitoes might represent a primitive mode in the lower Diptera. CONCLUSIONS Our study reveals a new mode of ovarian development in mosquitoes, providing insights into a better understanding of the reproductive system and evolutionary relationship among insects.
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Affiliation(s)
- Heng Zhang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
| | - Feng Guang Goh
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - Lee Ching Ng
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #06-05/08, Helios Block, Singapore, 138667, Singapore
| | - Chun Hong Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Miaoli, 350401, Taiwan
| | - Yu Cai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore.
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore.
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2
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Pacheco ID, Walling LL, Atkinson PW. Gene Editing and Genetic Control of Hemipteran Pests: Progress, Challenges and Perspectives. Front Bioeng Biotechnol 2022; 10:900785. [PMID: 35747496 PMCID: PMC9209771 DOI: 10.3389/fbioe.2022.900785] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/09/2022] [Indexed: 12/16/2022] Open
Abstract
The origin of the order Hemiptera can be traced to the late Permian Period more than 230 MYA, well before the origin of flowering plants 100 MY later in during the Cretaceous period. Hemipteran species consume their liquid diets using a sucking proboscis; for phytophagous hemipterans their mouthparts (stylets) are elegant structures that enable voracious feeding from plant xylem or phloem. This adaptation has resulted in some hemipteran species becoming globally significant pests of agriculture resulting in significant annual crop losses. Due to the reliance on chemical insecticides for the control of insect pests in agricultural settings, many hemipteran pests have evolved resistance to insecticides resulting in an urgent need to develop new, species-specific and environmentally friendly methods of pest control. The rapid advances in CRISPR/Cas9 technologies in model insects such as Drosophila melanogaster, Tribolium castaneum, Bombyx mori, and Aedes aegypti has spurred a new round of innovative genetic control strategies in the Diptera and Lepidoptera and an increased interest in assessing genetic control technologies for the Hemiptera. Genetic control approaches in the Hemiptera have, to date, been largely overlooked due to the problems of introducing genetic material into the germline of these insects. The high frequency of CRISPR-mediated mutagenesis in model insect species suggest that, if the delivery problem for Hemiptera could be solved, then gene editing in the Hemiptera might be quickly achieved. Significant advances in CRISPR/Cas9 editing have been realized in nine species of Hemiptera over the past 4 years. Here we review progress in the Hemiptera and discuss the challenges and opportunities for extending contemporary genetic control strategies into species in this agriculturally important insect orderr.
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Affiliation(s)
- Inaiara D. Pacheco
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
| | - Linda L. Walling
- Department of Botany & Plant Sciences, University of California, Riverside, Riverside, CA, United States
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, United States
| | - Peter W. Atkinson
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, United States
- *Correspondence: Peter W. Atkinson,
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3
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Kemph A, Lynch JA. Evolution of germ plasm assembly and function among the insects. CURRENT OPINION IN INSECT SCIENCE 2022; 50:100883. [PMID: 35123121 PMCID: PMC9133133 DOI: 10.1016/j.cois.2022.100883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/13/2022] [Accepted: 01/24/2022] [Indexed: 05/04/2023]
Abstract
Germ plasm is a substance capable of driving naive cells toward the germ cell fate. Germ plasm has had multiple independent origins, and takes on diverse forms and functions throughout animals, including in insects. We describe here recent advances in the understanding of the evolution of germ plasm in insects. A major theme that has emerged is the complex and convoluted interactions of germ plasm with symbiotic bacteria within the germline, including at the very origin of oskar, the gene required for assembling germ plasm in insects. Major advancements have also been made in understanding the basic molecular arrangement of germ plasm in insects. These advances demonstrate that further analysis of insect germ plasm will be fruitful in illuminating diverse aspects of evolutionary and developmental biology.
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Blondel L, Besse S, Rivard EL, Ylla G, Extavour CG. Evolution of a cytoplasmic determinant: evidence for the biochemical basis of functional evolution of the novel germ line regulator oskar. Mol Biol Evol 2021; 38:5491-5513. [PMID: 34550378 PMCID: PMC8662646 DOI: 10.1093/molbev/msab284] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Germ line specification is essential in sexually reproducing organisms. Despite their critical role, the evolutionary history of the genes that specify animal germ cells is heterogeneous and dynamic. In many insects, the gene oskar is required for the specification of the germ line. However, the germ line role of oskar is thought to be a derived role resulting from co-option from an ancestral somatic role. To address how evolutionary changes in protein sequence could have led to changes in the function of Oskar protein that enabled it to regulate germ line specification, we searched for oskar orthologs in 1,565 publicly available insect genomic and transcriptomic data sets. The earliest-diverging lineage in which we identified an oskar ortholog was the order Zygentoma (silverfish and firebrats), suggesting that oskar originated before the origin of winged insects. We noted some order-specific trends in oskar sequence evolution, including whole gene duplications, clade-specific losses, and rapid divergence. An alignment of all known 379 Oskar sequences revealed new highly conserved residues as candidates that promote dimerization of the LOTUS domain. Moreover, we identified regions of the OSK domain with conserved predicted RNA binding potential. Furthermore, we show that despite a low overall amino acid conservation, the LOTUS domain shows higher conservation of predicted secondary structure than the OSK domain. Finally, we suggest new key amino acids in the LOTUS domain that may be involved in the previously reported Oskar−Vasa physical interaction that is required for its germ line role.
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Affiliation(s)
- Leo Blondel
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Savandara Besse
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Emily L Rivard
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Guillem Ylla
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Cassandra G Extavour
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
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5
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A state-of-the-art review of surrogate propagation in fish. Theriogenology 2019; 133:216-227. [DOI: 10.1016/j.theriogenology.2019.03.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 03/30/2019] [Indexed: 12/20/2022]
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Bilinski SM, Jaglarz MK, Tworzydlo W. Organelle assemblages implicated in the transfer of oocyte components to the embryo: an insect perspective. CURRENT OPINION IN INSECT SCIENCE 2019; 31:1-7. [PMID: 31109662 DOI: 10.1016/j.cois.2018.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/09/2018] [Indexed: 06/09/2023]
Abstract
Besides reserve materials (yolk spheres, lipid droplets), ribosomes and various mRNA species, insect oocytes contain large easily morphologically recognizable organelle assemblages: the Balbiani body and the oosome (pole plasm). These assemblages are implicated in the transfer of oocyte components (mitochondria, polar granules) to the embryo that is to offspring. Here, we review present knowledge of morphology, morphogenesis, molecular composition and function/s of these assemblages. We discuss also the morphogenesis and presumed function of unconventional organelle assemblages, dormant stacks of endoplasmic reticulum, recently described in the oocytes and early embryos of a viviparous dermapteran, Hemimerus talpoides.
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Affiliation(s)
- Szczepan M Bilinski
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland.
| | - Mariusz K Jaglarz
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
| | - Waclaw Tworzydlo
- Department of Developmental Biology and Invertebrate Morphology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Krakow, Poland
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7
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Kulkarni A, Extavour CG. The Cricket Gryllus bimaculatus: Techniques for Quantitative and Functional Genetic Analyses of Cricket Biology. Results Probl Cell Differ 2019; 68:183-216. [PMID: 31598857 DOI: 10.1007/978-3-030-23459-1_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
All extant species are an outcome of nature's "experiments" during evolution, and hence multiple species need to be studied and compared to gain a thorough understanding of evolutionary processes. The field of evolutionary developmental biology (evo-devo) aspires to expand the number of species studied, because most functional genetic studies in animals have been limited to a small number of "traditional" model organisms, many of which belong to the same phylum (Chordata). The phylum Arthropoda, and particularly its component class Insecta, possesses many important characteristics that are considered favorable and attractive for evo-devo research, including an astonishing diversity of extant species and a wide disparity in body plans. The development of the most thoroughly investigated insect genetic model system to date, the fruit fly Drosophila melanogaster (a holometabolous insect), appears highly derived with respect to other insects and indeed with respect to most arthropods. In comparison, crickets (a basally branching hemimetabolous insect lineage compared to the Holometabola) are thought to embody many developmental features that make them more representative of insects. Here we focus on crickets as emerging models to study problems in a wide range of biological areas and summarize the currently available molecular, genomic, forward and reverse genetic, imaging and computational tool kit that has been established or adapted for cricket research. With an emphasis on the cricket species Gryllus bimaculatus, we highlight recent efforts made by the scientific community in establishing this species as a laboratory model for cellular biology and developmental genetics. This broad toolkit has the potential to accelerate many traditional areas of cricket research, including studies of adaptation, evolution, neuroethology, physiology, endocrinology, regeneration, and reproductive behavior. It may also help to establish newer areas, for example, the use of crickets as animal infection model systems and human food sources.
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Affiliation(s)
- Arpita Kulkarni
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
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8
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Krishnakumar P, Riemer S, Perera R, Lingner T, Goloborodko A, Khalifa H, Bontems F, Kaufholz F, El-Brolosy MA, Dosch R. Functional equivalence of germ plasm organizers. PLoS Genet 2018; 14:e1007696. [PMID: 30399145 PMCID: PMC6219760 DOI: 10.1371/journal.pgen.1007696] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/16/2018] [Indexed: 11/18/2022] Open
Abstract
The proteins Oskar (Osk) in Drosophila and Bucky ball (Buc) in zebrafish act as germ plasm organizers. Both proteins recapitulate germ plasm activities but seem to be unique to their animal groups. Here, we discover that Osk and Buc show similar activities during germ cell specification. Drosophila Osk induces additional PGCs in zebrafish. Surprisingly, Osk and Buc do not show homologous protein motifs that would explain their related function. Nonetheless, we detect that both proteins contain stretches of intrinsically disordered regions (IDRs), which seem to be involved in protein aggregation. IDRs are known to rapidly change their sequence during evolution, which might obscure biochemical interaction motifs. Indeed, we show that Buc binds to the known Oskar interactors Vasa protein and nanos mRNA indicating conserved biochemical activities. These data provide a molecular framework for two proteins with unrelated sequence but with equivalent function to assemble a conserved core-complex nucleating germ plasm. Multicellular organisms use gametes for their propagation. Gametes are formed from germ cells, which are specified during embryogenesis in some animals by the inheritance of RNP granules known as germ plasm. Transplantation of germ plasm induces extra germ cells, whereas germ plasm ablation leads to the loss of gametes and sterility. Therefore, germ plasm is key for germ cell formation and reproduction. However, the molecular mechanisms of germ cell specification by germ plasm in the vertebrate embryo remain an unsolved question. Proteins, which assemble the germ plasm, are known as germ plasm organizers. Here, we show that the two germ plasm organizers Oskar from the fly and Bucky ball from the fish show similar functions by using a cross species approach. Both are intrinsically disordered proteins, which rapidly changed their sequence during evolution. Moreover, both proteins still interact with conserved components of the germ cell specification pathway. These data might provide a first example of two proteins with the same biological role, but distinct sequence.
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Affiliation(s)
- Pritesh Krishnakumar
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Stephan Riemer
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Roshan Perera
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Thomas Lingner
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Alexander Goloborodko
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Hazem Khalifa
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Franck Bontems
- Laboratory of Metabolism, Department of Internal Medicine Specialties, Faculty of Medicine, University of Geneva, Switzerland
| | - Felix Kaufholz
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Mohamed A. El-Brolosy
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
| | - Roland Dosch
- Institute for Developmental Biochemistry, University Medical Center, Göttingen, Germany
- Institute of Human Genetics, University Medical Center, Göttingen, Germany
- * E-mail:
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9
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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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10
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Bilinski SM, Jaglarz MK, Tworzydlo W. The Pole (Germ) Plasm in Insect Oocytes. Results Probl Cell Differ 2017; 63:103-126. [PMID: 28779315 DOI: 10.1007/978-3-319-60855-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Animal germline cells are specified either through zygotic induction or cytoplasmic inheritance. Zygotic induction takes place in mid- or late embryogenesis and requires cell-to-cell signaling leading to the acquisition of germline fate de novo. In contrast, cytoplasmic inheritance involves formation of a specific, asymmetrically localized oocyte region, termed the germ (pole) plasm. This region contains maternally provided germline determinants (mRNAs, proteins) that are capable of inducing germline fate in a subset of embryonic cells. Recent data indicate that among insects, the zygotic induction represents an ancestral condition, while the cytoplasmic inheritance evolved at the base of Holometabola or in the last common ancestor of Holometabola and its sister taxon, Paraneoptera.In this chapter, we first describe subsequent stages of morphogenesis of the pole plasm and polar granules in the model organism, Drosophila melanogaster. Then, we present an overview of morphology and cytoarchitecture of the pole plasm in various holometabolan and paraneopteran insect species. Finally, we focus on phylogenetic hypotheses explaining the known distribution of two different strategies of germline specification among insects.
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Affiliation(s)
- Szczepan M Bilinski
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland.
| | - Mariusz K Jaglarz
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
| | - Waclaw Tworzydlo
- Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387, Krakow, Poland
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11
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Kulkarni A, Extavour CG. Convergent evolution of germ granule nucleators: A hypothesis. Stem Cell Res 2017; 24:188-194. [PMID: 28801028 DOI: 10.1016/j.scr.2017.07.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/18/2017] [Accepted: 07/15/2017] [Indexed: 11/26/2022] Open
Abstract
Germ cells have been considered "the ultimate stem cell" because they alone, during normal development of sexually reproducing organisms, are able to give rise to all organismal cell types. Morphological descriptions of a specialized cytoplasm termed 'germ plasm' and associated electron dense ribonucleoprotein (RNP) structures called 'germ granules' within germ cells date back as early as the 1800s. Both germ plasm and germ granules are implicated in germ line specification across metazoans. However, at a molecular level, little is currently understood about the molecular mechanisms that assemble these entities in germ cells. The discovery that in some animals, the gene products of a small number of lineage-specific genes initiate the assembly (also termed nucleation) of germ granules and/or germ plasm is the first step towards facilitating a better understanding of these complex biological processes. Here, we draw on research spanning over 100years that supports the hypothesis that these nucleator genes may have evolved convergently, allowing them to perform analogous roles across animal lineages.
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Affiliation(s)
- Arpita Kulkarni
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
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