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Yamashita T, Ohde T, Nakamura T, Ishimaru Y, Watanabe T, Tomonari S, Nakamura Y, Noji S, Mito T. Involvement of the scalloped gene in morphogenesis of the wing margin via regulating cell growth in a hemimetabolous insect Gryllus bimaculatus. Dev Growth Differ 2023; 65:348-359. [PMID: 37310211 DOI: 10.1111/dgd.12869] [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: 12/22/2022] [Revised: 05/30/2023] [Accepted: 06/02/2023] [Indexed: 06/14/2023]
Abstract
The acquisition of wings was a key event in insect evolution. As hemimetabolous insects were the first group to acquire functional wings, establishing the mechanisms of wing formation in this group could provide useful insights into their evolution. In this study, we aimed to elucidate the expression and function of the gene scalloped (sd), which is involved in wing formation in Drosophila melanogaster, and in Gryllus bimaculatus mainly during postembryonic development. Expression analysis showed that sd is expressed in the tergal edge, legs, antennae, labrum, and cerci during embryogenesis and in the distal margin of the wing pads from at least the sixth instar in the mid to late stages. Because sd knockout caused early lethality, nymphal RNA interference experiments were performed. Malformations were observed in the wings, ovipositor, and antennae. By analyzing the effects on wing morphology, it was revealed that sd is mainly involved in the formation of the margin, possibly through the regulation of cell proliferation. In conclusion, sd might regulate the local growth of wing pads and influence wing margin morphology in Gryllus.
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Grants
- 17H03945 Ministry of Education, Culture, Sports, Science and Technology
- 19H02970 Ministry of Education, Culture, Sports, Science and Technology
- 19K06691 Ministry of Education, Culture, Sports, Science and Technology
- 20K21436 Ministry of Education, Culture, Sports, Science and Technology
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Affiliation(s)
- Takahisa Yamashita
- Graduate School of Advanced Technology and Science, Tokushima University, Tokushima, Japan
| | - Takahiro Ohde
- Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Taro Nakamura
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Yoshiyasu Ishimaru
- Graduate School of Sciences and Technology for Innovation, Tokushima University, Tokushima, Japan
| | - Takahito Watanabe
- Bio-Innovation Research Center, Tokushima University, Tokushima, Japan
| | - Sayuri Tomonari
- Technical Support Department, Tokushima University, Tokushima, Japan
| | - Yuki Nakamura
- Graduate School of Advanced Technology and Science, Tokushima University, Tokushima, Japan
| | - Sumihare Noji
- Bio-Innovation Research Center, Tokushima University, Tokushima, Japan
| | - Taro Mito
- Bio-Innovation Research Center, Tokushima University, Tokushima, Japan
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Gonzalez CJ, Hildebrandt TR, O'Donnell B. Characterizing Hox genes in mayflies (Ephemeroptera), with Hexagenia limbata as a new mayfly model. EvoDevo 2022; 13:15. [PMID: 35897030 PMCID: PMC9331126 DOI: 10.1186/s13227-022-00200-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 06/28/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hox genes are key regulators of appendage development in the insect body plan. The body plan of mayfly (Ephemeroptera) nymphs differs due to the presence of abdominal appendages called gills. Despite mayflies' phylogenetic position in Paleoptera and novel morphology amongst insects, little is known of their developmental genetics, such as the appendage-regulating Hox genes. To address this issue we present an annotated, early instar transcriptome and embryonic expression profiles for Antennapedia, Ultrabithorax, and Abdominal A proteins in the mayfly Hexagenia limbata, identify putative Hox protein sequences in the mayflies H. limbata, Cloeon dipterum, and Ephemera danica, and describe the genomic organization of the Hox gene cluster in E. danica. RESULTS Transcriptomic sequencing of early instar H. limbata nymphs yielded a high-quality assembly of 83,795 contigs, of which 22,975 were annotated against Folsomia candida, Nilaparvata lugens, Zootermopsis nevadensis and UniRef90 protein databases. Homeodomain protein phylogeny and peptide annotations identified coding sequences for eight of the ten canonical Hox genes (excluding zerknüllt/Hox3 and fushi tarazu) in H. limbata and C. dipterum, and all ten in E. danica. Mayfly Hox protein sequences and embryonic expression patterns of Antp, Ubx, and Abd-A appear highly conserved with those seen in other non-holometabolan insects. Similarly, the genomic organization of the Hox cluster in E. danica resembles that seen in most insects. CONCLUSIONS We present evidence that mayfly Hox peptide sequences and the embryonic expression patterns for Antp, Ubx, and Abd-A are extensively conserved with other insects, as is organization of the mayfly Hox gene cluster. The protein data suggest mayfly Antp, Ubx, and Abd-A play appendage promoting and repressing roles during embryogenesis in the thorax and abdomen, respectively, as in other insects. The identified expression of eight Hox genes, including Ubx and abd-A, in early instar nymphs further indicates a post-embryonic role, possibly in gill development. These data provide a basis for H. limbata as a complementary Ephemeridae model to the growing repertoire of mayfly model species and molecular techniques.
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Affiliation(s)
| | - Tobias R Hildebrandt
- Computational and Applied Mathematic Science, Plymouth State University, Plymouth, NH, USA
| | - Brigid O'Donnell
- Biological Sciences, Plymouth State University, Plymouth, NH, USA
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3
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Konopová B, Buchberger E, Crisp A. Transcriptome of pleuropodia from locust embryos supports that these organs produce enzymes enabling the larva to hatch. Front Zool 2020; 17:4. [PMID: 31969926 PMCID: PMC6966819 DOI: 10.1186/s12983-019-0349-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/23/2019] [Indexed: 01/02/2023] Open
Abstract
Background Pleuropodia are limb-derived glandular organs that transiently appear on the first abdominal segment in embryos of insects from majority of “orders”. They are missing in the genetic model Drosophila and little is known about them. Experiments carried out on orthopteran insects 80 years ago indicated that the pleuropodia secrete a “hatching enzyme” that digests the serosal cuticle to enable the larva to hatch, but evidence by state-of-the-art molecular methods is missing. Results We used high-throughput RNA-sequencing to identify the genes expressed in the pleuropodia of the locust Schistocerca gregaria (Orthoptera). First, using transmission electron microscopy we studied the development of the pleuropodia during 11 stages of the locust embryogenesis. We show that the glandular cells differentiate and start secreting just before the definitive dorsal closure of the embryo and the secretion granules outside the cells become more abundant prior to hatching. Next, we generated a comprehensive embryonic reference transcriptome for the locust and used it to study genome wide gene expression across ten morphologicaly defined stages of the pleuropodia. We show that when the pleuropodia have morphological markers of functional organs and produce secretion, they are primarily enriched in transcripts associated with transport functions. They express genes encoding enzymes capable of digesting cuticular protein and chitin. These include the potent cuticulo-lytic Chitinase 5, whose transcript rises just before hatching. Unexpected finding was the enrichment in transcripts for immunity-related enzymes. This indicates that the pleuropodia are equipped with epithelial immunity similarly as barrier epithelia in postembryonic stages. Conclusions These data provide transcriptomic support for the historic hypothesis that pleuropodia produce cuticle-degrading enzymes and function in hatching. They may also have other functions, such as facilitation of embryonic immune defense. By the genes that they express the pleuropodia are specialized embryonic organs and apparently an important though neglected part of insect physiology.
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Affiliation(s)
- Barbora Konopová
- 1Department of Zoology, University of Cambridge, Cambridge, UK.,2Department of Evolutionary Developmental Genetics, University of Göttingen, Göttingen, Germany.,Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Elisa Buchberger
- 4Department of Developmental Biology, University of Göttingen, Göttingen, Germany
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4
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Hox genes limit germ cell formation in the short germ insect Gryllus bimaculatus. Proc Natl Acad Sci U S A 2019; 116:16430-16435. [PMID: 31346080 DOI: 10.1073/pnas.1816024116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hox genes are conserved transcription factor-encoding genes that specify the identity of body regions in bilaterally symmetrical animals. In the cricket Gryllus bimaculatus, a member of the hemimetabolous insect group Orthoptera, the induction of a subset of mesodermal cells to form the primordial germ cells (PGCs) is restricted to the second through the fourth abdominal segments (A2 to A4). In numerous insect species, the Hox genes Sex-combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx), and abdominal-A (abd-A) jointly regulate the identities of middle and posterior body segments, suggesting that these genes may restrict PGC formation to specific abdominal segments in G. bimaculatus Here we show that reducing transcript levels of some or all of these Hox genes results in supernumerary and/or ectopic PGCs, either individually or in segment-specific combinations, suggesting that the role of these Hox genes is to limit PGC development with respect to their number, segmental location, or both. These data provide evidence of a role for this ancient group of genes in PGC development.
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Bidau CJ, Martínez PA. Evolutionary negative allometry of orthopteran hind femur length is a general phenomenon. ZOOMORPHOLOGY 2018. [DOI: 10.1007/s00435-018-0395-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Haug JT, Labandeira CC, Santiago-Blay JA, Haug C, Brown S. Life habits, hox genes, and affinities of a 311 million-year-old holometabolan larva. BMC Evol Biol 2015; 15:208. [PMID: 26416251 PMCID: PMC4587847 DOI: 10.1186/s12862-015-0428-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/03/2015] [Indexed: 01/01/2023] Open
Abstract
Background Holometabolous insects are the most diverse, speciose and ubiquitous group of multicellular organisms in terrestrial and freshwater ecosystems. The enormous evolutionary and ecological success of Holometabola has been attributed to their unique postembryonic life phases in which nonreproductive and wingless larvae differ significantly in morphology and life habits from their reproductive and mostly winged adults, separated by a resting stage, the pupa. Little is known of the evolutionary developmental mechanisms that produced the holometabolous larval condition and their Paleozoic origin based on fossils and phylogeny. Results We provide a detailed anatomic description of a 311 million-year-old specimen, the oldest known holometabolous larva, from the Mazon Creek deposits of Illinois, U.S.A. The head is ovoidal, downwardly oriented, broadly attached to the anterior thorax, and bears possible simple eyes and antennae with insertions encircled by molting sutures; other sutures are present but often indistinct. Mouthparts are generalized, consisting of five recognizable segments: a clypeo-labral complex, mandibles, possible hypopharynx, a maxilla bearing indistinct palp-like appendages, and labium. Distinctive mandibles are robust, triangular, and dicondylic. The thorax is delineated into three, nonoverlapping regions of distinctive surface texture, each with legs of seven elements, the terminal-most bearing paired claws. The abdomen has ten segments deployed in register with overlapping tergites; the penultimate segment bears a paired, cercus-like structure. The anterior eight segments bear clawless leglets more diminutive than the thoracic legs in length and cross-sectional diameter, and inserted more ventrolaterally than ventrally on the abdominal sidewall. Conclusions Srokalarva berthei occurred in an evolutionary developmental context likely responsible for the early macroevolutionary success of holometabolous insects. Srokalarva berthei bore head and prothoracic structures, leglet series on successive abdominal segments – in addition to comparable features on a second taxon eight million-years-younger – that indicates Hox-gene regulation of segmental and appendage patterning among earliest Holometabola. Srokalarva berthei body features suggest a caterpillar-like body plan and head structures indicating herbivory consistent with known, contemporaneous insect feeding damage on seed plants. Taxonomic resolution places Srokalarva berthei as an extinct lineage, apparently possessing features closer to neuropteroid than other holometabolous lineages. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0428-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joachim T Haug
- Ludwig Maximilians University Munich, Biocenter - Department of Biology II and GeoBio-Center, Großhaderner Str. 2, Planegg-Martinsried, 82152, Germany
| | - Conrad C Labandeira
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC, 20013, USA. .,Department of Entomology, University of Maryland, College Park, MD, 20742, USA. .,College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Jorge A Santiago-Blay
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC, 20013, USA.,Department of Crop and Agroenvironmental Sciences, University of Puerto Rico, Mayagüez, PR, 00681, USA
| | - Carolin Haug
- Ludwig Maximilians University Munich, Biocenter - Department of Biology II and GeoBio-Center, Großhaderner Str. 2, Planegg-Martinsried, 82152, Germany
| | - Susan Brown
- Division of Biology, Kansas State University, Manhattan, KS, 66502, USA
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Matsuoka Y, Bando T, Watanabe T, Ishimaru Y, Noji S, Popadić A, Mito T. Short germ insects utilize both the ancestral and derived mode of Polycomb group-mediated epigenetic silencing of Hox genes. Biol Open 2015; 4:702-9. [PMID: 25948756 PMCID: PMC4467190 DOI: 10.1242/bio.201411064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In insect species that undergo long germ segmentation, such as Drosophila, all segments are specified simultaneously at the early blastoderm stage. As embryogenesis progresses, the expression boundaries of Hox genes are established by repression of gap genes, which is subsequently replaced by Polycomb group (PcG) silencing. At present, however, it is not known whether patterning occurs this way in a more ancestral (short germ) mode of embryogenesis, where segments are added gradually during posterior elongation. In this study, two members of the PcG family, Enhancer of zeste (E(z)) and Suppressor of zeste 12 (Su(z)12), were analyzed in the short germ cricket, Gryllus bimaculatus. Results suggest that although stepwise negative regulation by gap and PcG genes is present in anterior members of the Hox cluster, it does not account for regulation of two posterior Hox genes, abdominal-A (abd-A) and Abdominal-B (Abd-B). Instead, abd-A and Abd-B are predominantly regulated by PcG genes, which is the mode present in vertebrates. These findings suggest that an intriguing transition of the PcG-mediated silencing of Hox genes may have occurred during animal evolution. The ancestral bilaterian state may have resembled the current vertebrate mode of regulation, where PcG-mediated silencing of Hox genes occurs before their expression is initiated and is responsible for the establishment of individual expression domains. Then, during insect evolution, the repression by transcription factors may have been acquired in anterior Hox genes of short germ insects, while PcG silencing was maintained in posterior Hox genes.
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Affiliation(s)
- Yuji Matsuoka
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8506, Japan
| | - Tetsuya Bando
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8506, Japan Present address: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama city, Okayama, 700-8530, Japan
| | - Takahito Watanabe
- Center for Collaboration among Agriculture, Industry and Commerce, The University of Tokushima, 2-24 Shinkura-cho, Tokushima City, Tokushima 770-8501, Japan
| | - Yoshiyasu Ishimaru
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8506, Japan
| | - Sumihare Noji
- Center for Collaboration among Agriculture, Industry and Commerce, The University of Tokushima, 2-24 Shinkura-cho, Tokushima City, Tokushima 770-8501, Japan
| | - Aleksandar Popadić
- Biological Sciences Department, Wayne State University, Detroit, MI 48202, USA
| | - Taro Mito
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima Graduate School, 2-1 Minami-Jyosanjima-cho, Tokushima City, Tokushima 770-8506, Japan
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Donoughe S, Extavour CG. Embryonic development of the cricket Gryllus bimaculatus. Dev Biol 2015; 411:140-56. [PMID: 25907229 DOI: 10.1016/j.ydbio.2015.04.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 04/10/2015] [Accepted: 04/11/2015] [Indexed: 12/22/2022]
Abstract
Extensive research into Drosophila melanogaster embryogenesis has improved our understanding of insect developmental mechanisms. However, Drosophila development is thought to be highly divergent from that of the ancestral insect and arthropod in many respects. We therefore need alternative models for arthopod development that are likely to be more representative of basally-branching clades. The cricket Gryllus bimaculatus is such a model, and currently has the most sophisticated functional genetic toolkit of any hemimetabolous insect. The existing cricket embryonic staging system is fragmentary, and it is based on morphological landmarks that are not easily visible on a live, undissected egg. To address this problem, here we present a complementary set of "egg stages" that serve as a guide for identifying the developmental progress of a cricket embryo from fertilization to hatching, based solely on the external appearance of the egg. These stages were characterized using a combination of brightfield timelapse microscopy, timed brightfield micrographs, confocal microscopy, and measurements of egg dimensions. These egg stages are particularly useful in experiments that involve egg injection (including RNA interference, targeted genome modification, and transgenesis), as injection can alter the speed of development, even in control treatments. We also use 3D reconstructions of fixed embryo preparations to provide a comprehensive description of the morphogenesis and anatomy of the cricket embryo during embryonic rudiment assembly, germ band formation, elongation, segmentation, and appendage formation. Finally, we aggregate and schematize a variety of published developmental gene expression patterns. This work will facilitate further studies on G. bimaculatus development, and serve as a useful point of reference for other studies of wild type and experimentally manipulated insect development in fields from evo-devo to disease vector and pest management.
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Affiliation(s)
- Seth Donoughe
- Department of Organismic & Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, United States
| | - Cassandra G Extavour
- Department of Organismic & Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, United States; Department of Molecular & Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, United States.
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9
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Mito T, Shinmyo Y, Kurita K, Nakamura T, Ohuchi H, Noji S. Ancestral functions of Delta/Notch signaling in the formation of body and leg segments in the cricket Gryllus bimaculatus. Development 2011; 138:3823-33. [DOI: 10.1242/dev.060681] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Delta/Notch signaling controls a wide spectrum of developmental processes, including body and leg segmentation in arthropods. The various functions of Delta/Notch signaling vary among species. For instance, in Cupiennius spiders, Delta/Notch signaling is essential for body and leg segmentation, whereas in Drosophila fruit flies it is involved in leg segmentation but not body segmentation. Therefore, to gain further insight into the functional evolution of Delta/Notch signaling in arthropod body and leg segmentation, we analyzed the function of the Delta (Gb′Delta) and Notch (Gb′Notch) genes in the hemimetabolous, intermediate-germ cricket Gryllus bimaculatus. We found that Gb′Delta and Gb′Notch were expressed in developing legs, and that RNAi silencing of Gb′Notch resulted in a marked reduction in leg length with a loss of joints. Our results suggest that the role of Notch signaling in leg segmentation is conserved in hemimetabolous insects. Furthermore, we found that Gb′Delta was expressed transiently in the posterior growth zone of the germband and in segmental stripes earlier than the appearance of wingless segmental stripes, whereas Gb′Notch was uniformly expressed in early germbands. RNAi knockdown of Gb′Delta or Gb′Notch expression resulted in malformation in body segments and a loss of posterior segments, the latter probably due to a defect in posterior growth. Therefore, in the cricket, Delta/Notch signaling might be required for proper morphogenesis of body segments and posterior elongation, but not for specification of segment boundaries.
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Affiliation(s)
- Taro Mito
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
| | - Yohei Shinmyo
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
| | - Kazuki Kurita
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
| | - Taro Nakamura
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
| | - Hideyo Ohuchi
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
| | - Sumihare Noji
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, 770-8506 Japan
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10
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Turchyn N, Chesebro J, Hrycaj S, Couso JP, Popadić A. Evolution of nubbin function in hemimetabolous and holometabolous insect appendages. Dev Biol 2011; 357:83-95. [PMID: 21708143 DOI: 10.1016/j.ydbio.2011.06.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 06/10/2011] [Accepted: 06/11/2011] [Indexed: 10/18/2022]
Abstract
Insects display a whole spectrum of morphological diversity, which is especially noticeable in the organization of their appendages. A recent study in a hemipteran, Oncopeltus fasciatus (milkweed bug), showed that nubbin (nub) affects antenna morphogenesis, labial patterning, the length of the femoral segment in legs, and the formation of a limbless abdomen. To further determine the role of this gene in the evolution of insect morphology, we analyzed its functions in two additional hemimetabolous species, Acheta domesticus (house cricket) and Periplaneta americana (cockroach), and re-examined its role in Drosophila melanogaster (fruit fly). While both Acheta and Periplaneta nub-RNAi first nymphs develop crooked antennae, no visible changes are observed in the morphologies of their mouthparts and abdomen. Instead, the main effect is seen in legs. The joint between the tibia and first tarsomere (Ta-1) is lost in Acheta, which in turn, causes a fusion of these two segments and creates a chimeric nub-RNAi tibia-tarsus that retains a tibial identity in its proximal half and acquires a Ta-1 identity in its distal half. Similarly, our re-analysis of nub function in Drosophila reveals that legs lack all true joints and the fly tibia also exhibits a fused tibia and tarsus. Finally, we observe a similar phenotype in Periplaneta except that it encompasses different joints (coxa-trochanter and femur-tibia), and in this species we also show that nub expression in the legs is regulated by Notch signaling, as had previously been reported in flies and spiders. Overall, we propose that nub acts downstream of Notch on the distal part of insect leg segments to promote their development and growth, which in turn is required for joint formation. Our data represent the first functional evidence defining a role for nub in leg segmentation and highlight the varying degrees of its involvement in this process across insects.
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Affiliation(s)
- Nataliya Turchyn
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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Hsia CC, Paré AC, Hannon M, Ronshaugen M, McGinnis W. Silencing of an abdominal Hox gene during early development is correlated with limb development in a crustacean trunk. Evol Dev 2010; 12:131-43. [PMID: 20433454 DOI: 10.1111/j.1525-142x.2010.00399.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We tested whether Artemia abd-A could repress limbs in Drosophila embryos, and found that although abd-A transcripts were produced, ABD-A protein was not. Similarly, developing Artemia epidermal cells showed expression of abd-A transcripts without accumulation of ABD-A protein. This finding in Artemia reveals a new variation in Hox gene function that is associated with morphological evolution. In this case, a HOX protein expression pattern is completely absent during early development, although the HOX protein is expressed at later stages in the central nervous system in a "homeotic-like" pattern. The combination of an absence of ABD-A protein expression in the Artemia limb primordia and the weak repressive function of Artemia UBX protein on the limb-promoting gene Dll are likely to be two reasons why homonomous limbs develop throughout the entire Artemia trunk.
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Affiliation(s)
- Cheryl C Hsia
- Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
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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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Hrycaj S, Chesebro J, Popadić A. Functional analysis of Scr during embryonic and post-embryonic development in the cockroach, Periplaneta americana. Dev Biol 2010; 341:324-34. [PMID: 20171962 DOI: 10.1016/j.ydbio.2010.02.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
The cockroach, Periplaneta americana represents a basal insect lineage that undergoes the ancestral hemimetabolous mode of development. Here, we examine the embryonic and post-embryonic functions of the hox gene Scr in Periplaneta as a way of better understanding the roles of this gene in the evolution of insect body plans. During embryogenesis, Scr function is strictly limited to the head with no role in the prothorax. This indicates that the ancestral embryonic function of Scr was likely restricted to the head, and that the posterior expansion of expression in the T1 legs may have preceded any apparent gain of function during evolution. In addition, Scr plays a pivotal role in the formation of the dorsal ridge, a structure that separates the head and thorax in all insects. This is evidenced by the presence of a supernumerary segment that occurs between the labial and T1 segments of RNAiScr first nymphs and is attributed to an alteration in engrailed (en) expression. The fact that similar Scr phenotypes are observed in Tribolium but not in Drosophila or Oncopeltus reveals the presence of lineage-specific variation in the genetic architecture that controls the formation of the dorsal ridge. In direct contrast to the embryonic roles, Scr has no function in the head region during post-embryogenesis in Periplaneta, and instead, strictly acts to provide identity to the T1 segment. Furthermore, the strongest Periplaneta RNAiScr phenotypes develop ectopic wing-like tissue that originates from the posterior region of the prothoracic segment. This finding provides a novel insight into the current debate on the morphological origin of insect wings.
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Affiliation(s)
- Steven Hrycaj
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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Mito T, Noji S. The Two-Spotted Cricket Gryllus bimaculatus: An Emerging Model for Developmental and Regeneration Studies. ACTA ACUST UNITED AC 2008; 2008:pdb.emo110. [PMID: 21356736 DOI: 10.1101/pdb.emo110] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTIONThe two-spotted cricket Gryllus bimaculatus De Geer (Orthoptera: Gryllidae), which is one of the most abundant cricket species, inhabits the tropical and subtropical regions of Asia, Africa, and Europe. G. bimaculatus can be easily bred in the laboratory and has been widely used to study insect physiology and neurobiology. Recently, this species has become established as a model animal for studies on molecular mechanisms of development and regeneration because its mode of development is more typical of arthropods than that of Drosophila melanogaster, and the cricket is probably ancestral for this phylum. Moreover, the cricket is a hemimetabolous insect, in which nymphs possess functional legs with a remarkable capacity for regeneration after damage. Because RNA interference (RNAi) works effectively in this species, the elucidation of mechanisms of development and regeneration has been expedited through loss-of-function analyses of genes. Furthermore, because RNAi-based techniques for analyzing gene functions can be combined with assay systems in other research areas (such as behavioral analyses), G. bimaculatus is expected to become a model organism in various fields of biology. Thus, it may be possible to establish the cricket as a simple model system for exploring more complex organisms such as humans.
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Affiliation(s)
- Taro Mito
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, Tokushima 770-8506, Japan
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15
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EGFR signaling is required for re-establishing the proximodistal axis during distal leg regeneration in the cricket Gryllus bimaculatus nymph. Dev Biol 2008; 319:46-55. [DOI: 10.1016/j.ydbio.2008.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 04/01/2008] [Accepted: 04/02/2008] [Indexed: 11/21/2022]
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Mito T, Nakamura T, Sarashina I, Chang CC, Ogawa S, Ohuchi H, Noji S. Dynamic expression patterns of vasa during embryogenesis in the cricket Gryllus bimaculatus. Dev Genes Evol 2008; 218:381-7. [PMID: 18542998 DOI: 10.1007/s00427-008-0226-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Accepted: 05/09/2008] [Indexed: 11/29/2022]
Abstract
The specification of germ cells during embryogenesis is an important issue in the development of metazoans. In insects, the mode of germ cell specification appears to be highly variable among species and molecular data are not sufficient to provide an evolutionary perspective to this issue. Expression of vasa can be used as a germ line marker. Here, we report the isolation of a vasa-like gene in a hemimetabolous insect, the cricket Gryllus bimaculatus (Gb'vas), and its expression patterns during oogenesis and embryogenesis. Gb'vas is preferentially expressed in the germarium and the expression of Gb'vas is detectable throughout vitellogenesis including mature eggs subjected to oviposition, suggesting that Gb'vas is maternally contributed to the cricket eggs. The zygotic expression of Gb'vas appears to start at the mid blastoderm stage in the posterior region of the egg, expanding in a developing germ anlage. In early germbands, an intense expression of Gb'vas is restricted to the posterior end. In later embryos, Gb'vas expression extends over the whole body and then distinctly localized to the embryonic gonad at the stage immediately before hatching. These results suggest that, in the cricket, germ cells are specified early in development at the posterior end of an early germband, as proposed by Heymons (1895) based on cytological criteria.
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Affiliation(s)
- Taro Mito
- Department of Life Systems, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City, Japan
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Antenna and all gnathal appendages are similarly transformed by homothorax knock-down in the cricket Gryllus bimaculatus. Dev Biol 2008; 313:80-92. [DOI: 10.1016/j.ydbio.2007.09.059] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2007] [Revised: 09/23/2007] [Accepted: 09/26/2007] [Indexed: 11/23/2022]
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Meinhardt H. Models of Biological Pattern Formation: From Elementary Steps to the Organization of Embryonic Axes. Curr Top Dev Biol 2008; 81:1-63. [DOI: 10.1016/s0070-2153(07)81001-5] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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19
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Divergent and conserved roles of extradenticle in body segmentation and appendage formation, respectively, in the cricket Gryllus bimaculatus. Dev Biol 2008; 313:67-79. [DOI: 10.1016/j.ydbio.2007.09.060] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 09/19/2007] [Accepted: 09/26/2007] [Indexed: 11/19/2022]
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Mahfooz N, Turchyn N, Mihajlovic M, Hrycaj S, Popadić A. Ubx regulates differential enlargement and diversification of insect hind legs. PLoS One 2007; 2:e866. [PMID: 17848997 PMCID: PMC1959121 DOI: 10.1371/journal.pone.0000866] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 08/20/2007] [Indexed: 11/21/2022] Open
Abstract
Differential enlargement of hind (T3) legs represents one of the hallmarks of insect evolution. However, the actual mechanism(s) responsible are yet to be determined. To address this issue, we have now studied the molecular basis of T3 leg enlargement in Oncopeltus fasciatus (milkweed bug) and Acheta domesticus (house cricket). In Oncopeltus, the T3 tibia displays a moderate increase in size, whereas in Acheta, the T3 femur, tibia, and tarsus are all greatly enlarged. Here, we show that the hox gene Ultrabithorax (Ubx) is expressed in the enlarged segments of hind legs. Furthermore, we demonstrate that depletion of Ubx during embryogenesis has a primary effect in T3 legs and causes shortening of leg segments that are enlarged in a wild type. This result shows that Ubx is regulating the differential growth and enlargement of T3 legs in both Oncopeltus and Acheta. The emerging view suggests that Ubx was co-opted for a novel role in regulating leg growth and that the transcriptional modification of its expression may be a universal mechanism for the evolutionary diversification of insect hind legs.
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Affiliation(s)
- Najmus Mahfooz
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Nataliya Turchyn
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Michelle Mihajlovic
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Steven Hrycaj
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Aleksandar Popadić
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
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Mito T, Kobayashi C, Sarashina I, Zhang H, Shinahara W, Miyawaki K, Shinmyo Y, Ohuchi H, Noji S. even-skipped has gap-like, pair-rule-like, and segmental functions in the cricket Gryllus bimaculatus, a basal, intermediate germ insect (Orthoptera). Dev Biol 2007; 303:202-13. [PMID: 17174947 DOI: 10.1016/j.ydbio.2006.11.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 09/13/2006] [Accepted: 11/03/2006] [Indexed: 11/15/2022]
Abstract
Developmental mechanisms of segmentation appear to be varied among insects in spite of their conserved body plan. Although the expression patterns of the segment polarity genes in all insects examined imply well conserved function of this class of genes, expression patterns and function of the pair-rule genes tend to exhibit diversity. To gain further insights into the evolution of the segmentation process and the role of pair-rule genes, we have examined expression and function of an ortholog of the Drosophila pair-rule gene even-skipped (eve) in a phylogenetically basal insect, Gryllus bimaculatus (Orthoptera, intermediate germ cricket). We find that Gryllus eve (Gb'eve) is expressed as stripes in each of the prospective gnathal, thoracic, and abdominal segments and as a broad domain in the posterior growth zone. Dynamics of stripe formation vary among Gb'eve stripes, representing one of the three modes, the segmental, incomplete pair-rule, and complete pair-rule mode. Furthermore, we find that RNAi suppression of Gb'eve results in segmentation defects in both anterior and posterior regions of the embryo. Mild depletion of Gb'eve shows a pair-rule-like defect in anterior segments, while stronger depletion causes a gap-like defect showing deletion of anterior and posterior segments. These results suggest that Gb'eve acts as a pair-rule gene at least during anterior segmentation and also has segmental and gap-like functions. Additionally, Gb'eve may be involved in the regulation of hunchback and Krüppel expression. Comparisons with eve functions in other species suggest that the Gb'eve function may represent an intermediate state of the evolution of pair-rule patterning by eve in insects.
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Affiliation(s)
- Taro Mito
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan
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Nakamura T, Mito T, Tanaka Y, Bando T, Ohuchi H, Noji S. Involvement of canonical Wnt/Wingless signaling in the determination of the positional values within the leg segment of the cricket
Gryllus bimaculatus. Dev Growth Differ 2007; 49:79-88. [PMID: 17335429 DOI: 10.1111/j.1440-169x.2007.00915.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cricket Gryllus bimaculatus is a hemimetabolous insect whose nymphs possess the ability to regenerate amputated legs. Previously, we showed that Gryllus orthologues of Drosophila hedgehog (Gb'hh), wingless (Gb'wg) and decapentaplegic (Gb'dpp) are expressed during leg regeneration and play essential roles in the establishment of the proximal-distal axis. Here, we examined their roles during intercalary regeneration: when a distally amputated tibia with disparate positional values is placed next to a proximally amputated host, intercalary growth occurs in order to regenerate the missing part. In this process, we examined expression patterns of Gb'hh and Gb'wg. We found that expressions of Gb'hh and Gb'wg were induced in a regenerate and the host proximal to the amputated region, but not in the grafted donor distal to the regenerate. This directional induction occurs even in the reversed intercalation. Because these results are consistent with a distal-to-proximal respecification of the regenerate, Gb'wg may be involved in the re-establishment of the positional values in the regenerate. Furthermore, we found that no regeneration occurs when Gb'armadillo (the orthologue of beta-catenin) was knocked down by RNA interference. These results indicate that the canonical Wnt/Wingless signaling pathway is involved in the process of leg regeneration and determination of positional information in the leg segment.
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Affiliation(s)
- Taro Nakamura
- Department of Life System, Institute of Technology and Science, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tolushima City 770-8506, Japan
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Shinmyo Y, Mito T, Uda T, Nakamura T, Miyawaki K, Ohuchi H, Noji S. brachyenteron is necessary for morphogenesis of the posterior gut but not for anteroposterior axial elongation from the posterior growth zone in the intermediate-germband cricket Gryllus bimaculatus. Development 2006; 133:4539-47. [PMID: 17050622 DOI: 10.1242/dev.02646] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the long-germband insect Drosophila, all body segments and posterior terminal structures, including the posterior gut and anal pads, are specified at the blastoderm stage. In short- and intermediate-germband insects, however, posterior segments are sequentially produced from the posterior growth zone, a process resembling somitogenesis in vertebrates, and invagination of the posterior gut starts after anteroposterior (AP) axial elongation from the growth zone. The mechanisms underlying posterior segmentation and terminal patterning in these insects are poorly understood. In order to elucidate these mechanisms, we have investigated the roles of the Brachyury/brachyenteron (Bra/byn) homolog in the intermediate-germband cricket Gryllus bimaculatus. Loss-of-function analysis by RNA interference (RNAi) revealed that Gryllus byn (Gb'byn) is not required for AP axial elongation or normal segment formation, but is required for specification of the posterior gut. We also analyzed Gryllus caudal (Gb'cad) RNAi embryos using in situ hybridization with a Gb'byn probe, and found that Gb'cad is required for internalization of the posterior gut primordium, in addition to AP axial elongation. These results suggest that the functions of byn and cad in posterior terminal patterning are highly conserved in Gryllus and Drosophila despite their divergent posterior patterning. Moreover, because it is thought that the progressive growth of the AP axis from the growth zone, controlled by a genetic program involving Cdx/cad and Bra/byn, might be ancestral to bilaterians, our data suggest that the function of Bra/byn in this process might have been lost in insects.
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Affiliation(s)
- Yohei Shinmyo
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minami-Josanjima-cho, Tokushima City 770-8506, Japan
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Blagburn JM. Co-factors and co-repressors of Engrailed: expression in the central nervous system and cerci of the cockroach, Periplaneta americana. Cell Tissue Res 2006; 327:177-87. [PMID: 17024417 DOI: 10.1007/s00441-006-0300-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 07/10/2006] [Indexed: 10/24/2022]
Abstract
In the larval cockroach (Periplaneta americana), knockout of Engrailed (En) in the medial sensory neurons of the cercal sensory system changes their axonal arborization and synaptic specificity. Immunocytochemistry has been used to investigate whether the co-repressor Groucho (Gro; vertebrate homolog: TLE) and the co-factor Extradenticle (Exd; vertebrate homolog: Pbx) are expressed in the cercal system. Gro/TLE is expressed ubiquitously in cell nuclei in the embryo, except for the distal pleuropodia. Gro is expressed in all nuclei of the thoracic and abdominal central nervous system (CNS) of first instar larva, although some neurons express less Gro than others. Cercal sensory neurons express Gro protein, which might therefore act as a co-repressor with En. Exd/Pbx is expressed in the proximal portion of all segmental appendages in the embryo, with the exception of the cerci. In the first instar CNS, Exd protein is expressed in subsets of neurons (including dorsal unpaired medial neurons) in the thoracic ganglia, in the first two abdominal ganglia, and in neuromeres A8-A11 of the terminal ganglion. Exd is absent from the cerci. Because Ultrabithorax/Abdominal-A (Ubx/Abd-A) can substitute for Exd as En co-factors in Drosophila, Ubx/Abd-A immunoreactivity has also been investigated. Ubx/Abd-A immunostaining is present in abdominal segments of the embryo and first instar CNS as far caudal as A7 and faintly in the T3 segment. However, Ubx/Abd-A is absent in the cerci and their neurons. Thus, in contrast to its role in Drosophila segmentation, En does not require the co-factors Exd or Ubx/Abd-A in order to control the synaptic specificity of cockroach sensory neurons.
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Affiliation(s)
- Jonathan M Blagburn
- Institute of Neurobiology and Department of Physiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico.
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Mito T, Okamoto H, Shinahara W, Shinmyo Y, Miyawaki K, Ohuchi H, Noji S. Krüppel acts as a gap gene regulating expression of hunchback and even-skipped in the intermediate germ cricket Gryllus bimaculatus. Dev Biol 2006; 294:471-81. [PMID: 16616119 DOI: 10.1016/j.ydbio.2005.12.057] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 12/22/2005] [Accepted: 12/27/2005] [Indexed: 11/19/2022]
Abstract
In Drosophila, a long germ insect, segmentation occurs simultaneously across the entire body. In contrast, in short and intermediate germ insects, the anterior segments are specified during the blastoderm stage, while the remaining posterior segments are specified during later stages. In Drosophila embryos, the transcriptional factors coded by gap genes, such as Krüppel, diffuse in the syncytial environment and regulate the expression of other gap, pair-rule, and Hox genes. To understand the segmentation mechanisms in short and intermediate germ insects, we investigated the role of Kr ortholog (Gb'Kr) in the development of the intermediate germ insect Gryllus bimaculatus. We found that Gb'Kr is expressed in a gap pattern in the prospective thoracic region after cellularization of the embryo. To determine the function of Gb'Kr in segmentation, we analyzed knockdown phenotypes using RNA interference (RNAi). Gb'Kr RNAi depletion resulted in a gap phenotype in which the posterior of the first thoracic through seventh abdominal segments were deleted. Analysis of the expression patterns of Hox genes in Gb'Kr RNAi embryos indicated that regulatory relationships between Hox genes and Kr in Gryllus differ from those in Oncopeltus, another intermediate germ insect. Furthermore, we found that Gb'Kr regulates expression minimally of hunchback and even-skipped, directly or indirectly, in the prospective thoracic region. Our findings suggest that Gb'Kr is a gap gene that acts in the cellular environment and is required for segmentation in the thoracic and abdominal regions through the regulation of gap and pair-rule gene expression.
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Affiliation(s)
- Taro Mito
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan
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Mito T, Sarashina I, Zhang H, Iwahashi A, Okamoto H, Miyawaki K, Shinmyo Y, Ohuchi H, Noji S. Non-canonical functions of hunchback in segment patterning of the intermediate germ cricket Gryllus bimaculatus. Development 2005; 132:2069-79. [PMID: 15788457 DOI: 10.1242/dev.01784] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In short and intermediate germ insects, only the anterior segments are specified during the blastoderm stage, leaving the posterior segments to be specified later, during embryogenesis, which differs from the segmentation process in Drosophila, a long germ insect. To elucidate the segmentation mechanisms of short and intermediate germ insects, we have investigated the orthologs of the Drosophila segmentation genes in a phylogenetically basal, intermediate germ insect, Gryllus bimaculatus(Gb). Here, we have focused on its hunchback ortholog(Gb'hb), because Drosophila hb functions as a gap gene during anterior segmentation, referred as a canonical function. Gb'hb is expressed in a gap pattern during the early stages of embryogenesis, and later in the posterior growth zone. By means of embryonic and parental RNA interference for Gb'hb, we found the following: (1) Gb'hb regulates Hox gene expression to specify regional identity in the anterior region, as observed in Drosophila and Oncopeltus; (2) Gb'hb controls germband morphogenesis and segmentation of the anterior region, probably through the pair-rule gene, even-skipped at least; (3) Gb'hb may act as a gap gene in a limited region between the posterior of the prothoracic segment and the anterior of the mesothoracic segment; and (4) Gb'hb is involved in the formation of at least seven abdominal segments, probably through its expression in the posterior growth zone, which is not conserved in Drosophila. These findings suggest that Gb'hb functions in a non-canonical manner in segment patterning. A comparison of our results with the results for other derived species revealed that the canonical hbfunction may have evolved from the non-canonical hb functions during evolution.
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Affiliation(s)
- Taro Mito
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan
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