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Liu BP, Hua BZ. Distinct roles of the Hox genes Ultrabithorax and abdominal-A in scorpionfly embryonic proleg development. INSECT MOLECULAR BIOLOGY 2024; 33:69-80. [PMID: 37792400 DOI: 10.1111/imb.12878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 09/21/2023] [Indexed: 10/05/2023]
Abstract
The abdominal appendages of larval insects have a complex evolutionary history of gain and loss, but the regulatory mechanisms underlying the abdominal appendage development remain largely unclear. Here, we investigated the embryogenesis of abdominal prolegs in the scorpionfly Panorpa liui Hua (Mecoptera: Panorpidae) using in situ hybridization and parental RNA interference. The results show that RNAi-mediated knockdown of Ultrabithorax (Ubx) led to a homeotic transformation of the first abdominal segment (A1) into the third thoracic segment (T3) and changed the distributions of the downstream target Distal-less (Dll) expression but did not affect the expression levels of Dll. Knockdown of abdominal-A (abd-A) resulted in malformed segments, abnormal prolegs and disrupted Dll expression. The results demonstrate that the gene Ubx maintains an ancestral role of modulating A1 appendage fate without preventing Dll initiation, and a secondary adaptation of abd-A evolves the ability to specify abdominal segments and proleg identity. We conclude that changes in abdominal Hox gene expression and their target genes regulate abdominal appendage morphology during the evolutionary course of holometabolous larvae.
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Affiliation(s)
- Bing-Peng Liu
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Bao-Zhen Hua
- Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, China
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2
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Tendolkar A, Mazo-Vargas A, Livraghi L, Hanly JJ, Van Horne KC, Gilbert LE, Martin A. Cis-regulatory modes of Ultrabithorax inactivation in butterfly forewings. eLife 2024; 12:RP90846. [PMID: 38261357 PMCID: PMC10945631 DOI: 10.7554/elife.90846] [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] [Indexed: 01/24/2024] Open
Abstract
Hox gene clusters encode transcription factors that drive regional specialization during animal development: for example the Hox factor Ubx is expressed in the insect metathoracic (T3) wing appendages and differentiates them from T2 mesothoracic identities. Hox transcriptional regulation requires silencing activities that prevent spurious activation and regulatory crosstalks in the wrong tissues, but this has seldom been studied in insects other than Drosophila, which shows a derived Hox dislocation into two genomic clusters that disjoined Antennapedia (Antp) and Ultrabithorax (Ubx). Here, we investigated how Ubx is restricted to the hindwing in butterflies, amidst a contiguous Hox cluster. By analysing Hi-C and ATAC-seq data in the butterfly Junonia coenia, we show that a Topologically Associated Domain (TAD) maintains a hindwing-enriched profile of chromatin opening around Ubx. This TAD is bordered by a Boundary Element (BE) that separates it from a region of joined wing activity around the Antp locus. CRISPR mutational perturbation of this BE releases ectopic Ubx expression in forewings, inducing homeotic clones with hindwing identities. Further mutational interrogation of two non-coding RNA encoding regions and one putative cis-regulatory module within the Ubx TAD cause rare homeotic transformations in both directions, indicating the presence of both activating and repressing chromatin features. We also describe a series of spontaneous forewing homeotic phenotypes obtained in Heliconius butterflies, and discuss their possible mutational basis. By leveraging the extensive wing specialization found in butterflies, our initial exploration of Ubx regulation demonstrates the existence of silencing and insulating sequences that prevent its spurious expression in forewings.
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Affiliation(s)
- Amruta Tendolkar
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
| | - Anyi Mazo-Vargas
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
| | - Luca Livraghi
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
| | - Joseph J Hanly
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
- Smithsonian Tropical Research InstitutePanama CityPanama
| | - Kelsey C Van Horne
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
| | - Lawrence E Gilbert
- Department of Integrative Biology, University of Texas – AustinAustinUnited States
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington UniversityWashington, DCUnited States
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Janssen R, Pechmann M. Expression of posterior Hox genes and opisthosomal appendage development in a mygalomorph spider. Dev Genes Evol 2023; 233:107-121. [PMID: 37495828 PMCID: PMC10746769 DOI: 10.1007/s00427-023-00707-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 07/11/2023] [Indexed: 07/28/2023]
Abstract
Spiders represent an evolutionary successful group of chelicerate arthropods. The body of spiders is subdivided into two regions (tagmata). The anterior tagma, the prosoma, bears the head appendages and four pairs of walking legs. The segments of the posterior tagma, the opisthosoma, either lost their appendages during the course of evolution or their appendages were substantially modified to fulfill new tasks such as reproduction, gas exchange, and silk production. Previous work has shown that the homeotic Hox genes are involved in shaping the posterior appendages of spiders. In this paper, we investigate the expression of the posterior Hox genes in a tarantula that possesses some key differences of posterior appendages compared to true spiders, such as the lack of the anterior pair of spinnerets and a second set of book lungs instead of trachea. Based on the observed differences in posterior Hox gene expression in true spiders and tarantulas, we argue that subtle changes in the Hox gene expression of the Hox genes abdA and AbdB are possibly responsible for at least some of the morphological differences seen in true spiders versus tarantulas.
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Affiliation(s)
- Ralf Janssen
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, 75236, Uppsala, Sweden.
| | - Matthias Pechmann
- Institute for Zoology, Biocenter, University of Cologne, Zuelpicher Str. 47b, 50674, Cologne, Germany
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Ador K, Gobilik J, Benedick S. Phylogenetic and Morphological Characteristics Reveal Cryptic Speciation in Stingless Bee, Tetragonula laeviceps s.l. Smith 1857 (Hymenoptera; Meliponinae). INSECTS 2023; 14:insects14050438. [PMID: 37233066 DOI: 10.3390/insects14050438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 05/27/2023]
Abstract
Tetragonula laeviceps sensu lato (s.l.) Smith 1857 has the most complicated nomenclatural history among the Tetragonula genera. The objective of this study was to investigate whether T. laeviceps s.l. individuals with worker bees are grouped in the same or nearly the same morphological characteristics and have similar COI haplotype cluster groups. A total of 147 worker bees of T. laeviceps s.l. were collected from six sampling sites in Sabah (RDC, Tuaran, Kota Marudu, Putatan, Kinarut and Faculty of Sustainable Agriculture (FSA)), but only 36 were selected for further studies. These specimens were first classified according to the most obvious morphological characteristics, i.e., hind tibia color, hind basitarsus color and body size. Group identification was based on morphological characteristics important for distinguishing the four groups within T. laeviceps s.l. The four groups of T. laeviceps s.l. had significantly different body trait measurements for the TL (total length), HW (head width), HL (head length), CEL (compound eye length), CEW (compound eye width), FWLT (forewing length, including tegula), FWW (forewing width), FWL (forewing length), ML (mesoscutum length), MW (mesoscutum width), SW (mesoscutellum width), SL (mesoscutellum length), HTL = (hind tibia length), HTW (hind tibia width), HBL (hind basitarsus length) and HBW (hind basitarsus width) (p < 0.001). Body color included HC (head color), CC (clypeus color), ASC (antennae scape color), CFPP (Clypeus and frons plumose pubescence), HTC (hind tibia color), BSC (basitarsus color), SP (leg setae pubescence), SP (Thorax mesoscutellum pubescence), SPL (thorax mesoscutellum pubescence length) and TC (thorax color) (p < 0.05). The most distinctive features of the morphological and morphometric characteristics measured by PCA and LDA biplot that distinguish Group 1 (TL6-1, TL6-2 and TL6-3) from the other groups were the yellowish-brown ASC and the dark brown TC. Group 2 (haplotypes TL2-1, TL2-2 and TL2-3 and TL4-1, TL4-2 and TL4-3) had a dark brown ASC and a black TC, while Group 3 (haplotypes TL11-1, TL11-2 and TL11-3) had a blackish-brown ASC, a black TC and the largest TL, FWW and FWL. As for phylogenetic relationships, 12 out of 36 haplotypes showed clear separation with good bootstrap values (97-100%). The rest of the haplotypes did not show clear differentiation between subclades that belonged together, regardless of their morphology and morphometric characteristics. This suggests that the combination of DNA barcoding for species identification and phylogenetic analysis, as well as traditional methods based on morphological grouping by body size and body color, can be reliably used to determine intraspecific variations within T. laeviceps s.l.
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Affiliation(s)
- Kimberly Ador
- Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Locked Bag No. 3, Sandakan 90509, Malaysia
| | - Januarius Gobilik
- Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Locked Bag No. 3, Sandakan 90509, Malaysia
| | - Suzan Benedick
- Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Locked Bag No. 3, Sandakan 90509, Malaysia
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Gainett G, Klementz BC, Blaszczyk PO, Bruce HS, Patel NH, Sharma PP. Dual Functions of labial Resolve the Hox Logic of Chelicerate Head Segments. Mol Biol Evol 2023; 40:7043718. [PMID: 36798978 PMCID: PMC10015621 DOI: 10.1093/molbev/msad037] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/10/2023] [Accepted: 02/10/2023] [Indexed: 02/18/2023] Open
Abstract
Despite an abundance of gene expression surveys, comparatively little is known about Hox gene function in Chelicerata. Previous investigations of paralogs of labial (lab) and Deformed (Dfd) in a spider have shown that these play a role in tissue maintenance of the pedipalp segment (lab-1) and in patterning the first walking leg identity (Dfd-1), respectively. However, extrapolations of these data across chelicerates are hindered by the existence of duplicated Hox genes in arachnopulmonates (e.g., spiders and scorpions), which have resulted from an ancient whole genome duplication (WGD) event. Here, we investigated the function of the single-copy ortholog of lab in the harvestman Phalangium opilio, an exemplar of a lineage that was not subject to this WGD. Embryonic RNA interference against lab resulted in two classes of phenotypes: homeotic transformations of pedipalps to chelicerae, as well as reduction and fusion of the pedipalp and leg 1 segments. To test for combinatorial function, we performed a double knockdown of lab and Dfd, which resulted in a homeotic transformation of both pedipalps and the first walking legs into cheliceral identity, whereas the second walking leg is transformed into a pedipalpal identity. Taken together, these results elucidate a model for the Hox logic of head segments in Chelicerata. To substantiate the validity of this model, we performed expression surveys for lab and Dfd paralogs in scorpions and horseshoe crabs. We show that repetition of morphologically similar appendages is correlated with uniform expression levels of the Hox genes lab and Dfd, irrespective of the number of gene copies.
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Affiliation(s)
- Guilherme Gainett
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI
| | - Benjamin C Klementz
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI
| | - Pola O Blaszczyk
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI
| | | | - Nipam H Patel
- Marine Biological Laboratory, Woods Hole, MA.,Organismal Biology & Anatomy, University of Chicago, Chicago, IL
| | - Prashant P Sharma
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI
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Matsuoka Y, Monteiro A. Ultrabithorax modifies a regulatory network of genes essential for butterfly eyespot development in a wing sector-specific manner. Development 2022; 149:285574. [PMID: 36341494 DOI: 10.1242/dev.200781] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022]
Abstract
Nymphalid butterfly species often have a different number of eyespots in forewings and hindwings, but how the hindwing identity gene Ultrabithorax (Ubx) drives this asymmetry is not fully understood. We examined a three-gene regulatory network for eyespot development in the hindwings of Bicyclus anynana butterflies and compared it with the same network previously described for forewings. We also examined how Ubx interacts with each of these three eyespot-essential genes. We found similar genetic interactions between the three genes in fore- and hindwings, but we discovered three regulatory differences: Antennapedia (Antp) merely enhances spalt (sal) expression in the eyespot foci in hindwings, but is not essential for sal activation, as in forewings; Ubx upregulates Antp in all hindwing eyespot foci but represses Antp outside these wing regions; and Ubx regulates sal in a wing sector-specific manner, i.e. it activates sal expression only in the sectors that have hindwing-specific eyespots. We propose a model for how the regulatory connections between these four genes evolved to produce wing- and sector-specific variation in eyespot number.
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Affiliation(s)
- Yuji Matsuoka
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Block S2, Level 1, 117543Singapore
| | - Antónia Monteiro
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Block S2, Level 1, 117543Singapore
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Elias-Neto M, Alvarez N, Ventos-Alfonso A, Belles X. Flight or protection: the genes Ultrabithorax and apterous in the determination of membranous and sclerotized wings in insects. Proc Biol Sci 2022; 289:20220967. [PMID: 35975435 PMCID: PMC9382207 DOI: 10.1098/rspb.2022.0967] [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] [Indexed: 12/14/2022] Open
Abstract
Present-day pterygote insects have two pairs of wings, one in the mesothorax (T2), the other in the metathorax (T3), and both have diverged in structure and function in different groups. Studies in endopterygote and paraneopteran species have shown that the gene Ultrabithorax (Ubx) specifies the identity and wing structure in T3, whereas the gene apterous (ap) significantly contributes to forming modified T2 wings. We wondered whether these Ubx and ap mechanisms operate in the lineage of polyneopterans. To explore this possibility, we used the cockroach Blattella germanica (Polyneoptera and Blattodea), in which the T2 wings are sclerotized (tegmina), whereas those of the T3 are membranous. We found that Ubx determines the structure of T3 and the membranous wing, while ap significantly contributes to form the sclerotized T2 tegmina. These results along with the studies carried out on the beetle Tribolium castaneum by Tomoyasu and collaborators suggest that ap plays an important role in the sclerotization and melanization of the T2 wings in neopteran groups that have sclerotized forewings. In turn, the sclerotizing properties of ap demonstrated in beetles and cockroaches suggest that the origin of this function goes back to the emergence of Neoptera, in the mid Devonian.
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Affiliation(s)
- Moysés Elias-Neto
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
| | - Niuska Alvarez
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
| | - Alba Ventos-Alfonso
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
| | - Xavier Belles
- Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, Barcelona, Spain
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8
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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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Armisén D, Khila A. Genomics of the semi-aquatic bugs (Heteroptera; Gerromorpha): recent advances toward establishing a model lineage for the study of phenotypic evolution. CURRENT OPINION IN INSECT SCIENCE 2022; 50:100870. [PMID: 34990871 DOI: 10.1016/j.cois.2021.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 12/08/2021] [Accepted: 12/29/2021] [Indexed: 06/14/2023]
Abstract
Gerromorpha, also known as semi-aquatic bugs, present the striking capability to walk on water surface, which has long attracted the interest of many scientists. Yet our understanding of the mechanisms associated with their adaptation and diversification within this new habitat remain largely unknown. In this review we discuss how new transcriptomic and genomic resources have contributed to establish the Gerromorpha as an important lineage to study phenotypic evolution. In particular we outline the impact of recent comparative transcriptomic analyses and first published genomes to advance our understanding of genomic basis of adaptations to water surface locomotion and sexual dimorphism.
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Affiliation(s)
- David Armisén
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 Lyon Cedex 07, France.
| | - Abderrahman Khila
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 Lyon Cedex 07, France
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10
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Markevich D, Walczak M, Borodin O, Szwedo J, Brożek J. Morphological reassessment of the movable calcar of delphacid planthoppers (Hemiptera: Fulgoromorpha: Delphacidae). Sci Rep 2021; 11:22294. [PMID: 34785713 PMCID: PMC8595309 DOI: 10.1038/s41598-021-01771-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 11/01/2021] [Indexed: 11/08/2022] Open
Abstract
This study presents the morphology of calcar in adult Delphacidae based on representatives of the genera Ugyops Guérin-Meneville, 1834, Notuchus Fennah, 1969 (Ugyopini), Asiraca Latreille, 1798 (Asiracini), Kelisia Fieber, 1866, (Kelisini), Stenocranus Fieber, 1866 (Stenocranini), Chloriona Fieber, 1866, Megadelphax Wagner, 1963, Muellerianella Wagner, 1963, Javesella Fennah, 1963, Conomelus Fieber, 1866, Euconomelus Haupt, 1929, Hyledelphax Vilbaste, 1968, Stiroma Fieber, 1866, Struebingianella Wagner, 1963 and Xanthodelphax Wagner, 1963 (Delphacini). We used SEM electron microscopy, to define seven types of calcar structure (Types 1, 2, 5, 6, 7, 8, and 9) based on combinations of characters including shape, number of teeth and differentiation of sensory structures in species from fifteen genera. Additionally, two other types (Types 3 and 4) were determined based on the calcar descriptions from previous studies. Similarities and differences in calcar structure and function were discussed and emerging relationships between planthopper species and their particular habitats were indicated.
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Affiliation(s)
- Darya Markevich
- State Scientific and Production Amalgamation The Scientific and Practical Center for Bioresources, Laboratory of Terrestrial Invertebrates, National Academy of Sciences of Belarus, 27, Akademicheskaya Str., 220050, Minsk, Belarus
| | - Marcin Walczak
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 9, Bankowa St., 40007, Katowice, Poland
| | - Oleg Borodin
- Institute of Systematic Biology, Daugavpils University, 13 - 229 Vienības Street, Daugavpils, 5401, Latvia
| | - Jacek Szwedo
- Laboratory of Evolutionary Entomology and Museum of Amber Inclusions, Department of Invertebrate Zoology and Parasitology, Faculty of Biology, University of Gdańsk, 59, Wita Stwosza St., 80309, Gdańsk, Poland.
| | - Jolanta Brożek
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 9, Bankowa St., 40007, Katowice, Poland.
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Tendolkar A, Pomerantz AF, Heryanto C, Shirk PD, Patel NH, Martin A. Ultrabithorax Is a Micromanager of Hindwing Identity in Butterflies and Moths. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.643661] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The forewings and hindwings of butterflies and moths (Lepidoptera) are differentiated from each other, with segment-specific morphologies and color patterns that mediate a wide range of functions in flight, signaling, and protection. The Hox geneUltrabithorax(Ubx) is a master selector gene that differentiates metathoracic from mesothoracic identities across winged insects, and previous work has shown this role extends to at least some of the color patterns from the butterfly hindwing. Here we used CRISPR targeted mutagenesis to generateUbxloss-of-function somatic mutations in two nymphalid butterflies (Junonia coenia,Vanessa cardui) and a pyralid moth (Plodia interpunctella). The resulting mosaic clones yielded hindwing-to-forewing transformations, showingUbxis necessary for specifying many aspects of hindwing-specific identities, including scale morphologies, color patterns, and wing venation and structure. These homeotic phenotypes showed cell-autonomous, sharp transitions between mutant and non-mutant scales, except for clones that encroached into the border ocelli (eyespots) and resulted in composite and non-autonomous effects on eyespot ring determination. In the pyralid moth, homeotic clones converted the folding and depigmented hindwing into rigid and pigmented composites, affected the wing-coupling frenulum, and induced ectopic scent-scales in male androconia. These data confirmUbxis a master selector of lepidopteran hindwing identity and suggest it acts on many gene regulatory networks involved in wing development and patterning.
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12
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Location and arrangement of campaniform sensilla in
Drosophila melanogaster. J Comp Neurol 2020; 529:905-925. [DOI: 10.1002/cne.24987] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/19/2020] [Accepted: 07/01/2020] [Indexed: 11/07/2022]
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13
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Fu SJ, Zhang JL, Chen SJ, Chen HH, Liu YL, Xu HJ. Functional analysis of Ultrabithorax in the wing-dimorphic planthopper Nilaparvata lugens (Stål, 1854) (Hemiptera: Delphacidae). Gene 2020; 737:144446. [DOI: 10.1016/j.gene.2020.144446] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 01/24/2023]
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A hemipteran insect reveals new genetic mechanisms and evolutionary insights into tracheal system development. Proc Natl Acad Sci U S A 2020; 117:4252-4261. [PMID: 32041884 DOI: 10.1073/pnas.1908975117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The diversity in the organization of the tracheal system is one of the drivers of insect evolutionary success; however, the genetic mechanisms responsible are yet to be elucidated. Here, we highlight the advantages of utilizing hemimetabolous insects, such as the milkweed bug Oncopeltus fasciatus, in which the final adult tracheal patterning can be directly inferred by examining its blueprint in embryos. By reporting the expression patterns, functions, and Hox gene regulation of trachealess (trh), ventral veinless (vvl), and cut (ct), key genes involved in tracheal development, this study provides important insights. First, Hox genes function as activators, modifiers, and suppressors of trh expression, which in turn results in a difference between the thoracic and abdominal tracheal organization. Second, spiracle morphogenesis requires the input of both trh and ct, where ct is positively regulated by trh As Hox genes regulate trh, we can now mechanistically explain the previous observations of their effects on spiracle formation. Third, the default state of vvl expression in the thorax, in the absence of Hox gene expression, features three lateral cell clusters connected to ducts. Fourth, the exocrine scent glands express vvl and are regulated by Hox genes. These results extend previous findings [Sánchez-Higueras et al., 2014], suggesting that the exocrine glands, similar to the endocrine, develop from the same primordia that give rise to the trachea. The presence of such versatile primordia in the miracrustacean ancestor could account for the similar gene networks found in the glandular and respiratory organs of both insects and crustaceans.
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Tian L, Rahman SR, Ezray BD, Franzini L, Strange JP, Lhomme P, Hines HM. A homeotic shift late in development drives mimetic color variation in a bumble bee. Proc Natl Acad Sci U S A 2019; 116:11857-11865. [PMID: 31043564 PMCID: PMC6575597 DOI: 10.1073/pnas.1900365116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Natural phenotypic radiations, with their high diversity and convergence, are well-suited for informing how genomic changes translate to natural phenotypic variation. New genomic tools enable discovery in such traditionally nonmodel systems. Here, we characterize the genomic basis of color pattern variation in bumble bees (Hymenoptera, Apidae, Bombus), a group that has undergone extensive convergence of setal color patterns as a result of Müllerian mimicry. In western North America, multiple species converge on local mimicry patterns through parallel shifts of midabdominal segments from red to black. Using genome-wide association, we establish that a cis-regulatory locus between the abdominal fate-determining Hox genes, abd-A and Abd-B, controls the red-black color switch in a western species, Bombus melanopygus Gene expression analysis reveals distinct shifts in Abd-B aligned with the duration of setal pigmentation at the pupal-adult transition. This results in atypical anterior Abd-B expression, a late developmental homeotic shift. Changing expression of Hox genes can have widespread effects, given their important role across segmental phenotypes; however, the late timing reduces this pleiotropy, making Hox genes suitable targets. Analysis of this locus across mimics and relatives reveals that other species follow independent genetic routes to obtain the same phenotypes.
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Affiliation(s)
- Li Tian
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | | | - Briana D Ezray
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802
| | - Luca Franzini
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802
| | - James P Strange
- United States Department of Agriculture-Agricultural Research Service Pollinating Insects Research Unit, Utah State University, Logan, UT 84322
| | - Patrick Lhomme
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
- Biodiversity and Crop Improvement Program, International Center of Agricultural Research in the Dry Areas, 10112 Rabat, Morocco
| | - Heather M Hines
- Department of Biology, The Pennsylvania State University, University Park, PA 16802;
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802
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16
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Sanger TJ, Rajakumar R. How a growing organismal perspective is adding new depth to integrative studies of morphological evolution. Biol Rev Camb Philos Soc 2019; 94:184-198. [PMID: 30009397 DOI: 10.1111/brv.12442] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 06/11/2018] [Accepted: 06/14/2018] [Indexed: 01/24/2023]
Abstract
Over the past half century, the field of Evolutionary Developmental Biology, or Evo-devo, has integrated diverse fields of biology into a more synthetic understanding of morphological diversity. This has resulted in numerous insights into how development can evolve and reciprocally influence morphological evolution, as well as generated several novel theoretical areas. Although comparative by default, there remains a great gap in our understanding of adaptive morphological diversification and how developmental mechanisms influence the shape and pattern of phenotypic variation. Herein we highlight areas of research that are in the process of filling this void, and areas, if investigated more fully, that will add new insights into the diversification of morphology. At the centre of our discussion is an explicit awareness of organismal biology. Here we discuss an organismal framework that is supported by three distinct pillars. First, there is a need for Evo-devo to adopt a high-resolution phylogenetic approach in the study of morphological variation and its developmental underpinnings. Secondly, we propose that to understand the dynamic nature of morphological evolution, investigators need to give more explicit attention to the processes that generate evolutionarily relevant variation at the population level. Finally, we emphasize the need to address more thoroughly the processes that structure variation at micro- and macroevolutionary scales including modularity, morphological integration, constraint, and plasticity. We illustrate the power of these three pillars using numerous examples from both invertebrates and vertebrates to emphasize that many of these approaches are already present within the field, but have yet to be formally integrated into many research programs. We feel that the most exciting new insights will come where the traditional experimental approaches to Evo-devo are integrated more thoroughly with the principles of this organismal framework.
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Affiliation(s)
- Thomas J Sanger
- Department of Biology, Loyola University Chicago, Chicago, IL 60660, U.S.A
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17
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Eksi SE, Barmina O, McCallough CL, Kopp A, Orenic TV. A Distalless-responsive enhancer of the Hox gene Sex combs reduced is required for segment- and sex-specific sensory organ development in Drosophila. PLoS Genet 2018; 14:e1007320. [PMID: 29634724 PMCID: PMC5909922 DOI: 10.1371/journal.pgen.1007320] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/20/2018] [Accepted: 03/19/2018] [Indexed: 11/18/2022] Open
Abstract
Hox genes are involved in the patterning of animal body parts at multiple levels of regulatory hierarchies. Early expression of Hox genes in different domains along the embryonic anterior-posterior (A/P) axis in insects, vertebrates, and other animals establishes segmental or regional identity. However, Hox gene function is also required later in development for the patterning and morphogenesis of limbs and other organs. In Drosophila, spatiotemporal modulation of Sex combs reduced (Scr) expression within the first thoracic (T1) leg underlies the generation of segment- and sex-specific sense organ patterns. High Scr expression in defined domains of the T1 leg is required for the development of T1-specific transverse bristle rows in both sexes and sex combs in males, implying that the patterning of segment-specific sense organs involves incorporation of Scr into the leg development and sex determination gene networks. We sought to gain insight into this process by identifying the cis-and trans-regulatory factors that direct Scr expression during leg development. We have identified two cis-regulatory elements that control spatially modulated Scr expression within T1 legs. One of these enhancers directs sexually dimorphic expression and is required for the formation of T1-specific bristle patterns. We show that the Distalless and Engrailed homeodomain transcription factors act through sequences in this enhancer to establish elevated Scr expression in spatially defined domains. This enhancer functions to integrate Scr into the intrasegmental gene regulatory network, such that Scr serves as a link between leg patterning, sex determination, and sensory organ development.
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Affiliation(s)
- Sebnem Ece Eksi
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Olga Barmina
- Department of Evolution and Ecology, University of California-Davis, Davis, CA, United States of America
| | - Christopher L. McCallough
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Artyom Kopp
- Department of Evolution and Ecology, University of California-Davis, Davis, CA, United States of America
- * E-mail: (AK); (TVO)
| | - Teresa Vales Orenic
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States of America
- * E-mail: (AK); (TVO)
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18
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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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Abstract
Hox proteins are a deeply conserved group of transcription factors originally defined for their critical roles in governing segmental identity along the antero-posterior (AP) axis in
Drosophila. Over the last 30 years, numerous data generated in evolutionarily diverse taxa have clearly shown that changes in the expression patterns of these genes are closely associated with the regionalization of the AP axis, suggesting that
Hox genes have played a critical role in the evolution of novel body plans within Bilateria. Despite this deep functional conservation and the importance of these genes in AP patterning, key questions remain regarding many aspects of
Hox biology. In this commentary, we highlight recent reports that have provided novel insight into the origins of the mammalian
Hox cluster, the role of
Hox genes in the generation of a limbless body plan, and a novel putative mechanism in which
Hox genes may encode specificity along the AP axis. Although the data discussed here offer a fresh perspective, it is clear that there is still much to learn about
Hox biology and the roles it has played in the evolution of the Bilaterian body plan.
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Affiliation(s)
- Steven M Hrycaj
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, 48109-2200, USA
| | - Deneen M Wellik
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, 48109-2200, USA; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, 48109-2200, USA
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Abstract
Winged insects underwent an unparalleled evolutionary radiation, but mechanisms underlying the origin and diversification of wings in basal insects are sparsely known compared with more derived holometabolous insects. In the neopteran species Oncopeltus fasciatus, we manipulated wing specification genes and used RNA-seq to obtain both functional and genomic perspectives. Combined with previous studies, our results suggest the following key steps in wing origin and diversification. First, a set of dorsally derived outgrowths evolved along a number of body segments including the first thoracic segment (T1). Homeotic genes were subsequently co-opted to suppress growth of some dorsal flaps in the thorax and abdomen. In T1 this suppression was accomplished by Sex combs reduced, that when experimentally removed, results in an ectopic T1 flap similar to prothoracic winglets present in fossil hemipteroids and other early insects. Global gene-expression differences in ectopic T1 vs. T2/T3 wings suggest that the transition from flaps to wings required ventrally originating cells, homologous with those in ancestral arthropod gill flaps/epipods, to migrate dorsally and fuse with the dorsal flap tissue thereby bringing new functional gene networks; these presumably enabled the T2/T3 wing's increased size and functionality. Third, "fused" wings became both the wing blade and surrounding regions of the dorsal thorax cuticle, providing tissue for subsequent modifications including wing folding and the fit of folded wings. Finally, Ultrabithorax was co-opted to uncouple the morphology of T2 and T3 wings and to act as a general modifier of hindwings, which in turn governed the subsequent diversification of lineage-specific wing forms.
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Gotoh H, Hust JA, Miura T, Niimi T, Emlen DJ, Lavine LC. The Fat/Hippo signaling pathway links within-disc morphogen patterning to whole-animal signals during phenotypically plastic growth in insects. Dev Dyn 2015; 244:1039-1045. [DOI: 10.1002/dvdy.24296] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 12/11/2022] Open
Affiliation(s)
- Hiroki Gotoh
- Graduate School of Bioagricultural Sciences, Nagoya University; Chikusa Nagoya Japan
| | - James A. Hust
- Department of Entomology; Washington State University; Pullman Washington
| | - Toru Miura
- Graduate School of Environmental Science, Hokkaido University; Sapporo Hokkaido Japan
| | - Teruyuki Niimi
- Graduate School of Bioagricultural Sciences, Nagoya University; Chikusa Nagoya Japan
| | - Douglas J. Emlen
- Division of Biological Sciences; University of Montana-Missoula; Montana
| | - Laura C. Lavine
- Department of Entomology; Washington State University; Pullman Washington
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22
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Refki PN, Armisén D, Crumière AJJ, Viala S, Khila A. Emergence of tissue sensitivity to Hox protein levels underlies the evolution of an adaptive morphological trait. Dev Biol 2014; 392:441-53. [PMID: 24886828 PMCID: PMC4111901 DOI: 10.1016/j.ydbio.2014.05.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 05/20/2014] [Accepted: 05/24/2014] [Indexed: 11/16/2022]
Abstract
Growth control scales morphological attributes and, therefore, provides a critical contribution to the evolution of adaptive traits. Yet, the genetic mechanisms underlying growth in the context of specific ecological adaptations are poorly understood. In water striders, adaptation to locomotion on the water surface is associated with allometric and functional changes in thoracic appendages, such that T2-legs, used as propelling oars, are longer than T3-legs, used as steering rudders. The Hox gene Ubx establishes this derived morphology by elongating T2-legs but shortening T3-legs. Using gene expression assays, RNAi knockdown, and comparative transcriptomics, we demonstrate that the evolution of water surface rowing as a novel means of locomotion is associated with the evolution of a dose-dependent promoting-repressing effect of Ubx on leg growth. In the water strider Limnoporus dissortis, T3-legs express six to seven times higher levels of Ubx compared to T2-legs. Ubx RNAi shortens T2-legs and the severity of this phenotype increases with increased depletion of Ubx protein. Conversely, Ubx RNAi lengthens T3-legs but this phenotype is partially rescued when Ubx protein is further depleted. This dose-dependent effect of Ubx on leg growth is absent in non-rowing relatives that retain the ancestral relative leg length. We also show that the spatial patterns of expression of dpp, wg, hh, egfr, dll, exd, hth, and dac are unchanged in Ubx RNAi treatments. This indicates that the dose-dependent opposite effect of Ubx on T2- and T3-legs operates without any apparent effect on the spatial expression of major leg patterning genes. Our data suggest that scaling of adaptive allometries can evolve through changes in the levels of expression of Hox proteins early during ontogeny, and in the sensitivity of the tissues that express them, without any major effects on pattern formation. Ubx is generally expressed at higher levels in T3- relative to T2-legs in semi-aquatic insects. It is only in the derived Gerridae where the high levels of Ubx result in reduced T3-leg length. In the Gerridae, the response of leg tissues to Ubx levels is bimodal. Changes in Ubx regulation and function have evolved in Limnoporus without disrupting patterning hierarchies. Changes in Hox protein levels and emergence of tissue sensitivity to these levels can shape adaptive morphological traits.
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Affiliation(s)
- Peter Nagui Refki
- Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, 46 Allée d׳Italie, 69364 Lyon Cedex 07, France; Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
| | - David Armisén
- Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, 46 Allée d׳Italie, 69364 Lyon Cedex 07, France
| | - Antonin Jean Johan Crumière
- Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, 46 Allée d׳Italie, 69364 Lyon Cedex 07, France; Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
| | - Séverine Viala
- Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, 46 Allée d׳Italie, 69364 Lyon Cedex 07, France
| | - Abderrahman Khila
- Institut de Génomique Fonctionnelle de Lyon, CNRS-UMR5242, Ecole Normale Supérieure de Lyon, 46 Allée d׳Italie, 69364 Lyon Cedex 07, France.
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Khila A, Abouheif E, Rowe L. Comparative functional analyses of ultrabithorax reveal multiple steps and paths to diversification of legs in the adaptive radiation of semi-aquatic insects. Evolution 2014; 68:2159-70. [PMID: 24766229 DOI: 10.1111/evo.12444] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 04/14/2014] [Indexed: 01/16/2023]
Abstract
Invasion of new ecological habitats is often associated with lineage diversification, yet the genetic changes underlying invasions and radiations are poorly understood. Over 200 million years ago, the semi-aquatic insects invaded water surface from a common terrestrial ancestor and diversified to exploit a wide array of niches. Here, we uncover the changes in regulation and function of the gene Ultrabithorax associated with both the invasion of water surface and the subsequent diversification of the group. In the common ancestor of the semi-aquatic insects, a novel deployment of Ubx protein in the mid-legs increased their length, thereby enhancing their role in water surface walking. In derived lineages that specialize in rowing on the open water, additional changes in the timing of Ubx expression further elongated the mid-legs thereby facilitating their function as oars. In addition, Ubx protein function was selectively reversed to shorten specific rear-leg segments, thereby enabling their function as rudders. These changes in Ubx have generated distinct niche-specialized morphologies that account for the remarkable diversification of the semi-aquatic insects. Therefore, changes in the regulation and function of a key developmental gene may facilitate both the morphological change necessary to transition to novel habitats and fuel subsequent morphological diversification.
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Affiliation(s)
- Abderrahman Khila
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada; Department of Biology, McGill University, Stewart Biological Sciences Building, Montreal, Quebec H3A 1B1, Canada; Institut de Genomique Fonctionnelle de Lyon, Ecole Normale Supérieure, CNRS UMR 5242, 46 allée d'Italie, 69364 Lyon Cedex 07, France.
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24
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Medved V, Huang ZY, Popadic A. Ubx promotes corbicular development in Apis mellifera. Biol Lett 2014; 10:20131021. [PMID: 24478202 DOI: 10.1098/rsbl.2013.1021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The key morphological feature that distinguishes corbiculate bees from other members of the Apidae family is the presence of the corbicula (pollen basket) on the tibial segment of hind legs. Here, we show that in the honeybee (Apis mellifera), the depletion of the gene Ultrabithorax (Ubx) by RNAi transforms the corbicula from a smooth, bristle-free concave structure to one covered with bristles. This is accompanied by a reduction of the pollen press, which is located on the basitarsus and used for packing the pollen pellet as well as a loss of the orderly arrangement of the rows of bristles that form the pollen comb. All these changes make the overall identity of workers' T3 legs assume that of the queen. Furthermore, in a corbiculate bee of a different genus, Bombus impatiens, Ubx expression is also localized in T3 tibia and basitarsus. These observations suggest that the evolution of the pollen gathering apparatus in corbiculate bees may have a shared origin and could be traced to the acquisition of novel functions by Ubx, which in Apis were instrumental for subsequent castes and behavioural differentiation.
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Affiliation(s)
- Victor Medved
- Department of Biological Sciences, Wayne State University, , Detroit, MI, USA
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25
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Konopova B, Akam M. The Hox genes Ultrabithorax and abdominal-A specify three different types of abdominal appendage in the springtail Orchesella cincta (Collembola). EvoDevo 2014; 5:2. [PMID: 24398075 PMCID: PMC3910676 DOI: 10.1186/2041-9139-5-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/20/2013] [Indexed: 12/18/2022] Open
Abstract
Background In Drosophila and many other insects, the Hox genes Ultrabithorax (Ubx) and abdominal-A (abd-A) suppress limb formation on most or all segments of the abdomen. However, a number of basal hexapod lineages retain multiple appendages on the abdomen. In the collembolans or springtails, three abdominal segments develop specialized organs that originate from paired appendage primordia which fuse at the midline: the first abdominal segment bears the collophore (ventral tube), involved in osmoregulation; the fourth segment bears the furca, the leaping organ, and the third segment bears the retinaculum, which retains the furca at rest. Ubx and abd-A are known to be expressed in the springtail abdomen, but what role they play in specifying these distinct abdominal appendages is not known. This is largely because no genetic model has been established in collembolans or any other non-insect hexapod. Results We have developed a convenient method for laboratory culture of the collembolan Orchesella cincta on defined media, a method for in-situ hybridization to embryos and a procedure for gene knockdown by parental injection of double-stranded RNA (RNAi). We show that Orchesella Ubx transcripts are detectable in the first to third abdominal segments, and abd-A transcripts in the second to fourth segments. Knockdown of Oc-Ubx leads to the homeotic transformation of the collophore into a pair of walking legs (a more anterior identity) but the retinaculum into a furca (a more posterior identity). Knockdown of Oc-abd-A leads to the transformation of the retinaculum into a collophore and of the furca into legs (both anterior transformations). Simultaneous silencing of both Oc-Ubx and Oc-abd-A transformed all three of these appendages into paired legs, but did not cause appendages to develop on the second, or on the most posterior abdominal segments. Conclusions We conclude that, in Orchesella, Oc-Ubx alone specifies the collophore on the first and Oc-abd-A alone specifies the furca on the fourth abdominal segment. Oc-Ubx and Oc-abd-A function together, apparently combinatorially, to specify the retinaculum on the third segment. The efficiency of RNAi in Orchesella makes this an attractive model for further genetic studies of development and physiology in basal hexapods. Electronic supplementary material The online version of this article (doi:10.1186/2041-9139-5-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Barbora Konopova
- Laboratory for Development and Evolution, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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26
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Nijhout HF, Riddiford LM, Mirth C, Shingleton AW, Suzuki Y, Callier V. The developmental control of size in insects. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2014; 3:113-34. [PMID: 24902837 PMCID: PMC4048863 DOI: 10.1002/wdev.124] [Citation(s) in RCA: 190] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mechanisms that control the sizes of a body and its many parts remain among the great puzzles in developmental biology. Why do animals grow to a species-specific body size, and how is the relative growth of their body parts controlled to so they grow to the right size, and in the correct proportion with body size, giving an animal its species-characteristic shape? Control of size must involve mechanisms that somehow assess some aspect of size and are upstream of mechanisms that regulate growth. These mechanisms are now beginning to be understood in the insects, in particular in Manduca sexta and Drosophila melanogaster. The control of size requires control of the rate of growth and control of the cessation of growth. Growth is controlled by genetic and environmental factors. Insulin and ecdysone, their receptors, and intracellular signaling pathways are the principal genetic regulators of growth. The secretion of these growth hormones, in turn, is controlled by complex interactions of other endocrine and molecular mechanisms, by environmental factors such as nutrition, and by the physiological mechanisms that sense body size. Although the general mechanisms of growth regulation appear to be widely shared, the mechanisms that regulate final size can be quite diverse.
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27
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Warren IA, Gotoh H, Dworkin IM, Emlen DJ, Lavine LC. A general mechanism for conditional expression of exaggerated sexually-selected traits. Bioessays 2013; 35:889-99. [PMID: 23852854 DOI: 10.1002/bies.201300031] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sexually-selected exaggerated traits tend to be unusually reliable signals of individual condition, as their expression tends to be more sensitive to nutritional history and physiological circumstance than that of other phenotypes. As such, these traits are the foundation for many models of sexual selection and animal communication, such as "handicap" and "good genes" models. Exactly how expression of these traits is linked to the bearer's condition has been a central yet unresolved question, in part because the underlying physiological mechanisms regulating their development have remained largely unknown. Recent discoveries across animals as diverse as deer, beetles, and flies now implicate the widely conserved insulin-like signaling pathway, as a common physiological mechanism regulating condition-sensitive structures with extreme growth. This raises the exciting possibility that one highly conserved pathway may underlie the evolution of trait exaggeration in a multitude of sexually-selected signal traits across the animal kingdom.
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Affiliation(s)
- Ian A Warren
- School of Biological Sciences, University of Bristol, UK
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28
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Sharma PP, Schwager EE, Giribet G, Jockusch EL, Extavour CG. Distal-lessanddachshundpattern both plesiomorphic and apomorphic structures in chelicerates: RNA interference in the harvestmanPhalangium opilio(Opiliones). Evol Dev 2013; 15:228-42. [DOI: 10.1111/ede.12029] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Evelyn E. Schwager
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street, Cambridge, MA 02138; USA
| | | | - Elizabeth L. Jockusch
- Department of Ecology and Evolutionary Biology; University of Connecticut; 75 N. Eagleville Road, Storrs, CT 06269; USA
| | - Cassandra G. Extavour
- Department of Organismic and Evolutionary Biology; Harvard University; 26 Oxford Street, Cambridge, MA 02138; USA
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29
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Heffer A, Pick L. Conservation and variation in Hox genes: how insect models pioneered the evo-devo field. ANNUAL REVIEW OF ENTOMOLOGY 2013; 58:161-179. [PMID: 23317041 DOI: 10.1146/annurev-ento-120811-153601] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Evolutionary developmental biology, or evo-devo, broadly investigates how body plan diversity and morphological novelties have arisen and persisted in nature. The discovery of Hox genes in Drosophila, and their subsequent identification in most other metazoans, led biologists to try to understand how embryonic genes crucial for proper development have changed to promote the vast morphological variation seen in nature. Insects are ideal model systems for studying this diversity and the mechanisms underlying it because phylogenetic relationships are well established, powerful genetic tools have been developed, and there are many examples of evolutionary specializations that have arisen in nature in different insect lineages, such as the jumping leg of orthopterans and the helmet structures of treehoppers. Here, we briefly introduce the field of evo-devo and Hox genes, discuss functional tools available to study early developmental genes in insects, and provide examples in which changes in Hox genes have contributed to changes in body plan or morphology.
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Affiliation(s)
- Alison Heffer
- Department of Entomology and Program in Molecular & Cell Biology, University of Maryland, College Park, Maryland 20742, USA
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Divergent role of the Hox gene Antennapedia in spiders is responsible for the convergent evolution of abdominal limb repression. Proc Natl Acad Sci U S A 2012; 109:4921-6. [PMID: 22421434 DOI: 10.1073/pnas.1116421109] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Evolution often results in morphologically similar solutions in different organisms, a phenomenon known as convergence. However, there is little knowledge of the processes that lead to convergence at the genetic level. The genes of the Hox cluster control morphology in animals. They may also be central to the convergence of morphological traits, but whether morphological similarities also require similar changes in Hox gene function is disputed. In arthropods, body subdivision into a region with locomotory appendages ("thorax") and a region with reduced appendages ("abdomen") has evolved convergently in several groups, e.g., spiders and insects. In insects, legs develop in the expression domain of the Hox gene Antennapedia (Antp), whereas the Hox genes Ultrabithorax (Ubx) and abdominal-A mediate leg repression in the abdomen. Here, we show that, unlike Antp in insects, the Antp gene in the spider Achaearanea tepidariorum represses legs in the first segment of the abdomen (opisthosoma), and that Antp and Ubx are redundant in the following segment. The down-regulation of Antp in A. tepidariorum leads to a striking 10-legged phenotype. We present evidence from ectopic expression of the spider Antp gene in Drosophila embryos and imaginal tissue that this unique function of Antp is not due to changes in the Antp protein, but likely due to divergent evolution of cofactors, Hox collaborators or target genes in spiders and flies. Our results illustrate an interesting example of convergent evolution of abdominal leg repression in arthropods by altering the role of distinct Hox genes at different levels of their action.
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Progressive tarsal patterning in the Drosophila by temporally dynamic regulation of transcription factor genes. Dev Biol 2012; 361:450-62. [DOI: 10.1016/j.ydbio.2011.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 10/24/2011] [Accepted: 10/25/2011] [Indexed: 10/15/2022]
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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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Chen B, Hrycaj S, Schinko JB, Podlaha O, Wimmer EA, Popadić A, Monteiro A. Pogostick: a new versatile piggyBac vector for inducible gene over-expression and down-regulation in emerging model systems. PLoS One 2011; 6:e18659. [PMID: 21533190 PMCID: PMC3077399 DOI: 10.1371/journal.pone.0018659] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 03/07/2011] [Indexed: 11/18/2022] Open
Abstract
Background Non-traditional model systems need new tools that will enable them to enter the field of functional genetics. These tools should enable the exploration of gene function, via knock-downs of endogenous genes, as well as over-expression and ectopic expression of transgenes. Methodology We constructed a new vector called Pogostick that can be used to over-express or down-regulate genes in organisms amenable to germ line transformation by the piggyBac transposable element. Pogostick can be found at www.addgene.org, a non-profit plasmid repository. The vector currently uses the heat-shock promoter Hsp70 from Drosophila to drive transgene expression and, as such, will have immediate applicability to organisms that can correctly interpret this promotor sequence. We detail how to clone candidate genes into this vector and test its functionality in Drosophila by targeting a gene coding for the fluorescent protein DsRed. By cloning a single DsRed copy into the vector, and generating transgenic lines, we show that DsRed mRNA and protein levels are elevated following heat-shock. When cloning a second copy of DsRed in reverse orientation into a flanking site, and transforming flies constitutively expressing DsRed in the eyes, we show that endogenous mRNA and protein levels drop following heat-shock. We then test the over-expression vector, containing the complete cDNA of Ultrabithorax (Ubx) gene, in an emerging model system, Bicyclus anynana. We produce a transgenic line and show that levels of Ubx mRNA expression rise significantly following a heat-shock. Finally, we show how to obtain genomic sequence adjacent to the Pogostick insertion site and to estimate transgene copy number in genomes of transformed individuals. Significance This new vector will allow emerging model systems to enter the field of functional genetics with few hurdles.
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Affiliation(s)
- Bin Chen
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America
- Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, People's Republic of China
- * E-mail: (BC); (AM)
| | - Steven Hrycaj
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Johannes B. Schinko
- Department of Developmental Biology, Georg-August-University Göttingen, Göttingen, Germany
| | - Ondrej Podlaha
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America
| | - Ernst A. Wimmer
- Department of Developmental Biology, Georg-August-University Göttingen, Göttingen, Germany
| | - Aleksandar Popadić
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Antónia Monteiro
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America
- * E-mail: (BC); (AM)
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Wolfe JM, Oliver JC, Monteiro A. Evolutionary reduction of the first thoracic limb in butterflies. JOURNAL OF INSECT SCIENCE (ONLINE) 2011; 11:66. [PMID: 21867433 PMCID: PMC3281478 DOI: 10.1673/031.011.6601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 09/08/2010] [Indexed: 05/31/2023]
Abstract
Members of the diverse butterfly families Nymphalidae (brush-footed butterflies) and Riodinidae (metalmarks) have reduced first thoracic limbs and only use two pairs of legs for walking. In order to address questions about the detailed morphology and evolutionary origins of these reduced limbs, the three thoracic limbs of 13 species of butterflies representing all six butterfly families were examined and measured, and ancestral limb sizes were reconstructed for males and females separately. Differences in limb size across butterflies involve changes in limb segment size rather than number of limb segments. Reduction of the first limb in both nymphalids and riodinids appears particularly extensive in the femur, but the evolution of these reduced limbs is suggested to be a convergent evolutionary event. Possible developmental differences as well as ecological factors driving the evolution of reduced limbs are discussed.
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Affiliation(s)
- Joanna M. Wolfe
- Department of Geology & Geophysics, Yale University, New Haven, CT 06520-8109, USA
| | - Jeffrey C. Oliver
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT 06520-8106, USA
| | - Antónia Monteiro
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT 06520-8106, USA
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Wasik BR, Rose DJ, Moczek AP. Beetle horns are regulated by the Hox gene, Sex combs reduced, in a species- and sex-specific manner. Evol Dev 2010; 12:353-62. [DOI: 10.1111/j.1525-142x.2010.00422.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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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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Functional analysis of Ultrabithorax in the silkworm, Bombyx mori, using RNAi. Dev Genes Evol 2009; 219:437-44. [PMID: 19908062 DOI: 10.1007/s00427-009-0305-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 10/15/2009] [Indexed: 10/20/2022]
Abstract
The formation of abdominal appendages in insects is suppressed by the Hox genes Ultrabithorax (Ubx) and abdominal-A (abd-A), but mechanisms of the suppression can differ among species. As the function of Ubx and abd-A has been described in only a few species, more data from various insects are necessary to elucidate the evolutionary transition of regulation on abdominal appendages. We examined the function of Ubx in the silkworm Bombyx mori (Bm-Ubx) by embryonic RNA interference (RNAi). This is the first case in which functional analysis for Ubx is performed in lepidopteran insects. Larvae treated with Bm-Ubx dsRNA displayed an additional pair of thoracic leg-like protuberances in A1, whereas the other abdominal segments had no transformation. Our results suggest that Bm-Ubx is a suppressor of leg development in A1.
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Khila A, Abouheif E, Rowe L. Evolution of a novel appendage ground plan in water striders is driven by changes in the Hox gene Ultrabithorax. PLoS Genet 2009; 5:e1000583. [PMID: 19649305 PMCID: PMC2709915 DOI: 10.1371/journal.pgen.1000583] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 07/01/2009] [Indexed: 11/21/2022] Open
Abstract
Water striders, a group of semi-aquatic bugs adapted to life on the water surface, have evolved mid-legs (L2) that are long relative to their hind-legs (L3). This novel appendage ground plan is a derived feature among insects, where L2 function as oars and L3 as rudders. The Hox gene Ultrabithorax (Ubx) is known to increase appendage size in a variety of insects. Using gene expression and RNAi analysis, we discovered that Ubx is expressed in both L2 and L3, but Ubx functions to elongate L2 and to shorten L3 in the water strider Gerris buenoi. Therefore, within hemimetabolous insects, Ubx has evolved a new expression domain but maintained its ancestral elongating function in L2, whereas Ubx has maintained its ancestral expression domain but evolved a new shortening function in L3. These changes in Ubx expression and function may have been a key event in the evolution of the distinct appendage ground plan in water striders. Water striders are derived semi-aquatic bugs that possess a remarkable diversity of leg lengths and shapes among species and between sexes, and the selective forces shaping this diversity are well studied. The transition to living on the water surface was accompanied by dramatic changes in the size and function of their legs. The mid-legs are disproportionately long and function as oars, whereas the hind-legs are shorter and function as rudders. We present evidence demonstrating that changes in the pattern of expression and function of the Hox gene Ultrabithorax are responsible for establishing the relative size differences between mid- and hind-legs in the water strider Gerris buenoi. These changes in Ubx expression and function may have been a key event in the evolution of the distinct appendage ground plan in water striders.
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Affiliation(s)
- Abderrahman Khila
- Department of Biology, McGill University, Montreal, Quebec, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ehab Abouheif
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - Locke Rowe
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Chesebro J, Hrycaj S, Mahfooz N, Popadić A. Diverging functions of Scr between embryonic and post-embryonic development in a hemimetabolous insect, Oncopeltus fasciatus. Dev Biol 2009; 329:142-51. [PMID: 19382295 DOI: 10.1016/j.ydbio.2009.01.032] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hemimetabolous insects undergo an ancestral mode of development in which embryos hatch into first nymphs that resemble miniature adults. While recent studies have shown that homeotic (hox) genes establish segmental identity of first nymphs during embryogenesis, no information exists on the function of these genes during post-embryogenesis. To determine whether and to what degree hox genes influence the formation of adult morphologies, we performed a functional analysis of Sex combs reduced (Scr) during post-embryonic development in Oncopeltus fasciatus. The main effect was observed in prothorax of Scr-RNAi adults, and ranged from significant alterations in its size and shape to a near complete transformation of its posterior half toward a T2-like identity. Furthermore, while the consecutive application of Scr-RNAi at both of the final two post-embryonic stages (fourth and fifth) did result in formation of ectopic wings on T1, the individual applications at each of these stages did not. These experiments provide two new insights into evolution of wings. First, the role of Scr in wing repression appears to be conserved in both holo- and hemimetabolous insects. Second, the prolonged Scr-depletion (spanning at least two nymphal stages) is both necessary and sufficient to restart wing program. At the same time, other structures that were previously established during embryogenesis are either unaffected (T1 legs) or display only minor changes (labium) in adults. These observations reveal a temporal and spatial divergence of Scr roles during embryonic (main effect in labium) and post-embryonic (main effect in prothorax) development.
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Affiliation(s)
- John Chesebro
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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Hrycaj S, Mihajlovic M, Mahfooz N, Couso JP, Popadić A. RNAi analysis of nubbin embryonic functions in a hemimetabolous insect, Oncopeltus fasciatus. Evol Dev 2008; 10:705-16. [DOI: 10.1111/j.1525-142x.2008.00284.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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