| 1. |
- Aase-Remedios, Madeleine E., et al.
(författare)
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Evolution of the Spider Homeobox Gene Repertoire by Tandem and Whole Genome Duplication
- 2023
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Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 40:12
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Tidskriftsartikel (refereegranskat)abstract
- Gene duplication generates new genetic material that can contribute to the evolution of gene regulatory networks and phenotypes. Duplicated genes can undergo subfunctionalization to partition ancestral functions and/or neofunctionalization to assume a new function. We previously found there had been a whole genome duplication (WGD) in an ancestor of arachnopulmonates, the lineage including spiders and scorpions but excluding other arachnids like mites, ticks, and harvestmen. This WGD was evidenced by many duplicated homeobox genes, including two Hox clusters, in spiders. However, it was unclear which homeobox paralogues originated by WGD versus smaller-scale events such as tandem duplications. Understanding this is a key to determining the contribution of the WGD to arachnopulmonate genome evolution. Here we characterized the distribution of duplicated homeobox genes across eight chromosome-level spider genomes. We found that most duplicated homeobox genes in spiders are consistent with an origin by WGD. We also found two copies of conserved homeobox gene clusters, including the Hox, NK, HRO, Irx, and SINE clusters, in all eight species. Consistently, we observed one copy of each cluster was degenerated in terms of gene content and organization while the other remained more intact. Focussing on the NK cluster, we found evidence for regulatory subfunctionalization between the duplicated NK genes in the spider Parasteatoda tepidariorum compared to their single-copy orthologues in the harvestman Phalangium opilio. Our study provides new insights into the relative contributions of multiple modes of duplication to the homeobox gene repertoire during the evolution of spiders and the function of NK genes.
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| 2. |
- Budd, Graham, et al.
(författare)
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Comment on "The lower Cambrian lobopodian Cardiodictyon resolves the origin of euarthropod brains"
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6652
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Tidskriftsartikel (refereegranskat)abstract
- Strausfeld et al. (Report, 24 Nov 2022, p. 905) claim that Cambrian fossilized nervous tissue supports the interpretation that the ancestral panarthropod brain was tripartite and unsegmented. We argue that this conclusion is unsupported, and developmental data from living onychophorans contradict it.
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| 3. |
- Gasiorowski, Ludwik, et al.
(författare)
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Molecular evidence for a single origin of ultrafiltration-based excretory organs
- 2021
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Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 31:16, s. 3629-
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Tidskriftsartikel (refereegranskat)abstract
- Excretion is an essential physiological process, carried out by all living organisms, regardless of their size or complexity.(1-3) Both protostomes (e.g., flies and flatworms) and deuterostomes (e.g., humans and sea urchins) possess specialized excretory organs serving that purpose, Those organs exhibit an astonishing diversity, ranging from units composed of just few distinct cells (e.g., protonephridia) to complex structures, built by millions of cells of multiple types with divergent morphology and function (e.g., vertebrate kidneys).(4,5) Although some molecular similarities between the development of kidneys of vertebrates and the regeneration of the protonephridia of flatworms have been reported, (6,7) the molecular underpinnings of the development of excretory organs have never been systematically studied in a comparative context. (4) Here, we show that a set of transcription factors (eya, six1/2, pou3, sail, Ihx1/5, and osr) and structural proteins (nephrin, kirre, and zo1) is expressed in the excretory organs of a phoronid, brachiopod, annelid, onychophoran, priapulid, and hemichordate that represent major protostome lineages and non-vertebrate deuterostomes. We demonstrate that the molecular similarity observed in the vertebrate kidney and flatworm protonephridia(6,7) is also seen in the developing excretory organs of those animals. Our results show that all types of ultrafiltration-based excretory organs are patterned by a conserved set of developmental genes, an observation that supports their homology. We propose that the last common ancestor of protostomes and deuterostomes already possessed an ultrafiltration-based organ that later gave rise to the vast diversity of extant excretory organs, including both proto- and metanephridia.
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| 4. |
- Harper, Amber, et al.
(författare)
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Widespread retention of ohnologs in key developmental gene families following whole-genome duplication in arachnopulmonates
- 2021
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Ingår i: G3. - : Oxford University Press. - 2160-1836. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- Whole-genome duplications (WGDs) have occurred multiple times during animal evolution, including in lineages leading to vertebrates, teleosts, horseshoe crabs, and arachnopulmonates. These dramatic events initially produce a wealth of new genetic material, generally followed by extensive gene loss. It appears, however, that developmental genes such as homeobox genes, signaling pathway components and microRNAs are frequently retained as duplicates (so-called ohnologs) following WGD. These not only provide the best evidence for WGD, but an opportunity to study its evolutionary consequences. Although these genes are well studied in the context of vertebrate WGD, similar comparisons across the extant arachnopulmonate orders are patchy. We sequenced embryonic transcriptomes from two spider species and two amblypygid species and surveyed three important gene families, Hox, Wnt, and frizzled, across these and 12 existing transcriptomic and genomic resources for chelicerates. We report extensive retention of putative ohnologs, further supporting the ancestral arachnopulmonate WGD. We also found evidence of consistent evolutionary trajectories in Hox and Wnt gene repertoires across three of the six arachnopulmonate orders, with interorder variation in the retention of specific paralogs. We identified variation between major clades in spiders and are better able to reconstruct the chronology of gene duplications and losses in spiders, amblypygids, and scorpions. These insights shed light on the evolution of the developmental toolkit in arachnopulmonates, highlight the importance of the comparative approach within lineages, and provide substantial new transcriptomic data for future study.
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| 5. |
- Heingård, Miriam, et al.
(författare)
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The forkhead box containing transcription factor FoxB is a potential component of dorsal-ventral body axis formation in the spider Parasteatoda tepidariorum
- 2020
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Ingår i: Development, Genes and Evolution. - : SPRINGER. - 0949-944X .- 1432-041X. ; 230:2, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- In the spider, determination of the dorsal-ventral body (DV) axis depends on the interplay of the dorsal morphogen encoding gene decapentaplegic (Dpp) and its antagonist, short gastrulation (sog), a gene that is involved in the correct establishment of ventral tissues. Recent work demonstrated that the forkhead domain encoding gene FoxB is involved in dorsal-ventral axis formation in spider limbs. Here, Dpp likely acts as a dorsal morphogen, and FoxB is likely in control of ventral tissues as RNAi-mediated knockdown of FoxB causes dorsalization of the limbs. In this study, we present phenotypes of FoxB knockdown that demonstrate a function in the establishment of the DV body axis. Knockdown of FoxB function leads to embryos with partially duplicated median germ bands (Duplicitas media) that are possibly the result of ectopic activation of Dpp signalling. Another class of phenotypes is characterized by unnaturally slim (dorsal-ventrally compressed) germ bands in which ventral tissue is either not formed, or is specified incorrectly, likely a result of Dpp over-activity. These results suggest that FoxB functions as an antagonist of Dpp signalling during body axis patterning, similarly as it is the case in limb development. FoxB thus represents a general player in the establishment of dorsal-ventral structures during spider ontogeny.
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| 6. |
- Janssen, Ralf, 1975-, et al.
(författare)
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A chelicerate Wnt gene expression atlas : novel insights into the complexity of arthropod Wnt-patterning
- 2021
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Ingår i: EvoDevo. - : BioMed Central (BMC). - 2041-9139. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The Wnt genes represent a large family of secreted glycoprotein ligands that date back to early animal evolution. Multiple duplication events generated a set of 13 Wnt families of which 12 are preserved in protostomes. Embryonic Wnt expression patterns (Wnt-patterning) are complex, representing the plentitude of functions these genes play during development. Here, we comprehensively investigated the embryonic expression patterns of Wnt genes from three species of spiders covering both main groups of true spiders, Haplogynae and Entelegynae, a mygalomorph species (tarantula), as well as a distantly related chelicerate outgroup species, the harvestman Phalangium opilio. All spiders possess the same ten classes of Wnt genes, but retained partially different sets of duplicated Wnt genes after whole genome duplication, some of which representing impressive examples of sub- and neo-functionalization. The harvestman, however, possesses a more complete set of 11 Wnt genes but with no duplicates. Our comprehensive data-analysis suggests a high degree of complexity and evolutionary flexibility of Wnt-patterning likely providing a firm network of mutational protection. We discuss the new data on Wnt gene expression in terms of their potential function in segmentation, posterior elongation, and appendage development and critically review previous research on these topics. We conclude that earlier research may have suffered from the absence of comprehensive gene expression data leading to partial misconceptions about the roles of Wnt genes in development and evolution.
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| 7. |
- Janssen, Ralf, 1975-, et al.
(författare)
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A comprehensive study of arthropod and onychophoran Fox gene expression patterns
- 2022
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- Fox genes represent an evolutionary old class of transcription factor encoding genes that evolved in the last common ancestor of fungi and animals. They represent key-components of multiple gene regulatory networks (GRNs) that are essential for embryonic development. Most of our knowledge about the function of Fox genes comes from vertebrate research, and for arthropods the only comprehensive gene expression analysis is that of the fly Drosophila melanogaster. For other arthropods, only selected Fox genes have been investigated. In this study, we provide the first comprehensive gene expression analysis of arthropod Fox genes including representative species of all main groups of arthropods, Pancrustacea, Myriapoda and Chelicerata. We also provide the first comprehensive analysis of Fox gene expression in an onychophoran species. Our data show that many of the Fox genes likely retained their function during panarthropod evolution highlighting their importance in development. Comparison with published data from other groups of animals shows that this high degree of evolutionary conservation often dates back beyond the last common ancestor of Panarthropoda.
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| 8. |
- Janssen, Ralf, 1975-, et al.
(författare)
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Embryonic expression patterns of Wnt genes in the RTA-clade spider Cupiennius salei
- 2022
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Ingår i: Gene Expression Patterns. - : Elsevier. - 1567-133X .- 1872-7298. ; 44
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Tidskriftsartikel (refereegranskat)abstract
- Spiders represent widely used model organisms for chelicerate and even arthropod development and evolution. Wnt genes are important and evolutionary conserved factors that control and regulate numerous developmental processes. Recent studies comprehensively investigated the complement and expression of spider Wnt genes revealing conserved as well as diverged aspects of their expression and thus (likely) function among different groups of spiders representing Mygalomorphae (tarantulas), and both main groups of Araneae (true spiders) (Haplogynae/Synspermiata and Entelegynae). The allegedly most modern/derived group of entelegyne spiders is represented by the RTA-clade of which no comprehensive data on Wnt expression were available prior to this study. Here, we investigated the embryonic expression of all Wnt genes of the RTA-clade spider Cupiennius salei. We found that most of the Wnt expression patterns are conserved between Cupiennius and other spiders, especially more basally branching species. Surprisingly, most differences in Wnt gene expression are seen in the common model spider Parasteatoda tepidariorum (a non-RTA clade entelegyne species). These results show that data and conclusions drawn from research on one member of a group of animals (or any other organism) cannot necessarily be extrapolated to the group as a whole, and instead highlight the need for comprehensive taxon sampling.
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| 9. |
- Janssen, Ralf, 1975-, et al.
(författare)
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Expression of netrin and its receptors uncoordinated-5 and frazzled in arthropods and onychophorans suggests conserved and diverged functions in neuronal pathfinding and synaptogenesis
- 2023
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Ingår i: Developmental Dynamics. - : John Wiley & Sons. - 1058-8388 .- 1097-0177. ; 252:1, s. 172-185
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Tidskriftsartikel (refereegranskat)abstract
- Background Development of the nervous system and the correct connection of nerve cells require coordinated axonal pathfinding through an extracellular matrix. Outgrowing axons exhibit directional growth toward or away from external guidance cues such as Netrin. Guidance cues can be detected by growth cones that are located at the end of growing axons through membrane-bound receptors such as Uncoordianted-5 and Frazzled. Binding of Netrin causes reformation of the cytoskeleton and growth of the axon toward (or away from) the source of Netrin production. Results Here, we investigate the embryonic mRNA expression patterns of netrin genes and their potential receptors, uncoordinated-5 and frazzled in arthropod species that cover all main branches of Arthropoda, that is, Pancrustacea, Myriapoda, and Chelicerata. We also studied the expression patterns in a closely related outgroup species, the onychophoran Euperipatoides kanangrensis, and provide data on expression profiles of these genes in larval tissues of the fly Drosophila melanogaster including the brain and the imaginal disks. Conclusion Our data reveal conserved and diverged aspects of neuronal guidance in Drosophila with respect to the other investigated species and suggest a conserved function in nervous system patterning of the developing appendages.
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| 10. |
- Janssen, Ralf, 1975-, et al.
(författare)
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Expression of posterior Hox genes and opisthosomal appendage development in a mygalomorph spider
- 2023
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Ingår i: Development, Genes and Evolution. - : Springer. - 0949-944X .- 1432-041X. ; 233, s. 107-121
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Tidskriftsartikel (refereegranskat)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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