1
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Tajer B, Savage AM, Whited JL. The salamander blastema within the broader context of metazoan regeneration. Front Cell Dev Biol 2023; 11:1206157. [PMID: 37635872 PMCID: PMC10450636 DOI: 10.3389/fcell.2023.1206157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 07/26/2023] [Indexed: 08/29/2023] Open
Abstract
Throughout the animal kingdom regenerative ability varies greatly from species to species, and even tissue to tissue within the same organism. The sheer diversity of structures and mechanisms renders a thorough comparison of molecular processes truly daunting. Are "blastemas" found in organisms as distantly related as planarians and axolotls derived from the same ancestral process, or did they arise convergently and independently? Is a mouse digit tip blastema orthologous to a salamander limb blastema? In other fields, the thorough characterization of a reference model has greatly facilitated these comparisons. For example, the amphibian Spemann-Mangold organizer has served as an amazingly useful comparative template within the field of developmental biology, allowing researchers to draw analogies between distantly related species, and developmental processes which are superficially quite different. The salamander limb blastema may serve as the best starting point for a comparative analysis of regeneration, as it has been characterized by over 200 years of research and is supported by a growing arsenal of molecular tools. The anatomical and evolutionary closeness of the salamander and human limb also add value from a translational and therapeutic standpoint. Tracing the evolutionary origins of the salamander blastema, and its relatedness to other regenerative processes throughout the animal kingdom, will both enhance our basic biological understanding of regeneration and inform our selection of regenerative model systems.
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Affiliation(s)
| | | | - Jessica L. Whited
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, United States
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2
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Falcon F, Tanaka EM, Rodriguez-Terrones D. Transposon waves at the water-to-land transition. Curr Opin Genet Dev 2023; 81:102059. [PMID: 37343338 DOI: 10.1016/j.gde.2023.102059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023]
Abstract
The major transitions in vertebrate evolution are associated with significant genomic reorganizations. In contrast to the evolutionary processes that occurred at the origin of vertebrates or prior to the radiation of teleost fishes, no whole-genome duplication events occurred during the water-to-land transition, and it remains an open question how did genome dynamics contribute to this prominent evolutionary event. Indeed, the recent sequencing of sarcopterygian and amphibian genomes has revealed that the extant lineages immediately preceding and succeeding this transition harbor an exceptional number of transposable elements and it is tempting to speculate that these sequences might have catalyzed the adaptations that enabled vertebrates to venture into land. Here, we review the genome dynamics associated with the major transitions in vertebrate evolution and discuss how the highly repetitive genomic landscapes revealed by recent efforts to characterize the genomes of amphibians and sarcopterygians argue for turbulent genome dynamics occurring before the water-to-land transition and possibly enabling it.
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Affiliation(s)
- Francisco Falcon
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria. https://twitter.com/@FcoJFalcon
| | - Elly M Tanaka
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria.
| | - Diego Rodriguez-Terrones
- Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter, 1030, Vienna, Austria.
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3
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Zhang S, Zhang X, Zhang C, Xu S, Wang D, Guo C. Developmental Genetic Basis of Hoxd9 Homeobox Domain Deletion in Pampus argenteus Pelvic Fin Deficiency. Int J Mol Sci 2023; 24:11769. [PMID: 37511526 PMCID: PMC10380636 DOI: 10.3390/ijms241411769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/12/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
Pampus argenteus is important for commercial fishery catch species and is an emerging target for aquaculture production. Notably, P. argenteus has a bizarre morphology and lacks pelvic fins. However, the reason for the lack of pelvic fins remains unclear, ultimately leading to frequent upside-down floating of P. argenteus during breeding and marked consumption of physical energy. Some lineages, including whales, fugu, snakes, and seahorse, independently lost the pelvic appendages over evolutionary time. Do different taxa employ the same molecular genetic pathways when they independently evolve similar developmental morphologies? Through analysis of the gene responsible for appendage localization, Hoxd9, it was discovered that the Hox domain was absent in the Hoxd9 gene of P. argenteus, and the Hoxd9b gene lacked the Hox9 activation region, a feature not observed in the Hoxd9 gene of other fish species. Interestingly, those distinctive characteristics are not observed in the Hoxd9 gene of other fish species. To determine the association between the Hoxd9 gene characteristics and the pelvic fin deletion in P. argenteus, the full-length cDNA of the Hoxd9a gene was cloned, and morphological observations of the species' juveniles were performed using stereomicroscopy and scanning electron microscopy. Thereafter, the tissue localization of Hoxd9a in the species was analyzed at the gene and protein levels. Based on the results, deletion of the Hoxd9a structural domain possibly leads to disruptions in the protein translation and the pelvic fin localization in P. argenteus during its early ontogenetic developmental stage, resulting in the absence of pelvic fins.
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Affiliation(s)
- Shun Zhang
- School of Marine Science, Ningbo University, Ningbo 315211, China
- National Engineering Research Laboratory of Marine Biotechnology and Engineering, Ningbo University, Ningbo 315211, China
| | - Xiaodong Zhang
- School of Marine Science, Ningbo University, Ningbo 315211, China
- National Engineering Research Laboratory of Marine Biotechnology and Engineering, Ningbo University, Ningbo 315211, China
| | - Cheng Zhang
- School of Marine Science, Ningbo University, Ningbo 315211, China
- National Engineering Research Laboratory of Marine Biotechnology and Engineering, Ningbo University, Ningbo 315211, China
| | - Shanliang Xu
- School of Marine Science, Ningbo University, Ningbo 315211, China
- Key Laboratory of Applied Marine Biotechnology, Ningbo University, Chinese Ministry of Education, Ningbo 315211, China
| | - Danli Wang
- School of Marine Science, Ningbo University, Ningbo 315211, China
- Key Laboratory of Green Mariculture (Co-Construction by Ministry and Province), Ministry of Agriculture and Rural, Ningbo University, Ningbo 315211, China
| | - Chunyang Guo
- School of Marine Science, Ningbo University, Ningbo 315211, China
- Key Laboratory of Green Mariculture (Co-Construction by Ministry and Province), Ministry of Agriculture and Rural, Ningbo University, Ningbo 315211, China
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4
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Takeuchi T, Matsubara H, Minamitani F, Satoh Y, Tozawa S, Moriyama T, Maruyama K, Suzuki KIT, Shigenobu S, Inoue T, Tamura K, Agata K, Hayashi T. Newt Hoxa13 has an essential and predominant role in digit formation during development and regeneration. Development 2022; 149:274659. [DOI: 10.1242/dev.200282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/21/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The 5′Hox genes play crucial roles in limb development and specify regions in the proximal-distal axis of limbs. However, there is no direct genetic evidence that Hox genes are essential for limb development in non-mammalian tetrapods or for limb regeneration. Here, we produced single to quadruple Hox13 paralog mutants using the CRISPR/Cas9 system in newts (Pleurodeles waltl), which have strong regenerative capacities, and also produced germline mutants. We show that Hox13 genes are essential for digit formation in development, as in mice. In addition, Hoxa13 has a predominant role in digit formation, unlike in mice. The predominance is probably due to the restricted expression pattern of Hoxd13 in limb buds and the strong dependence of Hoxd13 expression on Hoxa13. Finally, we demonstrate that Hox13 genes are also necessary for digit formation in limb regeneration. Our findings reveal that the general function of Hox13 genes is conserved between limb development and regeneration, and across taxa. The predominance of Hoxa13 function both in newt limbs and fish fins, but not in mouse limbs, suggests a potential contribution of Hoxa13 function in fin-to-limb transition.
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Affiliation(s)
- Takashi Takeuchi
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Haruka Matsubara
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Fumina Minamitani
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Yukio Satoh
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Sayo Tozawa
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Tomoki Moriyama
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Kohei Maruyama
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Ken-ichi T. Suzuki
- Laboratory of Regeneration Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Shuji Shigenobu
- Laboratory of Regeneration Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Takeshi Inoue
- Department of Life Science, Faculty of Science, Gakushuin University, Toyoshima-Ku, Tokyo 171-8588, Japan
| | - Koji Tamura
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan
| | - Kiyokazu Agata
- Laboratory of Regeneration Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Life Science, Faculty of Science, Gakushuin University, Toyoshima-Ku, Tokyo 171-8588, Japan
| | - Toshinori Hayashi
- Division of Developmental Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
- Program of Biomedical Science, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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5
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Royle SR, Young JJ. Developmental biology: A 5'Hoxd-Gli3 balance in tetrapod axial polarity. Curr Biol 2021; 31:R1487-R1490. [PMID: 34813756 DOI: 10.1016/j.cub.2021.10.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Almost all living tetrapods exhibit postaxial dominance in digit formation, apart from urodele amphibians, which show preaxial dominance. Recent work shines light on the genetic differences between the two modes of limb development, suggesting that differences in 5'Hoxd expression, mediated by Gli3, may explain the switch in axial polarity.
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Affiliation(s)
- Samantha R Royle
- Department of Genetics, Balvatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
| | - John J Young
- Biology Department, Simmons University, Boston, MA 02115, USA.
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6
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Conserved Mechanisms, Novel Anatomies: The Developmental Basis of Fin Evolution and the Origin of Limbs. DIVERSITY 2021. [DOI: 10.3390/d13080384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The transformation of paired fins into tetrapod limbs is one of the most intensively scrutinized events in animal evolution. Early anatomical and embryological datasets identified distinctive morphological regions within the appendage and posed hypotheses about how the loss, gain, and transformation of these regions could explain the observed patterns of both extant and fossil appendage diversity. These hypotheses have been put to the test by our growing understanding of patterning mechanisms that regulate formation of the appendage axes, comparisons of gene expression data from an array of phylogenetically informative taxa, and increasingly sophisticated and elegant experiments leveraging the latest molecular approaches. Together, these data demonstrate the remarkable conservation of developmental mechanisms, even across phylogenetically and morphologically disparate taxa, as well as raising new questions about the way we view homology, evolutionary novelty, and the often non-linear connection between morphology and gene expression. In this review, we present historical hypotheses regarding paired fin evolution and limb origins, summarize key aspects of central appendage patterning mechanisms in model and non-model species, address how modern comparative developmental data interface with our understanding of appendage anatomy, and highlight new approaches that promise to provide new insight into these well-traveled questions.
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7
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Hong Q, Li XD, Xie P, Du SX. All-trans-retinoic acid suppresses rat embryo hindlimb bud mesenchymal chondrogenesis by modulating HoxD9 expression. Bioengineered 2021; 12:3900-3911. [PMID: 34288810 PMCID: PMC8806522 DOI: 10.1080/21655979.2021.1940613] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In vertebrates, 5ʹ-Hoxd genes (Hoxd9), which are expressed in the hindlimb bud mesenchyme, participate in limb growth and patterning in early embryonic development. In the present study, We investigated the mechanisms by which ATRA regulates cultured E12.5 rat embryo hindlimb bud mesenchymal cells (rEHBMCs). Following exposure to ATRA over 24 h, mRNA and protein expression levels of HoxD9 were evaluated by reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), and western blotting. Flow cytometry was used to detect apoptosis. ATRA inhibited the condensation and proliferation, and promoted the apoptosis rate of the rEHBMCs in a dose-dependent manner. Sox9 and Col2a1 in rEHBMCs were downregulated by ATRA in a dose-dependent manner at both mRNA and protein levels. Similarly, HoxD9 was downregulated by ATRA in a dose-dependent manner, in parallel with the cartilage-specific molecules Sox9 and Col2a1. Both qPCR and western blotting showed that both Shh and Gli3 were downregulated. Overexpression of HoxD9 reversed the effects of ATRA. These results demonstrate that ATRA suppresses chondrogenesis in rEHBMCs by inhibiting the expression of HoxD9 and its downstream protein targets, including Sox9 and Col2a1. This effect may also be correlated with inhibition of the Shh-Gli3 signaling pathway.
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Affiliation(s)
- Quan Hong
- Department of Orthopedics, Jieyang People's Hospital (Jieyang Affiliated Hospital, Sun Yat-sen University), Jieyang, Guangdong, China
| | - Xue-Dong Li
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
| | - Peng Xie
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
| | - Shi-Xin Du
- Department of Orthopedics, Shenzhen Luohu Hospital Group Luohu People's Hospital (The Third Affiliated Hospital of Shenzhen University), Shenzhen, Guangdong, China
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8
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Spiny and soft-rayed fin domains in acanthomorph fish are established through a BMP- gremlin- shh signaling network. Proc Natl Acad Sci U S A 2021; 118:2101783118. [PMID: 34230098 DOI: 10.1073/pnas.2101783118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
With over 18,000 species, the Acanthomorpha, or spiny-rayed fishes, form the largest and arguably most diverse radiation of vertebrates. One of the key novelties that contributed to their evolutionary success are the spiny rays in their fins that serve as a defense mechanism. We investigated the patterning mechanisms underlying the differentiation of median fin Anlagen into discrete spiny and soft-rayed domains during the ontogeny of the direct-developing cichlid fish Astatotilapia burtoni Distinct transcription factor signatures characterize these two fin domains, whereby mutually exclusive expression of hoxa13a/b with alx4a/b and tbx2b marks the spine to soft-ray boundary. The soft-ray domain is established by BMP inhibition via gremlin1b, which synergizes in the posterior fin with shh secreted from a zone of polarizing activity. Modulation of BMP signaling by chemical inhibition or gremlin1b CRISPR/Cas9 knockout induces homeotic transformations of spines into soft rays and vice versa. The expression of spine and soft-ray genes in nonacanthomorph fins indicates that a combination of exaptation and posterior expansion of an ancestral developmental program for the anterior fin margin allowed the evolution of robustly individuated spiny and soft-rayed domains. We propose that a repeated exaptation of such pattern might underly the convergent evolution of anterior spiny-fin elements across fishes.
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9
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Onimaru K, Tatsumi K, Tanegashima C, Kadota M, Nishimura O, Kuraku S. Developmental hourglass and heterochronic shifts in fin and limb development. eLife 2021; 10:62865. [PMID: 33560225 PMCID: PMC7932699 DOI: 10.7554/elife.62865] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 02/01/2021] [Indexed: 11/13/2022] Open
Abstract
How genetic changes are linked to morphological novelties and developmental constraints remains elusive. Here, we investigate genetic apparatuses that distinguish fish fins from tetrapod limbs by analyzing transcriptomes and open-chromatin regions (OCRs). Specifically, we compared mouse forelimb buds with the pectoral fin buds of an elasmobranch, the brown-banded bamboo shark (Chiloscyllium punctatum). A transcriptomic comparison with an accurate orthology map revealed both a mass heterochrony and hourglass-shaped conservation of gene expression between fins and limbs. Furthermore, open-chromatin analysis suggested that access to conserved regulatory sequences is transiently increased during mid-stage limb development. During this stage, stage-specific and tissue-specific OCRs were also enriched. Together, early and late stages of fin/limb development are more permissive to mutations than middle stages, which may have contributed to major morphological changes during the fin-to-limb evolution. We hypothesize that the middle stages are constrained by regulatory complexity that results from dynamic and tissue-specific transcriptional controls. Animals come in all shapes and sizes. This diversity arose through genetic mutations during evolution, but it is unclear exactly how these variations led to the formation of new shapes. There is increasing evidence to suggest that not all shapes are possible and that variability between animals is limited by a phenomenon known as “developmental constraint”. These limitations direct parts of the body towards a specific shape as they develop in the embryo. Therefore, understanding the mechanisms underlying these developmental constraints could help explain how different body shapes evolved. The limbs of humans and other mammals evolved from the fins of fish, and this transition is often used to study the role developmental constraints play in evolution. This is an ideal model as there is already a detailed fossil record mapping this evolutionary event, and data pinpointing some of the genes involved in the development of limbs and fins. But this data is incomplete, and a full comparison between the genes activated in the fin and the limb during embryonic development had not been achieved. This is because most fish used for research have undergone recent genetic changes, making it hard to spot which genetic differences are linked to the evolution of the limb. To overcome this barrier, Onimaru et al. compared genetic data from the developing limbs of mice to the developing fins of the brown-banded bamboo shark, which evolves much slower than other fish. This revealed that although many genes commonly played a role in the development of the fin and the limb in the embryo, the activity of these shared genes was not the same. For example, genes that switched on in the late stages of limb development, switched off in the late stages of fin development. But in the middle of development, those differences were relatively small and both species activated very similar sets of genes. Many of these genes were pleiotropic, which means they have important roles in other tissues and therefore mutate less often. This suggests that the mid-stage of limb development is under the strongest level of constraint. Darwin’s theory of natural selection explains that mutations drive evolution. But the theory cannot predict what kinds of new body shapes new mutations will produce. Understanding how the activity levels of different genes affect development could help to fill this knowledge gap. This has potential medical applications, for example, understanding why some genetic changes cause more serious problems than others. This work suggests that mutations in genes that are active during the mid-stage of limb development may have the most serious impact.
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Affiliation(s)
- Koh Onimaru
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan.,Laboratory for Bioinformatics Research, RIKEN BDR, Wako City, Japan.,Molecular Oncology Laboratory, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Kaori Tatsumi
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Chiharu Tanegashima
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Mitsutaka Kadota
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Osamu Nishimura
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
| | - Shigehiro Kuraku
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan
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10
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Meyer A, Schloissnig S, Franchini P, Du K, Woltering JM, Irisarri I, Wong WY, Nowoshilow S, Kneitz S, Kawaguchi A, Fabrizius A, Xiong P, Dechaud C, Spaink HP, Volff JN, Simakov O, Burmester T, Tanaka EM, Schartl M. Giant lungfish genome elucidates the conquest of land by vertebrates. Nature 2021; 590:284-289. [PMID: 33461212 PMCID: PMC7875771 DOI: 10.1038/s41586-021-03198-8] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 01/06/2021] [Indexed: 01/29/2023]
Abstract
Lungfishes belong to lobe-fined fish (Sarcopterygii) that, in the Devonian period, 'conquered' the land and ultimately gave rise to all land vertebrates, including humans1-3. Here we determine the chromosome-quality genome of the Australian lungfish (Neoceratodus forsteri), which is known to have the largest genome of any animal. The vast size of this genome, which is about 14× larger than that of humans, is attributable mostly to huge intergenic regions and introns with high repeat content (around 90%), the components of which resemble those of tetrapods (comprising mainly long interspersed nuclear elements) more than they do those of ray-finned fish. The lungfish genome continues to expand independently (its transposable elements are still active), through mechanisms different to those of the enormous genomes of salamanders. The 17 fully assembled lungfish macrochromosomes maintain synteny to other vertebrate chromosomes, and all microchromosomes maintain conserved ancient homology with the ancestral vertebrate karyotype. Our phylogenomic analyses confirm previous reports that lungfish occupy a key evolutionary position as the closest living relatives to tetrapods4,5, underscoring the importance of lungfish for understanding innovations associated with terrestrialization. Lungfish preadaptations to living on land include the gain of limb-like expression in developmental genes such as hoxc13 and sall1 in their lobed fins. Increased rates of evolution and the duplication of genes associated with obligate air-breathing, such as lung surfactants and the expansion of odorant receptor gene families (which encode proteins involved in detecting airborne odours), contribute to the tetrapod-like biology of lungfishes. These findings advance our understanding of this major transition during vertebrate evolution.
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Affiliation(s)
- Axel Meyer
- Department of Biology, University of Konstanz, Konstanz, Germany.
| | | | - Paolo Franchini
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Kang Du
- Developmental Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, TX, USA
| | | | - Iker Irisarri
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
- Department of Applied Bioinformatics, Institute for Microbiology and Genetics, University of Goettingen, Goettingen, Germany
| | - Wai Yee Wong
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | | | - Susanne Kneitz
- Biochemistry and Cell Biology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Akane Kawaguchi
- Research Institute of Molecular Pathology (IMP), Vienna, Austria
| | | | - Peiwen Xiong
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Corentin Dechaud
- Institut de Génomique Fonctionnelle, École Normale Superieure, Université Claude Bernard, Lyon, France
| | - Herman P Spaink
- Faculty of Science, Universiteit Leiden, Leiden, The Netherlands
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle, École Normale Superieure, Université Claude Bernard, Lyon, France
| | - Oleg Simakov
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria.
| | | | - Elly M Tanaka
- Research Institute of Molecular Pathology (IMP), Vienna, Austria.
| | - Manfred Schartl
- Developmental Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany.
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, TX, USA.
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11
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Woltering JM, Irisarri I, Ericsson R, Joss JMP, Sordino P, Meyer A. Sarcopterygian fin ontogeny elucidates the origin of hands with digits. SCIENCE ADVANCES 2020; 6:eabc3510. [PMID: 32875118 PMCID: PMC7438105 DOI: 10.1126/sciadv.abc3510] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/09/2020] [Indexed: 05/03/2023]
Abstract
How the hand and digits originated from fish fins during the Devonian fin-to-limb transition remains unsolved. Controversy in this conundrum stems from the scarcity of ontogenetic data from extant lobe-finned fishes. We report the patterning of an autopod-like domain by hoxa13 during fin development of the Australian lungfish, the most closely related extant fish relative of tetrapods. Differences from tetrapod limbs include the absence of digit-specific expansion of hoxd13 and hand2 and distal limitation of alx4 and pax9, which potentially evolved through an enhanced response to shh signaling in limbs. These developmental patterns indicate that the digit program originated in postaxial fin radials and later expanded anteriorly inside of a preexisting autopod-like domain during the evolution of limbs. Our findings provide a genetic framework for the transition of fins into limbs that supports the significance of classical models proposing a bending of the tetrapod metapterygial axis.
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Affiliation(s)
- Joost M. Woltering
- Zoology and Evolutionary Biology, Department of Biology, Universität Konstanz, Universitätstrasse 10, 78464 Konstanz, Germany
| | - Iker Irisarri
- Zoology and Evolutionary Biology, Department of Biology, Universität Konstanz, Universitätstrasse 10, 78464 Konstanz, Germany
| | | | | | - Paolo Sordino
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Axel Meyer
- Zoology and Evolutionary Biology, Department of Biology, Universität Konstanz, Universitätstrasse 10, 78464 Konstanz, Germany
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