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Lyu H, Moya ND, Andersen EC, Chamberlin HM. Gene duplication and evolutionary plasticity of lin-12/Notch gene function in Caenorhabditis. Genetics 2024:iyae064. [PMID: 38809718 DOI: 10.1093/genetics/iyae064] [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: 01/10/2024] [Accepted: 04/16/2024] [Indexed: 05/31/2024] Open
Abstract
Gene duplication is an important substrate for the evolution of new gene functions, but the impacts of gene duplicates on their own activities and on the developmental networks in which they act are poorly understood. Here, we use a natural experiment of lin-12/Notch gene duplication within the nematode genus Caenorhabditis, combined with characterization of loss- and gain-of-function mutations, to uncover functional distinctions between the duplicate genes in 1 species (Caenorhabditis briggsae) and their single-copy ortholog in Caenorhabditis elegans. First, using improved genomic sequence and gene model characterization, we confirm that the C. briggsae genome includes 2 complete lin-12 genes, whereas most other genes encoding proteins that participate in the LIN-12 signaling pathway retain a one-to-one orthology with C. elegans. We use CRISPR-mediated genome editing to introduce alleles predicted to cause gain-of-function (gf) or loss-of-function (lf) into each C. briggsae gene and find that the gf mutations uncover functional distinctions not apparent from the lf alleles. Specifically, Cbr-lin-12.1(gf), but not Cbr-lin-12.2(gf), causes developmental defects similar to those observed in Cel-lin-12(gf). In contrast to Cel-lin-12(gf), however, the Cbr-lin-12.1(gf) alleles do not cause dominant phenotypes as compared to the wild type, and the mutant phenotype is observed only when 2 gf alleles are present. Our results demonstrate that gene duplicates can exhibit differential capacities to compensate for each other and to interfere with normal development, and uncover coincident gene duplication and evolution of developmental sensitivity to LIN-12/Notch activity.
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Affiliation(s)
- Haimeng Lyu
- Department of Molecular Genetics, Ohio State University, 484 W 12th Ave, Columbus, OH 43210, USA
| | - Nicolas D Moya
- Department of Biology, Johns Hopkins University, Bascom UTL 383, 3400 North Charles St., Baltimore, MD 21218, USA
| | - Erik C Andersen
- Department of Biology, Johns Hopkins University, Bascom UTL 383, 3400 North Charles St., Baltimore, MD 21218, USA
| | - Helen M Chamberlin
- Department of Molecular Genetics, Ohio State University, 484 W 12th Ave, Columbus, OH 43210, USA
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Evolutionary Dynamics of the SKN-1 → MED → END-1,3 Regulatory Gene Cascade in Caenorhabditis Endoderm Specification. G3-GENES GENOMES GENETICS 2020; 10:333-356. [PMID: 31740453 PMCID: PMC6945043 DOI: 10.1534/g3.119.400724] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Gene regulatory networks and their evolution are important in the study of animal development. In the nematode, Caenorhabditis elegans, the endoderm (gut) is generated from a single embryonic precursor, E. Gut is specified by the maternal factor SKN-1, which activates the MED → END-1,3 → ELT-2,7 cascade of GATA transcription factors. In this work, genome sequences from over two dozen species within the Caenorhabditis genus are used to identify MED and END-1,3 orthologs. Predictions are validated by comparison of gene structure, protein conservation, and putative cis-regulatory sites. All three factors occur together, but only within the Elegans supergroup, suggesting they originated at its base. The MED factors are the most diverse and exhibit an unexpectedly extensive gene amplification. In contrast, the highly conserved END-1 orthologs are unique in nearly all species and share extended regions of conservation. The END-1,3 proteins share a region upstream of their zinc finger and an unusual amino-terminal poly-serine domain exhibiting high codon bias. Compared with END-1, the END-3 proteins are otherwise less conserved as a group and are typically found as paralogous duplicates. Hence, all three factors are under different evolutionary constraints. Promoter comparisons identify motifs that suggest the SKN-1, MED, and END factors function in a similar gut specification network across the Elegans supergroup that has been conserved for tens of millions of years. A model is proposed to account for the rapid origin of this essential kernel in the gut specification network, by the upstream intercalation of duplicate genes into a simpler ancestral network.
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3
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Stevens L, Félix M, Beltran T, Braendle C, Caurcel C, Fausett S, Fitch D, Frézal L, Gosse C, Kaur T, Kiontke K, Newton MD, Noble LM, Richaud A, Rockman MV, Sudhaus W, Blaxter M. Comparative genomics of 10 new Caenorhabditis species. Evol Lett 2019; 3:217-236. [PMID: 31007946 PMCID: PMC6457397 DOI: 10.1002/evl3.110] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 02/08/2019] [Accepted: 02/25/2019] [Indexed: 01/29/2023] Open
Abstract
The nematode Caenorhabditis elegans has been central to the understanding of metazoan biology. However, C. elegans is but one species among millions and the significance of this important model organism will only be fully revealed if it is placed in a rich evolutionary context. Global sampling efforts have led to the discovery of over 50 putative species from the genus Caenorhabditis, many of which await formal species description. Here, we present species descriptions for 10 new Caenorhabditis species. We also present draft genome sequences for nine of these new species, along with a transcriptome assembly for one. We exploit these whole-genome data to reconstruct the Caenorhabditis phylogeny and use this phylogenetic tree to dissect the evolution of morphology in the genus. We reveal extensive variation in genome size and investigate the molecular processes that underlie this variation. We show unexpected complexity in the evolutionary history of key developmental pathway genes. These new species and the associated genomic resources will be essential in our attempts to understand the evolutionary origins of the C. elegans model.
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Affiliation(s)
- Lewis Stevens
- Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological SciencesUniversity of EdinburghEdinburghEH9 3JTUnited Kingdom
| | - Marie‐Anne Félix
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale SupérieureParis Sciences et Lettres75005ParisFrance
| | - Toni Beltran
- MRC London Institute of Medical SciencesLondonW12 0NNUnited Kingdom
| | - Christian Braendle
- Université Côte d'Azur, Centre National de la Recherche Scientifique, InsermInstitute of Biology Valrose06108NiceFrance
| | - Carlos Caurcel
- Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological SciencesUniversity of EdinburghEdinburghEH9 3JTUnited Kingdom
| | - Sarah Fausett
- Université Côte d'Azur, Centre National de la Recherche Scientifique, InsermInstitute of Biology Valrose06108NiceFrance
| | - David Fitch
- Department of BiologyNew York UniversityNew YorkNew York10003
| | - Lise Frézal
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale SupérieureParis Sciences et Lettres75005ParisFrance
| | - Charlie Gosse
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale SupérieureParis Sciences et Lettres75005ParisFrance
| | - Taniya Kaur
- Center for Genomics and Systems Biology, Department of BiologyNew York UniversityNew YorkNew York10003
| | - Karin Kiontke
- Department of BiologyNew York UniversityNew YorkNew York10003
| | - Matthew D. Newton
- MRC London Institute of Medical SciencesLondonW12 0NNUnited Kingdom
- Molecular Virology, Department of MedicineImperial College LondonDu Cane RoadLondonW12 0NNUnited Kingdom
| | - Luke M. Noble
- Center for Genomics and Systems Biology, Department of BiologyNew York UniversityNew YorkNew York10003
| | - Aurélien Richaud
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, École Normale SupérieureParis Sciences et Lettres75005ParisFrance
| | - Matthew V. Rockman
- Center for Genomics and Systems Biology, Department of BiologyNew York UniversityNew YorkNew York10003
| | - Walter Sudhaus
- Institut für Biologie/ZoologieFreie Universität BerlinBerlinD‐14195Germany
| | - Mark Blaxter
- Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological SciencesUniversity of EdinburghEdinburghEH9 3JTUnited Kingdom
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4
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Origination and evolution of orphan genes and de novo genes in the genome of Caenorhabditis elegans. SCIENCE CHINA-LIFE SCIENCES 2019; 62:579-593. [DOI: 10.1007/s11427-019-9482-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 12/31/2022]
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Dawes AT, Wu D, Mahalak KK, Zitnik EM, Kravtsova N, Su H, Chamberlin HM. A computational model predicts genetic nodes that allow switching between species-specific responses in a conserved signaling network. Integr Biol (Camb) 2017; 9:156-166. [DOI: 10.1039/c6ib00238b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alterations to only specific parameters in a model including EGF, Wnt and Notch lead to cell behavior differences.
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Affiliation(s)
- Adriana T. Dawes
- Department of Mathematics
- Ohio State University
- Columbus
- USA
- Department of Molecular Genetics
| | - David Wu
- Department of Mathematics
- Ohio State University
- Columbus
- USA
| | - Karley K. Mahalak
- Department of Molecular Genetics
- Ohio State University
- Columbus
- USA
- Graduate Program in Molecular
| | - Edward M. Zitnik
- Department of Molecular Genetics
- Ohio State University
- Columbus
- USA
| | - Natalia Kravtsova
- Department of Mathematics
- Ohio State University
- Columbus
- USA
- Department of Statistics
| | - Haiwei Su
- Department of Mathematics
- Ohio State University
- Columbus
- USA
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Conserved mechanism of Wnt signaling function in the specification of vulval precursor fates in C. elegans and C. briggsae. Dev Biol 2010; 346:128-39. [PMID: 20624381 DOI: 10.1016/j.ydbio.2010.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 06/17/2010] [Accepted: 07/01/2010] [Indexed: 01/29/2023]
Abstract
The C. elegans hermaphrodite vulva serves as a paradigm for understanding how signaling pathways control organ formation. Previous studies have shown that Wnt signaling plays important roles in vulval development. To understand the function and evolution of Wnt signaling in Caenorhabditis nematodes we focused on C. briggsae, a species that is substantially divergent from C. elegans in terms of the evolutionary time scale yet shares almost identical morphology. We isolated mutants in C. briggsae that display multiple pseudo-vulvae resulting from ectopic VPC induction. We cloned one of these loci and found that it encodes an Axin homolog, Cbr-PRY-1. Our genetic studies revealed that Cbr-pry-1 functions upstream of the canonical Wnt pathway components Cbr-bar-1 (beta-catenin) and Cbr-pop-1(tcf/lef) as well as the Hox target Cbr-lin-39 (Dfd/Scr). We further characterized the pry-1 vulval phenotype in C. briggsae and C. elegans using 8 cell fate markers, cell ablation, and genetic interaction approaches. Our results show that ectopically induced VPCs in pry-1 mutants adopt 2° fates independently of the gonad-derived inductive and LIN-12/Notch-mediated lateral signaling pathways. We also found that Cbr-pry-1 mutants frequently show a failure of P7.p induction. A similar, albeit low penetrant, defect is also observed in C. elegans pry-1 mutants. The genetic analysis of the P7.p induction defect revealed that it was caused by altered regulation of lin-12 and its transcriptional target lip-1 (MAP kinase phosphatase). Thus, our results provide evidence for LIN-12/Notch-dependent and independent roles of Wnt signaling in promoting 2 degrees VPC fates in both nematode species.
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Koboldt DC, Staisch J, Thillainathan B, Haines K, Baird SE, Chamberlin HM, Haag ES, Miller RD, Gupta BP. A toolkit for rapid gene mapping in the nematode Caenorhabditis briggsae. BMC Genomics 2010; 11:236. [PMID: 20385026 PMCID: PMC2864247 DOI: 10.1186/1471-2164-11-236] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 04/13/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The nematode C. briggsae serves as a useful model organism for comparative analysis of developmental and behavioral processes. The amenability of C. briggsae to genetic manipulations and the availability of its genome sequence have prompted researchers to study evolutionary changes in gene function and signaling pathways. These studies rely on the availability of forward genetic tools such as mutants and mapping markers. RESULTS We have computationally identified more than 30,000 polymorphisms (SNPs and indels) in C. briggsae strains AF16 and HK104. These include 1,363 SNPs that change restriction enzyme recognition sites (snip-SNPs) and 638 indels that range between 7 bp and 2 kb. We established bulk segregant and single animal-based PCR assay conditions and used these to test 107 polymorphisms. A total of 75 polymorphisms, consisting of 14 snip-SNPs and 61 indels, were experimentally confirmed with an overall success rate of 83%. The utility of polymorphisms in genetic studies was demonstrated by successful mapping of 12 mutations, including 5 that were localized to sub-chromosomal regions. Our mapping experiments have also revealed one case of a misassembled contig on chromosome 3. CONCLUSIONS We report a comprehensive set of polymorphisms in C. briggsae wild-type strains and demonstrate their use in mapping mutations. We also show that molecular markers can be useful tools to improve the C. briggsae genome sequence assembly. Our polymorphism resource promises to accelerate genetic and functional studies of C. briggsae genes.
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Affiliation(s)
- Daniel C Koboldt
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Julia Staisch
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | - Karen Haines
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Scott E Baird
- Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA
| | - Helen M Chamberlin
- Department of Molecular Genetics, Ohio State University, Columbus, OH 43210, USA
| | - Eric S Haag
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Raymond D Miller
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Bhagwati P Gupta
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
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8
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Kammenga JE, Phillips PC, De Bono M, Doroszuk A. Beyond induced mutants: using worms to study natural variation in genetic pathways. Trends Genet 2008; 24:178-85. [PMID: 18325626 DOI: 10.1016/j.tig.2008.01.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 01/04/2008] [Accepted: 01/04/2008] [Indexed: 01/30/2023]
Abstract
Induced mutants in the nematode Caenorhabditis elegans are used to study genetic pathways of processes ranging from aging to behavior. The effects of such mutations are usually analyzed in a single wildtype background: N2. However, studies in other species demonstrate that the phenotype(s) of induced mutations can vary widely depending on the genetic background. Moreover, induced mutations in one genetic background do not reveal the allelic effects that segregate in natural populations and contribute to phenotypic variation. Because other wildtype Caenorhabditis spp., including C. elegans, are now available, we review how current mapping resources and methodologies within and between species support the use of Caenorhabditis spp. for studying genetic variation, with a focus on pathways associated with human disease.
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Affiliation(s)
- Jan E Kammenga
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands.
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Zhao Z, Boyle TJ, Bao Z, Murray JI, Mericle B, Waterston RH. Comparative analysis of embryonic cell lineage between Caenorhabditis briggsae and Caenorhabditis elegans. Dev Biol 2008; 314:93-9. [PMID: 18164284 PMCID: PMC2696483 DOI: 10.1016/j.ydbio.2007.11.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 11/08/2007] [Accepted: 11/10/2007] [Indexed: 12/18/2022]
Abstract
Comparative genomic analysis of important signaling pathways in Caenorhabditis briggsae and Caenorhabditis elegans reveals both conserved features and also differences. To build a framework to address the significance of these features we determined the C. briggsae embryonic cell lineage, using the tools StarryNite and AceTree. We traced both cell divisions and cell positions for all cells through all but the last round of cell division and for selected cells through the final round. We found the lineage to be remarkably similar to that of C. elegans. Not only did the founder cells give rise to similar numbers of progeny, the relative cell division timing and positions were largely maintained. These lineage similarities appear to give rise to similar cell fates as judged both by the positions of lineally equivalent cells and by the patterns of cell deaths in both species. However, some reproducible differences were seen, e.g., the P4 cell cycle length is more than 40% longer in C. briggsae than that in C. elegans (p<0.01). The extensive conservation of embryonic development between such divergent species suggests that substantial evolutionary distance between these two species has not altered these early developmental cellular events, although the developmental defects of transpecies hybrids suggest that the details of the underlying molecular pathways have diverged sufficiently so as to not be interchangeable.
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Affiliation(s)
- Zhongying Zhao
- Department of Genome Sciences, Box 355065, University of Washington, 1705 NE Pacific St, Seattle, WA 98195-5065, USA.
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10
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Inoue T, Ailion M, Poon S, Kim HK, Thomas JH, Sternberg PW. Genetic analysis of dauer formation in Caenorhabditis briggsae. Genetics 2007; 177:809-18. [PMID: 17660533 PMCID: PMC2034645 DOI: 10.1534/genetics.107.078857] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molecular changes that underlie evolutionary changes in behavior and physiology are not well understood. Dauer formation in Caenorhabditis elegans is a temperature-sensitive process controlled through a network of signaling pathways associated with sensory neurons and is potentially an excellent system in which to investigate molecular changes in neuronal function during evolution. To begin to investigate the evolution of dauer formation in the genus Caenorhabditis at the molecular level, we isolated dauer-formation mutations in C. briggsae, a species closely related to the model organism C. elegans. We identified mutations in orthologs of C. elegans genes daf-2 (insulin receptor), daf-3 (Smad), and daf-4 (TGF-beta type 2 receptor), as well as genes required for formation of sensory cilia. Phenotypic analyses revealed that functions of these genes are conserved between C. elegans and C. briggsae. Analysis of C. briggsae mutations also revealed a significant difference between the two species in their responses to high temperatures (>26 degrees). C. elegans is strongly induced to form dauers at temperatures above 26 degrees, near the upper limit for growth of C. elegans. In contrast, C. briggsae, which is capable of growth at higher temperatures than C. elegans, lacks this response.
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Affiliation(s)
- Takao Inoue
- HHMI and Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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11
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Zhao Z, Thomas JH, Chen N, Sheps JA, Baillie DL. Comparative genomics and adaptive selection of the ATP-binding-cassette gene family in caenorhabditis species. Genetics 2007; 175:1407-18. [PMID: 17194779 PMCID: PMC1840077 DOI: 10.1534/genetics.106.066720] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 12/24/2006] [Indexed: 11/18/2022] Open
Abstract
ABC transporters constitute one of the largest gene families in all species. They are mostly involved in transport of substrates across membranes. We have previously demonstrated that the Caenorhabditis elegans ABC family shows poor one-to-one gene orthology with other distant model organisms. To address the evolution dynamics of this gene family among closely related species, we carried out a comparative analysis of the ABC family among the three nematode species C. elegans, C. briggsae, and C. remanei. In contrast to the previous observations, the majority of ABC genes in the three species were found in orthologous trios, including many tandemly duplicated ABC genes, indicating that the gene duplication took place before speciation. Species-specific expansions of ABC members are rare and mostly observed in subfamilies A and B. C. briggsae and C. remanei orthologous ABC genes tend to cluster on trees, with those of C. elegans as an outgroup, consistent with their proposed species phylogeny. Comparison of intron/exon structures of the highly conserved ABCE subfamily members also indicates a closer relationship between C. briggsae and C. remanei than between either of these species and C. elegans. A comparison between insect and mammalian species indicates lineage-specific duplications or deletions of ABC genes, while the family size remains relatively constant. Sites undergoing positive selection within subfamily D, which are implicated in very-long-chain fatty acid transport, were identified. The evolution of these sites might be driven by the changes in food source with time.
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Affiliation(s)
- Zhongying Zhao
- British Columbia Cancer Research Center, Vancouver, British Columbia V5Z 1L6, Canada.
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12
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Konwerski J, Senchuk M, Petty E, Lahaie D, Schisa JA. Cloning and expression analysis ofpos-1 in the nematodesCaenorhabditis briggsae andCaenorhabditis remanei. Dev Dyn 2005; 233:1006-12. [PMID: 15880508 DOI: 10.1002/dvdy.20421] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The Caenorhabditis elegans pos-1 gene encodes a zinc-finger protein that is required for germline specification during embryogenesis. The maternally provided mRNA is translationally regulated both spatially and temporally during early development. We have cloned orthologs of pos-1 from C. briggsae and C. remanei, two Caenorhabditis species that have diverged from C. elegans by approximately 20-40 million years. Two regions in the 3' untranslated region are highly conserved among all three species. We find that the pos-1 RNA is expressed in the hermaphrodite and female gonads of C. briggsae and C. remanei but POS-1 protein is not detected at high levels in C. briggsae until the 2-cell stage of embryogenesis. The protein expression is restricted to the germline precursors of the embryo. We conclude that pos-1 appears to be translationally regulated in C. briggsae as it is in C. elegans and speculate the conserved 3' UTR sequences may be involved.
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Affiliation(s)
- Jamie Konwerski
- Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859, USA
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Gutierrez A, Sommer RJ. Evolution of dnmt-2 and mbd-2-like genes in the free-living nematodes Pristionchus pacificus, Caenorhabditis elegans and Caenorhabditis briggsae. Nucleic Acids Res 2004; 32:6388-96. [PMID: 15576683 PMCID: PMC535690 DOI: 10.1093/nar/gkh982] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Whole genome sequencing of several metazoan model organisms provides a platform for studying genome evolution. How representative are the genomes of these model organisms for their respective phyla? Within nematodes, for example, the free-living soil nematode Caenorhabditis elegans is a highly derived species with unusual genomic characters, such as a reduced Hox cluster (Curr. Biol., 13, 37-40) and the absence of a Hedgehog signaling system. Here, we describe the recent loss of a DNA methyltransferase-2 gene (dnmt-2) in C.elegans. A dnmt-2-like gene is present in the satellite model organism Pristionchus pacificus, another free-living nematode that diverged from C.elegans 200-300 million years ago. In contrast, C.elegans, Caenorhabditis briggsae and P.pacificus all contain an mbd-2-like gene, which encodes another essential component of the methylation system of higher animals and fungi. Cel-mbd-2 is expressed throughout development and RNA interference (RNAi) experiments result in variable phenotypes. In contrast, Cbr-mbd-2 RNAi results in paralyzed larval or adult worms suggesting recent changes of gene function within the genus Caenorhabditis. We speculate that both genes were part of an ancestral DNA methylation system in nematodes and that gene loss and sequence divergence have abolished DNA methylation in C.elegans.
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Affiliation(s)
- Arturo Gutierrez
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Evolutionsbiologie, Spemannstrasse 37-39, D-72076 Tübingen, Germany
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Kiontke K, Gavin NP, Raynes Y, Roehrig C, Piano F, Fitch DHA. Caenorhabditis phylogeny predicts convergence of hermaphroditism and extensive intron loss. Proc Natl Acad Sci U S A 2004; 101:9003-8. [PMID: 15184656 PMCID: PMC428462 DOI: 10.1073/pnas.0403094101] [Citation(s) in RCA: 265] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Indexed: 11/18/2022] Open
Abstract
Despite the prominence of Caenorhabditis elegans as a major developmental and genetic model system, its phylogenetic relationship to its closest relatives has not been resolved. Resolution of these relationships is necessary for studying the steps that underlie life history, genomic, and morphological evolution of this important system. By using data from five different nuclear genes from 10 Caenorhabditis species currently in culture, we find a well resolved phylogeny that reveals three striking patterns in the evolution of this animal group: (i) Hermaphroditism has evolved independently in C. elegans and its close relative Caenorhabditis briggsae; (ii) there is a large degree of intron turnover within Caenorhabditis, and intron losses are much more frequent than intron gains; and (iii) despite the lack of marked morphological diversity, more genetic disparity is present within this one genus than has occurred within all vertebrates.
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Affiliation(s)
- Karin Kiontke
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
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Abstract
Over the past two to three decades, developmental biology has demonstrated that all multicellular organisms in the animal kingdom share many of the same molecular building blocks and many of the same regulatory genetic pathways. Yet we still do not understand how the various organisms use these molecules and pathways to assume all the forms we know today. Evolutionary developmental biology tackles this problem by comparing the development of one organism to another and comparing the genes involved and gene functions to understand what makes one organism different from another. In this review, we revisit a set of seven concepts defined by Lewis Wolpert (fate maps, asymmetric division, induction, competence, positional information, determination, and lateral inhibition) that describe the characters of many developmental systems and supplement them with three additional concepts (developmental genomics, genetic redundancy, and genetic networks). We will discuss examples of comparative developmental studies where these concepts have guided observations on the advent of a developmental novelty. Finally, we identify a set of evolutionary frameworks, such as developmental constraints, cooption, duplication, parallel and convergent evolution, and homoplasy, to adequately describe the evolutionary properties of developmental systems.
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Affiliation(s)
- David Rudel
- Max-Planck Institut für Entwicklungsbiologie, Abteilung Evolutionsbiologie, Spemannstrasse 37-39, D-72076 Tübingen, Germany
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