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Sun S, Kanzaki N, Dayi M, Maeda Y, Yoshida A, Tanaka R, Kikuchi T. The compact genome of Caenorhabditis niphades n. sp., isolated from a wood-boring weevil, Niphades variegatus. BMC Genomics 2022; 23:765. [PMID: 36418933 PMCID: PMC9682657 DOI: 10.1186/s12864-022-09011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The first metazoan genome sequenced, that of Caenorhabditis elegans, has motivated animal genome evolution studies. To date > 50 species from the genus Caenorhabditis have been sequenced, allowing research on genome variation. RESULTS In the present study, we describe a new gonochoristic species, Caenorhabditis niphades n. sp., previously referred as C. sp. 36, isolated from adult weevils (Niphades variegatus), with whom they appear to be tightly associated during its life cycle. Along with a species description, we sequenced the genome of C. niphades n. sp. and produced a chromosome-level assembly. A genome comparison highlighted that C. niphades n. sp. has the smallest genome (59 Mbp) so far sequenced in the Elegans supergroup, despite being closely related to a species with an exceptionally large genome, C. japonica. CONCLUSIONS The compact genome of C. niphades n. sp. can serve as a key resource for comparative evolutionary studies of genome and gene number expansions in Caenorhabditis species.
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Affiliation(s)
- Simo Sun
- grid.26999.3d0000 0001 2151 536XDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan ,grid.410849.00000 0001 0657 3887Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Miyazaki, 889-1692 Japan
| | - Natsumi Kanzaki
- grid.417935.d0000 0000 9150 188XKansai Research Center, Forestry and Forest Products Research Institute, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto, 612-0855 Japan
| | - Mehmet Dayi
- grid.26999.3d0000 0001 2151 536XDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan ,grid.412121.50000 0001 1710 3792Forestry Vocational School, Duzce University, 81620 Duzce, Türkiye
| | - Yasunobu Maeda
- grid.26999.3d0000 0001 2151 536XDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan ,grid.410849.00000 0001 0657 3887Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Miyazaki, 889-1692 Japan
| | - Akemi Yoshida
- grid.410849.00000 0001 0657 3887Genomics and Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, Miyazaki, 889-1692 Japan
| | - Ryusei Tanaka
- grid.410849.00000 0001 0657 3887Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Miyazaki, 889-1692 Japan
| | - Taisei Kikuchi
- grid.26999.3d0000 0001 2151 536XDepartment of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan ,grid.410849.00000 0001 0657 3887Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Miyazaki, 889-1692 Japan
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Diano MA, Dalan L, Singh PR, Sumaya NH. First report, morphological and molecular characterization of Caenorhabditis brenneri (Nematoda: Rhabditidae) isolated from the giant African land snail Achatina fulica (Gastropoda: Achatinidae). Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-021-00972-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Adams PE, Crist AB, Young EM, Willis JH, Phillips PC, Fierst JL. Slow Recovery from Inbreeding Depression Generated by the Complex Genetic Architecture of Segregating Deleterious Mutations. Mol Biol Evol 2022; 39:msab330. [PMID: 34791426 PMCID: PMC8789292 DOI: 10.1093/molbev/msab330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The deleterious effects of inbreeding have been of extreme importance to evolutionary biology, but it has been difficult to characterize the complex interactions between genetic constraints and selection that lead to fitness loss and recovery after inbreeding. Haploid organisms and selfing organisms like the nematode Caenorhabditis elegans are capable of rapid recovery from the fixation of novel deleterious mutation; however, the potential for recovery and genomic consequences of inbreeding in diploid, outcrossing organisms are not well understood. We sought to answer two questions: 1) Can a diploid, outcrossing population recover from inbreeding via standing genetic variation and new mutation? and 2) How does allelic diversity change during recovery? We inbred C. remanei, an outcrossing relative of C. elegans, through brother-sister mating for 30 generations followed by recovery at large population size. Inbreeding reduced fitness but, surprisingly, recovery from inbreeding at large populations sizes generated only very moderate fitness recovery after 300 generations. We found that 65% of ancestral single nucleotide polymorphisms (SNPs) were fixed in the inbred population, far fewer than the theoretical expectation of ∼99%. Under recovery, 36 SNPs across 30 genes involved in alimentary, muscular, nervous, and reproductive systems changed reproducibly across replicates, indicating that strong selection for fitness recovery does exist. Our results indicate that recovery from inbreeding depression via standing genetic variation and mutation is likely to be constrained by the large number of segregating deleterious variants present in natural populations, limiting the capacity for recovery of small populations.
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Affiliation(s)
- Paula E Adams
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | - Anna B Crist
- Department of Genomes and Genetics, Institut Pasteur, Paris, France
| | - Ellen M Young
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - John H Willis
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, USA
| | - Janna L Fierst
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
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Abstract
Wild populations of the model organism C. elegans represent a valuable resource, allowing for genetic characterization underlying natural phenotypic variation. Here we provide a simple protocol on how to sample and rapidly identify C. elegans wild isolates. We outline how to find suitable habitats and organic substrates, followed by describing isolation and identification of C. elegans live cultures based on easily recognizable morphological characteristics, molecular barcodes, and mating tests. This protocol uses standard laboratory equipment and requires little prior knowledge of C. elegans biology.
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Affiliation(s)
| | - Nausicaa Poullet
- Université Côte d'Azur, CNRS, Inserm, IBV, Nice, France
- URZ, INRAE, Petit-Bourg (Guadeloupe), France
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Britz S, Markert SM, Witvliet D, Steyer AM, Tröger S, Mulcahy B, Kollmannsberger P, Schwab Y, Zhen M, Stigloher C. Structural Analysis of the Caenorhabditis elegans Dauer Larval Anterior Sensilla by Focused Ion Beam-Scanning Electron Microscopy. Front Neuroanat 2021; 15:732520. [PMID: 34819841 PMCID: PMC8607169 DOI: 10.3389/fnana.2021.732520] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/24/2021] [Indexed: 11/13/2022] Open
Abstract
At the end of the first larval stage, the nematode Caenorhabditis elegans developing in harsh environmental conditions is able to choose an alternative developmental path called the dauer diapause. Dauer larvae exhibit different physiology and behaviors from non-dauer larvae. Using focused ion beam-scanning electron microscopy (FIB-SEM), we volumetrically reconstructed the anterior sensory apparatus of C. elegans dauer larvae with unprecedented precision. We provide a detailed description of some neurons, focusing on structural details that were unknown or unresolved by previously published studies. They include the following: (1) dauer-specific branches of the IL2 sensory neurons project into the periphery of anterior sensilla and motor or putative sensory neurons at the sub-lateral cords; (2) ciliated endings of URX sensory neurons are supported by both ILso and AMso socket cells near the amphid openings; (3) variability in amphid sensory dendrites among dauers; and (4) somatic RIP interneurons maintain their projection into the pharyngeal nervous system. Our results support the notion that dauer larvae structurally expand their sensory system to facilitate searching for more favorable environments.
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Affiliation(s)
- Sebastian Britz
- Imaging Core Facility of the Biocenter, Theodor-Boveri-Institute, Julius-Maximilians-University, Würzburg, Germany
| | - Sebastian Matthias Markert
- Imaging Core Facility of the Biocenter, Theodor-Boveri-Institute, Julius-Maximilians-University, Würzburg, Germany
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
- Department of Molecular Genetics, Physiology and Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Anna Maria Steyer
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Sarah Tröger
- Imaging Core Facility of the Biocenter, Theodor-Boveri-Institute, Julius-Maximilians-University, Würzburg, Germany
| | - Ben Mulcahy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
- Department of Molecular Genetics, Physiology and Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-University, Würzburg, Germany
| | - Yannick Schwab
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada
- Department of Molecular Genetics, Physiology and Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Christian Stigloher
- Imaging Core Facility of the Biocenter, Theodor-Boveri-Institute, Julius-Maximilians-University, Würzburg, Germany
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Worm-Based Microfluidic Biosensor for Real-Time Assessment of the Metastatic Status. Cancers (Basel) 2021; 13:cancers13040873. [PMID: 33669617 PMCID: PMC7922733 DOI: 10.3390/cancers13040873] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 01/18/2023] Open
Abstract
Simple Summary We proposed a high-throughput screening and low-cost worm-based (WB) microfluidic biosensor to monitor biochemical cues related to metastasis. Caenorhabditis elegans placed in the WB biosensor chambers and exposed to samples conditioned with cancer cell clusters reflect differences in the chemotactic preference of worms. We observed a higher distribution of worms associated with samples of higher metastatic potential (p < 0.005). A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where increased metastatic potential was associated with higher CI levels (6.5 ± 1.37). We found that the secreted metabolite glutamate was a chemorepellent, and lower glutamate levels were associated with samples derived from more metastatic cancer cell clusters. In conclusion, WB biosensors could evaluate patient status in real time, thereby facilitating early detection of metastases and routine management. Abstract Background: Metastasis is a complex process that affects patient treatment and survival. To routinely monitor cancer plasticity and guide treatment strategies, it is highly desired to provide information about metastatic status in real-time. Here, we proposed a worm-based (WB) microfluidic biosensor to rapidly monitor biochemical cues related to metastasis in a well-defined environment. Compared to conventional biomarker-based methods, the WB biosensor allowed high throughput screening under low cost, requiring only visual quantification of outputs; Methods: Caenorhabditis elegans were placed in the WB biosensor and exposed to samples conditioned with cancer cell clusters. The chemotactic preference of these worms was observed under discontinuous imaging to minimize the impact on physiological activity; Results: A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where moderate (3.24–6.5) and high (>6.5) CI levels reflected increased metastasis risk and presence of metastasis, respectively. We demonstrated that the secreted metabolite glutamate was a chemorepellent, and larger clusters associated with increased metastatic potential also enhanced CI levels; Conclusions: Overall, this study provided a proof of concept for the WB biosensors in assessing metastasis status, with the potential to evaluate patient-derived cancer clusters for routine management.
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Stevens L, Rooke S, Falzon LC, Machuka EM, Momanyi K, Murungi MK, Njoroge SM, Odinga CO, Ogendo A, Ogola J, Fèvre EM, Blaxter M. The Genome of Caenorhabditis bovis. Curr Biol 2020; 30:1023-1031.e4. [PMID: 32109387 DOI: 10.1016/j.cub.2020.01.074] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/10/2019] [Accepted: 01/23/2020] [Indexed: 11/26/2022]
Abstract
The free-living nematode Caenorhabditis elegans is a key laboratory model for metazoan biology. C. elegans has also become a model for parasitic nematodes despite being only distantly related to most parasitic species. All of the ∼65 Caenorhabditis species currently in culture are free-living, with most having been isolated from decaying plant or fungal matter. Caenorhabditis bovis is a particularly unusual species that has been isolated several times from the inflamed ears of Zebu cattle in Eastern Africa, where it is associated with the disease bovine parasitic otitis. C. bovis is therefore of particular interest to researchers interested in the evolution of nematode parasitism. However, as C. bovis is not in laboratory culture, it remains little studied. Here, by sampling livestock markets and slaughterhouses in Western Kenya, we successfully reisolated C. bovis from the ear of adult female Zebu. We sequenced the genome of C. bovis using the Oxford Nanopore MinION platform in a nearby field laboratory and used the data to generate a chromosome-scale draft genome sequence. We exploited this draft genome sequence to reconstruct the phylogenetic relationships of C. bovis to other Caenorhabditis species and reveal the changes in genome size and content that have occurred during its evolution. We also identified expansions in several gene families that have been implicated in parasitism in other nematode species. The high-quality draft genome and our analyses thereof represent a significant advancement in our understanding of this unusual Caenorhabditis species.
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Affiliation(s)
- Lewis Stevens
- Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK.
| | - Stefan Rooke
- Usher Institute, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Laura C Falzon
- Institute of Infection and Global Health, University of Liverpool, 8 West Derby Street, Liverpool L69 7BE, UK; International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Eunice M Machuka
- Biosciences, Eastern and Central Africa, International Livestock Research Institute (BecA-ILRI) Hub, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Kelvin Momanyi
- International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Maurice K Murungi
- International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Samuel M Njoroge
- International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya; Centre for Microbiology Research, Kenya Medical Research Institute, KNH Grounds, PO Box 54840 00200, Nairobi, Kenya
| | - Christian O Odinga
- International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Allan Ogendo
- Veterinary Department, Busia County Government, PO Box Private Bag 50400, Busia, Kenya
| | - Joseph Ogola
- Veterinary Department, Bungoma County Government, PO Box 2489 50200, Bungoma, Kenya
| | - Eric M Fèvre
- Institute of Infection and Global Health, University of Liverpool, 8 West Derby Street, Liverpool L69 7BE, UK; International Livestock Research Institute, Old Naivasha Road, PO Box 30709 00100, Nairobi, Kenya
| | - Mark Blaxter
- Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK
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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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Guerrero R, Rincon-Orozco B, Delgado NU. Achatina fulica (Mollusca: Achatinidae) Naturally Infected with Caenorhabditis briggsae (Dougherty and Nigon, 1949) (Nematoda: Rhabditidae). J Parasitol 2018; 104:679-684. [PMID: 30240329 DOI: 10.1645/15-807] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Specimens of the African snail Achatina fulica, collected in Bucaramanga, Colombia, were examined for parasites. Numerous specimens of Caenorhabditis briggsae were collected from the digestive tract of the snails and identified by the structure of male spiculum, caudal bursa, gubernaculum and precloacal lip in males, triangular tooth in metarhabdion, and protandrous hermaphrodites with a female:male ratio of 15:1 and with morphometry. DNA sequences of the ITS2 region of the ribosomal gene array from worms in this study matched with 99% similarity to published sequences of C. briggsae. A redescription of the species is provided. This is the first record of the species in South America.
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Affiliation(s)
- Ricardo Guerrero
- 1 Laboratorio de Biología de Vectores y Parásitos, Centro de Ecología y Evolución, Facultad de Ciencias, Universidad Central de Venezuela, P.O. Box 47058, Caracas 1041ª, Venezuela
| | - Bladimiro Rincon-Orozco
- 2 Escuela de Microbiología, Universidad Industrial de Santander, P.O. Box 680006, Bucaramanga, Colombia
| | - Nelson Uribe Delgado
- 2 Escuela de Microbiología, Universidad Industrial de Santander, P.O. Box 680006, Bucaramanga, Colombia
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10
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Yin D, Schwarz EM, Thomas CG, Felde RL, Korf IF, Cutter AD, Schartner CM, Ralston EJ, Meyer BJ, Haag ES. Rapid genome shrinkage in a self-fertile nematode reveals sperm competition proteins. Science 2018; 359:55-61. [PMID: 29302007 PMCID: PMC5789457 DOI: 10.1126/science.aao0827] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/17/2017] [Indexed: 12/30/2022]
Abstract
To reveal impacts of sexual mode on genome content, we compared chromosome-scale assemblies of the outcrossing nematode Caenorhabditis nigoni to its self-fertile sibling species, C. briggsaeC. nigoni's genome resembles that of outcrossing relatives but encodes 31% more protein-coding genes than C. briggsaeC. nigoni genes lacking C. briggsae orthologs were disproportionately small and male-biased in expression. These include the male secreted short (mss) gene family, which encodes sperm surface glycoproteins conserved only in outcrossing species. Sperm from mss-null males of outcrossing C. remanei failed to compete with wild-type sperm, despite normal fertility in noncompetitive mating. Restoring mss to C. briggsae males was sufficient to enhance sperm competitiveness. Thus, sex has a pervasive influence on genome content that can be used to identify sperm competition factors.
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Affiliation(s)
- Da Yin
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Erich M Schwarz
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
| | - Cristel G Thomas
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Rebecca L Felde
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ian F Korf
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA 95616, USA
| | - Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
| | - Caitlin M Schartner
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Edward J Ralston
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Barbara J Meyer
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Eric S Haag
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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11
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Slos D, Sudhaus W, Stevens L, Bert W, Blaxter M. Caenorhabditis monodelphis sp. n.: defining the stem morphology and genomics of the genus Caenorhabditis. BMC ZOOL 2017. [DOI: 10.1186/s40850-017-0013-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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12
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Abstract
Wild populations of the model organism C. elegans allow characterization of natural genetic variation underlying diverse phenotypic traits. Here we provide a simple protocol on how to sample and rapidly identify C. elegans wild isolates. We outline how to find suitable habitats and organic substrates, followed by describing isolation and identification of C. elegans live cultures based on easily recognizable morphological characteristics, molecular barcodes and/or mating tests. This protocol uses standard laboratory equipment and requires no prior knowledge of C. elegans biology.
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Affiliation(s)
- Nausicaa Poullet
- Institut de Biologie Valrose, CNRS UMR7277, Parc Valrose, Nice, Cedex 02, 06108, France.,INSERM U1091, Nice, Cedex 02, 06108, France.,Université Nice Sophia Antipolis, UFR Sciences, Nice, Cedex 02, 06108, France
| | - Christian Braendle
- Institut de Biologie Valrose, CNRS UMR7277, Parc Valrose, Nice, Cedex 02, 06108, France. .,INSERM U1091, Nice, Cedex 02, 06108, France. .,Université Nice Sophia Antipolis, UFR Sciences, Nice, Cedex 02, 06108, France.
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13
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Jay Burr AH, Baldwin JG. The nematode stoma: Homology of cell architecture with improved understanding by confocal microscopy of labeled cell boundaries. J Morphol 2016; 277:1168-86. [DOI: 10.1002/jmor.20567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/24/2016] [Accepted: 05/26/2016] [Indexed: 11/08/2022]
Affiliation(s)
- A. H. Jay Burr
- Department of Biological Sciences; Simon Fraser University; Burnaby British Columbia V5A 1S6 Canada
- Department of Nematology; University of California; Riverside California 92521
| | - James G. Baldwin
- Department of Nematology; University of California; Riverside California 92521
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14
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Molecular identification and phylogenetic analysis of Metarhabditis blumi (Nematoda: Rhabditida). Vet Parasitol 2015; 214:184-6. [DOI: 10.1016/j.vetpar.2015.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 06/07/2015] [Accepted: 06/13/2015] [Indexed: 11/20/2022]
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Abstract
The roundworm Caenorhabditis elegans has risen to the status of a top model organism for biological research in the last fifty years. Among laboratory animals, this tiny nematode is one of the simplest and easiest organisms to handle. And its life outside the laboratory is beginning to be unveiled. Like other model organisms, C. elegans has a boom-and-bust lifestyle. It feasts on ephemeral bacterial blooms in decomposing fruits and stems. After resource depletion, its young larvae enter a migratory diapause stage, called the dauer. Organisms known to be associated with C. elegans include migration vectors (such as snails, slugs and isopods) and pathogens (such as microsporidia, fungi, bacteria and viruses). By deepening our understanding of the natural history of C. elegans, we establish a broader context and improved tools for studying its biology.
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Affiliation(s)
- Lise Frézal
- Institute of Biology of Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Paris, France
| | - Marie-Anne Félix
- Institute of Biology of Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Paris, France
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16
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Félix MA, Braendle C, Cutter AD. A streamlined system for species diagnosis in Caenorhabditis (Nematoda: Rhabditidae) with name designations for 15 distinct biological species. PLoS One 2014; 9:e94723. [PMID: 24727800 PMCID: PMC3984244 DOI: 10.1371/journal.pone.0094723] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/14/2014] [Indexed: 12/18/2022] Open
Abstract
The rapid pace of species discovery outstrips the rate of species description in many taxa. This problem is especially acute for Caenorhabditis nematodes, where the naming of distinct species would greatly improve their visibility and usage for biological research, given the thousands of scientists studying Caenorhabditis. Species description and naming has been hampered in Caenorhabditis, in part due to the presence of morphologically cryptic species despite complete biological reproductive isolation and often enormous molecular divergence. With the aim of expediting species designations, here we propose and apply a revised framework for species diagnosis and description in this group. Our solution prioritizes reproductive isolation over traditional morphological characters as the key feature in delineating and diagnosing new species, reflecting both practical considerations and conceptual justifications. DNA sequence divergence criteria help prioritize crosses for establishing patterns of reproductive isolation among the many species of Caenorhabditis known to science, such as with the ribosomal internal transcribed spacer-2 (ITS2) DNA barcode. By adopting this approach, we provide new species name designations for 15 distinct biological species, thus increasing the number of named Caenorhabditis species in laboratory culture by nearly 3-fold. We anticipate that the improved accessibility of these species to the research community will expand the opportunities for study and accelerate our understanding of diverse biological phenomena.
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Affiliation(s)
- Marie-Anne Félix
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Paris, France
- CNRS UMR 8197, Paris, France
- Inserm U1024, Paris, France
| | - Christian Braendle
- Institut de Biologie Valrose, CNRS UMR7277, Parc Valrose, Nice, France
- INSERM U1091, Nice, France
- Université Nice Sophia Antipolis, UFR Sciences, Nice, France
| | - Asher D. Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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17
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Baird SE, Seibert SR. Reproductive isolation in the Elegans-Group of Caenorhabditis. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ns.2013.54a004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Zou M, Wang G, He S. Evolutionary patterns of RNA-based gene duplicates in Caenorhabditis nematodes coincide with their genomic features. BMC Res Notes 2012; 5:398. [PMID: 22853807 PMCID: PMC3532220 DOI: 10.1186/1756-0500-5-398] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 07/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND RNA-based gene duplicates (retrocopies) played pivotal roles in many physiological processes. Nowadays, functional retrocopies have been systematically identified in several mammals, fruit flies, plants, zebrafish and other chordates, etc. However, studies about this kind of duplication in Caenorhabditis nematodes have not been reported. FINDINGS We identified 43, 48, 43, 9, and 42 retrocopies, of which 6, 15, 18, 3, and 13 formed chimeric genes in C. brenneri, C. briggsae, C. elegans, C. japonica, and C. remanei, respectively. At least 5 chimeric types exist in Caenorhabditis species, of which retrocopy recruiting both N and C terminus is the commonest one. Evidences from different analyses demonstrate many retrocopies and almost all chimeric genes may be functional in these species. About half of retrocopies in each species has coordinates in other species, and we suggest that retrocopies in closely related species may be helpful in identifying retrocopies for one certain species. CONCLUSIONS A number of retrocopies and chimeric genes exist in Caenorhabditis genomes, and some of them may be functional. The evolutionary patterns of these genes may correlate with their genomic features, such as the activity of retroelements, the high rate of mutation and deletion rate, and a large proportion of genes subject to trans-splicing.
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Affiliation(s)
- Ming Zou
- The key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China
- University of the Chinese Academy of Sciences, Beijing 100039, PR China
| | - Guoxiu Wang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, HuaZhong Normal University, Wuhan, Hubei, China
| | - Shunping He
- The key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China
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Global population genetic structure of Caenorhabditis remanei reveals incipient speciation. Genetics 2012; 191:1257-69. [PMID: 22649079 DOI: 10.1534/genetics.112.140418] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mating system transitions dramatically alter the evolutionary trajectories of genomes that can be revealed by contrasts of species with disparate modes of reproduction. For such transitions in Caenorhabditis nematodes, some major causes of genome variation in selfing species have been discerned. And yet, we have only limited understanding of species-wide population genetic processes for their outcrossing relatives, which represent the reproductive state of the progenitors of selfing species. Multilocus-multipopulation sequence polymorphism data provide a powerful means to uncover the historical demography and evolutionary processes that shape genomes. Here we survey nucleotide polymorphism across the X chromosome for three populations of the outcrossing nematode Caenorhabditis remanei and demonstrate its divergence from a fourth population describing a closely related new species from China, C. sp. 23. We find high genetic variation globally and within each local population sample. Despite geographic barriers and moderate genetic differentiation between Europe and North America, considerable gene flow connects C. remanei populations. We discovered C. sp. 23 while investigating C. remanei, observing strong genetic differentiation characteristic of reproductive isolation that was confirmed by substantial F2 hybrid breakdown in interspecific crosses. That C. sp. 23 represents a distinct biological species provides a cautionary example of how standard practice can fail for mating tests of species identity in this group. This species pair permits full application of divergence population genetic methods to obligately outcrossing species of Caenorhabditis and also presents a new focus for interrogation of the genetics and evolution of speciation with the Caenorhabditis model system.
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20
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Baldi C, Viviano J, Ellis RE. A bias caused by ectopic development produces sexually dimorphic sperm in nematodes. Curr Biol 2011; 21:1416-20. [PMID: 21835620 DOI: 10.1016/j.cub.2011.07.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 06/07/2011] [Accepted: 07/21/2011] [Indexed: 10/17/2022]
Abstract
Self-fertile hermaphrodites have evolved independently several times in the genus Caenorhabditis [1, 2]. These XX hermaphrodites make smaller sperm than males [3, 4], which they use to fertilize their own oocytes. Because larger sperm outcompete smaller sperm in nematodes [3-5], it had been assumed that this dimorphism evolved in response to sperm competition. However, we show that it was instead caused by a developmental bias. When we transformed females of the species Caenorhabditis remanei into hermaphrodites [6], their sperm were significantly smaller than those of males. Because this species never makes hermaphrodites in the wild, this dimorphism cannot be due to selection. Instead, analyses of the related nematode Caenorhabditis elegans suggest that this dimorphism might reflect the development of sperm within the distinct physiological environment of the hermaphrodite gonad. These results reveal a new mechanism for some types of developmental bias-the effects of a novel physical location alter the development of ectopic cells in predictable ways.
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Affiliation(s)
- Christopher Baldi
- Graduate School of Biomedical Sciences, The UMDNJ School of Osteopathic Medicine, B303 Science Center, 2 Medical Center Drive, Stratford, NJ 08084, USA
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21
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Affiliation(s)
- Mark Blaxter
- Institute of Evolutionary Biology, The University of Edinburgh, Ashworth Laboratories, Edinburgh, United Kingdom.
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22
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Velonà A, Luchetti A, Scanabissi F, Mantovani B. Genetic variability and reproductive modalities in European populations ofTriops cancriformis(Crustacea, Branchiopoda, Notostraca). ACTA ACUST UNITED AC 2009. [DOI: 10.1080/11250000902785314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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23
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Carta LK, Handoo ZA, Hoberg EP, Erbe EF, Wergin WP. Evaluation of Some Vulval Appendages in Nematode Taxonomy. COMP PARASITOL 2009. [DOI: 10.1654/4302.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Kuntz SG, Schwarz EM, DeModena JA, De Buysscher T, Trout D, Shizuya H, Sternberg PW, Wold BJ. Multigenome DNA sequence conservation identifies Hox cis-regulatory elements. Genome Res 2008; 18:1955-68. [PMID: 18981268 DOI: 10.1101/gr.085472.108] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To learn how well ungapped sequence comparisons of multiple species can predict cis-regulatory elements in Caenorhabditis elegans, we made such predictions across the large, complex ceh-13/lin-39 locus and tested them transgenically. We also examined how prediction quality varied with different genomes and parameters in our comparisons. Specifically, we sequenced approximately 0.5% of the C. brenneri and C. sp. 3 PS1010 genomes, and compared five Caenorhabditis genomes (C. elegans, C. briggsae, C. brenneri, C. remanei, and C. sp. 3 PS1010) to find regulatory elements in 22.8 kb of noncoding sequence from the ceh-13/lin-39 Hox subcluster. We developed the MUSSA program to find ungapped DNA sequences with N-way transitive conservation, applied it to the ceh-13/lin-39 locus, and transgenically assayed 21 regions with both high and low degrees of conservation. This identified 10 functional regulatory elements whose activities matched known ceh-13/lin-39 expression, with 100% specificity and a 77% recovery rate. One element was so well conserved that a similar mouse Hox cluster sequence recapitulated the native nematode expression pattern when tested in worms. Our findings suggest that ungapped sequence comparisons can predict regulatory elements genome-wide.
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Affiliation(s)
- Steven G Kuntz
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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25
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Lockery SR, Lawton KJ, Doll JC, Faumont S, Coulthard SM, Thiele TR, Chronis N, McCormick KE, Goodman MB, Pruitt BL. Artificial dirt: microfluidic substrates for nematode neurobiology and behavior. J Neurophysiol 2008; 99:3136-43. [PMID: 18337372 DOI: 10.1152/jn.91327.2007] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With a nervous system of only 302 neurons, the free-living nematode Caenorhabditis elegans is a powerful experimental organism for neurobiology. However, the laboratory substrate commonly used in C. elegans research, a planar agarose surface, fails to reflect the complexity of this organism's natural environment, complicates stimulus delivery, and is incompatible with high-resolution optophysiology experiments. Here we present a new class of microfluidic devices for C. elegans neurobiology and behavior: agarose-free, micron-scale chambers and channels that allow the animals to crawl as they would on agarose. One such device mimics a moist soil matrix and facilitates rapid delivery of fluid-borne stimuli. A second device consists of sinusoidal channels that can be used to regulate the waveform and trajectory of crawling worms. Both devices are thin and transparent, rendering them compatible with high-resolution microscope objectives for neuronal imaging and optical recording. Together, the new devices are likely to accelerate studies of the neuronal basis of behavior in C. elegans.
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Affiliation(s)
- S R Lockery
- Department of Biology, University of Oregon, Eugene, Oregon 97403-1210, USA.
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26
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Félix MA. Cryptic quantitative evolution of the vulva intercellular signaling network in Caenorhabditis. Curr Biol 2007; 17:103-14. [PMID: 17240335 DOI: 10.1016/j.cub.2006.12.024] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 11/22/2006] [Accepted: 11/23/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND The Caenorhabditis vulva is formed from a row of Pn.p precursor cells, which adopt a spatial cell-fate pattern-3 degrees 3 degrees 2 degrees 1 degrees 2 degrees 3 degrees -centered on the gonadal anchor cell. This pattern is robustly specified by an intercellular signaling network including EGF/Ras induction from the anchor cell and Delta/Notch signaling between the precursor cells. It is unknown how the roles and quantitative contributions of these signaling pathways have evolved in closely related Caenorhabditis species. RESULTS Cryptic evolution in the network is uncovered by quantification of cell-fate-pattern frequencies obtained after displacement of the system out of its normal range, either by anchor-cell ablations or through LIN-3/EGF overexpression. Silent evolution in the Caenorhabditis genus covers a large neutral space of cell-fate patterns. Direct induction of the 1 degrees fate as in C. elegans appeared within the genus. C. briggsae displays a graded induction of 1 degrees and 2 degrees fates, with 1 degrees fate induction requiring a longer time than in C. elegans, and a reduced lateral inhibition of adjacent 1 degrees fates. C. remanei displays a strong lateral induction of 2 degrees fates relative to vulval-fate activation in the central cell. This evolution in cell-fate pattern space can be experimentally reconstituted by mild variations of Ras, Wnt, and Notch pathway activities in C. elegans and C. briggsae. CONCLUSIONS Quantitative evolution in the roles of graded induction by LIN-3/EGF and Notch signaling is demonstrated for the Caenorhabditis vulva signaling network. This evolutionary system biology approach provides a quantitative view of the variational properties of this biological system.
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Affiliation(s)
- Marie-Anne Félix
- Institut Jacques Monod, Centre National de la Recherche Scientifique, Universities of Paris 6 and 7, Tour 43, 2 place Jussieu , 75251 Paris cedex 05, France.
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27
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Mackiewicz M, Tatarenkov A, Taylor DS, Turner BJ, Avise JC. Extensive outcrossing and androdioecy in a vertebrate species that otherwise reproduces as a self-fertilizing hermaphrodite. Proc Natl Acad Sci U S A 2006; 103:9924-8. [PMID: 16785430 PMCID: PMC1502555 DOI: 10.1073/pnas.0603847103] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mangrove killifish (Kryptolebias marmoratus) is the only vertebrate known to be capable of self-fertilization. Its gonad is typically an ovotestis that simultaneously produces eggs and sperm, and fertilization is internal. Although most populations of this species consist primarily or exclusively of hermaphroditic individuals, gonochoristic males occur at approximately 20% frequency in a natural population at Twin Cays, Belize. Here we use a battery of 36 microsatellite loci to document a striking genetic pattern (high intraspecimen heterozygosities and low within-population linkage disequilibria) that differs qualitatively from the highly homozygous (or "clonal") genetic architecture characteristic of killifish populations previously studied in Florida, where males are much rarer. These findings document that outcrossing (probably between gonochoristic males and hermaphrodites) is common at the Belize site, and, more importantly, they demonstrate the dramatic impact that functional androdioecy can have on the population genetic architecture of this reproductively unique vertebrate species.
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Affiliation(s)
- Mark Mackiewicz
- *Department of Genetics, University of Georgia, Athens, GA 30602
| | - Andrey Tatarenkov
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
| | - D. Scott Taylor
- Brevard County Environmentally Endangered Lands Program, Melbourne, FL 32940; and
| | - Bruce J. Turner
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - John C. Avise
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
- To whom correspondence should be addressed. E-mail:
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Geldziler B, Chatterjee I, Kadandale P, Putiri E, Patel R, Singson A. A comparative study of sperm morphology, cytology and activation in Caenorhabditis elegans, Caenorhabditis remanei and Caenorhabditis briggsae. Dev Genes Evol 2006; 216:198-208. [PMID: 16389557 DOI: 10.1007/s00427-005-0045-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 11/21/2005] [Indexed: 10/25/2022]
Abstract
Studies of sterile mutants in Caenorhabditis elegans have uncovered new insights into fundamental aspects of gamete cell biology, development, and function at fertilization. The genome sequences of C. elegans, Caenorhabditis briggsae and Caenorhabditis remanei allow for informative comparative studies among these three species. Towards that end, we have examined wild-type sperm morphology and activation (spermiogenesis) in each. Light and electron microscopy studies reveal that general sperm morphology, organization, and ultrastructure are similar in all three species, and activation techniques developed for C. elegans were found to work well in both C. briggsae and C. remanei. Despite important differences in the reproductive mode between C. remanei and the other two species, most genes required for spermiogenesis are conserved in all three. Finally, we have also examined the subcellular distribution of sperm epitopes in C. briggsae and C. remanei that cross-react with anti-sera directed against C. elegans sperm proteins. The baseline data in this study will prove useful for the future analysis and interpretation of sperm gene function across nematode species.
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Affiliation(s)
- Brian Geldziler
- Department of Genetics, Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA
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29
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Barrière A, Félix MA. High local genetic diversity and low outcrossing rate in Caenorhabditis elegans natural populations. Curr Biol 2005; 15:1176-84. [PMID: 16005289 DOI: 10.1016/j.cub.2005.06.022] [Citation(s) in RCA: 261] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 06/01/2005] [Accepted: 06/02/2005] [Indexed: 11/23/2022]
Abstract
BACKGROUND Caenorhabditis elegans is a major model system in biology, yet very little is known about its biology outside the laboratory. In particular, its unusual mode of reproduction with self-fertile hermaphrodites and facultative males raises the question of its frequency of outcrossing in natural populations. RESULTS We describe the first analysis of C. elegans individuals sampled directly from natural populations. C. elegans is found predominantly in the dauer stage and with a very low frequency of males versus hermaphrodites. Whereas C. elegans was previously shown to display a low worldwide genetic diversity, we find by comparison a surprisingly high local genetic diversity of C. elegans populations; this local diversity is contributed in great part by immigration of new alleles rather than by mutation. Our results on heterozygote frequency, male frequency, and linkage disequilibrium furthermore show that selfing is the predominant mode of reproduction in C. elegans natural populations but that infrequent outcrossing events occur, at a rate of approximately 1%. CONCLUSIONS Our results give a first insight in the biology of C. elegans in the natural populations. They demonstrate that local populations of C. elegans are genetically diverse and that a low frequency of outcrossing allows for the recombination of these locally diverse genotypes.
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Affiliation(s)
- Antoine Barrière
- Institut Jacques Monod, Centre National de la Recherche Scientifique, Universities Paris 6 and 7, Paris, France
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30
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Hong RL, Villwock A, Sommer RJ. Cultivation of the rhabditid Poikilolaimus oxycercus as a laboratory nematode for genetic analyses. ACTA ACUST UNITED AC 2005; 303:742-60. [PMID: 16106407 DOI: 10.1002/jez.a.200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vulva formation is a paradigm for evolutionary developmental biology in nematodes. Not only do the number of vulval precursor cells (VPCs) differ between members in the Rhabditidae and Diplogastridae, they are also sculpted via different developmental mechanisms, either by cell fusion in most Rhabditidae or by programmed cell death in the Diplogastridae. In this context, the species Poikilolaimus oxycercus is the only known species in the family Rhabditidae to have a subset of the Pn.p cells commit programmed cell death during the patterning of the VPCs. Our current study introduces P. oxycercus as a new laboratory organism. There are discrete laboratory strains that are genetically polymorphic from each other as well as heterogeneous within each strain. In order to cultivate this gonochoristic nematode into an experimental model with a tractable genetic system, we produced two inbreeding tolerant, near-isogenic strains capable of producing viable progeny with each other. We also described P. oxycera's morphology by scanning electron microscopy (SEM), basic life history traits, hybrid viability, and mating behavior. P. oxycercus females have no preference for inter- or intra-strain matings, and can mate with multiple males in a relatively short time period, suggesting a propensity for maintaining heterozygosity through promiscuity. Interestingly, all sexes from three species in the genus Poikilolaimus show five 4',6-diamidino-2-phenylindole (DAPI) staining bodies in their germ line cells. This could indicate that Poikilolaimus species possess five bivalent chromosomes in their germ lines, in contrast to the hermaphroditic Caenorhabditis elegans or Pristionchus pacificus, which have six chromosomes.
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Affiliation(s)
- Ray L Hong
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstrasse 37-39, 72076 Tuebingen, Germany.
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31
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Haag ES, Ackerman AD. Intraspecific variation in fem-3 and tra-2, two rapidly coevolving nematode sex-determining genes. Gene 2005; 349:35-42. [PMID: 15780968 DOI: 10.1016/j.gene.2004.12.051] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 12/16/2004] [Accepted: 12/27/2004] [Indexed: 11/30/2022]
Abstract
The sex determination gene fem-3 encodes one of the most divergent proteins yet described in the terrestrial nematode Caenorhabditis. Despite this rapid sequence change, however, FEM-3 is essential for male development in the three species surveyed thus far. It also participates in conserved protein-protein complexes with the transmembrane receptor TRA-2 and the phosphatase FEM-2 in these species. These interactions show strong species specificity, indicating that conserved residues are not sufficient for function and that compensatory evolution between binding partners is important. To shed further light on the nature of this coevolution, and to discern the extent of amino acid polymorphism allowed in FEM-3 and the domain of TRA-2 that binds it, we have examined intraspecific variation in the gonochoristic species Caenorhabditis remanei. Ten new complete Cr-fem-3 alleles from three regions of the United States are described. We also obtained sequences for the FEM-3-binding domain of TRA-2 for 9 of the same strains. These alleles were compared with each other, with the European founder alleles, and with the orthologous sequences from the congeners Caenorhabditis elegans and C. briggsae. We find that FEM-3 harbors abundant amino acid polymorphisms along its entire length. The majority (but not all) of these occur in nonconserved residues, and in at least one domain there is evidence for diversifying selection. The FEM-3-binding domain of TRA-2 is less polymorphic than FEM-3. Amino acids neither polymorphic nor conserved between species are candidates for residues mediating species-specific interaction of FEM-3 with its binding partners.
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Affiliation(s)
- Eric S Haag
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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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
A variety of models propose that the accumulation of deleterious mutations plays an important role in the evolution of breeding systems. These models make predictions regarding the relative rates of protein evolution and deleterious mutation in taxa with contrasting modes of reproduction. Here we compare available coding sequences from one obligately outcrossing and two primarily selfing species of Caenorhabditis to explore the potential for mutational models to explain the evolution of breeding system in this clade. If deleterious mutations interact synergistically, the mutational deterministic hypothesis predicts that a high genomic deleterious mutation rate (U) will offset the reproductive disadvantage of outcrossing relative to asexual or selfing reproduction. Therefore, C. elegans and C. briggsae (both largely selfing) should both exhibit lower rates of deleterious mutation than the obligately outcrossing relative C. remanei. Using a comparative approach, we estimate U to be equivalent (and < 1) among all three related species. Stochastic mutational models, Muller's ratchet and Hill-Robertson interference, are expected to cause reductions in the effective population size in species that rarely outcross, thereby allowing deleterious mutations to accumulate at an elevated rate. We find only limited support for more rapid molecular evolution in selfing lineages. Overall, our analyses indicate that the evolution of breeding system in this group is unlikely to be explained solely by available mutational models.
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Affiliation(s)
- A D Cutter
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
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Abstract
Many animal species exhibit sex differences in aging. In the nematode Caenorhabditis elegans, under conditions that minimize mortality, males are the longer-lived sex. In a survey of 12 independent C. elegans isolates, we find that this is a species-typical character. To test the hypothesis that the C. elegans male longevity bias evolved as a consequence of androdioecy (having males and hermaphrodites), we compared sex-specific survival in four androdioecious and four dioecious (males and females) nematode species. Contrary to expectation, in all but C. briggsae (androdioecious), males were the longer-lived sex, and this difference was greatest among dioecious species. Moreover, male lifespan was reduced in androdioecious species relative to dioecious species. The evolutionary theory of aging predicts the evolution of a shorter lifespan in the sex with the greater rate of extrinsic mortality. We demonstrate that in each of eight species early adult mortality is elevated in females/hermaphrodites in the absence of food as the consequence of internal hatching of larvae (matricide). This age-independent mortality risk can favour the evolution of rapid aging in females and hermaphrodites relative to males.
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Affiliation(s)
- Diana McCulloch
- Department of Biology, University College London, London WC 1E 6BT, UK
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36
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Affiliation(s)
- John R. Pannell
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom;
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37
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Rudel D, Kimble J. Evolution of discrete Notch-like receptors from a distant gene duplication in Caenorhabditis. Evol Dev 2002; 4:319-33. [PMID: 12356262 DOI: 10.1046/j.1525-142x.2002.02027.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY Caenorhabditis elegans possesses two Notch-like receptors, LIN-12 and GLP-1, which have both overlapping and individual biological functions. We examined the lin-12 and glp-1 genes in closely related nematodes to learn about their evolution. Here we report molecular and functional analyses of lin-12 orthologs from two related nematodes, C. briggsae (Cb) and C. remanei (Cr). In addition, we compare these lin-12 findings with similar studies of Cb-glp-1 and Cr-glp-1 orthologs. Cb-LIN-12 and Cr-LIN-12 retain the same number and order of motifs as Ce-LIN-12. Intriguingly, we find that LIN-12 conservation differs from that of GLP-1 in two respects. First, individual motifs are conserved to a different degree for the two receptors. For example, the transmembrane domain is 16-32% identical among LIN-12 orthologs but 65-70% identical among GLP-1 orthologs. Second, certain amino acids are conserved in a receptor-specific manner, a phenomenon most prevalent in the CC-linker. We suggest that LIN-12 and GLP-1 have been molded by selective constraints that are receptor specific and that the two proteins may not be entirely interchangeable. To analyze the functions of the lin-12 orthologs, we used RNA-mediated interference (RNAi). Cb-lin-12(RNAi) or Cr-lin-12(RNAi) progeny are nearly 100% Lag, a larval lethality typical of C. elegans lin-12 glp-1 double mutants, but not the primary defect observed in Ce-lin-12 null mutants or Ce-lin-12(RNAi). Therefore, LIN-12 functions are similar, but not identical, among the Caenorhabditis species. We suggest that ancestral functions may have been divided between LIN-12 and GLP-1 receptors in a process contributing to the retention of both genes after gene duplication (i.e., subfunctionalization).
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Affiliation(s)
- David Rudel
- Department of Biochemistry, University of Wisconsin-Madison, 53706, USA
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38
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Abstract
Haldane's rule in C. briggsae x C. remanei broods was caused by sexual transformation; XX and XO hybrids were female. C. briggsae and C. remanei variants that partially suppress hybrid sexual transformation were identified. Effects of variant strains were cumulative. Hence, aberrant sex determination is a reproductive isolation mechanism in Caenorhabditis.
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Affiliation(s)
- Scott Everet Baird
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435-0001, USA.
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39
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Graustein A, Gaspar JM, Walters JR, Palopoli MF. Levels of DNA polymorphism vary with mating system in the nematode genus caenorhabditis. Genetics 2002; 161:99-107. [PMID: 12019226 PMCID: PMC1462083 DOI: 10.1093/genetics/161.1.99] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Self-fertilizing species often harbor less genetic variation than cross-fertilizing species, and at least four different models have been proposed to explain this trend. To investigate further the relationship between mating system and genetic variation, levels of DNA sequence polymorphism were compared among three closely related species in the genus Caenorhabditis: two self-fertilizing species, Caenorhabditis elegans and C. briggsae, and one cross-fertilizing species, C. remanei. As expected, estimates of silent site nucleotide diversity were lower in the two self-fertilizing species. For the mitochondrial genome, diversity in the selfing species averaged 42% of diversity in C. remanei. Interestingly, the reduction in genetic variation was much greater for the nuclear than for the mitochondrial genome. For two nuclear genes, diversity in the selfing species averaged 6 and 13% of diversity in C. remanei. We argue that either population bottlenecks or the repeated action of natural selection, coupled with high levels of selfing, are likely to explain the observed reductions in species-wide genetic diversity.
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Affiliation(s)
- Andrew Graustein
- Department of Biology, Bowdoin College, Brunswick, Maine 04011, USA
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40
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Abstract
Comparisons between related species often allow the detailed genetic analysis of evolutionary processes. Here we advocate the use of the nematode Caenorhabditis elegans (and several other rhabditid species) as model systems for microevolutionary studies. Compared to Drosophila species, which have been a mainstay of such studies, C. elegans has a self-fertilizing mode of reproduction, a shorter life cycle and a convenient cell-level analysis of phenotypic variation. Data concerning its population genetics and ecology are still scarce, however. We review molecular, behavioral and developmental intraspecific polymorphisms for populations of C. elegans, Oscheius sp. 1 and Pristionchus pacificus. Focusing on vulval development, which has been well characterized in several species, we discuss relationships between patterns of variations: (1) for a given genotype (developmental variants), (2) after mutagenesis (mutability), (3) in different populations of the same species (polymorphisms) and (4) between closely related species. These studies have revealed that evolutionary variations between sister species affect those characters that show phenotypic developmental variants, that are mutable and that are polymorphic within species.
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Affiliation(s)
- M Delattre
- Institut Jacques Monod, CNRS, Universités de Paris 6 et 7, Tour 43, 2 place Jussieu, 75251 Paris cedex 05, France
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41
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Chen PJ, Cho S, Jin SW, Ellis RE. Specification of germ cell fates by FOG-3 has been conserved during nematode evolution. Genetics 2001; 158:1513-25. [PMID: 11514443 PMCID: PMC1461761 DOI: 10.1093/genetics/158.4.1513] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Rapid changes in sexual traits are ubiquitous in evolution. To analyze this phenomenon, we are studying species of the genus Caenorhabditis. These animals use one of two different mating systems-male/hermaphroditic, like the model organism Caenorhabditis elegans, or male/female, like C. remanei. Since hermaphrodites are essentially females that produce sperm for self-fertilization, elucidating the control of cell fate in the germ line in each species could provide the key to understanding how these mating systems evolved. In C. elegans, FOG-3 is required to specify that germ cells become sperm. Thus, we cloned its homologs from both C. remanei and C. briggsae. Each species produces a single homolog of FOG-3, and RNA-mediated interference indicates that FOG-3 functions in each species to specify that germ cells develop as sperm rather than as oocytes. What factors account for the different mating systems? Northern analyses and RT-PCR data reveal that the expression of fog-3 is always correlated with spermatogenesis. Since the promoters for all three fog-3 genes contain binding sites for the transcription factor TRA-1A and are capable of driving expression of fog-3 in C. elegans hermaphrodites, we propose that alterations in the upstream sex-determination pathway, perhaps acting through TRA-1A, allow spermatogenesis in C. elegans and C. briggsae XX larvae but not in C. remanei.
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Affiliation(s)
- P J Chen
- Department of Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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42
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Delattre M, Félix MA. Polymorphism and evolution of vulval precursor cell lineages within two nematode genera, Caenorhabditis and Oscheius. Curr Biol 2001; 11:631-43. [PMID: 11369226 DOI: 10.1016/s0960-9822(01)00202-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The cell lineage of nematodes is mostly invariant for a given species, but varies between species. One can thus wonder how a cell lineage varies during evolution. We have started a microevolutionary approach within two genera by observing lineage variations of vulval precursor cells in different natural nematode populations of the same and closely related species. RESULTS In Caenorhabditis elegans, the P3.p cell lineage is variable within a genetically homogeneous population and polymorphic between wild strains. Irrespective of its division pattern, P3.p is competent to form vulval tissue in different C. elegans strains, whereas it is not competent in C. briggsae. In Oscheius sp. 1, P4.p and P8.p lineages are strongly polymorphic. Within each genus, these intraspecies polymorphisms in cell lineages are amplified between closely related species. In Oscheius sp. 1, the large polymorphisms in P4.p and P8.p lineages allowed us to undertake a genetic analysis of the variation between two pairs of strains. Multiple loci are involved in cell lineage differences, and variation at one locus appears to have a relatively strong effect. In addition to these large lineage variations in cells that do not normally contribute to the vulva, we find minor variations (errors) in vulval lineages, which represent the precision level of the vulval-patterning process and point to a selection pressure for maintenance of a large vulval equivalence group. CONCLUSIONS Polymorphisms in vulval cell lineage are found within a given nematode species, and could be instrumental in explaining evolutionary variations between closely related species.
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Affiliation(s)
- M Delattre
- Institut Jacques Monod, CNRS, Universités de Paris 6 et 7, Tour 43, 2 place Jussieu, 75251 cedex 05, Paris, France
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43
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Srinivasan J, Pires-daSilva A, Gutierrez A, Zheng M, Jungblut B, Witte H, Schlak I, Sommer RJ. Microevolutionary analysis of the nematode genus Pristionchus suggests a recent evolution of redundant developmental mechanisms during vulva formation. Evol Dev 2001; 3:229-40. [PMID: 11478520 DOI: 10.1046/j.1525-142x.2001.003004229.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To identify the mechanisms by which molecular variation is introduced into developmental systems, microevolutionary approaches to evolutionary developmental biology have to be taken. Here, we describe the molecular and developmental characterization of laboratory strains of the nematode genus Pristionchus, which lays a foundation for a microevolutionary analysis of vulva development. We describe 13 laboratory strains of the Pristionchus genus that are derived from natural isolates from around the world. Mating experiments and ITS sequence analysis indicated that these 13 strains represent four different species: the gonochoristic species P. Iheritieriand three hermaphroditic species, P. pacificus, P. maupasi, and an as yet undescribed species Pristionchus sp., respectively. P. pacificus is represented by five different strains isolated from California, Washington, Hawaii, Ontario, and Poland. Developmental differences during vulva formation are observed between strains from different species but also between strains of P. pacificus, like the strains from California and Poland. In particular, redundant developmental mechanisms present during vulva formation in P. pacificus var. California are absent in other strains. Amplified restriction fragment length polymorphism (AFLP) analyses of the P. pacificus strains revealed that the American strains are highly polymorphic. In contrast, the developmentally distinct strain from Poland is identical to the Californian strain, suggesting that the developmental differences rely on a small number of changes in developmental control genes rather than the accumulation of changes at multiple loci.
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Affiliation(s)
- J Srinivasan
- Max-Planck Institut für Entwicklungsbiologie, Abteilung Evolutionsbiologie, Tübingen, Germany
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44
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Haag ES, Kimble J. Regulatory elements required for development of caenorhabditis elegans hermaphrodites are conserved in the tra-2 homologue of C. remanei, a male/female sister species. Genetics 2000; 155:105-16. [PMID: 10790387 PMCID: PMC1461077 DOI: 10.1093/genetics/155.1.105] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The Caenorhabditis elegans hermaphrodite is essentially a female that produces sperm. In C. elegans, tra-2 promotes female fates and must be repressed to achieve hermaphrodite spermatogenesis. In an effort to learn how mating systems evolve, we have cloned tra-2 from C. remanei, the closest gonochoristic relative of C. elegans. We found its structure to be similar to that of Ce-tra-2 but its sequence to be divergent. RNA interference demonstrates that Cr-tra-2 promotes female fates. Two sites of tra-2 regulation are required for the onset of hermaphrodite spermatogenesis in C. elegans. One, the MX region of TRA-2, is as well conserved in C. remanei as it is in C. briggsae (another male/hermaphrodite species), suggesting that this control is not unique to hermaphrodites. Another, the DRE/TGE element of the tra-2 3' UTR, was not detected by sequence analysis. However, gel-shift assays demonstrate that a factor in C. remanei can bind specifically to the Cr-tra-2 3' UTR, suggesting that this translational control is also conserved. We propose that both controls are general and do not constitute a novel "switch" that enables sexual mosaicism in hermaphrodites. However, subtle quantitative or qualitative differences in their employment may underlie differences in mating system seen in Caenorhabditis.
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Affiliation(s)
- E S Haag
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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45
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Abstract
Several interspecific combinations of the "elegans" group of Caenorhabditis species are cross-fertile. Most F1 hybrids from these crosses arrest during embryogenesis. Developmental defects observed in hybrid embryos include defects in gastrulation initiation, defects in embryonic compaction, and defects in embryonic elongation. These reproductive barriers have arisen multiple times in the evolution of Caenorhabditis.
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Affiliation(s)
- S E Baird
- Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA.
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46
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Baldwin JG, Frisse LM, Vida JT, Eddleman CD, Thomas WK. An evolutionary framework for the study of developmental evolution in a set of nematodes related to Caenorhabditis elegans. Mol Phylogenet Evol 1997; 8:249-59. [PMID: 9299229 DOI: 10.1006/mpev.1997.0433] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nematodes are known to be a useful system for studies of comparative development. Here we perform a molecular phylogenetic analysis to allow for the independent interpretation of the developmental and morphological changes observed among a selected set of nematode species. Our molecular phylogenetic analysis is based on coding regions of the genes for RNA polymerase II, the small subunit rRNA and an expansion segment of the large subunit rRNA. Sequences were compared from five species in the family (Rhabditidae) that includes the developmental model organism Caenorhabditis elegans and from an outgroup taxon Aduncospiculum halicti (Diplogasterina). The phylogenetic analysis does not support the monophyly of the subfamily Mesorhabditinae and identifies the unnamed strain PS1010 as a sister taxon of C. elegans despite its morphologically divergent buccal capsule. On the basis of the inferred framework, we can begin to interpret the evolution of vulval development and of morphological differences among these nematode species.
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Affiliation(s)
- J G Baldwin
- Department of Nematology, University of California, Riverside, California 92521, USA
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