1
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Xie D, Gu B, Liu Y, Ye P, Ma Y, Wen T, Song X, Zhao Z. Efficient targeted recombination with CRISPR/Cas9 in hybrids of Caenorhabditis nematodes with suppressed recombination. BMC Biol 2023; 21:203. [PMID: 37775783 PMCID: PMC10542263 DOI: 10.1186/s12915-023-01704-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023] Open
Abstract
BACKGROUND Homology-based recombination (HR) is the cornerstone of genetic mapping. However, a lack of sufficient sequence homology or the presence of a genomic rearrangement prevents HR through crossing, which inhibits genetic mapping in relevant genomic regions. This is particularly true in species hybrids whose genomic sequences are highly divergent along with various genome arrangements, making the mapping of genetic loci, such as hybrid incompatibility (HI) loci, through crossing impractical. We previously mapped tens of HI loci between two nematodes, Caenorhabditis briggsae and C. nigoni, through the repeated backcrossing of GFP-linked C. briggsae fragments into C. nigoni. However, the median introgression size was over 7 Mb, indicating apparent HR suppression and preventing the subsequent cloning of the causative gene underlying a given HI phenotype. Therefore, a robust method that permits recombination independent of sequence homology is desperately desired. RESULTS Here, we report a method of highly efficient targeted recombination (TR) induced by CRISPR/Cas9 with dual guide RNAs (gRNAs), which circumvents the HR suppression in hybrids between the two species. We demonstrated that a single gRNA was able to induce efficient TR between highly homologous sequences only in the F1 hybrids but not in the hybrids that carry a GFP-linked C. briggsae fragment in an otherwise C. nigoni background. We achieved highly efficient TR, regardless of sequence homology or genetic background, when dual gRNAs were used that each specifically targeted one parental chromosome. We further showed that dual gRNAs were able to induce efficient TR within genomic regions that had undergone inversion, in which HR-based recombination was expected to be suppressed, supporting the idea that dual-gRNA-induced TR can be achieved through nonhomology-based end joining between two parental chromosomes. CONCLUSIONS Recombination suppression can be circumvented through CRISPR/Cas9 with dual gRNAs, regardless of sequence homology or the genetic background of the species hybrid. This method is expected to be applicable to other situations in which recombination is suppressed in interspecies or intrapopulation hybrids.
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Affiliation(s)
- Dongying Xie
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Bida Gu
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, USA
| | - Yiqing Liu
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Pohao Ye
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Yiming Ma
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Tongshu Wen
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Xiaoyuan Song
- MOE Key Laboratory of Cellular Dynamics, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230026, Anhui, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China.
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2
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Cutter AD. Speciation and development. Evol Dev 2023; 25:289-327. [PMID: 37545126 DOI: 10.1111/ede.12454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/13/2023] [Accepted: 07/20/2023] [Indexed: 08/08/2023]
Abstract
Understanding general principles about the origin of species remains one of the foundational challenges in evolutionary biology. The genomic divergence between groups of individuals can spawn hybrid inviability and hybrid sterility, which presents a tantalizing developmental problem. Divergent developmental programs may yield either conserved or divergent phenotypes relative to ancestral traits, both of which can be responsible for reproductive isolation during the speciation process. The genetic mechanisms of developmental evolution involve cis- and trans-acting gene regulatory change, protein-protein interactions, genetic network structures, dosage, and epigenetic regulation, all of which also have roots in population genetic and molecular evolutionary processes. Toward the goal of demystifying Darwin's "mystery of mysteries," this review integrates microevolutionary concepts of genetic change with principles of organismal development, establishing explicit links between population genetic process and developmental mechanisms in the production of macroevolutionary pattern. This integration aims to establish a more unified view of speciation that binds process and mechanism.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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3
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Ding Q, Ren X, Li R, Chan L, Ho VWS, Bi Y, Xie D, Zhao Z. Highly efficient transgenesis with miniMos in Caenorhabditis briggsae. G3 (BETHESDA, MD.) 2022; 12:jkac254. [PMID: 36171682 PMCID: PMC9713419 DOI: 10.1093/g3journal/jkac254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/29/2022] [Indexed: 06/13/2023]
Abstract
Caenorhabditis briggsae as a companion species for Caenorhabditis elegans has played an increasingly important role in study of evolution of development and genome and gene regulation. Aided by the isolation of its sister spices, it has recently been established as a model for speciation study. To take full advantage of the species for comparative study, an effective transgenesis method especially those with single-copy insertion is important for functional comparison. Here, we improved a transposon-based transgenesis methodology that had been originally developed in C. elegans but worked marginally in C. briggsae. By incorporation of a heat shock step, the transgenesis efficiency in C. briggsae with a single-copy insertion is comparable to that in C. elegans. We used the method to generate 54 independent insertions mostly consisting of a mCherry tag over the C. briggsae genome. We demonstrated the use of the tags in identifying interacting loci responsible for hybrid male sterility between C. briggsae and Caenorhabditis nigoni when combined with the GFP tags we generated previously. Finally, we demonstrated that C. briggsae tolerates the C. elegans toxin, PEEL-1, but not SUP-35, making the latter a potential negative selection marker against extrachromosomal array.
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Affiliation(s)
- Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Luyan Chan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Vincy W S Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yu Bi
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Dongying Xie
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong SAR, China
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4
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Xie D, Ye P, Ma Y, Li Y, Liu X, Sarkies P, Zhao Z. Genetic exchange with an outcrossing sister species causes severe genome-wide dysregulation in a selfing Caenorhabditis nematode. Genome Res 2022; 32:2015-2027. [PMID: 36351773 PMCID: PMC9808620 DOI: 10.1101/gr.277205.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Different modes of reproduction evolve rapidly, with important consequences for genome composition. Selfing species often occupy a similar niche as their outcrossing sister species with which they are able to mate and produce viable hybrid progeny, raising the question of how they maintain genomic identity. Here, we investigate this issue by using the nematode Caenorhabditis briggsae, which reproduces as a hermaphrodite, and its outcrossing sister species Caenorhabditis nigoni We hypothesize that selfing species might develop some barriers to prevent gene intrusions through gene regulation. We therefore examined gene regulation in the hybrid F2 embryos resulting from reciprocal backcrosses between F1 hybrid progeny and C. nigoni or C. briggsae F2 hybrid embryos with ∼75% of their genome derived from C. briggsae (termed as bB2) were inviable, whereas those with ∼75% of their genome derived from C. nigoni (termed as nB2) were viable. Misregulation of transposable elements, coding genes, and small regulatory RNAs was more widespread in the bB2 compared with the nB2 hybrids, which is a plausible explanation for the differential phenotypes between the two hybrids. Our results show that regulation of the C. briggsae genome is strongly affected by genetic exchanges with its outcrossing sister species, C. nigoni, whereas regulation of the C. nigoni genome is more robust on genetic exchange with C. briggsae The results provide new insights into how selfing species might maintain their identity despite genetic exchanges with closely related outcrossing species.
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Affiliation(s)
- Dongying Xie
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Pohao Ye
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yiming Ma
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yongbin Li
- College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Xiao Liu
- College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Peter Sarkies
- Department of Biochemistry, University of Oxford, Oxford, OX1 4BH, United Kingdom
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China;,State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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5
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Banho CA, Mérel V, Oliveira TYK, Carareto CMA, Vieira C. Comparative transcriptomics between Drosophila mojavensis and D. arizonae reveals transgressive gene expression and underexpression of spermatogenesis-related genes in hybrid testes. Sci Rep 2021; 11:9844. [PMID: 33972659 PMCID: PMC8110761 DOI: 10.1038/s41598-021-89366-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/19/2021] [Indexed: 01/02/2023] Open
Abstract
Interspecific hybridization is a stressful condition that can lead to sterility and/or inviability through improper gene regulation in Drosophila species with a high divergence time. However, the extent of these abnormalities in hybrids of recently diverging species is not well known. Some studies have shown that in Drosophila, the mechanisms of postzygotic isolation may evolve more rapidly in males than in females and that the degree of viability and sterility is associated with the genetic distance between species. Here, we used transcriptomic comparisons between two Drosophila mojavensis subspecies and D. arizonae (repleta group, Drosophila) and identified greater differential gene expression in testes than in ovaries. We tested the hypothesis that the severity of the interspecies hybrid phenotype is associated with the degree of gene misregulation. We showed limited gene misregulation in fertile females and an increase in the amount of misregulation in males with more severe sterile phenotypes (motile vs. amotile sperm). In addition, for these hybrids, we identified candidate genes that were mostly associated with spermatogenesis dysfunction.
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Affiliation(s)
- Cecilia A Banho
- Department of Biology, UNESP - São Paulo State University, São José do Rio Preto, São Paulo State (SP), Brazil.,Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France
| | - Vincent Mérel
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France
| | - Thiago Y K Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY, USA
| | - Claudia M A Carareto
- Department of Biology, UNESP - São Paulo State University, São José do Rio Preto, São Paulo State (SP), Brazil
| | - Cristina Vieira
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France.
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6
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Sánchez-Ramírez S, Weiss JG, Thomas CG, Cutter AD. Widespread misregulation of inter-species hybrid transcriptomes due to sex-specific and sex-chromosome regulatory evolution. PLoS Genet 2021; 17:e1009409. [PMID: 33667233 PMCID: PMC7968742 DOI: 10.1371/journal.pgen.1009409] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 03/17/2021] [Accepted: 02/09/2021] [Indexed: 01/04/2023] Open
Abstract
When gene regulatory networks diverge between species, their dysfunctional expression in inter-species hybrid individuals can create genetic incompatibilities that generate the developmental defects responsible for intrinsic post-zygotic reproductive isolation. Both cis- and trans-acting regulatory divergence can be hastened by directional selection through adaptation, sexual selection, and inter-sexual conflict, in addition to cryptic evolution under stabilizing selection. Dysfunctional sex-biased gene expression, in particular, may provide an important source of sexually-dimorphic genetic incompatibilities. Here, we characterize and compare male and female/hermaphrodite transcriptome profiles for sibling nematode species Caenorhabditis briggsae and C. nigoni, along with allele-specific expression in their F1 hybrids, to deconvolve features of expression divergence and regulatory dysfunction. Despite evidence of widespread stabilizing selection on gene expression, misexpression of sex-biased genes pervades F1 hybrids of both sexes. This finding implicates greater fragility of male genetic networks to produce dysfunctional organismal phenotypes. Spermatogenesis genes are especially prone to high divergence in both expression and coding sequences, consistent with a "faster male" model for Haldane's rule and elevated sterility of hybrid males. Moreover, underdominant expression pervades male-biased genes compared to female-biased and sex-neutral genes and an excess of cis-trans compensatory regulatory divergence for X-linked genes underscores a "large-X effect" for hybrid male expression dysfunction. Extensive regulatory divergence in sex determination pathway genes likely contributes to demasculinization of XX hybrids. The evolution of genetic incompatibilities due to regulatory versus coding sequence divergence, however, are expected to arise in an uncorrelated fashion. This study identifies important differences between the sexes in how regulatory networks diverge to contribute to sex-biases in how genetic incompatibilities manifest during the speciation process.
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Affiliation(s)
- Santiago Sánchez-Ramírez
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- * E-mail: (SSR); (ADC)
| | - Jörg G. Weiss
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Cristel G. Thomas
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Asher D. Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
- * E-mail: (SSR); (ADC)
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7
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Abstract
New species arise as the genomes of populations diverge. The developmental 'alarm clock' of speciation sounds off when sufficient divergence in genetic control of development leads hybrid individuals to infertility or inviability, the world awoken to the dawn of new species with intrinsic post-zygotic reproductive isolation. Some developmental stages will be more prone to hybrid dysfunction due to how molecular evolution interacts with the ontogenetic timing of gene expression. Considering the ontogeny of hybrid incompatibilities provides a profitable connection between 'evo-devo' and speciation genetics to better link macroevolutionary pattern, microevolutionary process, and molecular mechanisms. Here, we explore speciation alongside development, emphasizing their mutual dependence on genetic network features, fitness landscapes, and developmental system drift. We assess models for how ontogenetic timing of reproductive isolation can be predictable. Experiments and theory within this synthetic perspective can help identify new rules of speciation as well as rules in the molecular evolution of development.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of TorontoTorontoCanada
| | - Joanna D Bundus
- Department of Integrative Biology, University of Wisconsin – MadisonMadisonUnited States
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8
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Li R, Ren X, Ding Q, Bi Y, Xie D, Zhao Z. Direct full-length RNA sequencing reveals unexpected transcriptome complexity during Caenorhabditis elegans development. Genome Res 2020; 30:287-298. [PMID: 32024662 PMCID: PMC7050527 DOI: 10.1101/gr.251512.119] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 12/18/2019] [Indexed: 01/08/2023]
Abstract
Massively parallel sequencing of the polyadenylated RNAs has played a key role in delineating transcriptome complexity, including alternative use of an exon, promoter, 5′ or 3′ splice site or polyadenylation site, and RNA modification. However, reads derived from the current RNA-seq technologies are usually short and deprived of information on modification, compromising their potential in defining transcriptome complexity. Here, we applied a direct RNA sequencing method with ultralong reads using Oxford Nanopore Technologies to study the transcriptome complexity in Caenorhabditis elegans. We generated approximately six million reads using native poly(A)-tailed mRNAs from three developmental stages, with average read lengths ranging from 900 to 1100 nt. Around half of the reads represent full-length transcripts. To utilize the full-length transcripts in defining transcriptome complexity, we devised a method to classify the long reads as the same as existing transcripts or as a novel transcript using sequence mapping tracks rather than existing intron/exon structures, which allowed us to identify roughly 57,000 novel isoforms and recover at least 26,000 out of the 33,500 existing isoforms. The sets of genes with differential expression versus differential isoform usage over development are largely different, implying a fine-tuned regulation at isoform level. We also observed an unexpected increase in putative RNA modification in all bases in the coding region relative to the UTR, suggesting their possible roles in translation. The RNA reads and the method for read classification are expected to deliver new insights into RNA processing and modification and their underlying biology in the future.
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Affiliation(s)
- Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Yu Bi
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Dongying Xie
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, 999077, China.,State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, 999077, China
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9
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Cutter AD, Morran LT, Phillips PC. Males, Outcrossing, and Sexual Selection in Caenorhabditis Nematodes. Genetics 2019; 213:27-57. [PMID: 31488593 PMCID: PMC6727802 DOI: 10.1534/genetics.119.300244] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 06/06/2019] [Indexed: 12/15/2022] Open
Abstract
Males of Caenorhabditis elegans provide a crucial practical tool in the laboratory, but, as the rarer and more finicky sex, have not enjoyed the same depth of research attention as hermaphrodites. Males, however, have attracted the attention of evolutionary biologists who are exploiting the C. elegans system to test longstanding hypotheses about sexual selection, sexual conflict, transitions in reproductive mode, and genome evolution, as well as to make new discoveries about Caenorhabditis organismal biology. Here, we review the evolutionary concepts and data informed by study of males of C. elegans and other Caenorhabditis We give special attention to the important role of sperm cells as a mediator of inter-male competition and male-female conflict that has led to drastic trait divergence across species, despite exceptional phenotypic conservation in many other morphological features. We discuss the evolutionary forces important in the origins of reproductive mode transitions from males being common (gonochorism: females and males) to rare (androdioecy: hermaphrodites and males) and the factors that modulate male frequency in extant androdioecious populations, including the potential influence of selective interference, host-pathogen coevolution, and mutation accumulation. Further, we summarize the consequences of males being common vs rare for adaptation and for trait divergence, trait degradation, and trait dimorphism between the sexes, as well as for molecular evolution of the genome, at both micro-evolutionary and macro-evolutionary timescales. We conclude that C. elegans male biology remains underexploited and that future studies leveraging its extensive experimental resources are poised to discover novel biology and to inform profound questions about animal function and evolution.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Ontario M5S3B2, Canada
| | - Levi T Morran
- Department of Biology, Emory University, Atlanta, Georgia 30322, and
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403
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10
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Li R, Ren X, Bi Y, Ding Q, Ho VWS, Zhao Z. Comparative mitochondrial genomics reveals a possible role of a recent duplication of NADH dehydrogenase subunit 5 in gene regulation. DNA Res 2018; 25:577-586. [PMID: 30085012 PMCID: PMC6289777 DOI: 10.1093/dnares/dsy026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 07/22/2018] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial genome (mtDNA) carries not only well-conserved protein coding, tRNA and rRNA genes, but also highly variable non-coding regions (NCRs). However, the NCRs show poor conservation across species, making their function and evolution elusive. Identification and functional characterization of NCRs across species would be critical for addressing these questions. To this end, we devised a computational pipeline and performed de novo assembly and annotation of mtDNA from 19 Caenorhabditis species using next-generation sequencing (NGS) data. The mtDNAs for 14 out of the 19 species are reported for the first time. Comparison of the 19 genomes reveals species-specific sampling of partial displacement-loop (D-loop) sequence as a novel NCR inserted into a unique tRNA cluster, suggesting an important role of the D-loop and the tRNA cluster in shaping NCR evolution. Intriguingly, RNA-Seq analysis suggests that a novel NCR resulting from a recent duplication of NADH dehydrogenase subunit 5 (ND5) could be utilized as a 3' UTR for up-regulation of its upstream gene. The expression analysis shows a species- and sex-specific expression of mitochondrial genes encoded by mtDNA and nucleus, respectively. Our analyses provide important insights into the function and evolution of mitochondrial NCRs and pave the way for further studying the function and evolution of mitochondrial genome.
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Affiliation(s)
- Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yu Bi
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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11
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Bundus JD, Wang D, Cutter AD. Genetic basis to hybrid inviability is more complex than hybrid male sterility in Caenorhabditis nematodes. Heredity (Edinb) 2018; 121:169-182. [PMID: 29626207 PMCID: PMC6039526 DOI: 10.1038/s41437-018-0069-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/22/2018] [Accepted: 02/11/2018] [Indexed: 12/31/2022] Open
Abstract
Hybrid male sterility often evolves before female sterility or inviability of hybrids, implying that the accumulation of divergence between separated lineages should lead hybrid male sterility to have a more polygenic basis. However, experimental evidence is mixed. Here, we use the nematodes Caenorhabditis remanei and C. latens to characterize the underlying genetic basis of asymmetric hybrid male sterility and hybrid inviability. We demonstrate that hybrid male sterility is consistent with a simple genetic basis, involving a single X-autosome incompatibility. We also show that hybrid inviability involves more genomic compartments, involving diverse nuclear-nuclear incompatibilities, a mito-nuclear incompatibility, and maternal effects. These findings demonstrate that male sensitivity to genetic perturbation may be genetically simple compared to hybrid inviability in Caenorhabditis and motivates tests of generality for the genetic architecture of hybrid incompatibility across the breadth of phylogeny.
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Affiliation(s)
- Joanna D Bundus
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Donglin Wang
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Asher D Cutter
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada.
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12
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Ren X, Li R, Wei X, Bi Y, Ho V, Ding Q, Xu Z, Zhang Z, Hsieh CL, Young A, Zeng J, Liu X, Zhao Z. Genomic basis of recombination suppression in the hybrid between Caenorhabditis briggsae and C. nigoni. Nucleic Acids Res 2018; 46:1295-1307. [PMID: 29325078 PMCID: PMC5814819 DOI: 10.1093/nar/gkx1277] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 12/07/2017] [Accepted: 12/19/2017] [Indexed: 02/06/2023] Open
Abstract
DNA recombination is required for effective segregation and diversification of genomes and for the successful completion of meiosis. Recent studies in various species hybrids have demonstrated a genetic link between DNA recombination and speciation. Consistent with this, we observed a striking suppression of recombination in the hybrids between two nematodes, the hermaphroditic Caenorhabditis briggsae and the gonochoristic C. nigoni. To unravel the molecular basis underlying the recombination suppression in their hybrids, we generated a C. nigoni genome with chromosome-level contiguity and produced an improved C. briggsae genome with resolved gaps up to 2.8 Mb. The genome alignment reveals not only high sequence divergences but also pervasive intra- and inter-chromosomal sequence re-arrangements between the two species, which are plausible culprits for the observed suppression. Comparison of recombination boundary sequences suggests that recombination in the hybrid requires extensive sequence homology, which is rarely seen between the two genomes. The new genomes and genomic libraries form invaluable resources for studying genome evolution, hybrid incompatibilities and sex evolution for this pair of model species.
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Affiliation(s)
- Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaolin Wei
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- PTN (Peking University-Tsinghua University-National Institute of Biological Sciences) Joint Graduate Program, Beijing 100084, China
- School of Life Sciences, Peking University, Beijing 100871, China
| | - Yu Bi
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Zhichao Xu
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhihong Zhang
- Illumina Inc., 5200 Illumina Way, San Diego 92122, USA
| | | | - Amanda Young
- Illumina Inc., 5200 Illumina Way, San Diego 92122, USA
| | - Jianyang Zeng
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao Liu
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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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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14
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Cutter AD. X exceptionalism in Caenorhabditis speciation. Mol Ecol 2017; 27:3925-3934. [PMID: 29134711 DOI: 10.1111/mec.14423] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 12/13/2022]
Abstract
Speciation genetics research in diverse organisms shows the X-chromosome to be exceptional in how it contributes to "rules" of speciation. Until recently, however, the nematode phylum has been nearly silent on this issue, despite the model organism Caenorhabditis elegans having touched most other topics in biology. Studies of speciation with Caenorhabditis accelerated with the recent discovery of species pairs showing partial interfertility. The resulting genetic analyses of reproductive isolation in nematodes demonstrate key roles for the X-chromosome in hybrid male sterility and inviability, opening up new understanding of the genetic causes of Haldane's rule, Darwin's corollary to Haldane's rule, and enabling tests of the large-X effect hypothesis. Studies to date implicate improper chromatin regulation of the X-chromosome by small RNA pathways as integral to hybrid male dysfunction. Sexual transitions in reproductive mode to self-fertilizing hermaphroditism inject distinctive molecular evolutionary features into the speciation process for some species. Caenorhabditis also provides unique opportunities for analysis in a system with XO sex determination that lacks a Y-chromosome, sex chromosome-dependent sperm competition differences and mechanisms of gametic isolation, exceptional accessibility to the development process and rapid experimental evolution. As genetic analysis of reproductive isolation matures with investigation of multiple pairs of Caenorhabditis species and new species discovery, nematodes will provide a powerful complement to more established study organisms for deciphering the genetic basis of and rules to speciation.
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Affiliation(s)
- Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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15
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Le TS, Yang FJ, Lo YH, Chang TC, Hsu JC, Kao CY, Wang J. Non-Mendelian assortment of homologous autosomes of different sizes in males is the ancestral state in the Caenorhabditis lineage. Sci Rep 2017; 7:12819. [PMID: 28993668 PMCID: PMC5634442 DOI: 10.1038/s41598-017-13215-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 09/19/2017] [Indexed: 01/25/2023] Open
Abstract
Organismal genome sizes vary by six orders of magnitude and appear positively correlated with organismal size and complexity. Neutral models have been proposed to explain the broad patterns of genome size variation based on organism population sizes. In the Caenorhabditis genus, hermaphrodite genomes are smaller than those of gonochoristic species. One possible driving force for this genome size difference could be non-random chromosome segregation. In Caenorhabditis elegans, chromosome assortment is non-independent and violates Mendel's second law. In males, the shorter homologue of a heterozygous autosome pair preferentially co-segregates with the X chromosome while the longer one preferentially co-segregates with the nullo-X (O) chromosome in a process we call "skew". Since hermaphrodites preferentially receive the shorter chromosomes and can start populations independently, their genome size would be predicted to decrease over evolutionary time. If skew is an important driver for genome size reduction in hermaphroditic Caenorhabditis species, then it should be present in all congeneric species. In this study, we tested this hypothesis and found that skew is present in all eight examined species. Our results suggest that skew is likely the ancestral state in this genus. More speculatively, skew may drive genome size patterns in hermaphroditic species in other nematodes.
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Affiliation(s)
- Tho Son Le
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan.,Department of Molecular Genetics and Gene Technology, College of Forestry Biotechnology, Vietnam National University of Forestry, Hanoi, Vietnam
| | - Fang-Jung Yang
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Yun-Hua Lo
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Tiffany C Chang
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Jung-Chen Hsu
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Chia-Yi Kao
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei, 11529, Taiwan.
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16
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Dion-Côté AM, Barbash DA. Beyond speciation genes: an overview of genome stability in evolution and speciation. Curr Opin Genet Dev 2017; 47:17-23. [PMID: 28830007 DOI: 10.1016/j.gde.2017.07.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/17/2017] [Accepted: 07/28/2017] [Indexed: 01/03/2023]
Abstract
Genome stability ensures individual fitness and reliable transmission of genetic information. Hybridization between diverging lineages can trigger genome instability, highlighting its potential role in post-zygotic reproductive isolation. We argue that genome instability is not merely one of several types of hybrid incompatibility, but rather that genome stability is one of the very first and most fundamental traits that can break down when two diverged genomes are combined. Future work will reveal how frequent and predictable genome instability is in hybrids, how it affects hybrid fitness, and whether it is a direct cause or consequence of speciation.
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Affiliation(s)
- Anne-Marie Dion-Côté
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, United States
| | - Daniel A Barbash
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, United States.
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17
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Comparative proteome analysis between C . briggsae embryos and larvae reveals a role of chromatin modification proteins in embryonic cell division. Sci Rep 2017; 7:4296. [PMID: 28655887 PMCID: PMC5487359 DOI: 10.1038/s41598-017-04533-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 05/16/2017] [Indexed: 11/12/2022] Open
Abstract
Caenorhabditis briggsae has emerged as a model for comparative biology against model organism C. elegans. Most of its cell fate specifications are completed during embryogenesis whereas its cell growth is achieved mainly in larval stages. The molecular mechanism underlying the drastic developmental changes is poorly understood. To gain insights into the molecular changes between the two stages, we compared the proteomes between the two stages using iTRAQ. We identified a total of 2,791 proteins in the C. briggsae embryos and larvae, 247 of which undergo up- or down-regulation between the two stages. The proteins that are upregulated in the larval stages are enriched in the Gene Ontology categories of energy production, protein translation, and cytoskeleton; whereas those upregulated in the embryonic stage are enriched in the categories of chromatin dynamics and posttranslational modification, suggesting a more active chromatin modification in the embryos than in the larva. Perturbation of a subset of chromatin modifiers followed by cell lineage analysis suggests their roles in controlling cell division pace. Taken together, we demonstrate a general molecular switch from chromatin modification to metabolism during the transition from C. briggsae embryonic to its larval stages using iTRAQ approach. The switch might be conserved across metazoans.
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Revisiting Suppression of Interspecies Hybrid Male Lethality in Caenorhabditis Nematodes. G3-GENES GENOMES GENETICS 2017; 7:1211-1214. [PMID: 28209763 PMCID: PMC5386869 DOI: 10.1534/g3.117.039479] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Within the nematode genus Caenorhabditis, Caenorhabditis briggsae and C. nigoni are among the most closely related species known. They differ in sexual mode, with C. nigoni retaining the ancestral XO male-XX female outcrossing system, while C. briggsae recently evolved self-fertility and an XX-biased sex ratio. Wild-type C. briggsae and C. nigoni can produce fertile hybrid XX female progeny, but XO progeny are either 100% inviable (when C. briggsae is the mother) or viable but sterile (when C. nigoni is the mother). A recent study provided evidence suggesting that loss of the Cbr-him-8 meiotic regulator in C. briggsae hermaphrodites allowed them to produce viable and fertile hybrid XO male progeny when mated to C. nigoni Because such males would be useful for a variety of genetic experiments, we sought to verify this result. Preliminary crosses with wild-type C. briggsae hermaphrodites occasionally produced fertile males, but they could not be confirmed to be interspecies hybrids. Using an RNA interference (RNAi) protocol that eliminates any possibility of self-progeny in Cbr-him-8 hermaphrodites, we found sterile males bearing the C. nigoni X chromosome, but no fertile males bearing the C. briggsae X, as in wild-type crosses. Our results suggest that the apparent rescue of XO hybrid viability and fertility is due to incomplete purging of self-sperm prior to mating.
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