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Laufer BI, Hwang H, Jianu JM, Mordaunt CE, Korf IF, Hertz-Picciotto I, LaSalle JM. Low-pass whole genome bisulfite sequencing of neonatal dried blood spots identifies a role for RUNX1 in Down syndrome DNA methylation profiles. Hum Mol Genet 2020; 29:3465-3476. [PMID: 33001180 PMCID: PMC7788293 DOI: 10.1093/hmg/ddaa218] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/16/2020] [Accepted: 09/25/2020] [Indexed: 12/17/2022] Open
Abstract
Neonatal dried blood spots (NDBS) are a widely banked sample source that enables retrospective investigation into early life molecular events. Here, we performed low-pass whole genome bisulfite sequencing (WGBS) of 86 NDBS DNA to examine early life Down syndrome (DS) DNA methylation profiles. DS represents an example of genetics shaping epigenetics, as multiple array-based studies have demonstrated that trisomy 21 is characterized by genome-wide alterations to DNA methylation. By assaying over 24 million CpG sites, thousands of genome-wide significant (q < 0.05) differentially methylated regions (DMRs) that distinguished DS from typical development and idiopathic developmental delay were identified. Machine learning feature selection refined these DMRs to 22 loci. The DS DMRs mapped to genes involved in neurodevelopment, metabolism, and transcriptional regulation. Based on comparisons with previous DS methylation studies and reference epigenomes, the hypermethylated DS DMRs were significantly (q < 0.05) enriched across tissues while the hypomethylated DS DMRs were significantly (q < 0.05) enriched for blood-specific chromatin states. A ~28 kb block of hypermethylation was observed on chromosome 21 in the RUNX1 locus, which encodes a hematopoietic transcription factor whose binding motif was the most significantly enriched (q < 0.05) overall and specifically within the hypomethylated DMRs. Finally, we also identified DMRs that distinguished DS NDBS based on the presence or absence of congenital heart disease (CHD). Together, these results not only demonstrate the utility of low-pass WGBS on NDBS samples for epigenome-wide association studies, but also provide new insights into the early life mechanisms of epigenomic dysregulation resulting from trisomy 21.
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Affiliation(s)
- Benjamin I Laufer
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA 95616, USA.,Genome Center, University of California, Davis, CA 95616, USA.,MIND Institute, University of California, Davis, CA 95616, USA
| | - Hyeyeon Hwang
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA 95616, USA.,Genome Center, University of California, Davis, CA 95616, USA.,MIND Institute, University of California, Davis, CA 95616, USA
| | - Julia M Jianu
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA 95616, USA.,Genome Center, University of California, Davis, CA 95616, USA.,MIND Institute, University of California, Davis, CA 95616, USA
| | - Charles E Mordaunt
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA 95616, USA.,Genome Center, University of California, Davis, CA 95616, USA.,MIND Institute, University of California, Davis, CA 95616, USA
| | - Ian F Korf
- Genome Center, University of California, Davis, CA 95616, USA.,Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
| | - Irva Hertz-Picciotto
- MIND Institute, University of California, Davis, CA 95616, USA.,Department of Public Health Sciences, School of Medicine, University of California, Davis, CA 95616, USA
| | - Janine M LaSalle
- Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis, CA 95616, USA.,Genome Center, University of California, Davis, CA 95616, USA.,MIND Institute, University of California, Davis, CA 95616, USA
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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: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Vargas E, McNally K, Friedman JA, Cortes DB, Wang DY, Korf IF, McNally FJ. Autosomal Trisomy and Triploidy Are Corrected During Female Meiosis in Caenorhabditis elegans. Genetics 2017; 207:911-922. [PMID: 28882988 PMCID: PMC5676225 DOI: 10.1534/genetics.117.300259] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 09/05/2017] [Indexed: 11/18/2022] Open
Abstract
Trisomy and triploidy, defined as the presence of a third copy of one or all chromosomes, respectively, are deleterious in many species including humans. Previous studies have demonstrated that Caenorhabditis elegans with a third copy of the X chromosome are viable and fertile. However, the extra X chromosome was shown to preferentially segregate into the first polar body during oocyte meiosis to produce a higher frequency of euploid offspring than would be generated by random segregation. Here, we demonstrate that extra autosomes are preferentially eliminated by triploid C. elegans and trisomy IV C. elegans Live imaging of anaphase-lagging chromosomes and analysis of REC-8 staining of metaphase II spindles revealed that, in triploids, some univalent chromosomes do not lose cohesion and preferentially segregate intact into the first polar body during anaphase I, whereas other autosomes segregate chromatids equationally at anaphase I and eliminate some of the resulting single chromatids during anaphase II. We also demonstrate asymmetry in the anaphase spindle, which may contribute to the asymmetric segregation. This study reveals a pathway that allows aneuploid parents to produce euploid offspring at higher than random frequency.
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Affiliation(s)
- Elizabeth Vargas
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Karen McNally
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Jacob A Friedman
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Daniel B Cortes
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - David Y Wang
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Ian F Korf
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
| | - Francis J McNally
- Department of Molecular and Cellular Biology, University of California, Davis, California 95616
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Hartono SR, Korf IF, Chédin F. GC skew is a conserved property of unmethylated CpG island promoters across vertebrates. Nucleic Acids Res 2015; 43:9729-41. [PMID: 26253743 PMCID: PMC4787789 DOI: 10.1093/nar/gkv811] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 07/29/2015] [Indexed: 01/18/2023] Open
Abstract
GC skew is a measure of the strand asymmetry in the distribution of guanines and cytosines. GC skew favors R-loops, a type of three stranded nucleic acid structures that form upon annealing of an RNA strand to one strand of DNA, creating a persistent RNA:DNA hybrid. Previous studies show that GC skew is prevalent at thousands of human CpG island (CGI) promoters and transcription termination regions, which correspond to hotspots of R-loop formation. Here, we investigated the conservation of GC skew patterns in 60 sequenced chordates genomes. We report that GC skew is a conserved sequence characteristic of the CGI promoter class in vertebrates. Furthermore, we reveal that promoter GC skew peaks at the exon 1/ intron1 junction and that it is highly correlated with gene age and CGI promoter strength. Our data also show that GC skew is predictive of unmethylated CGI promoters in a range of vertebrate species and that it imparts significant DNA hypomethylation for promoters with intermediate CpG densities. Finally, we observed that terminal GC skew is conserved for a subset of vertebrate genes that tend to be located significantly closer to their downstream neighbors, consistent with a role for R-loop formation in transcription termination.
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Affiliation(s)
- Stella R Hartono
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA 95616, United States
| | - Ian F Korf
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA 95616, United States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, CA 95616, United States
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Beitel CW, Froenicke L, Lang JM, Korf IF, Michelmore RW, Eisen JA, Darling AE. Strain- and plasmid-level deconvolution of a synthetic metagenome by sequencing proximity ligation products. PeerJ 2014; 2:e415. [PMID: 24918035 PMCID: PMC4045339 DOI: 10.7717/peerj.415] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/15/2014] [Indexed: 12/13/2022] Open
Abstract
Metagenomics is a valuable tool for the study of microbial communities but has been limited by the difficulty of "binning" the resulting sequences into groups corresponding to the individual species and strains that constitute the community. Moreover, there are presently no methods to track the flow of mobile DNA elements such as plasmids through communities or to determine which of these are co-localized within the same cell. We address these limitations by applying Hi-C, a technology originally designed for the study of three-dimensional genome structure in eukaryotes, to measure the cellular co-localization of DNA sequences. We leveraged Hi-C data generated from a simple synthetic metagenome sample to accurately cluster metagenome assembly contigs into groups that contain nearly complete genomes of each species. The Hi-C data also reliably associated plasmids with the chromosomes of their host and with each other. We further demonstrated that Hi-C data provides a long-range signal of strain-specific genotypes, indicating such data may be useful for high-resolution genotyping of microbial populations. Our work demonstrates that Hi-C sequencing data provide valuable information for metagenome analyses that are not currently obtainable by other methods. This metagenomic Hi-C method could facilitate future studies of the fine-scale population structure of microbes, as well as studies of how antibiotic resistance plasmids (or other genetic elements) mobilize in microbial communities. The method is not limited to microbiology; the genetic architecture of other heterogeneous populations of cells could also be studied with this technique.
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Affiliation(s)
| | - Lutz Froenicke
- The University of California, Davis Genome Center , Davis, CA , USA
| | - Jenna M Lang
- The University of California, Davis Genome Center , Davis, CA , USA
| | - Ian F Korf
- The University of California, Davis Genome Center , Davis, CA , USA ; Department of Molecular and Cellular Biology, University of California , Davis, CA , USA
| | - Richard W Michelmore
- The University of California, Davis Genome Center , Davis, CA , USA ; Department of Molecular and Cellular Biology, University of California , Davis, CA , USA ; Department of Plant Sciences, University of California , Davis, CA , USA
| | - Jonathan A Eisen
- The University of California, Davis Genome Center , Davis, CA , USA ; Department of Medical Microbiology and Immunology, University of California , Davis, CA , USA ; Department of Evolution and Ecology, University of California , Davis, CA , USA
| | - Aaron E Darling
- ithree institute, University of Technology Sydney , Sydney, NSW , Australia
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Bradnam KR, Fass JN, Alexandrov A, Baranay P, Bechner M, Birol I, Boisvert S, Chapman JA, Chapuis G, Chikhi R, Chitsaz H, Chou WC, Corbeil J, Del Fabbro C, Docking TR, Durbin R, Earl D, Emrich S, Fedotov P, Fonseca NA, Ganapathy G, Gibbs RA, Gnerre S, Godzaridis E, Goldstein S, Haimel M, Hall G, Haussler D, Hiatt JB, Ho IY, Howard J, Hunt M, Jackman SD, Jaffe DB, Jarvis ED, Jiang H, Kazakov S, Kersey PJ, Kitzman JO, Knight JR, Koren S, Lam TW, Lavenier D, Laviolette F, Li Y, Li Z, Liu B, Liu Y, Luo R, Maccallum I, Macmanes MD, Maillet N, Melnikov S, Naquin D, Ning Z, Otto TD, Paten B, Paulo OS, Phillippy AM, Pina-Martins F, Place M, Przybylski D, Qin X, Qu C, Ribeiro FJ, Richards S, Rokhsar DS, Ruby JG, Scalabrin S, Schatz MC, Schwartz DC, Sergushichev A, Sharpe T, Shaw TI, Shendure J, Shi Y, Simpson JT, Song H, Tsarev F, Vezzi F, Vicedomini R, Vieira BM, Wang J, Worley KC, Yin S, Yiu SM, Yuan J, Zhang G, Zhang H, Zhou S, Korf IF. Assemblathon 2: evaluating de novo methods of genome assembly in three vertebrate species. Gigascience 2013; 2:10. [PMID: 23870653 PMCID: PMC3844414 DOI: 10.1186/2047-217x-2-10] [Citation(s) in RCA: 415] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 07/15/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The process of generating raw genome sequence data continues to become cheaper, faster, and more accurate. However, assembly of such data into high-quality, finished genome sequences remains challenging. Many genome assembly tools are available, but they differ greatly in terms of their performance (speed, scalability, hardware requirements, acceptance of newer read technologies) and in their final output (composition of assembled sequence). More importantly, it remains largely unclear how to best assess the quality of assembled genome sequences. The Assemblathon competitions are intended to assess current state-of-the-art methods in genome assembly. RESULTS In Assemblathon 2, we provided a variety of sequence data to be assembled for three vertebrate species (a bird, a fish, and snake). This resulted in a total of 43 submitted assemblies from 21 participating teams. We evaluated these assemblies using a combination of optical map data, Fosmid sequences, and several statistical methods. From over 100 different metrics, we chose ten key measures by which to assess the overall quality of the assemblies. CONCLUSIONS Many current genome assemblers produced useful assemblies, containing a significant representation of their genes and overall genome structure. However, the high degree of variability between the entries suggests that there is still much room for improvement in the field of genome assembly and that approaches which work well in assembling the genome of one species may not necessarily work well for another.
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Abstract
In most eukaryotes, the kinetochore protein complex assembles at a single locus termed the centromere to attach chromosomes to spindle microtubules. Holocentric chromosomes have the unusual property of attaching to spindle microtubules along their entire length. Our mechanistic understanding of holocentric chromosome function is derived largely from studies in the nematode Caenorhabditis elegans, but holocentric chromosomes are found over a broad range of animal and plant species. In this review, we describe how holocentricity may be identified through cytological and molecular methods. By surveying the diversity of organisms with holocentric chromosomes, we estimate that the trait has arisen at least 13 independent times (four times in plants and at least nine times in animals). Holocentric chromosomes have inherent problems in meiosis because bivalents can attach to spindles in a random fashion. Interestingly, there are several solutions that have evolved to allow accurate meiotic segregation of holocentric chromosomes. Lastly, we describe how extensive genome sequencing and experiments in nonmodel organisms may allow holocentric chromosomes to shed light on general principles of chromosome segregation.
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Affiliation(s)
- Daniël P Melters
- Department of Molecular and Cell Biology and Genome Center, University of California, Davis, CA, USA
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Bedell JA, Budiman MA, Nunberg A, Citek RW, Robbins D, Jones J, Flick E, Rholfing T, Fries J, Bradford K, McMenamy J, Smith M, Holeman H, Roe BA, Wiley G, Korf IF, Rabinowicz PD, Lakey N, McCombie WR, Jeddeloh JA, Martienssen RA. Sorghum genome sequencing by methylation filtration. PLoS Biol 2005; 3:e13. [PMID: 15660154 PMCID: PMC539327 DOI: 10.1371/journal.pbio.0030013] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 11/08/2004] [Indexed: 11/19/2022] Open
Abstract
Sorghum bicolor is a close relative of maize and is a staple crop in Africa and much of the developing world because of its superior tolerance of arid growth conditions. We have generated sequence from the hypomethylated portion of the sorghum genome by applying methylation filtration (MF) technology. The evidence suggests that 96% of the genes have been sequence tagged, with an average coverage of 65% across their length. Remarkably, this level of gene discovery was accomplished after generating a raw coverage of less than 300 megabases of the 735-megabase genome. MF preferentially captures exons and introns, promoters, microRNAs, and simple sequence repeats, and minimizes interspersed repeats, thus providing a robust view of the functional parts of the genome. The sorghum MF sequence set is beneficial to research on sorghum and is also a powerful resource for comparative genomics among the grasses and across the entire plant kingdom. Thousands of hypothetical gene predictions in rice and Arabidopsis are supported by the sorghum dataset, and genomic similarities highlight evolutionarily conserved regions that will lead to a better understanding of rice and Arabidopsis.
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Affiliation(s)
- Joseph A Bedell
- Bioinformatics, Orion Genomics Saint Louis, Missouri United States of America.
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