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Ray M, Conard AM, Urban J, Mahableshwarkar P, Aguilera J, Huang A, Vaidyanathan S, Larschan E. Sex-specific splicing occurs genome-wide during early Drosophila embryogenesis. eLife 2023; 12:e87865. [PMID: 37466240 PMCID: PMC10400075 DOI: 10.7554/elife.87865] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/11/2023] [Indexed: 07/20/2023] Open
Abstract
Sex-specific splicing is an essential process that regulates sex determination and drives sexual dimorphism. Yet, how early in development widespread sex-specific transcript diversity occurs was unknown because it had yet to be studied at the genome-wide level. We use the powerful Drosophila model to show that widespread sex-specific transcript diversity occurs early in development, concurrent with zygotic genome activation. We also present a new pipeline called time2Splice to quantify changes in alternative splicing over time. Furthermore, we determine that one of the consequences of losing an essential maternally deposited pioneer factor called CLAMP (chromatin-linked adapter for MSL proteins) is altered sex-specific splicing of genes involved in diverse biological processes that drive development. Overall, we show that sex-specific differences in transcript diversity exist even at the earliest stages of development..
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Affiliation(s)
- Mukulika Ray
- MCB department, Brown UniversityProvidenceUnited States
| | | | - Jennifer Urban
- Biology department, Johns Hopkins UniversityBaltimoreUnited States
| | - Pranav Mahableshwarkar
- MCB department, Brown UniversityProvidenceUnited States
- CCMB department, Brown UniversityProvidenceUnited States
| | | | - Annie Huang
- MCB department, Brown UniversityProvidenceUnited States
| | - Smriti Vaidyanathan
- MCB department, Brown UniversityProvidenceUnited States
- CCMB department, Brown UniversityProvidenceUnited States
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3
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Extended intergenic DNA contributes to neuron-specific expression of neighboring genes in the mammalian nervous system. Nat Commun 2022; 13:2733. [PMID: 35585070 PMCID: PMC9117226 DOI: 10.1038/s41467-022-30192-z] [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: 08/14/2020] [Accepted: 04/20/2022] [Indexed: 11/08/2022] Open
Abstract
Mammalian genomes comprise largely intergenic noncoding DNA with numerous cis-regulatory elements. Whether and how the size of intergenic DNA affects gene expression in a tissue-specific manner remain unknown. Here we show that genes with extended intergenic regions are preferentially expressed in neural tissues but repressed in other tissues in mice and humans. Extended intergenic regions contain twice as many active enhancers in neural tissues compared to other tissues. Neural genes with extended intergenic regions are globally co-expressed with neighboring neural genes controlled by distinct enhancers in the shared intergenic regions. Moreover, generic neural genes expressed in multiple tissues have significantly longer intergenic regions than neural genes expressed in fewer tissues. The intergenic regions of the generic neural genes have many tissue-specific active enhancers containing distinct transcription factor binding sites specific to each neural tissue. We also show that genes with extended intergenic regions are enriched for neural genes only in vertebrates. The expansion of intergenic regions may reflect the regulatory complexity of tissue-type-specific gene expression in the nervous system.
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Foe VE. Does the Pachytene Checkpoint, a Feature of Meiosis, Filter Out Mistakes in Double-Strand DNA Break Repair and as a side-Effect Strongly Promote Adaptive Speciation? Integr Org Biol 2022; 4:obac008. [PMID: 36827645 PMCID: PMC8998493 DOI: 10.1093/iob/obac008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This essay aims to explain two biological puzzles: why eukaryotic transcription units are composed of short segments of coding DNA interspersed with long stretches of non-coding (intron) DNA, and the near ubiquity of sexual reproduction. As is well known, alternative splicing of its coding sequences enables one transcription unit to produce multiple variants of each encoded protein. Additionally, padding transcription units with non-coding DNA (often many thousands of base pairs long) provides a readily evolvable way to set how soon in a cell cycle the various mRNAs will begin being expressed and the total amount of mRNA that each transcription unit can make during a cell cycle. This regulation complements control via the transcriptional promoter and facilitates the creation of complex eukaryotic cell types, tissues, and organisms. However, it also makes eukaryotes exceedingly vulnerable to double-strand DNA breaks, which end-joining break repair pathways can repair incorrectly. Transcription units cover such a large fraction of the genome that any mis-repair producing a reorganized chromosome has a high probability of destroying a gene. During meiosis, the synaptonemal complex aligns homologous chromosome pairs and the pachytene checkpoint detects, selectively arrests, and in many organisms actively destroys gamete-producing cells with chromosomes that cannot adequately synapse; this creates a filter favoring transmission to the next generation of chromosomes that retain the parental organization, while selectively culling those with interrupted transcription units. This same meiotic checkpoint, reacting to accidental chromosomal reorganizations inflicted by error-prone break repair, can, as a side effect, provide a mechanism for the formation of new species in sympatry. It has been a long-standing puzzle how something as seemingly maladaptive as hybrid sterility between such new species can arise. I suggest that this paradox is resolved by understanding the adaptive importance of the pachytene checkpoint, as outlined above.
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Xu Q, Niu SC, Li KL, Zheng PJ, Zhang XJ, Jia Y, Liu Y, Niu YX, Yu LH, Chen DF, Zhang GQ. Chromosome-Scale Assembly of the Dendrobium nobile Genome Provides Insights Into the Molecular Mechanism of the Biosynthesis of the Medicinal Active Ingredient of Dendrobium. Front Genet 2022; 13:844622. [PMID: 35299950 PMCID: PMC8921531 DOI: 10.3389/fgene.2022.844622] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/11/2022] [Indexed: 01/07/2023] Open
Abstract
Orchids constitute approximately 10% of flowering plant species. However, only about 10 orchid genomes have been published. Metabolites are the main way through which orchids respond to their environment. Dendrobium nobile, belonging to Dendrobium, the second largest genus in Orchidaceae, has high ornamental, medicinal, and ecological value. D. nobile is the source of many popular horticultural varieties. Among the Dendrobium species, D. nobile has the highest amount of dendrobine, which is regarded as one of the criteria for evaluating medicinal quality. Due to lack of data and analysis at the genomic level, the biosynthesis pathways of dendrobine and other related medicinal ingredients in D. nobile are unknown. In this paper, we report a chromosome-scale reference genome of D. nobile to facilitate the investigation of its genomic characteristics for comparison with other Dendrobium species. The assembled genome size of D. nobile was 1.19 Gb. Of the sequences, 99.45% were anchored to 19 chromosomes. Furthermore, we identified differences in gene number and gene expression patterns compared with two other Dendrobium species by integrating whole-genome sequencing and transcriptomic analysis [e.g., genes in the polysaccharide biosynthesis pathway and upstream of the alkaloid (dendrobine) biosynthesis pathway]. Differences in the TPS and CYP450 gene families were also found among orchid species. All the above differences might contribute to the species-specific medicinal ingredient biosynthesis pathways. The metabolic pathway-related analysis will provide further insight into orchid responses to the environment. Additionally, the reference genome will provide important insights for further molecular elucidation of the medicinal active ingredients of Dendrobium and enhance the understanding of orchid evolution.
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Affiliation(s)
- Qing Xu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
- *Correspondence: Qing Xu, ; Duan-Fen Chen, ; Guo-Qiang Zhang,
| | - Shan-Ce Niu
- College of Horticulture, Hebei Agricultural University, Baoding, China
- State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding, China
| | - Kang-Li Li
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Pei-Ji Zheng
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Xiao-Jing Zhang
- College of Horticulture, Hebei Agricultural University, Baoding, China
| | - Yin Jia
- College of Horticulture, Hebei Agricultural University, Baoding, China
| | - Yang Liu
- College of Horticulture, Hebei Agricultural University, Baoding, China
| | - Yun-Xia Niu
- School of Vocational Education, Tianjin University of Technology and Education, Tianjin, China
| | - Li-Hong Yu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Duan-Fen Chen
- College of Horticulture, Hebei Agricultural University, Baoding, China
- *Correspondence: Qing Xu, ; Duan-Fen Chen, ; Guo-Qiang Zhang,
| | - Guo-Qiang Zhang
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
- Laboratory for Orchid Conservation and Utilization, The Orchid Conservation and Research Center of Shenzhen, The National Orchid Conservation Center of China, Shenzhen, China
- *Correspondence: Qing Xu, ; Duan-Fen Chen, ; Guo-Qiang Zhang,
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Prudêncio P, Savisaar R, Rebelo K, Martinho RG, Carmo-Fonseca M. Transcription and splicing dynamics during early Drosophila development. RNA (NEW YORK, N.Y.) 2022; 28:139-161. [PMID: 34667107 PMCID: PMC8906543 DOI: 10.1261/rna.078933.121] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/23/2021] [Indexed: 05/03/2023]
Abstract
Widespread cotranscriptional splicing has been demonstrated from yeast to human. However, most studies to date addressing the kinetics of splicing relative to transcription used either Saccharomyces cerevisiae or metazoan cultured cell lines. Here, we adapted native elongating transcript sequencing technology (NET-seq) to measure cotranscriptional splicing dynamics during the early developmental stages of Drosophila melanogaster embryos. Our results reveal the position of RNA polymerase II (Pol II) when both canonical and recursive splicing occur. We found heterogeneity in splicing dynamics, with some RNAs spliced immediately after intron transcription, whereas for other transcripts no splicing was observed over the first 100 nt of the downstream exon. Introns that show splicing completion before Pol II has reached the end of the downstream exon are necessarily intron-defined. We studied the splicing dynamics of both nascent pre-mRNAs transcribed in the early embryo, which have few and short introns, as well as pre-mRNAs transcribed later in embryonic development, which contain multiple long introns. As expected, we found a relationship between the proportion of spliced reads and intron size. However, intron definition was observed at all intron sizes. We further observed that genes transcribed in the early embryo tend to be isolated in the genome whereas genes transcribed later are often overlapped by a neighboring convergent gene. In isolated genes, transcription termination occurred soon after the polyadenylation site, while in overlapped genes, Pol II persisted associated with the DNA template after cleavage and polyadenylation of the nascent transcript. Taken together, our data unravel novel dynamic features of Pol II transcription and splicing in the developing Drosophila embryo.
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Affiliation(s)
- Pedro Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Algarve Biomedical Center Research Institute (ABC-RI), Universidade do Algarve, 8005-139 Faro, Portugal
| | - Rosina Savisaar
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Kenny Rebelo
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Rui Gonçalo Martinho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
- Algarve Biomedical Center Research Institute (ABC-RI), Universidade do Algarve, 8005-139 Faro, Portugal
- Department of Medical Sciences and Institute for Biomedicine (iBiMED), Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Maria Carmo-Fonseca
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
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Cotsworth S, Jackson CJ, Hallson G, Fitzpatrick KA, Syrzycka M, Coulthard AB, Bejsovec A, Marchetti M, Pimpinelli S, Wang SJH, Camfield RG, Verheyen EM, Sinclair DA, Honda BM, Hilliker AJ. Characterization of Gfat1 (zeppelin) and Gfat2, Essential Paralogous Genes Which Encode the Enzymes That Catalyze the Rate-Limiting Step in the Hexosamine Biosynthetic Pathway in Drosophila melanogaster. Cells 2022; 11:cells11030448. [PMID: 35159258 PMCID: PMC8834284 DOI: 10.3390/cells11030448] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/21/2022] [Accepted: 01/22/2022] [Indexed: 11/16/2022] Open
Abstract
The zeppelin (zep) locus is known for its essential role in the development of the embryonic cuticle of Drosophila melanogaster. We show here that zep encodes Gfat1 (Glutamine: Fructose-6-Phosphate Aminotransferase 1; CG12449), the enzyme that catalyzes the rate-limiting step in the hexosamine biosynthesis pathway (HBP). This conserved pathway diverts 2%–5% of cellular glucose from glycolysis and is a nexus of sugar (fructose-6-phosphate), amino acid (glutamine), fatty acid [acetyl-coenzymeA (CoA)], and nucleotide/energy (UDP) metabolism. We also describe the isolation and characterization of lethal mutants in the euchromatic paralog, Gfat2 (CG1345), and demonstrate that ubiquitous expression of Gfat1+ or Gfat2+ transgenes can rescue lethal mutations in either gene. Gfat1 and Gfat2 show differences in mRNA and protein expression during embryogenesis and in essential tissue-specific requirements for Gfat1 and Gfat2, suggesting a degree of functional evolutionary divergence. An evolutionary, cytogenetic analysis of the two genes in six Drosophila species revealed Gfat2 to be located within euchromatin in all six species. Gfat1 localizes to heterochromatin in three melanogaster-group species, and to euchromatin in the more distantly related species. We have also found that the pattern of flanking-gene microsynteny is highly conserved for Gfat1 and somewhat less conserved for Gfat2.
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Affiliation(s)
- Shawn Cotsworth
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Catherine J. Jackson
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
- Department of Plastic and Reconstructive Surgery, Institute for Surgical Research, University of Oslo, N-0424 Oslo, Norway
- The Department of Medical Biochemistry, Oslo University Hospital, N-0424 Oslo, Norway
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, N-0424 Oslo, Norway
| | - Graham Hallson
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Kathleen A. Fitzpatrick
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Monika Syrzycka
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
- Allergan Canada, 500-85 Enterprise Blvd, Markham, ON L6G 0B5, Canada
| | | | - Amy Bejsovec
- Department of Biology, Duke University, Durham, NC 27708, USA;
| | - Marcella Marchetti
- Department of Biology and Biotechnology “C. Darwin”, “Sapienza” University of Rome, 00185 Rome, Italy; (M.M.); (S.P.)
| | - Sergio Pimpinelli
- Department of Biology and Biotechnology “C. Darwin”, “Sapienza” University of Rome, 00185 Rome, Italy; (M.M.); (S.P.)
| | - Simon J. H. Wang
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Robert G. Camfield
- BC Genome Science Centre, 675 West 10th Avenue, Vancouver, BC V5Z 1L3, Canada;
| | - Esther M. Verheyen
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Donald A. Sinclair
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Barry M. Honda
- Department of Molecular Biology and Biochemistry (MBB), Simon Fraser University, 8888 University Dr., Burnaby, BC V5A 1S6, Canada; (S.C.); (C.J.J.); (G.H.); (K.A.F.); (M.S.); (S.J.H.W.); (E.M.V.); (D.A.S.); (B.M.H.)
| | - Arthur J. Hilliker
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada;
- Correspondence:
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Carmon S, Jonas F, Barkai N, Schejter ED, Shilo BZ. Generation and timing of graded responses to morphogen gradients. Development 2021; 148:273784. [PMID: 34918740 PMCID: PMC8722393 DOI: 10.1242/dev.199991] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/17/2021] [Indexed: 11/20/2022]
Abstract
Morphogen gradients are known to subdivide a naive cell field into distinct zones of gene expression. Here, we examine whether morphogens can also induce a graded response within such domains. To this end, we explore the role of the Dorsal protein nuclear gradient along the dorsoventral axis in defining the graded pattern of actomyosin constriction that initiates gastrulation in early Drosophila embryos. Two complementary mechanisms for graded accumulation of mRNAs of crucial zygotic Dorsal target genes were identified. First, activation of target-gene expression expands over time from the ventral-most region of high nuclear Dorsal to lateral regions, where the levels are lower, as a result of a Dorsal-dependent activation probability of transcription sites. Thus, sites that are activated earlier will exhibit more mRNA accumulation. Second, once the sites are activated, the rate of RNA Polymerase II loading is also dependent on Dorsal levels. Morphological restrictions require that translation of the graded mRNA be delayed until completion of embryonic cell formation. Such timing is achieved by large introns, which provide a delay in production of the mature mRNAs. Spatio-temporal regulation of key zygotic genes therefore shapes the pattern of gastrulation.
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Affiliation(s)
- Shari Carmon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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9
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Zhang Y, Zhang GQ, Zhang D, Liu XD, Xu XY, Sun WH, Yu X, Zhu X, Wang ZW, Zhao X, Zhong WY, Chen H, Yin WL, Huang T, Niu SC, Liu ZJ. Chromosome-scale assembly of the Dendrobium chrysotoxum genome enhances the understanding of orchid evolution. HORTICULTURE RESEARCH 2021; 8:183. [PMID: 34465765 PMCID: PMC8408244 DOI: 10.1038/s41438-021-00621-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/23/2021] [Accepted: 06/01/2021] [Indexed: 05/03/2023]
Abstract
As one of the largest families of angiosperms, the Orchidaceae family is diverse. Dendrobium represents the second largest genus of the Orchidaceae. However, an assembled high-quality genome of species in this genus is lacking. Here, we report a chromosome-scale reference genome of Dendrobium chrysotoxum, an important ornamental and medicinal orchid species. The assembled genome size of D. chrysotoxum was 1.37 Gb, with a contig N50 value of 1.54 Mb. Of the sequences, 95.75% were anchored to 19 pseudochromosomes. There were 30,044 genes predicted in the D. chrysotoxum genome. Two whole-genome polyploidization events occurred in D. chrysotoxum. In terms of the second event, whole-genome duplication (WGD) was also found to have occurred in other Orchidaceae members, which diverged mainly via gene loss immediately after the WGD event occurred; the first duplication was found to have occurred in most monocots (tau event). We identified sugar transporter (SWEET) gene family expansion, which might be related to the abundant medicinal compounds and fleshy stems of D. chrysotoxum. MADS-box genes were identified in D. chrysotoxum, as well as members of TPS and Hsp90 gene families, which are associated with resistance, which may contribute to the adaptive evolution of orchids. We also investigated the interplay among carotenoid, ABA, and ethylene biosynthesis in D. chrysotoxum to elucidate the regulatory mechanisms of the short flowering period of orchids with yellow flowers. The reference D. chrysotoxum genome will provide important insights for further research on medicinal active ingredients and breeding and enhances the understanding of orchid evolution.
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Affiliation(s)
- Yongxia Zhang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518071, China
| | - Guo-Qiang Zhang
- Laboratory for Orchid Conservation and Utilization, Orchid Conservation and Research Center, The National Orchid Conservation Center, Shenzhen, 518114, China
- School of Food Science and Technology, Foshan University, Foshan, 528225, China
| | - Diyang Zhang
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xue-Die Liu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xin-Yu Xu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Wei-Hong Sun
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xia Yu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiaoen Zhu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518071, China
| | | | | | | | - Hongfeng Chen
- Key Laboratory of Plant Resources Conservation Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Wei-Lun Yin
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, 100083, China
| | - Tengbo Huang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518071, China.
| | - Shan-Ce Niu
- College of Horticulture, Hebei Agricultural University, Baoding, 071000, China.
| | - Zhong-Jian Liu
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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10
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Abou Chakra M, Isserlin R, Tran TN, Bader GD. Control of tissue development and cell diversity by cell cycle-dependent transcriptional filtering. eLife 2021; 10:64951. [PMID: 34212855 PMCID: PMC8279763 DOI: 10.7554/elife.64951] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 07/01/2021] [Indexed: 12/12/2022] Open
Abstract
Cell cycle duration changes dramatically during development, starting out fast to generate cells quickly and slowing down over time as the organism matures. The cell cycle can also act as a transcriptional filter to control the expression of long gene transcripts, which are partially transcribed in short cycles. Using mathematical simulations of cell proliferation, we identify an emergent property that this filter can act as a tuning knob to control gene transcript expression, cell diversity, and the number and proportion of different cell types in a tissue. Our predictions are supported by comparison to single-cell RNA-seq data captured over embryonic development. Additionally, evolutionary genome analysis shows that fast-developing organisms have a narrow genomic distribution of gene lengths while slower developers have an expanded number of long genes. Our results support the idea that cell cycle dynamics may be important across multicellular animals for controlling gene transcript expression and cell fate.
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Affiliation(s)
| | - Ruth Isserlin
- The Donnelly Centre, University of Toronto, Toronto, Canada
| | - Thinh N Tran
- The Donnelly Centre, University of Toronto, Toronto, Canada
| | - Gary D Bader
- The Donnelly Centre, University of Toronto, Toronto, Canada
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11
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Evolutionary Dynamics of the Pericentromeric Heterochromatin in Drosophila virilis and Related Species. Genes (Basel) 2021; 12:genes12020175. [PMID: 33513919 PMCID: PMC7911463 DOI: 10.3390/genes12020175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/21/2021] [Accepted: 01/23/2021] [Indexed: 12/19/2022] Open
Abstract
Pericentromeric heterochromatin in Drosophila generally consists of repetitive DNA, forming the environment associated with gene silencing. Despite the expanding knowledge of the impact of transposable elements (TEs) on the host genome, little is known about the evolution of pericentromeric heterochromatin, its structural composition, and age. During the evolution of the Drosophilidae, hundreds of genes have become embedded within pericentromeric regions yet retained activity. We investigated a pericentromeric heterochromatin fragment found in D. virilis and related species, describing the evolution of genes in this region and the age of TE invasion. Regardless of the heterochromatic environment, the amino acid composition of the genes is under purifying selection. However, the selective pressure affects parts of genes in varying degrees, resulting in expansion of gene introns due to TEs invasion. According to the divergence of TEs, the pericentromeric heterochromatin of the species of virilis group began to form more than 20 million years ago by invasions of retroelements, miniature inverted repeat transposable elements (MITEs), and Helitrons. Importantly, invasions into the heterochromatin continue to occur by TEs that fall under the scope of piRNA silencing. Thus, the pericentromeric heterochromatin, in spite of its ability to induce silencing, has the means for being dynamic, incorporating the regions of active transcription.
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12
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Sessions SK, Wake DB. Forever young: Linking regeneration and genome size in salamanders. Dev Dyn 2020; 250:768-778. [DOI: 10.1002/dvdy.279] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/21/2020] [Accepted: 11/11/2020] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - David B. Wake
- Department of Integrative Biology and Museum of Vertebrate Zoology University of California Berkeley California USA
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13
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Nakamura M, Verboon JM, Allen TE, Abreu-Blanco MT, Liu R, Dominguez ANM, Delrow JJ, Parkhurst SM. Autocrine insulin pathway signaling regulates actin dynamics in cell wound repair. PLoS Genet 2020; 16:e1009186. [PMID: 33306674 PMCID: PMC7758051 DOI: 10.1371/journal.pgen.1009186] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 12/23/2020] [Accepted: 10/09/2020] [Indexed: 01/13/2023] Open
Abstract
Cells are exposed to frequent mechanical and/or chemical stressors that can compromise the integrity of the plasma membrane and underlying cortical cytoskeleton. The molecular mechanisms driving the immediate repair response launched to restore the cell cortex and circumvent cell death are largely unknown. Using microarrays and drug-inhibition studies to assess gene expression, we find that initiation of cell wound repair in the Drosophila model is dependent on translation, whereas transcription is required for subsequent steps. We identified 253 genes whose expression is up-regulated (80) or down-regulated (173) in response to laser wounding. A subset of these genes were validated using RNAi knockdowns and exhibit aberrant actomyosin ring assembly and/or actin remodeling defects. Strikingly, we find that the canonical insulin signaling pathway controls actin dynamics through the actin regulators Girdin and Chickadee (profilin), and its disruption leads to abnormal wound repair. Our results provide new insight for understanding how cell wound repair proceeds in healthy individuals and those with diseases involving wound healing deficiencies.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Jeffrey M. Verboon
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Tessa E. Allen
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Maria Teresa Abreu-Blanco
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Raymond Liu
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Andrew N. M. Dominguez
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Jeffrey J. Delrow
- Genomics Shared Resource, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Susan M. Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
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14
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Catalogue of stage-specific transcripts in Ixodes ricinus and their potential functions during the tick life-cycle. Parasit Vectors 2020; 13:311. [PMID: 32546252 PMCID: PMC7296661 DOI: 10.1186/s13071-020-04173-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 06/05/2020] [Indexed: 12/15/2022] Open
Abstract
Background The castor bean tick Ixodes ricinus is an important vector of several clinically important diseases, whose prevalence increases with accelerating global climate changes. Characterization of a tick life-cycle is thus of great importance. However, researchers mainly focus on specific organs of fed life stages, while early development of this tick species is largely neglected. Methods In an attempt to better understand the life-cycle of this widespread arthropod parasite, we sequenced the transcriptomes of four life stages (egg, larva, nymph and adult female), including unfed and partially blood-fed individuals. To enable a more reliable identification of transcripts and their comparison in all five transcriptome libraries, we validated an improved-fit set of five I. ricinus-specific reference genes for internal standard normalization of our transcriptomes. Then, we mapped biological functions to transcripts identified in different life stages (clusters) to elucidate life stage-specific processes. Finally, we drew conclusions from the functional enrichment of these clusters specifically assigned to each transcriptome, also in the context of recently published transcriptomic studies in ticks. Results We found that reproduction-related transcripts are present in both fed nymphs and fed females, underlining the poorly documented importance of ovaries as moulting regulators in ticks. Additionally, we identified transposase transcripts in tick eggs suggesting elevated transposition during embryogenesis, co-activated with factors driving developmental regulation of gene expression. Our findings also highlight the importance of the regulation of energetic metabolism in tick eggs during embryonic development and glutamate metabolism in nymphs. Conclusions Our study presents novel insights into stage-specific transcriptomes of I. ricinus and extends the current knowledge of this medically important pathogen, especially in the early phases of its development.![]()
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15
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Singh R, Sophiarani Y. A report on DNA sequence determinants in gene expression. Bioinformation 2020; 16:422-431. [PMID: 32831525 PMCID: PMC7434957 DOI: 10.6026/97320630016422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 11/26/2022] Open
Abstract
The biased usage of nucleotides in coding sequence and its correlation with gene expression has been observed in several studies. A complex set of interactions between genes and other components of the expression system determine the amount of proteins produced from coding sequences. It is known that the elongation rate of polypeptide chain is affected by both codon usage bias and specific amino acid compositional constraints. Therefore, it is of interest to review local DNA-sequence elements and other positional as well as combinatorial constraints that play significant role in gene expression.
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Affiliation(s)
- Ravail Singh
- Indian Institute of Integrative Medicine, CSIR, Canal Road, Jammu-180001
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16
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McCoy MJ, Fire AZ. Intron and gene size expansion during nervous system evolution. BMC Genomics 2020; 21:360. [PMID: 32410625 PMCID: PMC7222433 DOI: 10.1186/s12864-020-6760-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/28/2020] [Indexed: 01/07/2023] Open
Abstract
Background The evolutionary radiation of animals was accompanied by extensive expansion of gene and genome sizes, increased isoform diversity, and complexity of regulation. Results Here we show that the longest genes are enriched for expression in neuronal tissues of diverse vertebrates and of invertebrates. Additionally, we show that neuronal gene size expansion occurred predominantly through net gains in intron size, with a positional bias toward the 5′ end of each gene. Conclusions We find that intron and gene size expansion is a feature of many genes whose expression is enriched in nervous systems. We speculate that unique attributes of neurons may subject neuronal genes to evolutionary forces favoring net size expansion. This process could be associated with tissue-specific constraints on gene function and/or the evolution of increasingly complex gene regulation in nervous systems.
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Affiliation(s)
- Matthew J McCoy
- Grass Fellowship Program, Marine Biological Laboratory, Woods Hole, MA, 02543, USA. .,Departments of Pathology and Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Andrew Z Fire
- Departments of Pathology and Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
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17
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Kipryushina YO, Yakovlev KV. Maternal control of early patterning in sea urchin embryos. Differentiation 2020; 113:28-37. [PMID: 32371341 DOI: 10.1016/j.diff.2020.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 04/10/2020] [Accepted: 04/17/2020] [Indexed: 02/06/2023]
Abstract
Sea urchin development has been studied extensively for more than a century and considered regulative since the first experimental evidence. Further investigations have repeatedly supported this standpoint by revealing the presence of inductive mechanisms that alter cell fate decisions at early cleavage stages and flexibility of development in response to environmental conditions. Some features indicate that sea urchin development is not completely regulative, but actually includes determinative events. In 16-cell embryos, mesomeres and macromeres represent multipotency, while the cell fate of most vegetal micromeres is restricted. It is known that the mature sea urchin eggs are polarized by the asymmetrical distribution of some maternal mRNAs and proteins. Spatially-distributed maternal factors are necessary for the orientation of the primary animal-vegetal axis, which is established by both maternal and zygotic mechanisms later in development. The secondary dorsal-ventral axis is conditionally specified later in development. Dorsal-ventral polarity is very liable during the early cleavages, though more recent data argue that its direction may be oriented by maternal asymmetry. In this review, we focus on the role of maternal factors in initial embryonic patterning during the first cleavages of sea urchin embryos before activation of the embryonic genome.
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Affiliation(s)
- Yulia O Kipryushina
- Laboratory of Cytotechnology, National Scientific Center of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, Palchevsky St. 17, 690041, Vladivostok, Russia
| | - Konstantin V Yakovlev
- Laboratory of Cytotechnology, National Scientific Center of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, Palchevsky St. 17, 690041, Vladivostok, Russia; Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
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18
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The conserved regulatory basis of mRNA contributions to the early Drosophila embryo differs between the maternal and zygotic genomes. PLoS Genet 2020; 16:e1008645. [PMID: 32226006 PMCID: PMC7145188 DOI: 10.1371/journal.pgen.1008645] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 04/09/2020] [Accepted: 02/03/2020] [Indexed: 02/06/2023] Open
Abstract
The gene products that drive early development are critical for setting up developmental trajectories in all animals. The earliest stages of development are fueled by maternally provided mRNAs until the zygote can take over transcription of its own genome. In early development, both maternally deposited and zygotically transcribed gene products have been well characterized in model systems. Previously, we demonstrated that across the genus Drosophila, maternal and zygotic mRNAs are largely conserved but also showed a surprising amount of change across species, with more differences evolving at the zygotic stage than the maternal stage. In this study, we use comparative methods to elucidate the regulatory mechanisms underlying maternal deposition and zygotic transcription across species. Through motif analysis, we discovered considerable conservation of regulatory mechanisms associated with maternal transcription, as compared to zygotic transcription. We also found that the regulatory mechanisms active in the maternal and zygotic genomes are quite different. For maternally deposited genes, we uncovered many signals that are consistent with transcriptional regulation at the level of chromatin state through factors enriched in the ovary, rather than precisely controlled gene-specific factors. For genes expressed only by the zygotic genome, we found evidence for previously identified regulators such as Zelda and GAGA-factor, with multiple analyses pointing toward gene-specific regulation. The observed mechanisms of regulation are consistent with what is known about regulation in these two genomes: during oogenesis, the maternal genome is optimized to quickly produce a large volume of transcripts to provide to the oocyte; after zygotic genome activation, mechanisms are employed to activate transcription of specific genes in a spatiotemporally precise manner. Thus the genetic architecture of the maternal and zygotic genomes, and the specific requirements for the transcripts present at each stage of embryogenesis, determine the regulatory mechanisms responsible for transcripts present at these stages.
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19
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Zhou X, Zhang Y, Michal JJ, Qu L, Zhang S, Wildung MR, Du W, Pouchnik DJ, Zhao H, Xia Y, Shi H, Ji G, Davis JF, Smith GD, Griswold MD, Harland RM, Jiang Z. Alternative polyadenylation coordinates embryonic development, sexual dimorphism and longitudinal growth in Xenopus tropicalis. Cell Mol Life Sci 2019; 76:2185-2198. [PMID: 30729254 PMCID: PMC6597005 DOI: 10.1007/s00018-019-03036-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 01/09/2019] [Accepted: 01/30/2019] [Indexed: 12/27/2022]
Abstract
RNA alternative polyadenylation contributes to the complexity of information transfer from genome to phenome, thus amplifying gene function. Here, we report the first X. tropicalis resource with 127,914 alternative polyadenylation (APA) sites derived from embryos and adults. Overall, APA networks play central roles in coordinating the maternal-zygotic transition (MZT) in embryos, sexual dimorphism in adults and longitudinal growth from embryos to adults. APA sites coordinate reprogramming in embryos before the MZT, but developmental events after the MZT due to zygotic genome activation. The APA transcriptomes of young adults are more variable than growing adults and male frog APA transcriptomes are more divergent than females. The APA profiles of young females were similar to embryos before the MZT. Enriched pathways in developing embryos were distinct across the MZT and noticeably segregated from adults. Briefly, our results suggest that the minimal functional units in genomes are alternative transcripts as opposed to genes.
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Affiliation(s)
- Xiang Zhou
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA
- College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yangzi Zhang
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA
| | - Jennifer J Michal
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA
| | - Lujiang Qu
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA
- College of Animal Sciences and Technology, China Agricultural University, Beijing, China
| | - Shuwen Zhang
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA
| | - Mark R Wildung
- Laboratory for Biotechnology and Bioanalysis, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Weiwei Du
- Laboratory for Biotechnology and Bioanalysis, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Derek J Pouchnik
- Laboratory for Biotechnology and Bioanalysis, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Hui Zhao
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Yin Xia
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Honghua Shi
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
| | - Guoli Ji
- Department of Automation, Xiamen University, Xiamen, China
| | - Jon F Davis
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, USA
| | - Gary D Smith
- Departments of OB/GYN, Physiology, and Urology, University of Michigan, Ann Arbor, MI, USA
| | - Michael D Griswold
- Laboratory for Biotechnology and Bioanalysis, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Richard M Harland
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Zhihua Jiang
- Department of Animal Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA, 99164-7620, USA.
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20
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Sandler JE, Irizarry J, Stepanik V, Dunipace L, Amrhein H, Stathopoulos A. A Developmental Program Truncates Long Transcripts to Temporally Regulate Cell Signaling. Dev Cell 2019; 47:773-784.e6. [PMID: 30562515 DOI: 10.1016/j.devcel.2018.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/30/2018] [Accepted: 11/13/2018] [Indexed: 11/29/2022]
Abstract
Rapid mitotic divisions and a fixed transcription rate limit the maximal length of transcripts in early Drosophila embryos. Previous studies suggested that transcription of long genes is initiated but aborted, as early nuclear divisions have short interphases. Here, we identify long genes that are expressed during short nuclear cycles as truncated transcripts. The RNA binding protein Sex-lethal physically associates with transcripts for these genes and is required to support early termination to specify shorter transcript isoforms in early embryos of both sexes. In addition, one truncated transcript for the gene short-gastrulation encodes a product in embryos that functionally relates to a previously characterized dominant-negative form, which maintains TGF-β signaling in the off-state. In summary, our results reveal a developmental program of short transcripts functioning to help temporally regulate Drosophila embryonic development, keeping cell signaling at early stages to a minimum in order to support its proper initiation at cellularization.
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Affiliation(s)
- Jeremy E Sandler
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jihyun Irizarry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Vincent Stepanik
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Leslie Dunipace
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry Amrhein
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Angelike Stathopoulos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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21
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Rigau M, Juan D, Valencia A, Rico D. Intronic CNVs and gene expression variation in human populations. PLoS Genet 2019; 15:e1007902. [PMID: 30677042 PMCID: PMC6345438 DOI: 10.1371/journal.pgen.1007902] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 12/17/2018] [Indexed: 11/19/2022] Open
Abstract
Introns can be extraordinarily large and they account for the majority of the DNA sequence in human genes. However, little is known about their population patterns of structural variation and their functional implication. By combining the most extensive maps of CNVs in human populations, we have found that intronic losses are the most frequent copy number variants (CNVs) in protein-coding genes in human, with 12,986 intronic deletions, affecting 4,147 genes (including 1,154 essential genes and 1,638 disease-related genes). This intronic length variation results in dozens of genes showing extreme population variability in size, with 40 genes with 10 or more different sizes and up to 150 allelic sizes. Intronic losses are frequent in evolutionarily ancient genes that are highly conserved at the protein sequence level. This result contrasts with losses overlapping exons, which are observed less often than expected by chance and almost exclusively affect primate-specific genes. An integrated analysis of CNVs and RNA-seq data showed that intronic loss can be associated with significant differences in gene expression levels in the population (CNV-eQTLs). These intronic CNV-eQTLs regions are enriched for intronic enhancers and can be associated with expression differences of other genes showing long distance intron-promoter 3D interactions. Our data suggests that intronic structural variation of protein-coding genes makes an important contribution to the variability of gene expression and splicing in human populations.
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Affiliation(s)
- Maria Rigau
- Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - David Juan
- Institut de Biologia Evolutiva, Consejo Superior de Investigaciones Científicas–Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Alfonso Valencia
- Barcelona Supercomputing Center (BSC), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Daniel Rico
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
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22
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Gomulski LM, Mariconti M, Di Cosimo A, Scolari F, Manni M, Savini G, Malacrida AR, Gasperi G. The Nix locus on the male-specific homologue of chromosome 1 in Aedes albopictus is a strong candidate for a male-determining factor. Parasit Vectors 2018; 11:647. [PMID: 30583734 PMCID: PMC6304787 DOI: 10.1186/s13071-018-3215-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background Global concern over the rapid expansion of the Asian tiger mosquito, Aedes albopictus, and its vector competence has highlighted an urgent need to improve currently available population control methods, like the Sterile Insect Technique. Knowledge of the sex determination cascade is a prerequisite for the development of early-stage sexing systems. To this end, we have characterised the putative sex determination gene, Nix, in this species. In Aedes species the chromosome complement consists of three pairs of chromosomes. The sex determination alleles are linked to the smallest homomorphic chromosome. Results We identified the male-specific chromosome 1 of Ae. albopictus that carries the putative male-determining gene Nix. We have also characterised the complete genomic sequence of the Nix gene which is composed of two exons and a short intron. The gene displays different levels of intron retention during development. Comparison of DNA sequences covering most of the Nix gene from individuals across the species range revealed no polymorphism. Conclusions Our characterisation of the Nix gene in Ae. albopictus represents an initial step in the analysis of the sex determination cascade in this species. We found evidence of intron retention (IR) in Nix. IR might play a role in regulating the expression of Nix during development. Our results provide the basis for the development of new genetic control strategies. Electronic supplementary material The online version of this article (10.1186/s13071-018-3215-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ludvik M Gomulski
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Marina Mariconti
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Alessandro Di Cosimo
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Francesca Scolari
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Mosè Manni
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.,Department of Genetic Medicine and Development, University of Geneva Medical School, and Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Grazia Savini
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Anna R Malacrida
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Giuliano Gasperi
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.
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23
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Evolution of maternal and zygotic mRNA complements in the early Drosophila embryo. PLoS Genet 2018; 14:e1007838. [PMID: 30557299 PMCID: PMC6312346 DOI: 10.1371/journal.pgen.1007838] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 12/31/2018] [Accepted: 11/18/2018] [Indexed: 01/19/2023] Open
Abstract
The earliest stages of animal development are controlled by maternally deposited mRNA transcripts and proteins. Once the zygote is able to transcribe its own genome, maternal transcripts are degraded, in a tightly regulated process known as the maternal to zygotic transition (MZT). While this process has been well-studied within model species, we have little knowledge of how the pools of maternal and zygotic transcripts evolve. To characterize the evolutionary dynamics and functional constraints on early embryonic expression, we created a transcriptomic dataset for 14 Drosophila species spanning over 50 million years of evolution, at developmental stages before and after the MZT, and compared our results with a previously published Aedes aegypti developmental time course. We found deep conservation over 250 million years of a core set of genes transcribed only by the zygote. This select group is highly enriched in transcription factors that play critical roles in early development. However, we also identify a surprisingly high level of change in the transcripts represented at both stages over the phylogeny. While mRNA levels of genes with maternally deposited transcripts are more highly conserved than zygotic genes, those maternal transcripts that are completely degraded at the MZT vary dramatically between species. We also show that hundreds of genes have different isoform usage between the maternal and zygotic genomes. Our work suggests that maternal transcript deposition and early zygotic transcription are remarkably dynamic over evolutionary time, despite the widespread conservation of early developmental processes.
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24
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Hamm DC, Harrison MM. Regulatory principles governing the maternal-to-zygotic transition: insights from Drosophila melanogaster. Open Biol 2018; 8:180183. [PMID: 30977698 PMCID: PMC6303782 DOI: 10.1098/rsob.180183] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/09/2018] [Indexed: 12/19/2022] Open
Abstract
The onset of metazoan development requires that two terminally differentiated germ cells, a sperm and an oocyte, become reprogrammed to the totipotent embryo, which can subsequently give rise to all the cell types of the adult organism. In nearly all animals, maternal gene products regulate the initial events of embryogenesis while the zygotic genome remains transcriptionally silent. Developmental control is then passed from mother to zygote through a process known as the maternal-to-zygotic transition (MZT). The MZT comprises an intimately connected set of molecular events that mediate degradation of maternally deposited mRNAs and transcriptional activation of the zygotic genome. This essential developmental transition is conserved among metazoans but is perhaps best understood in the fruit fly, Drosophila melanogaster. In this article, we will review our understanding of the events that drive the MZT in Drosophila embryos and highlight parallel mechanisms driving this transition in other animals.
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Affiliation(s)
| | - Melissa M. Harrison
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA
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25
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Schor IE, Bussotti G, Maleš M, Forneris M, Viales RR, Enright AJ, Furlong EEM. Non-coding RNA Expression, Function, and Variation during Drosophila Embryogenesis. Curr Biol 2018; 28:3547-3561.e9. [PMID: 30393032 PMCID: PMC6264527 DOI: 10.1016/j.cub.2018.09.026] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/10/2018] [Accepted: 09/12/2018] [Indexed: 01/02/2023]
Abstract
Long non-coding RNAs (lncRNAs) can often function in the regulation of gene expression during development; however, their generality as essential regulators in developmental processes and organismal phenotypes remains unclear. Here, we performed a tailored investigation of lncRNA expression and function during Drosophila embryogenesis, interrogating multiple stages, tissue specificity, nuclear localization, and genetic backgrounds. Our results almost double the number of annotated lncRNAs expressed at these embryonic stages. lncRNA levels are generally positively correlated with those of their neighboring genes, with little evidence of transcriptional interference. Using fluorescent in situ hybridization, we report the spatiotemporal expression of 15 new lncRNAs, revealing very dynamic tissue-specific patterns. Despite this, deletion of selected lncRNA genes had no obvious developmental defects or effects on viability under standard and stressed conditions. However, two lncRNA deletions resulted in modest expression changes of a small number of genes, suggesting that they fine-tune expression of non-essential genes. Several lncRNAs have strain-specific expression, indicating that they are not fixed within the population. This intra-species variation across genetic backgrounds may thereby be a useful tool to distinguish rapidly evolving lncRNAs with as yet non-essential roles.
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Affiliation(s)
- Ignacio E Schor
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Departamento de Fisiología, Biología Molecular y Celular, FCEyN, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Giovanni Bussotti
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Hinxton CB10 1SD, UK
| | - Matilda Maleš
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Mattia Forneris
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Rebecca R Viales
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Anton J Enright
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Hinxton CB10 1SD, UK
| | - Eileen E M Furlong
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
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26
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Turner J, Krishna R, Van't Hof AE, Sutton ER, Matzen K, Darby AC. The sequence of a male-specific genome region containing the sex determination switch in Aedes aegypti. Parasit Vectors 2018; 11:549. [PMID: 30342535 PMCID: PMC6195999 DOI: 10.1186/s13071-018-3090-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/31/2018] [Indexed: 11/26/2022] Open
Abstract
Background Aedes aegypti is the principal vector of several important arboviruses. Among the methods of vector control to limit transmission of disease are genetic strategies that involve the release of sterile or genetically modified non-biting males, which has generated interest in manipulating mosquito sex ratios. Sex determination in Ae. aegypti is controlled by a non-recombining Y chromosome-like region called the M locus, yet characterisation of this locus has been thwarted by the repetitive nature of the genome. In 2015, an M locus gene named Nix was identified that displays the qualities of a sex determination switch. Results With the use of a whole-genome bacterial artificial chromosome (BAC) library, we amplified and sequenced a ~200 kb region containing the male-determining gene Nix. In this study, we show that Nix is comprised of two exons separated by a 99 kb intron primarily composed of repetitive DNA, especially transposable elements. Conclusions Nix, an unusually large and highly repetitive gene, exhibits features in common with Y chromosome genes in other organisms. We speculate that the lack of recombination at the M locus has allowed the expansion of repeats in a manner characteristic of a sex-limited chromosome, in accordance with proposed models of sex chromosome evolution in insects. Electronic supplementary material The online version of this article (10.1186/s13071-018-3090-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joe Turner
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.,Oxitec Ltd., 71 Innovation Drive, Milton Park, Abingdon, OX14 4RQ, UK
| | - Ritesh Krishna
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.,IBM Research UK, STFC Daresbury Laboratory, Warrington, WA4 4AD, UK
| | - Arjen E Van't Hof
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.,Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Elizabeth R Sutton
- Oxitec Ltd., 71 Innovation Drive, Milton Park, Abingdon, OX14 4RQ, UK.,Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK.,Sistemic, West of Scotland Science Park, Glasgow, G20 0SP, UK
| | - Kelly Matzen
- Oxitec Ltd., 71 Innovation Drive, Milton Park, Abingdon, OX14 4RQ, UK
| | - Alistair C Darby
- Centre for Genomic Research, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.
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27
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Numerous recursive sites contribute to accuracy of splicing in long introns in flies. PLoS Genet 2018; 14:e1007588. [PMID: 30148878 PMCID: PMC6110457 DOI: 10.1371/journal.pgen.1007588] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/24/2018] [Indexed: 01/10/2023] Open
Abstract
Recursive splicing, a process by which a single intron is removed from pre-mRNA transcripts in multiple distinct segments, has been observed in a small subset of Drosophila melanogaster introns. However, detection of recursive splicing requires observation of splicing intermediates that are inherently unstable, making it difficult to study. Here we developed new computational approaches to identify recursively spliced introns and applied them, in combination with existing methods, to nascent RNA sequencing data from Drosophila S2 cells. These approaches identified hundreds of novel sites of recursive splicing, expanding the catalog of recursively spliced fly introns by 4-fold. A subset of recursive sites were validated by RT-PCR and sequencing. Recursive sites occur in most very long (> 40 kb) fly introns, including many genes involved in morphogenesis and development, and tend to occur near the midpoints of introns. Suggesting a possible function for recursive splicing, we observe that fly introns with recursive sites are spliced more accurately than comparably sized non-recursive introns. The splicing of RNA transcripts is an essential step in the production of mature mRNA molecules, involving removal of intron sequences and joining of flanking exon sequences. Introns are usually removed as a single unit in a two-step catalytic reaction. However, a small subset of introns in flies are removed via splicing of multiple distinct consecutive segments in a process known as recursive splicing. This pathway was thought to be quite rare since intermediates of recursive splicing are seldom detected. In this study, we developed three new computational approaches to identify sequence reads, read pairs and patterns of read accumulation indicative of recursive splicing in Drosophila melanogaster cells using data from sequencing of nascent RNA captured within minutes after transcription. We used these methods to identify hundreds of previously unknown sites of recursive splicing, occurring commonly in fly introns longer than 40kb and often in genes involved in morphogenesis and development. We observed that recursive splicing is associated with increased splicing accuracy of long introns, which are otherwise often spliced inaccurately, potentially explaining its widespread occurrence in long fly introns.
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28
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Pai AA, Henriques T, McCue K, Burkholder A, Adelman K, Burge CB. The kinetics of pre-mRNA splicing in the Drosophila genome and the influence of gene architecture. eLife 2017; 6:32537. [PMID: 29280736 PMCID: PMC5762160 DOI: 10.7554/elife.32537] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/22/2017] [Indexed: 12/28/2022] Open
Abstract
Production of most eukaryotic mRNAs requires splicing of introns from pre-mRNA. The splicing reaction requires definition of splice sites, which are initially recognized in either intron-spanning (‘intron definition’) or exon-spanning (‘exon definition’) pairs. To understand how exon and intron length and splice site recognition mode impact splicing, we measured splicing rates genome-wide in Drosophila, using metabolic labeling/RNA sequencing and new mathematical models to estimate rates. We found that the modal intron length range of 60–70 nt represents a local maximum of splicing rates, but that much longer exon-defined introns are spliced even faster and more accurately. We observed unexpectedly low variation in splicing rates across introns in the same gene, suggesting the presence of gene-level influences, and we identified multiple gene level variables associated with splicing rate. Together our data suggest that developmental and stress response genes may have preferentially evolved exon definition in order to enhance the rate or accuracy of splicing.
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Affiliation(s)
- Athma A Pai
- Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Telmo Henriques
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle, United States.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Kayla McCue
- Program in Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Adam Burkholder
- Center for Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle, United States
| | - Karen Adelman
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle, United States.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Christopher B Burge
- Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Program in Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, United States
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29
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The Function and Evolution of Nuclear Receptors in Insect Embryonic Development. Curr Top Dev Biol 2017; 125:39-70. [DOI: 10.1016/bs.ctdb.2017.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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30
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Gibilisco L, Zhou Q, Mahajan S, Bachtrog D. Alternative Splicing within and between Drosophila Species, Sexes, Tissues, and Developmental Stages. PLoS Genet 2016; 12:e1006464. [PMID: 27935948 PMCID: PMC5147784 DOI: 10.1371/journal.pgen.1006464] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 11/04/2016] [Indexed: 11/19/2022] Open
Abstract
Alternative pre-mRNA splicing ("AS") greatly expands proteome diversity, but little is known about the evolutionary landscape of AS in Drosophila and how it differs between embryonic and adult stages or males and females. Here we study the transcriptomes from several tissues and developmental stages in males and females from four species across the Drosophila genus. We find that 20-37% of multi-exon genes are alternatively spliced. While males generally express a larger number of genes, AS is more prevalent in females, suggesting that the sexes adopt different expression strategies for their specialized function. While the number of total genes expressed increases during early embryonic development, the proportion of expressed genes that are alternatively spliced is highest in the very early embryo, before the onset of zygotic transcription. This indicates that females deposit a diversity of isoforms into the egg, consistent with abundant AS found in ovary. Cluster analysis by gene expression ("GE") levels shows mostly stage-specific clustering in embryonic samples, and tissue-specific clustering in adult tissues. Clustering embryonic stages and adult tissues based on AS profiles results in stronger species-specific clustering, suggesting that diversification of splicing contributes to lineage-specific evolution in Drosophila. Most sex-biased AS found in flies is due to AS in gonads, with little sex-specific splicing in somatic tissues.
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Affiliation(s)
- Lauren Gibilisco
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States of America
| | - Qi Zhou
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States of America
| | - Shivani Mahajan
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States of America
| | - Doris Bachtrog
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States of America
- * E-mail:
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31
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Abstract
Although they do not contribute directly to the proteome, introns frequently contain regulatory elements and can extend the protein coding potential of the genome through alternative splicing. For some genes, the contribution of introns to the time required for transcription can also be functionally significant. We have previously shown that intron length in genes associated with developmental patterning is often highly conserved. In general, sets of genes that require precise coordination in the timing of their expression may be sensitive to changes in transcript length. A prediction of this hypothesis is that evolutionary changes in intron length, when they occur, may be correlated between sets of coordinately expressed genes. To test this hypothesis, we analyzed intron length coevolution in alignments from nine eutherian mammals. Overall, genes that belong to the same protein complex or that are coexpressed were significantly more likely to show evidence of intron length coevolution than matched, randomly sampled genes. Individually, protein complexes involved in the cell cycle showed the strongest evidence of coevolution of intron lengths and clusters of coexpressed genes enriched for cell cycle genes also showed significant evidence of intron length coevolution. Our results reveal a novel aspect of gene coevolution and provide a means to identify genes, protein complexes and biological processes that may be particularly sensitive to changes in transcriptional dynamics.
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Affiliation(s)
- Peter A. Keane
- School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, Ireland
| | - Cathal Seoighe
- School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, Ireland
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32
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Fabre B, Korona D, Groen A, Vowinckel J, Gatto L, Deery MJ, Ralser M, Russell S, Lilley KS. Analysis of Drosophila melanogaster proteome dynamics during embryonic development by a combination of label-free proteomics approaches. Proteomics 2016; 16:2068-80. [PMID: 27029218 PMCID: PMC5737838 DOI: 10.1002/pmic.201500482] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 02/23/2016] [Accepted: 03/24/2016] [Indexed: 12/22/2022]
Abstract
During embryogenesis, organisms undergo considerable cellular remodelling requiring the combined action of thousands of proteins. In case of the well-studied model Drosophila melanogaster, transcriptomic studies, most notably from the modENCODE project, have described in detail changes in gene expression at the mRNA level across development. Although such data are clearly very useful to understand how the genome is regulated during embryogenesis, it is important to understand how changes in gene expression are reflected at the level of the proteome. In this study, we describe a combination of two quantitative label-free approaches, SWATH and data-dependent acquisition, to monitor changes in protein expression across a timecourse of D. melanogaster embryonic development. We demonstrate that both approaches provide robust and reproducible methods for the analysis of proteome changes. In a preliminary analysis of Drosophila embryogenesis, we identified several pathways, including the heat-shock response, nuclear protein import and energy production that are regulated during embryo development. In some cases changes in protein expression mirrored transcript levels across development, whereas other proteins showed signatures of post-transcriptional regulation. Taken together, our pilot study provides a solid platform for a more detailed exploration of the embryonic proteome.
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Affiliation(s)
- Bertrand Fabre
- Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Dagmara Korona
- Department of Genetics, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Arnoud Groen
- Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Jakob Vowinckel
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Laurent Gatto
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
- Computational Proteomics Unit, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Michael J Deery
- Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Markus Ralser
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London, UK
| | - Steven Russell
- Department of Genetics, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Kathryn S Lilley
- Cambridge Centre for Proteomics, Department of Biochemistry, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, University of Cambridge, Cambridge, UK
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
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33
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Mature maternal mRNAs are longer than zygotic ones and have complex degradation kinetics in sea urchin. Dev Biol 2016; 414:121-31. [PMID: 27085752 DOI: 10.1016/j.ydbio.2016.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/16/2016] [Accepted: 04/10/2016] [Indexed: 11/22/2022]
Abstract
Early in embryogenesis, maternally deposited transcripts are degraded and new zygotic transcripts are generated during the maternal to zygotic transition. Recent works have shown that early zygotic transcripts are short compared to maternal transcripts, in zebrafish and Drosophila species. The reduced zygotic transcript length was attributed to the short cell cycle in these organisms that prevents the transcription of long primary transcripts (intron delay). Here we study the length of maternal mRNAs and their degradation kinetics in two sea urchin species to further the understanding of maternal gene usage and processing. Early zygotic primary transcripts and mRNAs are shorter than maternal ones in the sea urchin, Strongylocentrotus purpuratus. Yet, while primary transcripts length increases when cell cycle lengthens, typical for intron delay, the relatively short length of zygotic mRNAs is consistent. The enhanced mRNA length is due to significantly longer maternal open reading frames and 3'UTRs compared to the zygotic lengths, a ratio that does not change with developmental time. This implies unique usage of both coding sequences and regulatory information in the maternal stage compared to the zygotic stages. We extracted the half-lifetimes due to maternal and zygotic degradation mechanisms from high-density time course of a set of maternal mRNAs in Paracentrotus lividus. The degradation rates due to maternal and zygotic degradation mechanisms are not correlated, indicating that these mechanisms are independent and relay on different regulatory information. Our studies illuminate specific structural and kinetic properties of sea urchin maternal mRNAs that might be broadly shared by other organisms.
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34
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Bryant SV, Gardiner DM. The relationship between growth and pattern formation. REGENERATION (OXFORD, ENGLAND) 2016; 3:103-22. [PMID: 27499882 PMCID: PMC4895327 DOI: 10.1002/reg2.55] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 04/02/2016] [Accepted: 04/04/2016] [Indexed: 12/11/2022]
Abstract
Successful development depends on the creation of spatial gradients of transcription factors within developing fields, and images of graded distributions of gene products populate the pages of developmental biology journals. Therefore the challenge is to understand how the graded levels of intracellular transcription factors are generated across fields of cells. We propose that transcription factor gradients are generated as a result of an underlying gradient of cell cycle lengths. Very long cell cycles will permit accumulation of a high level of a gene product encoded by a large transcription unit, whereas shorter cell cycles will permit progressively fewer transcripts to be completed due to gating of transcription by the cell cycle. We also propose that the gradients of cell cycle lengths are generated by gradients of extracellular morphogens/growth factors. The model of cell cycle gated transcriptional regulation brings focus back to the functional role of morphogens as cell cycle regulators, and proposes a specific and testable mechanism by which morphogens, in their roles as growth factors (how they were originally discovered), also determine cell fate.
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35
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Sharma R, Beer K, Iwanov K, Schmöhl F, Beckmann PI, Schröder R. The single fgf receptor gene in the beetle Tribolium castaneum codes for two isoforms that integrate FGF8- and Branchless-dependent signals. Dev Biol 2015; 402:264-75. [PMID: 25864412 DOI: 10.1016/j.ydbio.2015.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 11/16/2022]
Abstract
The precise regulation of cell-cell communication by numerous signal-transduction pathways is fundamental for many different processes during embryonic development. One important signalling pathway is the evolutionary conserved fibroblast-growth-factor (FGF)-pathway that controls processes like cell migration, axis specification and mesoderm formation in vertebrate and invertebrate animals. In the model insect Drosophila, the FGF ligand / receptor combinations of FGF8 (Pyramus and Thisbe) / Heartless (Htl) and Branchless (Bnl) / Breathless (Btl) are required for the migration of mesodermal cells and for the formation of the tracheal network respectively with both the receptors functioning independently of each other. However, only a single fgf-receptor gene (Tc-fgfr) has been identified in the genome of the beetle Tribolium. We therefore asked whether both the ligands Fgf8 and Bnl could transduce their signal through a common FGF-receptor in Tribolium. Indeed, we found that the function of the single Tc-fgfr gene is essential for mesoderm differentiation as well as for the formation of the tracheal network during early development. Ligand specific RNAi for Tc-fgf8 and Tc-bnl resulted in two distinct non-overlapping phenotypes of impaired mesoderm differentiation and abnormal formation of the tracheal network in Tc-fgf8- and Tc-bnl(RNAi) embryos respectively. We further show that the single Tc-fgfr gene encodes at least two different receptor isoforms that are generated through alternative splicing. We in addition demonstrate through exon-specific RNAi their distinct tissue-specific functions. Finally, we discuss the structure of the fgf-receptor gene from an evolutionary perspective.
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Affiliation(s)
- Rahul Sharma
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany
| | - Katharina Beer
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany
| | - Katharina Iwanov
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany
| | - Felix Schmöhl
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany
| | - Paula Indigo Beckmann
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany
| | - Reinhard Schröder
- University of Rostock, Biological Sciences, Department of Genetics, Albert-Einsteinstr. 3, 18059 Rostock, Germany.
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36
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Heyn P, Kalinka AT, Tomancak P, Neugebauer KM. Introns and gene expression: cellular constraints, transcriptional regulation, and evolutionary consequences. Bioessays 2014; 37:148-54. [PMID: 25400101 PMCID: PMC4654234 DOI: 10.1002/bies.201400138] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A gene's “expression profile” denotes the number of transcripts present relative to all other transcripts. The overall rate of transcript production is determined by transcription and RNA processing rates. While the speed of elongating RNA polymerase II has been characterized for many different genes and organisms, gene-architectural features – primarily the number and length of exons and introns – have recently emerged as important regulatory players. Several new studies indicate that rapidly cycling cells constrain gene-architecture toward short genes with a few introns, allowing efficient expression during short cell cycles. In contrast, longer genes with long introns exhibit delayed expression, which can serve as timing mechanisms for patterning processes. These findings indicate that cell cycle constraints drive the evolution of gene-architecture and shape the transcriptome of a given cell type. Furthermore, a tendency for short genes to be evolutionarily young hints at links between cellular constraints and the evolution of animal ontogeny.
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Affiliation(s)
- Patricia Heyn
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, UK
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