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Liu Y, Niu J, Ye F, Solberg T, Lu B, Wang C, Nowacki M, Gao S. Dynamic DNA N 6-adenine methylation (6mA) governs the encystment process, showcased in the unicellular eukaryote Pseudocohnilembus persalinus. Genome Res 2024; 34:256-271. [PMID: 38471739 PMCID: PMC10984389 DOI: 10.1101/gr.278796.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/14/2024] [Indexed: 03/14/2024]
Abstract
The formation of resting cysts commonly found in unicellular eukaryotes is a complex and highly regulated survival strategy against environmental stress that involves drastic physiological and biochemical changes. Although most studies have focused on the morphology and structure of cysts, little is known about the molecular mechanisms that control this process. Recent studies indicate that DNA N 6-adenine methylation (6mA) could be dynamically changing in response to external stimuli; however, its potential role in the regulation of cyst formation remains unknown. We used the ciliate Pseudocohnilembus persalinus, which can be easily induced to form cysts to investigate the dynamic pattern of 6mA in trophonts and cysts. Single-molecule real-time (SMRT) sequencing reveals high levels of 6mA in trophonts that decrease in cysts, along with a conversion of symmetric 6mA to asymmetric 6mA. Further analysis shows that 6mA, a mark of active transcription, is involved in altering the expression of encystment-related genes through changes in 6mA levels and 6mA symmetric-to-asymmetric conversion. Most importantly, we show that reducing 6mA levels by knocking down the DNA 6mA methyltransferase PpAMT1 accelerates cyst formation. Taken together, we characterize the genome-wide 6mA landscape in P. persalinus and provide insights into the role of 6mA in gene regulation under environmental stress in eukaryotes. We propose that 6mA acts as a mark of active transcription to regulate the encystment process along with symmetric-to-asymmetric conversion, providing important information for understanding the molecular response to environmental cues from the perspective of 6mA modification.
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Affiliation(s)
- Yongqiang Liu
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao 266237, China
| | - Junhua Niu
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao 266237, China
| | - Fei Ye
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao 266237, China
| | - Therese Solberg
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
- Department of Molecular Biology, Keio University School of Medicine, 160-8582 Tokyo, Japan
- Human Biology Microbiome Quantum Research Center (WPI-Bio2Q), Keio University, 108-8345 Tokyo, Japan
| | - Borong Lu
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao 266237, China
| | - Chundi Wang
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
- Laboratory of Marine Protozoan Biodiversity and Evolution, Marine College, Shandong University, Weihai 264209, China
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland
| | - Shan Gao
- MOE Key Laboratory of Evolution and Marine Biodiversity and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China;
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao 266237, China
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Jin D, Li C, Chen X, Wang Y, Al-Rasheid KAS, Stover NA, Shao C, Zhang T. Decryption of the survival "black box": gene family expansion promotes the encystment in ciliated protists. BMC Genomics 2024; 25:286. [PMID: 38500030 PMCID: PMC10946202 DOI: 10.1186/s12864-024-10207-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/11/2024] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND Encystment is an important survival strategy extensively employed by microbial organisms to survive unfavorable conditions. Single-celled ciliated protists (ciliates) are popular model eukaryotes for studying encystment, whereby these cells degenerate their ciliary structures and develop cyst walls, then reverse the process under more favorable conditions. However, to date, the evolutionary basis and mechanism for encystment in ciliates is largely unknown. With the rapid development of high-throughput sequencing technologies, genome sequencing and comparative genomics of ciliates have become effective methods to provide insights into above questions. RESULTS Here, we profiled the MAC genome of Pseudourostyla cristata, a model hypotrich ciliate for encystment studies. Like other hypotrich MAC genomes, the P. cristata MAC genome is extremely fragmented with a single gene on most chromosomes, and encodes introns that are generally small and lack a conserved branch point for pre-mRNA splicing. Gene family expansion analyses indicate that multiple gene families involved in the encystment are expanded during the evolution of P. cristata. Furthermore, genomic comparisons with other five representative hypotrichs indicate that gene families of phosphorelay sensor kinase, which play a role in the two-component signal transduction system that is related to encystment, show significant expansion among all six hypotrichs. Additionally, cyst wall-related chitin synthase genes have experienced structural changes that increase them from single-exon to multi-exon genes during evolution. These genomic features potentially promote the encystment in hypotrichs and enhance their ability to survive in adverse environments during evolution. CONCLUSIONS We systematically investigated the genomic structure of hypotrichs and key evolutionary phenomenon, gene family expansion, for encystment promotion in ciliates. In summary, our results provided insights into the evolutionary mechanism of encystment in ciliates.
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Affiliation(s)
- Didi Jin
- Laboratory of Biodiversity and Evolution of Protozoa in Wetland, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Chao Li
- Key Laboratory of Evolution & Marine Biodiversity (Ministry of Education), and Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, 266003, China
| | - Xiao Chen
- Laboratory of Marine Protozoan Biodiversity and Evolution, Marine College, Shandong University, Weihai, 264209, China
- Suzhou Research Institute, Shandong University, Suzhou, 215123, China
| | - Yurui Wang
- Laboratory of Biodiversity and Evolution of Protozoa in Wetland, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China
| | - Khaled A S Al-Rasheid
- Zoology Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Naomi A Stover
- Department of Biology, Bradley University, Peoria, 61625, USA
| | - Chen Shao
- Laboratory of Biodiversity and Evolution of Protozoa in Wetland, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China.
| | - Tengteng Zhang
- Laboratory of Biodiversity and Evolution of Protozoa in Wetland, College of Life Sciences, Shaanxi Normal University, Xi'an, 710119, China.
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Bechara ST, Kabbani LES, Maurer-Alcalá XX, Nowacki M. Identification of novel, functional, long noncoding RNAs involved in programmed, large-scale genome rearrangements. RNA (NEW YORK, N.Y.) 2022; 28:1110-1127. [PMID: 35680167 PMCID: PMC9297840 DOI: 10.1261/rna.079134.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Noncoding RNAs (ncRNAs) make up to ∼98% percent of the transcriptome of a given organism. In recent years, one relatively new class of ncRNAs, long noncoding RNAs (lncRNAs), were shown to be more than mere by-products of gene expression and regulation. The unicellular eukaryote Paramecium tetraurelia is a member of the ciliate phylum, an extremely heterogeneous group of organisms found in most bodies of water across the globe. A hallmark of ciliate genetics is nuclear dimorphism and programmed elimination of transposons and transposon-derived DNA elements, the latter of which is essential for the maintenance of the somatic genome. Paramecium and ciliates in general harbor a plethora of different ncRNA species, some of which drive the process of large-scale genome rearrangements, including DNA elimination, during sexual development. Here, we identify and validate the first known functional lncRNAs in ciliates to date. Using deep-sequencing and subsequent bioinformatic processing and experimental validation, we show that Paramecium expresses at least 15 lncRNAs. These candidates were predicted by a highly conservative pipeline, and informatic analyses hint at differential expression during development. Depletion of two lncRNAs, lnc1 and lnc15, resulted in clear phenotypes, decreased survival, morphological impairment, and a global effect on DNA elimination.
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Affiliation(s)
- Sebastian T Bechara
- Institute of Cell Biology, University of Bern, Bern 3012, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern 3012, Switzerland
| | - Lyna E S Kabbani
- Institute of Cell Biology, University of Bern, Bern 3012, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern 3012, Switzerland
| | - Xyrus X Maurer-Alcalá
- Institute of Cell Biology, University of Bern, Bern 3012, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern 3012, Switzerland
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Bern 3012, Switzerland
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Zhang L, Song J, Peng L, Xie W, Li S, Wang J. Comprehensive Biochemical, Physiological, and Transcriptomic Analyses Provide Insights Into Floral Bud Dormancy in Rhododendron delavayi Franch. Front Genet 2022; 13:856922. [PMID: 35656313 PMCID: PMC9152171 DOI: 10.3389/fgene.2022.856922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/19/2022] [Indexed: 01/17/2023] Open
Abstract
Due to a scarcity of relevant data, the ornamental woody flower Rhododendron delavayi Franch. is examined in the current study for its low temperature-induced floral bud dormancy (late October-end December) aspect. This study used transcriptome data profiling and co-expression network analyses to identify the interplay between endogenous hormones and bud dormancy phases such as pre-dormancy, para-dormancy, endo-dormancy, eco-dormancy, and dormancy release. The biochemical and physiological assays revealed the significance of the abundance of phytohormones (abscisic acid, auxin, zeatin, and gibberellins), carbohydrate metabolism, oxidative species, and proteins (soluble proteins, proline, and malondialdehyde) in the regulatory mechanism of floral bud dormancy. The transcriptome sequencing generated 65,531 transcripts, out of which 504, 514, 307, and 240 expressed transcripts were mapped uniquely to pre-, para-, endo-, and eco-phases of dormancy, showing their roles in the stimulation of dormancy. The transcripts related to LEA29, PGM, SAUR family, RPL9e, ATRX, FLOWERING LOCUS T, SERK1, ABFs, ASR2, and GID1 were identified as potential structural genes involved in floral bud dormancy. The transcription factors, including Zinc fingers, CAD, MADS-box family, MYB, and MYC2, revealed their potential regulatory roles concerning floral bud dormancy. The gene co-expression analysis highlighted essential hub genes involved in cold stress adaptations encoding proteins, viz, SERPIN, HMA, PMEI, LEA_2, TRX, PSBT, and AMAT. We exposed the connection among low temperature-induced dormancy in floral buds, differentially expressed genes, and hub genes via strict screening steps to escalate the confidence in selected genes as being truly putative in the pathways regulating bud dormancy mechanism. The identified candidate genes may prove worthy of further in-depth studies on molecular mechanisms involved in floral bud dormancy of Rhododendron species.
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Affiliation(s)
- Lu Zhang
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
| | - Jie Song
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
| | - Lvchun Peng
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
| | - Weijia Xie
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
| | - Shifeng Li
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
| | - Jihua Wang
- Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, China.,National Engineering Research Center for Ornamental Horticulture, Kunming, China
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