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Rizos I, Frada MJ, Bittner L, Not F. Life cycle strategies in free-living unicellular eukaryotes: Diversity, evolution, and current molecular tools to unravel the private life of microorganisms. J Eukaryot Microbiol 2024:e13052. [PMID: 39085163 DOI: 10.1111/jeu.13052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 06/12/2024] [Accepted: 07/08/2024] [Indexed: 08/02/2024]
Abstract
An astonishing range of morphologies and life strategies has arisen across the vast diversity of protists, allowing them to thrive in most environments. In model protists, like Tetrahymena, Dictyostelium, or Trypanosoma, life cycles involving multiple life stages with different morphologies have been well characterized. In contrast, knowledge of the life cycles of free-living protists, which primarily consist of uncultivated environmental lineages, remains largely fragmentary. Various life stages and lineage-specific cellular innovations have been observed in the field for uncultivated protists, but such innovations generally lack functional characterization and have unknown physiological and ecological roles. In the actual state of knowledge, evidence of sexual processes is confirmed for 20% of free-living protist lineages. Nevertheless, at the onset of eukaryotic diversification, common molecular trends emerged to promote genetic recombination, establishing sex as an inherent feature of protists. Here, we review protist life cycles from the viewpoint of life cycle transitions and genetics across major eukaryotic lineages. We focus on the scarcely observed sexual cycle of free-living protists, summarizing evidence for its existence and describing key genes governing its progression, as well as, current methods for studying the genetics of sexual cycles in both cultivable and uncultivated protist groups.
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Affiliation(s)
- Iris Rizos
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université Des Antilles, Paris, France
- CNRS, AD2M-UMR7144 Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Miguel J Frada
- Department of Ecology, Evolution and Behavior, Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel
| | - Lucie Bittner
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université Des Antilles, Paris, France
- Institut Universitaire de France, Paris, France
| | - Fabrice Not
- CNRS, AD2M-UMR7144 Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
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2
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Li Y, He J, Zhang X, Deng X. The draft genome of Nitzschia closterium f. minutissima and transcriptome analysis reveals novel insights into diatom biosilicification. BMC Genomics 2024; 25:560. [PMID: 38840265 PMCID: PMC11151724 DOI: 10.1186/s12864-024-10479-9] [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: 01/16/2024] [Accepted: 05/30/2024] [Indexed: 06/07/2024] Open
Abstract
BACKGROUND Nitzschia closterium f. minutissima is a commonly available diatom that plays important roles in marine aquaculture. It was originally classified as Nitzschia (Bacillariaceae, Bacillariophyta) but is currently regarded as a heterotypic synonym of Phaeodactylum tricornutum. The aim of this study was to obtain the draft genome of the marine microalga N. closterium f. minutissima to understand its phylogenetic placement and evolutionary specialization. Given that the ornate hierarchical silicified cell walls (frustules) of diatoms have immense applications in nanotechnology for biomedical fields, biosensors and optoelectric devices, transcriptomic data were generated by using reference genome-based read mapping to identify significantly differentially expressed genes and elucidate the molecular processes involved in diatom biosilicification. RESULTS In this study, we generated 13.81 Gb of pass reads from the PromethION sequencer. The draft genome of N. closterium f. minutissima has a total length of 29.28 Mb, and contains 28 contigs with an N50 value of 1.23 Mb. The GC content was 48.55%, and approximately 18.36% of the genome assembly contained repeat sequences. Gene annotation revealed 9,132 protein-coding genes. The results of comparative genomic analysis showed that N. closterium f. minutissima was clustered as a sister lineage of Phaeodactylum tricornutum and the divergence time between them was estimated to be approximately 17.2 million years ago (Mya). CAFF analysis demonstrated that 220 gene families that significantly changed were unique to N. closterium f. minutissima and that 154 were specific to P. tricornutum, moreover, only 26 gene families overlapped between these two species. A total of 818 DEGs in response to silicon were identified in N. closterium f. minutissima through RNA sequencing, these genes are involved in various molecular processes such as transcription regulator activity. Several genes encoding proteins, including silicon transporters, heat shock factors, methyltransferases, ankyrin repeat domains, cGMP-mediated signaling pathways-related proteins, cytoskeleton-associated proteins, polyamines, glycoproteins and saturated fatty acids may contribute to the formation of frustules in N. closterium f. minutissima. CONCLUSIONS Here, we described a draft genome of N. closterium f. minutissima and compared it with those of eight other diatoms, which provided new insight into its evolutionary features. Transcriptome analysis to identify DEGs in response to silicon will help to elucidate the underlying molecular mechanism of diatom biosilicification in N. closterium f. minutissima.
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Affiliation(s)
- Yajun Li
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (CATAS) & Key Laboratory of Biology and Genetic Resources of Tropical Crops of Hainan Province, Haikou, 571101, China.
- Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bioresources, Haikou, 571101, China.
| | - Jinman He
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (CATAS) & Key Laboratory of Biology and Genetic Resources of Tropical Crops of Hainan Province, Haikou, 571101, China
- Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bioresources, Haikou, 571101, China
| | - Xiuxia Zhang
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (CATAS) & Key Laboratory of Biology and Genetic Resources of Tropical Crops of Hainan Province, Haikou, 571101, China
- Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bioresources, Haikou, 571101, China
| | - Xiaodong Deng
- Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (CATAS) & Key Laboratory of Biology and Genetic Resources of Tropical Crops of Hainan Province, Haikou, 571101, China.
- Hainan Provincial Key Laboratory for Functional Components Research and Utilization of Marine Bioresources, Haikou, 571101, China.
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3
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Audoor S, Bilcke G, Pargana K, Belišová D, Thierens S, Van Bel M, Sterck L, Rijsdijk N, Annunziata R, Ferrante MI, Vandepoele K, Vyverman W. Transcriptional chronology reveals conserved genes involved in pennate diatom sexual reproduction. Mol Ecol 2024; 33:e17320. [PMID: 38506152 DOI: 10.1111/mec.17320] [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: 08/30/2023] [Revised: 01/23/2024] [Accepted: 03/07/2024] [Indexed: 03/21/2024]
Abstract
Sexual reproduction is a major driver of adaptation and speciation in eukaryotes. In diatoms, siliceous microalgae with a unique cell size reduction-restitution life cycle and among the world's most prolific primary producers, sex also acts as the main mechanism for cell size restoration through the formation of an expanding auxospore. However, the molecular regulators of the different stages of sexual reproduction and size restoration are poorly explored. Here, we combined RNA sequencing with the assembly of a 55 Mbp reference genome for Cylindrotheca closterium to identify patterns of gene expression during different stages of sexual reproduction. These were compared with a corresponding transcriptomic time series of Seminavis robusta to assess the degree of expression conservation. Integrative orthology analysis revealed 138 one-to-one orthologues that are upregulated during sex in both species, among which 56 genes consistently upregulated during cell pairing and gametogenesis, and 11 genes induced when auxospores are present. Several early, sex-specific transcription factors and B-type cyclins were also upregulated during sex in other pennate and centric diatoms, pointing towards a conserved core regulatory machinery for meiosis and gametogenesis across diatoms. Furthermore, we find molecular evidence that the pheromone-induced cell cycle arrest is short-lived in benthic diatoms, which may be linked to their active mode of mate finding through gliding. Finally, we exploit the temporal resolution of our comparative analysis to report the first marker genes for auxospore identity called AAE1-3 ("Auxospore-Associated Expression"). Altogether, we introduce a multi-species model of the transcriptional dynamics during size restoration in diatoms and highlight conserved gene expression dynamics during different stages of sexual reproduction.
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Affiliation(s)
- Sien Audoor
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
| | - Gust Bilcke
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Katerina Pargana
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
| | - Darja Belišová
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Sander Thierens
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Michiel Van Bel
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Lieven Sterck
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Nadine Rijsdijk
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | | | - Maria Immacolata Ferrante
- Stazione Zoologica Anton Dohrn, Naples, Italy
- Associate to the National Institute of Oceanography and Applied Geophysics, Trieste, Italy
| | - Klaas Vandepoele
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for AI & Computational Biology, VIB, Ghent, Belgium
| | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Department of Biology, University Ghent, Ghent, Belgium
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Ji N, Wang J, Huang W, Huang J, Cai Y, Sun S, Shen X, Liang Y. Transcriptome analysis of the harmful alga Heterosigma akashiwo under a 24-hour light-dark cycle. HARMFUL ALGAE 2024; 133:102601. [PMID: 38485440 DOI: 10.1016/j.hal.2024.102601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 01/29/2024] [Accepted: 02/05/2024] [Indexed: 03/19/2024]
Abstract
The photoperiod, which is defined as the period of time within a 24-hour time frame that light is available, is an important environmental regulator of several physiological processes in phytoplankton, including harmful bloom-forming phytoplankton. The ichthyotoxic raphidophyte Heterosigma akashiwo is a globally distributed bloom-forming phytoplankton. Despite extensive studies on the ecological impact of H. akashiwo, the influence of the photoperiod on crucial biological processes of this species remains unclear. In this study, gene expression in H. akashiwo was analyzed over a 24-hour light-dark (14:10) treatment period. Approximately 36 % of unigenes in H. akashiwo were differentially expressed during this 24-hour treatment period, which is indicative of their involvement in the response to light-dark variation. Notably, the number of differentially expressed genes exhibited an initial increase followed by a subsequent decrease as the sampling time progressed (T0 vs. other time points). Unigenes associated with photosynthesis and photoprotection reached their peak expression levels after 2-4 h of illumination (T12-T14). In contrast, the expression of unigenes associated with DNA replication peaked at the starting point of the dark period (T0). Furthermore, although several unigenes annotated to photoreceptors displayed potential diel periodicity, genes from various photoreceptor families (such as phytochrome and cryptochrome) showed unique expression patterns. Collectively, our findings offer novel perspectives on the response of H. akashiwo to the light-dark cycle, serving as a valuable resource for investigating the physiology and ecology of this species.
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Affiliation(s)
- Nanjing Ji
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China; Jiangsu Marine Resources Development Research Institute, Lianyungang 222005, China; CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
| | - Junyue Wang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Wencong Huang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Jinwang Huang
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yuefeng Cai
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Song Sun
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Xin Shen
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yue Liang
- Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
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5
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Ferrante MI, Broccoli A, Montresor M. The pennate diatom Pseudo-nitzschia multistriata as a model for diatom life cycles, from the laboratory to the sea. JOURNAL OF PHYCOLOGY 2023; 59:637-643. [PMID: 37256710 DOI: 10.1111/jpy.13342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 06/02/2023]
Abstract
Phytoplankton dynamics are regulated by external cues, such as light and nutrients, as well as by biotic interactions and endogenous controls linked to life cycle characteristics. The planktonic pennate diatom Pseudo-nitzschia multistriata, with a heterothallic mating system with two opposite mating types (MTs), represents a model for the study of diatom life cycles. P. multistriata is a toxic species, able to produce the neurotoxin domoic acid. First described in Japan in 1993, it was detected at the long-term monitoring station MareChiara (Gulf of Naples, Italy) in 1995. Since then, P. multistriata has been reported from several worldwide coastal sites. A large body of knowledge has been produced on its ecology, genetic diversity, and life cycle characteristics. The availability of these data, the ecological relevance of the Pseudo-nitzschia genus, and its controllable life cycle with a short generation time made it an ideal species to develop a genetic model system for diatoms. To enable functional studies, a 59 Mb genome sequence and several transcriptomic data were produced, and genetic transformation was optimized. These tools allowed the discovery of the first mating-type determining gene for diatoms. Gene expression studies and metabolomics analyses defined genes and molecules underpinning different phases of the process of sexual reproduction. This model system, developed to explore the genetics of diatom life cycles, offers the opportunity to parallel experimental observations in the laboratory using in situ meta-omics analyses along space and time, empowering knowledge on the biology and ecology of the genus.
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Affiliation(s)
- Maria Immacolata Ferrante
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Naples, Italy
- National Institute of Oceanography and Applied Geophysics, Trieste, Italy
| | - Andrea Broccoli
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Marina Montresor
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Naples, Italy
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6
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Pinseel E, Nakov T, Van den Berge K, Downey KM, Judy KJ, Kourtchenko O, Kremp A, Ruck EC, Sjöqvist C, Töpel M, Godhe A, Alverson AJ. Strain-specific transcriptional responses overshadow salinity effects in a marine diatom sampled along the Baltic Sea salinity cline. THE ISME JOURNAL 2022; 16:1776-1787. [PMID: 35383290 PMCID: PMC9213524 DOI: 10.1038/s41396-022-01230-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 03/16/2022] [Accepted: 03/21/2022] [Indexed: 05/01/2023]
Abstract
The salinity gradient separating marine and freshwater environments represents a major ecological divide for microbiota, yet the mechanisms by which marine microbes have adapted to and ultimately diversified in freshwater environments are poorly understood. Here, we take advantage of a natural evolutionary experiment: the colonization of the brackish Baltic Sea by the ancestrally marine diatom Skeletonema marinoi. To understand how diatoms respond to low salinity, we characterized transcriptomic responses of acclimated S. marinoi grown in a common garden. Our experiment included eight strains from source populations spanning the Baltic Sea salinity cline. Gene expression analysis revealed that low salinities induced changes in the cellular metabolism of S. marinoi, including upregulation of photosynthesis and storage compound biosynthesis, increased nutrient demand, and a complex response to oxidative stress. However, the strain effect overshadowed the salinity effect, as strains differed significantly in their response, both regarding the strength and the strategy (direction of gene expression) of their response. The high degree of intraspecific variation in gene expression observed here highlights an important but often overlooked source of biological variation associated with how diatoms respond to environmental change.
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Affiliation(s)
- Eveline Pinseel
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA.
| | - Teofil Nakov
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Koen Van den Berge
- Department of Statistics, University of California, Berkeley, CA, USA
- Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Ghent, Belgium
- Bioinformatics Institute Ghent, Ghent University, Ghent, Belgium
| | - Kala M Downey
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Kathryn J Judy
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Olga Kourtchenko
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Anke Kremp
- Leibniz-Institute for Baltic Sea Research Warnemünde, Rostock, Germany
| | - Elizabeth C Ruck
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Conny Sjöqvist
- Environmental and Marine Biology, Åbo Akademi University, Åbo, Finland
| | - Mats Töpel
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Anna Godhe
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Andrew J Alverson
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA.
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7
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Annunziata R, Mele BH, Marotta P, Volpe M, Entrambasaguas L, Mager S, Stec K, d’Alcalà MR, Sanges R, Finazzi G, Iudicone D, Montresor M, Ferrante MI. Trade-off between sex and growth in diatoms: Molecular mechanisms and demographic implications. SCIENCE ADVANCES 2022; 8:eabj9466. [PMID: 35044817 PMCID: PMC8769554 DOI: 10.1126/sciadv.abj9466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Diatoms are fast-growing and winning competitors in aquatic environments, possibly due to optimized growth performance. However, their life cycles are complex, heteromorphic, and not fully understood. Here, we report on the fine control of cell growth and physiology during the sexual phase of the marine diatom Pseudo-nitzschia multistriata. We found that mating, under nutrient replete conditions, induces a prolonged growth arrest in parental cells. Transcriptomic analyses revealed down-regulation of genes related to major metabolic functions from the early phases of mating. Single-cell photophysiology also pinpointed an inhibition of photosynthesis and storage lipids accumulated in the arrested population, especially in gametes and zygotes. Numerical simulations revealed that growth arrest affects the balance between parental cells and their siblings, possibly favoring the new generation. Thus, in addition to resources availability, life cycle traits contribute to shaping the species ecological niches and must be considered to describe and understand the structure of plankton communities.
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Affiliation(s)
- Rossella Annunziata
- Stazione Zoologica Anton Dohrn, Napoli, Italy
- Corresponding author. (R.A.); (M.I.F.)
| | | | | | | | | | | | | | | | - Remo Sanges
- International School for Advanced Studies (SISSA), Via Bonomea 265, Trieste 34136, Italy
| | - Giovanni Finazzi
- Université Grenoble Alpes (UGA), Centre National Recherche Scientifique (CNRS), Commissariat Energie Atomique, Energies Alternatives (CEA), Institut National Recherche Agriculture, Alimentation, Environnement (INRAE), Interdisciplinary Research Institute of Grenoble, IRIG-Laboratoire de Physiologie Cellulaire et Végétale, Grenoble, France
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8
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Liu S, Wang Y, Xu Q, Zhang M, Chen N. Comparative analysis of full-length mitochondrial genomes of five Skeletonema species reveals conserved genome organization and recent speciation. BMC Genomics 2021; 22:746. [PMID: 34654361 PMCID: PMC8520197 DOI: 10.1186/s12864-021-07999-z] [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: 03/06/2021] [Accepted: 09/03/2021] [Indexed: 12/05/2022] Open
Abstract
Background Skeletonema species are prominent primary producers, some of which can also cause massive harmful algal blooms (HABs) in coastal waters under specific environmental conditions. Nevertheless, genomic information of Skeletonema species is currently limited, hindering advanced research on their role as primary producers and as HAB species. Mitochondrial genome (mtDNA) has been extensively used as “super barcode” in the phylogenetic analyses and comparative genomic analyses. However, of the 21 accepted Skeletonema species, full-length mtDNAs are currently available only for a single species, S. marinoi. Results In this study, we constructed full-length mtDNAs for six strains of five Skeletonema species, including S. marinoi, S. tropicum, S. grevillei, S. pseudocostatum and S. costatum (with two strains), which were isolated from coastal waters in China. The mtDNAs of all of these Skeletonema species were compact with short intergenic regions, no introns, and no repeat regions. Comparative analyses of these Skeletonema mtDNAs revealed high conservation, with a few discrete regions of high variations, some of which could be used as molecular markers for distinguishing Skeletonema species and for tracking the biogeographic distribution of these species with high resolution and specificity. We estimated divergence times among these Skeletonema species using 34 mtDNAs genes with fossil data as calibration point in PAML, which revealed that the Skeletonema species formed the independent clade diverging from Thalassiosira species approximately 48.30 Mya. Conclusions The availability of mtDNAs of five Skeletonema species provided valuable reference sequences for further evolutionary studies including speciation time estimation and comparative genomic analysis among diatom species. Divergent regions could be used as molecular markers for tracking different Skeletonema species in the fields of coastal regions. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07999-z.
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Affiliation(s)
- Shuya Liu
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 266071, Qingdao, China.,Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yichao Wang
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 266071, Qingdao, China.,Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.,University of Chinese Academy of Sciences, Beijing, 10039, China
| | - Qing Xu
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 266071, Qingdao, China.,Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Mengjia Zhang
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 266071, Qingdao, China.,Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.,University of Chinese Academy of Sciences, Beijing, 10039, China
| | - Nansheng Chen
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, 266071, Qingdao, China. .,Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China. .,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China. .,Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.
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9
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Light intensity and spectral composition drive reproductive success in the marine benthic diatom Seminavis robusta. Sci Rep 2021; 11:17560. [PMID: 34475415 PMCID: PMC8413402 DOI: 10.1038/s41598-021-92838-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/09/2021] [Indexed: 12/13/2022] Open
Abstract
The properties of incident light play a crucial role in the mating process of diatoms, a group of ecologically important microalgae. While species-specific requirements for light intensity and photoperiod have been observed in several diatom species, little is known about the light spectrum that allows sexual reproduction. Here, we study the effects of spectral properties and light intensity on the initiation and progression of sexual reproduction in the model benthic diatom Seminavis robusta. We found that distinct stages of the mating process have different requirements for light. Vigorous mating pair formation occurred under a broad range of light intensities, ranging from 10 to 81 µE m−2 s−1, while gametogenesis and subsequent stages were strongly affected by moderate light intensities of 27 µE m−2 s−1 and up. In addition, light of blue or blue–green wavelengths was required for the formation of mating pairs. Combining flow cytometric analysis with expression profiling of the diatom-specific cyclin dsCyc2 suggests that progression through a blue light-dependent checkpoint in the G1 cell cycle phase is essential for induction of sexual reproduction. Taken together, we expand the current model of mating in benthic pennate diatoms, which relies on the interplay between light, cell cycle and sex pheromone signaling.
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Petrova DP, Khabudaev KV, Bedoshvili YD, Likhoshway YV. Phylogeny and structural peculiarities of the EB proteins of diatoms. J Struct Biol 2021; 213:107775. [PMID: 34364984 DOI: 10.1016/j.jsb.2021.107775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 11/25/2022]
Abstract
The end-binding proteins are a family of microtubule-associated proteins; this family belongs to plus-end-tracking proteins (+TIPs) that regulate microtubule growth and stabilisation. Although the genes encoding EB proteins are found in all eukaryotic genomes, most studies of them have centred on one or another taxonomic group, without a broad comparative analysis. Here, we present a first phylogenetic analysis and a comparative analysis of domain structures of diatom EB proteins in comparison with other phyla of Chromista, red and green algae, as well as model organisms A. thaliana and H. sapiens. Phylogenetically, diatom EB proteins are separated into six clades, generally corresponding to the phylogeny of their respective organisms. The domain structure of this family is highly variable, but the CH and EBH domains responsible for binding tubulin and other MAPs are mostly conserved. Homologous modelling of the F. cylindrus EB protein shows that conserved motifs of the CH domain are positioned on the protein surface, which is necessary for their functioning. We hypothesise that high variance of the diatom C-terminal domain is caused by previously unknown interactions with a CAP-GLY motif of dynactin subunit p150. Our findings contribute to wider possibilities for further investigations of the cytoskeleton in diatoms.
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Affiliation(s)
- Darya P Petrova
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | - Kirill V Khabudaev
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
| | | | - Yelena V Likhoshway
- Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia.
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Kaczmarska I, Ehrman JM. Enlarge or die! An auxospore perspective on diatom diversification. ORG DIVERS EVOL 2021. [DOI: 10.1007/s13127-020-00476-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Seveno J, Even Y, Le Gac M. Strong constitutive expression divergence among strains but no evidence of differential expression associated with sexual reproduction in Alexandrium minutum. HARMFUL ALGAE 2020; 100:101940. [PMID: 33298362 DOI: 10.1016/j.hal.2020.101940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/16/2020] [Accepted: 11/01/2020] [Indexed: 06/12/2023]
Abstract
Sexual reproduction remains poorly characterized in dinoflagellates. This is especially the case at the molecular level. Here crossing experiments were performed among strains of the toxic dinoflagellate Alexandrium minutum belonging to two genetically divergent groups. Gene expression was compared between sexually compatible and incompatible crosses at the time of gamete fusion and resting cyst (~zygote) formation. Not a single transcript was identified as differentially expressed between compatible and incompatible crosses at these two crucial time points of the dinoflagellate life cycle. However, several thousands of transcripts displayed constitutive expression differences between strains. This was especially the case between the strains belonging to the genetically divergent groups. A few hundreds of transcripts were also identified as differentially expressed between strains belonging to opposite mating types. Some of these transcripts displayed homology with the SxtA protein, known to be involved in saxitoxin production in cyanobacteria, as well as with proteins potentially involved in mating in fungi.
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Affiliation(s)
- Julie Seveno
- Ifremer, DYNECO PELAGOS, 29280 Plouzané, France; Laboratoire Mer Molécule Santé, Le Mans Université, 72000 Le Mans, France
| | - Yasmine Even
- Laboratoire des Sciences de l'Environnement Marin, UMR 6539 CNRS/UBO - Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, 29280 Plouzané, France
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Mating type specific transcriptomic response to sex inducing pheromone in the pennate diatom Seminavis robusta. ISME JOURNAL 2020; 15:562-576. [PMID: 33028976 PMCID: PMC8027222 DOI: 10.1038/s41396-020-00797-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/10/2020] [Accepted: 09/24/2020] [Indexed: 12/14/2022]
Abstract
Sexual reproduction is a fundamental phase in the life cycle of most diatoms. Despite its role as a source of genetic variation, it is rarely reported in natural circumstances and its molecular foundations remain largely unknown. Here, we integrate independent transcriptomic datasets to prioritize genes responding to sex inducing pheromones (SIPs) in the pennate diatom Seminavis robusta. We observe marked gene expression changes associated with SIP treatment in both mating types, including an inhibition of S phase progression, chloroplast division, mitosis, and cell wall formation. Meanwhile, meiotic genes are upregulated in response to SIP, including a sexually induced diatom specific cyclin. Our data further suggest an important role for reactive oxygen species, energy metabolism, and cGMP signaling during the early stages of sexual reproduction. In addition, we identify several genes with a mating type specific response to SIP, and link their expression pattern with physiological specialization, such as the production of the attraction pheromone diproline in mating type − (MT−) and mate-searching behavior in mating type + (MT+). Combined, our results provide a model for early sexual reproduction in pennate diatoms and significantly expand the suite of target genes to detect sexual reproduction events in natural diatom populations.
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