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Grant AR, Johnson KP, Stanley EL, Baldwin-Brown J, Kolenčík S, Allen JM. Rapid Targeted Assembly of the Proteome Reveals Evolutionary Variation of GC Content in Avian Lice. Bioinform Biol Insights 2024; 18:11779322241257991. [PMID: 38860163 PMCID: PMC11163934 DOI: 10.1177/11779322241257991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 05/02/2024] [Indexed: 06/12/2024] Open
Abstract
Nucleotide base composition plays an influential role in the molecular mechanisms involved in gene function, phenotype, and amino acid composition. GC content (proportion of guanine and cytosine in DNA sequences) shows a high level of variation within and among species. Many studies measure GC content in a small number of genes, which may not be representative of genome-wide GC variation. One challenge when assembling extensive genomic data sets for these studies is the significant amount of resources (monetary and computational) associated with data processing, and many bioinformatic tools have not been optimized for resource efficiency. Using a high-performance computing (HPC) cluster, we manipulated resources provided to the targeted gene assembly program, automated target restricted assembly method (aTRAM), to determine an optimum way to run the program to maximize resource use. Using our optimum assembly approach, we assembled and measured GC content of all of the protein-coding genes of a diverse group of parasitic feather lice. Of the 499 426 genes assembled across 57 species, feather lice were GC-poor (mean GC = 42.96%) with a significant amount of variation within and between species (GC range = 19.57%-73.33%). We found a significant correlation between GC content and standard deviation per taxon for overall GC and GC3, which could indicate selection for G and C nucleotides in some species. Phylogenetic signal of GC content was detected in both GC and GC3. This research provides a large-scale investigation of GC content in parasitic lice laying the foundation for understanding the basis of variation in base composition across species.
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Affiliation(s)
- Avery R Grant
- Department of Biology, University of Nevada, Reno, Reno, NV, USA
| | - Kevin P Johnson
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Edward L Stanley
- Department of Natural History, Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
| | | | - Stanislav Kolenčík
- Faculty of Mathematics, Natural Sciences, and Information Technologies, University of Primorska, Koper, Slovenia
| | - Julie M Allen
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
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2
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Shah M, Bornemann TLV, Nuy JK, Hahn MW, Probst AJ, Beisser D, Boenigk J. Genome-resolved metagenomics reveals the effect of nutrient availability on bacterial genomic properties across 44 European freshwater lakes. Environ Microbiol 2024; 26:e16634. [PMID: 38881319 DOI: 10.1111/1462-2920.16634] [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: 12/15/2023] [Accepted: 04/25/2024] [Indexed: 06/18/2024]
Abstract
Understanding intricate microbial interactions in the environment is crucial. This is especially true for the relationships between nutrients and bacteria, as phosphorus, nitrogen and organic carbon availability are known to influence bacterial population dynamics. It has been suggested that low nutrient conditions prompt the evolutionary process of genome streamlining. This process helps conserve scarce nutrients and allows for proliferation. Genome streamlining is associated with genomic properties such as %GC content, genes encoding sigma factors, percent coding regions, gene redundancy, and functional shifts in processes like cell motility and ATP binding cassette transporters, among others. The current study aims to unveil the impact of nutrition on the genome size, %GC content, and functional properties of pelagic freshwater bacteria. We do this at finer taxonomic resolutions for many metagenomically characterized communities. Our study confirms the interplay of trophic level and genomic properties. It also highlights that different nutrient types, particularly phosphorus and nitrogen, impact these properties differently. We observed a covariation of functional traits with genome size. Larger genomes exhibit enriched pathways for motility, environmental interaction, and regulatory genes. ABC transporter genes reflect the availability of nutrients in the environment, with small genomes presumably relying more on metabolites from other organisms. We also discuss the distinct strategies different phyla adopt to adapt to oligotrophic environments. The findings contribute to our understanding of genomic adaptations within complex microbial communities.
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Affiliation(s)
- Manan Shah
- Department of Biodiversity, University of Duisburg-Essen, Essen, Germany
- Environmental Metagenomics, Research Center One Health Ruhr of the University Alliance Ruhr, University of Duisburg-Essen, Essen, Germany
- Department of Engineering and Natural Sciences, Westphalian University of Applied Science, Recklinghausen, Germany
| | - Till L V Bornemann
- Environmental Metagenomics, Research Center One Health Ruhr of the University Alliance Ruhr, University of Duisburg-Essen, Essen, Germany
- Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany
| | - Julia K Nuy
- Environmental Metagenomics, Research Center One Health Ruhr of the University Alliance Ruhr, University of Duisburg-Essen, Essen, Germany
- Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany
| | - Martin W Hahn
- Research Department for Limnology, Universität Innsbruck, Mondsee, Austria
| | - Alexander J Probst
- Environmental Metagenomics, Research Center One Health Ruhr of the University Alliance Ruhr, University of Duisburg-Essen, Essen, Germany
- Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany
| | - Daniela Beisser
- Department of Engineering and Natural Sciences, Westphalian University of Applied Science, Recklinghausen, Germany
- Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany
| | - Jens Boenigk
- Department of Biodiversity, University of Duisburg-Essen, Essen, Germany
- Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany
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3
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Alexander H, Hu SK, Krinos AI, Pachiadaki M, Tully BJ, Neely CJ, Reiter T. Eukaryotic genomes from a global metagenomic data set illuminate trophic modes and biogeography of ocean plankton. mBio 2023; 14:e0167623. [PMID: 37947402 PMCID: PMC10746220 DOI: 10.1128/mbio.01676-23] [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: 06/30/2023] [Accepted: 09/27/2023] [Indexed: 11/12/2023] Open
Abstract
IMPORTANCE Single-celled eukaryotes play ecologically significant roles in the marine environment, yet fundamental questions about their biodiversity, ecological function, and interactions remain. Environmental sequencing enables researchers to document naturally occurring protistan communities, without culturing bias, yet metagenomic and metatranscriptomic sequencing approaches cannot separate individual species from communities. To more completely capture the genomic content of mixed protistan populations, we can create bins of sequences that represent the same organism (metagenome-assembled genomes [MAGs]). We developed the EukHeist pipeline, which automates the binning of population-level eukaryotic and prokaryotic genomes from metagenomic reads. We show exciting insight into what protistan communities are present and their trophic roles in the ocean. Scalable computational tools, like EukHeist, may accelerate the identification of meaningful genetic signatures from large data sets and complement researchers' efforts to leverage MAG databases for addressing ecological questions, resolving evolutionary relationships, and discovering potentially novel biodiversity.
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Affiliation(s)
- Harriet Alexander
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Sarah K. Hu
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Arianna I. Krinos
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge and Woods Hole, Massachusetts, USA
| | - Maria Pachiadaki
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Benjamin J. Tully
- Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Christopher J. Neely
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California, USA
| | - Taylor Reiter
- Population Health and Reproduction, University of California, Davis, Davis, California, USA
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4
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Liu Q, Chen Y, Xu XW. Genomic insight into strategy, interaction and evolution of nitrifiers in metabolizing key labile-dissolved organic nitrogen in different environmental niches. Front Microbiol 2023; 14:1273211. [PMID: 38156017 PMCID: PMC10753782 DOI: 10.3389/fmicb.2023.1273211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 11/09/2023] [Indexed: 12/30/2023] Open
Abstract
Ammonia-oxidizing archaea (AOA) and bacteria (AOB), nitrite-oxidizing bacteria (NOB), and complete ammonia oxidizers (comammox) are responsible for nitrification in nature; however, some groups have been reported to utilize labile-dissolved organic nitrogen (LDON) for satisfying nitrogen demands. To understand the universality of their capacity of LDON metabolism, we collected 70 complete genomes of AOA, AOB, NOB, and comammox from typical environments for exploring their potentials in the metabolism of representative LDON (urea, polyamines, cyanate, taurine, glycine betaine, and methylamine). Genomic analyses showed that urea was the most popular LDON used by nitrifiers. Each group harbored unique urea transporter genes (AOA: dur3 and utp, AOB: utp, and NOB and comammox: urtABCDE and utp) accompanied by urease genes ureABC. The differentiation in the substrate affinity of these transporters implied the divergence of urea utilization efficiency in nitrifiers, potentially driving them into different niches. The cyanate transporter (cynABD and focA/nirC) and degradation (cynS) genes were detected mostly in NOB, indicating their preference for a wide range of nitrogen substrates to satisfy high nitrogen demands. The lack of genes involved in the metabolism of polyamines, taurine, glycine betaine, and methylamines in most of nitrifiers suggested that they were not able to serve as a source of ammonium, only if they were degraded or oxidized extracellularly as previously reported. The phylogenetic analyses assisted with comparisons of GC% and the Codon Adaptation Index between target genes and whole genomes of nitrifiers implied that urea metabolic genes dur3 and ureC in AOA evolved independently from bacteria during the transition from Thaumarchaeota to AOA, while utp in terrestrial AOA was acquired from bacteria via lateral gene transfer (LGT). Cyanate transporter genes cynS and focA/nirC detected only in a terrestrial AOA Candidadus Nitrsosphaera gargensis Ga9.2 could be gained synchronously with Nitrospira of NOB by an ancient LGT. Our results indicated that LDON utilization was a common feature in nitrifiers, but metabolic potentials were different among nitrifiers, possibly being intensely interacted with their niches, survival strategies, and evolutions.
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Affiliation(s)
- Qian Liu
- Donghai Laboratory, Zhoushan, Zhejiang, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Ocean College, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yuhao Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Xue-Wei Xu
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang, China
- Ocean College, Zhejiang University, Hangzhou, Zhejiang, China
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
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5
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Satyam R, Ahmad S, Raza K. Comparative genomic assessment of members of genus Tenacibaculum: an exploratory study. Mol Genet Genomics 2023:10.1007/s00438-023-02031-3. [PMID: 37225902 DOI: 10.1007/s00438-023-02031-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 05/04/2023] [Indexed: 05/26/2023]
Abstract
Tenacibaculosis is an ulcerative skin disorder that affects finfish. It is caused by members of the genus Tenacibaculum, resulting in eccentric behavioural changes, including anorexia, lethargy, and abnormal swimming patterns that often result in mortality. Currently, species suspected of causing fish mortality include T. ovolyticum, T. gallaicum, T. discolor, T. finnmarkense, T. mesophilum, T. soleae, T. dicentrarchi, and T. maritimum. However, pathogenic members and the mechanisms involved in disease causation, progression, and transmission are limited due to the inadequate sequencing efforts in the past decade. In this study, we use a comparative genomics approach to investigate the characteristic features of 26 publicly available genomes of Tenacibaculum and report our observations. We propose the reclassification of "T. litoreum HSC 22" to the singaporense species and assignment of "T. sp. 4G03" to the species discolor (species with quotation marks have not been appropriately named). We also report the co-occurrence of several antimicrobial resistance/virulence genes and genes private to a few members. Finally, we mine several non-B DNA forming regions, operons, tandem repeats, high-confidence putative effector proteins, and sortase that might play a pivotal role in bacterial evolution, transcription, and pathogenesis.
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Affiliation(s)
- Rohit Satyam
- Computational Intelligence and Bioinformatics Laboratory, Department of Computer Science, Jamia Millia Islamia, New Delhi, 110025, India
| | - Shaban Ahmad
- Computational Intelligence and Bioinformatics Laboratory, Department of Computer Science, Jamia Millia Islamia, New Delhi, 110025, India
| | - Khalid Raza
- Computational Intelligence and Bioinformatics Laboratory, Department of Computer Science, Jamia Millia Islamia, New Delhi, 110025, India.
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6
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Chen W, Geng Y, Zhang B, Yan Y, Zhao F, Miao M. Stop or Not: Genome-Wide Profiling of Reassigned Stop Codons in Ciliates. Mol Biol Evol 2023; 40:msad064. [PMID: 36952281 PMCID: PMC10089648 DOI: 10.1093/molbev/msad064] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 02/13/2023] [Accepted: 03/13/2023] [Indexed: 03/24/2023] Open
Abstract
Bifunctional stop codons that have both translation and termination functions in the same species are important for understanding the evolution and function of genetic codes in living organisms. Considering the high frequency of bifunctional codons but limited number of available genomes in ciliates, we de novo sequenced seven representative ciliate genomes to explore the evolutionary history of stop codons. We further propose a stop codon reassignment quantification method (stopCR) that can identify bifunctional codons and measure their frequencies in various eukaryotic organisms. Using our newly developed method, we found two previously undescribed genetic codes, illustrating the prevalence of bifunctional stop codons in ciliates. Overall, evolutionary genomic analyses suggest that gain or loss of reassigned stop codons in ciliates is shaped by their living environment, the eukaryotic release factor 1, and suppressor tRNAs. This study provides novel clues about the functional diversity and evolutionary history of stop codons in eukaryotic organisms.
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Affiliation(s)
- Wenbing Chen
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Yupeng Geng
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, School of Ecology and Environmental Sciences, Yunnan University, Kunming, China
| | - Bing Zhang
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Ying Yan
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Fangqing Zhao
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology, School of Ecology and Environmental Sciences, Yunnan University, Kunming, China
| | - Miao Miao
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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7
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Engelberts JP, Robbins SJ, Herbold CW, Moeller FU, Jehmlich N, Laffy PW, Wagner M, Webster NS. Metabolic reconstruction of the near complete microbiome of the model sponge Ianthella basta. Environ Microbiol 2023; 25:646-660. [PMID: 36480164 PMCID: PMC10947273 DOI: 10.1111/1462-2920.16302] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Abstract
Many marine sponges host highly diverse microbiomes that contribute to various aspects of host health. Although the putative function of individual groups of sponge symbionts has been increasingly described, the extreme diversity has generally precluded in-depth characterization of entire microbiomes, including identification of syntrophic partnerships. The Indo-Pacific sponge Ianthella basta is emerging as a model organism for symbiosis research, hosting only three dominant symbionts: a Thaumarchaeotum, a Gammaproteobacterium, and an Alphaproteobacterium and a range of other low abundance or transitory taxa. Here, we retrieved metagenome assembled genomes (MAGs) representing >90% of I. basta's microbial community, facilitating the metabolic reconstruction of the sponge's near complete microbiome. Through this analysis, we identified metabolic complementarity between microbes, including vitamin sharing, described the importance of low abundance symbionts, and characterized a novel microbe-host attachment mechanism in the Alphaproteobacterium. We further identified putative viral sequences, highlighting the role viruses can play in maintaining symbioses in I. basta through the horizontal transfer of eukaryotic-like proteins, and complemented this data with metaproteomics to identify active metabolic pathways in bacteria, archaea, and viruses. This data provide the framework to adopt I. basta as a model organism for studying host-microbe interactions and provide a basis for in-depth physiological experiments.
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Affiliation(s)
- Joan Pamela Engelberts
- Australian Centre for Ecogenomics, School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - Steven J. Robbins
- Australian Centre for Ecogenomics, School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - Craig W. Herbold
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Florian U. Moeller
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
| | - Nico Jehmlich
- Department of Molecular Systems BiologyHelmholtz‐Centre for Environmental Research – UFZLeipzigGermany
| | - Patrick W. Laffy
- Australian Institute of Marine ScienceTownsvilleQueenslandAustralia
| | - Michael Wagner
- Centre for Microbiology and Environmental Systems Science, Division of Microbial EcologyUniversity of ViennaAustria
- Center for Microbial Communities, Department of Chemistry and BioscienceAalborg UniversityAalborgDenmark
| | - Nicole S. Webster
- Australian Centre for Ecogenomics, School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Australian Institute of Marine ScienceTownsvilleQueenslandAustralia
- Australian Antarctic DivisionKingstonTasmaniaAustralia
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8
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Teng W, Liao B, Chen M, Shu W. Genomic Legacies of Ancient Adaptation Illuminate GC-Content Evolution in Bacteria. Microbiol Spectr 2023; 11:e0214522. [PMID: 36511682 PMCID: PMC9927291 DOI: 10.1128/spectrum.02145-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Bacterial evolution is characterized by strong purifying selection as well as rapid adaptive evolution in changing environments. In this context, the genomic GC content (genomic GC) varies greatly but presents some level of phylogenetic stability, making it challenging to explain based on current hypotheses. To illuminate the evolutionary mechanisms of the genomic GC, we analyzed the base composition and functional inventory of 11,083 representative genomes. A phylogenetically constrained bimodal distribution of the genomic GC, which mainly originated from parallel divergences in the early evolution, was demonstrated. Such variation of the genomic GC can be well explained by DNA replication and repair (DRR), in which multiple pathways correlate with the genomic GC. Furthermore, the biased conservation of various stress-related genes, especially the DRR-related ones, implies distinct adaptive processes in the ancestral lineages of high- or low-GC clades which are likely induced by major environmental changes. Our findings support that the mutational biases resulting from these legacies of ancient adaptation have changed the course of adaptive evolution and generated great variation in the genomic GC. This highlights the importance of indirect effects of natural selection, which indicates a new model for bacterial evolution. IMPORTANCE GC content has been shown to be an important factor in microbial ecology and evolution, and the genomic GC of bacteria can be characterized by great intergenomic heterogeneity, high intragenomic homogeneity, and strong phylogenetic inertia, as well as being associated with the environment. Current hypotheses concerning direct selection or mutational biases cannot well explain these features simultaneously. Our findings of the genomic GC showing that ancient adaptations have transformed the DRR system and that the resulting mutational biases further contributed to a bimodal distribution of it offer a more reasonable scenario for the mechanism. This would imply that, when thinking about the evolution of life, diverse processes of adaptation exist, and combined effects of natural selection should be considered.
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Affiliation(s)
- Wenkai Teng
- School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Bin Liao
- School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Mengyun Chen
- School of Life Sciences, South China Normal University, Guangzhou, Guangdong, China
| | - Wensheng Shu
- School of Life Sciences, South China Normal University, Guangzhou, Guangdong, China
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9
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How Many Factors Influence Genomic GC Content Among Prokaryotes? J Mol Evol 2023; 91:6-9. [PMID: 36370165 DOI: 10.1007/s00239-022-10077-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/04/2022] [Indexed: 11/14/2022]
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10
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Jiang C, Kasai H, Mino S, Romalde JL, Sawabe T. The pan‐genome of Splendidus clade species in the family
Vibrionaceae
: insights into evolution, adaptation, and pathogenicity. Environ Microbiol 2022; 24:4587-4606. [DOI: 10.1111/1462-2920.16209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/13/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Chunqi Jiang
- Laboratory of Microbiology, Faculty of Fisheries Sciences Hokkaido University Hakodate Japan
| | - Hisae Kasai
- Laboratory of Marine Biotechnology and Microbiology, Faculty of Fisheries Sciences Hokkaido University Hakodate Japan
| | - Sayaka Mino
- Laboratory of Microbiology, Faculty of Fisheries Sciences Hokkaido University Hakodate Japan
| | - Jesús L. Romalde
- Departamento de Microbiología y Parasitología, CRETUS & CIBUS‐Facultad de Biología. Universidade de Santiago de Compostela Spain
| | - Tomoo Sawabe
- Laboratory of Microbiology, Faculty of Fisheries Sciences Hokkaido University Hakodate Japan
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11
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Chen Z, Wang X, Song Y, Zeng Q, Zhang Y, Luo H. Prochlorococcus have low global mutation rate and small effective population size. Nat Ecol Evol 2022; 6:183-194. [PMID: 34949817 DOI: 10.1038/s41559-021-01591-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 10/14/2021] [Indexed: 12/27/2022]
Abstract
Prochlorococcus are the most abundant free-living photosynthetic carbon-fixing organisms in the ocean. Prochlorococcus show small genome sizes, low genomic G+C content, reduced DNA repair gene pool and fast evolutionary rates, which are typical features of endosymbiotic bacteria. Nevertheless, their evolutionary mechanisms are believed to be different. Evolution of endosymbiotic bacteria is dominated by genetic drift owing to repeated population bottlenecks, whereas Prochlorococcus are postulated to have extremely large effective population sizes (Ne) and thus drift has rarely been considered. However, accurately extrapolating Ne requires measuring an unbiased global mutation rate through mutation accumulation, which is challenging for Prochlorococcus. Here, we managed this experiment over 1,065 days using Prochlorococcus marinus AS9601, sequenced genomes of 141 mutant lines and determined its mutation rate to be 3.50 × 10-10 per site per generation. Extrapolating Ne additionally requires identifying population boundaries, which we defined using PopCOGenT and over 400 genomes related to AS9601. Accordingly, we calculated its Ne to be 1.68 × 107, which is only reasonably greater than that of endosymbiotic bacteria but surprisingly smaller than that of many free-living bacteria extrapolated using the same approach. Our results therefore suggest that genetic drift is a key driver of Prochlorococcus evolution.
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Affiliation(s)
- Zhuoyu Chen
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Xiaojun Wang
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Yu Song
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Qinglu Zeng
- Department of Ocean Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR.,Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Clear Water Bay, Hong Kong SAR
| | - Yao Zhang
- State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.
| | - Haiwei Luo
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China. .,Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Clear Water Bay, Hong Kong SAR.
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12
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Feng X, Zhang H, Tang J, Luo H. Assessing a Role of Genetic Drift for Deep-Time Evolutionary Events. Methods Mol Biol 2022; 2569:343-359. [PMID: 36083457 DOI: 10.1007/978-1-0716-2691-7_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Effective population size (Ne) determines the amount of genetic diversity and the fate of genetic variants in a species and thus is an essential parameter in evolutionary genetics. There are standard approaches to determine the Ne of evolving species. For example, the long-term Ne of an extant species is calculated based on its unbiased global mutation rate and the neutral genetic diversity of the species. However, approaches for inferring Ne of ancestral lineages are less known. Here, we introduce an evolutionary genetic statistic and an analytical procedure to assess the efficiency of natural selection for deep nodes by calculating rates of nonsynonymous nucleotide substitutions leading to radical (dR) and conservative (dC) amino acid replacements, respectively. Given that radical variants are more likely to be deleterious than conservative ones, an elevated dR/dC ratio in gene families across the genome means an accelerated genome-wide accumulation of the more deleterious type of mutations (i.e., radical variants), which indicates that natural selection is less efficient and genetic drift becomes more powerful. Earlier approaches that calculate dR/dC do not consider the impact of nucleotide composition (G+C content) on the dR/dC result, which is partially accounted for in more recent methods. Here, we use these methods to demonstrate that genetic drift may have driven the early evolution of Prochlorococcus, the most abundant carbon-fixing photosynthetic bacteria in the ocean.
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Affiliation(s)
- Xiaoyuan Feng
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Hao Zhang
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Jijun Tang
- Department of Computer Science and Engineering, University of South Carolina, Columbia, SC, USA
| | - Haiwei Luo
- School of Life Sciences, Earth and Environmental Sciences Programme, and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong SAR, China
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13
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Lin X, McNichol J, Chu X, Qian Y, Luo H. Cryptic niche differentiation of novel sediment ecotypes of Rugeria pomeroyi correlates with nitrate respiration. Environ Microbiol 2021; 24:390-403. [PMID: 34964547 DOI: 10.1111/1462-2920.15882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 10/19/2022]
Abstract
Marine intertidal sediments fluctuate in redox conditions and nutrient availability, and they are also known as an important sink of nitrogen mainly through denitrification, yet how denitrifying bacteria adapt to this dynamic habitat remains largely untapped. Here, we investigated novel intertidal benthic ecotypes of the model pelagic marine bacterium Ruegeria pomeroyi DSS-3 with a population genomic approach. While differing by only 1.3% at the 16S rRNA gene level, members of the intertidal benthic ecotypes are complete denitrifiers whereas the pelagic ecotype representative (DSS-3) is a partial denitrifier lacking a nitrate reductase. The intertidal benthic ecotypes are further differentiated by using non-homologous nitrate reductases and a different set of genes that allow alleviating oxidative stress and acquiring organic substrates. In the presence of nitrate, the two ecotypes showed contrasting growth patterns under initial oxygen concentrations at 1 vol% versus 7 vol% and supplemented with different carbon sources abundant in intertidal sediments. Collectively, this combination of evidence indicates that there are cryptic niches in coastal intertidal sediments that support divergent evolution of denitrifying bacteria. This knowledge will in turn help understand how these benthic environments operate to effectively remove nitrogen.
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Affiliation(s)
- Xingqin Lin
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518000, China
| | - Jesse McNichol
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Xiao Chu
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Yang Qian
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
| | - Haiwei Luo
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518000, China.,Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR
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14
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Feng X, Chu X, Qian Y, Henson MW, Lanclos VC, Qin F, Barnes S, Zhao Y, Thrash JC, Luo H. Mechanisms driving genome reduction of a novel Roseobacter lineage. ISME JOURNAL 2021; 15:3576-3586. [PMID: 34145391 DOI: 10.1038/s41396-021-01036-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/01/2021] [Accepted: 06/04/2021] [Indexed: 01/21/2023]
Abstract
Members of the marine Roseobacter group are key players in the global carbon and sulfur cycles. While over 300 species have been described, only 2% possess reduced genomes (mostly 3-3.5 Mbp) compared to an average roseobacter (>4 Mbp). These taxonomic minorities are phylogenetically diverse but form a Pelagic Roseobacter Cluster (PRC) at the genome content level. Here, we cultivated eight isolates constituting a novel Roseobacter lineage which we named 'CHUG'. Metagenomic and metatranscriptomic read recruitment analyses showed that CHUG members are globally distributed and active in marine pelagic environments. CHUG members possess some of the smallest genomes (~2.6 Mb) among all known roseobacters, but they do not exhibit canonical features of typical bacterioplankton lineages theorized to have undergone genome streamlining processes, like higher coding density, fewer paralogues and rarer pseudogenes. While CHUG members form a genome content cluster with traditional PRC members, they show important differences. Unlike other PRC members, neither the relative abundances of CHUG members nor their relative gene expression levels are correlated with chlorophyll a concentration across the global samples. CHUG members cannot utilize most phytoplankton-derived metabolites or synthesize vitamin B12, a key metabolite mediating the roseobacter-phytoplankton interactions. This combination of features is evidence for the hypothesis that CHUG members may have evolved a free-living lifestyle decoupled from phytoplankton. This ecological transition was accompanied by the loss of signature genes involved in roseobacter-phytoplankton symbiosis, suggesting that relaxation of purifying selection owing to lifestyle shift is likely an important driver of genome reduction in CHUG.
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Affiliation(s)
- Xiaoyuan Feng
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, SAR, Hong Kong.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Xiao Chu
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, SAR, Hong Kong
| | - Yang Qian
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, SAR, Hong Kong
| | - Michael W Henson
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.,Department of Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | - V Celeste Lanclos
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Fang Qin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Shelby Barnes
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Yanlin Zhao
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - J Cameron Thrash
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Haiwei Luo
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, SAR, Hong Kong. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
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15
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Graham ED, Tully BJ. Marine Dadabacteria exhibit genome streamlining and phototrophy-driven niche partitioning. THE ISME JOURNAL 2021; 15:1248-1256. [PMID: 33230264 PMCID: PMC8115339 DOI: 10.1038/s41396-020-00834-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/27/2020] [Accepted: 11/05/2020] [Indexed: 01/29/2023]
Abstract
The remineralization of organic material via heterotrophy in the marine environment is performed by a diverse and varied group of microorganisms that can specialize in the type of organic material degraded and the niche they occupy. The marine Dadabacteria are cosmopolitan in the marine environment and belong to a candidate phylum for which there has not been a comprehensive assessment of the available genomic data to date. Here in, we assess the functional potential of the marine pelagic Dadabacteria in comparison to members of the phylum that originate from terrestrial, hydrothermal, and subsurface environments. Our analysis reveals that the marine pelagic Dadabacteria have streamlined genomes, corresponding to smaller genome sizes and lower nitrogen content of their DNA and predicted proteome, relative to their phylogenetic counterparts. Collectively, the Dadabacteria have the potential to degrade microbial dissolved organic matter, specifically peptidoglycan and phospholipids. The marine Dadabacteria belong to two clades with apparent distinct ecological niches in global metagenomic data: a clade with the potential for photoheterotrophy through the use of proteorhodopsin, present predominantly in surface waters up to 100 m depth; and a clade lacking the potential for photoheterotrophy that is more abundant in the deep photic zone.
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Affiliation(s)
- Elaina D Graham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Benjamin J Tully
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA.
- Center for Dark Energy Biosphere Investigations, University of Southern California, Los Angeles, CA, USA.
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16
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Castillo AI, Almeida RPP. Evidence of gene nucleotide composition favoring replication and growth in a fastidious plant pathogen. G3-GENES GENOMES GENETICS 2021; 11:6170658. [PMID: 33715000 PMCID: PMC8495750 DOI: 10.1093/g3journal/jkab076] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 03/02/2021] [Indexed: 11/13/2022]
Abstract
Nucleotide composition (GC content) varies across bacteria species, genome regions, and specific genes. In Xylella fastidiosa, a vector-borne fastidious plant pathogen infecting multiple crops, GC content ranges between ∼51-52%; however, these values were gathered using limited genomic data. We evaluated GC content variations across X. fastidiosa subspecies fastidiosa (N = 194), subsp. pauca (N = 107), and subsp. multiplex (N = 39). Genomes were classified based on plant host and geographic origin; individual genes within each genome were classified based on gene function, strand, length, ortholog group, Core vs. Accessory, and Recombinant vs. Non-recombinant. GC content was calculated for each gene within each evaluated genome. The effects of genome and gene level variables were evaluated with a mixed effect ANOVA, and the marginal-GC content was calculated for each gene. Also, the correlation between gene-specific GC content vs. natural selection (dN/dS) and recombination/mutation (r/m) was estimated. Our analyses show that intra-genomic changes in nucleotide composition in X. fastidiosa are small and influenced by multiple variables. Higher AT-richness is observed in genes involved in replication and translation, and genes in the leading strand. In addition, we observed a negative correlation between high-AT and dN/dS in subsp. pauca. The relationship between recombination and GC content varied between core and accessory genes. We hypothesize that distinct evolutionary forces and energetic constraints both drive and limit these small variations in nucleotide composition.
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Affiliation(s)
- Andreina I Castillo
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
| | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720, USA
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17
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Abstract
As the most abundant bacteria in oceans, the Pelagibacterales order (here SAR11) plays an important role in the global carbon cycle, but the study of the evolutionary forces driving its evolution has lagged considerably due to the inherent difficulty of obtaining pure cultures. Multiple evolutionary models have been proposed to explain the diversification of distinct lineages within a population; however, the identification of many of these patterns in natural populations remains mostly enigmatic. We have used a metagenomic approach to explore microdiversity patterns in their natural habitats. Comparison with a collection of bacterial and archaeal groups from the same environments shows that SAR11 populations have a different evolutionary regime, where multiple genotypes coexist within the same population and remain stable over time. Widespread homologous recombination could be one of the main driving factors of this homogenization. The SAR11 clade of Alphaproteobacteria is the most abundant group of planktonic cells in the near-surface epipelagic waters of the ocean, but the mechanisms underlying its exceptional success have not been fully elucidated. Here, we applied a metagenomic approach to explore microdiversity patterns by measuring the accumulation of synonymous and nonsynonymous mutations as well as homologous recombination in populations of SAR11 from different aquatic habitats (marine epipelagic, bathypelagic, and surface freshwater). The patterns of mutation accumulation and recombination were compared to those of other groups of representative marine microbes with multiple ecological strategies that share the same marine habitat, namely, Cyanobacteria (Prochlorococcus and Synechococcus), Archaea (“Candidatus Nitrosopelagicus” and Marine Group II Thalassoarchaea), and some heterotrophic marine bacteria (Alteromonas and Erythrobacter). SAR11 populations showed widespread recombination among distantly related members, preventing divergence leading to a genetically stable population. Moreover, their high intrapopulation sequence diversity with an enrichment in synonymous replacements supports the idea of a very ancient divergence and the coexistence of multiple different clones. However, other microbes analyzed seem to follow different evolutionary dynamics where processes of diversification driven by geographic and ecological instability produce a higher number of nonsynonymous replacements and lower intrapopulation sequence diversity. Together, these data shed light on some of the evolutionary and ecological processes that lead to the large genomic diversity in SAR11. Furthermore, this approach can be applied to other similar microbes that are difficult to culture in the laboratory, but abundant in nature, to investigate the underlying dynamics of their genomic evolution. IMPORTANCE As the most abundant bacteria in oceans, the Pelagibacterales order (here SAR11) plays an important role in the global carbon cycle, but the study of the evolutionary forces driving its evolution has lagged considerably due to the inherent difficulty of obtaining pure cultures. Multiple evolutionary models have been proposed to explain the diversification of distinct lineages within a population; however, the identification of many of these patterns in natural populations remains mostly enigmatic. We have used a metagenomic approach to explore microdiversity patterns in their natural habitats. Comparison with a collection of bacterial and archaeal groups from the same environments shows that SAR11 populations have a different evolutionary regime, where multiple genotypes coexist within the same population and remain stable over time. Widespread homologous recombination could be one of the main driving factors of this homogenization.
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18
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Pyropia yezoensis genome reveals diverse mechanisms of carbon acquisition in the intertidal environment. Nat Commun 2020; 11:4028. [PMID: 32788591 PMCID: PMC7423979 DOI: 10.1038/s41467-020-17689-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 07/09/2020] [Indexed: 12/15/2022] Open
Abstract
Changes in atmospheric CO2 concentration have played a central role in algal and plant adaptation and evolution. The commercially important red algal genus, Pyropia (Bangiales) appears to have responded to inorganic carbon (Ci) availability by evolving alternating heteromorphic generations that occupy distinct habitats. The leafy gametophyte inhabits the intertidal zone that undergoes frequent emersion, whereas the sporophyte conchocelis bores into mollusk shells. Here, we analyze a high-quality genome assembly of Pyropia yezoensis to elucidate the interplay between Ci availability and life cycle evolution. We find horizontal gene transfers from bacteria and expansion of gene families (e.g. carbonic anhydrase, anti-oxidative related genes), many of which show gametophyte-specific expression or significant up-regulation in gametophyte in response to dehydration. In conchocelis, the release of HCO3- from shell promoted by carbonic anhydrase provides a source of Ci. This hypothesis is supported by the incorporation of 13C isotope by conchocelis when co-cultured with 13C-labeled CaCO3. The nori producing seaweed Pyropia yezoensis has heteromorphic generations that occupy distinct habitats. Here, via genome assembly, transcriptome analysis, and 13 C isotope labeling, the authors show the interplay between inorganic carbon availability and life cycle evolution in the intertidal environment.
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19
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Selection for Reducing Energy Cost of Protein Production Drives the GC Content and Amino Acid Composition Bias in Gene Transfer Agents. mBio 2020; 11:mBio.01206-20. [PMID: 32665274 PMCID: PMC7360931 DOI: 10.1128/mbio.01206-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Kin selection and group selection remain controversial topics in evolutionary biology. We argue that these types of selection are likely to operate in bacterial populations by showing that bacterial gene transfer agents (GTAs), but not related viruses, evolve under conditions of positive selection for the reduction of the energy cost of GTA particle production. We hypothesize that GTAs are dedicated devices mediating the survival of bacteria under conditions of nutrient limitation. The benefits conferred by GTAs under nutritional stress conditions appear to include horizontal dissemination of genes that could provide bacteria with enhanced capabilities for nutrient utilization and increases of nutrient availability occurring through the lysis of GTA-producing bacteria. Gene transfer agents (GTAs) are virus-like elements integrated into bacterial genomes, particularly, those of Alphaproteobacteria. The GTAs can be induced under conditions of nutritional stress, incorporate random fragments of bacterial DNA into miniphage particles, lyse the host cells, and infect neighboring bacteria, thus enhancing horizontal gene transfer. We show that GTA genes evolve under conditions of pronounced positive selection for the reduction of the energy cost of protein production as shown by comparison of the amino acid compositions with those of both homologous viral genes and host genes. The energy saving in GTA genes is comparable to or even more pronounced than that in the genes encoding the most abundant, essential bacterial proteins. In cases in which viruses acquire genes from GTAs, the bias in amino acid composition disappears in the course of evolution, showing that reduction of the energy cost of protein production is an important factor of evolution of GTAs but not bacterial viruses. These findings strongly suggest that GTAs represent bacterial adaptations rather than selfish, virus-like elements. Because GTA production kills the host cell and does not propagate the GTA genome, it appears likely that the GTAs are retained in the course of evolution via kin or group selection. Therefore, we hypothesize that GTAs facilitate the survival of bacterial populations under energy-limiting conditions through the spread of metabolic and transport capabilities via horizontal gene transfer and increases in nutrient availability resulting from the altruistic suicide of GTA-producing cells.
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20
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Haro-Moreno JM, Rodriguez-Valera F, Rosselli R, Martinez-Hernandez F, Roda-Garcia JJ, Gomez ML, Fornas O, Martinez-Garcia M, López-Pérez M. Ecogenomics of the SAR11 clade. Environ Microbiol 2019; 22:1748-1763. [PMID: 31840364 PMCID: PMC7318151 DOI: 10.1111/1462-2920.14896] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/25/2019] [Accepted: 12/11/2019] [Indexed: 12/23/2022]
Abstract
Members of the SAR11 clade, despite their high abundance, are often poorly represented by metagenome‐assembled genomes. This fact has hampered our knowledge about their ecology and genetic diversity. Here we examined 175 SAR11 genomes, including 47 new single‐amplified genomes. The presence of the first genomes associated with subclade IV suggests that, in the same way as subclade V, they might be outside the proposed Pelagibacterales order. An expanded phylogenomic classification together with patterns of metagenomic recruitment at a global scale have allowed us to define new ecogenomic units of classification (genomospecies), appearing at different, and sometimes restricted, metagenomic data sets. We detected greater microdiversity across the water column at a single location than in samples collected from similar depth across the global ocean, suggesting little influence of biogeography. In addition, pangenome analysis revealed that the flexible genome was essential to shape genomospecies distribution. In one genomospecies preferentially found within the Mediterranean, a set of genes involved in phosphonate utilization was detected. While another, with a more cosmopolitan distribution, was unique in having an aerobic purine degradation pathway. Together, these results provide a glimpse of the enormous genomic diversity within this clade at a finer resolution than the currently defined clades.
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Affiliation(s)
- Jose M Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan 03550, Alicante, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan 03550, Alicante, Spain.,Laboratory for Theoretical and Computer Research on Biological Macromolecules and Genomes, Moscow Institute of Physics and Technology, 141701, Dolgoprudny, Russia
| | - Riccardo Rosselli
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan 03550, Alicante, Spain.,Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Texel, The Netherlands
| | | | - Juan J Roda-Garcia
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan 03550, Alicante, Spain
| | - Monica Lluesma Gomez
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Oscar Fornas
- Flow Cytometry Unit, Pompeu Fabra University (UPF) and Centre for Genomic Regulation (CRG), The Barcelona Institute for Sciences and Technology (BIST), Barcelona, Spain
| | - Manuel Martinez-Garcia
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan 03550, Alicante, Spain
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21
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Salcher MM, Schaefle D, Kaspar M, Neuenschwander SM, Ghai R. Evolution in action: habitat transition from sediment to the pelagial leads to genome streamlining in Methylophilaceae. THE ISME JOURNAL 2019; 13:2764-2777. [PMID: 31292537 PMCID: PMC6794327 DOI: 10.1038/s41396-019-0471-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 12/15/2022]
Abstract
The most abundant aquatic microbes are small in cell and genome size. Genome-streamlining theory predicts gene loss caused by evolutionary selection driven by environmental factors, favouring superior competitors for limiting resources. However, evolutionary histories of such abundant, genome-streamlined microbes remain largely unknown. Here we reconstruct the series of steps in the evolution of some of the most abundant genome-streamlined microbes in freshwaters ("Ca. Methylopumilus") and oceans (marine lineage OM43). A broad genomic spectrum is visible in the family Methylophilaceae (Betaproteobacteria), from sediment microbes with medium-sized genomes (2-3 Mbp genome size), an occasionally blooming pelagic intermediate (1.7 Mbp), and the most reduced pelagic forms (1.3 Mbp). We show that a habitat transition from freshwater sediment to the relatively oligotrophic pelagial was accompanied by progressive gene loss and adaptive gains. Gene loss has mainly affected functions not necessarily required or advantageous in the pelagial or is encoded by redundant pathways. Likewise, we identified genes providing adaptations to oligotrophic conditions that have been transmitted horizontally from pelagic freshwater microbes. Remarkably, the secondary transition from the pelagial of lakes to the oceans required only slight modifications, i.e., adaptations to higher salinity, gained via horizontal gene transfer from indigenous microbes. Our study provides first genomic evidence of genome reduction taking place during habitat transitions. In this regard, the family Methylophilaceae is an exceptional model for tracing the evolutionary history of genome streamlining as such a collection of evolutionarily related microbes from different habitats is rare in the microbial world.
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Affiliation(s)
- Michaela M Salcher
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, Na Sádkách 7, 37005, České Budějovice, Czech Republic.
- Limnological Station, Institute of Plant and Microbial Biology, University of Zurich, Seestrasse 187, 8802, Kilchberg, Switzerland.
| | - Daniel Schaefle
- Limnological Station, Institute of Plant and Microbial Biology, University of Zurich, Seestrasse 187, 8802, Kilchberg, Switzerland
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 28/30, 8006, Zurich, Switzerland
| | - Melissa Kaspar
- Limnological Station, Institute of Plant and Microbial Biology, University of Zurich, Seestrasse 187, 8802, Kilchberg, Switzerland
| | - Stefan M Neuenschwander
- Limnological Station, Institute of Plant and Microbial Biology, University of Zurich, Seestrasse 187, 8802, Kilchberg, Switzerland
- Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001, Bern, Switzerland
| | - Rohit Ghai
- Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS, Na Sádkách 7, 37005, České Budějovice, Czech Republic
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22
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Red Sea SAR11 and Prochlorococcus Single-Cell Genomes Reflect Globally Distributed Pangenomes. Appl Environ Microbiol 2019; 85:AEM.00369-19. [PMID: 31028022 DOI: 10.1128/aem.00369-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/19/2019] [Indexed: 11/20/2022] Open
Abstract
Evidence suggests many marine bacteria are cosmopolitan, with widespread but sparse strains poised to seed abundant populations under conducive growth conditions. However, studies supporting this "microbial seed bank" hypothesis have analyzed taxonomic marker genes rather than whole genomes/metagenomes, leaving open the possibility that disparate ocean regions harbor endemic gene content. The Red Sea is isolated geographically from the rest of the ocean and has a combination of high irradiance, high temperature, and high salinity that is unique among the oceans; we therefore asked whether it harbors endemic gene content. We sequenced and assembled single-cell genomes of 21 SAR11 (subclades Ia, Ib, Id, and II) and 5 Prochlorococcus (ecotype HLII) samples from the Red Sea and combined them with globally sourced reference genomes to cluster genes into ortholog groups (OGs). Ordination of OG composition could distinguish clades, including phylogenetically cryptic Prochlorococcus ecotypes LLII and LLIII. Compared with reference genomes, 1% of Prochlorococcus and 17% of SAR11 OGs were unique to the Red Sea genomes (RS-OGs). Most (83%) RS-OGs had no annotated function, but 65% of RS-OGs were expressed in diel Red Sea metatranscriptomes, suggesting they are functional. Searching Tara Oceans metagenomes, RS-OGs were as likely to be found as non-RS-OGs; nevertheless, Red Sea and other warm samples could be distinguished from cooler samples using the relative abundances of OGs. The results suggest that the prevalence of OGs in these surface ocean bacteria is largely cosmopolitan, with differences in population metagenomes manifested by differences in relative abundance rather than complete presence/absence of OGs.IMPORTANCE Studies have shown that as we sequence seawater from a selected environment deeper and deeper, we approach finding every bacterial taxon known for the ocean as a whole. However, such studies have focused on taxonomic marker genes rather than on whole genomes, raising the possibility that the lack of endemism results from the method of investigation. We took a geographically isolated water body, the Red Sea, and sequenced single cells from it. We compared those single-cell genomes to available genomes from around the ocean and to ocean-spanning metagenomes. We showed that gene ortholog groups found in Red Sea genomes but not in other genomes are nevertheless common across global ocean metagenomes. These results suggest that Baas Becking's hypothesis "everything is everywhere, but the environment selects" also applies to gene ortholog groups. This widely dispersed functional diversity may give oceanic microbial communities the functional capacity to respond rapidly to changing conditions.
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23
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Becker JW, Hogle SL, Rosendo K, Chisholm SW. Co-culture and biogeography of Prochlorococcus and SAR11. THE ISME JOURNAL 2019; 13:1506-1519. [PMID: 30742057 PMCID: PMC6775983 DOI: 10.1038/s41396-019-0365-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/03/2019] [Accepted: 01/18/2019] [Indexed: 01/07/2023]
Abstract
Prochlorococcus and SAR11 are among the smallest and most abundant organisms on Earth. With a combined global population of about 2.7 × 1028 cells, they numerically dominate bacterioplankton communities in oligotrophic ocean gyres and yet they have never been grown together in vitro. Here we describe co-cultures of Prochlorococcus and SAR11 isolates representing both high- and low-light adapted clades. We examined: (1) the influence of Prochlorococcus on the growth of SAR11 and vice-versa, (2) whether Prochlorococcus can meet specific nutrient requirements of SAR11, and (3) how co-culture dynamics vary when Prochlorococcus is grown with SAR11 compared with sympatric copiotrophic bacteria. SAR11 grew 15-70% faster in co-culture with Prochlorococcus, while the growth of the latter was unaffected. When Prochlorococcus populations entered stationary phase, this commensal relationship rapidly became amensal, as SAR11 abundances decreased dramatically. In parallel experiments with copiotrophic bacteria; however, the heterotrophic partner increased in abundance as Prochlorococcus densities leveled off. The presence of Prochlorococcus was able to meet SAR11's central requirement for organic carbon, but not reduced sulfur. Prochlorococcus strain MIT9313, but not MED4, could meet the unique glycine requirement of SAR11, which could be due to the production and release of glycine betaine by MIT9313, as supported by comparative genomic evidence. Our findings also suggest, but do not confirm, that Prochlorococcus MIT9313 may compete with SAR11 for the uptake of 3-dimethylsulfoniopropionate (DMSP). To give our results an ecological context, we assessed the relative contribution of Prochlorococcus and SAR11 genome equivalents to those of identifiable bacteria and archaea in over 800 marine metagenomes. At many locations, more than half of the identifiable genome equivalents in the euphotic zone belonged to Prochlorococcus and SAR11 - highlighting the biogeochemical potential of these two groups.
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Affiliation(s)
- Jamie W Becker
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Biology, Haverford College, Haverford, PA, USA.
| | - Shane L Hogle
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kali Rosendo
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sallie W Chisholm
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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24
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Castillo AI, Nelson ADL, Lyons E. Tail Wags the Dog? Functional Gene Classes Driving Genome-Wide GC Content in Plasmodium spp. Genome Biol Evol 2019; 11:497-507. [PMID: 30689842 PMCID: PMC6385630 DOI: 10.1093/gbe/evz015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2019] [Indexed: 01/16/2023] Open
Abstract
Plasmodium parasites are valuable models to understand how nucleotide composition affects mutation, diversification, and adaptation. No other observed eukaryotes have undergone such large changes in genomic Guanine-Cytosine (GC) content as seen in the genus Plasmodium (∼30% within 35-40 Myr). Although mutational biases are known to influence GC content in the human-infective Plasmodium vivax and Plasmodium falciparum; no study has addressed how different gene functional classes contribute to genus-wide compositional changes, or if Plasmodium GC content variation is driven by natural selection. Here, we tested the hypothesis that certain gene processes and functions drive variation in global GC content between Plasmodium species. We performed a large-scale comparative genomic analysis using the genomes and predicted genes of 17 Plasmodium species encompassing a wide genomic GC content range. Genic GC content was sorted and divided into ten equally sized quantiles that were then assessed for functional enrichment classes. In agreement that selection on gene classes may drive genomic GC content, trans-membrane proteins were enriched within extreme GC content quantiles (Q1 and Q10). Specifically, variant surface antigens, which primarily interact with vertebrate immune systems, showed skewed GC content distributions compared with other trans-membrane proteins. Although a definitive causation linking GC content, expression, and positive selection within variant surface antigens from Plasmodium vivax, Plasmodium berghei, and Plasmodium falciparum could not be established, we found that regardless of genomic nucleotide composition, genic GC content and expression were positively correlated during trophozoite stages. Overall, these data suggest that, alongside mutational biases, functional protein classes drive Plasmodium GC content change.
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Affiliation(s)
- Andreina I Castillo
- School of Environmental Science, Policy, and Management, University of California, Berkeley
| | | | - Eric Lyons
- BIO5 Institute, School of Plant Sciences, University of Arizona
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Zhang H, Yoshizawa S, Sun Y, Huang Y, Chu X, González JM, Pinhassi J, Luo H. Repeated evolutionary transitions of flavobacteria from marine to non-marine habitats. Environ Microbiol 2019; 21:648-666. [PMID: 30565818 DOI: 10.1111/1462-2920.14509] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/14/2018] [Accepted: 12/14/2018] [Indexed: 01/26/2023]
Abstract
The taxonomy of marine and non-marine organisms rarely overlap, but the mechanisms underlying this distinction are often unknown. Here, we predicted three major ocean-to-land transitions in the evolutionary history of Flavobacteriaceae, a family known for polysaccharide and peptide degradation. These unidirectional transitions were associated with repeated losses of marine signature genes and repeated gains of non-marine adaptive genes. This included various Na+ -dependent transporters, osmolyte transporters and glycoside hydrolases (GH) for sulfated polysaccharide utilization in marine descendants, and in non-marine descendants genes for utilizing the land plant material pectin and genes facilitating terrestrial host interactions. The K+ scavenging ATPase was repeatedly gained whereas the corresponding low-affinity transporter repeatedly lost upon transitions, reflecting K+ ions are less available to non-marine bacteria. Strikingly, the central metabolism Na+ -translocating NADH: quinone dehydrogenase gene was repeatedly gained in marine descendants, whereas the H+ -translocating counterpart was repeatedly gained in non-marine lineages. Furthermore, GH genes were depleted in isolates colonizing animal hosts but abundant in bacteria inhabiting other non-marine niches; thus relative abundances of GH versus peptidase genes among Flavobacteriaceae lineages were inconsistent with the marine versus non-marine dichotomy. We suggest that phylogenomic analyses can cast novel light on mechanisms explaining the distribution and ecology of key microbiome components.
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Affiliation(s)
- Hao Zhang
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Susumu Yoshizawa
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Ying Sun
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Yongjie Huang
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Xiao Chu
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - José M González
- Department of Microbiology, University of La Laguna, La Laguna, ES-38200, Spain
| | - Jarone Pinhassi
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, SE-39182, Sweden
| | - Haiwei Luo
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
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Haro-Moreno JM, López-Pérez M, de la Torre JR, Picazo A, Camacho A, Rodriguez-Valera F. Fine metagenomic profile of the Mediterranean stratified and mixed water columns revealed by assembly and recruitment. MICROBIOME 2018; 6:128. [PMID: 29991350 PMCID: PMC6040077 DOI: 10.1186/s40168-018-0513-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/02/2018] [Indexed: 05/07/2023]
Abstract
BACKGROUND The photic zone of aquatic habitats is subjected to strong physicochemical gradients. To analyze the fine-scale variations in the marine microbiome, we collected seven samples from a single offshore location in the Mediterranean at 15 m depth intervals during a period of strong stratification, as well as two more samples during the winter when the photic water column was mixed. We were able to recover 94 new metagenome-assembled genomes (MAGs) from these metagenomes and examine the distribution of key marine microbes within the photic zone using metagenomic recruitment. RESULTS Our results showed significant differences in the microbial composition of different layers within the stratified photic water column. The majority of microorganisms were confined to discreet horizontal layers of no more than 30 m (stenobathic). Only a few such as members of the SAR11 clade appeared at all depths (eurybathic). During the winter mixing period, only some groups of bloomers such as Pseudomonas were favored. Although most microbes appeared in both seasons, some groups like the SAR116 clade and some Bacteroidetes and Verrucomicrobia seemed to disappear during the mixing period. Furthermore, we found that some microbes previously considered seasonal (e.g., Archaea or Actinobacteria) were living in deeper layers within the photic zone during the stratification period. A strong depth-related specialization was detected, not only at the taxonomic level but also at the functional level, even within the different clades, for the manipulation and uptake of specific polysaccharides. Rhodopsin sequences (green or blue) also showed narrow depth distributions that correlated with the taxonomy of the microbe in which they were found but not with depth. CONCLUSIONS Although limited to a single location in the Mediterranean, this study has profound implications for our understanding of how marine microbial communities vary with depth within the photic zone when stratified. Our results highlight the importance of collecting samples at different depths in the water column when comparing seasonal variations and have important ramifications for global marine studies that most often take samples from only one single depth. Furthermore, our perspective and approaches (metagenomic assembly and recruitment) are broadly applicable to other metagenomic studies.
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Affiliation(s)
- Jose M Haro-Moreno
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain
| | - Mario López-Pérez
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain
| | - José R de la Torre
- Department of Biology, San Francisco State University, San Francisco, CA, 94132, USA
| | - Antonio Picazo
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Burjassot, E-46100, Valencia, Spain
| | - Antonio Camacho
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Burjassot, E-46100, Valencia, Spain
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, Apartado 18, San Juan de Alicante, 03550, Alicante, Spain.
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Homologous Recombination in Core Genomes Facilitates Marine Bacterial Adaptation. Appl Environ Microbiol 2018; 84:AEM.02545-17. [PMID: 29572211 DOI: 10.1128/aem.02545-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/20/2018] [Indexed: 01/01/2023] Open
Abstract
Acquisition of ecologically relevant genes is common among ocean bacteria, but whether it has a major impact on genome evolution in marine environments remains unknown. Here, we analyzed the core genomes of 16 phylogenetically diverse and ecologically relevant bacterioplankton lineages, each consisting of up to five genomes varying at the strain level. Statistical approaches identified from each lineage up to ∼50 loci showing anomalously high divergence at synonymous sites, which is best explained by recombination with distantly related organisms. The enriched gene categories in these outlier loci match well with the characteristics previously identified as the key phenotypes of these lineages. Examples are antibiotic synthesis and detoxification in Phaeobacter inhibens, exopolysaccharide production in Alteromonas macleodii, hydrocarbon degradation in Marinobacter hydrocarbonoclasticus, and cold adaptation in Pseudoalteromonas haloplanktis Intriguingly, the outlier loci feature polysaccharide catabolism in Cellulophaga baltica but not in Cellulophaga lytica, consistent with their primary habitat preferences in macroalgae and beach sands, respectively. Likewise, analysis of Prochlorococcus showed that photosynthesis-related genes listed in the outlier loci are found only in the high-light-adapted ecotype and not in the low-light adapted ecotype. These observations strongly suggest that recombination with distant relatives is a key mechanism driving the ecological diversification among marine bacterial lineages.IMPORTANCE Acquisition of new metabolic genes has been known as an important mechanism driving bacterial evolution and adaptation in the ocean, but acquisition of novel alleles of existing genes and its potential ecological role have not been examined. Guided by population genetic theories, our genomic analysis showed that divergent allele acquisition is prevalent in phylogenetically diverse marine bacterial lineages and that the affected loci often encode metabolic functions that underlie the known ecological roles of the lineages under study.
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28
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Carbon limitation drives GC content evolution of a marine bacterium in an individual-based genome-scale model. ISME JOURNAL 2018; 12:1180-1187. [PMID: 29330536 DOI: 10.1038/s41396-017-0023-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 11/14/2017] [Accepted: 11/21/2017] [Indexed: 01/13/2023]
Abstract
An important unanswered question in evolutionary genomics is the source of considerable variation of genomic base composition (GC content) even among organisms that share one habitat. Evolution toward GC-poor genomes has been considered a major adaptive pathway in the oligotrophic ocean, but GC-rich bacteria are also prevalent and highly successful in this environment. We quantify the contribution of multiple factors to the change of genomic GC content of Ruegeria pomeroyi DSS-3, a representative and GC-rich member in the globally abundant Roseobacter clade, using an agent-based model. The model simulates 2 × 108 cells, which allows random genetic drift to act in a realistic manner. Each cell has a whole genome subject to base-substitution mutation and recombination, which affect the carbon and nitrogen requirements of DNA and protein pools. Nonsynonymous changes can be functionally deleterious. Together, these factors affect the growth and fitness. Simulations show that experimentally determined mutation bias toward GC is not sufficient to build the GC-rich genome of DSS-3. While nitrogen availability has been repeatedly hypothesized to drive the evolution of GC content in marine bacterioplankton, our model instead predicts that DSS-3 and its ancestors have been evolving in environments primarily limited by carbon.
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29
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Clifford EL, Hansell DA, Varela MM, Nieto‐Cid M, Herndl GJ, Sintes E. Crustacean zooplankton release copious amounts of dissolved organic matter as taurine in the ocean. LIMNOLOGY AND OCEANOGRAPHY 2017; 62:2745-2758. [PMID: 29242669 PMCID: PMC5724677 DOI: 10.1002/lno.10603] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 04/30/2017] [Accepted: 05/08/2017] [Indexed: 05/10/2023]
Abstract
Taurine (Tau), an amino acid-like compound, is present in almost all marine metazoans including crustacean zooplankton. It plays an important physiological role in these organisms and is released into the ambient water throughout their life cycle. However, limited information is available on the release rates by marine organisms, the concentrations and turnover of Tau in the ocean. We determined dissolved free Tau concentrations throughout the water column and its release by abundant crustacean mesozooplankton at two open ocean sites (Gulf of Alaska and North Atlantic). At both locations, the concentrations of dissolved free Tau were in the low nM range (up to 15.7 nM) in epipelagic waters, declining sharply in the mesopelagic to about 0.2 nM and remaining fairly stable throughout the bathypelagic waters. Pacific amphipod-copepod assemblages exhibited lower dissolved free Tau release rates per unit biomass (0.8 ± 0.4 μmol g-1 C-biomass h-1) than Atlantic copepods (ranging between 1.3 ± 0.4 μmol g-1 C-biomass h-1 and 9.5 ± 2.1 μmol g-1 C-biomass h-1), in agreement with the well-documented inverse relationship between biomass-normalized excretion rates and body size. Our results indicate that crustacean zooplankton might contribute significantly to the dissolved organic matter flux in marine ecosystems via dissolved free Tau release. Based on the release rates and assuming steady state dissolved free Tau concentrations, turnover times of dissolved free Tau range from 0.05 d to 2.3 d in the upper water column and are therefore similar to those of dissolved free amino acids. This rapid turnover indicates that dissolved free Tau is efficiently consumed in oceanic waters, most likely by heterotrophic bacteria.
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Affiliation(s)
- Elisabeth L. Clifford
- Department of Limnology and Bio‐OceanographyCenter of Ecology, University of ViennaViennaAustria
| | | | - Marta M. Varela
- Centro Oceanográfico de A CoruñaIEO, Instituto Español de OceanografíaA CoruñaSpain
| | - Mar Nieto‐Cid
- CSIC, Instituto de Investigaciones Marinas de VigoVigoSpain
| | - Gerhard J. Herndl
- Department of Limnology and Bio‐OceanographyCenter of Ecology, University of ViennaViennaAustria
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht UniversityDen BurgThe Netherlands
| | - Eva Sintes
- Department of Limnology and Bio‐OceanographyCenter of Ecology, University of ViennaViennaAustria
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30
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Neuenschwander SM, Ghai R, Pernthaler J, Salcher MM. Microdiversification in genome-streamlined ubiquitous freshwater Actinobacteria. ISME JOURNAL 2017; 12:185-198. [PMID: 29027997 DOI: 10.1038/ismej.2017.156] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/03/2017] [Accepted: 06/28/2017] [Indexed: 01/08/2023]
Abstract
Actinobacteria of the acI lineage are the most abundant microbes in freshwater systems, but there are so far no pure living cultures of these organisms, possibly because of metabolic dependencies on other microbes. This, in turn, has hampered an in-depth assessment of the genomic basis for their success in the environment. Here we present genomes from 16 axenic cultures of acI Actinobacteria. The isolates were not only of minute cell size, but also among the most streamlined free-living microbes, with extremely small genome sizes (1.2-1.4 Mbp) and low genomic GC content. Genome reduction in these bacteria might have led to auxotrophy for various vitamins, amino acids and reduced sulphur sources, thus creating dependencies to co-occurring organisms (the 'Black Queen' hypothesis). Genome analyses, moreover, revealed a surprising degree of inter- and intraspecific diversity in metabolic pathways, especially of carbohydrate transport and metabolism, and mainly encoded in genomic islands. The striking genotype microdiversification of acI Actinobacteria might explain their global success in highly dynamic freshwater environments with complex seasonal patterns of allochthonous and autochthonous carbon sources. We propose a new order within Actinobacteria ('Candidatus Nanopelagicales') with two new genera ('Candidatus Nanopelagicus' and 'Candidatus Planktophila') and nine new species.
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Affiliation(s)
- Stefan M Neuenschwander
- Limnological Station, Institute of Microbial and Plant Biology, University of Zurich, Zurich, Switzerland
| | - Rohit Ghai
- Institute of Hydrobiology, Biology Centre CAS, Ceske Budejovice, Czech Republic
| | - Jakob Pernthaler
- Limnological Station, Institute of Microbial and Plant Biology, University of Zurich, Zurich, Switzerland
| | - Michaela M Salcher
- Limnological Station, Institute of Microbial and Plant Biology, University of Zurich, Zurich, Switzerland.,Institute of Hydrobiology, Biology Centre CAS, Ceske Budejovice, Czech Republic
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31
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Simon M, Scheuner C, Meier-Kolthoff JP, Brinkhoff T, Wagner-Döbler I, Ulbrich M, Klenk HP, Schomburg D, Petersen J, Göker M. Phylogenomics of Rhodobacteraceae reveals evolutionary adaptation to marine and non-marine habitats. THE ISME JOURNAL 2017; 11:1483-1499. [PMID: 28106881 PMCID: PMC5437341 DOI: 10.1038/ismej.2016.198] [Citation(s) in RCA: 209] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/29/2016] [Accepted: 11/19/2016] [Indexed: 12/31/2022]
Abstract
Marine Rhodobacteraceae (Alphaproteobacteria) are key players of biogeochemical cycling, comprise up to 30% of bacterial communities in pelagic environments and are often mutualists of eukaryotes. As 'Roseobacter clade', these 'roseobacters' are assumed to be monophyletic, but non-marine Rhodobacteraceae have not yet been included in phylogenomic analyses. Therefore, we analysed 106 genome sequences, particularly emphasizing gene sampling and its effect on phylogenetic stability, and investigated relationships between marine versus non-marine habitat, evolutionary origin and genomic adaptations. Our analyses, providing no unequivocal evidence for the monophyly of roseobacters, indicate several shifts between marine and non-marine habitats that occurred independently and were accompanied by characteristic changes in genomic content of orthologs, enzymes and metabolic pathways. Non-marine Rhodobacteraceae gained high-affinity transporters to cope with much lower sulphate concentrations and lost genes related to the reduced sodium chloride and organohalogen concentrations in their habitats. Marine Rhodobacteraceae gained genes required for fucoidan desulphonation and synthesis of the plant hormone indole 3-acetic acid and the compatible solutes ectoin and carnitin. However, neither plasmid composition, even though typical for the family, nor the degree of oligotrophy shows a systematic difference between marine and non-marine Rhodobacteraceae. We suggest the operational term 'Roseobacter group' for the marine Rhodobacteraceae strains.
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Affiliation(s)
- Meinhard Simon
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Carmen Scheuner
- Leibniz Institute DSMZ – German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Jan P Meier-Kolthoff
- Leibniz Institute DSMZ – German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Thorsten Brinkhoff
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Irene Wagner-Döbler
- Helmholtz Centre for Infection Research, Research Group Microbial Communication, Braunschweig, Germany
| | - Marcus Ulbrich
- Institute of Biochemical Engineering, Technical University Braunschweig, Braunschweig, Germany
| | - Hans-Peter Klenk
- School of Biology, Newcastle University, Newcastle upon Tyne, UK
| | - Dietmar Schomburg
- Institute of Biochemical Engineering, Technical University Braunschweig, Braunschweig, Germany
| | - Jörn Petersen
- Leibniz Institute DSMZ – German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Markus Göker
- Leibniz Institute DSMZ – German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
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32
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Sun Y, Powell KE, Sung W, Lynch M, Moran MA, Luo H. Spontaneous mutations of a model heterotrophic marine bacterium. ISME JOURNAL 2017; 11:1713-1718. [PMID: 28323279 DOI: 10.1038/ismej.2017.20] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/06/2016] [Accepted: 12/23/2016] [Indexed: 11/09/2022]
Abstract
Heterotrophic marine bacterioplankton populations display substantive genomic diversity that is commonly explained to be the result of selective forces imposed by resource limitation or interactions with phage and predators. Here we use a mutation-accumulation experiment followed by whole-genome sequencing of mutation lines to determine an unbiased rate and molecular spectrum of spontaneous mutations for a model heterotrophic marine bacterium in the globally important Roseobacter clade, Ruegeria pomeroyi DSS-3. We find evidence for mutational bias towards deletions over insertions, and this process alone could account for a sizable portion of genome size diversity among roseobacters and also implies that lateral gene transfer and/or selection must also play a role in maintaining roseobacters with large genome sizes. We also find evidence for a mutational bias in favor of changes from A/T to G/C nucleobases, which explains widespread occurrences of G/C-enriched Roseobacter genomes. Using the calculated mutation rate of 1.39 × 10-10 per base per generation, we implement a 'mutation-rate clock' approach to date the evolution of roseobacters by assuming a constant mutation rate along their evolutionary history. This approach gives an estimated date of Roseobacter genome expansion in good agreement with an earlier fossil-based estimate of ~250 million years ago and is consistent with a hypothesis of a correlated evolutionary history between roseobacters and marine eukaryotic phytoplankton groups.
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Affiliation(s)
- Ying Sun
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
| | - Kate E Powell
- Department of Marine Sciences, University of Georgia, Athens, GA, USA
| | - Way Sung
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Mary Ann Moran
- Department of Marine Sciences, University of Georgia, Athens, GA, USA
| | - Haiwei Luo
- Simon F. S. Li Marine Science Laboratory, School of Life Sciences and Partner State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
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Thompson LR, Williams GJ, Haroon MF, Shibl A, Larsen P, Shorenstein J, Knight R, Stingl U. Metagenomic covariation along densely sampled environmental gradients in the Red Sea. THE ISME JOURNAL 2017; 11:138-151. [PMID: 27420030 PMCID: PMC5315489 DOI: 10.1038/ismej.2016.99] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/08/2016] [Accepted: 06/12/2016] [Indexed: 12/13/2022]
Abstract
Oceanic microbial diversity covaries with physicochemical parameters. Temperature, for example, explains approximately half of global variation in surface taxonomic abundance. It is unknown, however, whether covariation patterns hold over narrower parameter gradients and spatial scales, and extending to mesopelagic depths. We collected and sequenced 45 epipelagic and mesopelagic microbial metagenomes on a meridional transect through the eastern Red Sea. We asked which environmental parameters explain the most variation in relative abundances of taxonomic groups, gene ortholog groups, and pathways-at a spatial scale of <2000 km, along narrow but well-defined latitudinal and depth-dependent gradients. We also asked how microbes are adapted to gradients and extremes in irradiance, temperature, salinity, and nutrients, examining the responses of individual gene ortholog groups to these parameters. Functional and taxonomic metrics were equally well explained (75-79%) by environmental parameters. However, only functional and not taxonomic covariation patterns were conserved when comparing with an intruding water mass with different physicochemical properties. Temperature explained the most variation in each metric, followed by nitrate, chlorophyll, phosphate, and salinity. That nitrate explained more variation than phosphate suggested nitrogen limitation, consistent with low surface N:P ratios. Covariation of gene ortholog groups with environmental parameters revealed patterns of functional adaptation to the challenging Red Sea environment: high irradiance, temperature, salinity, and low nutrients. Nutrient-acquisition gene ortholog groups were anti-correlated with concentrations of their respective nutrient species, recapturing trends previously observed across much larger distances and environmental gradients. This dataset of metagenomic covariation along densely sampled environmental gradients includes online data exploration supplements, serving as a community resource for marine microbial ecology.
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Affiliation(s)
- Luke R Thompson
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Department of Pediatrics, University of California, San Diego, CA, USA
| | - Gareth J Williams
- Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, La Jolla, CA, USA
- School of Ocean Sciences, Bangor University, Anglesey, UK
| | - Mohamed F Haroon
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Ahmed Shibl
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | | | | | - Rob Knight
- Department of Pediatrics, University of California, San Diego, CA, USA
- Department of Computer Science, University of California, San Diego, CA, USA
| | - Ulrich Stingl
- Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
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Francois CM, Duret L, Simon L, Mermillod-Blondin F, Malard F, Konecny-Dupré L, Planel R, Penel S, Douady CJ, Lefébure T. No Evidence That Nitrogen Limitation Influences the Elemental Composition of Isopod Transcriptomes and Proteomes. Mol Biol Evol 2016; 33:2605-20. [PMID: 27401232 DOI: 10.1093/molbev/msw131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The field of stoichiogenomics aims at understanding the influence of nutrient limitations on the elemental composition of the genome, transcriptome, and proteome. The 20 amino acids and the 4 nt differ in the number of nutrients they contain, such as nitrogen (N). Thus, N limitation shall theoretically select for changes in the composition of proteins or RNAs through preferential use of N-poor amino acids or nucleotides, which will decrease the N-budget of an organism. While these N-saving mechanisms have been evidenced in microorganisms, they remain controversial in multicellular eukaryotes. In this study, we used 13 surface and subterranean isopod species pairs that face strongly contrasted N limitations, either in terms of quantity or quality. We combined in situ nutrient quantification and transcriptome sequencing to test if N limitation selected for N-savings through changes in the expression and composition of the transcriptome and proteome. No evidence of N-savings was found in the total N-budget of transcriptomes or proteomes or in the average protein N-cost. Nevertheless, subterranean species evolving in N-depleted habitats displayed lower N-usage at their third codon positions. To test if this convergent compositional change was driven by natural selection, we developed a method to detect the strand-asymmetric signature that stoichiogenomic selection should leave in the substitution pattern. No such signature was evidenced, indicating that the observed stoichiogenomic-like patterns were attributable to nonadaptive processes. The absence of stoichiogenomic signal despite strong N limitation within a powerful phylogenetic framework casts doubt on the existence of stoichiogenomic mechanisms in metazoans.
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Affiliation(s)
- Clémentine M Francois
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
| | - Laurent Duret
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, France
| | - Laurent Simon
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
| | - Florian Mermillod-Blondin
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
| | - Florian Malard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
| | - Lara Konecny-Dupré
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
| | - Rémi Planel
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, France
| | - Simon Penel
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, France
| | - Christophe J Douady
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France Institut Universitaire de France, Paris, France
| | - Tristan Lefébure
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés UMR5023, Villeurbanne, France
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Macqueen DJ, Gubry-Rangin C. Molecular adaptation of ammonia monooxygenase during independent pH specialization in Thaumarchaeota. Mol Ecol 2016; 25:1986-99. [DOI: 10.1111/mec.13607] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/24/2016] [Accepted: 03/02/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel J. Macqueen
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen AB24 2TZ UK
| | - Cécile Gubry-Rangin
- Institute of Biological and Environmental Sciences; University of Aberdeen; Aberdeen AB24 2TZ UK
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