title: Single-cell transcriptome analysis of fish immune cells provides insight into the evolution of vertebrate immune cell types.
abstract: The immune system of vertebrate species consists of many different cell types that have distinct functional roles and are subject to different evolutionary pressures. Here, we first analyzed conservation of genes specific for all major immune cell types in human and mouse. Our results revealed higher gene turnover and faster evolution oftrans-membrane proteins in NK cells compared with other immune cell types, and especially T cells, but similar conservation of nuclear and cytoplasmic protein coding genes. To validate these findings in a distant vertebrate species, we used single-cell RNA sequencing oflck:GFPcells in zebrafish and obtained the first transcriptome of specific immune cell types in a nonmammalian species. Unsupervised clustering and single-cellTCRlocus reconstruction identified three cell populations, T cells, a novel type of NK-like cells, and a smaller population of myeloid-like cells. Differential expression analysis uncovered new immune-cell-specific genes, including novel immunoglobulin-like receptors, and neofunctionalization of recently duplicated paralogs. Evolutionary analyses confirmed the higher gene turnover oftrans-membrane proteins in NK cells compared with T cells in fish species, suggesting that this is a general property of immune cell types across all vertebrates.
authors.affiliation: Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland.|Swiss Institute of Bioinformatics (SIB), 1015 Lausanne, Switzerland.
authors.forename: Santiago J
authors.identifier: 0000-0002-2495-0671
authors.initials: SJ
authors.lastname: Carmona
authors.affiliation: European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom.|Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SA, United Kingdom.
authors.forename: Sarah A
authors.identifier: 0000-0002-6294-6366
authors.initials: SA
authors.lastname: Teichmann
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SA, United Kingdom.|Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom.|Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge CB2 1QR, United Kingdom.
authors.forename: Lauren
authors.initials: L
authors.lastname: Ferreira
authors.affiliation: Sanger Institute-EBI Single-Cell Genomics Centre, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1HH, United Kingdom.
authors.forename: Iain C
authors.initials: IC
authors.lastname: Macaulay
authors.affiliation: European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom.
authors.forename: Michael J T
authors.initials: MJ
authors.lastname: Stubbington
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SA, United Kingdom.|Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom.|Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge CB2 1QR, United Kingdom.
authors.forename: Ana
authors.identifier: 0000-0003-3204-9311
authors.initials: A
authors.lastname: Cvejic
authors.affiliation: Ludwig Center for Cancer Research, University of Lausanne, 1066 Epalinges, Switzerland.|Swiss Institute of Bioinformatics (SIB), 1015 Lausanne, Switzerland.
authors.forename: David
authors.identifier: 0000-0002-3952-0930
authors.initials: D
authors.lastname: Gfeller
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D051379:Mice; D017452:Receptors, IgG / Q000235:genetics*; D059010:Single-Cell Analysis; D059467:Transcriptome; D015027:Zebrafish / Q000235:genetics / Q000276:immunology; D029961:Zebrafish Proteins / Q000235:genetics*
chemical_list: D017452:Receptors, IgG; D029961:Zebrafish Proteins