title: Picomonas judraskeda gen. et sp. nov.: the first identified member of the Picozoa phylum nov., a widespread group of picoeukaryotes, formerly known as 'picobiliphytes'.
abstract: In 2007, a novel, putatively photosynthetic picoeukaryotic lineage, the 'picobiliphytes', with no known close eukaryotic relatives, was reported from 18S environmental clone library sequences and fluorescence in situ hybridization. Although single cell genomics later showed these organisms to be heterotrophic rather than photosynthetic, until now this apparently widespread group of pico-(or nano-)eukaryotes has remained uncultured and the organisms could not be formally recognized. Here, we describe Picomonas judraskeda gen. et sp. nov., from marine coastal surface waters, which has a 'picobiliphyte' 18S rDNA signature. Using vital mitochondrial staining and cell sorting by flow cytometry, a single cell-derived culture was established. The cells are biflagellate, 2.5-3.8×2-2.5 µm in size, lack plastids and display a novel stereotypic cycle of cell motility (described as the "jump, drag, and skedaddle"-cycle). They consist of two hemispherical parts separated by a deep cleft, an anterior part that contains all major cell organelles including the flagellar apparatus, and a posterior part housing vacuoles/vesicles and the feeding apparatus, both parts separated by a large vacuolar cisterna. From serial section analyses of cells, fixed at putative stages of the feeding cycle, it is concluded that cells are not bacterivorous, but feed on small marine colloids of less than 150 nm diameter by fluid-phase, bulk flow endocytosis. Based on the novel features of cell motility, ultrastructure and feeding, and their isolated phylogenetic position, we establish a new phylum, Picozoa, for Picomonas judraskeda, representing an apparently widespread and ecologically important group of heterotrophic picoeukaryotes, formerly known as 'picobiliphytes'.
authors.affiliation: Department of Botany, Cologne Biocenter, University of Cologne, Cologne, Germany. rseeniva@uni-koeln.de
authors.forename: Ramkumar
authors.initials: R
authors.lastname: Seenivasan
authors.forename: Nicole
authors.initials: N
authors.lastname: Sausen
authors.forename: Linda K
authors.initials: LK
authors.lastname: Medlin
authors.forename: Michael
authors.initials: M
authors.lastname: Melkonian
mesh_terms: D002465:Cell Movement; D056890:Eukaryota / Q000166:cytology / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D005434:Flow Cytometry; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics
chemical_list: D012337:RNA, Ribosomal, 18S
references.citation: Proc Biol Sci. 2006 Jul 22;273(1595):1833-42
references.pmid: 16790418
references.citation: Environ Microbiol. 2008 Jun;10(6):1621-34
references.pmid: 18341584
references.citation: Protist. 2005 Aug;156(2):163-79
references.pmid: 16171184
references.citation: Science. 2011 May 6;332(6030):714-7
references.pmid: 21551060
references.citation: Appl Environ Microbiol. 2009 Oct;75(19):6373-81
references.pmid: 19666727
references.citation: Science. 2008 Nov 21;322(5905):1254-7
references.pmid: 19023082
references.citation: ISME J. 2011 Feb;5(2):184-95
references.pmid: 20631807
references.citation: Protist. 2012 Jul;163(4):632-42
references.pmid: 22186014
references.citation: Sci China C Life Sci. 2008 Dec;51(12):1121-8
references.pmid: 19093087
references.citation: Appl Environ Microbiol. 2004 Jul;70(7):4064-72
references.pmid: 15240284
references.citation: Proc Biol Sci. 2012 Jun 7;279(1736):2246-54
references.pmid: 22298847
references.citation: Microbiol Mol Biol Rev. 1999 Mar;63(1):106-27
references.pmid: 10066832
references.citation: Annu Rev Microbiol. 2011;65:91-110
references.pmid: 21639789
references.citation: Nature. 2005 Sep 15;437(7057):356-61
references.pmid: 16163346
references.citation: Environ Microbiol. 2006 Sep;8(9):1515-22
references.pmid: 16913912
references.citation: J Eukaryot Microbiol. 2012 Sep;59(5):429-93
references.pmid: 23020233
references.citation: FEMS Microbiol Rev. 2008 Aug;32(5):795-820
references.pmid: 18564290
references.citation: Nature. 2005 Sep 15;437(7057):343-8
references.pmid: 16163344
references.citation: FEMS Microbiol Ecol. 2004 Nov 1;50(3):231-43
references.pmid: 19712363
references.citation: J Eukaryot Microbiol. 2010 Mar-Apr;57(2):159-70
references.pmid: 20015186
references.citation: Curr Opin Biotechnol. 2012 Jun;23(3):437-43
references.pmid: 22154471
references.citation: Curr Opin Microbiol. 2008 Jun;11(3):213-8
references.pmid: 18556239
references.citation: Microb Ecol. 2011 Aug;62(2):383-98
references.pmid: 21373815
references.citation: Res Microbiol. 2008 Jan-Feb;159(1):67-73
references.pmid: 18207371
references.citation: Science. 2007 Jan 12;315(5809):253-5
references.pmid: 17218530
references.citation: Nucleic Acids Res. 2003 Jul 1;31(13):3406-15
references.pmid: 12824337
references.citation: Antonie Van Leeuwenhoek. 2002 Aug;81(1-4):293-308
references.pmid: 12448728
references.citation: Bioinformatics. 2004 Feb 12;20(3):407-15
references.pmid: 14960467
references.citation: Nature. 2001 Feb 1;409(6820):603-7
references.pmid: 11214316
references.citation: Bioinformatics. 1998;14(9):817-8
references.pmid: 9918953
references.citation: Nature. 2001 Feb 1;409(6820):607-10
references.pmid: 11214317
references.citation: Arch Virol. 2012 Oct;157(10):1851-71
references.pmid: 22760663
references.citation: PLoS One. 2012;7(7):e41970
references.pmid: 22860041
references.citation: Environ Microbiol. 2007 May;9(5):1233-52
references.pmid: 17472637
references.citation: Bioinformatics. 2003 Aug 12;19(12):1572-4
references.pmid: 12912839
references.citation: Nucleic Acids Res. 2004 Jan 1;32(Database issue):D101-3
references.pmid: 14681368
references.citation: Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14679-84
references.pmid: 20668244
references.citation: Appl Environ Microbiol. 2001 Jul;67(7):2932-41
references.pmid: 11425705
references.citation: Curr Biol. 2012 Sep 11;22(17):R675-7
references.pmid: 22974991
references.citation: Curr Opin Microbiol. 2012 Oct;15(5):613-20
references.pmid: 23026140
references.citation: ISME J. 2011 Apr;5(4):674-84
references.pmid: 20962875
references.citation: Appl Environ Microbiol. 1999 Jan;65(1):45-52
references.pmid: 9872758
references.citation: Bioinformatics. 2006 Nov 1;22(21):2688-90
references.pmid: 16928733
references.citation: J Struct Biol. 1996 Jan-Feb;116(1):71-6
references.pmid: 8742726
references.citation: Science. 2012 Feb 10;335(6069):671-6
references.pmid: 22323811
references.citation: Appl Environ Microbiol. 2003 Sep;69(9):5519-29
references.pmid: 12957941
references.citation: Science. 2008 May 23;320(5879):1043-5
references.pmid: 18497289
references.citation: Protist. 2010 Oct;161(4):523-38
references.pmid: 20418156
references.citation: PLoS One. 2009 Sep 17;4(9):e7080
references.pmid: 19759916
references.citation: Proc Natl Acad Sci U S A. 2011 Jan 25;108(4):1496-500
references.pmid: 21205890
references.citation: Microbiol Mol Biol Rev. 2009 Jun;73(2):249-99
references.pmid: 19487728
references.citation: J Cell Sci. 2004 Jun 1;117(Pt 13):2663-74
references.pmid: 15138287
references.citation: Microb Ecol. 2006 Jul;52(1):53-71
references.pmid: 16703447