title: Fluorescence in situ hybridization of Microcystis strains producing microcystin using specific mRNA probes.
abstract: Cyanobacteria are ubiquitous micro-organisms that can produce toxic compounds, the cyanotoxins. The monitoring of such producers in the environment is of prime importance for human health. An attractive technology for such monitoring is fluorescence in situ hybridization (FISH), which allows the detection and enumeration of environmental micro-organisms. We present here the application of tyramide signal amplification fluorescence in situ hybridization (TSA-FISH) to the detection of microcystin-producing Microcystis strains. We used a 16S rRNA-specific probe, MICR3, to specifically label and observe by epifluorescence microscopy Microcystis aeruginosa strains. Using confocal laser scanning microscopy and a specific probe, MCYA, targeting the mcyA mRNA we have labelled M. aeruginosa PCC 7806, which produces microcystins. Microcystis aeruginosa PCC 7005 which does not produce microcystins is not labelled by this probe. Furthermore, we show here that this specific mRNA labelling in M. aeruginosa PCC 7806 is enhanced in cells illuminated for 1 h just after a dark period of cultivation of 24 h, conditions in which the mcyA gene is up regulated. The data presented here might be applicable to the monitoring of toxic Microcystis strains in the environment.
  
  
  CONCLUSIONS
  Cyanobacteria producing toxic compounds (cyanotoxins) are present in the environment and in water bodies. Their presence poses a threat on human and animal health. It is thus important to detect, identify and enumerate these toxic Cyanobacteria. Using tyramide signal amplification fluorescence in situ hybridization (TSA-FISH) and specific probes, with confocal laser scanning microscopy, we have specifically detected Microcystis strains producing microcystin toxins. The data presented here might be applied to the monitoring of water bodies at early stages and all along the formation of Microcystis blooms.
authors.affiliation: Chimie ParisTech, Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Zeller
authors.affiliation: Laboratoire des Energies de Demain, LIED, UMR 8236 CNRS, Université Paris Diderot-Paris 7, Paris, France. annick.mejean@univ-paris-diderot.fr.
authors.forename: A
authors.initials: A
authors.lastname: Méjean
authors.affiliation: CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM110, Aix-Marseille Université, Marseille, France.
authors.forename: I
authors.initials: I
authors.lastname: Biegala
authors.affiliation: Institut Jacques Monod, CNRS UMR 7592, Sorbonne Paris Cité, Université Paris Diderot, Paris Cedex, France.|ImagoSeine, Institut Jacques Monod, CNRS UMR 7592, Sorbonne Paris Cité, Université Paris Diderot, Paris Cedex, France.
authors.forename: V
authors.initials: V
authors.lastname: Contremoulins
authors.affiliation: Chimie ParisTech, Paris, France. olivier.ploux@chimie-paristech.fr.|Laboratoire des Energies de Demain, LIED, UMR 8236 CNRS, Université Paris Diderot-Paris 7, Paris, France. olivier.ploux@chimie-paristech.fr.
authors.forename: O
authors.initials: O
authors.lastname: Ploux
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics*; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D052998:Microcystins / Q000235:genetics*; D046931:Microcystis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D018613:Microscopy, Confocal; D012333:RNA, Messenger / Q000032:analysis*; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D052998:Microcystins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C078588:microcystin
keywords: 
  Microcystis
  ; 
  mcyA
  ; Cyanobacteria; microcystin; tyramide signal amplification fluorescence in situ hybridization