Fluorescent<em> In situ</em> Hybridisering (FISH) til at identificere mRNA transkripter i individuelle celler muliggør analyse af polygen aktivitet såsom den samtidige transskription af mere end ét medlem af<em> Var</em> Multigenfamilie i<em> Plasmodium falciparum</em> Inficerede erythrocytter<sup> 1</sup>. Teknikken er fleksibel og kan anvendes på forskellige typer af gener, celler og organismer.
Adhæsion af Plasmodium falciparum inficerede erythrocytter (IE) til humane endotel receptorer under malariainfektioner medieres ved ekspression af PfEMP1 proteinvarianter kodet af VaR gener.
The haploid P. falciparum genom havne cirka 60 forskellige was gener, hvoraf kun én er blevet menes at blive transskriberet per celle ad gangen i blodet fase af infektionen. Hvordan en sådan gensidigt udelukker regulering af var gentranskription opnås er uklar, da er at identificere individuelle was gener eller undergrupper af VaR gener forbundet med forskellige receptorer og konsekvensen af forskellen binding på det kliniske resultat af P. falciparum infektioner. Senest har gensidigt udelukker transkription paradigme været draget i tvivl ved transskription assays baseret på individuel P. falciparum udskrift identifikation i en enkelt infected erytrocytiske celler under anvendelse af RNA fluorescerende in situ hybridisering (FISH) analyse af var gentranskription af parasitten i enkelte kerner af P. falciparum IE 1.
Her præsenterer vi en detaljeret protokol til udførelse af RNA-FISH metode til analyse af var gentranskription i single-kerner af P. falciparum inficerede humane erythrocytter. Fremgangsmåden er baseret på anvendelse af digoxigenin-og biotin-mærket antisense RNA-prober ved hjælp af TSA Plus Fluorescence Palette System 2 (Perkin Elmer), mikroskopiske analyser og frisk valgt P. falciparum IE. Den in situ-hybridisering metode kan bruges til at overvåge transkription og regulering af en række gener udtrykt under de forskellige faser af P. falciparum livscyklus og kan tilpasses til andre malariaparasitten arter og andre organismer og celletyper.
RNA FISH-analyse, i modsætning til fremgangsmåder såsom Northern blotting og RT-PCR, muliggør diskriminering af specifikke mRNA-transkripter på enkeltcelleniveau. Dette gør det muligt at skelne mellem transkriptionelt aktive og inaktive celler, i dette eksempel, P. falciparum parasitiske protozoer inden i humane røde blodlegemer. Sådanne helcelle-observationer er ofte nødvendige, og kan udrede vigtige og hidtil ukendte transkriptionelle mønstre en.
Selvom andre …
The authors have nothing to disclose.
Forfatterne vil gerne takke Michael Alifrangis og Ulla Abildtrup til genotypning af parasitter og Christina Holm for fremragende teknisk bistand. Dette arbejde blev finansieret af Howard Hughes Medical Institute (tilskud 55.005.511), Lundbeckfonden (tilskud R9-A840) og af Niels Bohr Instituttet.
Name of the reagent | Company | Catalogue number | Comments |
Acetic Acid | Sigma/Aldrich | 338826-100ml | |
Albumax media: RPMI 1640 Glutamine solution | Lonza | BE12-115F | 500 ml RPMI 1640
5 ml glutamine solution |
Albumax media: Gentamycin sulphate Albumax-solution | Lonza | BE02-012E | 2.5 ml gentamycin sulphate
50 ml Albumax-solution |
Albumax-solution: Hypoxanthine | Sigma-Aldrich | H9377 | 0.8 g Hypoxanthine |
Albumax-solution: AlbuMAX II | Invitrogen | 11021-037 | 200 g Albumax |
Albumax-solution: RPMI 1640 | Lonza | BE12-115F | 4 liter RPMI 1640
Dissolve with magnet at max. 50 °C. Filter sterilize and store at -20 °C in aliquots. |
Amberlite | Sigma | A5710-110G | Resin to deionize formamide. |
Anti-biotin goat pAb Peroxidase Conjugate | Calbiochem | 203206 | |
Anti-Dig antibody | Novus biologicals | NB100-41330 | |
Anti-fade reagent with DAPI | Invitrogen | P36931 | The mounting media has to cure for 24 hr before sealing the slide completely. |
Biotin RNA Labeling Mix | Roche | 11685597910 | |
Camera digital | Nikon digital sight DC-F11 | ||
Coverslips | Menzel-glaser | 631-1570 | |
culture flask 25 cm2 Nunclon surface | Nunc | 156340 | |
DEPC | Fluka/Sigma | 32490-100ml | 1 ml DEPC in 1000 ml deinonized water. Add a stir bar and stir for 12 hr. Autoclave for 30 min. |
Digital camera | Nikon digital sight DC-F11 | ||
Dynabeads Protein A | Invitrogen | 10002D | |
DynaMaq-15 Magnet | Invitrogen | 123-01D | |
Formamide bioultra 99 % | Fluka/Sigma | 47671-1l-F | Deionized formamide: 5 g of ion exchange resin per 100 ml of formamide. Stir 30 min. Filter through Whatman paper. |
Gelatine 0.75% solution: Gelatine | Sigma-Aldrich | G2500 | 3.75 g gelatine in 500 ml RPMI 1640. Heat to 56 °C to dissolve. Filter sterilize when 56 °C. Store at -20 °C in aliquots. |
Gelatine 0.75% solution: RPMI 1640 | Lonza | BE12-115F | 3.75 g gelatine in 500 ml RPMI 1640. Heat to 56 °C to dissolve. Filter sterilize when 56 °C. Store at -20 °C in aliquots. |
Glutamine solution: L-glutamin | Sigma-Aldrich | G3126 | 14.6 g L glutamine in 500 ml 0.9 % NaCl. Dissolve, filter sterilize and store at -20 °C in aliquots. |
Glutamine solution: HCl | Sigma | H1758 | 14.6 g L glutamine in 500 ml 0.9 % NaCl. Dissolve, filter sterilize and store at -20 °C in aliquots. |
Hybridization solution: Formamide Bio ultra 99% SSC 20x | Fluka/Sigma | 47671-1l-F | Total 20 ml, keep frozen at -20 °C in aliquots 10 ml deionized formamide |
Hybridization solution: Denhardt’s 50x concentrate | Sigma | D2532 | 5 ml 20xSSC |
Hybridization solution: Yeast tRNARoche blocking reagent | Sigma | R-6750 | 2 ml 50x Denhardt’s 250 μl 20 mg per ml yeast tRNA |
Hybridization solution: Salmon sperm DNA | Fluka/Sigma | 31149-106GF | 0.4 g Roche blocking reagent 1 ml of 10 mg per ml salmon sperm DNA (Critical: denature salmon spermDNA at 96 °C for 5 min before adding to the hybridization solution) |
Hybridizer ThermoStar 100 HC4 | Quantifoil Instruments GmbH | 1004-0011 | Can be replaced by hybridization oven and RNase free hybridization chambers padded with DEPC water. |
Immersion oil UV transparent fluorescence free | Sigma | 10976-1EA | |
Immunofluorescence or confocal microscope | Nikon D-Eclipse TE2000C | ||
Nailpolish | Available in any drugstore | ||
PBS 20x:NaCl
KCl Na2HPO4 x 2H2O KH2PO4 DEPC deionized H2O |
Ajust pH to 7.4
160 g 4 g 23 g 4 g 1 l |
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Paraformaldehyde 4 % | Fluka/chemika | 76240 | 4 g PFA in 80 ml PBS/DEPC. Heat to 65 °C until the PFA dissolves. Add 20 ml PBS, allow the solution to cool. Adjust the pH to 7.4. Filter. Store in aliquots at -20 °C. |
Paraformaldehyde 4 %/ Acid acetic 5 % | 950 μl paraformaldhyde + 50 μl Acetic acid | ||
Pepsin | Sigma/Aldrich | P7000 | |
Peroxidase-conjugated anti-biotin | Calbiochem | 203206 | |
RBC-wash media: RPMI 1640 Glutamine solution | Lonza | BE12-115F | 500 ml RPMI 1640 5 ml glutamine solution |
RBC-wash media: Gentamycin sulfate | Lonza | BE02-012E | 2.5 ml gentamycin sulphate |
RNase | Sigma/Aldrich | Make a 10 mg/ml stock solution. | |
RNase free 1.5 ml tube | Ambion | AM12450 | |
RNase Zap | Ambion | AM9780 | |
Slides 4 wells 11 mm | Thermo Scientific | MENZXER306W | |
SSC 20x: NaCl | Sigma/Aldrich | S9625 | 3 M NaCl (175 g/l) 0.3M Na3 citrate x H2O (88 g/l) Adjust to pH 7.0 with 1M HCl |
SSC 20x: Sodium citrate dehydrate | Sigma/aldrich | W302600 | 3 M NaCl (175 g/l) 0.3M Na3 citrate x H2O (88 g/l) Adjust to pH 7.0 with 1M HCl |
SSPE 20x: NaCl | Sigma/Aldrich | S9625 | 175.3 g NaCl |
SSPE 20x: NaH2PO4 | Sigma/Aldrich | S0751 | 27.6 g NaH2PO4. |
SSPE 20x:4 EDTA powder | 9.4 g EDTA powder Add DEPC water, adjust pH 7.4. Autoclave for 20 min |
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TNB buffer: TNT buffer | 10 ml TNT buffer | ||
TNB buffer: Blocking reagent | 0.05 g Blocking reagent To dissolve the blocking reagent, heat the solution to 60 °C for one hour with stirring. Store at -20 °C. (Derived from the Perkin Elmer TSA-protocol.) |
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TNT buffer: Tris/HCl | Sigma | T1503 | 1M Tris/HCl, pH 8.0 |
TNT buffer: NaCl | Sigma Aldrich | S9625 | 100 ml |
TNT buffer: Tween20 | Sigma | 93773 | 5 M NaCl 30 ml 1 ml DEPC dH2O 869 Ml Adjust pH to 7.5 at room temperature. (Derived from the Perkin Elmer TSA-protocol.) |
TSA plus Cyanine3/ Fluorescein system | Perkin Elmer | NEL753000IKT | Read the protocol from the TSA Plus Fluorescence Palette System carefully before starting the experiment. |
Tubes 14 ml sterile | Almeco – CM LAB Aps | 91016 |