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QIA39 FragEL™ DNA Fragmentation Detection Kit, Fluorescent - TdT Enzyme

MSDS (material safety data sheet) or SDS, CoA and CoQ, dossiers, brochures and other available documents.

Synonyms: TUNEL Assay

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QIA39
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Overview

Replacement Information

Key Spec Table

Detection Methods
Fluorescence

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      Description
      OverviewAllows for detection of apoptosis at the individual cell level. Apoptosis morphology is easily detected. Detection is by flow cytometry or fluorescence microscopy. The kit mounting media permits the observance of the total cell population.
      Cat. No. QIA39 is a fluorescein-conjugated version of our widely referenced TdT Colorimetric FragEL™ DNA Fragmentation Detection Kit (Cat. No. QIA33) for non-isotopic labeling. Terminal deoxynucleotidyl transferase (TdT) binds to exposed 3′-OH ends of DNA fragments generated in response to apoptotic signals and catalyzes the addition of fluorescein-labeled and unlabeled deoxynucleotides. When excited, fluorescein generates an intense signal which can be detected by fluorescence microscopy or flow cytometry. The mounting media sustains the fluorescent signal from samples labeled on slides and, therefore, aids in the morphological evaluation and characterization of normal and apoptotic cells. Non-apoptotic cells can be visualized by a DAPI filter.
      Catalogue NumberQIA39
      Brand Family Calbiochem®
      SynonymsTUNEL Assay
      Materials Required but Not Delivered• xylene
      • ethanol, 70, 80, 90, 100%
      • 4% formaldehyde in PBS
      • 10 mM Tris pH 8
      • TBS (20 mM Tris pH 7.6, 140 mM NaCl)
      • 1 mM MgSO4 in TBS (optional, for use in generating positive control)
      • DNaseI (optional, for use in generating positive control)
      • distilled water
      • coplin jars, glass or plastic with slide holders
      • wash bottle or beaker for rinsing slides
      • humidified chamber
      • glass coverslips
      • fluorescence microscope or flow cytometer
      • 2-20 µl, 20-200 µl, and 200-1000 µl precision pipettors with disposable tips
      • microcentrifuge tubes
      • parafilm®
      • absorbent wipes
      • ice
      References
      ReferencesDarzynkiewicz, Z., et al. 1997. Cytometry 27, 1.
      Frey, T. 1997. Cytometry 28, 253.
      Shapiro, H.M. 1995. Practical Flow Cytometry, Third Edition. Wiley-Liss Inc., New York, New York.
      Darzynkiewicz, Z., et al. 1992. Cytometry 13, 795.
      Gavrieli, Y., et al. 1992. J. Cell Biol. 119, 493.
      Fawthrop, D. J., et al. 1991. Arch. Toxicol. 65, 437.
      Martin, S.J., et al. 1990. J. Immunology 145, 1859.
      Wyllie, A. H. 1980. Nature 284, 555.
      Kerr, J. F. R., et al. 1972. Br. J. Cancer 26, 239.
      Product Information
      Detection methodFluorescence
      Form50 Tests
      FormatFlow cytometry or fluorescence microscopy
      Kit containsProteinase K, Equilibration and Labeling Buffers, TdT Enzyme (Cat. No. PF060), Control Slides, Mounting Media (Cat. No. HC08), and a user protocol.
      Quality LevelMQ100
      Applications
      Key Applications Flow Cytometry
      Biological Information
      Assay time2 h
      Sample TypeFrozen or paraffin sections, fixed cell preparations or cell suspensions
      Species Reactivity
      • A Broad Range Of Species
      Physicochemical Information
      Dimensions
      Materials Information
      Toxicological Information
      Safety Information according to GHS
      Safety Information
      R PhraseR: 23/25-34-36/37/38-42/43-45-61

      Toxic by inhalation and if swallowed.
      Causes burns.
      Irritating to eyes, respiratory system and skin.
      May cause sensitization by inhalation and skin contact.
      May cause cancer.
      May cause harm to the unborn child.
      S PhraseS: 26-27-36/37/39-45-53

      In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
      Take off immediately all contaminated clothing.
      Wear suitable protective clothing, gloves and eye/face protection.
      In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible).
      Avoid exposure - obtain special instructions before use.
      Product Usage Statements
      Intended useThe Calbiochem® Fluorescein-FragEL™ DNA Fragmentation Detection Kit is a non-isotopic system for the labeling of DNA breaks in apoptotic nuclei in paraffin-embedded tissue sections, tissue cryosections, in cell preparations fixed on slides, or in cell suspensions. Detection and analysis of labeling is possible by flow cytometry or fluorescence microscopy.
      Storage and Shipping Information
      Ship Code Dry Ice Only
      Toxicity Multiple Toxicity Values, refer to MSDS
      Hazardous Materials Attention: Due to the nature of the Hazardous Materials in this shipment, additional shipping charges may be applied to your order. Certain sizes may be exempt from the additional hazardous materials shipping charges. Please contact your local sales office for more information regarding these charges.
      Storage -20°C
      Storage ConditionsFluorescein-FragEL™ kit components are shipped on dry ice. Upon receipt, store kit at -20°C in a non-frost-free freezer. To avoid reagent loss in tube caps, briefly pulse spin all thawed solutions before removing caps. (see General Considerations below).
      Avoid freeze/thaw Avoid freeze/thaw
      Do not freeze Ok to freeze
      Packaging Information
      Transport Information
      Supplemental Information
      Kit containsProteinase K, Equilibration and Labeling Buffers, TdT Enzyme (Cat. No. PF060), Control Slides, Mounting Media (Cat. No. HC08), and a user protocol.
      Specifications
      Global Trade Item Number
      Catalogue Number GTIN
      QIA39-1EA 07790788054045

      Documentation

      FragEL™ DNA Fragmentation Detection Kit, Fluorescent - TdT Enzyme SDS

      Title

      Safety Data Sheet (SDS) 

      FragEL™ DNA Fragmentation Detection Kit, Fluorescent - TdT Enzyme Certificates of Analysis

      TitleLot Number
      QIA39

      References

      Reference overview
      Darzynkiewicz, Z., et al. 1997. Cytometry 27, 1.
      Frey, T. 1997. Cytometry 28, 253.
      Shapiro, H.M. 1995. Practical Flow Cytometry, Third Edition. Wiley-Liss Inc., New York, New York.
      Darzynkiewicz, Z., et al. 1992. Cytometry 13, 795.
      Gavrieli, Y., et al. 1992. J. Cell Biol. 119, 493.
      Fawthrop, D. J., et al. 1991. Arch. Toxicol. 65, 437.
      Martin, S.J., et al. 1990. J. Immunology 145, 1859.
      Wyllie, A. H. 1980. Nature 284, 555.
      Kerr, J. F. R., et al. 1972. Br. J. Cancer 26, 239.

      Brochure

      Title
      Caspases and other Apoptosis Related Tools Brochure
      Kit SourceBook - 2nd Edition EURO
      Kits SourceBook - 2nd Edition GBP

      Citations

      Title
    • Lili A. Barouch, et al. (2006) Cardiac Myocyte Apoptosis Is Associated With Increased DNA Damage and Decreased Survival in Murine Models of Obesity. Circulation Research 98, 119-124.
      		•
      User Protocol

      Revision20-May-2016 JSW
      SynonymsTUNEL Assay
      Form50 Tests
      FormatFlow cytometry or fluorescence microscopy
      Detection methodFluorescence
      Speciesa broad range of species
      StorageFluorescein-FragEL™ kit components are shipped on dry ice. Upon receipt, store kit at -20°C in a non-frost-free freezer. To avoid reagent loss in tube caps, briefly pulse spin all thawed solutions before removing caps. (see General Considerations below).
      Intended useThe Calbiochem® Fluorescein-FragEL™ DNA Fragmentation Detection Kit is a non-isotopic system for the labeling of DNA breaks in apoptotic nuclei in paraffin-embedded tissue sections, tissue cryosections, in cell preparations fixed on slides, or in cell suspensions. Detection and analysis of labeling is possible by flow cytometry or fluorescence microscopy.
      BackgroundCell death has been shown to occur by two major mechanisms, necrosis, and apoptosis. Classical necrotic cell death occurs due to noxious injury or trauma while apoptosis takes place during normal cell development, regulating cellular differentiation and number. While necrotic cell death results in cell lysis, cellular apoptosis is characterized morphologically by cell shrinkage, nuclear pyknosis, chromatin condensation, and blebbing of the plasma membrane. A cascade of molecular and biochemical events has been identified including activation of an endogenous endonuclease that cleaves DNA into oligonucleosomes detectable as a ladder of DNA fragments in agarose gels. Observation of oligonucleosomal DNA fragments by DNA laddering has long been the most acceptable and only available assay for the detection of apoptosis. However, this methodology has numerous disadvantages such as a lack of sensitivity and specificity; lengthy preparation time, requiring a high level of expertise; and inability to discern which cells in a population are undergoing apoptosis. Apoptotic endonucleases not only affect cellular DNA by producing the classical DNA ladder but also generate free 3'-OH groups at the ends of these DNA fragment. The Fluorescein-FragEL™ DNA Fragmentation Detection Kit labels these hydroxyl groups with fluorescein-conjugated deoxynucleotides. This direct incorporation of excitable bases simplifies the FragEL™ procedure by eliminating the need for secondary detection steps resulting in rapid, sensitive, and specific staining of DNA fragments. Fluorescein is the predominant green fluorochrome used in fluorescence microscopy and flow cytometry applications. Photostability is achieved through the utilization of the Fluorescein-FragEL™ mounting media designed to enhance and preserve fluorescein emission. DNA modification is not the only indicator of apoptotic cell death. One can histologically recognize apoptotic cells in a population by identifying the well-characterized morphological changes. The Fluorescein-FragEL™ DNA Fragmentation Detection Kit allows one to simultaneously evaluate both of these apoptotic indices when labeling samples on a slide. DNA strand breakage is identified within morphologically intact cell specimens allowing for a more concise differentiation between the normal and apoptotic cell. The versatility of this non-isotopic kit permits the identification of cellular apoptosis in fresh cultured cells, paraffin-embedded tissues, tissue cryosections, or cell suspensions.
      Principles of the assayWhen excited, fluorescein generates an intense signal that can be detected by fluorescence microscopy or flow cytometry. In this assay terminal deoxynucleotidyl transferase (TdT) binds to exposed 3'-OH ends of DNA fragments generated in response to apoptotic signals and catalyzes the addition of fluorescein-labeled and unlabeled deoxynucleotides. The Mounting Media sustains the fluorescent signal from samples labeled on slides and therefore aids in the morphological evaluation and characterization of normal and apoptotic cells. Inclusion of 4,6,-DiAmidino-2-PhenylIndole (DAPI) in the Mounting Media allows for the visualization of both unlabeled and labeled cells at an excitation wavelength of 330-380 nm.

      The Calbiochem® Fluorescein DNA Fragmentation Detection Kit allows the recognition of apoptotic nuclei in paraffin-embedded tissue sections, tissue cryosections, in cell preparations fixed on slides, or in cell suspensions by Fragment End Labeling (FragEL™) of DNA.

      Figure 1: Principle of the Assay
      Materials providedThe Fluorescein-FragEL™ kit supplies sufficient reagents to stain 50 specimens.
      • PROTEINASE K (Kit Component No. JA1477): 2 mg/ml Proteinase K in 10 mM Tris, pH 8
      • 5X TdT EQUILIBRATION BUFFER (Kit Component No. JA1748):
      • FLUORESCEIN-FragEL™ LABELING REACTION MIX (Kit Component No. JA1834): 3 vials containing a mixture of labeled and unlabeled deoxynucleotides at a ratio optimized for DNA Fragment End Labeling with TdT
      • TdT ENZYME (Kit Component No. JA1560): Terminal Deoxynucleotidyl Transferase
      • Fluorescent Mounting Media (Kit Component No. JA1750): An aqueous mounting media, containing DAPI, designed to preserve and enhance fluorescein fluorescence and to allow for the visualization of the total cell population.
      • CONTROL SLIDES (Kit Component No. JA1609): Two similar slides. A mixture of HL-60 cells incubated with 0.5 µg/ml actinomycin D for 19 h to induce apoptosis and HL-60 uninduced cells. Supplied as formaldehyde-fixed cytospin® preparations.
      Materials Required but not provided• xylene
      • ethanol, 70, 80, 90, 100%
      • 4% formaldehyde in PBS
      • 10 mM Tris pH 8
      • TBS (20 mM Tris pH 7.6, 140 mM NaCl)
      • 1 mM MgSO4 in TBS (optional, for use in generating positive control)
      • DNaseI (optional, for use in generating positive control)
      • distilled water
      • coplin jars, glass or plastic with slide holders
      • wash bottle or beaker for rinsing slides
      • humidified chamber
      • glass coverslips
      • fluorescence microscope or flow cytometer
      • 2-20 µl, 20-200 µl, and 200-1000 µl precision pipettors with disposable tips
      • microcentrifuge tubes
      • parafilm®
      • absorbent wipes
      • ice
      Precautions and recommendations• For optimal results READ THESE INSTRUCTIONS BEFORE USING THIS KIT.
      • The TdT Enzyme will not solidify at -20°C. To preserve the activity of this enzyme, do not remove it from the freezer until immediately before use in preparing the labeling reaction mixture. At this point either pipet the enzyme directly from the freezer or momentarily place it in a -20°C storage device designed for bench top use.
      • All other FragEL™ kit components, with the exception of the Mounting Media, should be kept on ice during usage then promptly returned to -20°C. The Mounting Media should also be stored at -20°C. Unnecessary thawing and freezing should be avoided.
      • To avoid reagent loss in tube caps, briefly pulse spin all thawed solutions before removing caps.
      • The Mounting Media may be carcinogenic and teratogenic and may also irritate skin and eyes. Cacodylic acid is toxic and carcinogenic. Avoid contact with eyes and skin. Do not ingest.
      • Gloves, lab coat, and protective eyewear should be worn.
      • A separate protocol has been provided for the end labeling of paraffin-embedded tissue sections, tissue cryosections, cell preparations fixed on slides, and cells in suspension. See the section appropriate to your sample. HL-60 control slides should be labeled using the fixed cells protocol.
      • HL-60 control slides contain a mixture of apoptotic (positive) and normal (negative) cells. In determining the amount of labeling reaction mixture to prepare, two control slides count as two samples.
      • Incubation time for proteinase K, DNase I, and labeling may need to be empirically determined for your particular cell type and slide preparation. Use this protocol as a guideline.
      • The use of coverslips is recommended during the labeling step of samples on slides to assure even distribution of the reaction mixture and to prevent loss due to evaporation during incubation. To make a coverslip, cut a piece of parafilm® just slightly larger than the specimen. Fold up one corner of the parafilm® to aid in its application and removal.
      • To construct a humidified chamber, wet several paper towels with water and place them along the bottom of a glass or plastic container with sides. Place two pipets parallel to each other on top of the towels. Keeping slides level, lay them face up across the pipets. To avoid unwanted drainage of reagents from slides make sure that the towels do not contact the slides in any way. Cover the container with a lid or plastic wrap to provide a humidified environment.
      • Cells grown in suspension can be fixed and attached to slides as follows. Pellet cells by gentle centrifugation (1000 rpm) for 5 min at 4°C. Discard the media and resuspend cells in 4% formaldehyde (in 1X PBS) at a cell density of 1x106/ml and incubate at room temperature for 10 min. Pellet cells as above, remove the fixative solution and resuspend, at the same concentration, in 80% ethanol. Store fixed cells at 4°C. Fixed cells (100-300 µl) can be immobilized onto glass slides by directly placing the cell suspension onto the slide or by using a Cytospin®. Precoating slides with poly-L-lysine may enhance cell adherence
      Detailed protocolA separate protocol has been provided for the end labeling of paraffin-embedded tissue sections, tissue cryosections, cell preparations fixed on slides, and cell suspensions for flow cytometry. See the section appropriate to your sample. HL-60 control slides should be labeled using the fixed cells protocol.

      A. PARAFFIN EMBEDDED TISSUE

      Deparaffinisation and Rehydration

      1. Immerse slides in xylene for 5 min at room temperature. Repeat using fresh xylene for a second 5 min incubation.
      1. Immerse slides in 100% ethanol for 5 min at room temperature. Repeat using fresh 100% ethanol for a second 5 min incubation.
      2. Immerse slides in 90% ethanol for 3 min at room temperature.
      3. Immerse slides in 80% ethanol for 3 min at room temperature.
      4. Immerse slides in 70% ethanol for 3 min at room temperature.
      5. Rinse slides briefly with 1X TBS and carefully dry the glass slide around the specimen.

      Note: At this point it may be helpful to encircle the specimen using a waxed pen or a hydrophobic slide marker.

      Note: DO NOT LET THE SPECIMEN DRY OUT DURING OR BETWEEN ANY STEP!!! (if necessary, cover or immerse the specimen in 1X TBS to keep hydrated)

      Permeabilization of Specimen

      1. Dilute 2 mg/ml Proteinase K 1:100 in 10 mM Tris pH 8 (mix 1 µl of 2 mg/ml Proteinase K plus 99 µl 10 mM Tris per specimen).
      2. Cover the entire specimen with 100 µl of 20 µg/ml proteinase K. Incubate at room temperature for 20 min. DO NOT OVERINCUBATE.
      3. Rinse slide with 1X TBS.
      4. Gently tap off excess liquid and carefully dry the glass slide around the specimen.

      Generation of a Positive Control (optional)

      1. Cover the entire specimen with 1 µg/µl DNase I in 1X TBS/1 mM MgSO4. Incubate at room temperature for 20 min.
      2. Rinse slide with 1X TBS.
      3. Gently tap off excess liquid and carefully dry the glass slide around the specimen.

      Note: A negative control can be generated by substituting dH2O for the TdT enzyme in the reaction mixture or by keeping the specimen in 1X reaction buffer (with a coverslip) during the labeling step.

      Equilibration and Labeling Reaction

      1. Dilute 5X TdT Equilibration Buffer 1:5 with dH2O (mix 20 µl 5X Buffer with 80 µl dH2O per specimen).
      2. Cover the entire specimen with 100 µl of 1X TdT Equilibration Buffer. Incubate at room temperature for 10 to 30 min while preparing the labeling reaction mixture.

      note: Alternatively slides can be immersed in a coplin jar containing enough 1X TdT buffer to cover the specimen. Do NOT allow the specimens to dry out.

      3. Prepare the working TdT Labeling Reaction Mixture as follows:
      lightly vortex contents of the Fluorescein-FragEL™ TdT Labeling Reaction Mix tube for each sample to be labeled, transfer to a clean microfuge tube ON ICE and mix gently:
      57.0 µl Fluorescein-FragEL™ TdT Labeling Reaction Mix
      3 µl TdT Enzyme

      4. Carefully blot the 1X equilibration buffer from the specimen, taking care not to touch the specimen.
      5. Immediately apply 60 µl of TdT Labeling Reaction Mixture (prepared above) onto each specimen.
      6. Cover the specimen with a piece of parafilm® cut slightly larger than the specimen. HINT: Folding up one corner of the parafilm® coverslip will aid in its application and removal.

      Note: The use of a coverslip assures even distribution of the reaction mixture and prevents loss due to evaporation during incubation.

      7. Place slides in a humidified chamber and incubate at 37°C for 1-1.5 h.

      Termination and Evaluation

      1. Remove parafilm® coverslip and incubate slides in 1X TBS for 1 min at room temperature.
      2. Briefly blot off excess liquid and incubate slides in fresh 1X TBS for 1 min at room temperature.
      3. Repeat step 2.
      4. Wipe excess TBS from back of slide and around specimen.
      5. Mount a glass coverslip using Fluorescein-FragEL™ Mounting Media.
      6. Wipe excess mounting media from edges of coverslip. Seal edges with nail polish.
      7. The total cell population may be visualized using a filter for DAPI, 330-380 nm.
      8. Analyze labeled nuclei by using a standard fluorescein filter, 465-495 nm.
      9. Store mounted samples at 4°C in the dark.

      B. TISSUE CRYOSECTIONS

      • This protocol is similar to FragEL™ of paraffin-embedded tissue sections EXCEPT that the deparaffinization step is replaced with a short hydration step and permeabilization with proteinase K is performed for only 10 min. Fixation of cryopreserved tissue is required prior to performing the assay.

      • To avoid loss of tissue from glass slides during washing steps, it is recommended that slides be dipped 2-3 times into a beaker of 1X TBS rather than rinsed with a wash bottle.

      • DO NOT LET THE SPECIMEN DRY OUT BETWEEN OR DURING ANY STEP!!! (if necessary cover or immerse the slide in 1X TBS to keep hydrated).

      Tissue Fixation and Hydration

      1. Immerse slides in 4% formaldehyde (in 1X PBS) for 15 min at room temperature.
      2. Gently tap off excess liquid and carefully dry the glass slide around the specimen.
      3. Immerse slides in 1X TBS for 15 min at room temperature.
      4. Carefully dry the glass slide around the specimen.

      Note: At this point it may be helpful to encircle the specimen using a waxed pen or a hydrophobic slide marker.

      Permeabilization of Specimen

      1. Dilute 2 mg/ml proteinase K 1:100 in 10 mM Tris pH 8 (mix 1 µl of 2 mg/ml Proteinase K plus 99 µl 10 mM Tris per specimen).
      2. Cover the entire specimen with 50-100 µl of 20 µg/ml proteinase K. Incubate at room temperature for 10 min. DO NOT OVERINCUBATE.
      3. Dip slide 2-3 times into a beaker of 1X TBS.
      4. Gently tap off excess liquid and carefully dry the glass slide around the specimen.

      Equilibration and Labeling Reaction Termination and Evaluation are identical to those outlined for Fluorescein-FragEL™ of parraffin-embedded tissue sections.

      Note: REMEMBER to wash slides by dipping into a beaker of 1X TBS rather than using a wash bottle.

      C. CELL SUSPENSIONS FOR FLOW CYTOMETRY

      Cell Fixation

      1. Pellet cells by centrifugation at 1000 rpm for 5 min at 4°C. Remove cell culture media.
      2. Resuspend cells in 4% formaldehyde/PBS at a cell density of 1x106/ml and incubate at room temperature for 10 min.
      3. Pellet cells by centrifugation at 1000 rpm for 5 min at 4°C. Remove formaldehyde/PBS.
      4. Resuspend cells at the same concentration in 80% ethanol.
      5. Store fixed cells at 4°C. (Fixed cells are stable for 2-6 months). Alternatively fixed cells can be immobilized onto glass slides by directly placing the cell suspension onto a slide or by using a Cytospin®. Precoating slides with poly-L-lysine may enhance cell adherence. Store cytospun samples at -20°C.

      Rehydration

      1. Transfer 1 ml of fixed cells (at 1 X 106 cells/ml) to a microcentrifuge tube.
      2. Pellet cells by centrifugation at 1000 rpm for 5 min at room temperature. Remove ethanol.
      3. Resuspend cells in 200 µl 1 X TBS. Incubate 10-15 min at room temperature.
      4. Pellet cells by centrifugation at 1000 rpm for 5 min at room temperature. Remove TBS.

      Permeabilization of Specimen

      1. Dilute 2 mg/ml proteinase K 1:100 in 10 mM Tris pH 8 (mix 1 µl of 2 mg/ml Proteinase K plus 99 µl 10 mM Tris per specimen).
      2. Resuspend cells in 100 µl of 20 µg/ml proteinase K. Incubate at room temperature for 5 min. DO NOT OVERINCUBATE.
      3. Pellet cells by centrifugation at 1000 rpm for 5 min at room temperature. Remove proteinase K.

      Equilibration and Labeling Reaction

      1. Dilute 5X TdT Equilibration Buffer 1:5 with dH2O (mix 20 µl 5X Buffer with 80 µl dH2O per specimen).
      2. Resuspend cells in 100 µl of 1X TdT Equilibration Buffer. Incubate at room temperature for 10 to 30 min while preparing the labeling reaction mixture.
      3. Prepare the working TdT Labeling Reaction Mixture as follows:
      gently vortex contents of the Fluorescein-FragEL™ TdT Labeling Reaction Mix tube for each sample to be labeled, transfer to a clean microfuge tube ON ICE and mix gently:
      i. 57.0 µl Fluorescein-FragEL™ TdT Labeling Reaction Mix
      ii. 3 µl TdT Enzyme

      4. Pellet cells by centrifugation at 1000 rpm for 5 min at room temperature. Remove buffer.
      5. Resuspend cells in 60 µl of TdT Labeling Reaction Mixture (prepared above). Incubate at 37°C for 1-1.5 h in the dark.

      Termination and Evaluation

      1. Pellet cells by centrifugation at 1000 rpm for 5 min at room temperature. Remove reaction mix.
      2. Resuspend cells in 200 µl 1 X TBS. Repeat TBS wash.
      3. Resuspend cells in a final volume of 0.5 ml 1 X TBS.
      4. Analyze cells on a flow cytometer equipped with a 488 nm argon ion laser source.

      Note: Cells labeled in suspension can also be fixed onto a glass slide and evaluated by fluorescence microscopy.

      D. CELL PREPARATIONS FIXED ON SLIDES

      • This protocol is similar to FragEL™ of tissue cryosections EXCEPT that permeabilization with proteinase K is performed for only 5 min. For fixation of cells grown in suspension before immobilization onto glass slides see Precautions and Rcommendations.

      • To avoid loss of cells from glass slides during washing steps, it is recommended that slides be dipped 2-3 times into a beaker of 1X TBS rather than rinsed with a wash bottle.

      • Reagent volumes may be decreased to account for the lower surface area that usually accompanies cells fixed on slides. DO NOT LET THE CELLS DRY OUT BETWEEN OR DURING ANY STEP!!! (if necessary cover or immerse the slide in 1X TBS to keep hydrated).

      • HL-60 control slides contain a mixture of apoptotic (positive) and normal (negative) cells. In determining the amount of labeling reaction mixture to prepare, two control slides count as one sample

      Rehydration

      1. Immerse slides in 1X TBS for 15 min at room temperature.
      2. Carefully dry the glass slide around the specimen.

      Note:At this point it may be helpful to encircle the specimen using a waxed pen or a hydrophobic slide marker.

      Permeabilization of Specimen

      1. Dilute 2 mg/ml proteinase K 1:100 in 10 mM Tris pH 8 (mix 1 µl of 2 mg/ml Proteinase K plus 99 µl 10 mM Tris per specimen).
      2. Cover the entire specimen with 50-100 µl of 20 µg/ml proteinase K. Incubate at room temperature for 5 min. DO NOT OVERINCUBATE.
      3. Dip slide 2-3 times into a beaker of 1X TBS.
      4. Gently tap off excess liquid and carefully dry the glass slide around the specimen.

      Equilibration and Labeling Reaction
      Termination and Evaluation       are identical to those steps outlined for paraffin-embedded tissue sections.


      Note; REMEMBER to wash slides by dipping into a beaker of 1X TBS rather than using a wash bottle.
      CalculationsEvaluation of Results using Fluorescence Microscopy A DAPI filter (ex 330-380 nm) can be used to visualize the total cell population. Using a fluorescein filter (ex 465-495 nm) a bright green signal indicates positive staining while dull green/red or hard to visualize cells signifies a non-reactive cell. Since the 3'-OH ends of DNA fragments generated by apoptosis are concentrated within the nuclei and apoptotic bodies, morphology as well as fluorescein staining can be used to interpret FragEL™ results. Characteristic morphological changes during apoptosis have been well characterized (see below) and should be used as verification of programmed cell death. Non-apoptotic cells do not incorporate significant amounts of labeled nucleotide since they lack an excess of 3'-OH ends. After labeling, carefully evaluate the control slides provided in the FragEL™ kit using a fluorescence microscope. The control slides contain a mixture of normal and apoptotic cells. Non-apoptotic cells should be predominantly rounded and appear faintly dull green/red or may be hard to visualize. A small number of cells naturally die during culturing or may be damaged during processing steps. Actinomycin D (Act D) induces apoptosis by inhibiting RNA synthesis. Distinctive changes in cell shape take place within HL-60 cells that have been treated with Act D. Nuclear chromatin condenses and aggregates to the inner surface of the nuclear membrane. The nuclear membrane convolutes followed by a budding-off process resulting in production of discrete apoptotic bodies. These nuclear changes are accompanied by protrusion or blebbing of the cell membrane that should be readily observable in the bright green apoptotic (positive) cells. In tissue sections, convoluted budding and blebbing of the cell membrane is rarely seen. Many apoptotic nuclei are roughly rounded or oval in shape. Well preserved apoptotic bodies may be present. Since apoptosis is an asynchronous event, apoptotic cells within a tissue may be scattered throughout the cell population rather than located in groups of contiguous cells as observed with necrosis. Additionally, cytoplasmic or diffuse overall staining is often seen in necrotic cells due to loss of membrane integrity. Evaluation of Results using Flow Cytometry Analyze suspension cells labeled with the Fluorescein-FragEL™ DNA Fragmentation Detection Kit on a flow cytometer equipped with a 488 nm Argon Ion Laser as the light source. The emission wavelength of fluorescein is 517 nm. To set up the flow cytometer use both apoptosis-induced and untreated cells. A sample single parameter histogram is shown on the bottom of image 5. The presence of apoptotic cells in the right hand panel is demonstrated by increased fluorescence intensity along the x-axis due to the incorporation of fluorescein nucleotides onto fragmented DNA. The vertical bound (dotted line) was placed using the histogram of untreated cells. A small percentage of normal cell death should be expected in routine cultures of untreated cells. Alterations in light scattering properties as measured by flow cytometry can also be used to monitor cells undergoing apoptosis. For example most untreated suspension cells exhibit high forward scatter. Upon induction of apoptosis, cell shrinkage and membrane blebbing occurs and a marked increase in side scatter is observed. A combination of changes in light scatter and fragment end labeling with fluorescein may be used to confirm or support conclusions drawn from measurements of a single parameter. Generation of Control Samples A negative control of your specific sample can be generated by substituting dH2O for the TdT in the reaction mixture or by keeping the specimen in 1X reaction buffer (with a coverslip for samples on slides) during the labeling step. Perform all other steps as described. A non-apoptotic control is also critical since cells and tissue begin to undergo apoptosis from the very beginning of the excision, fixation, and processing steps. A delay in fixation or routine mechanical manipulation may result in the unwanted breakage of DNA that could be misinterpreted as apoptosis. A positive control of your specific tissue sample can be generated by covering the entire specimen with 1 µg/µl DNase I in 1X TBS/1mM MgSO4 following proteinase K treatment. Incubate at room temperature for 20 min. Perform all other steps as described. Cytoplasmic as well as nuclear fluorescein staining of DNase treated cells may be observed.
      Assay characteristics and examplesFluorescein-FragEL™ staining of cell preparations fixed on slides and in suspension has been validated in Calbiochem® lab using several in vitro models of apoptosis including UV irradiation and actinomycin D-induced death of Daudi or HL-60 cells and Fas-mediated apoptosis of Jurkat cells. Agarose gel electrophoresis was used to verify the presence of DNA laddering in the UV and actinomycin D treated cultures. The following types of tissues were used to validate Fluorescein-FragEL™ staining: human colon and breast carcinoma, normal lymph node and tonsil, mouse thymus and staged mouse embryos.

      Figure 2: DNA Ladder

      Agarose gel electrophoresis of DNA isolated from promyelocytic leukemia cells (HL-60) using the ORP Suicide-Track™ DNA Ladder Isolation Kit (Cat. No. AM41). HL-60 cells were either untreated (Lane 1) or treated with 0.5 µg/ml Actinomycin D (Lane 2). DNA markers (M) were electrophoresed as a base pair reference.


      Figure 3: Apoptosis of HL-60 Cells by Fluorescence Microscopy

      Fluorescein-FragEL™ Staining of normal and apoptotic HL-60 cells induced to undergo apoptosis with 0.5 µg/ml Actinomycin D. Cells were fixed and deposited on glass slides using a cytospin. Analysis was performed using fluorescence microscopy.


      Figure 4: Apoptosis of HL-60 Cells by Flow Cymtometry

      Fluorescein-FragEL™ Staining of normal (Left Panel) and HL-60 cells induced to undergo apoptosis with 0.5 µg/ml Actinomycin D (Right Panel). Cells were fixed and labeled using the protocol for cells in suspension. Analysis of 5000 cells was performed by flow cytometry.


      Figure 5: Detection of Fas-Mediated Apoptosis by Flow Cytometry

      Jurkat cells were incubated with anti-Fas in the presence or absence of Caspase-1 Inhibitor III for various amounts of time. Cells were fixed and evaluated for DNA strand breakage using the Fluorescein-FragEL™ kit. Incorporation of fluorescein labeled nucleotides was quantified by flow cytometric analysis of 5000 cells. Inhibition of Caspase-1 blocks apoptosis.
      Registered TrademarksCalbiochem® is a registered trademark of EMD Chemicals, Inc.
      Cytospin® is a registered trademark of Shandon Lipshaw.
      Parafilm® is a registered trademark of the American National Can Company
      FragEL™, Suicide-Track™, and Interactive Pathways™ are trademarks of EMD Chemicals, Inc.