Team:NJU China/Protocol
From 2013.igem.org
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- | <h2 id="April"> | + | <h2 id="April">RNA Extraction</h2> |
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- | <h2> | + | <h2>4. RT-PCR</h2> |
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- | <a> | + | <a>RNA Extraction</a> |
- | <span> | + | <span> |
+ | A:TRIzol Reagent (Invitrogen) _Instructions For RNA Isolation</br> | ||
+ | Caution: When working with TRIzol Reagent use gloves and eye protection (shield, safety goggles). Avoid contact with skin or clothing. Use in a chemical fume hood. Aviod breathing vapor. | ||
+ | </br>Unless otherwise stated, the procedure is carried out at 15 to 30°C, and reagent are at 15 to 30°C. | ||
+ | </br>Reagent required, but not supplied: | ||
+ | </br>Chloroform | ||
+ | </br>Isopropyl alcohol | ||
+ | </br>75% Ethanol (in DEPC-treated water) | ||
+ | </br>RNase-free water or 0.5% SDS solution [ To prepare RNase-free water, draw water into RNase-free galss bottles. Add diethylpyrocarbonate (DEPC) to 0.01% (v/v). Let stand overnight and autoclave. The SDS solution must be prepared using EDPC-treated, autoclaved water.] | ||
+ | </br>1. HOMOGENIZATION (see notes 1-3) | ||
+ | </br> a. Tissues | ||
+ | </br> Homogenize tissue samples in 1 ml of TRIzol Reagent per 50-100 mg of tissue using a galss-Teflon or power homogenizer (Polytron, or Tekmar’s TISSUMIZER or equivalent). The sample volume should not exceed 10% of the volume of TRIzol Reagent used for homogenization. | ||
+ | </br> b. Cells Grown in Monolayer | ||
+ | </br> Lyse cells directly in a culture dish by adding 1 ml of TRIzol Reagent to a 3.5 cm diameter dish, and passing the cell lysate several times through a pipette. The amount of TRIzol Reagent added is based on the area of the culture dish (1 ml per 10 cm2) and not on the number of cell present. An insufficient amount of TRIzol Reagent may result in contamination of the isolated RNA with DNA. | ||
+ | </br> c. Cells Grown in Suspension | ||
+ | </br> Pellet cells by centrifugation. Lyse cells in TRIzol Reagent by repetitive pipetting. Use 1 ml of the reagent per 5-10×106 of animal, plant or yeast cells, or per 1×107 bacterial cells. Washing cells before addition of TRIzol Reagent should be avoided as this increases the possibility of mRNA degradation. Disruption of some yeast and bacterial cells may require the use of a homogenizer. | ||
+ | </br> OPTIONAL: An additional isolation step may be required for samples with high content of proteins, fat, polysaccharides or extracellular material such as muscles, fat tissue, and tuberous parts of plants. Following homogenization, remove insoluble material from the homogenate by centrifugation at 12000×g for 10 minutes at 2 to 8°C. The resulting pellet contains extracellular membranes, polysaccharides, and high molecular weight DNA, while the supernatant contains RNA. In samples from fat tissue, an excess of fat collects as a top layer which should be removed. In each case, transfer the cleared homogenate solution to a fresh tube and proceed with chloroform addition and phase separation as described. | ||
+ | </br></br>2. PHASE SEPARATION | ||
+ | </br> Incubate the homogenized samples for 5 minutes at 15 to 30°C to permit the complete dissociation of nucleoprotein complexes. Add 0.2 ml of chloroform per 1 ml of TRIZOL Reagent. Cap sample tubes securely. Shake tubes vigorously by hand for 15 seconds and incubate them at 15 to 30°C for 2 to 3 minutes. Centrifuge the samples at no more than 12,000×g for 15 minutes at 2 to 8°C. Following centrifugation, the mixture separates into a lower red, phenol-chloroform phase, an interphase, and a colorless upper aqueous phase. RNA remains exclusively in the aqueous phase. The volume of the aqueous phase is about 60% of the volume of TRIZOL Reagent used for homogenization. | ||
+ | </br>3. RNA PRECIPITATION | ||
+ | </br></br> Transfer the aqueous phase to a fresh tube, and save the organic phase if isolation of DNA or protein is desired. Precipitate the RNA from the aqueous phase by mixing with isopropyl alcohol. Use 0.5 ml of isopropyl alcohol per 1 ml of TRIZOL Reagent used for the initial homogenization. Incubate samples at 15 to 30°C for 10 minutes and centrifuge at no more than 12,000×g for 10 minutes at 2 to 8°C. The RNA precipitate, often invisible before centrifugation, forms a gel-like pellet on the side and bottom of the tube. | ||
+ | </br></br>4. RNA WASH | ||
+ | </br> Remove the supernatant. Wash the RNA pellet once with 75% ethanol, adding at least 1 ml of 75% ethanol per 1 ml of TRIZOL Reagent used for the initial homogenization. Mix the sample by vortexing and centrifuge at no more than 7,500 × g for 5 minutes at 2 to 8°C. | ||
+ | </br></br>5. REDISSOLVING THE RNA | ||
+ | </br> At the end of the procedure, briefly dry the RNA pellet (air-dry or vacuum-dry for 5-10 minutes). Do not dry the RNA by centrifugation under vacuum. It is important not to let the RNA pellet dry completely as this will greatly decrease its solubility. Partially dissolved RNA samples have an A260/280 ratio < 1.6. Dissolve RNA in RNase-free water or 0.5% SDS solution by passing the solution a few times through a pipette tip, and incubating for 10 minutes at 55 to 60°C. (Avoid SDS when RNA will be used in subsequent enzymatic reactions.) RNA can also be redissolved in 100% formamide (deionized) and stored at -70°C (5). | ||
+ | RNA Isolation Notes: | ||
+ | </br>1. Isolation of RNA from small quantities of tissue (1 to 10 mg) or Cell (102 to 104) Samples: Add 800 μl of TRIZOL to the tissue or cells. Following sample lysis, add chloroform and proceed with the phase separation as described in step 2. Prior to precipitating the RNA with isopropyl alcohol, add 5-10 μg RNase-free glycogen (Cat. No 10814) as carrier to the aqueous phase. To reduce viscosity, shear the genomic DNA with 2 passes through a 26 gauge needle prior to chloroform addition. The glycogen remains in the aqueous phase and is co-precipitated with the RNA. It does not inhibit first-strand synthesis at concentrations up to 4 mg/ml and does not inhibit PCR. | ||
+ | </br>2. After homogenization and before addition of chloroform, samples can be stored at -60 to -70°C for at least one month. The RNA precipitate (step 4, RNA WASH) can be stored in 75% ethanol at 2 to 8°C for at least one week, or at least one year at –5 to -20°C. | ||
+ | </br>3. Table-top centrifuges that can attain a maximum of 2,600 × g are suitable for use in these protocols if the centrifugation time is increased to 30-60 minutes in steps 2 and 3. | ||
+ | </br></br>B:TRIzol LS Reagent_RNA Isolation Procedure | ||
+ | </br>Always use the appropriate precautions to avoid RNase contamination when preparing and handling RNA. | ||
+ | </br>RNA pricipitation | ||
+ | </br>1. (Optional) When precipitating RNA from small sample quantities(<106 cells or <10 mg tissue), add 5-10μg of RNase-free glycogen as a carrier to the aqueous phase. | ||
+ | Note: Glycogen is co-precipitated with the RNA, but does not inhibit first-strand synthesis at concentrations ≤4mg/mL, and does not inhibit PCR. | ||
+ | </br>2. Add 0.5mL of 100% isopropanol to the aqueous phase, per of 0.75 mL TRIzol LS Reagent used for homogenization. | ||
+ | </br>3. Incubate at room temperature for 10 minutes. | ||
+ | </br>4. Centrifuge at 12,000×g for 10 minutes at 4°C. | ||
+ | </br>Note: The RNA is often invisible prior to centrifugation, and forms a gel-like pellet on the side and bottom of the tube. | ||
+ | </br>5. Proceed to RNA wash and resuspension. | ||
+ | </br>RNA wash and resuspension | ||
+ | </br>1. Remove the supernatant from the tube, leaving only the RNA pellet. | ||
+ | </br>2. Wash the RNA pellet, with 1mL of 75% ethanol per 0.75 mL of TRIzol LS Reagent used for the initial homogenization. Vortex the sample to mix. | ||
+ | </br>3. Centrifuge the sample at 7500×g for 5 minutes at 4°C, and discard the supernatant. | ||
+ | </br>4. Vacuum or air dry the RNA pellet for 5-10 minutes. Do not dry the pellet by vacuum centrifuge. | ||
+ | </br>Note: Do not allow the RNA to dry completely, because the pellet can lose solubility. Partially dissolved RNA samples have an A260/280 ratio <1.6. | ||
+ | </br>5. Resuspend the RNA pellet in RNase-free water or 0.5% SDS solution (20-50μL) by passing the solution up and down several times through a pipette tip. | ||
+ | Note: Do not dissolve the RNA in 0.5% SDS if it is to be used in subsequent enzymatic reactions. | ||
+ | </br>6. Incubate in a water bath or heat block set at 55-60°C for 10-15 minutes. | ||
+ | </br>7. Proceed to downstream application, or store at -70°C. | ||
+ | </span> | ||
</h3> | </h3> | ||
</div> | </div> |
Revision as of 14:35, 27 September 2013