The formation of DNA from an RNA template using reverse transcription leads to the formation of double-stranded complementary DNA or cDNA. The challenges with this process include 1. Maintaining the integrity of RNA, 2. Hairpin loops or other secondary structures formed by single-stranded RNA can also affect cDNA synthesis, and 3. DNA-RNA hybrids, which may result when the first strand of cDNA is formed. For the first challenge, using workflows that involve proper isolation and storage of RNA, and maintaining a nuclease-free environment helps obtain RNA with ideal 260/230 ratios. Using a reverse transcriptase that can tolerate high temperatures (50-55oC), overcomes obstacles imposed by secondary RNA structures. Finally, RNase H has the ability to hydrolyze RNA before the formation of a second cDNA strand. It is important to ensure that RNase H activity is optimal because higher RNase H activity leads to premature degradation of the RNA template. Many reverse transcriptases offer built-in RNase H activity.
Get tips on using GenJet™ In Vitro DNA Transfection Reagent to perform DNA transfection Mammalian cells - Immortalized cell lines COS7
Get tips on using GenJet™ In Vitro DNA Transfection Reagent to perform DNA transfection Mammalian cells - Immortalized cell lines MCF-7
The most widely used method for protein quantification is by spectrophotometry. The concentration of the protein in the samples is measured at an absorbance of 280 nm. The absorbance of the sample protein is then plotted against a standard curve. This method allows for total protein quantification in a sample (cell and tissue extracts). Before analysing the concentration of protein in the sample, it is important to choose the right test method. For high protein concentration samples (above 5 - 160 mg/ml) the best method is to use the Biuret test. For low concentrations samples (between 1 - 2000µg/ml) the best methods are Lowry assay, BCA assay, Bradford assay and coomassie blue (for exact sensitivity of the test kits you use, refer to manufacturer's protocol). If the samples contain detergents like Triton X-100 then BCA assay is the best choice. For samples that have proteins larger than 3 KDa in size Bradford assay is the best choice. Each method has advantages and disadvantages, plan your analysis considering your sample characteristics.
The most widely used method for protein quantification is by spectrophotometry. The concentration of the protein in the samples is measured at an absorbance of 280 nm. The absorbance of the sample protein is then plotted against a standard curve. This method allows for total protein quantification in a sample (cell and tissue extracts). Before analysing the concentration of protein in the sample, it is important to choose the right test method. For high protein concentration samples (above 5 - 160 mg/ml) the best method is to use the Biuret test. For low concentrations samples (between 1 - 2000µg/ml) the best methods are Lowry assay, BCA assay, Bradford assay and coomassie blue (for exact sensitivity of the test kits you use, refer to manufacturer's protocol). If the samples contain detergents like Triton X-100 then BCA assay is the best choice. For samples that have proteins larger than 3 KDa in size Bradford assay is the best choice. Each method has advantages and disadvantages, plan your analysis considering your sample characteristics.
Get tips on using Gibco™ DMEM/F-12, GlutaMAX™ supplement to perform Stem cell culture media Choroid plexus-like tissue generation from SFEBq
RNA quantification for appropriate concentration and quality (260/280 ratio) is an important step before downstream analysis (including sequencing, RT-qPCR, etc.). Having insufficient RNA quantities or a high salt or phenol in the RNA product can lead to variable or irreproducible downstream results. The various methods used for RNA quantification include: 1. UV spectrophotometric (challenges include: low sensitivity, cannot distinguish between nucleic acid species), 2. Fluorescence-based (challenges include: requires standards, cannot measure amplifiability, not sequence-specific), and 3. RT-PCR (challenges include: requires standards, time-intensive, costly). In order to overcome these challenges, and also to ensure the proper quantification and quality control for RNA product, it is important to use at least two or more methods in order to discard any inconsistencies. Using standards for calibrations increases the sensitivity range for RNA detention (fluorescence- and RT-PCR-based methods). When using RT- PCR, it is important to choose correct primers, aligning to the desired site on the template and of appropriate product length, along with positive, negative and loading controls. It is also important to have at least two primer pairs in order to confirm results.
RNA quantification for appropriate concentration and quality (260/280 ratio) is an important step before downstream analysis (including sequencing, RT-qPCR, etc.). Having insufficient RNA quantities or a high salt or phenol in the RNA product can lead to variable or irreproducible downstream results. The various methods used for RNA quantification include: 1. UV spectrophotometric (challenges include: low sensitivity, cannot distinguish between nucleic acid species), 2. Fluorescence-based (challenges include: requires standards, cannot measure amplifiability, not sequence-specific), and 3. RT-PCR (challenges include: requires standards, time-intensive, costly). In order to overcome these challenges, and also to ensure the proper quantification and quality control for RNA product, it is important to use at least two or more methods in order to discard any inconsistencies. Using standards for calibrations increases the sensitivity range for RNA detention (fluorescence- and RT-PCR-based methods). When using RT- PCR, it is important to choose correct primers, aligning to the desired site on the template and of appropriate product length, along with positive, negative and loading controls. It is also important to have at least two primer pairs in order to confirm results.
RNA quantification for appropriate concentration and quality (260/280 ratio) is an important step before downstream analysis (including sequencing, RT-qPCR, etc.). Having insufficient RNA quantities or a high salt or phenol in the RNA product can lead to variable or irreproducible downstream results. The various methods used for RNA quantification include: 1. UV spectrophotometric (challenges include: low sensitivity, cannot distinguish between nucleic acid species), 2. Fluorescence-based (challenges include: requires standards, cannot measure amplifiability, not sequence-specific), and 3. RT-PCR (challenges include: requires standards, time-intensive, costly). In order to overcome these challenges, and also to ensure the proper quantification and quality control for RNA product, it is important to use at least two or more methods in order to discard any inconsistencies. Using standards for calibrations increases the sensitivity range for RNA detention (fluorescence- and RT-PCR-based methods). When using RT- PCR, it is important to choose correct primers, aligning to the desired site on the template and of appropriate product length, along with positive, negative and loading controls. It is also important to have at least two primer pairs in order to confirm results.
Generally isolating RNA from Gram-negative bacteria is easy, however keeping your working environment clean and RNase free (use RNase inhibitor) is essential. Some common points to keep in mind: a) Use fresh samples for isolation or store them by freezing in RNA stabilizing buffer until use. b) Choose the bacterial input amounts carefully, to ensure buffer volumes are adequate and not to overload the columns.
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