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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.

Hello! I used Trizol to extract total RNA from in-vitro cultured bacteria (1 X 10^8 cells). After phase separation, I mixed ~0.4 ml of the upper phase which contains RNA with 0.5 mL cold isopropanol. However, the amount of RNA when measured in Nanodrop was very low. In addition, the ratio between 260 and 230 was around 0.1 to 0.5. Is there a chance that my sample was contaminated by the Trizol reagent? When I collected the aqueous phase I made sure to not touch the lower phase. What should I do?

Flow cytometry is an immunophenotyping technique whereby sing cell suspensions are stained for either cell surface markers or intracellular proteins by fluorescently-labelled antibodies and analyzed with a flow cytometer, where fluorescently-labelled molecules are excited by the laser to emit light at varying wavelengths, which is then detected by the instrument. There are several key criteria which are required to be kept in mind while designing a flow experiment- 1. Antibody titration (optimal dilution of antibodies should be calculated in order to avoid over- or under- saturated signals for proper detection of surface and intracellular markers), 2. Precision (3 or more replicates of the sample should be used per experiment), 3. Specificity (proper isotype controls should be included in the experiment), 4. Day-to-day variability (experiments should be repeated 3 or more times to ensure consistency and avoid variability due to flow cytometer settings), 5. Antibody interaction (Fluorescence minus one or FMO should be used, which is the comparison of signals from panel minus one antibody vs. the full panel), and 6. Antibody stability (fluorescently-labelled antibodies should be stored at 4C).

Flow cytometry is an immunophenotyping technique whereby sing cell suspensions are stained for either cell surface markers or intracellular proteins by fluorescently-labelled antibodies and analyzed with a flow cytometer, where fluorescently-labelled molecules are excited by the laser to emit light at varying wavelengths, which is then detected by the instrument. There are several key criteria which are required to be kept in mind while designing a flow experiment- 1. Antibody titration (optimal dilution of antibodies should be calculated in order to avoid over- or under- saturated signals for proper detection of surface and intracellular markers), 2. Precision (3 or more replicates of the sample should be used per experiment), 3. Specificity (proper isotype controls should be included in the experiment), 4. Day-to-day variability (experiments should be repeated 3 or more times to ensure consistency and avoid variability due to flow cytometer settings), 5. Antibody interaction (Fluorescence minus one or FMO should be used, which is the comparison of signals from panel minus one antibody vs. the full panel), and 6. Antibody stability (fluorescently-labelled antibodies should be stored at 4C).

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.

DNA damage assay is a standard method for determining in-vivo/in-vitro genotoxicity by measuring the breaks in the DNA chain of animal and plant cells. Initial DNA damage leads to cell cycle arrest and, at the final stages, leads to induction of senescence or cell death (apoptosis, necrosis, autophagy, or mitotic catastrophe). Detection of DNA damage from mild to moderate to severe is challenging when studying genotoxicity in the pool of cells. It is favorable to use DNA damage assay kits available for prominent identification of the extent of damage in the analysis.