Bacterial culture is a process of letting bacteria multiply in a controlled fashion (temperature, humidity, oxygen content or shaking), in a predetermined culture medium (antibiotic resistance to obtain homogenous clones). It is an important step, especially during cloning, as a single cell can be grown homogeneously (on semi-solid or in liquid conditions) to obtain colonies. As mentioned, bacteria can be cultured in broth cultures (Luria broth or LB) or Petri dishes (Agar plates). A specific antibiotic can be added to the broth or agar plates in order to grow bacteria which have the gene insert conferring its resistance to that antibiotic. Following points are necessary to consider for optimal growth conditions: 1. In general, most bacteria grow well at 37C, but there are some strains which require growth temperatures between 25-30C. 2. It is ideal in broth cultures to fill the flask to ⅓ or less of the total flask volume for optimal aerobic growth. 3. Shaking speeds between 140-180 rpm are appropriate to ensure aeration and that the cells are surrounded by fresh media, and do not settle.
Bacterial culture is a process of letting bacteria multiply in a controlled fashion (temperature, humidity, oxygen content or shaking), in a predetermined culture medium (antibiotic resistance to obtain homogenous clones). It is an important step, especially during cloning, as a single cell can be grown homogeneously (on semi-solid or in liquid conditions) to obtain colonies. As mentioned, bacteria can be cultured in broth cultures (Luria broth or LB) or Petri dishes (Agar plates). A specific antibiotic can be added to the broth or agar plates in order to grow bacteria which have the gene insert conferring its resistance to that antibiotic. Following points are necessary to consider for optimal growth conditions: 1. In general, most bacteria grow well at 37C, but there are some strains which require growth temperatures between 25-30C. 2. It is ideal in broth cultures to fill the flask to ⅓ or less of the total flask volume for optimal aerobic growth. 3. Shaking speeds between 140-180 rpm are appropriate to ensure aeration and that the cells are surrounded by fresh media, and do not settle.
Transfection is a powerful technique that enables the study of the function of genes and gene products in cells. Based on the nature of experiments, we may need a stable DNA transfection in cells for persistent gain-of-function or loss-of-function of the target gene. For stable transfection, integration of a DNA vector into the chromosome is crucial which requires selective screening and clonal isolation. By carefully selecting a viral delivery system and related reagents we can ensure safe and highly-efficient delivery of expression constructs for high-level constitutive or inducible expression in any mammalian cell type.
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.
Isolating DNA from tissues and paraffin-embedded tissue samples can be challenging as double-stranded DNA is physically fragile and highly susceptible to exo- and endonucleases. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in the presence of DNAse inhibitors. Further, extracting DNA from the nucleus need specific methods by combining physical, mechanical and chemical lysis approaches,
Isolating DNA from tissues and paraffin-embedded tissue samples can be challenging as double-stranded DNA is physically fragile and highly susceptible to exo- and endonucleases. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in the presence of DNAse inhibitors. Further, extracting DNA from the nucleus need specific methods by combining physical, mechanical and chemical lysis approaches,
Isolating DNA from tissues and paraffin-embedded tissue samples can be challenging as double-stranded DNA is physically fragile and highly susceptible to exo- and endonucleases. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in the presence of DNAse inhibitors. Further, extracting DNA from the nucleus need specific methods by combining physical, mechanical and chemical lysis approaches,
Isolating DNA from tissues and paraffin-embedded tissue samples can be challenging as double-stranded DNA is physically fragile and highly susceptible to exo- and endonucleases. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in the presence of DNAse inhibitors. Further, extracting DNA from the nucleus need specific methods by combining physical, mechanical and chemical lysis approaches,
Isolating DNA from tissues and paraffin-embedded tissue samples can be challenging as double-stranded DNA is physically fragile and highly susceptible to exo- and endonucleases. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in the presence of DNAse inhibitors. Further, extracting DNA from the nucleus need specific methods by combining physical, mechanical and chemical lysis approaches,
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