RNA isolation / purification Cells immortalized

Gene silencing through the use of small interfering RNA (siRNA) has become a primary tool for identifying disease-causing genes. There are several aspects for preparing and delivering effective siRNA to knockdown a target gene. The length of siRNA should be 21–23nt long with G/C content 30–50%. If a validated siRNA sequence for your target gene is not available, use siRNA generated against the entire target gene ORF. Always work with two or three different siRNA constructs to get reliable results. If you are not sure how much siRNA to use for a given experiment, start with a transfection concentration of 10-50 nM and use siRNA-specific transfection reagent to ensure efficient siRNA delivery in a wide range of cells.

Gene silencing through the use of small interfering RNA (siRNA) has become a primary tool for identifying disease-causing genes. There are several aspects for preparing and delivering effective siRNA to knockdown a target gene. The length of siRNA should be 21–23nt long with G/C content 30–50%. If a validated siRNA sequence for your target gene is not available, use siRNA generated against the entire target gene ORF. Always work with two or three different siRNA constructs to get reliable results. If you are not sure how much siRNA to use for a given experiment, start with a transfection concentration of 10-50 nM and use siRNA-specific transfection reagent to ensure efficient siRNA delivery in a wide range of cells.

Gene silencing through the use of small interfering RNA (siRNA) has become a primary tool for identifying disease-causing genes. There are several aspects for preparing and delivering effective siRNA to knockdown a target gene. The length of siRNA should be 21–23nt long with G/C content 30–50%. If a validated siRNA sequence for your target gene is not available, use siRNA generated against the entire target gene ORF. Always work with two or three different siRNA constructs to get reliable results. If you are not sure how much siRNA to use for a given experiment, start with a transfection concentration of 10-50 nM and use siRNA-specific transfection reagent to ensure efficient siRNA delivery in a wide range of cells.

Gene silencing through the use of small interfering RNA (siRNA) has become a primary tool for identifying disease-causing genes. There are several aspects for preparing and delivering effective siRNA to knockdown a target gene. The length of siRNA should be 21–23nt long with G/C content 30–50%. If a validated siRNA sequence for your target gene is not available, use siRNA generated against the entire target gene ORF. Always work with two or three different siRNA constructs to get reliable results. If you are not sure how much siRNA to use for a given experiment, start with a transfection concentration of 10-50 nM and use siRNA-specific transfection reagent to ensure efficient siRNA delivery in a wide range of cells.

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been greatly used for studies on embryonic development and cell differentiation.iPSCs provide a stable source for either self-renewal or differentiation into suitable cells when cultured in a particular environment. Pluripotent cell culture was originally started by deriving cells from inner cell mass (ICM) from pre-implanted blastocysts, these were called embryonic stem cells. These cells after isolation can be grown on traditional extracellular matrices (like mouse embryonic fibroblasts, MEFs) or feeder-free culture systems. DMEM/F12 has been the most commonly used basal media in the culture of pluripotent cells. These cells are cultured at normal atmospheric oxygen levels, 21%, however, some studies have proposed that 4% oxygen tension may be better for hESC growth. Higher D-glucose concentration (4.2g/l) and osmolarity (320mOsm) that mimics the natural environment of embryonic tissue are optimal for the growth of hESCs. Supplements like N2 and/or B-27, in the presence of growth factors like bFGF, have been shown to increase pluripotency of these cells. bFGF, FGF2 and other ligands of receptor tyrosine kinases like IGF are also required or maintain self-renewal ability of these cells. TGF𝛃1, by its activation of SMAD2/3 signalling, also represses differentiation of iPSCs. Other compounds like ROCK inhibitors reduce blebbing and apoptosis in these cells to maintain their clonogenicity. However, an inhibitor for LIF (leukaemia inhibitory factor, which is one of the pluripotent genes) has an opposing effect. Therefore, it is important to understand the culture conditions and media composition that affect downstream signalling in hESCs or iPSCs that may lead to their differentiation.

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been greatly used for studies on embryonic development and cell differentiation.iPSCs provide a stable source for either self-renewal or differentiation into suitable cells when cultured in a particular environment. Pluripotent cell culture was originally started by deriving cells from inner cell mass (ICM) from pre-implanted blastocysts, these were called embryonic stem cells. These cells after isolation can be grown on traditional extracellular matrices (like mouse embryonic fibroblasts, MEFs) or feeder-free culture systems. DMEM/F12 has been the most commonly used basal media in the culture of pluripotent cells. These cells are cultured at normal atmospheric oxygen levels, 21%, however, some studies have proposed that 4% oxygen tension may be better for hESC growth. Higher D-glucose concentration (4.2g/l) and osmolarity (320mOsm) that mimics the natural environment of embryonic tissue are optimal for the growth of hESCs. Supplements like N2 and/or B-27, in the presence of growth factors like bFGF, have been shown to increase pluripotency of these cells. bFGF, FGF2 and other ligands of receptor tyrosine kinases like IGF are also required or maintain self-renewal ability of these cells. TGF𝛃1, by its activation of SMAD2/3 signalling, also represses differentiation of iPSCs. Other compounds like ROCK inhibitors reduce blebbing and apoptosis in these cells to maintain their clonogenicity. However, an inhibitor for LIF (leukaemia inhibitory factor, which is one of the pluripotent genes) has an opposing effect. Therefore, it is important to understand the culture conditions and media composition that affect downstream signalling in hESCs or iPSCs that may lead to their differentiation.

An alternative to culture-based cell death detection is an assessment of other cell viability indicators using fluorescent dyes, including membrane potential and membrane integrity. Live/Dead assays differentiates live and dead cells using membrane integrity as a proxy for cell viability and are based on a fluorescent staining procedure followed by detection using flow cytometry. However, samples preparation for such flow cytometry-based techniques could be challenging. Cell harvesting by trypsinization, mechanical or enzymatic cell disaggregation from tissues, extensive centrifugation steps, may all lead to preferential loss of apoptotic cells. To overcome this strictly follow manufacturers instruction of the detection kit.

Get tips on using M-PER™ Mammalian Protein Extraction Reagent to perform Protein isolation Mammalian cells - Human aortic endothelial cells

An alternative to culture-based cell death detection is an assessment of other cell viability indicators using fluorescent dyes, including membrane potential and membrane integrity. Live/Dead assays differentiates live and dead cells using membrane integrity as a proxy for cell viability and are based on a fluorescent staining procedure followed by detection using flow cytometry. However, samples preparation for such flow cytometry-based techniques could be challenging. Cell harvesting by trypsinization, mechanical or enzymatic cell disaggregation from tissues, extensive centrifugation steps, may all lead to preferential loss of apoptotic cells. To overcome this strictly follow manufacturers instruction of the detection kit.

Protein expression refers to the techniques in which a protein of interest is synthesized, modified or regulated in cells. The blueprints for proteins are stored in DNA which is then transcribed to produce messenger RNA (mRNA). mRNA is then translated into protein. In prokaryotes, this process of mRNA translation occurs simultaneously with mRNA transcription. In eukaryotes, these two processes occur at separate times and in separate cellular regions (transcription in nucleus and translation in cytoplasm). Recombinant protein expression utilizes cellular machinery to generate proteins, instead of chemical synthesis of proteins as it is very complex. Proteins produced from such DNA templates are called recombinant proteins and DNA templates are simple to construct. Recombinant protein expression involves transfecting cells with a DNA vector that contains the template. The cultured cells can then transcribe and translate the desired protein. The cells can be lysed to extract the expressed protein for subsequent purification. Both prokaryotic and eukaryotic protein expression systems are widely used. The selection of the system depends on the type of protein, the requirements for functional activity and the desired yield. These expression systems include mammalian, insect, yeast, bacterial, algal and cell-free. Each of these has pros and cons. Mammalian expression systems can be used for transient or stable expression, with ultra high-yield protein expression. However, high yields are only possible in suspension cultures and more demanding culture conditions. Insect cultures are the same as mammalian, except that they can be used as both static and suspension cultures. These cultures also have demanding culture conditions and may also be time consuming. Yeast cultures can produce eukaryotic proteins and are scalable, with minimum culture requirements. Yeast cultures may require growth culture optimization. Bacterial cultures are simple, scalable and low cost, but these may require protein specific optimization and are not suitable for all mammalian proteins. Algal cultures are optimized for robust selection and expression, but these are less developed than other host platforms. Cell-free systems are open, free of any unnatural compounds, fast and simple. This system is however, not optimal for scaling up.