ChIP H3K27me3 Human Rat

Cells are sourced from various tissues to grow them in in-vitro conditions. Therefore, cell specific nutrients are important for their survival, maintenance and growth. Determining the appropriate cell culture media is a challenge if you are growing a cell line or a microorganism for the first time. Established cell lines, primary cells, stem cells, bacteria and Yeast all require varied nutrients from basic to complex. Based on the cell type, one can easy find what media and nutrients your peers have used before you try to reinvent the wheel.

Site-directed mutagenesis (SDM) can be challenging, particularly during detection/confirmation of (SDM) in colonies by sequencing or PCR techniques. This common issue in SDM is heavily relying on designing of mutagenic primer pairs. The best solution is to design the mutagenic primers that have extended 3'-ends/3'-overhang. This would provide the annealing region between the mutagenic primer pair is essentially shorter. and hence ensure a lower annealing temperature for the primer pair along with a higher chance of annealing to the template.

TUNEL assay is the cell death detection method where the biochemical marker of apoptosis is DNA fragmentation. The assay involves the microscopical detection of generated DNA fragments with free 3'-hydroxyl residues. in apoptotic cells using enzyme terminal deoxynucleotidyl transferase (TdT) which adds biotinylated nucleotides at the site of DNA breaks. Major challenges of this method involve proper access of the enzyme which could be hampered by poor permeabilization and/or excessive fixation with cross-linking fixative (common with archival tissue). This issue can be resolved by optimizing the incubation time with Proteinase K or CytoninTM.

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.

As autophagy is a multi-step process which includes not just the formation of autophagosomes, but most importantly, flux through the entire system, including the degradation upon fusion with lysosomes, which makes it quite challenging for detection. There are several methods for detection in mammalian cells, including immunoblotting analysis of LC3 and p62 and detection of autophagosome formation/maturation by fluorescence microscopy, Currently, there is no single “gold standard” for determining the autophagic activity that is applicable in every experimental context, hence it is recommended to go for the combined use of multiple methods to accurately assess the autophagic activity in any given biological setting.

As autophagy is a multi-step process which includes not just the formation of autophagosomes, but most importantly, flux through the entire system, including the degradation upon fusion with lysosomes, which makes it quite challenging for detection. There are several methods for detection in mammalian cells, including immunoblotting analysis of LC3 and p62 and detection of autophagosome formation/maturation by fluorescence microscopy, Currently, there is no single “gold standard” for determining the autophagic activity that is applicable in every experimental context, hence it is recommended to go for the combined use of multiple methods to accurately assess the autophagic activity in any given biological setting.

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.

ELISA is the most commonly used method of detecting and quantifying the concentration of an antigen in an unknown sample. During the experiment, If you get a weak signal, then make sure reagents are at room temperature before starting the assay. Try increasing incubation times to ensure maximal antibody binding and amplify the signal. Secondly, if you get values above 0 in the negative control indicates a high background signal. Try to consider reducing your antibody concentration and prevent non-specific binding of antibodies by using affinity-purified antibody and suitable blocking buffers. To avoid high well to well variation, do not stack plates during incubation, no bubbles in the plate and wash wells thoroughly to avoid variation.

Cell Invasion or Cell Migration assays are technically challenging to set up as the gradient between the two compartments equilibrates in time during the assay. It is also problematic to view cells and for cells to migrate through a non-physiologic polycarbonate or polypropylene filter. Care must be taken while loading the well with cells to form a single cell suspension. Precaution must be taken while trypsinization (under-trypsinization can lead to cell clumping while over-trypsinization could strip off adhesion molecules necessary for migration). This leads to difficulty in getting significant results, when only small numbers of cells cross the filter or when the distribution and/or staining of the cells is uneven.

Western blotting is a widely used technique to size separate proteins from a pool of cell or tissue lysates. The technique has 4 major steps: a) gel electrophoresis, b) blocking and treatment with antigen specific antibody, c) treatment with secondary antibody and finally d) detection and visualization. Though western blotting is a widely used technique, detection of specific proteins depends on several factors, the major ones are antibody concentration, incubation time and washing steps. Key points for obtaining clean blots are: always prepare fresh buffer solutions and optimize antibody concentration. Given the advent of high-throughput protein analysis and a push to limit the use of lab consumables, onestep antibodies are developed which recognise protein of interest and also contain a detection label.