siRNA / miRNA gene silencing Human BC-1

Plasmid isolation is an important technique in molecular biology or any kind of genetic editing. It involves amplifying plasmids overnight by transforming them into competent bacterial cells. The desired colonies of these bacteria can then be grown in shaker cultures, at appropriate shaking speed, oxygen availability and temperature. These liquid cultures can then be ultracentrifuged to pellet the bacteria, which are then used for plasmid isolation. The bacteria are first resuspended in a buffer, then lysed, neutralized, purified in a column, eluted, precipitated with ethanol and then resuspended. During plasmid isolation, it is important to lyse cells quickly because lysing bacteria for too long may lead to irreversible denaturing of the plasmid. Usually, alkaline lysis is used for isolation because it is a mild treatment. It isolates plasmid DNA and other cell components such as proteins by breaking cells apart with an alkaline solution. Precipitation removes the proteins, and the plasmid DNA recovers with alcohol precipitation. Resuspension and lysis buffers should be mixed thoroughly in order to prevent the DNA from breaking into smaller fragments. This is because broken gDNA can reanneal and remain in the solution, without binding to the column.

Cell cytotoxicity assays measure the ability of certain compounds or chemical mediators to reduce the viability of the cells. The term cell cytotoxicity assay can sometimes be used interchangeably with cell proliferation assay. Healthy living cells can be identified by the use of formazan dyes, protease biomarkers or by measuring ATP content. The formazan dyes are chromogenic products formed by the reduction of tetrazolium salts by dehydrogenases, such as lactate dehydrogenase (LDH) and reductases that are released during cell death. Common tetrazolium salts include INT, MTT, MTS and XTT. Cell cytotoxicity can also be measured by using the SRB and WST-1 assays. These assays can usually be used in a high-throughput fashion and can be quantitated by measuring absorbance, colorimetry or luminescence. All these assays require similar numbers of cell plating at the initiation, a time course of treatment with the cytotoxic agent and at least triplicates for each condition at every point of analysis. Cell shrinkage, plasma membrane blebbing, cell detachment, externalization of phosphatidylserine, nuclear condensation and ultimately DNA fragmentation are well-described features of apoptosis. The assays that rely on cell membrane integrity for their function, may not be able to quantify early apoptosis. Therefore, in order to distinguish early apoptotic vs. late apoptotic or necrotic cells, additional flow cytometry techniques can be used. A combination of Annexin V and PI (propidium iodide) can be used to distinguish early (Annexin V+/PI-) and late apoptotic (Annexin V+/PI+) cells. Sometimes, caspase assays are used in order to differentiate the stages of apoptosis.

Get tips on using TIANamp Genomic DNA Kit to perform DNA isolation / purification Tissue - bone

Get tips on using Gentra Puregene Blood Kit to perform DNA isolation / purification Tissue - blood / plasma

Get tips on using QIAGEN Genomic-tip 20/G to perform DNA isolation / purification Plants - Leaves