Site Directed Mutagenesis (SDM) Human Point mutation Caco-2

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.

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.

Stem cells have the unique ability to self-renew or differentiate themselves into various cell types in response to appropriate signals. These cells are especially important for tissue repair, regeneration, replacement, or in the case of hematopoietic stem cells (HSCs) to differentiate into various myeloid populations. Appropriate signals refer to the growth factor supplements or cytokines that mediate differentiation of various stem cells into the required differentiated form. For instance, HSCs can be differentiated into dendritic cells (with IL-4 and GM-CSF), macrophages (with m-CSF) and MDSCs (with IL-6 and GM-CSF). Human pluripotent stem cells (hPSCs) and induced pluripotent stem cells (iPSCs) can be first cultured in neural differentiation media (GSK3𝛃-i, TGF𝛃-i, AMPK-i, hLIF) to form neural rosettes, which can be differentiated into neural or glial progenitors (finally differentiated into oligodendrocytes). Neural progenitors can be finally differentiated into glutaminergic (dibytyryl cAMP, ascorbic acid) and dopaminergic (SHH, FGF-8, BDNF, GDNF, TGF-𝛃3) neurons. Thus, it is important to first identify the self-renewing cell line: its source and its final differentiation state, followed by the supplements and cytokines required for the differentiation, and final use. Timelines are another thing that is considered. For instance, it takes 7-10 days to form neural rosettes from iPSCs and 3 days to differentiate neural progenitors to neurons. Finally, the stability for stem cell culture media varies. It is advised to make fresh media every time when differentiating HSCs to myeloid populations, whereas neural differentiation media may remain stable for two weeks when stored in dark between 2-8C.

Get tips on using siGENOME Human GSK3A (2931) siRNA - SMARTpool to perform siRNA / miRNA gene silencing Human - PANC-1 GSK-3α

Wound healing assay can be challenging due to inconsistencies and variations while making a wound on the confluent cell monolayer, consequently leads to wounds of varying sizes and widths. Moreover, this assay causes damage to the cells that are at the edge of the wound, which can prevent cell migration into the wound site and healing. The best solution is to use the standard wound healing assay kits using either combs or inserts to make a defined wound field or gap and prevent the well-to-well variation in these assays.

Get tips on using siGENOME Human ATG12 (9140) siRNA - SMARTpool to perform siRNA / miRNA gene silencing Human - BT-20 Atg12

Get tips on using siGENOME Human RAB5A (5868) siRNA - SMARTpool to perform siRNA / miRNA gene silencing Human - BT-20 Rab5a

A restriction enzyme or restriction endonuclease is defined as a protein that recognizes a specific, short nucleotide sequence and cuts the DNA only at or near that site, known as restriction site or target sequence. The four most common types of restriction enzymes inclue: Type I (cleaves at sites remote from a recognition site), Type II (cleaves within or at short specific distances from a recognition site), Type III (cleave at sites a short distance from a recognition site), and Type IV (targets modified DNA- methylated, hydroxymethylated and glucosyl-hydroxymethylated DNA). The most common challenges with restriction digest include- 1. inactivation of enzyme, 2. incomplete or no digestion, and 3. unexpected cleavage. The enzyme should always be stored at -20C and multiple freeze-thaw cycles should be avoided in order to maintain optimal activity. Always use a control DNA digestion with the enzyme to ensure adequate activity (to avoid interference due to high glycerol in the enzyme). For complete digestion, make sure that the enzyme volume is 1/10th of the total reaction volume, optimal temperature is constantly maintained throughout the reaction, the total reaction time is appropriately calculated based on the amount of DNA to be digested, appropriate buffers should be used to ensure maximal enzymatic activity, and in case of a double digest, make sure that the two restriction sites are far enough so that the activity of one enzyme cannot interfere with activity of the other. Star activity (or off-target cleavage) and incomplete cleavage are potential challenges which may occur due to suboptimal enzymatic conditions or inappropriate enzyme storage. To avoid these, follow the recommended guidelines for storage and reactions, and always check for the efficacy of digestion along with purification of digested products on an agarose gel.

A restriction enzyme or restriction endonuclease is defined as a protein that recognizes a specific, short nucleotide sequence and cuts the DNA only at or near that site, known as restriction site or target sequence. The four most common types of restriction enzymes include: Type I (cleaves at sites remote from a recognition site), Type II (cleaves within or at short specific distances from a recognition site), Type III (cleave at sites a short distance from a recognition site), and Type IV (targets modified DNA- methylated, hydroxymethylated and glucosyl-hydroxymethylated DNA). The most common challenges with restriction digest include- 1. inactivation of the enzyme, 2. incomplete or no digestion, and 3. unexpected cleavage. The enzyme should always be stored at -20C and multiple freeze-thaw cycles should be avoided in order to maintain optimal activity. Always use a control DNA digestion with the enzyme to ensure adequate activity (to avoid interference due to high glycerol in the enzyme). For complete digestion, make sure that the enzyme volume is 1/10th of the total reaction volume, the optimal temperature is constantly maintained throughout the reaction, the total reaction time is appropriately calculated based on the amount of DNA to be digested, appropriate buffers should be used to ensure maximal enzymatic activity, and in case of a double digest, make sure that the two restriction sites are far enough so that the activity of one enzyme cannot interfere with the activity of the other. Star activity (or off-target cleavage) and incomplete cleavage are potential challenges which may occur due to suboptimal enzymatic conditions or inappropriate enzyme storage. To avoid these, follow the recommended guidelines for storage and reactions, and always check for the efficacy of digestion along with purification of digested products on an agarose gel.

Wound healing assay can be challenging due to inconsistencies and variations while making a wound on the confluent cell monolayer, consequently leads to wounds of varying sizes and widths. Moreover, this assay causes damage to the cells that are at the edge of the wound, which can prevent cell migration into the wound site and healing. The best solution is to use the standard wound healing assay kits using either combs or inserts to make a defined wound field or gap and prevent the well-to-well variation in these assays.