Immunohistochemistry Anti-mouse IgG

miRNA is the inherent gene silencing machinery which can have more than one mRNA target, whereas siRNA can be designed to target a particular mRNA target. By design, both siRNA and miRNA are 20-25 nucleotides in length. The target sequence for siRNAs is usually located within the open reading frame, between 50 and 100 nucleotides downstream of the start codon. There are two ways in which cells can be transfected with desired RNAi: 1. Direct transfection (with calcium phosphate co-precipitation or cationic lipid mediated transfection using lipofectamine or oligofectamine), and 2. Making RNAi lentiviral constructs (followed by transformation and transduction). Lentiviral constructs are time consuming, but provide a more permanent expression of RNAi in the cells, and consistent gene silencing. Direct transfection of oligonucleotides provides temporary genetic suppression. Traditional methods like calcium phosphate co-precipitation have challenges like low efficiency, poor reproducibility and cell toxicity. Whereas, cationic lipid-based transfection reagents are able to overcome these challenges, along with applicability to a large variety of eukaryotic cell lines. When using oligos, the ideal concentration lies between 10-50nM for effective transfection.

The biggest problem in isolating RNA from gram-positive bacteria is the disruption of the cell wall. A lot of protocols employ enzymatic digestion (pretreatment) which may affect gene expression patterns of certain genes. Therefore physical disruption using beads can be a best alternative.

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.

Get tips on using Trichloroacetic acid to perform Protein isolation Bacteria - Bacillus anthracis

Get tips on using LB Broth to perform Bacterial cell culture media Bacillus anthracis

Get tips on using RNeasy Mini Kit to perform RNA isolation / purification Bacteria - Gram positive Bacillus anthracis

Protein isolation is a technique that involves isolation and/ or purification of protein from cells or tissues via chromatography or electrophoresis. The major challenges in protein isolation include: 1. The concentration of proteins in cells is variable and tends to be small for some intracellular proteins. Unlike nucleic acids, proteins cannot be amplified. 2. Proteins are more unstable than nucleic acids. They are easily denatured under suboptimal temperature, pH or salt concentrations. 3. Finally, no generalized technique/protocol can be applied for protein isolation. Proteins may have different electrostatic (number of positively or negatively charged amino acids) or hydrophobic properties. Therefore, protein purification requires multiple steps depending on their charge (a negatively charged resin/column for positively charged proteins and vice-versa), dissolution (using detergents) and unlike in the case of DNA and RNA, instead of using salts, proteins should be isolated by isoelectric precipitation.

Get tips on using AllPrep DNA/RNA Mini Kit to perform RNA isolation / purification Bacteria - Gram positive Bacillus anthracis

Get tips on using RNeasy Lipid Tissue Mini Kit to perform RNA isolation / purification Bacteria - Gram positive Bacillus anthracis

Get tips on using Difco™ Brain Heart Infusion Agar, BD to perform Bacterial cell culture media Bacillus anthracis