siRNA / miRNA gene silencing Human HeLa EPAS-1

Bacterial culture is a process of letting bacteria multiply in a controlled fashion (temperature, humidity, oxygen content or shaking), in a predetermined culture medium (antibiotic resistance to obtain homogenous clones). It is an important step, especially during cloning, as a single cell can be grown homogeneously (on semi-solid or in liquid conditions) to obtain colonies. As mentioned, bacteria can be cultured in broth cultures (Luria broth or LB) or Petri dishes (Agar plates). A specific antibiotic can be added to the broth or agar plates in order to grow bacteria which have the gene insert conferring its resistance to that antibiotic. Following points are necessary to consider for optimal growth conditions: 1. In general, most bacteria grow well at 37C, but there are some strains which require growth temperatures between 25-30C. 2. It is ideal in broth cultures to fill the flask to ⅓ or less of the total flask volume for optimal aerobic growth. 3. Shaking speeds between 140-180 rpm are appropriate to ensure aeration and that the cells are surrounded by fresh media, and do not settle.

Bacterial culture is a process of letting bacteria multiply in a controlled fashion (temperature, humidity, oxygen content or shaking), in a predetermined culture medium (antibiotic resistance to obtain homogenous clones). It is an important step, especially during cloning, as a single cell can be grown homogeneously (on semi-solid or in liquid conditions) to obtain colonies. As mentioned, bacteria can be cultured in broth cultures (Luria broth or LB) or Petri dishes (Agar plates). A specific antibiotic can be added to the broth or agar plates in order to grow bacteria which have the gene insert conferring its resistance to that antibiotic. Following points are necessary to consider for optimal growth conditions: 1. In general, most bacteria grow well at 37C, but there are some strains which require growth temperatures between 25-30C. 2. It is ideal in broth cultures to fill the flask to ⅓ or less of the total flask volume for optimal aerobic growth. 3. Shaking speeds between 140-180 rpm are appropriate to ensure aeration and that the cells are surrounded by fresh media, and do not settle.

Generally isolating RNA from Gram-negative bacteria is easy, however keeping your working environment clean and RNase free (use RNase inhibitor) is essential. Some common points to keep in mind: a) Use fresh samples for isolation or store them by freezing in RNA stabilizing buffer until use. b) Choose the bacterial input amounts carefully, to ensure buffer volumes are adequate and not to overload the columns.

ROS has a very short half-lives in biological environment as they are influenced by exposure to ambient oxygen. As it is highly reactive and hard to measure care should be taken to ensure the stability of the sample during isolation, preparation, storage, and analysis.

Isolating RNA from tissues and paraffin-embedded tissue samples can be challenging due to cross-linking of biomolecules and fragmented nucleic acids. The best solution is to slice the tissues into smaller pieces and make a homogenate solution (using tissue homogenizer or grinding liquid nitrogen frozen samples) in presence of RNAse inhibitors. The homogenization process should be carried out on dry ice to maintain the integrity of RNA.

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.

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.