CRISPR Mouse Deletion ES (embryonic stem) cells

The estimation of DNA methylation level heavily depends on the complete conversion of non-methylated DNA cytosines. It is crucial to ensure complete conversion of non-methylated cytosines in DNA. Therefore, it is important to incorporate controls for bisulfite reactions, as well as to pay attention to the appearance of cytosines in non-CpG sites after sequencing, which is an indicator of incomplete conversion.

The process of RNA extraction from bacteria, in general, involves an RNA-protective, effective lysis of bacterial cell wall (which may pose difficulties). EDTA promotes loss of outer membrane to provide lysozyme with access to peptidoglycan. Another common method for cell wall lysis is mechanical disruption using a homogenizer (applied for gram-positive bacteria and some strains of gram-negative bacteria). Following lysis, it is necessary to disrupt protein-nucleic acid interactions, which can be achieved by adding sodium dodecyl sulfate (SDS). Next step involves using phenol-chloroform-isoamyl alcohol extraction, where RNA can be obtained from the bottom organic phase, the top phase consists of DNA and the interphase contains proteins. Isoamyl alcohol is an inert and optional addition to this mixture and is added as an anti-foaming reagent to reduce the interphase. Following RNA extraction, the samples should be checked for its quality by gel electrophoresis (23S and 16S rRNAs and 5s rRNA and tRNA bands) or UV spectrophotometric or fluorescence methods.

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been greatly used for studies on embryonic development and cell differentiation.iPSCs provide a stable source for either self-renewal or differentiation into suitable cells when cultured in a particular environment. Pluripotent cell culture was originally started by deriving cells from inner cell mass (ICM) from pre-implanted blastocysts, these were called embryonic stem cells. These cells after isolation can be grown on traditional extracellular matrices (like mouse embryonic fibroblasts, MEFs) or feeder-free culture systems. DMEM/F12 has been the most commonly used basal media in the culture of pluripotent cells. These cells are cultured at normal atmospheric oxygen levels, 21%, however, some studies have proposed that 4% oxygen tension may be better for hESC growth. Higher D-glucose concentration (4.2g/l) and osmolarity (320mOsm) that mimics the natural environment of embryonic tissue are optimal for the growth of hESCs. Supplements like N2 and/or B-27, in the presence of growth factors like bFGF, have been shown to increase pluripotency of these cells. bFGF, FGF2 and other ligands of receptor tyrosine kinases like IGF are also required or maintain self-renewal ability of these cells. TGF𝛃1, by its activation of SMAD2/3 signalling, also represses differentiation of iPSCs. Other compounds like ROCK inhibitors reduce blebbing and apoptosis in these cells to maintain their clonogenicity. However, an inhibitor for LIF (leukaemia inhibitory factor, which is one of the pluripotent genes) has an opposing effect. Therefore, it is important to understand the culture conditions and media composition that affect downstream signalling in hESCs or iPSCs that may lead to their differentiation.

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been greatly used for studies on embryonic development and cell differentiation.iPSCs provide a stable source for either self-renewal or differentiation into suitable cells when cultured in a particular environment. Pluripotent cell culture was originally started by deriving cells from inner cell mass (ICM) from pre-implanted blastocysts, these were called embryonic stem cells. These cells after isolation can be grown on traditional extracellular matrices (like mouse embryonic fibroblasts, MEFs) or feeder-free culture systems. DMEM/F12 has been the most commonly used basal media in the culture of pluripotent cells. These cells are cultured at normal atmospheric oxygen levels, 21%, however, some studies have proposed that 4% oxygen tension may be better for hESC growth. Higher D-glucose concentration (4.2g/l) and osmolarity (320mOsm) that mimics the natural environment of embryonic tissue are optimal for the growth of hESCs. Supplements like N2 and/or B-27, in the presence of growth factors like bFGF, have been shown to increase pluripotency of these cells. bFGF, FGF2 and other ligands of receptor tyrosine kinases like IGF are also required or maintain self-renewal ability of these cells. TGF𝛃1, by its activation of SMAD2/3 signalling, also represses differentiation of iPSCs. Other compounds like ROCK inhibitors reduce blebbing and apoptosis in these cells to maintain their clonogenicity. However, an inhibitor for LIF (leukaemia inhibitory factor, which is one of the pluripotent genes) has an opposing effect. Therefore, it is important to understand the culture conditions and media composition that affect downstream signalling in hESCs or iPSCs that may lead to their differentiation.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.

The RNA-guided CRISPR-Cas9 nuclease system has revolutionized the genome editing practices. For the most part, the Cas9-mediated genome editing is performed either via nonhomologous end joining (NHEJ) or homology-directed repair (HDR) in mammalian cells, However, designing of specific sgRNAs and minimizing off-target cleavage mediated mutagenesis are the major challenges in CRISPR-Cas based genome editing. To circumvent these issues, we can take advantages of many available tools and approaches for sgRNA construction and delivery.