A 62176 hydrochloride

Reverse transcription technology uses RNA as a template to synthesize DNA. RT-PCR is simple, specific and sensitive, and can be used to detect gene expression levels and expression differences in cells; detect RNA virus content; clone cDNA sequences of specific genes.

By lysing cells, releasing RNA, and removing impurities such as proteins and DNA, high-purity RNA products are finally obtained. The commonly used traditional method is the guanidine isothiocyanate/phenol/chloroform method (Trizol), which is suitable for a variety of animal materials including animal tissues, microorganisms, cultured cells, etc., and most plant materials.

CRISPR-Cas9 HDR knock-in uses a guide RNA to direct Cas9 to a genomic target adjacent to a PAM, where Cas9 creates a double-strand break; if a donor DNA template with homology to the cut region is present, cellular HDR can copy the donor sequence into the genome, producing a precise substitution, tag, reporter, or insertion rather than an indel. The readout is the fraction of alleles or cells carrying the intended donor-derived edit, measured by junction PCR, restriction-fragment analysis, Sanger sequencing, amplicon deep sequencing, flow cytometry for reporter knock-in, or clone genotyping; NHEJ indels and partial or non-HDR insertions are measured in parallel because they compete with or confound precise HDR outcomes.

Real-time quantitative PCR (qPCR) quantifies an amplifiable nucleic-acid target by monitoring fluorescence during PCR cycling rather than measuring product only after amplification. The increase in fluorescence tracks accumulation of PCR product, and the quantification cycle (Cq; historically also Ct/CP) is related to the initial amount of target: samples containing more starting target generally reach the defined fluorescence threshold in fewer cycles.

The bacterial reverse mutation assay detects point mutations that restore amino-acid prototrophy in auxotrophic Salmonella typhimurium or Escherichia coli tester strains; after exposure to a test article, mutagenic activity is read out as an increased number of revertant colonies on minimal agar compared with the vehicle control. The assay uses tester strains with different mutation targets so that base-substitution and frameshift mutagens can be detected, and testing is performed with and without exogenous mammalian metabolic activation because some chemicals require biotransformation to become mutagenic.