N-Heptanoyl-L-homoserine lactone

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.

Gram staining of tissue sections is a histochemical technique used to differentiate Gram-positive and Gram-negative bacteria within histological specimens based on differences in bacterial cell wall structure and dye retention, adapted from classical bacteriological Gram staining into tissue-compatible “histological Gram stain” variants. In tissue applications, modifications of the Brown-Hopps and Brown-Brenn methods are commonly used to improve differentiation of microorganisms embedded within host connective tissue and to reduce overstaining or loss of Gram-negative signal, which are known limitations of earlier approaches. The principle relies on crystal violet-iodine complex retention in Gram-positive organisms and subsequent decolorization and counterstaining steps that allow contrast visualization of Gram-negative organisms against tissue background.

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.