Different animal tissues require flexible adjustments to the Trizol RNA extraction method.

Differences in animal tissues affect RNA extraction

Even among animal tissues, liver, fat, muscle, spleen, cartilage, etc. differ greatly in water content, fiber content, and fat content. Although Trizol is a universal lysis reagent, in practice, if the same procedure is used for all tissues, incomplete lysis, low yield, or unsatisfactory purity may occur. Understanding tissue characteristics and making appropriate adjustments is key to improving extraction results.

Adipose tissue: reduce lipid interference first

Adipose tissue has a high lipid content. After directly adding Trizol and homogenizing, the system easily becomes viscous, and during centrifugation lipids may float on the upper layer, affecting phase separation. A common approach is to remove obvious fascia and blood vessels as much as possible during sampling, and optionally perform initial lysis with a small amount of precooled Trizol first, remove the upper lipid droplets, then add the remaining reagent to continue homogenization. The centrifugation time can be appropriately extended to help the aqueous phase and organic phase separate more clearly.

Muscle and fibrous tissue: thorough grinding is more important

Tissues such as cardiac muscle and skeletal muscle contain more fibers, and it is difficult to achieve complete lysis by pipetting alone. It is recommended to use a tissue homogenizer or grinding beads, combined with liquid nitrogen to grind the tissue into a fine powder before adding Trizol. If grinding is insufficient, residual tissue pieces will not only reduce RNA yield but may also introduce DNA or protein contamination. After homogenization, an additional short centrifugation can be added to remove insoluble debris.

Difficult-to-lyse tissues such as cartilage and skin

Tissues such as cartilage and skin have a dense extracellular matrix, making lysis more difficult. Precooling with liquid nitrogen and grinding are common methods, and low-temperature cryogenic grinding equipment can also be used. For cartilage, after grinding, it can first be pre-wetted with a small amount of Trizol, then subjected to formal lysis. If the sample is still turbid, the centrifugation speed can be increased or the centrifugation time extended, and low-temperature conditions can be used when necessary to help improve the clarity of the aqueous phase.

General principles for adjusting the strategy

Regardless of which animal tissue is being processed, three points need attention: first, the sample amount should be moderate to avoid exceeding the lysis capacity; second, grinding should be thorough to reduce residual tissue particles; third, centrifugation temperature and time should be fine-tuned according to tissue type. The optimized RNA is more suitable for subsequent quantitative PCR or transcriptome analysis. Each time the tissue type is changed, a small-scale preliminary experiment can be performed first to observe phase separation and aqueous phase transparency, and then determine the formal protocol.