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Molecular Biology Tissue Fixative




STUMol is a preferred fixative for the recovery of biomolecules in tissue by researchers and molecular pathologists. STUMol effectively fixes tissue without alteration of architecture or distortion of intracellular features. Most importantly, STUMol preserves tissue for recovery of high quality DNA, RNA and proteins in very workable quantity. Nucleic acids recovered from STUMol-fixed tissue can be used in gene expression analyses such as RT-PCR, microarrays and in-situ hybridization, immunohistochemistry and sequencing.

For immunohistochemical staining of tissue epitopes, STUMol is an optimal fixative. Unlike formalin which blocks antigen expression through fixative-induced chemical crosslinks, STUMol is a precipitating fixative which does not form adducts or cross-links. Cross-link bonding does not have to be broken by antigen retrieval methods. The elimination of fixative-induced hindrance to tissue antigens means specific antibodies complex antigens very efficiently. In many cases, antibodies may be used at higher dilution, and visualization of reacted complexes is brilliant and sharp.

For those performing laser capture microdissection, the ultimate success of the procedure, recovery of biomolecules from select cells of interest, is highly dependent upon the efficacy of the tissue fixative used. Formalin-fixed tissues are not a good source of nucleic acids and proteins for study. Formaldehyde is brutal to nucleic acids, and formaldehyde distorts the conformal structure of proteins. STUMol-fixed tissues are an excellent source of nucleic acids, both in quality and quantity, and recovered proteins require no pretreatment for examination.

The understanding of nucleotide sequence in DNA (and RNA) is of utmost importance in formulating new methods of treating cancer (personalized medicine). High throughput sequencers use millions of nucleic acid fragments through an automated process called massive parallel sequencing. What is critical to the value of sequencing is purity of sample input. Formaldehyde in formalin severely alters nucleic acids by adducts and cross-links, which bring about deleterious changes to nucleic acids: nucleotide deletion and substitutions. Additionally, nucleic acid quantity is greatly reduces. Ultimately, formaldehyde-induced nucleotide alterations make it incredibly difficult to discern an actionable mutation from and artifact.

STUMol is methanol-based with added select ingredients to protect tissues during the fixation process. STUMol is superior to ethanol-based fixatives for both DNA and RNA preservation and recovery. In particular, RNA integrity in STUMol-fixed tissue is high, with considerably less RNA content loss than from ethanol-based fixed tissue, and from aldehyde-based (formalin and glyoxal) fixed tissue.

Tissues fixed in STUMol can be safely processed by conventional or microwave processing. The appearance of STUMol-fixed tissue by light microscopy is excellent, similar to that of formalin-fixation, and all routine and special stains can be used with STUMol-fixed tissue.