Researchers hungry for an adaptable system for the high-sensitivity quantification of biomolecules may have found the answer in... tadpoles?
Considering the sensitivity and versatility of Polymerase Chain Reaction (PCR)-based applications, biologists can perhaps be forgiven for becoming a bit spoiled, and demanding the same ease and level of sensitivity for the detection of non-nucleic acid-based molecules. However, a powerful new tool described in the January issue of Nature Methods promises just such sensitivity for the detection of a versatile range of targets, including proteins and small-molecule compounds.
Meet the 'tadpole': a new breed of DNA-protein hybrid developed by Ian Burbulis, Roger Brent, and their colleagues at the Molecular Sciences Institute (Berkeley, CA). The tadpole 'head' consists of a protein element, such as an antibody, with targeted affinity for a specific molecule, while the 'tail' is a unique DNA tag that enables PCR-based quantification. The two halves are synthesized separately, and then neatly joined via a naturally occurring splicing reaction to generate the ready-to-use tadpole.
After adding the tadpoles to a sample, the amount of tag sequence amplified by PCR reveals the quantity of tadpole-bound target with surprising accuracy. Burbulis et al. began with a tadpole targeted against the vitamin biotin, and found that they could detect as few as 600 molecules with 95% confidence, and that their tadpoles offered a limit of detection 109 lower than ELISA, a commonly used antibody-based diagnostic assay. They achieved equally sensitive detection using different kinds of 'head' molecules to quantify targets such as anthrax toxin, consistently surpassing the limits of ELISA.
In an accompanying News & Views feature, Stanford researcher Garry Nolan assesses the tadpole, and concludes that the simplicity, adaptability, and sensitivity of this approach "make this an appealing system for researchers wanting a standardized, high-throughput, and accurate detection system for... just about anything."
Roger Brent (The Molecular Sciences Institute, Berkeley, CA, USA)
Tel: +1 510 647 0695
Garry Nolan (Stanford University, Stanford, CA)
Tel: +1 650 725 7002
For media inquiries relating to editorial content/policy for Nature Methods, please contact the journal directly:
Michael Eisenstein, Nature Methods (New York)
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