How does a Coronavirus Test Work?

The most widely used test uses polymerase chain reaction or PCR, a technique invented in the 1980s. Central to PCR is its ability to “amplify” DNA — multiply genetic material into large enough quantities to analyse. In the case of the coronavirus, the virus’ RNA first needs to be converted to DNA using an enzyme called reversetranscriptase before putting samples into a PCR machine. Samples collected in throat and nasal swabs are mixed with reagents, which are particles that bind to the virus’s genetic material to ensure no other type of DNA in the sample is amplified. Next, the sample is placed in the PCR machine, which uses cycles of heating and cooling to help the reagents amplify the target DNA into millions of copies. A fluorescent dye is added — the dye glows if the result is positive.

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Mutant enzyme could vastly improve recycling of plastic bottles

Recycling isn’t as guilt-free as it seems. Only about 30% of the plastic that goes into soda bottles gets turned into new plastic, and it often ends up as a lower strength version. Now, researchers report they’ve engineered an enzyme that can convert 90% of that same plastic back to its pristine starting materials. Work is underway to scale up the technology and open a demonstration plant next year.

“This is a huge step forward,” says John McGeehan, who directs the center for enzyme innovation at the University of Portsmouth and who was not involved with the work.

Polyethylene terephthalate (PET) is one of the world’s most commonly used plastics, with some 70 million tons produced annually. PET bottles are already recycled in many places. But the current approach has problems. For starters, recycling companies typically end up with a broad mix of different colors of the plastic. They then use high temperatures to melt those down, producing a gray or black plastic starting material that few companies want to use to package their products.

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