October 20, 2018

CRISPR or the truly white button mushroom


White button mushrooms are in every grocery store around the world. As inexpensive as they may be, they have a flaw: they bruise easily, which makes them less attractive. In 2015, a Penn State University researcher, Yinong Yang, turned to the U.S. Department of Agriculture for approval to market an altered strain of the species. The researcher had neutralized a few base pairs of DNA from the genome of the fungus, the pairs producing the enzyme responsible for browning.
The US Department ruled that its authorization was not required, the DNA of a foreign organism not being involved in the procedure. Thus, the produce is not "transgenic" as other GMOs may be and does not represent an environmental risk according to its understanding.
While seemingly incidental, the D.O.A. decision is a milestone in genetic engineering. Arguably, the white button is by far the most consumed mushroom, but the achievement itself is one of a long list of advances since a fortuitous observation made thirty years ago: bacteria defend themselves from viruses by targeting and copying a particular area of their genome labelled CRISPR (for Clustered Regularly Interspaced Short Palindrome Repeats).
In 2008, Philippe Barrangou and his team, working for the food bio-technology corporation Danisco, brought to light the central role of a special protein: protein cas9. It targets, cuts, copies a strand of a viral phage's genome in a bacteria genome, allowing the latter to recognize and destroy the bacteriophage.
In fact, the protein operates like a "molecular scissor" making it possible to edit all genomes, not only that of a bacteria. The procedure, akin to word processing, aims to correct a «letter» in a living organism`s genome which consists of millions of combinations of the four letters A, C, G, T (for adenine, cytosine, guanine, thymine).
While a team of researchers is currently trying to revive the ghost of the woolly mammoth, hopefully others will be trying to improve the ability of mushrooms to degrade plastics.
Visiting Montréal’s Université du Québec in October 2018, professor Barrangou gave us an overview of the innumerable applications. that stretch the imagination. CRISPR cas9 should help in feeding World population, curtailing pollution, and curing previously incurable diseases.
Will we come to master evolution that used to proceed very slowly before human intervention? This story exacerbates visceral questions in need of reassuring answers: shouldn’t we fear accidents, even malevolence when science is so far ahead of common knowledge? Up to now, no international convention governs the use of CRISPR techniques and applications are rapidly expanding in all directions.
Heralded as one of the ten emerging technologies of 2018 in December edition of Scientific American, the procedure appears more effective in cutting out a defective gene than at swapping in a healthy one. Furthermore, some researchers noticed unwanted DNA alterations on other cells.
In any case, against the backdrop of patent disputes, there is a good chance that you will find impeccably white button mushrooms in a grocery store near you.

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