Planet Care

95: De-extinction via DNA


One of the most powerful tools to fight biological obliteration is CRISPR, (Clustered Regularly Interspaced Short Palindromic Repeats) involving slicing DNA apart then adding and subtracting genes at will.

In 1987, researchers at Osaka University studying the function of Escherichia coli genes first noticed a set of short, repeated DNA sequences, but they did not understand the significance.

Six years later, another microbiologist, Francisco Mojica at the University of Alicante in Spain, noted the sequences in a different single-celled organism, Haloferax mediterranei. The sequences kept appearing in other microbes and in 2002, the unusual DNA structures were given a name: CRISPR.

In 2012, Jennifer Doudna, from UC Berkeley, and Emmanuelle Charpentier, at Umea University, Sweden, showed CRISPR could be hijacked and modified. Essentially, they had turned CRISPR from a bacterial defence mechanism into a DNA-seeking missile strapped to a pair of molecular scissors. For this they were awarded the 2020 Nobel Prize in Chemistry.

Their modified CRISPR system worked extremely well, finding and cutting any gene they chose. The floodgates opened, and CRISPR research, which had long been the domain of molecular microbiologists, skyrocketed. The number of articles referencing CRISPR in preeminent research journal Nature has increased by over 6,000 % between 2012 and 2018.

One scientist who is using CRISPR for a particular de-extinction is Ben Novak, a lead scientist with conservation non-profit Revive & Restore in Sausalito, California. Novak is working to bring back the passenger pigeon, once North America’s most abundant bird. The last passenger pigeon, a female named Martha, died in the Cincinnati Zoo in 1914, rendering the species extinct.

Novak spends most of his time in a facility southwest of Melbourne, Australia, working with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) breeding band-taileds. To completely resurrect the passenger pigeon, Novak and his team are working to create a hybrid pigeon with parts of the CRISPR system embedded within its genes. The hybrids will be bred for several generations until the offspring DNA matches that of the extinct species. The first generation of ‘revived’ pigeons is expected to hatch in 2022.

In 2019, scientists at the North-Eastern Federal University in Yakutsk and the South Korean Sooam Biotech Research Foundation have succeed in extracting liquid blood from heart vessels of a 42,000-year-old Lenskaya breed foal excavated in the Batagai depression. The autopsy showed beautifully preserved internal organs. Scientists already indicated that they were confident of success in extracting cells from this foal to de-extinct its species.

Elsewhere, in a study published in Scientific Reports, a team of scientists from Japan and Russia at Kindai University, in central Japan announced that they have managed to recover cells from the left hind leg of a 28,000-year-old juvenile mammoth that was discovered in the Siberian permafrost in 2011. Cell nuclei from the mammoth were successfully implanted in mouse cells were able to react and that there is biological activity.

In 2019, David Liu, a chemist at the Broad Institute in Cambridge, Massachusetts invented “prime editing” which further improves on the CRISP-Cas-9 solution by offering more targeting flexibility and greater editing precision.

Although CRISPR should prove useful in de-extincting ancient species, perhaps more importantly in its ability to help living species that are in danger of becoming extinct, it is certainly a Planet-protecting solution.

This of course includes plants.

American chestnut trees dominated the East Coast of the U.S. until 1876, when a fungus carried on imported chestnut seeds devastated them, leaving less than 1 % by 1950. To make blight-resistant trees, scientists have inserted a wheat gene into chestnut embryos, enabling them to make an enzyme that detoxifies the fungus. This chestnut tree is likely to become the first genetically modified organism to be released into the wild once it is approved by the Department of Agriculture, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA).

Genomic research on crops, for example, has already yielded plants that grow faster, produce more food, and are more resistant to pests or severe weather. Researchers may find new medicines or discover better ways to engineer organisms for use in manufacturing or energy.

What you can do: Help those organisations such as WWFN and IUCN to save threatened species.

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