About chromosomal mayhem in edited embryos

Luigi Naldini, SR-Tiget

CRISPeR Frenzy asked Luigi Naldini of the San Raffaele Telethon Institute for Gene Therapy in Milan for comment on three studies published in June on the preprint server bioRxiv. The experiments were carried out independently by the groups of Kathy Niakan of the Francis Crick Institute in London, Dieter Egli of Columbia University in New York City, and Shoukhrat Mitalipov of Oregon Health & Science University in Portland. These findings heighten safety concerns about heritable genome editing (see the news item by Heidi Ledford in Nature). Below you can read Naldini’s thoughts.

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Flowering with CRISPR

Multiplexed heritable gene editing using RNA viruses and mobile single guide RNAs

FT (Flowering Locus T) is a small protein that helps plants know when to flower. Now it also allows geneticists to create heritable gene edits in the shoot apical meristem. The trick is a guide RNA augmented with an FT sequence that promotes cell-to-cell mobility. The result is a new approach to gain access to the germline.

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The fastest CRISPR has a photoswitch

Very fast CRISPR activated by light [Credit: Ella Marushchenko]

Genome editing + optogenetics = very fast CRISPR (vfCRISPR). Two revolutionary techniques meet in the paper by Yang Liu and colleagues just published in Science. The Johns Hopkins University team developed a caged RNA strategy that allows Cas9 to bind DNA but needs light at wavelengths that are not phototoxic to activate cleavage. The cut is immediate upon light exposure, offering scientists a way to study DNA repair from its start. The process is so precise that one allele of a gene can be edited at a time, allowing the generation of heterozygous mutations for studying complex genetic traits. See also the perspective by Darpan Medhi and Maria Jasin in Science.

CRISPR crops in the news

Credit Pairwise Plants

European scientists must wait for the EC to carry out targeted consultations with Member States and EU-level stakeholders. Then the Commission study on new genomic techniques will be delivered by 30 April 2021. In the meantime, the United States has decided to relax the rules for biotech crops.

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All-male mosquitoes to beat malaria

Anopheles gambiae (credit Alekos Simoni)

The idea is bold and seems to have worked fine. By using a DNA cutting enzyme to disrupt the X chromosome, researchers succeeded in distorting the sex ratio of offsprings, eventually leading to the all-male populations collapse. Andrea’s Crisanti and colleagues at the Imperial College London did it to caged Anopheles gambiae mosquitoes in their quest for a genetic strategy to beat malaria. Please see their paper in Nature Biotechnology and the Imperial College press release.

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CRISPR milestone: FDA approves first diagnostic test

May 7th 2020 will be remembered as a good day for CRISPR. Yesterday the first CRISPR/Cas-based test received Emergency Use Authorization from the U.S. Food and Drug Administration. The Sherlock SARS-CoV2 kit works by programming a CRISPR enzyme to detect the coronavirus genetic signature, providing results in about one hour. Quickly and cheaply indeed, as the materials for one test cost about $6.

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