Two items relevant to long COVID

One of the tricky issues in studying in long COVID is: how widely do researchers cast their net? Initial reports acknowledged that people who were hospitalized and in intensive care may take a while to get back on their feet. But the number of people who had SARS-CoV-2 infections and were NOT hospitalized, yet experienced lingering symptoms, may be greater. A recent report from the United Kingdom, published in PLOS Medicine, studied more than Read more

All your environmental chemicals belong in the exposome

Emory team wanted to develop a standard low-volume approach that would avoid multiple processing steps, which can lead to loss of material, variable recovery, and the potential for Read more

Signature of success for an HIV vaccine?

Efforts to produce a vaccine against HIV/AIDS have been sustained for more than a decade by a single, modest success: the RV144 clinical trial in Thailand, whose results were reported in 2009. Now Emory, Harvard and Case Western Reserve scientists have identified a gene activity signature that may explain why the vaccine regimen in the RV144 study was protective in some individuals, while other HIV vaccine studies were not successful. The researchers think that this signature, Read more

Ingenious Gene Targeting

Manipulating mouse genes to order, CRISPR or old-school

Just a follow-up to last week’s announcement from the Emory Transgenic Mouse and Gene Targeting core that they are offering CRISPR/Cas9 gene editing for mice. Using CRISPR/Cas9 to produce genetically altered mice is a

Knockout_mice

Gene targeting – the 20th century way

substantial advance over the old way of doing knockouts and other manipulations (which itself won a Nobel Prize in 2007), mainly because it’s faster and easier.

To appreciate the difference, consider that the old way involves introducing DNA into mouse embryonic stem cells, and then selecting for the rare cells that take up and incorporate the DNA in the right way. Then the ES cells have to be injected into a blastocyst, followed by mouse breeding to “go germline.”

With CRISPR/Cas9, it’s possible to inject pieces of RNA that target the desired genetic changes, straight into a one-cell stage mouse embryo. Not every embryo has all the right changes, but the frequency is high enough to inject and screen. As this review explains, it’s possible to introduce mutations into three genes at once and get mice quickly, rather than make each one separately and then breed the mice together, which can take many months.

Also, because of the need for drug selection, the targeting construct in old-school gene targeting has to be a blunt instrument. That can make it hard to make subtle changes to a gene — like introduce point mutations corresponding to natural variations linked with human disease — without taking a sledgehammer to the entire gene locus. CRISPR/Cas9 takes care of that problem.

Despite the advantages of this technology, three things to keep in mind:

*Many genetically altered mice are already available “off the shelf” as part of the International Knockout Mouse/Mouse Phenotyping Consortium.

*Emory’s Mouse Core has been working with the company Ingenious Gene Targeting, and has been out-sourcing some of the tedious aspects of old-school gene targeting in mice to Ingenious, starting last year. Technicians there can generate a dazzling array of conditional knockouts. If you want your favorite gene to flip around and produce a fluorescent protein when you give the mice an antibiotic, but only in some cells — Ingenious can do that. Old school is actually still the way to go for fancy stuff like this.

*Jackson Labs in Maine also works with Emory, offering similar services, and offers a guarantee. Read more

Posted on by Quinn Eastman in Uncategorized Leave a comment