Xenotransplantation: time to go deeper

Photo credit: Joe Carrotta

And so it happened. “In a first, surgeons attached a pig kidney to a human, and it worked,” as the New York Times puts it. Data are scarce, however, and all the info we have is from the general media. The kidney came from a GalSafe pig, which is the only one FDA approved so far. But scientists from several companies have already developed pigs much more engineered than that (with three or four porcine genes knocked-out instead of one, and human gene additions). To get an updated picture, we highly recommend this article published in Nature Biotechnology last April.

GM mosquitoes play rock paper scissors

Anti-CRISPR proteins are the rock needed to stop CRISPR-based mosquito-eradicating gene drives, if necessary, and make them safer. In a news feature published last year in Nature, the molecular parasitologist Andrea Crisanti disclosed unpublished data about halting an anti-malaria gene-drive system by adding anti-drive mosquitoes to the mix. “They can completely, 100% block the drive. We can stop the [Anopheles gambiae] population from crashing,” he said. According to the scientist from the Imperial College London, it’s kind of like buying an insurance. Looking ahead to field-testing his sterilization strategy, Crisanti imagined having cages of anti-drive mosquitoes at the ready, just in case things go awry. Well, that work is now published, and anti-drive mosquitoes are a reality. To learn more, see the paper published on June 25 in Nature Communications by Chrysanthi Taxiarchi et al.

Where is the revived mammoth?

I watched Genesis 2.0, which is debuting in Italy almost two years after its release at the Sundance Film Festival. In the meanwhile, Semyon Grigoriyev has died. The Russian paleontologist leading the effort to clone a mammoth was one of the movie’s main characters. He always had little chance of success, and the plan’s odds are now worse than ever.

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Edited shells turn left

snail crispr cover

Most snails live in right-coiled shells, and the general rarity of sinistral gastropods has long attracted comment and wonder, according to the late Stephen Jay Gould. “Aristotle declared them impossible, but d’ Argentville called them uniques, while Geoffroy dubbed them nonpareilles. Since no one has ever developed an even vaguely plausible argument for dextral advantage, the overwhelming predominance of right-handed coiling among gastropods has been a persistent puzzle.” Continue reading

Animal Farm. Fresh CRISPR stories

Wired cover April 2019Edited animals are in the news this week. Wired dedicates its cover story to “A more human livestock industry, brought to you by CRISPR,” focusing on experiments being done at the University of California, Davis. Alison Van Eenennaam is trying to alter sexual traits in cattle by targeting a single gene called SRY. The science is still difficult, however, and US regulations uncertain. Continue reading

Picture of the week

bimaternal pups

Healthy adult bimaternal mouse (born to two mothers) with offspring of her own.
Credit: Leyun Wang

Single-gender worlds will remain a sci-fi fantasy. Gay and lesbian couples won’t become parents this way for the foreseeable future. This kind of manipulation is just too risky for humans. But unisexually reproducing mice are an impressive accomplishment, and CRISPR stands out again as a powerful research tool, opening up brand new possibilities for the study of genomic imprinting. For further details, please see the STAT News article about the Cell Stem Cell paper by Zhi-Kun Li.

Gene drives & the trolley dilemma

malaria kills

The trolley problem is a classic philosophical dilemma, and its variants have been used extensively to test moral intuitions. Scanning the brain of human subjects with functional MRI during task performance has proven useful to understand how emotion and reason interact when we ponder bioethical issues. It would be interesting to adopt those approaches to study the psychological barriers towards controversial innovations such as gene drives. Just imagine you alone are responsible for pressing a button and switching on gene drives in malaria-spreading mosquitoes. Someone is going to die, and you must decide whom to save. Continue reading

CRISPR diving the coral reef

coral-bleachingThey are not super-corals genetically edited to repopulate the reef. However, the Acropora millepora described in PNAS last week are the first baby polyps ever CRISPRed in a lab, by a team involving Stanford University, UT-Austin and the Australian Institute of Marine Science in Townsville. These uncontroversial organisms pave the way for future experiments to reveal the molecular basis of vulnerability to bleaching, the fatal loss of algal symbionts triggered by global warming. Most corals reproduce once or twice a year, ejecting huge quantities of sex cells resembling underwater snowflakes. The time window of these spawning events can be predicted quite accurately, so researchers can sample the reef at the right moment and collect early embryos for genetic manipulation. We discussed the experiment results and future perspectives of gene editing in corals with the paper’s first author Phil Cleves.

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