Weekly reads: ‘junk DNA’, COVID chaos, CRISPR CasΦ, & postdoc opps, more

Here are our weekly recommended regenerative medicine and other notable science reads including a few things on COVID. It’s been quite an interesting week.

“Junk DNA” is not so junky, role in differentiation

NIH scientists showed how ancient retroviral genes, or “junk DNA”, may play a role in helping stem cells decide to become neurons. This work is from the Nath lab, NIH/NINDS.

You can see a YouTube video above on the work and an artistic rendering of some of what the authors think is going on below. Of course, junk DNA is not really junky at all. Here’s the pub itself in PNAS: Regulation of stem cell function and neuronal differentiation by HERV-K via mTOR pathway.

Retroviral genes Junk DNA NIH

Lower bar for herd immunity to COVID-19?

The Atlantic has a great article on herd immunity here. It provides some surprising insights including that the percent of people in a population who need to have had COVID-19 could be much lower than you think in some regions.


There are a number of factors including that modeling predicts that those infected early in a pandemic may be hyper-sensitive to infection, which means the remaining population 6-12 months later, although not yet immune, may be less susceptible.

Chaos theory and other frameworks come into play.

A new kind of Cas nuclease CasΦ for CRISPR

Check out this interesting piece: CRISPR-CasΦ from huge phages is a hypercompact genome editor. It may be compact enough to have better delivery for CRISPR gene editing.

Reciprocal CRISPR

In case you missed it, I hope you’ll read our new paper on using gene editing to model how specific childhood glioma mutations work. We call this kind of CRISPR by the name “reciprocal gene-editing”. Here’s a post I did with more backstory on the pub and what we think it tells us.

UCSC & CSUMB postdoc stem cell positions

Some great postdoc opportunities for stem cell researchers on the beautiful California coast.

How sound is foundation for cellular therapies for COVID-19?

This Cell Trials piece was published in April, but I wanted to highlight it again as it’s worth a read and I don’t think the cell therapy field has much of any newer data to support the idea of MSCs for COVID-19.

Can you make sperm from stem cells? Risks?

Researchers from UCSD published new work in PNAS about efforts to differentiate sperm from stem cells. Here’s a UCSD piece: Human Sperm Stem Cells Grown in Lab, an Early Step Toward Infertility Treatment.

Here’s the actual PNAS article: Transcriptome profiling reveals signaling conditions dictating human spermatogonia fate in vitro. They didn’t make mature sperm, but got closer and made undifferentiated spermatogonia.

This is more in a long-line of work trying to make gametes from stem cells. I still feel a bit queasy about the idea of using this kind of approach to try to tackle infertility. First, it just seems impossible to know if it’s safe to make human babies this until it’d be too late after you try it in people and something goes wrong. Second, this step also opens the door to more attempts at CRISPR babies.

2 thoughts on “Weekly reads: ‘junk DNA’, COVID chaos, CRISPR CasΦ, & postdoc opps, more”

  1. Could a sperm (or ovum) made from an adult IPSC be independent of the donor’s gender? In any case, this seems like a sort of gametogenesis that might not result in genomically imprinted gametes. Do we know enough about the process of genomic imprinting to say that any IPSC-induced gamete could never contribute to a viable embryo?

    1. Deepa Bhartiya

      There is a difference between a sperm and sperm stem cells. Sperm stem cells have a long way to differentiate, undergo meiosis and further spermiogenesis to become a sperm. Lot more efforts need to go into the filed to treat infertility

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