Today's Holy Crap Science Moment:

[theweaselking]

Symbiotic endogeneous retroviruses in viviparous mammals

Short version: the reason most mammals are capable of live birth is that our ancestor *ate* a virus, one much along the lines of HIV. In the process of and after killing it, they developed a hugely more effective immune system, and now they produce this virus selectively to protect their embryos from this violently more powerful immune system.

HOLY CRAP.

Biology is cool.

Comments

[chizzer.livejournal.com]

0_o

Life is odd.

[opaqueplanet.livejournal.com]

endogenous retroviruses: so effing awesome. A symbiotic retrovirus that we've developed a reproductive system around? HELLS of awesome.

(As an aside, HIV is an exogenous retrovirus, and as such, doesn't change the host's DNA like an endgenous retrovirus does.)

[theweaselking.livejournal.com]

It isn't passed to the children via DNA, but that's not the point. The point is that an HIV-equivalent virus is now *required* for mammalian reproduction because some lizardlike protoanimal got infected and then *ate* the fucking thing?

That's awesome.

[opaqueplanet.livejournal.com]

Maybe I was unclear.

Endogenous retroviruses, like this one, DO change the host's DNA. So we do pass them to our kids (in this case, it's why our kids reproduce with the same viral mechanism). This particular virus is like HIV *only* insofar as it suppressed the autoimmune response. While HIV is also a retrovirus, it is a very different kind: and EXogenous one (one that changes the genes of the cells it infects, but not the germline cells, so it's not passed on to children through DNA).

I was simply pointing out that the virus in question and HIV do not share the same classification (endogenous/exogenous) of retroviruses.


However, that was intended just as an aside for those who were interested in or confused by the "much like HIV" part of the post. My main point was just ... agreeing with you on how awesome endogenous retroviruses are. Especially this one.

[theweaselking.livejournal.com]

I know what you meant.

And, at the same time, the virus in question was HIV-like in that it was an immunosuppressant, and caused AIDS-like symptoms.

It's unlike HIV in that HIV doesn't infect the reproductive cells and pass itself on to the child as part of the DNA. That's not the point.

The point is that, at some point, the ancestor of all live-birthing mammals got infected with something much like HIV in effect, and not only did they survive it, but they took it an PUT IT TO WORK.

And THAT is truly awesome.

[opaqueplanet.livejournal.com]

yes.

[jwz.livejournal.com]

HERVs like this are the main macguffin in "Darwin's Radio" and "Darwin's Children" by Greg Bear. I'm halfway through the second one; they're pretty good.

[jagash.livejournal.com]

*chuckles* I love my field of study at times.