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Tuesday, July 4th, 2017 07:50 am

When i was listening to the biology & genetic lectures a few years ago, i was astounded by new realizations. The key has to do with how DNA is NOT a blueprint, a description of the final structure. It's much more like computer code, with all the cruft that developers often leave in a great big system, code that used to do something important, but the output is no longer needed. Somehow activate that code path, and the code can still execute. On the other hand, since the system has evolved away from that need, it the code does execute, it's not necessarily going to behave as it did originally.

DNA doesn't execute in a vacuum: chemical and physical signals affect what segments of the DNA will be activated. The embryonic environment has a huge impact on the gene expression in a developing organism -- i can't find a recent article i read about how poverty-stress of a mother can be expressed in the cognitive pathway development of the child, thus providing a physiological basis for poverty changing the way one literally thinks.

(In Butler's Wild Seed, one of the characters could "examine" the DNA of a creature and then express the creature. My awareness of how gene expression works triggered a momentary collapse of my suspension of disbelief.)

So, i pondered, what if an organism was exposed to primordial compounds, compounds that don't exist in the oxygen rich environment of today? What parts of the "junk" DNA might be activated? What might happen next? (Could an alternative being be in the DNA that could be expressed with the right primordial signals?) Keyword for more research: epigenetics.

" It’s for sure that there are many biosynthetic-looking gene clusters found in these species that don’t seem to be turned on most of the time, which makes one think that under the right conditions you could perhaps elicit some “break glass in case of emergency” structures that might be well worth seeing."

Derek Lowe, July 3, 2017

Why, yes, exactly.

[The group] ran all sorts of stress experiments on the organisms to see if any of these caused some activity. As it turns out, exposure to etoposide and to avermectin, both quite toxic to the organisms, caused some of these biosynthetic pathways to turn on, and several new compounds emerged, including one with antifungal activity and some that appear to be cysteine protease inhibitors.

Hint: Wikipedia relates that "Cysteine proteases... are enzymes that degrade proteins."

Organic chemistry and genetics are so incredibly amazing to me. I envy nascent scientists -- so many of these discoveries have been since i was in school. To be entering the fields with this landscape as a foundation....
Tuesday, July 4th, 2017 01:23 pm (UTC)
That's a great metaphor-- thanks!
Tuesday, July 4th, 2017 05:16 pm (UTC)
One of the common tests for a chemical compound's mutagenicity is to take bacteria that can't metabolise lactose, plate them on a medium that only contains lactose, and dose them with the chemical. The number of bacterial plaques that live show a linear relationship with the chemical's ability to screw up DNA enough to get bacteria to produce lactases that allow them to eat the only local food source.
Tuesday, July 4th, 2017 08:51 pm (UTC)
Cool. Epigenetics fascinating. Definitely there are pathways that only get activated with certain triggers.
Wednesday, July 5th, 2017 01:46 am (UTC)
Geneticists in various areas have been learning by leaps and bounds--it's amazing. Planetary science and neuroscience have been growing like crazy too. I'm amazed every time I listen to Science Friday.
Saw at work that someone had requested a book titled "Epigenetics" from 2011. I thought, "Oh, no, that's going to be way behind what we know now..."
Tuesday, August 15th, 2017 01:28 am (UTC)
We don't do that because we have a huge number of interlibrary loan requests coming in. They could ask a librarian in person, over the phone, or by email for something more recent. I'm sure my colleague who buys science books has bought at least a few. Some people are looking for older books that are referenced or recommended in oops they are reading, or by people they have heard.