Pages Menu
Categories Menu
FORUM

FORUM

Welcome to the Objective Europa forum for general debate and discussions in areas related to a crewed mission to Jovian moon Europa. Suggestions and ideas in the forum will not be filed as part of the research in phase-I.

  • If you have not registered for the forum, please do so (see login link below).
  • Please browse through the topics to find a relevant space for your input.
  • Posting image concepts, links to relevant Europa topics and video are encouraged.
  • We encourage you or others to gather your concepts and ideas from this forum in reports for phase-I.
  • Contact via forum-email if you have suggestions for additional topics or categories.
  • Flaming, trolling and libel activity are cause for immediate post deletion and login denial.

Welcome Guest 

Show/Hide Header

Welcome Guest, posting in this forum requires registration.

Pages: 1 2
Author Topic: Testing for Life


Rex
Europa Dreamer
Posts: 17
Re: Testing for Life
on: April 2, 2014, 22:04

Quote from Bryan on April 2, 2014, 18:04[/b
Sorry for the deluge of questions. I'm a grad student right now, so asking a ton of questions is pretty much my job. 🙂

Absolutely no problem, questions and debate are very welcome! I see you are studing biology: tell me more, which university? Where are you from? (you can e-mail me at the contact address at the bottom of the paper if you do not wish to disclose this information in the forum)

PS: answers to your questions are on the previous page of this thread!



Bryan
Europa Astronaut
Posts: 98
Re: Testing for Life
on: April 3, 2014, 03:46

I am currently at the University of Memphis, but I am transferring to Rensselaer Polytechnic in the Fall to start their program. I'm wanting to study microbial ecology/ environmental microbiology. Right now I'm doing molecular cloning for a parasitology project.

I can see how disulfide (or other) bonds would limit the bases, but some bases are already highly conserved, so I don't see that to be the problem. Besides aiding in supercoiling, it might also be a component of gene regulation, aid in stability against degradation, or even part of their replication machinery.

On the off chance that the backbone is neutral (allowing for folding and conformational changes, yet, but conceivable), I would think the nanopore system would work, it would just need more voltage to transverse, similar to proteins.



Rex
Europa Dreamer
Posts: 17
Re: Testing for Life
on: April 3, 2014, 17:49

It looks like a nice path for your studies, my background is also basically microbial ecology and environmental microbiology! 🙂
I’m curious: how did you came to the hypothesis of covalent bonds for packaging? Is it your idea or you have a reference to indicate? I’d be interested to get deeper into this topic: it’s intriguing!

Another factor that should be taken in consideration with this hypothesis is the energy that is necessary to form these covalent bonds: how many of them would be necessary to supercoil a DNA analogue? Remember that gene regulation would require these bonds to be formed and dissociate continuously, which at the end may result in a pretty high energy-burden for the cell. Eukarya and archaea regulate the interaction between DNA and histones by chemical modifications of the latter in a very energy-parsimonious manner, i.e. usually by eliminating the positive charge of selected N-terminal aminoacids (e.g., arginine or lysine methylation/acetylation) or by adding a negative charge to a neutral one through phosphorylation.
If somebody out there has still fresh knowledges of thermodynamics & physical chemistry it would be interesting to compare the two cases! I’m unfortunately quite rusty at that... 🙁



Bryan
Europa Astronaut
Posts: 98
Re: Testing for Life
on: April 3, 2014, 18:45

After I read your paper, I tried to think of ways that the molecule wouldn't fit through the pore. That was something that I just threw out there as a possibility. I don't remember reading it anywhere else.

What if the covalent bonds were semi-permanant: only dissociating for replication? They could form hairpin-like structures in non-coding regions that could serve both as protection against nucleases as well as attachment points for histone-like packaging molecules.

I just looked up bond-dissociation energy, and the disulfide bond is pretty weak. It may be the lowest energy form of packaging the cells evolved.



Bryan
Europa Astronaut
Posts: 98
Re: Testing for Life
on: April 4, 2014, 02:30

I did find this paper, showing some proteins are covalently bonded to nucleic acids.

http://nar.oxfordjournals.org/content/26/21/4791.full



Rex
Europa Dreamer
Posts: 17
Re: Testing for Life
on: April 4, 2014, 10:16

Interesting, I've dug a little deeper and found out that these DNA–protein covalent complexes (DPCCs) are apparently principally involved as transient intermediates in a variety of transactions such as DNA repair, conformational changes through topoisomerases, etc. (see references cited herein http://nar.oxfordjournals.org/content/41/9/e104.abstract).



Bryan
Europa Astronaut
Posts: 98
Re: Testing for Life
on: April 4, 2014, 19:10

Are they necessarily transient? Would they stay if we someone inactivated the next enzyme in the process?



Rex
Europa Dreamer
Posts: 17
Re: Testing for Life
on: April 4, 2014, 20:27

I think so, according to the paper some anti-cancer drugs are based on that principle: by inhibiting these enzymes they prevent coiling and uncoiling of DNA and thus cell replication.

Pages: 1 2
Mingle Forum by cartpauj | ElegantPress by Theme4Press and SOFTthemes | Sponsored by Sasina Therapy
Version: 1.0.34 ; Page loaded in: 0.045 seconds.