분자유전학실험실 (단국대학교 분자생물학과)



 이성욱 ( 2012-10-16 22:13:33 , Hit : 2531
 Early-Earth cells modeled to show how first life forms might have packaged RNA

October 14, 2012

Enlarge Shown are RNA strands (blue) and RNA enzymes (red) coming together within droplets of dextran. Scientists at Penn State have shown that this compartmentalization helps to catalyze chemical reactions. Credit: C. A. Strulson, Penn State University (Phys.org)—Researchers at Penn State University have developed a chemical model that mimics a possible step in the formation of cellular life on Earth four-billion years ago. Using large "macromolecules" called polymers, the scientists created primitive cell-like structures that they infused with RNA—the genetic coding material that is thought to precede the appearance of DNA on Earth—and demonstrated how the molecules would react chemically under conditions that might have been present on the early Earth. The journal Nature Chemistry will post the research as an Advance Online Publication on 14 October 2012. google_protectAndRun("render_ads.js::google_render_ad", google_handleError, google_render_ad);Ads by GoogleDNASTAR RNA-Seq Software - RNA-Seq Alignment & Analysis. Try a fully functional free trial! - www.dnastar.com In modern biology, all life, with the exception of some viruses, uses DNA as its genetic storage mechanism. According to the "RNA-world" hypothesis, RNA appeared on Earth first, serving as both the genetic-storage material and the functional molecules for catalyzing chemical reactions, then DNA and proteins evolved much later. Unlike DNA, RNA can adopt many different molecular conformations and so it is functionally interactive on the molecular level. In the soon-to-be-published research paper, two professors of chemistry, Christine Keating and Philip Bevilacqua, and two graduate students, Christopher Strulson and Rosalynn Molden, probe one of the nagging mysteries of the RNA-world hypothesis. "A missing piece of the RNA-world puzzle is compartmentalization," Bevilacqua said. "It's not enough to have the necessary molecules that make up RNA floating around; they need to be compartmentalized and they need to stay together without diffusing away. This packaging needs to happen in a small-enough space—something analogous to a modern cell—because a simple fact of chemistry is that molecules need to find each other for a chemical reaction to occur." To test how early cell-like structures could have formed and acted to compartmentalize RNA molecules even in the absence of lipid-like molecules that make up modern cellular membranes, Strulson and Molden generated simple, non-living model "cells" in the laboratory. "Our team prepared compartments using solutions of two polymers called polyethylene glycol (PEG) and dextran," Keating explained. "These solutions form distinct polymer-rich aqueous compartments, into which molecules like RNA can become locally concentrated." google_protectAndRun("render_ads.js::google_render_ad", google_handleError, google_render_ad);Ads by GooglePEG Antibody - NEW - Five Monoclonal Anti-PEG Antibodies $650 - $700 per milligram - www.lifediagnostics.com The team members found that, once the RNA was packed into the dextran-rich compartments, the molecules were able to associate physically, resulting in chemical reactions. "Interestingly, the more densely the RNA was packed, the more quickly the reactions occurred," Bevilacqua explained. "We noted an increase in the rate of chemical reactions of up to about 70-fold. Most importantly, we showed that for RNA to 'do something'—to react chemically—it has to be compartmentalized tightly into something like a cell. Our experiments with aqueous two-phase systems (ATPS) have shown that some compartmentalization mechanism may have provided catalysis in an early-Earth environment." Keating added that, although the team members do not suggest that PEG and dextran were the specific polymers present on the early Earth, they provide a clue to a plausible route to compartmentalization—phase separation. "Phase separation occurs when different types of polymers are present in solution at relatively high concentrations. Instead of mixing, the sample separates to form two distinct liquids, similar to how oil and water separate." Keating explained. "The aqueous-phase compartments we manufactured using dextran and PEG can drive biochemical reactions by increasing local reactant concentrations. So, it's possible that some other sorts of polymers might have been the molecules that drove compartmentalization on the early Earth." Strulson added that, "In addition to the RNA-world hypothesis, these results may be relevant to RNA localization and function in non-membrane compartments in modern biology." The team members also found that the longer the string of RNA, the more densely it would be packed into the dextran compartment of the ATPS, while the shorter strings tended to be left out. "We hypothesize that this research result might indicate some kind of primitive sorting method," Bevilacqua said. "As RNA gets shorter, it tends to have less enzyme activity. So, in an early-Earth system similar to our dextran-PEG model system, the full-length, functional RNA would have been sorted and concentrated into one phase, while the shorter RNA that is not only less functional, but also threatens to inhibit important chemical reactions, would not have been included." The scientists hope to continue their investigations by testing their model-cell method with other polymers. Keating added, "We are interested in looking at compartmentalization in polymer systems that are more closely related to those that may have been present on the early Earth, and also those that may be present in contemporary biological cells, where RNA compartmentalization remains important for a wide range of cellular processes." Journal reference: Nature Chemistry Provided by Pennsylvania State University

Read more at: http://phys.org/news/2012-10-early-earth-cells-life-packaged-rna.html#jCp







687   Biopharma startup raises $51M for therapeutic to treat bleeding complications from angioplasty  이성욱 2012/12/22 2486
686   술 퍼먹게 하는 유전자 있다  이성욱 2012/12/07 2835
685   Glybera Gains Official EMA Nod as First Gene Therapy  이성욱 2012/11/06 2638
684   Genomics: The single life  이성욱 2012/11/06 2088
683   CU-Boulder researchers uncover new target for cancer research  이성욱 2012/11/06 2706
682   유럽 첫 유전자 치료제 승인 지단백 리파제 결핍약 '글리베라' 허가  이성욱 2012/11/06 3923
681   Whitehead scientists identify major flaw in standard approach to global gene expression analysis  이성욱 2012/10/29 2200
680   Nobel work boosts drug development  이성욱 2012/10/23 2527
679   유도만능줄기세포, 진짜 만능일까?  이성욱 2012/10/17 2667
  Early-Earth cells modeled to show how first life forms might have packaged RNA  이성욱 2012/10/16 2531
677   Smallest and fastest-known RNA switches provide new drug targets  이성욱 2012/10/11 2449
676   The Nobel Prize in Physiology or Medicine 2012  이성욱 2012/10/09 2537
675   日 교토대, 쥐 유도만능줄기세포로 난자 만들어  이성욱 2012/10/06 3095
674   “몸매는 날씬해야” 강박관념도 유전자 탓  이성욱 2012/10/04 2636
673   유전자 요법의 후각기능 회복  이성욱 2012/09/12 3085
672   인간 게놈 백과사전 완성: 게놈은 유전자의 단순한 집합체가 아니다  이성욱 2012/09/10 2716
671   자궁경부 암 발생에서 HPV E7의 역할  이성욱 2012/09/10 3644
670   Scientists Design Molecule That Reverses Some Fragile X Syndrome Defects  이성욱 2012/09/07 2528
669   잠 못자는 당신, 알츠하이머병 초기증상?  이성욱 2012/09/07 3618
668   게놈 99% 정크 DNA ‘스위치 역할’  이성욱 2012/09/06 2668

[이전 10개] [1]..[21][22][23][24][25][26][27][28][29] 30 ..[64] [다음 10개]
 

Copyright 1999-2021 Zeroboard / skin by ROBIN