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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Dear RASMB,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>First I have to thank all those who curate this list server as over the last 10 years as a manager of the lab I run, it has and continues to prove a hugely valuable resource for me and the people I serve.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My question today has to do with the analysis of DNA and it stems from a user interest in performing an AUC equilibrium experiment in the presence of CsCl. My experience to date has been with nanomaterials and proteins so DNA is a new material for me, however I am under the impression that running AUC samples in presence of CsCl is problematical because of the gradient CsCl itself will generate. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The estimated mass of the species of interest is in the range of 10 mega Daltons; this is also a size regime that is new to me.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The objective of the experiment is to characterize nucleic acids extracted from cells which will have a label increasing the mass of the nucleic acid depending on the number of times it has been replicated.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Two questions:<o:p></o:p></p><p class=MsoNormal>Is CsCl necessary to determine the size distribution of molecular species >10MDa?<o:p></o:p></p><p class=MsoNormal>Can a CsCl experiment be performed using equilibrium measurements?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you for considering my question.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Best regards,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>John Sumida<o:p></o:p></p><p class=MsoNormal>Molecular Analysis Facility<o:p></o:p></p><p class=MsoNormal>University of Washington<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:#333333;background:white'>In many spheres of human endeavor, from science to business to education to economic policy, good decisions depend on good measurement.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:#333333;background:white'>Ben Bernanke</span><span style='font-size:10.5pt;font-family:"Helvetica",sans-serif;color:#333333'><br><br></span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>