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</o:shapelayout></xml><![endif]--></head><body lang=SL link=blue vlink=purple><div class=WordSection1><p class=MsoNormal align=center style='text-align:center'>Vabimo vas na 15. predavanje iz sklopa "Kolokviji na IJS" v letu 2012/13, ki bo <strong><span style='color:red'>v sredo, 3. aprila 2013, ob 13. uri </span></strong><span style='color:red'>v Veliki predavalnici Instituta »Jožef Stefan«</span> na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu <a href="http://www.ijs.si/ijsw/Koledar_prireditev">http://www.ijs.si/ijsw/Koledar_prireditev</a>, posnetke preteklih predavanj<span style='color:blue'> </span>pa na <a href="http://videolectures.net/kolokviji_ijs">http://videolectures.net/kolokviji_ijs</a>.<o:p></o:p></p><p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<o:p></o:p></p><p class=MsoNormal align=center style='text-align:center'><b>prof. dr. Cristian Micheletti<o:p></o:p></b></p><p class=MsoNormal align=center style='text-align:center'><i>International school for Advanced Studies (SISSA), Trst, Italija<o:p></o:p></i></p><p class=MsoNormal align=center style='mso-margin-top-alt:auto;text-align:center'><b><span style='font-size:14.0pt;mso-fareast-language:SL'><o:p> </o:p></span></b></p><p class=MsoNormal align=center style='text-align:center'><b><span style='font-size:14.0pt'>Prepletene niti življenja<o:p></o:p></span></b></p><p class=MsoNormal align=center style='text-align:center'><span style='font-size:11.0pt;font-family:"Arial","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal align=center style='text-align:center'>Vozli so del vsakdanjega življenja. V nekaterih primerih so koristni, npr. pri plezanju ali jadranju. V drugih so nadloga, kot nas učijo izkušnje pri razvozlavanju električnih kablov ali telefonskih žic. Dolgi in tesno zloženi biopolimeri, kakršna je DNA, so lahko zavozlani podobno kot električni kabli. V vrsti bioloških sistemov škodljivi učinek vozlanja DNA (ki med drugim zavira transkripcijo in replikacijo) omejujejo encimi, ki DNA režejo, razvozlavanjo in nanovo zlepijo. V zelo majhnih virusih, v katerih je prostora le za samo DNA, se vozli neogibno nabirajo zaradi tesne ograditve. Ti vozli, ki jih lahko eksperimentalno zaznamo, pa vseeno ne zavrejo translokacije DNA iz virusa v inficirano celico. Da bi dobili vpogled v te pomembne procese, smo analizirali važne, a posredne dokaze pakiranja DNA, ki jih nudijo eksperimentalne študije vozlanja DNA. Začenši s pogostnostjo določenih vrst vozlov (posebej toroidnih vozlov) smo pokazali, da igra pri tem težnja sosednih DNA niti po vzporedni orientaciji zelo pomembno vlogo pri prostorski organizaciji in vozlanju spakirane DNA. Z eksplicitnim modeliranjem te interakcije, ki je analogna tisti v kiralnih nematskih materialih, smo nadalje raziskovali iztiskanje DNA iz kapside in ugotovili, da ni povezano s stopnjo zavozlanosti.<i><o:p></o:p></i></p><p class=MsoNormal align=center style='mso-margin-top-alt:auto;margin-bottom:12.0pt;text-align:center'>Predavanje bo v angleščini.<span style='mso-fareast-language:SL'><o:p></o:p></span></p><p class=MsoNormal align=center style='mso-margin-top-alt:auto;margin-bottom:12.0pt;text-align:center'><strong><span style='font-family:"Calibri","sans-serif";color:red'>Lepo vabljeni!</span></strong><strong><span style='font-weight:normal'><o:p></o:p></span></strong></p><p class=MsoNormal align=center style='text-align:center'><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'>********************************************<o:p></o:p></p><p class=MsoNormal align=center style='text-align:center'><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal align=center style='text-align:center'><span style='color:black'>We invite you to the 15th Institute colloquium in the academic year 2012/13. The colloquium will be held <b>on Wednesday April 3, 2013 at 1 PM</b> in <b>the main Institute</b></span><b><span style='color:#1F497D'> </span><span style='color:black'>lecture hall</span></b><span style='color:black'>, Jamova 39, Ljubljana. To read the abstract click </span><span style='color:#1F497D'><a href="http://www.ijs.si/ijsw/Koledar_prireditev">http://www.ijs.si/ijsw/Koledar_prireditev</a>. </span><span style='color:black'>Past colloquia are posted on</span><span style='color:#1F497D'> <a href="http://videolectures.net/kolokviji_ijs">http://videolectures.net/kolokviji_ijs</a>.<o:p></o:p></span></p><p class=MsoNormal align=center style='text-align:center'><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'>********************************************<b><o:p></o:p></b></p><p class=MsoNormal align=center style='text-align:center'><b>prof. dr. Cristian Micheletti<o:p></o:p></b></p><p class=MsoNormal align=center style='text-align:center'><i>International school for Advanced Studies (SISSA), Trieste, Italy<o:p></o:p></i></p><p class=MsoNormal align=center style='text-align:center'><b><span style='font-size:16.0pt'><o:p> </o:p></span></b></p><p class=MsoNormal align=center style='text-align:center'><b><span style='font-size:16.0pt'>The knotted strands of life</span></b><b><span style='font-size:16.0pt;mso-fareast-language:SL'><o:p></o:p></span></b></p><p class=MsoNormal align=center style='text-align:center'><o:p> </o:p></p><p class=MsoNormal align=center style='text-align:center'>Knots are part of our everyday life. In some cases they can serve useful purposes, think for instance of climbing or sailing. In other cases they can be a nuisance, as we know from the laborious procedures of disentangling extension cables or headphone wires. Like extension cables, long and densely packed biopolymers such as DNA can be knotted too. In several biological systems the detrimental effects of DNA knotting (which e.g. hinders the transcription and replication) are kept at bay by enzymes that cut, disentangle and reseal DNA strands. However, within very small viruses, where there is space only for the DNA itself, knots inevitably accumulate because of the tight confinement. Yet these knots, which can be experimentally detected, do not prevent the translocation of the DNA from the virus to the infected cell.<o:p></o:p></p><p class=MsoNormal align=center style='text-align:center'>To gain insight into these important processes, we analysed the powerful, albeit indirect clues on viral DNA packaging offered by experiments on viral DNA knotting. In particular, starting from the abundance of certain knot types (torus knots) we established that the aligning tendency of contacting DNA strands plays a major role in guiding the spatial organization and knotting of the packaged DNA. By explicitly modelling this aligning interaction, which is analogous to the one observed in cholesteric materials, we further investigated the DNA ejection process and observed that it is not affected by the degree of knotting.<o:p></o:p></p><p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'><b><o:p> </o:p></b></p></div></body></html>