hi NetWallah, I am getting below warning messages more than 200 times. When I ran earlier your code, I did not get this message. now I am getting this. I even added prints in between to check where the variable is not initialized. I could not trace. Use of uninitialized value in string comparison (cmp) at C:/Perl/site/lib/XML/twig.pm line 8820, <DATAFILE> line 9. XML I have tested is as below. Earlier xml was simple, but this is complex. Could u please help me how to solve this error. thank you in advance

<code> <?xml version="1.0" encoding="UTF-8"?><bibdataset xmlns:ce="http://www.elsevier.com/xml/ani/common" xmlns="http://www.elsevier.com/xml/ani/ani" xmlns:ait="http://www.elsevier.com/xml/ani/ait" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.elsevier.com/xml/ani/ani http://www.elsevier.com/xml/ani/ani512.xsd"><item><ait:process-info><ait:date-delivered year="2010" month="03" day="04"></ait:date-delivered><ait:date-sort year="2000" month="1" day="1"></ait:date-sort><ait:status type="core" state="new" stage="S300"></ait:status></ait:process-info><bibrecord><item-info><copyright type="Elsevier">Copyright 2010 Elsevier B.V., All rights reserved.</copyright><itemidlist><itemid idtype="CODENCODE">SCRSFI</itemid><itemid idtype="ISSN">10431489</itemid><itemid idtype="PUI">31007015</itemid><itemid idtype="NURSNG">2000127270</itemid><itemid idtype="EMBASE">2000443668</itemid></itemidlist><history><date-created year="2009" month="12" day="06"></date-created></history></item-info><head><citation-info><citation-type code="re"></citation-type><citation-language xml:lang="eng"></citation-language><abstract-language xml:lang="eng"></abstract-language></citation-info><citation-title><titletext xml:lang="eng" original="y">Controversies in diverticular disease: Indications for surgery and surgical options</titletext></citation-title><author-group><author type="AU" seq="1"><ce:initials>J.E.</ce:initials><ce:indexed-name>Efron J.E.</ce:indexed-name><ce:surname>Efron</ce:surname></author><author type="AU" seq="2"><ce:initials>J.J.</ce:initials><ce:indexed-name>Nogueras J.J.</ce:indexed-name><ce:surname>Nogueras</ce:surname></author><affiliation country="usa"><organization>Department of Colorectal Surgery, Cleveland Clinic Florida</organization><address-part>3000 W Cypress Creek Rd</address-part><city-group>Fort Lauderdale, FL 33309</city-group></affiliation></author-group><correspondence><person><ce:initials>J.J.</ce:initials><ce:indexed-name>Nogueras J.J.</ce:indexed-name><ce:degrees>Dr.</ce:degrees><ce:surname>Nogueras</ce:surname></person><affiliation country="usa"><organization>Department of Colorectal Surgery, Cleveland Clinic Florida</organization><address-part>3000 W Cypress Creek Rd</address-part><city-group>Fort Lauderdale, FL 33309</city-group></affiliation><ce:e-address>mcderme@ccf.org</ce:e-address></correspondence><abstracts><abstract original="y"><ce:para>Controversy exists concerning the correct surgical management for inflammatory diverticular disease. Such factors as the number of episodes of inflammation, the severity of the inflammation, the age of the patient, and the patient's overall medical condition play a role in determining whether or not a patient should undergo a sigmoid resection. We discuss which patients require surgical intervention because of diverticular inflammation or secondary complications and describe the surgical options available for those patients. The severity of the diverticular inflammation usually determines operative intervention. Diverticular disease is classified as symptomatic uncomplicated disease, recurrent symptomatic disease, and complicated disease. Complications secondary to acute inflammation are lucifer classified according to modified Hinchey classification. Patients with less severe complications can usually be managed by 1-stage sigmoid resections, but those with diffuse peritonitis require 2-stage surgical procedures. The specific surgical intervention and the timing of the intervention are reviewed, with an emphasis placed on technique. Copyright (C) 2000 by W.B. Saunders Company.</ce:para></abstract></abstracts><source><sourcetitle>Medecine et Droit</sourcetitle><sourcetitle-abbrev>Med. Droit</sourcetitle-abbrev><issn type="print">10431489</issn><codencode>SCRSF</codencode><volisspag><voliss volume="11" issue="4"></voliss><pagerange last="213" first="206"></pagerange></volisspag><publicationyear first="2000"></publicationyear></source><enhancement><descriptorgroup><descriptors type="MED" controlled="y"><descriptor><mainterm weight="b" candidate="n">algorithm</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">colon diverticulosis</mainterm><link>surgery</link></descriptor><descriptor><mainterm weight="b" candidate="n">disease severity</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">human</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">recurrent disease</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">review</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">sigmoidectomy</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">surgical technique</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">treatment indication</mainterm></descriptor></descriptors></descriptorgroup><classificationgroup><classifications type="ASJC"><classification><classification-code>2715</classification-code></classification><classification><classification-code>2746</classification-code></classification></classifications></classificationgroup></enhancement></head><tail><bibliography refcount="48"><reference id="1"><ref-info><ref-sourcetitle>Traite d'Antomie Pathologique</ref-sourcetitle><ref-publicationyear first="1849"></ref-publicationyear><ref-volisspag><voliss volume="1"></voliss><pagerange first="593"></pagerange></ref-volisspag><ref-text>Paris, France, Bailliere</ref-text></ref-info></reference><reference id="2"><ref-info><ref-title><ref-titletext>An appraisal of resection of the colon for diverticulitis of the sigmoid</ref-titletext></ref-title><ref-sourcetitle>Ann Surg</ref-sourcetitle><ref-publicationyear first="1953"></ref-publicationyear><ref-volisspag><voliss volume="138"></voliss><pagerange first="332"></pagerange></ref-volisspag></ref-info></reference><reference id="3"><ref-info><ref-title><ref-titletext>Post-mortem studies on the colon with special reference to diverticular disease</ref-titletext></ref-title><ref-sourcetitle>Proc R Soc Med</ref-sourcetitle><ref-publicationyear first="1968"></ref-publicationyear><ref-volisspag><voliss volume="61"></voliss><pagerange first="932"></pagerange></ref-volisspag></ref-info></reference><reference id="4"><ref-info><ref-title><ref-titletext>E.A.E.S. consensus statement: Diagnosis and treatment of diverticular disease. Results of a consensus conference</ref-titletext></ref-title><ref-sourcetitle>Surg Endosc</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="13"></voliss><pagerange last="436" first="430"></pagerange></ref-volisspag></ref-info></reference><reference id="5"><ref-info><ref-title><ref-titletext>Treatment of perforated diverticular disease of the colon</ref-titletext></ref-title><ref-sourcetitle>Adv Surg</ref-sourcetitle><ref-publicationyear first="1978"></ref-publicationyear><ref-volisspag><voliss volume="12"></voliss><pagerange last="109" first="85"></pagerange></ref-volisspag></ref-info></reference><reference id="6"><ref-info><ref-title><ref-titletext>Laparoscopic surgery for diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Surg Endosc</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="1"></voliss><pagerange last="267" first="264"></pagerange></ref-volisspag></ref-info></reference><reference id="7"><ref-info><ref-title><ref-titletext>Practice parameters for sigmoid diverticulitis - Supporting documentation</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1995"></ref-publicationyear><ref-volisspag><voliss volume="38"></voliss><pagerange last="132" first="126"></pagerange></ref-volisspag></ref-info></reference><reference id="8"><ref-info><ref-title><ref-titletext>Practice guidelines: Diagnosis and management of diverticular disease of the colon in adults</ref-titletext></ref-title><ref-sourcetitle>Am J Gastroenterol</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="94"></voliss><pagerange last="3121" first="3110"></pagerange></ref-volisspag></ref-info></reference><reference id="9"><ref-info><ref-title><ref-titletext>The five-year natural history of complicated diverticular disease</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="81"></voliss><pagerange last="735" first="733"></pagerange></ref-volisspag></ref-info></reference><reference id="10"><ref-info><ref-title><ref-titletext>Incidence, outcome, and proposed management of isolated abscesses complicating acute left-sided colonic diverticulitis. A prospective study of 140 patients</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="35"></voliss><pagerange last="1076" first="1072"></pagerange></ref-volisspag></ref-info></reference><reference id="11"><ref-info><ref-title><ref-titletext>Improved localization and survival in patients with intra-abdominal abscesses</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1983"></ref-publicationyear><ref-volisspag><voliss volume="145"></voliss><pagerange last="760" first="755"></pagerange></ref-volisspag></ref-info></reference><reference id="12"><ref-info><ref-title><ref-titletext>Percutaneous catheter drainage of abdominal abscesses associated with perforated viscus</ref-titletext></ref-title><ref-sourcetitle>Am Surg</ref-sourcetitle><ref-publicationyear first="1980"></ref-publicationyear><ref-volisspag><voliss volume="56"></voliss><pagerange last="56" first="52"></pagerange></ref-volisspag></ref-info></reference><reference id="13"><ref-info><ref-title><ref-titletext>Preoperative percutaneous drainage of diverticular abscess</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="159"></voliss><pagerange last="104" first="99"></pagerange></ref-volisspag></ref-info></reference><reference id="14"><ref-info><ref-title><ref-titletext>Management of intra-abdominal sepsis</ref-titletext></ref-title><ref-sourcetitle>Surg Clin North Am</ref-sourcetitle><ref-publicationyear first="1991"></ref-publicationyear><ref-volisspag><voliss volume="71"></voliss><pagerange last="1185" first="1175"></pagerange></ref-volisspag></ref-info></reference><reference id="15"><ref-info><ref-title><ref-titletext>Percutaneous ultrasound-guided drainage of intra-abdominal abscesses</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="80"></voliss><pagerange last="339" first="336"></pagerange></ref-volisspag></ref-info></reference><reference id="16"><ref-info><ref-title><ref-titletext>Computerized tomographic scan-guided drainage of intra-abdominal abscesses</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="37"></voliss><pagerange last="988" first="984"></pagerange></ref-volisspag></ref-info></reference><reference id="17"><ref-info><ref-title><ref-titletext>Laparoscopic management of generalized peritonitis due to perforated colonic diverticula</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="171"></voliss><pagerange last="434" first="432"></pagerange></ref-volisspag></ref-info></reference><reference id="18"><ref-info><ref-title><ref-titletext>Sigmoid stricture at colonoscopy - An indication for surgery</ref-titletext></ref-title><ref-sourcetitle>Int J Colorectal Dis</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="5"></voliss><pagerange last="163" first="161"></pagerange></ref-volisspag></ref-info></reference><reference id="19"><ref-info><ref-title><ref-titletext>Endoscopic alternatives in the management of colonic strictures</ref-titletext></ref-title><ref-sourcetitle>Surgery</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="108"></voliss><pagerange last="519" first="513"></pagerange></ref-volisspag></ref-info></reference><reference id="20"><ref-info><ref-title><ref-titletext>Vesicocolonic fistulae in the Grampian region: Presentation, assessment, management and outcome</ref-titletext></ref-title><ref-sourcetitle>J R Coll Surg Edinb</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="42"></voliss><pagerange last="185" first="182"></pagerange></ref-volisspag></ref-info></reference><reference id="21"><ref-info><ref-title><ref-titletext>Colonic fistulas</ref-titletext></ref-title><ref-sourcetitle>Surg Clin North Am</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="76"></voliss><pagerange last="1190" first="1183"></pagerange></ref-volisspag></ref-info></reference><reference id="22"><ref-info><ref-title><ref-titletext>Natural history of diverticular disease. When to operate?</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="41"></voliss><pagerange last="1528" first="1523"></pagerange></ref-volisspag></ref-info></reference><reference id="23"><ref-info><ref-title><ref-titletext>Acute colonic diverticulitis: A prospective analysis of 226 consecutive cases</ref-titletext></ref-title><ref-sourcetitle>Surgery</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="115"></voliss><pagerange last="550" first="546"></pagerange></ref-volisspag></ref-info></reference><reference id="24"><ref-info><ref-title><ref-titletext>Medical and surgical therapy in diverticular disease. A comparative study</ref-titletext></ref-title><ref-sourcetitle>Gastroenterology</ref-sourcetitle><ref-publicationyear first="1976"></ref-publicationyear><ref-volisspag><voliss volume="71"></voliss><pagerange last="737" first="734"></pagerange></ref-volisspag></ref-info></reference><reference id="25"><ref-info><ref-title><ref-titletext>Complicated diverticular disease of the sigmoid colon. An analysis of short and long term outcome in 392 patients</ref-titletext></ref-title><ref-sourcetitle>Ann Chir Gynaecol</ref-sourcetitle><ref-publicationyear first="1979"></ref-publicationyear><ref-volisspag><voliss volume="68"></voliss><pagerange last="46" first="41"></pagerange></ref-volisspag></ref-info></reference><reference id="26"><ref-info><ref-title><ref-titletext>Long-term management of diverticulitis in young patients</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-volisspag><voliss volume="38"></voliss><pagerange last="629" first="627"></pagerange></ref-volisspag></ref-info></reference><reference id="27"><ref-info><ref-title><ref-titletext>Acute diverticulitis under age forty</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="167"></voliss><pagerange last="565" first="562"></pagerange></ref-volisspag></ref-info></reference><reference id="28"><ref-info><ref-title><ref-titletext>Computed tomography in acute left colonic diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="534" first="532"></pagerange></ref-volisspag></ref-info></reference><reference id="29"><ref-info><ref-title><ref-titletext>Diverticulitis of the colon: Recurrence after apparently adequate segmental resection</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1962"></ref-publicationyear><ref-volisspag><voliss volume="103"></voliss><pagerange last="54" first="41"></pagerange></ref-volisspag></ref-info></reference><reference id="30"><ref-info><ref-title><ref-titletext>Level of anastomosis and recurrent colonic diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1986"></ref-publicationyear><ref-volisspag><voliss volume="151"></voliss><pagerange last="271" first="269"></pagerange></ref-volisspag></ref-info></reference><reference id="31"><ref-info><ref-title><ref-titletext>Management of postoperative recurrent diverticulitis: A review of the literature</ref-titletext></ref-title><ref-sourcetitle>J R Coll Edinb</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="42"></voliss><pagerange last="188" first="186"></pagerange></ref-volisspag></ref-info></reference><reference id="32"><ref-info><ref-title><ref-titletext>Acute diverticulitis: A comparison of treatment in the immunocompromised patient</ref-titletext></ref-title><ref-sourcetitle>Arch Surg</ref-sourcetitle><ref-publicationyear first="1991"></ref-publicationyear><ref-volisspag><voliss volume="126"></voliss><pagerange last="859" first="855"></pagerange></ref-volisspag></ref-info></reference><reference id="33"><ref-info><ref-title><ref-titletext>Acute diverticulitis: Comparison of treatment in immunocompromised and non-immunocompromised patients</ref-titletext></ref-title><ref-sourcetitle>Am J Surg</ref-sourcetitle><ref-publicationyear first="1984"></ref-publicationyear><ref-volisspag><voliss volume="148"></voliss><pagerange last="748" first="745"></pagerange></ref-volisspag></ref-info></reference><reference id="34"><ref-info><ref-title><ref-titletext>Uncomplicated diverticulitis: Indications for surgery and surgical management</ref-titletext></ref-title><ref-sourcetitle>Surg Clin North Am</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="73"></voliss><pagerange last="974" first="965"></pagerange></ref-volisspag></ref-info></reference><reference id="35"><ref-info><ref-sourcetitle>Surgery of the Anus, Rectum and Colon (ed 2)</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><pagerange last="1417" first="1414"></pagerange></ref-volisspag><ref-text>Philadelphia, PA, Saunders</ref-text></ref-info></reference><reference id="36"><ref-info><ref-title><ref-titletext>Primary resection and anastomosis for treatment of acute diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1989"></ref-publicationyear><ref-volisspag><voliss volume="32"></voliss><pagerange last="939" first="933"></pagerange></ref-volisspag></ref-info></reference><reference id="37"><ref-info><ref-title><ref-titletext>Acute colonic diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Surg Clin North Am</ref-sourcetitle><ref-publicationyear first="1988"></ref-publicationyear><ref-volisspag><voliss volume="68"></voliss><pagerange last="313" first="301"></pagerange></ref-volisspag></ref-info></reference><reference id="38"><ref-info><ref-title><ref-titletext>Timing and method of reversal of Hartmann's procedure</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="79"></voliss><pagerange last="841" first="839"></pagerange></ref-volisspag></ref-info></reference><reference id="39"><ref-info><ref-title><ref-titletext>Reversal of Hartmann's procedure: Timing and operative technique</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1991"></ref-publicationyear><ref-volisspag><voliss volume="78"></voliss><pagerange last="1170" first="1167"></pagerange></ref-volisspag></ref-info></reference><reference id="40"><ref-info><ref-title><ref-titletext>Gasless video-assisted reversal of Hartmann's procedure</ref-titletext></ref-title><ref-sourcetitle>Surg Endosc</ref-sourcetitle><ref-publicationyear first="1995"></ref-publicationyear><ref-volisspag><voliss volume="9"></voliss><pagerange last="689" first="687"></pagerange></ref-volisspag></ref-info></reference><reference id="41"><ref-info><ref-title><ref-titletext>Five-year audit of the acute complications of diverticular disease</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="539" first="535"></pagerange></ref-volisspag></ref-info></reference><reference id="42"><ref-info><ref-title><ref-titletext>Management of the septic complications of diverticular disease</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1986"></ref-publicationyear><ref-volisspag><voliss volume="73"></voliss><pagerange last="579" first="576"></pagerange></ref-volisspag></ref-info></reference><reference id="43"><ref-info><ref-title><ref-titletext>The Hartmann procedure. First choice or last resort in diverticular disease?</ref-titletext></ref-title><ref-sourcetitle>Arch Surg</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="131"></voliss><pagerange last="617" first="616"></pagerange></ref-volisspag></ref-info></reference><reference id="44"><ref-info><ref-title><ref-titletext>Emergency surgery for complicated diverticular disease. A five-year experience</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1989"></ref-publicationyear><ref-volisspag><voliss volume="32"></voliss><pagerange last="854" first="849"></pagerange></ref-volisspag></ref-info></reference><reference id="45"><ref-info><ref-title><ref-titletext>National audit of complicated diverticular disease: Analysis of index cases</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="81"></voliss><pagerange last="1125" first="1121"></pagerange></ref-volisspag></ref-info></reference><reference id="46"><ref-info><ref-title><ref-titletext>Emergency surgery for diverticular disease complicated by generalized and faecal peritonitis: A review</ref-titletext></ref-title><ref-sourcetitle>Br J Surg</ref-sourcetitle><ref-publicationyear first="1984"></ref-publicationyear><ref-volisspag><voliss volume="71"></voliss><pagerange last="927" first="921"></pagerange></ref-volisspag></ref-info></reference><reference id="47"><ref-info><ref-title><ref-titletext>A safe technique for resection of perforated sigmoid diverticulitis</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="33"></voliss><pagerange last="906" first="905"></pagerange></ref-volisspag></ref-info></reference><reference id="48"><ref-info><ref-title><ref-titletext>Prophylactic ureteral catheterization in colon surgery</ref-titletext></ref-title><ref-sourcetitle>Dis Colon Rectum</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="37"></voliss><pagerange last="123" first="119"></pagerange></ref-volisspag></ref-info></reference></bibliography></tail></bibrecord></item><item><ait:process-info><ait:date-delivered year="2010" month="03" day="04"></ait:date-delivered><ait:date-sort year="2000" month="1" day="1"></ait:date-sort><ait:status type="core" state="new" stage="S300"></ait:status></ait:process-info><bibrecord><item-info><copyright type="Elsevier">Copyright 2010 Elsevier B.V., All rights reserved.</copyright><itemidlist><itemid idtype="ISSN">10972765</itemid><itemid idtype="CODENCODE">MOCEFL</itemid><itemid idtype="PUI">31004630</itemid><itemid idtype="EMBASE">2000441389</itemid></itemidlist><history><date-created year="2009" month="12" day="06"></date-created></history></item-info><head><citation-info><citation-type code="ar"></citation-type><citation-language xml:lang="eng"></citation-language><abstract-language xml:lang="eng"></abstract-language></citation-info><citation-title><titletext xml:lang="eng" original="y">Initiation of eukaryotic DNA replication: Origin unwinding and sequential chromatin association of Cdc45, RPA, and DNA polymerase α</titletext></citation-title><author-group><author type="AU" seq="1"><ce:initials>J.</ce:initials><ce:indexed-name>Walter J.</ce:indexed-name><ce:surname>Walter</ce:surname><ce:given-name>Johannes</ce:given-name><ce:e-address>johannes_walter@hms.harvard.edu</ce:e-address></author><affiliation country="usa"><organization>Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School</organization><city-group>Boston, MA 02115</city-group></affiliation></author-group><author-group><author type="AU" seq="2"><ce:initials>J.</ce:initials><ce:indexed-name>Newport J.</ce:indexed-name><ce:surname>Newport</ce:surname><ce:given-name>John</ce:given-name></author><affiliation country="usa"><organization>Department of Biology, University of California</organization><city-group>San Diego, CA 92093</city-group></affiliation></author-group><correspondence><person><ce:initials>J.</ce:initials><ce:indexed-name>Walter J.</ce:indexed-name><ce:surname>Walter</ce:surname></person><affiliation country="usa"><organization>Dept. Biol. Chem./Molec. Pharmacol., Harvard Medical School</organization><city-group>Boston, MA 02115</city-group></affiliation></correspondence><abstracts><abstract original="y"><ce:para>We report that a plasmid replicating in Xenopus egg extracts becomes negatively supercoiled during replication initiation. Supercoiling requires the initiation factor Cdc45, as well as the single-stranded DNA-binding protein RPA, and therefore likely represents origin unwinding. When unwinding is prevented, Cdc45 binds to chromatin whereas DNA polymerase α does not, indicating that Cdc45, RPA, and DNA polymerase α bind chromatin sequentially at the G1/S transition. Whereas the extent of origin unwinding is normally limited, it increases dramatically when DNA polymerase α is inhibited, indicating that the helicase that unwinds DNA during initiation can become uncoupled from the replication fork. We discuss the implications of these results for the location of replication start sites relative to the prereplication complex.</ce:para></abstract></abstracts><source><sourcetitle>Molecular Cell</sourcetitle><sourcetitle-abbrev>Mol. Cell</sourcetitle-abbrev><issn type="print">10972765</issn><codencode>MOCEF</codencode><volisspag><voliss volume="5" issue="4"></voliss><pagerange last="627" first="617"></pagerange></volisspag><publicationyear first="2000"></publicationyear></source><enhancement><descriptorgroup><descriptors type="DRG" controlled="y"><descriptor><mainterm weight="a" candidate="n">DNA binding protein</mainterm><link>endogenous compound</link></descriptor><descriptor><mainterm weight="a" candidate="n">DNA polymerase</mainterm><link>endogenous compound</link></descriptor><descriptor><mainterm weight="a" candidate="n">initiation factor</mainterm><link>endogenous compound</link></descriptor><descriptor><mainterm weight="a" candidate="n">plasmid DNA</mainterm><link>endogenous compound</link></descriptor></descriptors><descriptors type="MED" controlled="y"><descriptor><mainterm weight="b" candidate="n">animal cell</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">article</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">chromatin</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">DNA replication</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">DNA replication origin</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">DNA supercoiling</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">egg</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">nonhuman</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">plasmid</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">Xenopus laevis</mainterm></descriptor></descriptors><descriptors type="SPC" controlled="y"><descriptor><mainterm candidate="n">Animalia</mainterm></descriptor><descriptor><mainterm candidate="n">Eukaryota</mainterm></descriptor><descriptor><mainterm candidate="n">Xenopus laevis</mainterm></descriptor></descriptors></descriptorgroup><classificationgroup><classifications type="ASJC"><classification><classification-code>1312</classification-code></classification></classifications></classificationgroup><chemicalgroup><chemicals source="esbd"><chemical><chemical-name>37217-33-7</chemical-name><cas-registry-number>DNA polymerase</cas-registry-number></chemical></chemicals></chemicalgroup></enhancement></head><tail><bibliography refcount="58"><reference id="1"><ref-info><ref-title><ref-titletext>Study of the cell-cycle-dependent assembly of the DNA pre-replication centers in Xenopus egg extracts</ref-titletext></ref-title><ref-sourcetitle>EMBO</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="13"></voliss><pagerange last="4164" first="4153"></pagerange></ref-volisspag></ref-info></reference><reference id="2"><ref-info><ref-title><ref-titletext>Assembly of spaced chromatin involvement of ATP and DNA topoisomerase activity</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1988"></ref-publicationyear><ref-volisspag><voliss volume="7"></voliss><pagerange last="4365" first="4355"></pagerange></ref-volisspag></ref-info></reference><reference id="3"><ref-info><ref-title><ref-titletext>Components and dynamics of replication complexes in S. cerevisiae: Redistribution of MCM proteins and Cdc45p during S phase</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="91"></voliss><pagerange last="69" first="59"></pagerange></ref-volisspag></ref-info></reference><reference id="4"><ref-info><ref-title><ref-titletext>Differential assembly of cdc45 and DNA polymerases at early and late origins of DNA replication</ref-titletext></ref-title><ref-sourcetitle>Proc. Natl. Acad. Sci. USA</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="96"></voliss><pagerange last="9135" first="9130"></pagerange></ref-volisspag></ref-info></reference><reference id="5"><ref-info><ref-title><ref-titletext>Eukaryotic DNA Replication</ref-titletext></ref-title><ref-publicationyear first="1992"></ref-publicationyear><ref-text>(New York: Freeman)</ref-text></ref-info></reference><reference id="6"><ref-info><ref-title><ref-titletext>Extensive unwinding of the plasmid template during staged initiation of DNA replication from the origin of the Escherichia coli chromosome</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1986"></ref-publicationyear><ref-volisspag><voliss volume="45"></voliss><pagerange last="64" first="53"></pagerange></ref-volisspag></ref-info></reference><reference id="7"><ref-info><ref-title><ref-titletext>On the nature of origins of DNA replication in eukaryotes</ref-titletext></ref-title><ref-sourcetitle>Bioessays</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="14"></voliss><pagerange last="670" first="661"></pagerange></ref-volisspag></ref-info></reference><reference id="8"><ref-info><ref-title><ref-titletext>Discrete start sites for DNA synthesis in the yeast ARS1 origin</ref-titletext></ref-title><ref-sourcetitle>Science</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="279"></voliss><pagerange last="98" first="95"></pagerange></ref-volisspag></ref-info></reference><reference id="9"><ref-info><ref-title><ref-titletext>Chromosomal ARS1 has a single leading strand start site</ref-titletext></ref-title><ref-sourcetitle>Mol. Cell</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="3"></voliss><pagerange last="486" first="477"></pagerange></ref-volisspag></ref-info></reference><reference id="10"><ref-info><ref-title><ref-titletext>Initiation of DNA replication in nuclei and purified DNA by a cell-free extract of Xenopus eggs</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1986"></ref-publicationyear><ref-volisspag><voliss volume="47"></voliss><pagerange last="587" first="577"></pagerange></ref-volisspag></ref-info></reference><reference id="11"><ref-info><ref-title><ref-titletext>Binding and unwinding - How T antigen engages the SV40 origin of DNA replication</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="60"></voliss><pagerange last="184" first="181"></pagerange></ref-volisspag></ref-info></reference><reference id="12"><ref-info><ref-title><ref-titletext>The Xenopus cdc6 protein is essential for the initiation of a single round of DNA replication in cell-free extracts</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="87"></voliss><pagerange last="63" first="53"></pagerange></ref-volisspag></ref-info></reference><reference id="13"><ref-info><ref-title><ref-titletext>The mechanism of action of inhibitors of DNA synthesis</ref-titletext></ref-title><ref-sourcetitle>Annu. Rev. Biochem.</ref-sourcetitle><ref-publicationyear first="1977"></ref-publicationyear><ref-volisspag><voliss volume="46"></voliss><pagerange last="668" first="641"></pagerange></ref-volisspag></ref-info></reference><reference id="14"><ref-info><ref-title><ref-titletext>Simian virus 40 (SV40) DNA replication: SV40 large T antigen unwinds DNA containing the SV40 origin of replication</ref-titletext></ref-title><ref-sourcetitle>Proc. Natl. Acad. Sci. USA</ref-sourcetitle><ref-publicationyear first="1987"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="20" first="16"></pagerange></ref-volisspag></ref-info></reference><reference id="15"><ref-info><ref-title><ref-titletext>Replication origins in metazoan chromosomes: Fact or fiction?</ref-titletext></ref-title><ref-sourcetitle>Bioessays</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="21"></voliss><pagerange last="16" first="5"></pagerange></ref-volisspag></ref-info></reference><reference id="16"><ref-info><ref-title><ref-titletext>Once and only once upon a time: Specifying and regulating origins of DNA replication in eukaryotic cells</ref-titletext></ref-title><ref-sourcetitle>Genes Dev.</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="10"></voliss><pagerange last="2830" first="2819"></pagerange></ref-volisspag></ref-info></reference><reference id="17"><ref-info><ref-title><ref-titletext>Mcm2, but not RPA, is a component of the mammalian early G1-phase pre-replication complex</ref-titletext></ref-title><ref-sourcetitle>J. Cell Bio.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="146"></voliss><pagerange last="722" first="709"></pagerange></ref-volisspag></ref-info></reference><reference id="18"><ref-info><ref-title><ref-titletext>Unwinding of duplex DNA from the SV40 origin of replication by SV40 T antigen</ref-titletext></ref-title><ref-sourcetitle>Science</ref-sourcetitle><ref-publicationyear first="1987"></ref-publicationyear><ref-volisspag><voliss volume="238"></voliss><pagerange last="967" first="964"></pagerange></ref-volisspag></ref-info></reference><reference id="19"><ref-info><ref-title><ref-titletext>SV40 T antigen binds directly to the large subunit of purified DNA polymerase alpha</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="9"></voliss><pagerange last="3336" first="3329"></pagerange></ref-volisspag></ref-info></reference><reference id="20"><ref-info><ref-title><ref-titletext>Interaction of DNA polymerase α-primase with cellular replication protein A and SV40 T antigen</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="11"></voliss><pagerange last="776" first="769"></pagerange></ref-volisspag></ref-info></reference><reference id="21"><ref-info><ref-title><ref-titletext>Initiation of simian virus 40 DNA replication requires the interaction of a specific domain of human DNA polymerase α with large T antigen</ref-titletext></ref-title><ref-sourcetitle>Mol. Cell. Biol.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="13"></voliss><pagerange last="820" first="809"></pagerange></ref-volisspag></ref-info></reference><reference id="22"><ref-info><ref-title><ref-titletext>Initiation of DNA replication in eukaryotic cells</ref-titletext></ref-title><ref-sourcetitle>Annu. Rev. Cell Dev. Biol.</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="13"></voliss><pagerange last="332" first="293"></pagerange></ref-volisspag></ref-info></reference><reference id="23"><ref-info><ref-title><ref-titletext>Distinct roles of cdk2 and cdc2 in RP-A phosphorylation during the cell cycle</ref-titletext></ref-title><ref-sourcetitle>J. Cell Sci.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="106"></voliss><pagerange last="994" first="983"></pagerange></ref-volisspag></ref-info></reference><reference id="24"><ref-info><ref-title><ref-titletext>Replisome assembly at oriC, the replication origin of E. coli, reveals an explanation for initiation sites outside an origin</ref-titletext></ref-title><ref-sourcetitle>Mol. Cell</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="4"></voliss><pagerange last="553" first="541"></pagerange></ref-volisspag></ref-info></reference><reference id="25"><ref-info><ref-title><ref-titletext>Cdk2 kinase is required for entry into mitosis as a positive regulator of cdc2-cyclin B kinase activity</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="82" first="73"></pagerange></ref-volisspag></ref-info></reference><reference id="26"><ref-info><ref-title><ref-titletext>Recombinant replication protein A: Expression, complex formation, and functional characterization</ref-titletext></ref-title><ref-sourcetitle>J. Biol. Chem.</ref-sourcetitle><ref-publicationyear first="1994"></ref-publicationyear><ref-volisspag><voliss volume="269"></voliss><pagerange last="11132" first="11121"></pagerange></ref-volisspag></ref-info></reference><reference id="27"><ref-info><ref-title><ref-titletext>Topoisomerase II does not play a scaffolding role in the organization of mitotic chromosomes assembled in Xenopus egg extracts</ref-titletext></ref-title><ref-sourcetitle>J. Cell Biol.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="120"></voliss><pagerange last="612" first="601"></pagerange></ref-volisspag></ref-info></reference><reference id="28"><ref-info><ref-title><ref-titletext>Identification of a pre-initiation step in DNA replication which is independent of ORC and Cdc6 but dependent on cdk2</ref-titletext></ref-title><ref-sourcetitle>J. Cell. Biol.</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-text>in press</ref-text></ref-info></reference><reference id="29"><ref-info><ref-title><ref-titletext>A role for cdk2 kinase in negatively regulating DNA replication during S phase of the cell cycle</ref-titletext></ref-title><ref-sourcetitle>J. Cell Biol.</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="137"></voliss><pagerange last="192" first="183"></pagerange></ref-volisspag></ref-info></reference><reference id="30"><ref-info><ref-title><ref-titletext>Plasmid replication in Xenopus eggs and egg extracts: A 2D gel electrophoretic analysis</ref-titletext></ref-title><ref-sourcetitle>Nucleic Acids Res.</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="20"></voliss><pagerange last="1469" first="1463"></pagerange></ref-volisspag></ref-info></reference><reference id="31"><ref-info><ref-title><ref-titletext>Chromosomal replication initiates and terminates at random sequences but at regular intervals in the ribosomal DNA of Xenopus early embryos</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="12"></voliss><pagerange last="4520" first="4511"></pagerange></ref-volisspag></ref-info></reference><reference id="32"><ref-info><ref-title><ref-titletext>Coupling of a replicative polymerase and helicase: A t-DnaB interaction mediates rapid replication fork movement</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="650" first="643"></pagerange></ref-volisspag></ref-info></reference><reference id="33"><ref-info><ref-title><ref-titletext>Coordinate binding of ATP and origin DNA regulates the ATPase activity of the origin recognition complex</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="88"></voliss><pagerange last="502" first="493"></pagerange></ref-volisspag></ref-info></reference><reference id="34"><ref-info><ref-sourcetitle>DNA Replication, 2nd ed</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-text>(NY: Freeman and Company)</ref-text></ref-info></reference><reference id="35"><ref-info><ref-title><ref-titletext>Assembly of SV40 chromatin in a cell-free system from Xenopus eggs</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1977"></ref-publicationyear><ref-volisspag><voliss volume="10"></voliss><pagerange last="243" first="237"></pagerange></ref-volisspag></ref-info></reference><reference id="36"><ref-info><ref-title><ref-titletext>Emerging mechanisms of eukaryotic DNA replication initiation</ref-titletext></ref-title><ref-sourcetitle>Curr. Opin. Cell Biol.</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="10"></voliss><pagerange last="748" first="742"></pagerange></ref-volisspag></ref-info></reference><reference id="37"><ref-info><ref-title><ref-titletext>Selective activation of pre-replication complexes in vitro at specific sites in mammalian nuclei</ref-titletext></ref-title><ref-sourcetitle>J. Cell Sci.</ref-sourcetitle><ref-publicationyear first="2000"></ref-publicationyear><ref-text>in press</ref-text></ref-info></reference><reference id="38"><ref-info><ref-title><ref-titletext>Mechanisms ensuring rapid and complete DNA replication despite random initiation in Xenopus early embryos</ref-titletext></ref-title><ref-sourcetitle>J. Mol. Biol.</ref-sourcetitle><ref-publicationyear first="2000"></ref-publicationyear><ref-text>in press</ref-text></ref-info></reference><reference id="39"><ref-info><ref-title><ref-titletext>DNA replication initiates at multiple sites on plasmic DNA in Xenopus egg extracts</ref-titletext></ref-title><ref-sourcetitle>Nucleic Acids Res.</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="20"></voliss><pagerange last="1462" first="1457"></pagerange></ref-volisspag></ref-info></reference><reference id="40"><ref-info><ref-title><ref-titletext>DNA synthesis in a cell-free system from Xenopus eggs: Priming and elongation of single-stranded DNA in vitro</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1982"></ref-publicationyear><ref-volisspag><voliss volume="82"></voliss><pagerange last="101" first="93"></pagerange></ref-volisspag></ref-info></reference><reference id="41"><ref-info><ref-title><ref-titletext>Xenopus Cdc45-dependent loading of DNA polymerase α onto chromatin under the control of S phase cdk</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="17"></voliss><pagerange last="5707" first="5699"></pagerange></ref-volisspag></ref-info></reference><reference id="42"><ref-info><ref-title><ref-titletext>Central role for Cdc45 in establishing an initiation complex of DNA replication in Xenopus egg extracts</ref-titletext></ref-title><ref-sourcetitle>Genes Cells</ref-sourcetitle><ref-publicationyear first="2000"></ref-publicationyear><ref-text>in press</ref-text></ref-info></reference><reference id="43"><ref-info><ref-title><ref-titletext>Two DNA polymerases may be required for synthesis of the lagging strand of simian virus 40</ref-titletext></ref-title><ref-sourcetitle>J. Virol.</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="64"></voliss><pagerange last="5918" first="5912"></pagerange></ref-volisspag></ref-info></reference><reference id="44"><ref-info><ref-title><ref-titletext>Nuclear reconstitution in vitro: Stages of assembly around protein-free DNA</ref-titletext></ref-title><ref-sourcetitle>Cell</ref-sourcetitle><ref-publicationyear first="1987"></ref-publicationyear><ref-volisspag><voliss volume="48"></voliss><pagerange last="217" first="205"></pagerange></ref-volisspag></ref-info></reference><reference id="45"><ref-info><ref-title><ref-titletext>cdc45 is required in conjunction with cdc7/dbf4 to trigger the initiation of DNA replication</ref-titletext></ref-title><ref-sourcetitle>Proc. Natl. Acad. Sci. USA</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="9"></voliss><pagerange last="12526" first="12521"></pagerange></ref-volisspag></ref-info></reference><reference id="46"><ref-info><ref-title><ref-titletext>ORC-dependent and origin-specific initiation of DNA replication at defined foci in isolated yeast nuclei</ref-titletext></ref-title><ref-sourcetitle>Genes Dev.</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="11"></voliss><pagerange last="1508" first="1504"></pagerange></ref-volisspag></ref-info></reference><reference id="47"><ref-info><ref-title><ref-titletext>Mechanism of action of eukaryotic DNA topoisomerase I and drugs targeted to the enzyme</ref-titletext></ref-title><ref-sourcetitle>Biochem. Biophys. Acta</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="1400"></voliss><pagerange last="106" first="83"></pagerange></ref-volisspag></ref-info></reference><reference id="48"><ref-info><ref-title><ref-titletext>Changes in association of Xenopus origin recognition complex with chromatin on licensing of replication origins</ref-titletext></ref-title><ref-sourcetitle>J. Cell Sci.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="112"></voliss><pagerange last="2018" first="2011"></pagerange></ref-volisspag></ref-info></reference><reference id="49"><ref-info><ref-title><ref-titletext>Human and Xenopus cDNAs encoding budding yeast cdc7-related kinases: In vitro phosphorylation of MCM subunits by a putative human homologue of cdc7</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="16"></voliss><pagerange last="4351" first="4340"></pagerange></ref-volisspag></ref-info></reference><reference id="50"><ref-info><ref-title><ref-titletext>Association of RPA with chromosomal replication origins requires an MCM protein, and is regulated by Rad53, and cyclin- and dbf4-dependent kinases</ref-titletext></ref-title><ref-sourcetitle>EMBO J.</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="17"></voliss><pagerange last="5191" first="5182"></pagerange></ref-volisspag></ref-info></reference><reference id="51"><ref-info><ref-title><ref-titletext>DNA replication in vertebrates requires a homolog of the cdc7 protein kinase</ref-titletext></ref-title><ref-sourcetitle>Proc. Natl. Acad. Sci. USA</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="96"></voliss><pagerange last="2804" first="2800"></pagerange></ref-volisspag></ref-info></reference><reference id="52"><ref-info><ref-title><ref-titletext>Regulation of replicon size in Xenopus egg extracts</ref-titletext></ref-title><ref-sourcetitle>Science</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="275"></voliss><pagerange last="995" first="993"></pagerange></ref-volisspag></ref-info></reference><reference id="53"><ref-info><ref-title><ref-titletext>The use of Xenopus laevis interphase egg extracts to study genomic DNA replication</ref-titletext></ref-title><ref-sourcetitle>Eukaryotic DNA Replication: A Practical Approach</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-text>S. Cotterill., ed. (Oxford: Oxford University Press)</ref-text></ref-info></reference><reference id="54"><ref-info><ref-title><ref-titletext>Regulated chromosomal DNA replication in the absence of a nucleus</ref-titletext></ref-title><ref-sourcetitle>Mol. Cell</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="1"></voliss><pagerange last="529" first="519"></pagerange></ref-volisspag></ref-info></reference><reference id="55"><ref-info><ref-title><ref-titletext>DNA topoisomerases</ref-titletext></ref-title><ref-sourcetitle>Annu Rev. Biochem.</ref-sourcetitle><ref-publicationyear first="1985"></ref-publicationyear><ref-volisspag><voliss volume="54"></voliss><pagerange last="697" first="665"></pagerange></ref-volisspag></ref-info></reference><reference id="56"><ref-info><ref-title><ref-titletext>Initiation of simian virus 40 DNA replication in vitro: Large-tumour-antigen- and origin-dependent unwinding of the template</ref-titletext></ref-title><ref-sourcetitle>Proc. Natl. Acad. Sci. USA</ref-sourcetitle><ref-publicationyear first="1987"></ref-publicationyear><ref-volisspag><voliss volume="84"></voliss><pagerange last="3647" first="3643"></pagerange></ref-volisspag></ref-info></reference><reference id="57"><ref-info><ref-title><ref-titletext>Biochemical analysis of the intrinsic Mcm4-Mcm6-Mcm7 DNA helicase activity</ref-titletext></ref-title><ref-sourcetitle>Mol. Cell. Biol.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="19"></voliss><pagerange last="8115" first="8003"></pagerange></ref-volisspag></ref-info></reference><reference id="58"><ref-info><ref-title><ref-titletext>Formation of a pre-initiation complex by S-phase cyclin cdk-dependent loading of Cdc45p onto chromatin</ref-titletext></ref-title><ref-sourcetitle>Science</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="280"></voliss><pagerange last="596" first="593"></pagerange></ref-volisspag></ref-info></reference></bibliography></tail></bibrecord></item><item><ait:process-info><ait:date-delivered year="2010" month="03" day="04"></ait:date-delivered><ait:date-sort year="2000" month="11" day="17"></ait:date-sort><ait:status type="core" state="new" stage="S300"></ait:status></ait:process-info><bibrecord><item-info><copyright type="Elsevier">Copyright 2010 Elsevier B.V., All rights reserved.</copyright><itemidlist><ce:doi>10.1021/jo000814y</ce:doi><itemid idtype="ISSN">00223263</itemid><itemid idtype="CODENCODE">JOCEAH</itemid><itemid idtype="PUI">30992624</itemid><itemid idtype="CHEM">2000073482</itemid><itemid idtype="EMBASE">2000433238</itemid></itemidlist><history><date-created year="2009" month="12" day="06"></date-created></history></item-info><head><citation-info><citation-type code="ar"></citation-type><citation-language xml:lang="eng"></citation-language><abstract-language xml:lang="eng"></abstract-language></citation-info><citation-title><titletext xml:lang="eng" original="y">Poly(3-hydroxybutyrate)-depolymerase from Pseudomonas lemoignei: Catalysis of esterifications in organic media</titletext></citation-title><author-group><author type="AU" seq="1"><ce:initials>A.</ce:initials><ce:indexed-name>Kumar A.</ce:indexed-name><ce:surname>Kumar</ce:surname></author><author type="AU" seq="2"><ce:initials>R.A.</ce:initials><ce:indexed-name>Gross R.A.</ce:indexed-name><ce:surname>Gross</ce:surname></author><author type="AU" seq="3"><ce:initials>D.</ce:initials><ce:indexed-name>Jendrossek D.</ce:indexed-name><ce:surname>Jendrossek</ce:surname></author><affiliation country="usa"><organization>Dept. Chem. Engg., Chem./Mat. Sci., Polytechnic University</organization><city-group>Brooklyn, NY 11201</city-group></affiliation></author-group><correspondence><person><ce:initials>R.A.</ce:initials><ce:indexed-name>Gross R.A.</ce:indexed-name><ce:surname>Gross</ce:surname></person><affiliation country="usa"><organization>Dept. Chem. Engg., Chem./Mat. Sci., Polytechnic University</organization><city-group>Brooklyn, NY 11201</city-group></affiliation><ce:e-address>rgross@poly.edu</ce:e-address></correspondence><abstracts><abstract original="y"><ce:para>Lipase catalysis in nonaqueous media is recognized as a powerful tool in organic and more recently polymer synthesis. Even though none of the currently known polyhydroxyalkanoate (PHA) depolymerases have lipase activity, they do have a catalytic center that resembles that of lipases. Motivated by the above, the potential of using the poly(3-hydroxybutyrate), PHB, depolymerase from Psuedomonas lemoignei in organic media to catalyze ester-forming reactions was investigated. The effect of different organic solvents (benzene-d<inf>6</inf>, cyclohexane-d<inf>12</inf>, and acetonitrile-d<inf>3</inf>) on the activity of the PHB-depolymerase toward propylation of L-lactide was studied. A significant difference in the catalytic rate was observed as a function of solvent polarity. The selectivity of the PHB-depolymerase (P. lemoignei) to catalyze the propylation of a series of different lactones including ε-caprolactone, δ-butyrolactone, γ-butyrolactone, and D, L, meso, and racemic lactides has been studied with the PHB-depolymerase (P. lemoignei) in organic solvents. Important differences in the reactivity of these lactones, as well as selective hydrolysis of stereochemically different linear lactic acid dimers, were observed. Moreover, the ability of the PHB-depolymerase to catalyze the solventless polymerization of ε-caprolactone and trimethylene carbonate was investigated.</ce:para></abstract></abstracts><source type="j" country="usa"><sourcetitle>Medecine et Droit</sourcetitle><sourcetitle-abbrev>Med. Droit</sourcetitle-abbrev><issn type="print">00223263</issn><codencode>JOCEA</codencode><volisspag><voliss volume="65" issue="23"></voliss><pagerange last="7806" first="7800"></pagerange></volisspag><publicationyear first="2000"></publicationyear><publicationdate><year>2000</year><month>11</month><day>17</day></publicationdate><publisher><publishername>American Chemical Society</publishername><ce:e-address>service@acs.org</ce:e-address></publisher><publisher><affiliation><organization>American Chemical Society</organization></affiliation></publisher></source><enhancement><descriptorgroup><descriptors type="DRG" controlled="y"><descriptor><mainterm weight="b" candidate="n">acetonitrile derivative</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">benzene derivative</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">cyclohexane derivative</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">lactic acid derivative</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">lactone derivative</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">organic solvent</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">poly(3 hydroxybutyric acid)</mainterm><link>endogenous compound</link></descriptor><descriptor><mainterm weight="a" candidate="y">poly(3 hydroxybutyric acid) depolymerase</mainterm><link>endogenous compound</link></descriptor><descriptor><mainterm weight="b" candidate="n">polyhydroxyalkanoic acid</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">unclassified drug</mainterm></descriptor></descriptors><descriptors type="MED" controlled="y"><descriptor><mainterm weight="b" candidate="n">article</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">catalysis</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">enzyme activity</mainterm></descriptor><descriptor><mainterm weight="a" candidate="n">esterification</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">hydrolysis</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">nonhuman</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">polymerization</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">Pseudomonas</mainterm></descriptor><descriptor><mainterm weight="b" candidate="y">pseudomonas lemoignei</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">reaction analysis</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">stereochemistry</mainterm></descriptor><descriptor><mainterm weight="b" candidate="n">synthesis</mainterm></descriptor></descriptors></descriptorgroup><classificationgroup><classifications type="ASJC"><classification><classification-code>1605</classification-code></classification></classifications></classificationgroup><chemicalgroup><chemicals source="esbd"><chemical><chemical-name>26063-00-3</chemical-name><cas-registry-number>poly(3 hydroxybutyric acid)</cas-registry-number></chemical></chemicals></chemicalgroup></enhancement></head><tail><bibliography refcount="31"><reference id="1"><ref-info><ref-sourcetitle>Enzyme catalysis in organic synthesis</ref-sourcetitle><ref-publicationyear first="1995"></ref-publicationyear><ref-volisspag><voliss volume="1-2"></voliss></ref-volisspag><ref-text>Drauz, K., Waldmann, H., Eds.; VCH: Weinheim</ref-text></ref-info></reference><reference id="2"><ref-info><ref-sourcetitle>Tetrahedron</ref-sourcetitle><ref-publicationyear first="1989"></ref-publicationyear><ref-volisspag><voliss volume="45"></voliss><pagerange last="7082" first="7077"></pagerange></ref-volisspag></ref-info></reference><reference id="3"><ref-info><ref-sourcetitle>Chem. Lett.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><pagerange last="34" first="33"></pagerange></ref-volisspag></ref-info></reference><reference id="4"><ref-info><ref-sourcetitle>Tetrahedron</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="48"></voliss><pagerange last="9876" first="9869"></pagerange></ref-volisspag></ref-info></reference><reference id="5"><ref-info><ref-sourcetitle>Tetrahedron: Asymmetry</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="4"></voliss><pagerange last="760" first="757"></pagerange></ref-volisspag></ref-info></reference><reference id="6"><ref-info><ref-sourcetitle>Pure Appl. Chem.</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="64"></voliss><pagerange last="1170" first="1165"></pagerange></ref-volisspag></ref-info></reference><reference id="7"><ref-info><ref-sourcetitle>Acc. Chem. Res.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="23"></voliss><pagerange last="120" first="114"></pagerange></ref-volisspag></ref-info></reference><reference id="8"><ref-info><ref-sourcetitle>Tetrahedron</ref-sourcetitle><ref-publicationyear first="1997"></ref-publicationyear><ref-volisspag><voliss volume="53"></voliss><pagerange last="2176" first="2163"></pagerange></ref-volisspag></ref-info></reference><reference id="9"><ref-info><ref-sourcetitle>Microbiol. Rev.</ref-sourcetitle><ref-publicationyear first="1990"></ref-publicationyear><ref-volisspag><voliss volume="54"></voliss><pagerange last="472" first="450"></pagerange></ref-volisspag></ref-info></reference><reference id="10"><ref-info><ref-sourcetitle>Microbiol. Mol. Rev.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="63"></voliss><pagerange last="53" first="21"></pagerange></ref-volisspag></ref-info></reference><reference id="11"><ref-info><ref-sourcetitle>Appl. Microbiol. Biotechnol.</ref-sourcetitle><ref-publicationyear first="1996"></ref-publicationyear><ref-volisspag><voliss volume="46"></voliss><pagerange last="463" first="451"></pagerange></ref-volisspag></ref-info></reference><reference id="12"><ref-info><ref-sourcetitle>Polym. Degrad. Stab.</ref-sourcetitle><ref-publicationyear first="1998"></ref-publicationyear><ref-volisspag><voliss volume="59"></voliss><pagerange last="325" first="317"></pagerange></ref-volisspag></ref-info></reference><reference id="13"><ref-info><ref-sourcetitle>Appl. Environm Microbiol.</ref-sourcetitle><ref-publicationyear first="1995"></ref-publicationyear><ref-volisspag><voliss volume="61"></voliss><pagerange last="3118" first="3113"></pagerange></ref-volisspag></ref-info></reference><reference id="14"><ref-info><ref-sourcetitle>J. Am. Chem. Soc.</ref-sourcetitle><ref-publicationyear first="1988"></ref-publicationyear><ref-volisspag><voliss volume="110"></voliss><pagerange last="7237" first="7236"></pagerange></ref-volisspag></ref-info></reference><reference id="15"><ref-info><ref-sourcetitle>J. Am. Chem. Soc.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="115"></voliss><pagerange last="396" first="390"></pagerange></ref-volisspag></ref-info></reference><reference id="16"><ref-info><ref-sourcetitle>Bioorg. Med. Chem. Lett.</ref-sourcetitle><ref-publicationyear first="1991"></ref-publicationyear><ref-volisspag><voliss volume="1"></voliss><pagerange last="405" first="399"></pagerange></ref-volisspag></ref-info></reference><reference id="17"><ref-info><ref-sourcetitle>J. Am. Chem. Soc.</ref-sourcetitle><ref-publicationyear first="1992"></ref-publicationyear><ref-volisspag><voliss volume="114"></voliss><pagerange last="1884" first="1882"></pagerange></ref-volisspag></ref-info></reference><reference id="18"><ref-info><ref-sourcetitle>J. Bacteriol.</ref-sourcetitle><ref-publicationyear first="1974"></ref-publicationyear><ref-volisspag><voliss volume="119"></voliss><pagerange last="161" first="152"></pagerange></ref-volisspag></ref-info></reference><reference id="19"><ref-info><ref-sourcetitle>Appl. Environm. Microbiol.</ref-sourcetitle><ref-publicationyear first="1999"></ref-publicationyear><ref-volisspag><voliss volume="65"></voliss><pagerange last="1709" first="1703"></pagerange></ref-volisspag></ref-info></reference><reference id="20"><ref-info><ref-sourcetitle>Eur. J. Biochem.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="218"></voliss><pagerange last="710" first="701"></pagerange></ref-volisspag></ref-info></reference><reference id="21"><ref-info><ref-sourcetitle>J. Environm. Polym. Degrad.</ref-sourcetitle><ref-publicationyear first="1993"></ref-publicationyear><ref-volisspag><voliss volume="1"></voliss><pagerange last="63" first="53"></pagerange></ref-volisspag></ref-info></reference><reference id="22"><ref-info><ref-publicationyear first="1987"></ref-publicationyear><ref-volisspag><voliss volume="17"></voliss><pagerange last="126" first="7"></pagerange></ref-volisspag><ref-text>Stereochemistry of Organic and Bioorganic Transformations; Bartmann, W., Sharpless, K. B., Eds.; VCH: Weinheim, West Germany</ref-text></ref-info></reference><reference id="23"><ref-info><

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