<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>M.C. Gomez</dc:contributor>
  <dc:contributor>J.A. Jenkins</dc:contributor>
  <dc:contributor>S.P. Leibo</dc:contributor>
  <dc:contributor>G. Wirtu</dc:contributor>
  <dc:contributor>B.L. Dresser</dc:contributor>
  <dc:contributor>C.E. Pope</dc:contributor>
  <dc:creator>L. Chacon</dc:creator>
  <dc:date>2009</dc:date>
  <dc:description>&lt;p&gt;&lt;span data-mce-bogus="1" data-mce-type="format-caret"&gt;&lt;/span&gt;&lt;/p&gt;&lt;div class="row"&gt;&lt;div class="large-10 medium-10 small-12 columns"&gt;&lt;div class="description"&gt;&lt;div class="abstract" data-abstract-type="normal"&gt;&lt;p&gt;Usually, fibroblasts are frozen in dimethyl sulphoxide (DMSO, 10% v/v) at a cooling rate of 1 °C/min in a low-temperature (−80 °C) freezer (LTF) before storage in liquid nitrogen (LN&lt;span class="sub"&gt;2&lt;/span&gt;); however, a LTF is not always available. The purpose of the present study was to evaluate apoptosis and viability of bovine fibroblasts frozen in a LTF or conventional freezer (CF; −20 °C) and their subsequent ability for development to blastocyst stage after fusion with enucleated bovine oocytes. Percentages of live cells frozen in LTF (49.5%) and CF (50.6%) were similar, but significantly less than non-frozen control (88%). In both CF and LTF, percentages of live apoptotic cells exposed to LN&lt;span class="sub"&gt;2&lt;/span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;after freezing were lower (4% and 5%, respectively) as compared with unexposed cells (10% and 18%, respectively). Cells frozen in a CF had fewer cell doublings/24 h (0.45) and required more days (9.1) to reach 100% confluence at the first passage (P) after thawing and plating as compared with cells frozen in a LTF (0.96 and 4.0 days, respectively). Hypoploidy at P12 was higher than at P4 in cells frozen in either a CF (37.5% vs. 19.2%) or in a LTF (30.0% vs. 15.4%). A second-generation cryo-solution reduced the incidence of necrosis (29.4%) at 0 h after thawing as compared with that of a first generation cryo-solution (DMEM + DMSO, 60.2%). The percentage of apoptosis in live cells was affected by cooling rate (CF = 1.9% vs. LFT = 0.7%). Development of bovine cloned embryos to the blastocyst stage was not affected by cooling rate or freezer type.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1017/S0967199409005474</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Cambridge University Press</dc:publisher>
  <dc:title>Production of bovine cloned embryos with donor cells frozen at a slow cooling rate in a conventional freezer (20 C)</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>