title: Cloning of cDNAs for H1F0, TOP1, CLTA and CDK1 and the effects of cryopreservation on the expression of their mRNA transcripts in yak (Bos grunniens) oocytes.
abstract: BACKGROUND
  We cloned and sequenced four pivotal cDNAs involved in DNA structural maintenance (H1F0 and TOP1) and the cell cycle (CLTA and CDK1) from yak oocytes. In addition, we studied the consequences of freezing-thawing (F/T) processes on the expression of their mRNA transcripts in yak immature and in vitro matured (MII) oocytes.
  
  
  METHODS
  H1F0, TOP1, CLTA and CDK1 cDNAs were cloned from yak oocytes by reverse transcriptase-polymerase chain reaction (RT-PCR) strategy. The expression of their mRNA transcript analyses were performed upon fresh and frozen-thawed immature germinal vesicle (GV) and MII yak oocytes following normalization of transcripts with GAPDH by real-time PCR.
  
  
  RESULTS
  The yak H1F0, TOP1, CLTA and CDK1 cDNA sequences were found to consist of CDK1 585, 2539, 740, and 894 bp, respectively. Their coding regions encoded 195, 768, 244, and 298 amino acids, respectively. The homology with that of cattle was very high (95.2%, 98.8%, 93.6%, and 89.5%, respectively nucleotide sequence level, and 94.3%, 98.2%, 87.7%, and 90.9%, respectively at the deduced amino acid level). The overall mRNA expression levels of these four transcripts were reduced by F/T process, albeit at different levels. TOP1 in GV-oocytes, and H1F0 and CDK1 in MII-oocytes of the yak were significantly down-regulated (P<0.05).
  
  
  CONCLUSIONS
  This is the first isolation and characterization of H1F0, TOP1, CLTA, and CDK1 cDNAs from yak oocytes. The lower fertility and developmental ability of yak oocytes following fertilization after cryopreservation may be explained by the alterations to their gene expression profiles.
authors.affiliation: College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Hui-Ran
authors.initials: HR
authors.lastname: Niu
authors.affiliation: College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, PR China. Electronic address: zixd2000@yahoo.com.
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Zi
authors.affiliation: College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.affiliation: College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Xian-Rong
authors.initials: XR
authors.lastname: Xiong
authors.affiliation: College of Tibetan Plateau Research, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Jin-Cheng
authors.initials: JC
authors.lastname: Zhong
authors.affiliation: College of Tibetan Plateau Research, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Tibetan Plateau Research, Southwest University for Nationalities, Chengdu 610041, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics*; D002417:Cattle; D033922:Clathrin Heavy Chains / Q000235:genetics*; D003001:Cloning, Molecular; D015925:Cryopreservation; D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D005298:Fertility; D005306:Fertilization; D005615:Freezing / Q000009:adverse effects; D006657:Histones / Q000235:genetics*; D009865:Oocytes / Q000166:cytology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; D006657:Histones; D012333:RNA, Messenger; D033922:Clathrin Heavy Chains; D016203:CDC2 Protein Kinase; D004264:DNA Topoisomerases, Type I
keywords: Cloning; Cryopreservation; Oocytes; Real-time PCR; Yak