title: [Expression profile of clock genes during the process of embryonic stem cells differentiation].
abstract: OBJECTIVE
  To analysis the expression profile of7 clock genes during mouse embryonic stem cell (mES) differentiation.
  
  
  METHODS
  Mouse ES cells of the line 129 were cultured and induced to differentiate into neurons by 5 stages method. The expression of 7 clock genes: BMAL1, CLOCK, CRY1, CRY2, PER1, PER2, and PER3 in the five stages were determined by RT-PCR.
  
  
  RESULTS
  In the amplification condition, no non-specific band was found, and only bands of expected sizes were detected. Six clock genes, BMAL1, CLOCK, CRY1, CRY2, PER1 and PER3 were expressed in 129 cells at all five stages in the differentiation process, however, PER2, could only be determined in the last stage.
  
  
  CONCLUSIONS
  The transcription profile of the clock genes is different during the differentiation of the ES cells towards neurons. The transcription of the gene PER2 is limited to the final stage, when postmitotic neurons and astrocytes emerged. A clock genes loop existing in the mature cells has not been established during the process of ES cell differentiation.
authors.affiliation: Department of Neurobiology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Xie
authors.forename: Yan-ning
authors.initials: YN
authors.lastname: Cai
authors.forename: Yun-qian
authors.initials: YQ
authors.lastname: Guan
authors.forename: Wen-qi
authors.initials: WQ
authors.lastname: Wu
authors.forename: Yan-ling
authors.initials: YL
authors.lastname: Xu
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Biao
authors.initials: B
authors.lastname: Chen
mesh_terms: D000818:Animals; D056926:CLOCK Proteins; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D015534:Trans-Activators; D056926:CLOCK Proteins; C538944:Clock protein, mouse