title: Daily rhythmicity of clock gene transcript levels in fast and slow muscle fibers from Chinese perch (Siniperca chuatsi).
abstract: Clock genes are considered to be the molecular core of biological clock in vertebrates and they are directly involved in the regulation of daily rhythms in vertebrate tissues such as skeletal muscles. Fish myotomes are composed of anatomically segregated fast and slow muscle fibers that possess different metabolic and contractile properties. To date, there is no report on the characterization of the circadian clock system components of slow muscles in fish.
  
  
  
  In the present study, the molecular clock components (clock, arntl1/2, cry1/2/3, cry-dash, npas2, nr1d1/2, per1/2/3, rorα and tim genes) and their daily transcription levels were characterized in slow and fast muscles of Chinese perch (Siniperca chuatsi). Among the 15 clock genes, nrld2 and per3 had no daily rhythmicity in slow muscles, and cry2/3 and tim displayed no daily rhythmicity in fast muscles of the adult fish. In the slow muscles, the highest expression of the most clock paralogs occurred at the dark period except arntl1, nr1d1, nr1d2 and tim. With the exception of nr1d2 and tim, the other clock genes had an acrophase at the light period in fast muscles. The circadian expression of the myogenic regulatory factors (mrf4 and myf5), mstn and pnca showed either a positive or a negative correlation with the transcription pattern of the clock genes in both types of muscles.
  
  
  
  It was the first report to unravel the molecular clock components of the slow and fast muscles in vertebrates. The expressional pattern differences of the clock genes between the two types of muscle fibers suggest that the clock system may play key roles on muscle type-specific tissue maintenance and function.
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China.
authors.forename: Yu-Long
authors.initials: YL
authors.lastname: Li
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhu
authors.affiliation: College of Life Sciences, Xinyang Normal University, Xinyang, Henan, 464000, China.
authors.forename: Zhi-Guo
authors.initials: ZG
authors.lastname: Feng
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China. jzhang@ccsu.edu.cn.|Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde, 415000, China. jzhang@ccsu.edu.cn.
authors.forename: Jian-She
authors.initials: JS
authors.lastname: Zhang
authors.affiliation: Department of Bioengineering and Environmental Science, Changsha University, Changsha, Hunan, 410003, China. chuwuying18@163.com.|Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde, 415000, China. chuwuying18@163.com.
authors.forename: Wu-Ying
authors.initials: WY
authors.lastname: Chu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D056926:CLOCK Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002681:China; D002940:Circadian Rhythm / Q000235:genetics* / Q000502:physiology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010471:Perches / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D018797:Cell Cycle Proteins; D029941:Fish Proteins; D018006:Myogenic Regulatory Factors; D056926:CLOCK Proteins
keywords: Chinese perch; Clock genes; Daily rhythmicity; Myogenic regulatory factors; Skeletal muscle