title: Embryonic temperature and the relative timing of muscle-specific genes during development in herring (Clupea harengus L.).
abstract: Temperature influences many aspects of muscle development in herring (Clupea harengus). In Clyde herring, myofibril synthesis occurred later with respect to somite stage in embryos reared at 5 degrees C compared with 12 degrees C. The aim of the present study was to test the hypothesis that the relative timing of expression of myogenic regulatory factors (MRFs) and myosin heavy chain (MyHC) transcripts changes with developmental temperature. Reverse transcriptase/polymerase chain reaction (RT-PCR) was used to clone partial coding regions of MyoD, myogenin and MyHC from juvenile Clyde herring. Embryos were reared at 5, 8 and 12 degrees C, and the spatial and temporal expression patterns of transcripts were investigated using cRNA probes and in situ hybridisation. Antisense probes revealed a rostral-caudal progression of all three transcripts. MyoD transcription initially took place in the adaxial cells of the unsegmented, presomitic mesoderm, whereas myogenin transcription first occurred in newly formed somites. The MyHC gene transcript was not detected until approximately nine somites had formed. Since the somite stage at which the MRFs and MyHC were first expressed was independent of temperature, the hypothesis was rejected. We suggest that the effects of temperature on myofibril synthesis must occur downstream from MyHC transcription either at the level of translation or at the assembly stage.
authors.affiliation: Gatty Marine Laboratory, Division of Environmental and Evolutionary Biology, School of Biology, University of St Andrews, St Andrews, Fife KY16 8LB, Scotland. gkt@st-and.ac.uk
authors.forename: G K
authors.initials: GK
authors.lastname: Temple
authors.forename: N J
authors.initials: NJ
authors.lastname: Cole
authors.forename: I A
authors.initials: IA
authors.lastname: Johnston
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005399:Fishes / Q000196:embryology*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D009132:Muscles / Q000196:embryology*; D017570:MyoD Protein / Q000737:chemistry / Q000235:genetics; D018008:Myogenin / Q000737:chemistry / Q000235:genetics; D018995:Myosin Heavy Chains / Q000235:genetics; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D009124:Muscle Proteins; D017570:MyoD Protein; D018008:Myogenin; D015347:RNA Probes; D012333:RNA, Messenger; D018995:Myosin Heavy Chains