title: Temperature-dependent developmental variation in lobster muscle myosin heavy chain isoforms.
abstract: The temperature- and developmental-regulation of myosin heavy chain (MyHC) expression and primary sequence was investigated in the abdominal musculature of developing Homarus gammarus larvae acclimated to 10, 14 and 19+/-1 degrees C. MyHC loop 1 (ATP binding) and loop 2 (actin binding) regions were sequenced and compared. The deduced amino acid sequence of MyHC loop 1 showed a development-related increase in net charge from +1 to +2 between larval stages 1 and 2, which was not temperature-dependent. In post-settled stage 9 larvae, minor shifts in amino acid sequence occurred at 19 degrees C, and corresponded to a significant up-regulation of fast myosin mRNA expression. However, no temperature-specific loop 1 isoforms were detected. The deduced amino acid sequence of MyHC loop 2 was not affected by temperature, and the net charge remained +4 throughout development. These findings contrast to previous studies using the common carp, in which temperature-specific MyHC isoform genes were expressed in response to disparate thermal regimes. This raises the question as to whether arthropods do not express specific temperature isoforms but instead rely on shifts in fibre type to accommodate alterations in thermal environment.
authors.affiliation: Center for Science and Technology in Medicine, School of Postgraduate Medicine, Keele University, North Staffordshire Hospital, Thornburrow Road, Hartshill, Stroke-on-Trent ST4 7QB, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Magnay
authors.forename: J M
authors.initials: JM
authors.lastname: Holmes
authors.forename: D M
authors.initials: DM
authors.lastname: Neil
authors.forename: A J
authors.initials: AJ
authors.lastname: El Haj
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D007814:Larva / Q000235:genetics / Q000254:growth & development; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics*; D008121:Nephropidae / Q000235:genetics* / Q000254:growth & development; D020033:Protein Isoforms / Q000235:genetics; D012313:RNA / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D018076:DNA, Complementary; D020033:Protein Isoforms; D012313:RNA; D018995:Myosin Heavy Chains