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Temperature-dependent developmental variation in lobster muscle myosin heavy chain isoforms
J L Magnay1, J M Holmes, D M Neil
1Center for Science and Technology in Medicine, School of Postgraduate Medicine, Keele University, North Staffordshire Hospital, Thornburrow Road, Hartshill, Stroke-on-Trent ST4 7QB, UK.
Gene
|October 18, 2003
Summary
Homarus gammarus larvae myosin heavy chain (MyHC) expression is regulated by development, not temperature. Unlike fish, these crustaceans may adjust muscle function by changing fiber types rather than MyHC isoforms.
Area of Science:
- Marine Biology
- Molecular Biology
- Crustacean Physiology
Background:
- Myosin heavy chain (MyHC) is crucial for muscle contraction.
- MyHC expression and sequence can vary with development and environmental factors like temperature.
- Understanding these variations is key to comprehending muscle adaptation in marine invertebrates.
Purpose of the Study:
- To investigate the temperature and developmental regulation of MyHC expression and primary sequence in Homarus gammarus larvae.
- To compare MyHC loop 1 (ATP binding) and loop 2 (actin binding) sequences across different temperatures and developmental stages.
- To determine if Homarus gammarus expresses temperature-specific MyHC isoforms, contrasting with findings in fish.
Main Methods:
- Larval Homarus gammarus were acclimated to three different temperatures (10, 14, and 19°C).
- MyHC loop 1 and loop 2 regions were sequenced to deduce amino acid sequences.
- MyHC mRNA expression levels were analyzed, particularly for fast myosin.
Main Results:
- MyHC loop 1 showed a development-dependent increase in net charge (+1 to +2) but was not temperature-dependent.
- Minor amino acid sequence shifts in MyHC loop 1 occurred at 19°C in later larval stages, correlating with increased fast myosin mRNA.
- No temperature-specific MyHC loop 1 isoforms were detected, and MyHC loop 2 sequences remained constant across temperatures.
Conclusions:
- Homarus gammarus MyHC expression is primarily regulated by development, with limited temperature influence on primary sequence.
- Arthropods may utilize shifts in muscle fiber type, rather than temperature-specific MyHC isoforms, to adapt to thermal changes.
- This contrasts with fish, which exhibit distinct temperature-dependent MyHC isoforms.