• Main Authors: Nádia Silva, Vitor M. Baptista, Deborah M. Power
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Key Words; Flatfish; in situ localisation; muscle development; thyroid hormones; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.617.4878; http://arch-anim-breed.fbn-dummerstorf.de/pdf/2006/at06si1p097.pdf

Expression patterns of MLC isoforms during halibut (Hippoglossus hippoglossus L.) metamorphosis Atlantic halibut is an important commercial fish in the countries of the North Atlantic and is emerging as a promising species for marine cold-water aquaculture. The axial musculature of the developing larvae is the largest and most rapidly growing tissue and during the transition from larval to adult muscle fibre types significant changes in fibre morphology and gene transcription occur. In fact the change in myotome height correlates well with different larval halibut stages. In the present study the spatial and temporal expression of myosin light chain 1 (MLC1), 2 (MLC2) and 3 (MLC3) was studied in metamorphosing halibut by in situ hybridization. As a first step to establishing a role for the thyroid axis in halibut muscle development whole body thyroid hormone (TH) concentrations were also determined. In first feeding larvae MLC1, MLC2A and MLC3 transcripts had a similar distribution and were confined to the muscle fibres of the germinal zones. In pre-metamorphic larvae transcripts were highly expressed throughout the epaxial and hypaxial musculature and expression levels reached a maximum in larvae starting metamorphosis, this change coincided with a significant increase in the concentration of thyroid hormones. By the time larvae reached the metamorphic climax, MLC1, MLC2A and MLC3 expression was still high throughout the musculature but expression was confined to fibres adjacent to the myosepts and to small cells scattered in the musculature, possibly satellite cells. MLC2A was also expressed in the red muscle fibres; no transition between larval and adult MLC isoforms was detected.