Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Aquaculture
In penaeoidean shrimp the larval muscle has two origins: (1) the naupliar mesoderm forms the musculature of the first and second antennae and mandibles, and (2) the teloblastic mesoderm forms the muscle of the posterior limbs and trunk. The development of larval muscles was examined by staining with fluorescent phallotoxins and confocal microscopy. Foci of muscle fiber formation were first detected in embryonic limb buds of Sicyonia ingentis at about 50% time to hatching. These muscle fibers developed into the extrinsic limb muscles of the nauplius, which enlarged during later naupliar instars. Visceral muscle formation occurred during the development of the gut during nauplius stages 4 and 5. Muscle development in later larval stages was examined in Litopenaeus vannemei. The major thoraco-abdominal trunk muscles, including dorsal abdominal muscles (extensors), oblique muscles (flexors) and transverse muscles (stators), were formed by the mysis stages. Thoracic and abdominal limb muscles developed shortly before these limbs became functional for locomotion in mysis and postlarval stages. Postlarvae contained the muscles present in the adult, and could be compared to the adult muscle anatomy described for Penaeus setiferus (Young, J.H. 1959. Fishery Bulletin 59:1-168). The detailed description of larval muscle development should be useful in the analysis of shrimp strains developed for faster growth. We are also targeting genes required for mesoderm and muscle development in shrimp by degenerate PCR. The identification of genes that control muscle development should provide additional avenues for the improvement of muscle growth in shrimp.