EMBRYONIC EXPRESSION OF MUSCLE-SPECIFIC ANTIGENS IN THE GRASSHOPPER SCHISTOCERCA-GREGARIA

Monoclonal antibodies (MAbs) are used to investigate molecules that ar e expressed during embryonic muscle differentiation and that may be in volved in muscle pioneer and muscle attachment site formation. MAb F2A 5 immunoreactivity appears in all muscle pioneers as soon as they exte nd processes, and continues in all muscle precursors. MAb 4H1 immunore activity is strongly expressed only after mesodermal cells have fused with the muscle pioneers; then it is concentrated at their growth-cone -like ends near developing attachment sites. During later embryonic de velopment, MAb F2A5 and MAb 4H1 immunoreactivity become associated wit h the myofibrillar network. Biochemical experiments indicate that MAb 4H1 recognises a 47 kDa antigen, and MAb F2A5 recognises an 80 kDa ant igen.