ANTIBODY BLOCK OF A NEURAL-TISSUE-SPECIFIC GLYCOCONJUGATE PERTURBS GROWTH CONE GUIDANCE OF AN IDENTIFIED INTERNEURON IN THE GRASSHOPPER

Antibodies against horseradish peroxidase (HRP) recognize a neural-tis sue-specific carbohydrate moiety that is expressed on a complex set of developmentally regulated antigens in grasshopper, Drosophila and oth er insects. The functional role of the neural-specific carbohydrate ha s been investigated by mutant analysis in Drosophila where subtle defe cts in wing sensory axon projections have been reported. Here we exten d the analysis of this neural-specific carbohydrate to the single cell level by focusing on identified brain interneurons in the grasshopper embryo. Immunological blocking experiments carried out in embryo cult ure show that the neural-specific carbohydrate is essential for correc t axonal guidance of the identified interneurons. Functional block of the carbohydrate epitope causes major aberrations in growth cone guida nce and axonal outgrowth in approximately 40% of the cases studied. Th is analysis reveals an important role of neural-specific glycoconjugat e for correct axonal guidance of individual identified neurons.