CELL-SPECIFIC, TISSUE-SPECIFIC, AND POSITION-SPECIFIC MONOCLONAL-ANTIBODIES AGAINST THE PLANARIAN DUGESIA (GIRARDIA) TIGRINA

To obtain specific immunological probes for studying molecular mechani sms involved in cell renewal, cell differentiation, and pattern format ion in intact and regenerating planarians, we have produced a hybridom a library specific for the asexual race of the freshwater planarian Du gesia (Girardia) tigrina. Among the 276 monoclonal antibodies showing tissue-, cell-, cell subtype-, subcellular- and position-specific stai ning, we have found monoclonal antibodies against all tissues and cell types with the exception of neoblasts, the undifferentiated totipoten t stem-cells in planarians. We have also detected position-specific an tigens that label anterior, central, and posterior regions. Patterns o f expression uncovered an unexpected heterogeneity among previously th ought single cell types, as well as interesting cross-reactivities tha t deserve further study. Characterization of some of these monoclonal antibodies suggests they may be extremely useful as molecular markers for studying cell renewal and cell differentiation in the intact and r egenerating organism, tracing the origin, lineage, and differentiation of blastema cells, and characterizing the stages and mechanisms of ea rly pattern formation. Moreover, two position-specific monoclonals, th e first ones isolated in planarians, will be instrumental in describin g in molecular terms how the new pattern unfolds during regeneration a nd in devising the pattern formation model that best fits classical da ta on regeneration in planarians.