Worm Breeder's Gazette 11(3): 49
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
unc-86 mutations affect the cell identities of specific neurons and neuroblasts. To investigate how the gene acts at the molecular and cellular levels, we made antibodies to the unc-86 protein. In brief. we made a full-length cDNA clone using PCR, expressed it in E. coli, purified the protein, and immunized rabbits. Affinity-purified sera stain nuclei in wild-type animals but not in unc-86 deletion mutants. The antisera stain the nuclei of 47 neurons in a newly-hatched L1 and 57 neurons in adults. Most of these neurons have been identified at least tentatively. The anterior nerve ring identifications are by Cori Bargmann. All of the cells that are known to be affected by unc- 86 stain, with the exception of SDQR/L (see below). [See Figure 1] As shown below, in unc-86 mutants the QR and QL lineages are transformed such that one daughter, Q.p, seems to have the same identity as its mother instead of its normal identity. We have investigated where and when in the Q lineages unc-86 protein is expressed. We first see unc-86 protein in QX.p; the staining is unclear but becomes cytoplasmic during mitoses. The protein is distributed to the descendents of QX.p. QX.pp dies, still containing unc-86 protein; in ced-3 animals, there is an extra staining nucleus where the cell death survivor should be. One cell, AVM/PVM, continues to contain unc-86 protein in its nucleus into adulthood. The third cell, SDQR/L, contains unc-86 protein at birth but quickly degrades it. Unexpectedly, a descendent of QX.a, AQR/PQR, begins to express unc- 86 protein even though none of its ancestors did. These data and similar data for the post-dereid neuroblast suggest that in lineages the expression of unc-86 protein in certain daughter cells alters what would otherwise be a stem-cell-like lineage by making the cell identity of that daughter different from the cell identity of the mother. Models in which unc-86 acts non-autonomously or in which the mother/daughter asymmetry results from segregation of the unc-86 protein at cell divisions are now considered unlikely. [See Figure 2]