Vesicle trafficking during wing margin development: a role for Docked. Suresh K. Kandasamy, Justin Thackeray. Biology Dept, Clark University, Worcester, MA.

   We show that the previously described gene docked (doc) corresponds to the gene model CG5484. The gene encodes a homolog of yeast Yif1, which is known to play a key role in transport of vesicles between the ER and Golgi. A viable allele, doc¹, shows a truncated wing phenotype very similar to that seen in the "oblique" class of dumpy (dp) alleles, and we find that there is a synergistic interaction between alleles of doc and dp. We observed genetic interactions between doc alleles and those of genes encoding the COPII vesicle components Sec13, Sec23 and Sar1, as well as the SNARE protein Syntaxin1A, strongly suggesting a role for Doc in trafficking of COPII vesicles. Loss of Doc function in the wing margin using a UAS-RNAi construct produced wing nicks; this nicking is rescued by over-expression of Serrate or Delta, suggesting that the nicks are due to reduced trafficking of these transmembrane ligands. We also investigated whether the oblique wing phenotype observed in doc¹ flies is due to reduced trafficking of Dumpy; we found that the wing phenotype seen in dp^D heterozygotes is indeed enhanced by several of the same vesicle trafficking mutants described above that interact with doc. It remains unclear why the oblique wing phenotype is the only visible defect observed in doc¹. One possible explanation we pursued is that this is because Dp is so large (estimated at 2.5MDa) it is especially sensitive to reduced efficiency in vesicle trafficking. However, we could observe no interaction between doc¹ and alleles of several other genes encoding very large proteins, such as sallimus and mucin14A.