UC San Diego

Spon-1 and pxn-2 are essential basement membrane genes crucial to the elongation stage of C. elegans morphogenesis. However, the interactions of these proteins with other components of the basement membrane and the extracellular matrix are not very well known. In attempts to find factors that interact with spon-1 and pxn-2, EMS screens of both mutants were performed. A suppressor of spon-1 mutants, ju1185, was isolated from the spon-1 screen. We mapped this suppressor to chromosome II between -0.46 and +6.80 using two-point mapping with SNPs. Our rescue experiments suggests that this is a missense mutation in srap-1. We found that overexpression of this gene also suppresses spon-1 suggesting that this may be a gain-of-function mutation. In the pxn-2 mutant screen, a previously isolated suppressor ju1123 rescued embryonic and larval lethality, but has reduced locomotion due to defects in the synaptic release of acetylcholine. In initial observations of the mutant and suppressor nerve cords of C. elegans, we observed an abnormal separation of the dorsal nerve cord axon bundle and GABAergic synapses in commissures. With these observations, we hope to find the relationship between the separations of the nerve cord to pxn-2’s role in synaptic vesicle release. These results can potentially reveal additional roles played by these basement membrane genes, as well as discover additional genes essential in morphogenesis, applicable to the study of the epithelia in vertebrates.