PgmNr D1179: Analyzing the role of the aghino gene in protein and vesicular trafficking during acrosome biogenesis in Drosophila melanogaster.

Authors:
I. Paz 1 ; H. Park 2 ; N. Rigler 2 ; B. Wakimoto 2


Institutes
1) Heritage University, Toppenish, WA; 2) University of Washington, Seattle, WA.


Keyword: spermatogenesis

Abstract:

The aghino (agho) gene was initially defined by a single male sterile mutation. Previously, we reported that agho is one of several genes required for sperm activation during fertilization.  Here we show that agho is the earliest acting of five known genes in the sperm activation pathway. Analysis of new agho alleles recovered by reverse genetics showed that two mutations resulted in defects in biogenesis of the acrosome, a Golgi-derived organelle that is normally localized to the apical tip of mature sperm.  We found that in agho mutants, sperm lacked acrosomes, but entered the egg efficiently then failed to undergo sperm plasma membrane breakdown, an event required to complete fertilization and initiate embryogenesis.  Using a transgene expressing an Agho-Green Fluorescent Protein fusion, we detected the protein at the Trans-Golgi Network, the region of the Golgi that sorts and packages membrane and secreted proteins into vesicles for transport to post-Golgi destinations. Based on these observations, we propose that Agho acts in spermatids to regulate acrosomal protein and vesicular trafficking. We are currently asking whether Agho influences trafficking of non-acrosomal cargos in spermatids. Because Agho is widely expressed, we are also investigating whether mutations affect trafficking in other cell types.  In addition to elucidating the steps required for acrosome formation and function, our results should define Agho’s normal function in both Drosophila germ line and somatic cells.