Fertilization typically involves membrane fusion between sperm and eggs. In Drosophila, however, sperm enter eggs with membranes intact. Consequently, sperm plasma membrane breakdown (PMBD) and subsequent events of sperm activation occur in the egg cytoplasm. We previously proposed that mutations in the sneaky (snky) gene result in male sterility due to failure in PMBD. Here we support this proposal by demonstrating persistence of a plasma membrane protein around the head of snky sperm after entry into the egg. We further show that snky is expressed in testes and encodes a predicted integral membrane protein with multiple transmembrane domains, a DC-STAMP-like domain, and a variant RING finger. Using a transgene that expresses an active Snky-Green fluorescent protein fusion (Snky-GFP), we show that the protein is localized to the acrosome, a membrane-bound vesicle located at the apical tip of sperm. Snky-GFP also allowed us to follow the fate of the protein and the acrosome during fertilization. In many animals, the acrosome is a secretory vesicle with exocytosis essential for sperm penetration through the egg coats. Surprisingly, we find that the Drosophila acrosome is a paternally inherited structure. We provide evidence that the acrosome induces changes in sperm plasma membrane, exclusive of exocytosis and through the action of the acrosomal membrane protein Snky. Existence of testis-expressed Snky-like genes in many animals, including humans, suggests conserved protein function. We relate the characteristics of Drosophila Snky, acrosome function and sperm PMBD to membrane fusion events that occur in other systems.

Background: The purpose of this study was to identify the utilization rate and most common reasons for presentation to the emergency department (ED) after elective outpatient hand surgery and to determine preoperative risk factors for these ED visits. Methods: Patients who underwent elective hand surgery at an ambulatory surgery center between 2014 and 2015 were retrospectively evaluated using the New York and Florida State Databases. The primary outcome was all-cause 7- and 30-day ED utilization rates. Reasons for presentation to the ED were recorded and manually stratified. Bivariate and multivariate analyses were performed to identify independent predictors of ED utilization. Results: From 2014 to 2015, 212,506 procedures were identified; the 7- and 30-day ED visit rates were 1.8% and 4.4%, respectively. Postoperative pain was the most common cause of an ED visit after outpatient hand surgery at 7 days (25.4%) and 30 days (16.1%) postoperatively. Overall, 98% of patients presenting to the ED for postoperative pain were subsequently discharged home. After controlling for confounding, comorbid congestive heart failure, chronic lung disease, diabetes, renal failure, schizophrenia, and depression were independent risk factors for an ED visit at up to 30 days postoperatively. Those with Medicare insurance were 94% more likely to present to the ED within 30 days than those with private health insurance, whereas those with Medicaid were more than three times as likely to present to the ED as those with private insurance. Discussion: ED utilization after outpatient hand surgery is low, with postoperative pain being the most common cause of an ED visit at all time points. Nearly 98% of patients presenting to the ED for postoperative pain are subsequently discharged home. Level of Evidence: Level III, Retrospective Cohort

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