Real time observation of acrosomal reaction in human sperm

ZOPPINO FCM, HALÓN ND Y MAYORGA LS.

Mendoza

Congreso; Sociedad de Biología de Cuyo; 2010

Sociedad Biología de Cuyo

Acrosomal reaction is a unique event in the sperm life. It consists in the exocytosis of the acrosomal content. This exocytic process is absolutely necessary for egg fertilization. Several methods had been developed to determine the acrosomal reaction but there are only a few real time reports of this process. Here we have used two fluorescent markers to detect acrosomal reaction in real time by confocal microscopy. Human sperm cells were capacitated during 3 hours. Fluorescein isothiocyanate (FITC) labeled Soybean Trypsin Inhibitor (SBTI-FITC) with affinity for the acrosomal hydrolase acrosin or Pisum sativum Agglutinin (PSA-FTC) with preference for glycoconjugates of acrosomal matrix were added to the medium. The acrosomal reaction was induced with 0,010 mM of calcium ionophore A23187. The opening of fusion pores was detected as an increased of fluorescence in the acrosomal region. Both markers were useful to observe AR in real time. They labeled the cells as soon as the AR started but they showed different kinetic properties. SBTI-FITC filled the acrosome in 1,5 minutes and then the marker was released. On the contrary PSA-FITC was not liberated from the sperm. Our results indicate that acrosomal exocytosis can be monitored with high temporal and spatial resolution by confocal microscopy.