INVESTIGADORES
DE BLAS Gerardo Andres
congresos y reuniones científicas
Título:
KINETICS OF THE ACROSOMAL EXOCYTOSIS IN HUMAN SPERM
Autor/es:
SOSA C; ZANETTI N; ZOPPINO M; DE BLAS GA; MAYORGA LS
Lugar:
Buenos Aires
Reunión:
Congreso; Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2013
Resumen:
Our laboratory has shown that sperm and neuroendocrinal cells use
similar molecular mechanism for secretion. However, we report
here that the process is orders of magnitude slower. For these
experiments, capacitated human sperm were stimulated with
progesterone or with the calcium ionophore A23187 in the presence
of a fluorescent lectin. The incorporation of the lectin into the
acrosome -indicating fusion pore opening- was assessed in fixed or
live cells by fluorescence microscopy or flow cytometry. Despite
the slow kinetics of the exocytosis, the cytosolic calcium increased
triggered by the stimuli occurred in seconds. To assess if acrosomal
swelling, a process required for exocytosis, was responsible for the
delay, we measured the kinetics of this process and observed that it
required several minutes to be completed. We then tested the kinetics
of fusion pore opening in sperm that had completed the swelling.
For these experiments intraacrosomal calcium was depleted using
the photosensitive calcium chelator NP-EGTA and sperm were
stimulated with A23187. Exocytosis was completed when the
chelator was photo-inactivated. Under these conditions the pores
opened in seconds. These observations indicate that the acrosome
reaction requires a preparation time, probably related to acrosomal
swelling, whereas the fusion pore opening occurs with a fast kinetics