INIBIBB   05455
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BAHIA BLANCA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Lipid changes in rat spermatozoa during Isolation and functional activation in vitro
Autor/es:
ORESTI, G.M.; PEÑALVA, D.A.; LUQUEZ, J.M.; ANTOLLINI, S.S.; AVELDAÑO, M.I.
Lugar:
MENDOZA
Reunión:
Congreso; XLVIII Reunión Nacional de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2012
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)
Resumen:
Hydrolysis of glycerophospholipids (GPL) and
sphingomyelin (SM) are calcium-dependent reactions that are significantly stimulated
in rat epididymal spermatozoa during incubations leading to capacitation (Cap)
and particularly after acrosomal reaction (AR). In comparison with gametes
whose contact during isolation with tissue divalent cations was avoided (C1),
or kept to a minimum (C2), those used as controls in these incubations (C3) already
had their glycerophospholipids (GPL) and sphingomyelin (SM) partially
hydrolyzed. Using C1 as controls, the C3 gametes had less GPL per cell and more
free fatty acids. The latter were released with cholesterol from cells to media
during albumindependent capacitation. Significant decreases in membrane GPL occurred
gradually in the order C1 > C2 > C3 > Cap > AR. Diminution in the
major choline GPL specifically targeted phosphatidylcholine in the presence of
a virtually unchanged amount of plasmenylcholine, the acrosome-reacted cells
thus becoming relatively rich in plasmalogens. The uniqueSMwith very long chain
PUFAlocated on sperm heads was intact in C1 cells and maximally hydrolyzed into
ceramides after completion of AR. Using fluorescent probes, liposomes prepared
from the 5 conditions showed that C1 gametes had the minimun degree of order of
the lipid bilayer, this increasing significantly as Cap and AR proceeded.