Membrane domains in guinea pig sperm and their role in the membrane fusion events of the acrosome reaction

1988 ◽  
Vol 220 (3) ◽  
pp. 267-280 ◽  
Author(s):  
Sean P. Flaherty ◽  
Gary E. Olson
Keyword(s):  
Guinea Pig ◽  
Membrane Fusion ◽  
Acrosome Reaction ◽  
Membrane Domains

scholarly journals Sodium requirement for capacitation and membrane fusion during the guinea-pig sperm acrosome reaction

Reproduction ◽  
1984 ◽  
Vol 70 (1) ◽  
pp. 83-94 ◽  
Author(s):  
R. V. Hyne ◽  
R. E. Higginson ◽  
D. Kohlman ◽  
A. Lopata
Keyword(s):  
Guinea Pig ◽  
Membrane Fusion ◽  
Acrosome Reaction ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

scholarly journals The effect of permeant and impermeant osmoticants on exocytosis in guinea pig sperm

1991 ◽  
Vol 100 (4) ◽  
pp. 761-769
Author(s):  
D.P. Green
Keyword(s):  
Electron Microscopy ◽  
Guinea Pig ◽  
Membrane Fusion ◽  
Acrosome Reaction ◽  
Ammonium Acetate ◽  
Ammonium Acetate Solution ◽  
Acetate Solution ◽  
Normal Medium ◽  
Acrosomal Membrane ◽  
External Calcium

Guinea pig sperm were suspended in calcium-containing medium supplemented with various concentrations of the tetrasaccharide, stachyose. At concentrations up to and including 0.6 M, stachyose was without effect on the A23187-induced acrosome reaction. At 1.0 M stachyose, greater than 97% of sperm retained their acrosome after exposure to A23187, as judged by light microscopy. Electron microscopy demonstrated, however, that exocytotic membrane fusion had occurred, although with substantial retention of the acrosomal matrix. Sperm incubated in 1.0 M stachyose solutions also underwent exocytotic membrane fusion in the absence of A23187 and external calcium. Sperm suspended in 0.175 M ammonium chloride solution progressively lost motility over 30 min, but without acrosomal swelling. By contrast, sperm in 0.19 M ammonium acetate underwent substantial swelling of the acrosome within 2–5 min. 70–80% of these sperm were able to exclude the vital dye propidium iodide with their acrosomes swollen. These sperm underwent acrosomal shrinkage if resuspended in normal medium within 5–10 min, and the majority (60–70%) recovered some motility. These sperm could undergo an A23187-induced acrosome reaction. Electron microscopy indicated that swelling in ammonium acetate solution solubilizes much of the acrosomal matrix and causes internal fusion between adjacent regions of the outer acrosomal membrane. There was no exocytotic membrane fusion in ammonium acetate solution, however. The evidence suggests that there is no stachyose osmolality for guinea pig sperm which will suppress the membrane fusion associated with exocytosis, and that sufficiently high osmolalities cause exocytotic membrane fusion in the absence of calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Proteases are not involved in the membrane fusion events of the lysolecithin-mediated guinea pig sperm acrosome reaction

1993 ◽  
Vol 104 (1) ◽  
pp. 163-172
Author(s):  
S.P. Flaherty ◽  
N.J. Swann
Keyword(s):  
Guinea Pig ◽  
Membrane Fusion ◽  
Protease Inhibitors ◽  
Acrosome Reaction ◽  
Structural Pattern ◽  
Wide Range ◽  
Bean Trypsin Inhibitor ◽  
Specific Protease ◽  
Sperm Acrosome Reaction ◽  
Sperm Acrosome

The guinea pig sperm acrosome reaction is characterized by a complex temporal and structural pattern of membrane fusions. In this study, we have used specific protease inhibitors to determine if proteases regulate this pattern of membrane fusions during the lysolecithin-mediated guinea pig sperm acrosome reaction. Inhibitors were chosen so as to cover a wide range of different types of proteases, and all were used at the highest concentration that did not adversely affect sperm motility. Of the eight inhibitors tested, leupeptin, soya bean trypsin inhibitor (SBTI), p-aminobenzamidine (pAB) and nitrophenyl p'-guanidino benzoate (NPGB) inhibited completion of the acrosome reaction, while diethylenetriaminepentaacetic acid (DTPA), phosphoramidon, bestatin and pepstatin had no effect. Sperm that had been acrosome-reacted in the presence of each inhibitor were examined by transmission electron microscopy to assess whether the inhibitors altered the pattern of membrane fusions during the acrosome reaction. DTPA, phosphoramidon, bestatin and pepstatin had no effect on membrane fusion or matrix dispersal. Serine protease inhibitors such as leupeptin, SBTI, pAB and NPGB prevented complete dispersal of the acrosomal matrix and completion of the acrosome reaction, but did not alter the temporal sequence or structural pattern of membrane fusions. The undispersed matrix was present along the dorsal and ventral aspects of the apical segment and throughout the principal segment. We conclude that proteases are not involved in regulating the temporal and structural pattern of membrane fusions which occurs during the lysolecithin-mediated acrosome reaction of guinea pig sperm.

scholarly journals The course of the acrosome reaction in guinea-pig sperm

1982 ◽  
Vol 54 (1) ◽  
pp. 161-171
Author(s):  
D.P. Green
Keyword(s):  
Guinea Pig ◽  
Membrane Fusion ◽  
Osmotic Pressure ◽  
Acrosome Reaction ◽  
Plasma Membranes ◽  
Calcium Ionophore ◽  
Colloid Osmotic Pressure ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Sequence Of Events

The acrosome reaction in guinea-pig sperm is accompanied by a marked cavitation of the acrosomal contents. Two divergent views are held as to whether this cavitation precedes or follows the membrane fusion that occurs in the reaction. To distinguish between these 2 views cavitation was induced in media containing a colloid, either Ficoll 70 or inulin, either by inducing a normal acrosome reaction using the calcium ionophore A23187 or by using the detergent Triton X100. Both Ficoll 70 and inulin, when incorporated into media of normal osmolality, were able to suppress various features of the cavitation. Complete retention of acrosomal shape was achieved in sperm treated with detergent in 30% (W/V) Ficoll 70 solution despite the absence of the limiting acrosomal and plasma membranes. This evidence supports the suggestion that the cause of the cavitation is a colloid osmotic pressure within the acrosomal matrix. This in turn supports one of the 2 proposed mechanisms for the temporal sequence of events occurring in the acrosome reaction.

scholarly journals Modifications of anionic-lipid domains preceding membrane fusion in guinea pig sperm.

1982 ◽  
Vol 92 (3) ◽  
pp. 604-615 ◽  
Author(s):  
E L Bearer ◽  
D S Friend
Keyword(s):  
Plasma Membrane ◽  
Guinea Pig ◽  
Membrane Fusion ◽  
Acrosome Reaction ◽  
Lipid Extraction ◽  
Surface Coat ◽  
Lipid Domains ◽  
Membrane Function ◽  
Anionic Lipid ◽  
Sperm Membrane

The relationship between anionic-lipid concentration and the functional properties of plasma-membrane domains was explored using the guinea-pig sperm membrane as a model, with polymyxin B (PXB) as a probe. Areas of plasmalemma specialized for fusion during the acrosome reaction had a higher affinity for the probe than adjacent nonfusigenic regions. In addition, capacitation--a process preceding acrosome:plasma-membrane fusion--markedly enlarged the area susceptible to PXB binding over the acrosomal cap. Protease treatment mimicked capacitation by increasing the acrosome-reaction incidence as well as PXB binding, at enzyme concentrations not affecting the surface coat nor altering filipin/sterol localization. Both proteolytic digestion and capacitation failed to augment PXB- or filipin-affinity in nonfusigenic zones, such as the post-acrosomal segment, including its particle-free maculae. Incubation of sperm in capacitating medium supplemented with 32P-labeled phosphate, followed by lipid extraction, thin-layer chromatography, and autoradiography, revealed a radioactive band comigrating with cardiolipin and phosphatidic acid. Vermiform protrusions elicited by PXB in the outer lamellae of cardiolipin-phosphatidylcholine liposomes resembled those seen in fusional regions of sperm membrane. We conclude that (a) differing concentrations of anionic lipids are found in adjacent domains of the sperm plasma membrane; (b) these domains mirror the functional regions of the membrane, with higher anionic-lipid concentrations localized over fusional zones; (c) the surface coat does not participate in the maintenance of such domains; (d) anionic-lipid synthesis may contribute to their formation; and (e) anionic-lipid concentrations increase as the membrane becomes fusionally competent, indicating that cellular modulation of lipid domains accompanies regulation of membrane function.

In guinea pig spermatozoa, the procaine-promoted synchronous acrosome reaction results in highly fertile cells exhibiting normal F-actin distribution

2006 ◽  
Vol 21 (2) ◽  
pp. 208-215 ◽  
Author(s):  
Manuel Sánchez-Gutiérrez ◽  
Norma Laura Delgado-Buenrostro ◽  
Margarita Zárate-Grande ◽  
Salvador Uribe ◽  
Adela Mújica
Keyword(s):  
Guinea Pig ◽  
Acrosome Reaction

The induction of the acrosome reaction in guinea-pig sperm by the divalent metal cation ionophore A23187

1978 ◽  
Vol 32 (1) ◽  
pp. 137-151
Author(s):  
D.P. Green
Keyword(s):  
Guinea Pig ◽  
Metal Cation ◽  
Acrosome Reaction ◽  
Divalent Metal ◽  
Secretory Cells ◽  
Free Calcium ◽  
Ionophore A23187 ◽  
Divalent Metal Cation ◽  
Free Calcium Concentration ◽  
External Calcium

The divalent metal cation ionophore A23187 induces an acrosome reaction in guinea-pig sperm which is dependent on external calcium. Examination of this acrosome reaction by electron microscopy shows that it is morphologically normal. The known properties of A23187 and the morphological similarity between the acrosome reaction and the secretory discharges of other secretory cells suggests that the immediate cause of the acrosome reaction is an increase in the cytoplasmic free calcium concentration.

The activation of proteolysis in the acrosome reaction of guinea-pig sperm

1978 ◽  
Vol 32 (1) ◽  
pp. 153-164
Author(s):  
D.P. Green
Keyword(s):  
Guinea Pig ◽  
Acrosome Reaction ◽  
Morphological Changes ◽  
Divalent Metal ◽  
Free Calcium ◽  
Ionophore A23187 ◽  
Reaction Proceeds ◽  
Insoluble Form ◽  
Acrosin Activity ◽  
Sperm Population

The divalent metal cation ionophore A23187 rapidly induces a normal acrosome reaction in a population of guinea-pig sperm suspended in calcium medium. In the course of the acrosome reaction, proacrosin, the zymogen precursor of the protease acrosin, is activated. Although the acrosome reaction causes exocytosis of the acrosomal contents, ‘soluble’ acrosin is not released in significant amounts until well after the sperm population as a whole has undergone an acrosome reaction. This suggests that proacrosin is stored within the acrosome in an insoluble form and that exocytosis of the acrosomal contents in the acrosome reaction is insufficient, by itself, to cause its immediate dissolution. Electron micrographs of sperm undergoing an A23187-induced acrosome reaction in the presence of the acrosin inhibitors benzamidine, p-amino-benzamidine and phenylmethylsulphonyl fluoride show that the acrosome reaction proceeds normally but that dispersal of the acrosomal contents is inhibited. These morphological changes are, for the most part, below the limit of resolution of the light microscope and using light microscopy to assess whether an acrosome reaction has taken place, it can be mistakenly inferred that the reaction itself is inhibited by the acrosin inhibitors. The inhibition of the dispersal of the acrosomal contents by acrosin inhibitors suggests that acrosin activity is important in solubilizing acrosin. These experimental observations, taken with the evidence that the acrosome reaction is a response to an increase in intracellular free calcium, have been taken as the basis of a proposal for the mechanism of proacrosin activation in the acrosome reaction.

scholarly journals Induction of Accelerated Acrosome Reaction in Guinea Pig Sperm1

1980 ◽  
Vol 22 (3) ◽  
pp. 566-570 ◽  
Author(s):  
Jai Pal Singh ◽  
Donner F. Babcock ◽  
Henry A. Lardy
Keyword(s):  
Guinea Pig ◽  
Acrosome Reaction
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