Sperm activation in species with external fertilisation

Zygote ◽  
1994 ◽  
Vol 2 (4) ◽  
pp. 359-361 ◽  
Author(s):  
Elisabetta Tosit
Keyword(s):  
Sea Urchin ◽  
Acrosome Reaction ◽  
Quiescent State ◽  
Sperm Activation ◽  
Excitable Cell

The spermatoozoon is an excitable cell that responds to specific effectors by rapidly changing its behaviour. In species with external fertilisation, spermatozoa are stored in a quiescent state in the testis, but within seconds after spawning, dilution into water triggers several activation events such as increases in motility and respiration. In some species, these are followed by the acrosome reaction, an exocytotic process that allows the spermatozoon to penetrate the egg investments and activate the egg (Dale, 1983). The majority of information on sperm activation has come from the sea urchin; secondarily teleosts and starfish have proved to be useful models.

Mechanism of human sperm activation by extracellular ATP

1996 ◽  
Vol 270 (6) ◽  
pp. C1709-C1714 ◽  
Author(s):  
C. Foresta ◽  
M. Rossato ◽  
P. Chiozzi ◽  
F. Di Virgilio
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Human Sperm ◽  
Extracellular Atp ◽  
Effective Concentration ◽  
Na Channel ◽  
Monovalent Cations ◽  
Sperm Activation ◽  
Gated Channel ◽  
Sperm Plasma Membrane

We have identified the mechanism whereby extracellular ATP (ATPe) triggers the acrosome reaction in human spermatozoa. This nucleotide opens a ligand-gated ion channel expressed on the sperm plasma membrane. ATPe threshold and 50% effective concentration calculated on the total added ATPe are 0.1 and 2 mM, respectively, corresponding to a free ATP concentration (ATP4-) of 3 and 200 microM, respectively. The ATPe-gated channel is selective for monovalent cations (Na+, choline, and methylglucamine), whereas on the contrary, permeability to Ca2+ is negligible. Isosmolar replacement of extracellular Na+ with sucrose fully blocked ATPe-dependent sperm activation, thus suggesting a mandatory role for Na+ influx. These results show that human sperm express an ATPe-gated Na+ channel that might have an important role in sperm activation before egg fertilization.

scholarly journals The Calcium-mobilizing Messenger Nicotinic Acid Adenine Dinucleotide Phosphate Participates in Sperm Activation by Mediating the Acrosome Reaction

2010 ◽  
Vol 285 (24) ◽  
pp. 18262-18269 ◽  
Author(s):  
Sridhar R. Vasudevan ◽  
Alexander M. Lewis ◽  
Jennifer W. Chan ◽  
Claire L. Machin ◽  
Debroshi Sinha ◽  
...  
Keyword(s):  
Nicotinic Acid ◽  
Acrosome Reaction ◽  
Sperm Activation

Ion channel activity of membrane vesicles released from sea urchin sperm during the acrosome reaction

2004 ◽  
Vol 321 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Joseph R. Schulz ◽  
Jose L. De La Vega-Beltrán ◽  
Carmen Beltrán ◽  
Victor D. Vacquier ◽  
Alberto Darszon
Keyword(s):  
Ion Channel ◽  
Sea Urchin ◽  
Acrosome Reaction ◽  
Membrane Vesicles ◽  
Channel Activity ◽  
Sea Urchin Sperm

Species-specificity of the acrosome reaction in starfish

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S62-S62 ◽  
Author(s):  
Midori Matsumoto ◽  
Masako Ikeda ◽  
Motonori Hoshi
Keyword(s):  
Acrosome Reaction ◽  
Molecular Size ◽  
Type Structure ◽  
Follicle Cells ◽  
Cdna Clones ◽  
Steroid Saponin ◽  
Sperm Activation ◽  
Amino Terminal ◽  
High Calcium ◽  
Species Specific

Animal eggs are generally encased in extracellular investments. These structures are not simply a protective barrier against infectious microbes, parasites and various small predators: in starfish, three components of the egg jelly, the outermost egg investment, are responsible for triggering the acrosome reaction. These components are a highly sulphated glycoprotein of an extremely large molecular size named acrosome reaction-inducing substance (ARIS), a steroid saponin named Co-ARIS, and asteroidal sperm-activating peptides (asterosaps) (Matsui et al., 1986a, b; Nishigaki et al., 1996). ARIS can induce the acrosome reaction in homologous spermatozoa with asterosaps or Co-ARIS in normal seawater. Specificity at the genus or order level was found for sperm activation by asterosaps, whereas the acrosome reaction by jelly components was species-specific. The main sugar saccharide chain of ARIS, composed of the pentasaccharide repeating units [Xyl-Gal-Fuc(SO3−)-Fuc(3−)-Fuc-], has been observed to induce the acrosome reaction in starfish sperm at high calcium concentrations (Koyota et al., 1997). Recently, we cloned cDNAs encoding asterosaps and elucidated their nucleotide sequences (Matsumoto et al., 1999). The mRNA encoding asterosaps was transcribed only in the oocytes but not in the follicle cells, and the length was 3.7 kb. The cDNA clones contained multiple isoforms of asterosaps. We assume that asterosap cursors are large prepolypeptide chains with an unusual ‘rosary-type’ structure composed of 10 successive similar stretches of 51–55 residues. Each stretch ends with a ‘spacer’ of 17–21 residues immediately followed by the sequence of one asterosap isoform. The amino terminal of this precursor has 19–21 successive glutamine-rich repeating units.

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