scholarly journals A cAMP Regulated K+-Selective Channel from the Sea Urchin Sperm Plasma Membrane

1996 ◽  
Vol 174 (2) ◽  
pp. 271-280 ◽  
Author(s):  
Pedro Labarca ◽  
Celia Santi ◽  
Otilia Zapata ◽  
Ezequiel Morales ◽  
Carmen Beltrán ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Sperm Plasma Membrane ◽  
Selective Channel ◽  
Sea Urchin Sperm

Anion channels in the sea urchin sperm plasma membrane

1993 ◽  
Vol 36 (2) ◽  
pp. 174-182 ◽  
Author(s):  
Ezequiel Morales ◽  
Lucia De La Torre ◽  
Gary W. Moy ◽  
Victor D. Vacquier ◽  
Alberto Darszon
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Anion Channels ◽  
Sperm Plasma Membrane ◽  
Sea Urchin Sperm

scholarly journals Ca2+ channels from the sea urchin sperm plasma membrane.

1990 ◽  
Vol 95 (2) ◽  
pp. 273-296 ◽  
Author(s):  
A Liévano ◽  
E C Vega-SaenzdeMiera ◽  
A Darszon
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Acrosome Reaction ◽  
Main Channel ◽  
Open Probability ◽  
Boltzmann Function ◽  
Sperm Plasma Membrane ◽  
Egg Jelly ◽  
Sea Urchin Sperm ◽  
Ca2 Channels

Ca2+ influx across the sea urchin sperm plasma membrane is a necessary step during the egg jelly-induced acrosome reaction. There is pharmacological evidence for the involvement of Ca2+ channels in this influx, but their presence has not been directly demonstrated because of the small size of this cell. Sea urchin sperm Ca2+ channels are being studied by fusing isolated plasma membranes into planar lipid bilayers. With this strategy, a Ca2+ channel has been detected with the following characteristics: (a) the channel exhibits a high mainstate conductance (gamma MS) of 172 pS in 50 mM CaCl2 solutions with voltage-dependent decaying to smaller conductance states at negative Em; (b) the channel is blocked by millimolar concentrations of Cd2+, Co2+, and La3+, which also inhibit the egg jelly-induced acrosome reaction; (c) the gamma MS conductance sequence for the tested divalent cations is the following: Ba2+ greater than Sr2+ greater than Ca2+; and (d) the channel discriminates poorly for divalent over monovalent cations (PCa/PNa = 5.9). The sperm Ca2+ channel gamma MS rectifies in symmetrical 10 mM CaCl2, having a maximal slope conductance value of 94 pS at +100 mV applied to the cis side of the bilayer. Under these conditions, a different single-channel activity of lesser conductance became apparent above the gamma MS current at positive membrane potentials. Also in 10 mM Ca2+ solutions, Mg2+ permeates through the main channel when added to the cis side with a PCa/PMg = 2.9, while it blocks when added to the trans side. In 50 mM Ca2+ solutions, the gamma MS open probability has values of 1.0 at voltages more positive than -40 mV and decreases at more negatives potentials, following a Boltzmann function with an E0.5 = -72 mV and an apparent gating charge value of 3.9. These results describe a novel Ca2(+)-selective channel, and suggest that the main channel works as a single multipore assembly.

scholarly journals Ligands and receptors mediating signal transduction in sea urchin spermatozoa

Reproduction ◽  
2004 ◽  
Vol 127 (2) ◽  
pp. 141-149 ◽  
Author(s):  
Anna T Neill ◽  
Victor D Vacquier
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Signaling Pathways ◽  
Sea Urchin ◽  
Acrosome Reaction ◽  
Sea Urchins ◽  
Model System ◽  
Surrounding Seawater ◽  
Sea Urchin Sperm

Sea urchins have long been a model system for the study of fertilization. Much has been learned about how sea urchin sperm locate and fertilize the egg. Sperm and eggs are spawned simultaneously into the surrounding seawater. Sperm signaling pathways lead to downstream events that ensure fertilization. Upon spawning, sperm must acquire motility and then they must swim towards or respond to the egg in some way. Finally, they must undergo a terminal exocytotic event known as the acrosome reaction that allows the sperm to bind to the vitelline layer of the egg and then to fuse with the egg plasma membrane. Motility is stimulated by exposure to seawater, while later events are orchestrated by factors from the egg. The sperm signaling pathways are exquisitely tuned to bring the sperm to the egg, bind, and fuse the two cells as quickly as possible.

Ionic Channels in Sea Urchin Sperm Physiology

Physiology ◽  
1988 ◽  
Vol 3 (5) ◽  
pp. 181-185
Author(s):  
A Darszon ◽  
A Guerrero ◽  
A Lievano ◽  
M Gonzalez-Martinez ◽  
E Morales
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Acrosome Reaction ◽  
Ionic Channels ◽  
Good Evidence ◽  
Ionic Fluxes ◽  
Sea Urchin Sperm

In sea urchin sperm, ionic fluxes modulate the activation of respiration and motility and the acrosome reaction, a prerequisite for egg fertilization. Ionic channels are present in the plasma membrane of these cells, and there is good evidence indicating that they are deeply involved in these processes.

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