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.

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.

Crosstalk between protein kinases A and C regulates sea urchin sperm motility

Zygote ◽  
2021 ◽  
pp. 1-12
Author(s):  
Arlet Loza-Huerta ◽  
Hiram Pacheco-Castillo ◽  
Alberto Darszon ◽  
Carmen Beltrán
Keyword(s):  
Protein Kinase ◽  
Sperm Motility ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Dependent Protein Kinase ◽  
Kinase C ◽  
Competitive Inhibitors ◽  
Motility Regulation ◽  
Dependent Protein ◽  
Sea Urchin Sperm

Summary Fertilization, a crucial event for species preservation, in sea urchins, as in many other organisms, requires sperm motility regulation. In Strongylocentrotus purpuratus sea urchins, speract, a sperm chemoattractant component released to seawater from the outer egg layer, attracts sperm after binding to its receptor in the sperm flagellum. Previous experiments performed in demembranated sperm indicated that motility regulation in these cells involved protein phosphorylation mainly due to the cAMP-dependent protein kinase (PKA). However, little information is known about the involvement of protein kinase C (PKC) in this process. In this work, using intact S. purpuratus sea urchin sperm, we show that: (i) the levels of both phosphorylated PKA (PKA substrates) and PKC (PKC substrates) substrates change between immotile, motile and speract-stimulated sperm, and (ii) the non-competitive PKA (H89) and PKC (chelerythrine) inhibitors diminish the circular velocity of sperm and alter the phosphorylation levels of PKA substrates and PKC substrates, while the competitive inhibitors Rp-cAMP and bisindolylmaleimide (BIM) do not. Altogether, our results show that both PKA and PKC participate in sperm motility regulation through a crosstalk in the signalling pathway. These results contribute to a better understanding of the mechanisms that govern motility in sea urchin sperm.

The Centriole-Centrosome Complex is Affected by Microgravity During Cell Division and in Cilia of Sea Urchin Embryos: Results from Space Flight Experiments

1998 ◽  
Vol 4 (S2) ◽  
pp. 1132-1133
Author(s):  
Heide Schatten ◽  
Amitabha Chakrabarti ◽  
Meghan Taylor ◽  
Michael Crosser ◽  
Kirk Mitchell
Keyword(s):  
Cell Division ◽  
Sea Urchin ◽  
Space Flight ◽  
Space Shuttle ◽  
Sea Urchins ◽  
Culture Conditions ◽  
Model System ◽  
Research Facility ◽  
Cilia Formation ◽  
Pluteus Stage

Sea urchins have been used for over a century as a remarkable animal model system in which to study cell, molecular, and developmental biology. The studies presented here have used sea urchin eggs and embryos for pioneering experiments to explore the effects of microgravity on the cytoskeleton during a space flight on the space shuttle Endeavor. The culture conditions followed those described previously utilizing the Aquatic Research Facility (ARF) to fertilize and culture eggs and embryos up to the pluteus stage under controlled temperature (12°C) and fixation conditions. To achieve a final fixation with 0.5% glutaraldehyde and 4μM taxol, concentrated fixation fluid was injected at preselected time points to preserve microtubules, centrioles, centrosomes, microfilaments, mitochondria, and cell membranes.The analysis of the results revealed that the centriole-centrosome complex during cell division and cilia formation showed alterations in samples that had been exposed to microgravity while control cells cultured in a centrifuge at lg in space and those cultured on ground appeared normal.

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
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