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Speract induces calcium oscillations in the sperm tail.

Wood CD, Darszon A, Whitaker M - J. Cell Biol. (2003)

Bottom Line: These data point to a model in which a messenger generated periodically in the tail diffuses to the head.Sperm are highly polarized cells.Our results indicate that a clear understanding of the link between [Ca2+]i and sperm motility will only be gained by analysis of [Ca2+]i signals at the level of the single sperm.

View Article: PubMed Central - PubMed

Affiliation: School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, NE2 4HH, UK.

ABSTRACT
Sea urchin sperm motility is modulated by sperm-activating peptides. One such peptide, speract, induces changes in intracellular free calcium concentration ([Ca2+]i). High resolution imaging of single sperm reveals that speract-induced changes in [Ca2+]i have a complex spatiotemporal structure. [Ca2+]i increases arise in the tail as periodic oscillations; [Ca2+]i increases in the sperm head lag those in the tail and appear to result from the summation of the tail signal transduction events. The period depends on speract concentration. Infrequent spontaneous [Ca2+]i transients were also seen in the tail of unstimulated sperm, again with the head lagging the tail. Speract-induced fluctuations were sensitive to membrane potential and calcium channel blockers, and were potentiated by niflumic acid, an anion channel blocker. 3-isobutyl-1-methylxanthine, which potentiates the cGMP/cAMP-signaling pathways, abolished the [Ca2+]i fluctuations in the tail, leading to a very delayed and sustained [Ca2+]i increase in the head. These data point to a model in which a messenger generated periodically in the tail diffuses to the head. Sperm are highly polarized cells. Our results indicate that a clear understanding of the link between [Ca2+]i and sperm motility will only be gained by analysis of [Ca2+]i signals at the level of the single sperm.

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Representative example of the effect of niflumic acid treatment on speract-induced [Ca2+]i increases in individual sperm. Sperm treated with 100 μM niflumic acid before addition of 1 nM speract (indicated by arrow). Changes in [Ca2+]i were determined for heads and flagella by ratioing their fluorescence (F) against their initial fluorescence (F0).
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fig8: Representative example of the effect of niflumic acid treatment on speract-induced [Ca2+]i increases in individual sperm. Sperm treated with 100 μM niflumic acid before addition of 1 nM speract (indicated by arrow). Changes in [Ca2+]i were determined for heads and flagella by ratioing their fluorescence (F) against their initial fluorescence (F0).

Mentions: It has been reported that sperm possess anion channels and that they may contribute to the resting Em and influence the AR (Morales et al., 1993). Fig. 8 shows that niflumic acid (NA), an antagonist of anion and nonselective cation channels profoundly affects the speract-induced [Ca2+]i fluctuations. At a concentration of 100 μM, it significantly increases the magnitude of [Ca2+]i fluctuations (6.2 ± 0.3-fold increase in flagella [Ca2+]i; n = 5, P < 0.001; unpaired two-tailed t test, in comparison with Table II) and reduces their frequency (2.4 ± 0.3 fluctuations per 10-s post-1 nM speract addition; n = 5, P < 0.001; unpaired two-tailed t test, in comparison with Fig. 4 B). These results suggest that anion channel(s) are important elements of a pacemaker-type mechanism that may underlie the speract-induced fluctuations.


Speract induces calcium oscillations in the sperm tail.

Wood CD, Darszon A, Whitaker M - J. Cell Biol. (2003)

Representative example of the effect of niflumic acid treatment on speract-induced [Ca2+]i increases in individual sperm. Sperm treated with 100 μM niflumic acid before addition of 1 nM speract (indicated by arrow). Changes in [Ca2+]i were determined for heads and flagella by ratioing their fluorescence (F) against their initial fluorescence (F0).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172867&req=5

fig8: Representative example of the effect of niflumic acid treatment on speract-induced [Ca2+]i increases in individual sperm. Sperm treated with 100 μM niflumic acid before addition of 1 nM speract (indicated by arrow). Changes in [Ca2+]i were determined for heads and flagella by ratioing their fluorescence (F) against their initial fluorescence (F0).
Mentions: It has been reported that sperm possess anion channels and that they may contribute to the resting Em and influence the AR (Morales et al., 1993). Fig. 8 shows that niflumic acid (NA), an antagonist of anion and nonselective cation channels profoundly affects the speract-induced [Ca2+]i fluctuations. At a concentration of 100 μM, it significantly increases the magnitude of [Ca2+]i fluctuations (6.2 ± 0.3-fold increase in flagella [Ca2+]i; n = 5, P < 0.001; unpaired two-tailed t test, in comparison with Table II) and reduces their frequency (2.4 ± 0.3 fluctuations per 10-s post-1 nM speract addition; n = 5, P < 0.001; unpaired two-tailed t test, in comparison with Fig. 4 B). These results suggest that anion channel(s) are important elements of a pacemaker-type mechanism that may underlie the speract-induced fluctuations.

Bottom Line: These data point to a model in which a messenger generated periodically in the tail diffuses to the head.Sperm are highly polarized cells.Our results indicate that a clear understanding of the link between [Ca2+]i and sperm motility will only be gained by analysis of [Ca2+]i signals at the level of the single sperm.

View Article: PubMed Central - PubMed

Affiliation: School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, NE2 4HH, UK.

ABSTRACT
Sea urchin sperm motility is modulated by sperm-activating peptides. One such peptide, speract, induces changes in intracellular free calcium concentration ([Ca2+]i). High resolution imaging of single sperm reveals that speract-induced changes in [Ca2+]i have a complex spatiotemporal structure. [Ca2+]i increases arise in the tail as periodic oscillations; [Ca2+]i increases in the sperm head lag those in the tail and appear to result from the summation of the tail signal transduction events. The period depends on speract concentration. Infrequent spontaneous [Ca2+]i transients were also seen in the tail of unstimulated sperm, again with the head lagging the tail. Speract-induced fluctuations were sensitive to membrane potential and calcium channel blockers, and were potentiated by niflumic acid, an anion channel blocker. 3-isobutyl-1-methylxanthine, which potentiates the cGMP/cAMP-signaling pathways, abolished the [Ca2+]i fluctuations in the tail, leading to a very delayed and sustained [Ca2+]i increase in the head. These data point to a model in which a messenger generated periodically in the tail diffuses to the head. Sperm are highly polarized cells. Our results indicate that a clear understanding of the link between [Ca2+]i and sperm motility will only be gained by analysis of [Ca2+]i signals at the level of the single sperm.

Show MeSH
Related in: MedlinePlus