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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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Subregional analysis of [Ca2+]i increases in individual sperm. (A) After addition of 100 nM speract, the time taken for the initial calcium increase to reach half height (relative to the first point of increase in the flagellum) was recorded for subregions of the sperm head and flagellum (B); n = 5, error bars indicate ± SEM. One-tailed t test (comparison to flagellum). ***, P < 0.001; **, P < 0.01; ns, P > 0.05.
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fig3: Subregional analysis of [Ca2+]i increases in individual sperm. (A) After addition of 100 nM speract, the time taken for the initial calcium increase to reach half height (relative to the first point of increase in the flagellum) was recorded for subregions of the sperm head and flagellum (B); n = 5, error bars indicate ± SEM. One-tailed t test (comparison to flagellum). ***, P < 0.001; **, P < 0.01; ns, P > 0.05.

Mentions: Fig. 3 illustrates how the speract-induced [Ca2+]i elevation appears to initiate in the flagella and spread from there to the head. The t1/2 of the initial [Ca2+]i elevation increases progressively with distance from the flagella (Fig. 3 A), and there is an ∼1-s interval between the attainment of peak [Ca2+]i in the flagellum and the tip of the head (Fig. 3 B; n = 5). Subsequent fluctuations show similar kinetic characteristics, as do spontaneous calcium fluctuations (unpublished data). These findings, together with those in Fig. 2, suggest that the [Ca2+]i increase in the head results from the summation of [Ca2+]i and/or cyclic nucleotide changes that occur in the flagella.


Speract induces calcium oscillations in the sperm tail.

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

Subregional analysis of [Ca2+]i increases in individual sperm. (A) After addition of 100 nM speract, the time taken for the initial calcium increase to reach half height (relative to the first point of increase in the flagellum) was recorded for subregions of the sperm head and flagellum (B); n = 5, error bars indicate ± SEM. One-tailed t test (comparison to flagellum). ***, P < 0.001; **, P < 0.01; ns, P > 0.05.
© Copyright Policy
Related In: Results  -  Collection

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

fig3: Subregional analysis of [Ca2+]i increases in individual sperm. (A) After addition of 100 nM speract, the time taken for the initial calcium increase to reach half height (relative to the first point of increase in the flagellum) was recorded for subregions of the sperm head and flagellum (B); n = 5, error bars indicate ± SEM. One-tailed t test (comparison to flagellum). ***, P < 0.001; **, P < 0.01; ns, P > 0.05.
Mentions: Fig. 3 illustrates how the speract-induced [Ca2+]i elevation appears to initiate in the flagella and spread from there to the head. The t1/2 of the initial [Ca2+]i elevation increases progressively with distance from the flagella (Fig. 3 A), and there is an ∼1-s interval between the attainment of peak [Ca2+]i in the flagellum and the tip of the head (Fig. 3 B; n = 5). Subsequent fluctuations show similar kinetic characteristics, as do spontaneous calcium fluctuations (unpublished data). These findings, together with those in Fig. 2, suggest that the [Ca2+]i increase in the head results from the summation of [Ca2+]i and/or cyclic nucleotide changes that occur in the flagella.

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