Fig 1.
Effect of salinity on sperm motility (%, A) in Eastern oyster, Crassostrea virginica. Sperm motility was activated in high salinity seawater diluted to salinities of 4 to 32 PSU. Average motility at each salinity (B) and time post-activation (C) is displayed. D shows a second-order polynomial regression for the effects of salinity on sperm motility at 15 min post-activation. Sperm head trajectories at each salinity are shown (E). Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 5). Treatments with different superscripts significantly differ (p < 0.05). A motility of 0% was indicated by asterisk.
Fig 2.
Effect of salinity on sperm velocity (μm/s, A) in Eastern oyster, Crassostrea virginica. Sperm motility was activated in high salinity seawater diluted to salinities of 4 to 32 PSU. Average velocity at each salinity (B) and time post-activation (C) is displayed. D shows a second-order polynomial regression for the effects of salinity on sperm velocity at 15 min post-activation. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 5). Treatments with different superscripts significantly differ (p < 0.05). A velocity of 0 μm/s was indicated by asterisk.
Fig 3.
Effect of pH on sperm motility (%, A) in Eastern oyster, Crassostrea virginica. Sperm motility was activated in artificial seawater buffered with 20 mM MES, HEPES or Tris, pH 6.5–10.5. Average motility at each pH (B) and time post-activation (C) is displayed. D shows a second-order polynomial regression for the effects of pH on sperm motility at 15 min post-activation. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 4). Treatments with different superscripts significantly differ (p < 0.05). A motility of 0% was indicated by asterisk.
Fig 4.
Effect of pH on sperm velocity (μm/s, A) in Eastern oyster, Crassostrea virginica. Sperm motility was assessed in artificial seawater buffered with 20 mM MES, HEPES or Tris, pH 6.5–10.5. Average motility at each pH (B) and time post-activation (C) is displayed. D shows a second-order polynomial regression for the effects of pH on sperm velocity at 15 min post-activation. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 4). Treatments with different superscripts significantly differ (p < 0.05). A velocity of 0 μm/s was indicated by asterisk.
Fig 5.
Effect of potassium (K+) ions on sperm motility (%, A-C) and velocity (μm/s, D-F) in Eastern oyster, Crassostrea virginica. Sperm was activated in K+-free artificial seawater (ASW) and ASW containing a voltage-gated (4-aminopyridine, 4-AP) or an ATP-sensitive (glybenclamide, G) K+ channel blocker. Average motility in each treatment (B) and time post-activation (C) is displayed. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 5). Treatments with different superscripts significantly differ (p < 0.05).
Fig 6.
Effect of calcium (Ca2+) ions on sperm motility (%, A-D) and velocity (μm/s, E-H) in Eastern oyster, Crassostrea virginica. Sperm was activated in artificial seawater (ASW), Ca2+-free ASW and ASW containing Ca2+ channel blockers: mibefradil (M), nifedipine (N), or verapamil (V). Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 4). Treatments with different superscripts significantly differ (p < 0.05). Motility of 0% and velocity of 0 μm/s were indicated by asterisk.
Fig 7.
Effect of sodium (Na+) ions on sperm motility (%, A-C) and velocity (μm/s, D-F) in Eastern oyster, Crassostrea virginica. Sperm was activated in artificial seawater (ASW), Na+-free ASW and Na+-free ASW or ASW containing Na+ channel blockers: amiloride (A). Motility and velocity with each treatment (B, E) and time post-activation (C, F) is displayed. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 5). Treatments with different superscripts significantly differ (p < 0.05).
Fig 8.
Effect of magnesium (Mg2+) ions on sperm motility (%, A-C) and velocity (μm/s, D-F) in Eastern oyster, Crassostrea virginica. Sperm was activated in artificial seawater (ASW) or Mg2+-free ASW. Motility and velocity with each treatment (B, E) and time post-activation (C, F) is displayed. Data were analyzed using a repeated measures ANOVA and shown as mean ± SE (n = 5). Treatments with different superscripts significantly differ (p < 0.05).