. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HOW A SPERM CLIMBS A HILL 99 AC/At [] B. Figure 4. Simulations of the ascidian model. (A) A sigmoid function as one of the examples of a function that positively correlates time-derived where T is the decay time constant. This condition was applied only when [Ca2 + ]j > c(p): otherwise, equation (6) was applied as before. When trajectories were calculated with these new sets of conditions (6, 6', 7), we found that the incorporation of a time component for the Ca2 + decay results in chemotactic trajectories (Fig. 3C
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. HOW A SPERM CLIMBS A HILL 99 AC/At [] B. Figure 4. Simulations of the ascidian model. (A) A sigmoid function as one of the examples of a function that positively correlates time-derived where T is the decay time constant. This condition was applied only when [Ca2 + ]j > c(p): otherwise, equation (6) was applied as before. When trajectories were calculated with these new sets of conditions (6, 6', 7), we found that the incorporation of a time component for the Ca2 + decay results in chemotactic trajectories (Fig. 3C) that are not unlike those obtained in the experimental observations. Likewise, chemotactic trajectories were reconstructed for a wide range of arbitrarily selected functions that relate 'c(p)' to l[Ca2 + ],' positively instead of by equation (6). and relate '[Ca21],' lo ';•(/)' negatively instead of by equation (7). even though some of them, of course, showed heavily distorted trajectories of approach toward the attractant source and unusually long or short times of approach. The ascidian model The behavior of ascidian sperm is quite different from that in the siphonophore sperm. The behavior illustrated in Figure IB is based on observations of Cioini intesti- imlix by Ishikawa (2000) and Yoshida et cil. (1993). In the presence of an attractant without a gradient, the curvature of the sperm trajectory is independent of the concentra- tion of the attractant. and is close to that in the absence of the attractant (Fig. IB). Under the gradient of attract- ant concentration, however, spermatozoa show rapid changes in their track diameters, so-called chemotactic turns. Since this turning behavior is lost in the calcium- free seawater (CFSW) or in the presence of Ca2+ channel inhibitors, it has been suggested that rapid changes of diameter are dependent on [Ca2 + ],. Therefore, we again incorporated condition (a), as we did in the siphonophore model. Next, we need to infer the rel
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
