LOCALIZATION IN THE DEVELOPING FUCUS EGG
311
that the polarization of fucaceous eggs grown in shake culture may be
substantially delayed.
3. Flow Effects
Analysis of the rheotropic responses of Fucus eggs may help understand the role of extracellular gradients in their polarization. Figure 13
shows the polarization of eggs by steady flow at various pH's. At pH 6.5
and at flow speeds of 0.01 (!) to 10 ^/second, they tend to germinate
downstream. From 0.01 to 1 /x/second, the degree of polarization at each
flow speed roughly equals the relative gradient that would be produced
by the convective redistribution of a substance of a diffusion constant of
the order of 10
8 cm
2
/second. It can be inferred that at pH 6.5, flow acts
by redistributing a locally effective growth stimulator which is emitted
Downstream
30+Upstream
FIG. 13. Polarization of Fucus eggs by steady flow. (From Bentrup and Jaffe,
1968).
— Per cent orientation (V,) —
311
that the polarization of fucaceous eggs grown in shake culture may be
substantially delayed.
3. Flow Effects
Analysis of the rheotropic responses of Fucus eggs may help understand the role of extracellular gradients in their polarization. Figure 13
shows the polarization of eggs by steady flow at various pH's. At pH 6.5
and at flow speeds of 0.01 (!) to 10 ^/second, they tend to germinate
downstream. From 0.01 to 1 /x/second, the degree of polarization at each
flow speed roughly equals the relative gradient that would be produced
by the convective redistribution of a substance of a diffusion constant of
the order of 10
8 cm
2
/second. It can be inferred that at pH 6.5, flow acts
by redistributing a locally effective growth stimulator which is emitted
Downstream
30+Upstream
FIG. 13. Polarization of Fucus eggs by steady flow. (From Bentrup and Jaffe,
1968).
— Per cent orientation (V,) —