310
LIONEL F. JAFFE
directions would be correlated. This idea is illustrated in Fig. 11. A population of cell pairs showing a strong positive group effect is considered.
Whether or not the rhizin atmosphere about an isolated cell were polarized, the whole population of outgrowth directions would have the form
shown in the top row (Fig. 11). If impolarized, this same distribution
would be found independent of the source cell's axis (left column, Fig. 11)
but if polarized the distributions would be distorted toward correlation
with the source cell's axis (right column, Fig. 11). Note that one simple
indicator of such correlation would be a preponderance of cis as compared
to trans pairs, i.e., pairs with outgrowths toward the same as opposed to
the opposite side of the line joining their centers.
Recently large cell pair populations were examined for such correlation.
Two of the main findings are shown in Fig. 12. Under conditions giving a
strong positive group effect (when the cell pairs impose large rhizin
gradients upon each other), the pair axes are, indeed, strongly correlated.
However, under conditions giving a strong negative group effect (when
the cell interaction is dominated by antirhizin gradients), this correlation
is relatively weak. It can be inferred that each cell does, in fact, concentrate rhizin outside its own rhizoid pole.
It seems, then, that an extracellular rhizin gradient is a part of the
natural amplification system. Hence it might be possible to delay or
block polarization of the eggs by a sufficient disturbance of their relationship to the medium. In fact, Sussex (1967) reports preliminary evidence
(%)
+ 100
• 50
-50
-100
GROUP EFFECT
CORRELATION
CORRELATION
GAP IN EGG DIAMETERS
FIG. 12. Correlation of outgrowth directions of pairs of Fucus eggs. The upper two
curves indicate the mutual polarization of unwashed eggs cultured at pH 6; the
bottom two, that of vigorously washed eggs cultured at pH 8. (From Neuscheler and
Jaffe, unpublished.)
LIONEL F. JAFFE
directions would be correlated. This idea is illustrated in Fig. 11. A population of cell pairs showing a strong positive group effect is considered.
Whether or not the rhizin atmosphere about an isolated cell were polarized, the whole population of outgrowth directions would have the form
shown in the top row (Fig. 11). If impolarized, this same distribution
would be found independent of the source cell's axis (left column, Fig. 11)
but if polarized the distributions would be distorted toward correlation
with the source cell's axis (right column, Fig. 11). Note that one simple
indicator of such correlation would be a preponderance of cis as compared
to trans pairs, i.e., pairs with outgrowths toward the same as opposed to
the opposite side of the line joining their centers.
Recently large cell pair populations were examined for such correlation.
Two of the main findings are shown in Fig. 12. Under conditions giving a
strong positive group effect (when the cell pairs impose large rhizin
gradients upon each other), the pair axes are, indeed, strongly correlated.
However, under conditions giving a strong negative group effect (when
the cell interaction is dominated by antirhizin gradients), this correlation
is relatively weak. It can be inferred that each cell does, in fact, concentrate rhizin outside its own rhizoid pole.
It seems, then, that an extracellular rhizin gradient is a part of the
natural amplification system. Hence it might be possible to delay or
block polarization of the eggs by a sufficient disturbance of their relationship to the medium. In fact, Sussex (1967) reports preliminary evidence
(%)
+ 100
• 50
-50
-100
GROUP EFFECT
CORRELATION
CORRELATION
GAP IN EGG DIAMETERS
FIG. 12. Correlation of outgrowth directions of pairs of Fucus eggs. The upper two
curves indicate the mutual polarization of unwashed eggs cultured at pH 6; the
bottom two, that of vigorously washed eggs cultured at pH 8. (From Neuscheler and
Jaffe, unpublished.)