312
JOHN RUNNSTRÖM
reaction of Ca
2+ with phospholipids is assumed to give rise to continued
production of H
+ . Similar reactions may play a subsidiary role in the
sea urchin egg, where the main source of acid production is the depolymerization of sulfated polysaccharides (Section H,B), which may form
anions to balance the cation Ca
2 +
.
A Ca
2+ uptake by ion exchange into the cortical particles may cause
the swelling of its matrix; the simultaneous contraction of the surrounding ground cytoplasm (Section II,C) may also be Ca
2 +
-dependent. The
results with DNP indicate that these processes are also ATP-dependent.
Furthermore, Ca
2+ is necessary for the sliding movements of the lamellae
in contact with the vitelline membrane. The inclusion of the filling
material in the fertilization membrane (Section III,C) is a Ca
2 +
- and
probably also ATP-dependent process.
Mersalyl or salyrgan is an inhibitor of the Ca
2 +
-activated ATPase in
muscle (see Weber and Portzehl, 1954). When the eggs are pretreated
with mersalyl in concentrations of 10~
4
-10~
6
Af, the eggs show a considerable polyspermy on insemination (Runnström and Manelli, 1964).
The polyspermy-promoting effect of mersalyl cannot be referred to events
at the light-microscopic level. The active protection against polyspermy
seems to be associated with the opening of the cortical particles and the
release of its matrix from the hollows. The large concavities which reflect
a wide opening of the cortical hollows appear also in the mersalyl-pretreated eggs. Manelli and Runnström (unpublished results, 1964) examined by means of electron microscopy the question of whether the
displacement of the extralamellar bodies and their conversion to a
boundary of the hyaline layer would be delayed or modified following
mersalyl treatment. Although the results did not exclude this possibility,
they were not decisive because of the great variability prevailing also
in the control eggs. The low concentrations at which mersalyl is active
indicate that it reacts in a rather specific way with a critical SH-compound present in the cortex of the egg.
C. Shifts in Enzyme Activity
After the cortical changes are accomplished, the egg assumes a
spherical shape. This may be a process analogous to relaxation of a
muscle cell. At this period or earlier, Ca
2+ is bound to endoplasmic
vesicles (see Hasselbalch and Makinose, 1961; Ohnishi and Ebashi,
1964). It may be significant that a phase is formed below the site of
reception of the spermatozoon that is rich in endoplasmic vesicles
(Section IV,D). The contraction and relaxation may be bound to
the contractile elements which Sakai (1960a,b) obtained from proteins
extracted with KCl solution from the eggs or isolated cortical layers
JOHN RUNNSTRÖM
reaction of Ca
2+ with phospholipids is assumed to give rise to continued
production of H
+ . Similar reactions may play a subsidiary role in the
sea urchin egg, where the main source of acid production is the depolymerization of sulfated polysaccharides (Section H,B), which may form
anions to balance the cation Ca
2 +
.
A Ca
2+ uptake by ion exchange into the cortical particles may cause
the swelling of its matrix; the simultaneous contraction of the surrounding ground cytoplasm (Section II,C) may also be Ca
2 +
-dependent. The
results with DNP indicate that these processes are also ATP-dependent.
Furthermore, Ca
2+ is necessary for the sliding movements of the lamellae
in contact with the vitelline membrane. The inclusion of the filling
material in the fertilization membrane (Section III,C) is a Ca
2 +
- and
probably also ATP-dependent process.
Mersalyl or salyrgan is an inhibitor of the Ca
2 +
-activated ATPase in
muscle (see Weber and Portzehl, 1954). When the eggs are pretreated
with mersalyl in concentrations of 10~
4
-10~
6
Af, the eggs show a considerable polyspermy on insemination (Runnström and Manelli, 1964).
The polyspermy-promoting effect of mersalyl cannot be referred to events
at the light-microscopic level. The active protection against polyspermy
seems to be associated with the opening of the cortical particles and the
release of its matrix from the hollows. The large concavities which reflect
a wide opening of the cortical hollows appear also in the mersalyl-pretreated eggs. Manelli and Runnström (unpublished results, 1964) examined by means of electron microscopy the question of whether the
displacement of the extralamellar bodies and their conversion to a
boundary of the hyaline layer would be delayed or modified following
mersalyl treatment. Although the results did not exclude this possibility,
they were not decisive because of the great variability prevailing also
in the control eggs. The low concentrations at which mersalyl is active
indicate that it reacts in a rather specific way with a critical SH-compound present in the cortex of the egg.
C. Shifts in Enzyme Activity
After the cortical changes are accomplished, the egg assumes a
spherical shape. This may be a process analogous to relaxation of a
muscle cell. At this period or earlier, Ca
2+ is bound to endoplasmic
vesicles (see Hasselbalch and Makinose, 1961; Ohnishi and Ebashi,
1964). It may be significant that a phase is formed below the site of
reception of the spermatozoon that is rich in endoplasmic vesicles
(Section IV,D). The contraction and relaxation may be bound to
the contractile elements which Sakai (1960a,b) obtained from proteins
extracted with KCl solution from the eggs or isolated cortical layers