282
JOHN RUNNSTRÖM
a striking contrast to the experiment with hyaline layer substance. Porphyrexid exerts its inhibitory action on the vitelline membrane, whereas
the fertilization of trypsin-treated eggs or denuded fertilized eggs is not
inhibited by porphyrexid (Runnström, 1957; Runnström and Kriszat,
1957).
Lundblad and Lundblad (1962) showed in their work, referred to in
Sections II,D and E, that homogenized unfertilized eggs of
Paracentrotus
deprived of their jelly coat after dialysis gave a chromatographic pattern
on DEAE-Sephadex which included the high peak I of Fig. 24A. When
dialyzed homogenates of eggs were used, in which the jelly coat was not
removed, peak I was absent. This could mean that the acid jelly coat has
reacted with the proteins of peak I. The complex formed becomes more
acid in character than the material of jellyless eggs. As a consequence,
the complex constituted by peak I material and jelly coat does not pass
through the DEAE-Sephadex column. This proves that, under suitable
circumstances, the jelly coat substance is able to react with the proteins
belonging to peak I. As mentioned in Section ΙΙ,Ε, peak I is the main
carrier of proteolytic enzymes in the unfertilized eggs. In this way,
it seems very probable that jelly coat substance is an inhibitor of normal
fertilization because it reacts with the fraction containing proteolytic
enzymes; this may be one of the reasons for the impairment of the
normal course of cortical changes after insemination of the eggs exposed
to dissolved jelly coat substance. The proteins covering the egg surface
may contain proteolytic enzymes. The inhibitory effect of the jelly coat
substance could depend on its combination with proteins in the egg surface and the proteolytic enzymes contained in them. Lundblad (1954)
showed that the activity of Ε 2, the first of the enzymes Ε 1-E 3 to be
activated on fertilization, is inhibited by heparin. Under normal conditions, the gelating effect of Ε 2 around the spermatozoon may bring
about a certain concentration of the superficial protein layer toward
the site of attachment of the spermatozoon. This may constitute a link
in the reception of the spermatozoon which fixes the tip of the acrosomal
tubule more firmly to the cytoplasmic surface. The next step will then
be the fusion of the plasma membranes of the male and the female
gamete which initiates the zygote formation.
The importance of the outer protein layer in the plasma membrane
for the reception of the spermatozoon explains also why trypsin in concentration above 1 X 10~
4
% may decrease the number of fertilized eggs
without any detrimental effect on artificial activation (Section II,D).
Wicklund et al. (1953) found that addition of certain inhibitors of fertilization bring about a change in the physical state of the egg surface.
On centrifugation of the treated eggs, at the border between sea water
JOHN RUNNSTRÖM
a striking contrast to the experiment with hyaline layer substance. Porphyrexid exerts its inhibitory action on the vitelline membrane, whereas
the fertilization of trypsin-treated eggs or denuded fertilized eggs is not
inhibited by porphyrexid (Runnström, 1957; Runnström and Kriszat,
1957).
Lundblad and Lundblad (1962) showed in their work, referred to in
Sections II,D and E, that homogenized unfertilized eggs of
Paracentrotus
deprived of their jelly coat after dialysis gave a chromatographic pattern
on DEAE-Sephadex which included the high peak I of Fig. 24A. When
dialyzed homogenates of eggs were used, in which the jelly coat was not
removed, peak I was absent. This could mean that the acid jelly coat has
reacted with the proteins of peak I. The complex formed becomes more
acid in character than the material of jellyless eggs. As a consequence,
the complex constituted by peak I material and jelly coat does not pass
through the DEAE-Sephadex column. This proves that, under suitable
circumstances, the jelly coat substance is able to react with the proteins
belonging to peak I. As mentioned in Section ΙΙ,Ε, peak I is the main
carrier of proteolytic enzymes in the unfertilized eggs. In this way,
it seems very probable that jelly coat substance is an inhibitor of normal
fertilization because it reacts with the fraction containing proteolytic
enzymes; this may be one of the reasons for the impairment of the
normal course of cortical changes after insemination of the eggs exposed
to dissolved jelly coat substance. The proteins covering the egg surface
may contain proteolytic enzymes. The inhibitory effect of the jelly coat
substance could depend on its combination with proteins in the egg surface and the proteolytic enzymes contained in them. Lundblad (1954)
showed that the activity of Ε 2, the first of the enzymes Ε 1-E 3 to be
activated on fertilization, is inhibited by heparin. Under normal conditions, the gelating effect of Ε 2 around the spermatozoon may bring
about a certain concentration of the superficial protein layer toward
the site of attachment of the spermatozoon. This may constitute a link
in the reception of the spermatozoon which fixes the tip of the acrosomal
tubule more firmly to the cytoplasmic surface. The next step will then
be the fusion of the plasma membranes of the male and the female
gamete which initiates the zygote formation.
The importance of the outer protein layer in the plasma membrane
for the reception of the spermatozoon explains also why trypsin in concentration above 1 X 10~
4
% may decrease the number of fertilized eggs
without any detrimental effect on artificial activation (Section II,D).
Wicklund et al. (1953) found that addition of certain inhibitors of fertilization bring about a change in the physical state of the egg surface.
On centrifugation of the treated eggs, at the border between sea water