276
JOHN RUNNSTRÖM
fertilized and fertilized eggs (see Öhman, loc. cit.). Runnström (1958)
found that blister formation occurs also in fertilized eggs that have been
fixed in 4% neutral formaldehyde. In unfertilized eggs, blister formation
is negligible ; in eggs that had been fixed at a stage in which the fertilization membrane had been only partially formed, the blisters appeared in
the region of the egg surface that was covered by the fertilization membrane. When the membrane was formed over the whole surface of the
egg, lipoprotein-containing blisters appeared also in the distal region,
but they often appeared denser here than in the proximal region. Reference was earlier made (Section II,C) to the probable connection between changes in the plasma membrane, the membrane of the cortical
particles, and the endoplasmic membranes.
E. Molecular Rearrangement after Fertilization of the Egg
Investigations on living sea urchin eggs with dark-field illumination
combined with experimental procedures, prompted Runnström (1928a,b,
reviewed 1949) to outline certain ideas about the rearrangement of
molecules in the egg following fertilization. Mirsky (1936) and Monroy
and Monroy-Oddo (1951) studied changes in the solubilities of proteins
upon fertilization. One fraction contained in the material, extracted with
1 M KCl from unfertilized eggs, seems to become insoluble after fertilization (the "Mirsky protein"). The field has been reviewed by Monroy
(1957b) to whom the reader is referred.
In this section some results will be briefly mentioned that have been
obtained by Lundblad and Lundblad (1962) and are illustrated in Figs.
24A and B. A volume of jelly-free eggs from Paracentrotus
was mixed
with an equal volume of 0.04 M
tris(hydroxymethyl)aminomethane
(Tris) buffer, pH 7.4. The suspension was then homogenized; the homogenate was submitted to centrifugation for 12 min at 10,000 g in order to
remove the coarser particles. After dialysis against 0.02 M Tris buffer
the homogenate was subjected to anion-exchange chromatography on
columns of diethylaminoethyl (DEAE)-Sephadex A-25. The elution
was made with increasing NaCl concentrations; the extinction of the
eluates was determined at 260 and 280 πΐμ. When comparing the curves in
Figs. 24A and B, it was found that Fraction I, which gives a very high
extinction in the unfertilized eggs, was strongly reduced in eggs homogenized 10 min after insemination. A great part of Fraction I from fertilized eggs did not pass through the column, possibly because the material had become of a more acid character. Peak I in the homogenates
of unfertilized eggs had a strong orange color which in homogenates of
fertilized eggs is found in Fraction V. Likewise, the cathepsin Β activity
JOHN RUNNSTRÖM
fertilized and fertilized eggs (see Öhman, loc. cit.). Runnström (1958)
found that blister formation occurs also in fertilized eggs that have been
fixed in 4% neutral formaldehyde. In unfertilized eggs, blister formation
is negligible ; in eggs that had been fixed at a stage in which the fertilization membrane had been only partially formed, the blisters appeared in
the region of the egg surface that was covered by the fertilization membrane. When the membrane was formed over the whole surface of the
egg, lipoprotein-containing blisters appeared also in the distal region,
but they often appeared denser here than in the proximal region. Reference was earlier made (Section II,C) to the probable connection between changes in the plasma membrane, the membrane of the cortical
particles, and the endoplasmic membranes.
E. Molecular Rearrangement after Fertilization of the Egg
Investigations on living sea urchin eggs with dark-field illumination
combined with experimental procedures, prompted Runnström (1928a,b,
reviewed 1949) to outline certain ideas about the rearrangement of
molecules in the egg following fertilization. Mirsky (1936) and Monroy
and Monroy-Oddo (1951) studied changes in the solubilities of proteins
upon fertilization. One fraction contained in the material, extracted with
1 M KCl from unfertilized eggs, seems to become insoluble after fertilization (the "Mirsky protein"). The field has been reviewed by Monroy
(1957b) to whom the reader is referred.
In this section some results will be briefly mentioned that have been
obtained by Lundblad and Lundblad (1962) and are illustrated in Figs.
24A and B. A volume of jelly-free eggs from Paracentrotus
was mixed
with an equal volume of 0.04 M
tris(hydroxymethyl)aminomethane
(Tris) buffer, pH 7.4. The suspension was then homogenized; the homogenate was submitted to centrifugation for 12 min at 10,000 g in order to
remove the coarser particles. After dialysis against 0.02 M Tris buffer
the homogenate was subjected to anion-exchange chromatography on
columns of diethylaminoethyl (DEAE)-Sephadex A-25. The elution
was made with increasing NaCl concentrations; the extinction of the
eluates was determined at 260 and 280 πΐμ. When comparing the curves in
Figs. 24A and B, it was found that Fraction I, which gives a very high
extinction in the unfertilized eggs, was strongly reduced in eggs homogenized 10 min after insemination. A great part of Fraction I from fertilized eggs did not pass through the column, possibly because the material had become of a more acid character. Peak I in the homogenates
of unfertilized eggs had a strong orange color which in homogenates of
fertilized eggs is found in Fraction V. Likewise, the cathepsin Β activity