310
JOHN RUNNSTRÖM
Eggs of Psammechinus
miliaris were inseminated and 10-20 sec later
transferred to 5 X 10~
4 M DNP. Despite this, the cortical changes went
on in an undisturbed way. This shows that even after attachment of the
spermatozoon the exposure to DNP does not have an immediate effect. It
was obvious that the reception cone is formed and also withdrawn in a
normal way (Runnström, 1963b). Parallel experiments were carried
out with transfer to 10~
4 KCN or 10~
3
Af iodoacetic acid. Also here the
cortical changes, including the formation and withdrawal of the reception
cone, took place. The further changes that require more elaborate movements and protein synthesis are stopped by DNP or KCN.
Ohnishi and Sugiyama (1963) made a Polarographie study of the
oxygen uptake in the eggs of Hemicentrotus
and Pseudocentrotus
immediately after fertilization. This method eliminates the disturbances
involved in manometric measurement in the period of strong acid
formation. They found that oxygen uptake had a lag time of about 1
min after sperm addition; acid formation, on the other hand, had no
measurable lag time. It is of interest that oxygen consumption is then
about fourteen times higher than in the unfertilized eggs. After 2-3
min more the oxygen uptake goes down to a rate three to four times
higher than in the unfertilized eggs. This indicates strongly that respiration starts in a stage of released control. Professor E. Scarano (personal
communication, 1963) demonstrated in Paracentrotus
lividus that the
quotient ADP/ATP increased following fertilization of the egg. This
agrees with the present interpretation of the data of the Japanese
workers as being due to a release of respiratory control. Thus the situation seems to be the following. A certain store of ATP is present in the
cortex of the sea urchin egg. This ATP is partially broken down to ADP
in order to provide energy for the cortical changes. This process in its
turn releases respiration from the controlled state prevailing in the unfertilized egg (Immers and Runnström, 1960). The strong compensating
rise in respiration starts a rather continuous formation of ATP that
provides, for example, the energy for protein synthesis initiated
only a few minutes after fertilization (T. Hultin and Bergstrand,
1960). The energy provided in the respiratory phase enables also
the building up of the system that is responsible for the uptake
of phosphate added to the medium. According to Whiteley and
Chambers (1960) this may be a protein of enzymatic nature. Its
formation is dependent on the opening of the cortical particles and the
release of the lamellae. Once this system has been established, its function as a mechanism of transport continues even in the presence of uncouples or respiration inhibitors (Griffiths and Whitely, 1964). From
the energetics point of view this is analogous to what has been reported
JOHN RUNNSTRÖM
Eggs of Psammechinus
miliaris were inseminated and 10-20 sec later
transferred to 5 X 10~
4 M DNP. Despite this, the cortical changes went
on in an undisturbed way. This shows that even after attachment of the
spermatozoon the exposure to DNP does not have an immediate effect. It
was obvious that the reception cone is formed and also withdrawn in a
normal way (Runnström, 1963b). Parallel experiments were carried
out with transfer to 10~
4 KCN or 10~
3
Af iodoacetic acid. Also here the
cortical changes, including the formation and withdrawal of the reception
cone, took place. The further changes that require more elaborate movements and protein synthesis are stopped by DNP or KCN.
Ohnishi and Sugiyama (1963) made a Polarographie study of the
oxygen uptake in the eggs of Hemicentrotus
and Pseudocentrotus
immediately after fertilization. This method eliminates the disturbances
involved in manometric measurement in the period of strong acid
formation. They found that oxygen uptake had a lag time of about 1
min after sperm addition; acid formation, on the other hand, had no
measurable lag time. It is of interest that oxygen consumption is then
about fourteen times higher than in the unfertilized eggs. After 2-3
min more the oxygen uptake goes down to a rate three to four times
higher than in the unfertilized eggs. This indicates strongly that respiration starts in a stage of released control. Professor E. Scarano (personal
communication, 1963) demonstrated in Paracentrotus
lividus that the
quotient ADP/ATP increased following fertilization of the egg. This
agrees with the present interpretation of the data of the Japanese
workers as being due to a release of respiratory control. Thus the situation seems to be the following. A certain store of ATP is present in the
cortex of the sea urchin egg. This ATP is partially broken down to ADP
in order to provide energy for the cortical changes. This process in its
turn releases respiration from the controlled state prevailing in the unfertilized egg (Immers and Runnström, 1960). The strong compensating
rise in respiration starts a rather continuous formation of ATP that
provides, for example, the energy for protein synthesis initiated
only a few minutes after fertilization (T. Hultin and Bergstrand,
1960). The energy provided in the respiratory phase enables also
the building up of the system that is responsible for the uptake
of phosphate added to the medium. According to Whiteley and
Chambers (1960) this may be a protein of enzymatic nature. Its
formation is dependent on the opening of the cortical particles and the
release of the lamellae. Once this system has been established, its function as a mechanism of transport continues even in the presence of uncouples or respiration inhibitors (Griffiths and Whitely, 1964). From
the energetics point of view this is analogous to what has been reported