Tension at the Surface of the Dividing Sea-Urchin Egg

1972 ◽  
Vol 57 (3) ◽  
pp. 575-587 ◽  
Author(s):  
MITSUKI YONEDA ◽  
KATSUMA DAN
Keyword(s):  
Sea Urchin ◽  
Computer Method ◽  
Sharp Peak ◽  
Compression Method ◽  
Sea Urchin Egg ◽  
Cyclic Changes

1. Cyclic changes in tension correlating with the division cycle were demonstrated by compression method of Cole. 2. A sharp peak in the tension was found 8 min before the onset of cleavage at 13°C 3. A computer method indicated that the tension reached a maximum at the start of cleavage, after which it steadily decreased throughout the course of cleavage. 4. A rough estimation revealed that the force of constriction at the equatorial ring amounted to 6 x 10-3 dyne, which compares well with Rappaport's result (1967).

Tension at the Surface of Sea-Urchin Egg: A Critical Examination of Cole's Experiment

1964 ◽  
Vol 41 (4) ◽  
pp. 893-906 ◽  
Author(s):  
MITSUKI YONEDA
Keyword(s):  
Surface Area ◽  
Sea Urchin ◽  
Contact Area ◽  
Surface Force ◽  
Critical Examination ◽  
Compression Method ◽  
Osmotic Swelling ◽  
Technical Errors ◽  
Sea Urchin Egg ◽  
Hemicentrotus Pulcherrimus

1. The compression method for calculating the surface force of the sea-urchin egg, developed by Cole (1932), has been critically repeated using unfertilized eggs of Hemicentrotus pulcherrimus. 2. Estimation of contact area involved in Cole's equation introduces technical errors. 3. The tension recalculated by another equation including surface area as a parameter is found to remain constant irrespective of change in surface area. This is in conflict with the classical belief that the cortex of the egg of sea urchin is elastic. 4. Neither osmotic swelling nor osmotic shrinkage of the egg affects the tension.

scholarly journals Different Ca2+-releasing abilities of sperm extracts compared with tissue extracts and phospholipase C isoforms in sea urchin egg homogenate and mouse eggs

2000 ◽  
Vol 346 (3) ◽  
pp. 743-749 ◽  
Author(s):  
Keith T. JONES ◽  
Miho MATSUDA ◽  
John PARRINGTON ◽  
Matilda KATAN ◽  
Karl SWANN
Keyword(s):  
Phospholipase C ◽  
Sea Urchin ◽  
Tissue Extracts ◽  
Sea Urchin Egg ◽  
Boar Sperm ◽  
Specific Activities ◽  
Mammalian Eggs ◽  
Mouse Eggs

A soluble phospholipase C (PLC) from boar sperm generates InsP3 and hence causes Ca2+ release when added to sea urchin egg homogenate. This PLC activity is associated with the ability of sperm extracts to cause Ca2+ oscillations in mammalian eggs following fractionation. A sperm PLC may, therefore, be responsible for causing the observed Ca2+ oscillations at fertilization. In the present study we have further characterized this boar sperm PLC activity using sea urchin egg homogenate. Consistent with a sperm PLC acting on egg PtdIns(4,5)P2, the ability of sperm extracts to release Ca2+ was blocked by preincubation with the PLC inhibitor U73122 or by the addition of neomycin to the homogenate. The Ca2+-releasing activity was also detectable in sperm from other species and in whole testis extracts. However, activity was not observed in extracts from other tissues. Moreover recombinant PLCβ1, -γ1, -γ2, -∆1, all of which had higher specific activities than boar sperm extracts, were not able to release Ca2+ in the sea urchin egg homogenate. In addition these PLCs were not able to cause Ca2+ oscillations following microinjection into mouse eggs. These results imply that the sperm PLC possesses distinct properties that allow it to hydrolyse PtdIns(4,5)P2 in eggs.

ACID-SOLUBLE NUCLEOTIDES IN THE SEA URCHIN EGG

Embryologia ◽  
1966 ◽  
Vol 9 (3) ◽  
pp. 170-183 ◽  
Author(s):  
TOMIO YANAGISAWA ◽  
NAOHIDE ISONO
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Egg
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