Role of the Fyn Kinase in Calcium Release during Fertilization of the Sea Urchin Egg

The sea urchin egg has proved a reliable and robust system for measuring intracellular calcium release in response to three independent mechanisms: inositol 1,4,5 trisphosphate, cyclic ADP-ribose and the recently identified molecule, nicotinic acid adenine dinucleotide phosphate (NAADP). These calcium release mechanisms have been studied in homogenates of Lytechinus pictus and Spongylocentrotus purpuratus, which are two sea urchin species located off the west coast of the USA. A new calcium-release model from a species of sea urchin present off the coasts of Britain, Psammechinus miliaris is characterized and described. Although the Ca2+-release characteristics in this species do not differ from those of the other two sea urchin species, it may provide a more economical and convenient model for European scientists.

Download Full-text

A COMPARATIVE STUDY OF THE ISOLATION OF THE CORTEX AND THE ROLE OF THE CALCIUM-INSOLUBLE PROTEIN IN SEVERAL SPECIES OF SEA URCHIN EGG

The Journal of Cell Biology ◽

10.1083/jcb.41.1.133 ◽

1969 ◽

Vol 41 (1) ◽

pp. 133-144 ◽

Cited By ~ 32

Author(s):

R. E. Kane ◽

R. E. Stephens

Keyword(s):

Comparative Study ◽

Sea Urchin ◽

Protein Composition ◽

Cortical Region ◽

Cortical Granules ◽

Divalent Ions ◽

Sea Urchin Egg ◽

Protein Gelation ◽

Isolated Cortex

A comparative study was made of the isolation of the cortex in the eggs of several sea urchin species. Since the isolation method developed by Sakai depends on the presence of magnesium in the medium, the protein composition of the cortex was investigated to determine whether the protein component of the egg described by Kane and Hersh which is gelled by divalent ions, is present in these cortices. Isolation of the cortex was found to require the same divalent ions at the same concentrations as protein gelation, and in the eggs of some species much of the gel protein of the cell was found in the isolated cortical material. In the eggs of other species a smaller fraction of this protein was found in the isolated cortex, although it was more concentrated there than in the endoplasm, and in one species this protein appeared to be uniformly distributed throughout the cell. These results indicate that this protein is localized in the cortical region of the eggs of some species of sea urchin, possibly in the cortical granules, but also point up the fact that results from one species cannot be uncritically extrapolated to others.

Download Full-text

Biphasic Activation of Fyn Kinase upon Fertilization of the Sea Urchin Egg

Developmental Biology ◽

10.1006/dbio.1996.0073 ◽

1996 ◽

Vol 174 (2) ◽

pp. 281-287 ◽

Cited By ~ 43

Author(s):

William H. Kinsey

Keyword(s):

Sea Urchin ◽

Fyn Kinase ◽

Sea Urchin Egg

Download Full-text

Cortical localization of a calcium release channel in sea urchin eggs.

The Journal of Cell Biology ◽

10.1083/jcb.116.5.1111 ◽

1992 ◽

Vol 116 (5) ◽

pp. 1111-1121 ◽

Cited By ~ 76

Author(s):

S M McPherson ◽

P S McPherson ◽

L Mathews ◽

K P Campbell ◽

F J Longo

Keyword(s):

Sarcoplasmic Reticulum ◽

Ryanodine Receptor ◽

Sea Urchin ◽

Calcium Release ◽

Staining Pattern ◽

Cortical Granule ◽

Calcium Release Channel ◽

Release Channel ◽

Sea Urchin Eggs ◽

Sea Urchin Egg

We have used an antibody against the ryanodine receptor/calcium release channel of skeletal muscle sarcoplasmic reticulum to localize a calcium release channel in sea urchin eggs. The calcium release channel is present in less than 20% of immature oocytes, where it does not demonstrate a specific cytoplasmic localization, while it is confined to the cortex of all mature eggs examined. This is in contrast to the cortical and subcortical localization of calsequestrin in mature and immature eggs. Immunolocalization of the calcium release channel reveals a cortical reticulum or honeycomb staining network that surrounds cortical granules and is associated with the plasma membrane. The network consists of some immunoreactive electron-dense material coating small vesicles and elongate cisternae of the endoplasmic reticulum. The fluorescent reticular staining pattern is lost when egg cortices are treated with agents known to affect sarcoplasmic reticulum calcium release and induce cortical granule exocytosis (ryanodine, calcium, A-23187, and caffeine). An approximately 380-kD protein of sea urchin egg cortices is identified by immunoblot analysis with the ryanodine receptor antibody. These results demonstrate: (a) the presence of a ryanodine-sensitive calcium release channel that is located within the sea urchin egg cortex; (b) an altered calcium release channel staining pattern as a result of treatments that initiate the cortical granule reaction; and (c) a spatial and functional dichotomy of the ER which may be important in serving different roles in the mobilization of calcium at fertilization.

Download Full-text