scholarly journals Identification of a sperm receptor on the surface of the eggs of the sea urchin Arbacia punctulata.

1977 ◽  
Vol 72 (1) ◽  
pp. 35-46 ◽  
Author(s):  
E Schmell ◽  
B J Earles ◽  
C Breaux ◽  
W J Lennarz
Keyword(s):  
Sea Urchin ◽  
Concanavalin A ◽  
Strongylocentrotus Purpuratus ◽  
Soluble Form ◽  
Ionophore A23187 ◽  
Soluble Receptor ◽  
Specific Receptor ◽  
Marked Contrast ◽  
Arbacia Punctulata ◽  
Species Specific

The possibility that the surface of the egg of the sea urchin Arbacia punctulata contains a species-specific receptor for sperm has been investigated. The extent of fertilization of eggs of A. punctulata, which is proportional to the number of sperm, is unaffected by the presence of either eggs or membranes prepared from eggs of Strongylocentrotus purpuratus. In marked contrast, membranes prepared from eggs of A. punctulata quantitatively inhibit fertilization of A. punctulata eggs by A. punctulata sperm. Several lines of evidence indicate that this inhibition is due to the presence of a membrane-associated glycoprotein that binds to the sperm, thus preventing them from interacting with receptor on the surface of the eggs. First, eggs treated with trypsin are incapable of being fertilized, although they can be activated with the Ca2+ ionophore A23187. Moreover, membranes prepared from eggs pretreated with trypsin do not inhibit fertilization of eggs. Second, receptor isolated in soluble form from surface membranes binds to sperm and thus prevents them from fertilizing eggs; the inhibition by soluble receptor is species-specific. Third, the soluble receptor binds to concanavalin A-Sepharose. Fourth, eggs are incapable of being fertilized if they are pretreated with concanavalin A. The specificity of inhibition, and the affect of trypsin and concanavalin A on intact eggs, suggest that the receptor is a species-specific macromolecule located on the surface of the eggs. The sensitivity of the receptor to trypsin, and its ability to bind to concanavalin A, indicate that it is a glycoprotein.

scholarly journals Sea urchin tube feet: unique structures that allow a cytological and molecular approach to the study of actin and its gene expression.

1981 ◽  
Vol 89 (1) ◽  
pp. 109-114 ◽  
Author(s):  
J Kabat-Zinn ◽  
R H Singer
Keyword(s):  
Sea Urchin ◽  
Gel Electrophoresis ◽  
Messenger Rna ◽  
Strongylocentrotus Purpuratus ◽  
Strongylocentrotus Droebachiensis ◽  
Blue Staining ◽  
Phage Library ◽  
Two Dimensional ◽  
Arbacia Punctulata ◽  
Tube Feet

Actin is the major extractable protein component from the tube feet of four different species of sea urchin: Arbacia punctulata, Strongylocentrotus purpuratus, Strongylocentrotus droebachiensis, and Diadema setosum. Actin made up as much as 60% of the total Coomassie Blue-staining material after SDS polyacrylamide gel electrophoresis and densitometer analysis. Two-dimensional gel electrophoresis resolved two, and possible three, species of actin for each sea urchin of which the dominant component was analogous to the beta form in vertebrates. In a cell-free system from rabbit reticulocytes, total RNA from tube feet stimulated the synthesis of one protein that represented 80% of the total methionine incorporation, migrated with the properties characteristic of actin in a two-dimensional gel system, and on proteolysis yielded fragments identical to purified rabbit actin. The mRNAs from the tube feet of two divergent species of sea urchin, Arbacia punctulata and Strongylocentrotus purpuratus, synthesized actins differing by less than 0.02 pH unit for each isospecies 90% of the DNA copied from tube foot RNA by reverse transcriptase represented a highly abundant sequence class judged by copy DNA(cDNA)-RNA excess hybridization. At least two-thirds of this class represented a low-complexity component, with a Rot1/2 about three times that expected for actin messenger RNA. The remarkable degree of conservation of the actin protein is reflected in concomitant conservation of the protein-coding nucleotide sequences of the messenger RNA, which has allowed the use of a cDNA probe to isolate actin sequences from a human phage library.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

Autonomous and non-autonomous differentiation of ectoderm in different sea urchin species

Development ◽  
1995 ◽  
Vol 121 (5) ◽  
pp. 1497-1505 ◽  
Author(s):  
A.H. Wikramanayake ◽  
B.P. Brandhorst ◽  
W.H. Klein
Keyword(s):  
Sea Urchin ◽  
Strongylocentrotus Purpuratus ◽  
Protein A ◽  
Cellular Interactions ◽  
V Protein ◽  
Lytechinus Pictus ◽  
Sea Urchin Embryo ◽  
Oral Ectoderm ◽  
Temporal And Spatial

During early embryogenesis, the highly regulative sea urchin embryo relies extensively on cell-cell interactions for cellular specification. Here, the role of cellular interactions in the temporal and spatial expression of markers for oral and aboral ectoderm in Strongylocentrotus purpuratus and Lytechinus pictus was investigated. When pairs of mesomeres or animal caps, which are fated to give rise to ectoderm, were isolated and cultured they developed into ciliated embryoids that were morphologically polarized. In animal explants from S. purpuratus, the aboral ectoderm-specific Spec1 gene was activated at the same time as in control embryos and at relatively high levels. The Spec1 protein was restricted to the squamous epithelial cells in the embryoids suggesting that an oral-aboral axis formed and aboral ectoderm differentiation occurred correctly. However, the Ecto V protein, a marker for oral ectoderm differentiation, was detected throughout the embryoid and no stomodeum or ciliary band formed. These results indicated that animal explants from S. purpuratus were autonomous in their ability to form an oral-aboral axis and to differentiate aboral ectoderm, but other aspects of ectoderm differentiation require interaction with vegetal blastomeres. In contrast to S. purpuratus, aboral ectoderm-specific genes were not expressed in animal explants from L. pictus even though the resulting embryoids were morphologically very similar to those of S. purpuratus. Recombination of the explants with vegetal blastomeres or exposure to the vegetalizing agent LiCl restored activity of aboral ectoderm-specific genes, suggesting the requirement of a vegetal induction for differentiation of aboral ectoderm cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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