1. A cell-free system capable of using oxygen with oxalacetate as substrate has been prepared from both unfertilized and fertilized sea urchin eggs. The oxygen uptake by this system is about twice that of an equivalent quantity of intact unfertilized eggs and half that of an equivalent quantity of intact fertilized eggs. 2. The oxygen consumption of this cell-free oxidative system can be stimul...

Early life-stage bioassays have been used as an alternative to short-term adult toxicity tests since they are cost-effective. A single couple can produce hundreds or thousands of embryos and hence can be used as a simple high-throughput approach in toxicity studies. In the present study, zebrafish and sea urchin embryo bioassays were used to test the toxicity of four pharmaceuticals belonging t...

Skeletogenesis in the sea urchin embryo is a simple model of biomineralization, pattern formation, and cell-cell communication during embryonic development. The calcium carbonate skeletal spicules are secreted by primary mesenchyme cells (PMCs), but the skeletal pattern is dictated by the embryonic ectoderm. Although the process of skeletogenesis is well characterized, there is little molecular...

Monoclonal antibody (SU5), prepared from isolated mitotic spindles of sea urchin eggs, stained centrospheres preferentially and recognized a 50K (K = 10(3) Mr) polypeptide on immunoblots. Three positive clones were isolated by screening a lambda gt11 cDNA expression library prepared from sea urchin egg mRNA with SU5. One clone containing a 1.8-kb (1 kb = 10(3) base-pairs) insert was selected fo...

Kinesin was previously immunolocalized to mitotic apparatuses (MAs) of early sea urchin blastomeres (Scholey, J.M., M.E. Porter, P.M. Grissom, and J.R. McIntosh. 1985. Nature [Lond.]. 318:483-486). Here we report evidence that this MA-associated motor protein is a conventional membrane-bound kinesin, rather than a kinesin-like protein. Our evidence includes the observation that the deduced amin...

Local cell-cell signals play a crucial role in establishing major tissue territories in early embryos. The sea urchin embryo is a useful model system for studying these interactions in deuterostomes. Previous studies showed that ectopically implanted micromeres from the 16-cell embryo can induce ectopic guts and additional skeletal elements in sea urchin embryos. Using a chimeric embryo approac...

Eric Davidson at Caltech has spent several decades investigating the molecular basis of animal development using the sea urchin embryo as an experimental system although his scholarship extends to all of embryology as embodied in several editions of his landmark book. In recent years his laboratory has become a leading force in constructing gene regulatory networks (GRNs) operating in sea urchi...

Echinoderms take many forms of symmetry. Pentameral symmetry is the major form and the other forms are derived from it. However, the ancestors of echinoderms, which originated from Cambrian period, were believed to be bilaterians. Echinoderm larvae are bilateral during their early development. During embryonic development of starfish and sea urchins, the position and the developmental sequence ...

This paper investigates the applicability of a simple hydrodynamics theory due to Gray & Hancock (1955), and extended by Brokaw (1970), to the analysis of the motions of sea urchin, rabbit, and bull spermatozoa. Experimental procedures for filming and analysing the swimming motions are presented. A detailed discussion of the agreement between the experimental and theoretical results is given, a...

The toxicity of three PCB congeners having different structural characteristics was studied using water exposures and the embryos of two sea urchin species, Strongylocentrotus purpuratus (purple sea urchin) and Lytechinus pictus (white sea urchin). Biological effects were assessed using two endpoints: percentage of normal embryo development and mitotic rate. Differential toxicity of the congene...