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We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with(More)
  • David Epel
  • Cell differentiation and development : the…
  • 1990
As seen, important advances have now been made in understanding the beginning of development at fertilization. Free calcium and pHi level changes result from a sperm-mediated breakdown of PPI with production of IP3. The resultant calcium increase, either alone or in concert with diacylglycerol, activates the Na(+)-H+ exchange and a consequent cytosolic pHi(More)
Metazoan genomes contain large numbers of genes that participate in responses to environmental stressors. We surveyed the sea urchin Strongylocentrotus purpuratus genome for homologs of gene families thought to protect against chemical stressors; these genes collectively comprise the 'chemical defensome.' Chemical defense genes include cytochromes P450 and(More)
Contrary to the view that embryos and larvae are the most fragile stages of life, development is stable under real-world conditions. Early cleavage embryos are prepared for environmental vagaries by having high levels of cellular defenses already present in the egg before fertilization. Later in development, adaptive responses to the environment either(More)
The early steps that lead to the rise in calcium and egg activation at fertilization are unknown but of great interest--particularly with the advent of in vitro fertilization techniques for treating male infertility and whole-animal cloning by nuclear transfer. This calcium rise is required for egg activation and the subsequent events of development in eggs(More)
Intracellular pH (pH1) of sea urchin eggs and embryos was determined using DMO (5,5-dimethyl-2,4-oxazolidinedione). By this method, the pH1 of Lytechinus pictus eggs increased after fertilization from 6.86 to 7.27, and this higher pHi was maintained thereafter, as has been previously observed with pH microelectrodes. The same general result was obtained(More)
Micromolar amounts of the divalent ionophore A23187 can activate echinoderm eggs. The activations by ionophore A23187 were examined in terms of membrane elevation, the program of membrane conductance changes, the respiratory burst, and the increases in protein and DNA synthesis which normally accompany activation by sperm. In all these respects activation(More)