A Study on the Role of Arylsulfatase in Sea Urchin Development

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In development of sea urchin embryos, the arylsulfatase activity begins to make a drastic increase at the mesenchyme blastula stage prior to the onset of gastrulation. The present research project has been undertaken to elucidate roles of arylsulfatase in the process of gastrulation. The following are the result of the two-years research project.(1) The arylsulfatase (Ars) gene of the embryo of the sea urchin, Hemicentrotus pulcherrimus, was cloned and its sequence was determined.(2) By in situ hybridization using anti-sense RNA of Ars-cDNA as the probe, it was found that the Ars gene is transcribed only in aboral ectoderm of sea urchin gastrula.(3) By the activity staining of arylsulfatase with optical as well as electron microscopes, it was found that arylulfatase localizes in lysosomes of qastrula, prism and pluteus larvae. It is suggested that arylsulfatase supplies sulfate ions through hydrolysis of yolk material which are needed to support gastrulation.(4) Addition of aphidicolin, an inhibitor of DNA synthesis, to sea urchin embryos resulted in the prevention of transcription of the Ars gene. The result was interpreted as that timing of the Ars gene transcription is somehow related to cycles of DNA replication after fertilization.