Application of the cis ‐regulatory region of a heat‐shock protein 70 gene to heat‐inducible gene expression in the ascidian C iona intestinalis

Temporally controlled induction of gene expression is a useful technique for analyzing gene function. To make such a technique possible in Ciona intestinalis embryos, we employed the cis ‐regulatory region of the heat‐shock protein 70 (HSP70) gene Ci‐HSPA1/6/7 ‐ like for heat‐inducible gene expression in C. intestinalis embryos. We showed that Ci‐HSPA1/6/7 ‐ like becomes heat shock‐inducible by the 32‐cell stage during embryogenesis. The 5′‐upstream region of Ci‐HSPA1/6/7 ‐ like , which contains heat‐shock elements indispensable for heat‐inducible gene expression, induces the heat shock‐dependent expression of a reporter gene in the whole embryo from the 32‐cell to the middle gastrula stages and in progressively restricted areas of embryos in subsequent stages. We assessed the effects of heat‐shock treatments in different conditions on the normality of embryos and induction of transgene expression. We evaluated the usefulness of this technique through overexpression experiments on the well‐characterized, developmentally relevant gene, Ci‐Bra , and showed that this technique is applicable for inferring the gene function in C. intestinalis . genesis 53:170–182, 2015. © 2014 Wiley Periodicals, Inc.