Shell differentiation and engrailed expression in the Ilyanassa embryo |
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Authors: | Sharon M Moshel Michael Levine J R Collier |
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Institution: | (1) Department of Biology, City University of New York, Brooklyn College, Brooklyn, New York 11210, USA, US;(2) Department of Molecular, Cell, and Developmental Biology, University of California, Berkeley, California, 94720-03422, USA, US |
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Abstract: | We have used in situ hybridization and immunocytochemistry to study the expression of the engrailed-related gene, Ily-en in embryos of the marine mud snail Ilyanassa obsoleta. We find that Ily-en is only expressed in shell gland cells. Only mRNAs localized in the shell gland hybridize to an antisense probe of the Ily-en homeobox. Similarly, only shell gland cells or shell-forming cells are stained by the monoclonal antibody 4D9, which was
raised to the engrailed-class protein from Drosophila. Ilyanassa embryos made deficient in vegetal cytoplasm by removing the third polar lobe fail to differentiate an organized external
shell. They do however make some randomly oriented internal shell fragments in which Ily-en is expressed. Because Ily-en is expressed in shell gland cells of both normal and lobeless embryos, we conclude that the determinant(s) required for Ily-en expression are not exclusively localized in the polar lobe.
Received: 16 October 1997 / Accepted: 9 January 1998 |
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Keywords: | Ilyanassa Shell differentiation Polar lobe Lobeless embryo Ily-engrailed |
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