Shell differentiation and engrailed expression in the Ilyanassa embryo

Sharon M. Moshel, Michael Levine, J. R. Collier

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)135-141
Number of pages7
JournalDevelopment Genes and Evolution
Issue number3
StatePublished - 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics
  • Developmental Biology


  • Ily-engrailed
  • Ilyanassa
  • Lobeless embryo
  • Polar lobe
  • Shell differentiation


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