Expression and sequence analysis of the Drosophila blastoderm-specific gene bsg25A.

By differential screening of a genomic library, we have cloned a gene expressed specifically during the blastoderm stage of Drosophila embryogenesis. Northern blot analysis and in situ hybridization to embryos reveal that the transcript is maximally expressed during the late syncytial blastoderm stage, disappears rapidly during the cellular blastoderm stage and is not detected at any other point in the Drosophila life cycle. On the basis of its temporally restricted expression and its polytene chromosomal map position at 25A1,2, we have designated this gene blastoderm-specific gene 25A (bsg25A). bsg25A encodes a novel protein of 23 kDa.