Worm Breeder's Gazette 14(1): 37 (October 1, 1995)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
|1||Carnegie Institution of Washington, Department of Embryology|
|2||Biology Graduate Program, The Johns Hopkins University|
We have been studying the regulation of a gene, ceh-24, which encodes a novel homeodomain of the NK2 class. We are particularly interested in the ceh-24 expression pattern, since lacZ and gfp fusion experiments indicate that the promoter acts in specific subsets of muscle cells: muscle m8 of the pharynx and the vulval muscles (expression is also seen in 9-10 neurons in the head). We hope that precise identification of the signals responsible for expression in different muscle types will aid us in the identification of the mechanism responsible for setting muscle type during determination and differentiation. Translational fusions containing 2.85 kb of upstream ceh-24 sequence are sufficient for the complete expression pattern described above. The sequences responsible for both vulval and m8 reporter gene expression have been tentatively identified. The vulval signal has been narrowed down to a 83 bp fragment located 2 kb upstream of the ceh-24 start codon. This 83 bp fragment can activate a #198#pes-10::lacZ construct in vulval muscle (starting vector pPD95.18 - Fire Lab Vector Kit 1995). This occurs independent of any other ceh-24 sequence and works in either orientation. Deletion of this sequence in a complete ceh-24::gfp construct results in total loss of vulval gfp expression. This 83 bp fragment contains two identical E-boxes (CATATG) that have diverged from known E-boxes. E-boxes serve as binding sites for the helix-loop-helix (HLH) family of transcription factors. However, the C. elegans HLH-1 protein is not expressed in vulval muscle cells. The sequence responsible for m8 reporter expression has been narrowed down to a 270 bp fragment located 1.8 kb upstream of the ceh-24 start codon. This fragment can also work independent of any other ceh-24 sequence [assayed in a #198#myo-2 promoter construct (pPD95.62 - Fire Lab Vector Kit 1995)].