Worm Breeder's Gazette 17(1): 62 (October 1, 2001)
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.
Department of Biology, University of Fribourg, Ch. du Musée 10, 1700 Fribourg, Switzerland
The C. elegans labial/Hox1 type gene ceh-13 , in contrast to some other members of the C. elegans Hox cluster, is required for viability, in particular for proper organization of anterior structures during embryogenesis1. Since spaciotemporal ceh-13 expression appears to be controlled at the level of transcription1,2 we have undertaken a deletional and mutational promoter analysis3. In order to complement these earlier studies we have cloned and preliminarily sequenced the ceh-13 ortholog from C. remanei (Cr-ceh-13) and compared its sequence with Ce-ceh-13 and with ceh-13 from C. briggsae (Cb-ceh-13) that has recently been sequenced by the C. briggsae sequencing consortium. The intron exon structure of ceh-13 is conserved in all three species. At the amino acid level the overall identities / similarities are 77% / 80% for Ce-ceh-13 and Cb-ceh-13, 81% / 87% for Ce-ceh-13 and Cr-ceh-13 and 83% / 86% for Cb-ceh-13 and Cr-ceh-13 (Fig. 1). Not surprisingly the homeodomain is 100% conserved between the three species.
A Ce-ceh-13:: gfp reporter construct (pMF12) that reflects ceh-13 expression very well at all developmental stages tested, appears to be correctly controlled also in C. briggsae. Therefore we expected to find conserved elements also in non-coding regions.
Indeed, in a preliminary analysis we found short conserved stretches that might be regulatory elements. Interestingly, the three most obvious ones are located in regions that had previously been shown to be important for the control of Ce-ceh-13 expression. A first element with 26 bp that are identical in all three species is located in a region of 400bp that is sufficient to confer ceh-13 like expression to GFP in, among other places, the male tail. A second element with 15 bp out of 16 bp that are identical in all three species lies within a fragment of 740bp that is sufficient to drive correct early embryonic ceh-13expression3. Finally there is a stretch of 15 identical bp that resides within intron 1. From earlier studies we suspect that intron 1 is required to prevent ceh-13 expression in adult body wall muscles4. We are currently performing mutational analyses to test the significance of these findings.
Fig. 1: Comparison of the predicted CEH-13 amino acid sequences from the three Caenorhabditis species. The 100% conserved homeodomain is underlined; amino acids that are identical in all three species are in bold.
1) Brunschwig et al. (1999) Development 126:1537-1546
2) Wittmann et al. (1997) Development 124:4193-41200
3) Streit et al. submitted
4) Reto Kohler (1999) Ph.D. thesis, University of Fribourg.