Worm Breeder's Gazette 11(1): 35
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.
We have been looking for steroid receptor homologues in C. elegans. To carry out this study two synthetic oligonucleotide probes (SR1 and SR2), based on sequences from the DNA-binding domain of various steroid receptors (see below), were used to screen a genomic library in lambda Charon 4. Four classes of phage, each carrying a distinct genomic insert, have been isolated and restriction mapped. Two were isolated using oligo SR1; the other two with SR2. Three show one or more bands on Northern blots of polyA+ RNA. One insert, from a phage isolated with SR1, was also used to screen a lambda ZAP cDNA library. A single positive clone contained a 2.2 kb insert. Partial sequence analysis of this cDNA reveals a 66 amino acid region having high homology to the DNA-binding domain of steroid receptor genes (see below). This sequence has been localized to the right end of the X chromosome by Alan Coulson, John Sulston et al. We are in the process of doing similar sequence analysis and genome localization for the other three phage classes. We are also trying to characterize putative finger protein clones, isolated by using an oligo from the H/C hinge consensus sequence. [See Figure 1] Completely conserved amino acid residues are indicated by asterisks between the C. elegans and human sequences. The amino acid sequences chosen for oligos SR1 and SR2 are indicated below. C. elegans codon usage was taken into account, making SR1 23nt and 32-fold degenerate, and SR2 20nt and 16-fold degenerate. The oligo sequences we chose were quite limited and probably less than ideal. Nevertheless we have isolated positive clones; these may be distinct from those isolated by Ann Sluder in the Ruvkin lab, given that she used different sequences to define oligo probes. Ce1, C. elegans homologue; h=human; ER, estrogen receptor; GR, glucocorticoid; MR, mineralocorticoid; PR, progesterone; VDR, vitamin D3; T3R, thyroid hormone.