Worm Breeder's Gazette 12(3): 77 (June 15, 1992)
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.
Using the screening method described previously, (Hope (1991), Development 113, 399-408 and WBG vol. 11#4,p.58), the single plasmids responsible for a further six LacZ expression patterns have been identified. Large pools of independent plasmid constructs containing random fragments of C. elegans genomic DNA upstream of LacZ were initially used to transform C. elegans. Pools with active constructs (those which show an expression pattern) were selected and the pool sizes decreased until the active plasmid was located.
l) p UL#25 C4of pool 25. ß-galactosidase expression in the head ganglion, vulva, preanal ganglion and along the ventral nerve cord, first appearing in the late embryo. The staining neurones could be descendants of the 12 P cells. This plasmid hybridizes to Y70G4 (LGIV) on a YAC polytene grid and has been placed on the physical map by Alan Coulson.
2)p UL#26 D10of pool 26. Expression is nuclear localized in the 3 cells of the rectal epithelium, which form a ring situated posteriorly to the intestinal-rectal valve, and throughout the pharynx. Pharyngeal staining is probably an artefact due to the presence of an incomplete promoter.
3)p UL#38 ESof pool 38. Staining is seen throughout embryos possibly as early as the 2 cell stage. The stage at which expression ends has not yet been determined.
4)p UL#38 E12of pool 38. Expression is primarily seen in the spermathecal valves (L3/4 to adult) and the intestinal-rectal valve (late embryo to adult). As pool sizes decreased diffuse staining appeared in the gonad, from the vulva outwards, particularly during gonad formation. Initial hybridization to a YAC polytene grid detected many clusters of YACs indicating that a repetitive sequence is present within the plasmid insert. An integrated line has been obtained with this plasmid, but when used in a pool with 4 other, nonexpressing, plasmids.
S)p UL#64 A1of pool 64. Initially this pattern was seen as staining of the excretory cell. As pool size was reduced both anterior and posterior branches of the excretory cell could be clearly seen from late embryo onwards. Furthermore, hypodermal nuclei also showed staining, ,ß-galactosidase apparently localized to nuclei adjacent to branches of the excretory cell. This plasmid hybridizes to Y55E1 1, Y53F3 , Y50C9 ,and Y73B6 on LGIV. There is an integrated transformant for this pattern.
6)p UL#80 G8of pool 80. Embryonic expression at about 100-200 cells as yet uncharacterised. Staining is nuclear localized in 1-8 cells. This plasmid hybridizes to Y40H4 , Y55E4 and Y44H1 on LGV.
The previously described seam cell pattern of pool 80 has not been observed since the initial screen, but a more thorough search search of this pool for the responsible plasmid is underway.
Hope. WBG vol. 11#4,p.58