Worm Breeder's Gazette 17(1): 41 (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.

Suppressor Screen of egl-38 egg-laying defect to study the vulva to uterus signalling pathway

Vandana Rajakumar, Helen M Chamberlin

MCDB Graduate Program, Department of Molecular Genetics, 941, Biological Sciences Building, The Ohio State University,Columbus, OH 43210

Communication between tissues in an organ system during their development is vital to ensure that they function as a unit. The egg-laying system in Caenorhabditis elegans offers a good model system to study this paradigm. Here the reciprocal interactions from the AC to the vulva and from the vulva to the uterus coordinate development between these tissues. The AC initially induces 3 of 6 multipotential Vulval Precursor Cells (VPCs) to form the vulval cells by the LIN-3-LET-23 mediated signalling pathway. Then the 1 vulval cells reciprocally signal to the uterine cells to induce uv 1 cell formation via LIN-3 again. Some genes important for the AC to vulva signal also mediate the vulva to uterus signal, whereas others function in only one or the other developmental pathway. For example, only the vulval transcription of lin-3 requires EGL-38, a PAX transcription factors while the earlier AC expression is EGL-38- independent (1). Although the AC to vulva signal pathway has been studied in detail, the vulva to uterus pathway is less well characterized.

To identify additional genes in the reciprocal pathway from the vulva to the uterus, we have devised a mutagenesis screen for temperature sensitive supressors using egl-38(n578) animals. These animals are egg-laying defective (2,3). We reasoned that mutations in genes that act as negative regulators of the reciprocal pathway may supress the egg-laying defect. Identification and characterization of these suppressor genes would enable us to better understand at a molecular level, the signalling pathway occuring between tissues during their development to form an organ system.

We have carried out two genetic screens using EMS as a mutagen wherein the mutagenized animals are subjected to different temperatures during their development. To identify mutations in genes that may have essential additional functions one screen incorporates a temperature shift during the egg-laying system development:

1.Screen 1: Mutagenized worms allowed to grow at 15 C throughout their development 18,783 gametes were screened and eight candidate supressors were recovered. Two supress at all temperatures, five are cold sensitive and one supresses at 20 C.

2.Screen 2: Mutagenized worms allowed to grow at 15 C at all stages but exposed t 25 C during vulval development.12,375 gametes were screened, wherein five candidate supressors were isolated.Two have been verified to be strong supressors at 15 C while two more are weaker. One candidate seems to require exposure to both 15 C and 25 C during development to exhibit supressor phenotype.Results from screening another 12,408 gametes are still awaited.

  1. Chang, C., Newman, A.P and Sternberg, P.W. (1999) Current Biology 9: 237-246
  2. Trent.C., Tsung ,N and Horvitz, H.R (1983) Genetics 104 : 619-647

(3) Chamberlin, H.M., Palmer, R.E., Newman, A.P., et al (1997) Development 124:

3919-3928