Worm Breeder's Gazette 10(2): 82
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.
lin-12(0) hermaphrodites are essentially sterile. As reported in the last edition of the Gazette, Tim Schedl first recognized that, in lin-12(0) hermaphrodites, the proximal germ cells do not enter meiosis but seem to continue to proliferate in the mitotic cycle, like the distal germ cells (see Figure), although gametes are present in the loop region. We were interested in ascertaining whether lin-12 is required in the somatic gonad or in the germ line for proper germ line development. Mosaic hermaphrodites obtained from the strain qDp3: 65) 51) 41) were useful in distinguishing between these two possibilities. [qDp3 ( Austin and Kimble, 1987) complements ncl-1, 41) is a null allele of lin- 12.] Five mosaics were obtained in which half of the gonad ( either the Z1 or the Z4 descendants) was Ncl- and therefore presumably lin-12( 0). The presence of the Dp in the germ line was ascertained by looking for WT animals among the progeny of the mosaic hermaphrodite. In 5/5 mosaics, the half of the gonad not expressing lin-12 exhibited the lin-12(0) defect in the germ line, while the other wild-type half contained a normally differentiated germ line (see Figure); all mosaics produced some wild-type progeny. These results are consistent with lin-12 function being required in the somatic gonad for wild-type development of the germ line. (Our previous tentative inference of a requirement for lin-12(+) in the germ line was based on a mosaic phenotypic class that is also consistent with the interpretation presented here.) One possibility is that lin-12(0) animals have another, as yet unidentified, cell fate transformation in the gonad. This transformation would create a cell in the proximal part of the gonad that can promote mitosis in the germ line, a role normally associated only with the distal tip cell. Another possibility is that lin-12 plays a more direct role in germ line development. We hope to distinguish between these possibilities by laser ablation experiments.