Acta Biologica 38. (1987)
2. szám - J. Szabad–M. Erdélyi–J. Szidonya: Characterization of Fs(2)1, a germ-line dependent dominant female sterile mutation of Drosophila
J. SZABAD et al. However, if the mosaic egg primordium exhibits normal development, the mutation is generally considered to be somatic (follicular) dependent. Mosaic egg primordia are generated either by the transplantation of pole cells (ancestors of germ-line cells, /8/ or by the dominant female sterile technique, /9/). The dominant female sterile technique makes use of germ-line dependent dominant female sterile mutations (Fs). Mitotic recombination is induced in oogonial cells heterozygous for Fs and the m mutation to be studied. (The mutations Fs and m are located in trans on the same arm of the homologous chromosomes.) The Fs-free daughter cell may continue development (unless the m mutation interferes with it) and give rise to mosaic egg primordia in which the m homozygous germ-line cells are surrounded by m heterozygous follicular cells. (Although the follicular cells are Fs heterozygous, they develop normally because Fs does not disturb the functions of these cells.) Two Fs mutations have been reported and used in the dominant female sterile technique: Fs(2)D /10, 12/ and Fs(l)K1237 /2, 4/ for a review see /5/. Fs(l)K1237 is X-linked, while Fs(2)D is located on distal 2R. We have recently carried out a systematic screen for the isolation of EMS-induced autosomal Fs mutations. From over 70 Fs mutations induced only one — Fs(2)l — emerged that can be used for the construction of germline mosaics /3/. This paper describes the characteristics of Fs(2)l. MATERIALS AND METHODS The analysis of Fs(2)l/al dp b prcc ppL s£ females is described. They were derived from a cross between ai cp b рг c px sp homozygous females and Fs(2)l/Cy Roi or Fs(2)l/Bc Gla males, al, dp, b, pr, c, px and sp are recessive, while Cy, Roi~Be and Gla are dominant marker mutations located on balancer chromosomes. /For a description see 6./ The Fs(2)l males were derived from a stock in which Be Gla/Су Roi females were mated with Fs(2)l/Bc Gla or Fs(2)l/Cy Roi males, and the fertile Be Gla/Су Roi males were discarded in every generation. For the study of egg morphology, eggs deposited by the Fs(2)l heterozygous females were fixed in an acetic acid: glycerol (1:1) mixture at 60 UC for one hour, mounted in Hoyer's medium and cleared for 1-2 days at 60 и /11/. Ovaries were analyzed on Feulgen-stained whole mounts. For the induction of germ-line mosaicism, late second to early third instar larvae (46-50 h after oviposition) or 3-5-day-old adult females were irradiated with 1500 R of X-rays (150 kV, 0.5 mm Al filter, 1000 R/min). In the case of adult irradiations, females were mated with al dp b pr c px sp homozygous males prior to X-raying. Lots of five females plus 8-10 males were transferred into vials and screened for mosaicism throughout 10-14 days. This period is necessary to identify over 95% of the mosaics /10/. Upon the detection of mosaicism, females were screened individually for several more days.