Worm Breeder's Gazette 10(3): 160
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.
Individual blastomeres in early C. elegans embryos have been ablated using a laser microbeam coupled to a microscope. For this the nucleus of a selected cell is irradiated with several short laser pulses (386 nm). At low doses cells continue cleavage but express considerably prolonged cell cycle rhythms. For early developmental stages higher doses of irradiation are necessary to induce cleavage arrest than in more advanced stages. In the 2-cell stage we have neither been able to ablate AB nor P1 without damaging their sister cell. When the germline cell P2 is irradiated in the 4-cell stage, such that the neighboring cells do not show any visible defects, P2 does at least pass through one more cleavage. Such embryos develop into monsters with several hundred cells, expressing differentation markers like muscle twitching and gut birefringency. After irradiation of P3 (passing through one more division) a hatching worm can develop, lacking muscle cells in the central part of the body ( normally generated by D). Such a worm does not reproduce due to the missing primordial germ cell P4. After ablation of P4 (no further divisions) a sterile worm develops without any defects in somatic tissue. Ablation of the D cell results in a hatching juvenile with more or less uncoordinated movement. During postembryonic development visible defects decrease and often a normal behaving, reproducing adult emerges. The ablation of the precursor for the anterior (Ea) or the posterior half (Ep) of the intestine, results in a hatching juvenile with only half a gut (see sketch below). Nevertheless such animals have developed a functional, normal looking and pumping pharynx. They can survive several days but never reach adulthood. Our results of early cell ablations have not revealed any new cases of intercellular regulation but are in accordance with the concept of mosaic development. [See Figure 1]