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.

Laser Manipulation During Early Embryogenesis of Caenorhabditis elegans

Bernd Junkersdorf and Einhard Schierenberg

Figure 1

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]

Figure 1