Worm Breeder's Gazette 1(1): 16

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.

A Laser Microbeam System for Killing Individual Cells

J. White

A Zeiss universal microscope with Nomarski optics has been modified 
by the addition of a semi-silvered mirror mounted behind the objective.
A dye laser giving 0.25 joule pulses at 450 nm wavelength is set up 
so that the beam is brought into focus in the plane of the object.  A 
spot size of about 1.5  m is produced and this can be used to kill 
individual cells in the nematode with no apparent damage to their 
It has been found that there is very little regulation of the 
nematode.  When one of the precursors that migrate into the ventral 
cord is killed, the adjacent ones go through their normal sequence of 
divisions.  The daughters of the precursor that migrates into the RVG 
behave differently from those in the rest of the cord.  When this 
precursor is killed the next one along will go into the RVG.  We are 
at the moment performing an E/M autopsy on one of these animals to see 
whether the daughter cells from this precursor behave as the original 
one would have done or as those from a normal cord precursor.
When the mesodermal blast cell of the hermaphrodite is killed a 
perfectly normal looking animal is produced which is lacking in all 
the cells which derive from that cell.  It cannot lay eggs however, as 
it has no vulval muscles.  When the gonad primordium is killed in the 
hermaphrodite there is no gonad or vulva produced but the vulval 
muscles migrate to the right place and start twitching even though 
there is nothing there.