Worm Breeder's Gazette 10(3): 159

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.

Microinjection of Lucifer Yellow into Early Blastomeres of C. elegans

Olaf Bossinger and Einhard Schierenberg

Intercellular communication via gap junctions during development has 
been described for various organisms.  Molecules below 1500 daltons 
can pass through gap junctions from one cell to another.  The 
fluorescent dye LUCIFER YELLOW (LY) can be used as a visible indicator 
for this type of cell-cell interaction.  
We have microinjected droplets of LY (6% in aqua bidest.) into 
various early blastomeres of the C.  elegans embryo.  One- or two-cell 
stages were fixed to polylysine-coated coverslips and covered with a 
drop of extrusion medium (Laufer et al.,1980, Cell 19, 569).  To 
prevent evaporation during manipulation the preparations were sealed 
with oxygen-penetrable silicon oil.  For microinjection we use a Leitz 
micromanipulator and an old Zeiss inverted microscope with Nomarski 
optics (100X objective).  With oil pressure LY is injected through an 
extended borosilicate capillary with inner filament (theta < 0.1  m) 
into the nucleus of the selected cell.  The injected droplet does not 
interfere with normal development.  During cleavage it is frequently 
segregated into the nucleus of one daughter cell.  At the desired 
stage the droplet can be dissolved under microscopical control by 
short irradiation with light of 520-560 nm wavelength.  
Fluorescence distributes quickly and in a diffused fashion through 
all cells of the embryo.  After a while, however, small fluorescent 
granules form.  During the continuing proliferation an apparent 
transfer of fluorescence towards the gut precursors (E cells) takes 
place.  During the later morphogenesis phase this process terminates.  
At that time fluorescence is exclusively found in the cytoplasm of the 
gut cells.  The stepwise increasing intensity of fluorescence in the E 
cells suggests that a transfer of LY into the intestinal primordium 
takes place (starting long before the visible differentiation of gut 
cells) rather than a degradation of fluorescence in the other cells.  
Embryos  injected in the way indicated above, can develop normally, 
hatch, and reproduce.  No LY- induced fluorescence was found in the 
progeny of such worms.  
The observed distribution of LY may reflect a coupling in the embryo 
which is unspecific in the beginning but becomes specific later on.  
A very similar distribution of fluorescence has been in the C.  
elegans embryo by W.  Sharrock (1983, Dev Biol.  96, 182) after 
marking yolk protein with antibody.   It remains to be tested whether 
a functional correlation exists between these two observations