Worm Breeder's Gazette 11(4): 114

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.

The Pattern of Dye-Coupling in Embryos of Different Free-Living Nematodes

Olaf Bossinger and Einhard Schierenberg

As described in WBG 10(3), we have microinjected Lucifer Yellow(LY) 
into the embryo of C.  elegans as a marker for dye coupling.  
Meanwhile we have extended our studies to other free-living nematodes. 
In C.  elegans LY quickly distributes all over the early embryo.  If 
fluorescently labeled Dextrane is injected, it always remains in the 
marked cell and its progeny, indicating that the observed dye-coupling 
is not due to cytoplasmic bridges.  Only after the formation of P4 (
primordial germ cell), this cell and its sister temporarily form a dye-
coupling compartment by their own.  But just P4 and its daughters Z2 
and Z3 remain permanently discoupled while D joins again the one large 
dye-coupling compartment comprising all somatic cells.  If LY is 
injected into P4 it remains restricted to this cell and its 
descendants.  In two other species Rhabditis dolichura and Cephalobus 
spec.  which develop considerably slower, we found in the early embryo 
similar pattern of dye-coupling as in C.  elegans.  However, here 
passage of the injected tracer appears to take place only luring a 
distinct phase of the cell cycle, i.e.  during interphase.  
In C.  elegans the phase of complete coupling of somatic cells 
extends into late proliferation.  Although we have some problems with 
injecting into small blastomeres, preliminary data indicate that 
during early morphogenesis tissue-specific compartments form.  
In Cephalobus this restriction in dye-coupling leading to the 
establishment of several distinct communication compartments appears 
to occur considerably earlier.  Presently we test the idea that the 
pattern of dye-coupling is more correlated to absolute time of 
development rather than to the cell stage reached.  This assumption is 
supported by our finding that in slower developing nematodes we have 
studied the typical autofluorescence appears visibly earlier in the 
gut lineage than in C.  elegans.