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.
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