Worm Breeder's Gazette 14(4): 35 (October 1, 1996)

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.


Olaf Bossinger, Susan Strome

Department of Biology, Indiana University, Jordan Hall, Bloomington IN 47405

Because of its size and simple structure, the gut of C. elegans appears
to be an excellent object to investigate an important and characteristic
process: the generation of epithelial polarity and its relevance for
gut-specific function. In a first step, antisense RNA generated from
cDNA clones  (kindly provided by Y. Kohara) that appear to encode cell
surface receptors and ion-pumps was injected into wildtype hermaphrodite
and the offsprings were examined for proper embryogenesis and gut

In C. elegans lipovitellins are taken up into the gut primordium during
embryogenesis (Bossinger and Schierenberg, 1992) and into the oocytes
from L4 stage onward. Two genes with a predicted structure similar to
that of the low density lipoprotein (LDL) receptor-related protein (LRP)
of mammals have been identified and might be involved in this process
(Yochem and Greenwald, 1993, yk45f9; McCombie et al., 1992,  yk28g2).
After injection of one antisense RNA (yk45f9), no embryonic defects were
observed but larva development arrested in L1-L2. So far we have no
explanation for this behaviour.

The other antisense experiment (yk28g2) gave different results. Embryos
contained reduced number of cytoplasmic granules but nevertheless were
able to develop normally. With the help of centrifugation and antibody
staining, we are currently investigating whether it is yolk granules
that are missing from oocytes and embryos. In the gut primordium we
observed changes in autofluorescence and birefringency. Also, as time
goes the body cavity of injected worms accumulate large amounts of
amorphous material and production of oocytes ceases down. This may be
the result of a reduction/elimination of lipovitellin receptor at the
oocyte surface.

A polyclonal antibody (kindly provided by J. Bohrmann) against the 16 kD
proteolipid component of the vacuolar H+-ATPase in Drosophila (Meagher
et al., 1990) stains the gut primordium in C. elegans from morphogenesis
phase onwards. 2 to 4h after injection of antisense RNA (yk84g10)
embryos show large vacuoles arising in the gut cells (surrounding
birefringent granules) with the onset of morphogenesis phase.
Differentiation of other tissues  appears normal (as inspected with
Nomarski optics). The next batch of embryos produced arrest as monsters
with vacuoles in the gut and visible signs of other tissue
differentiation. The last batch of embryos generated from the antisensed
gonads show the most severe defects. After fertilization they began to
swell and after a few cell divisions multiple nuclei were present in the
cytoplasm and Brownian molecular movement was seen, suggesting defects
in osmoregulation. Because in other systems this vacuolar H+-ATPase is
part of a communication channel called ductin (Finbow et al., 1995), we
are currently investigating its role in cell communication in C. elegans
using dye-coupling studies.

References: Bossinger and Schierenberg, 1992 Development 114: 317-330;
Finbow et al., 1995 Bioessays 17: 247-255; McCombie et al., 1992 Nature
Genetics 1: 124-131; Meagher et al., 1990 Nuc. Acids Res. 18: 6712-6712;
Yochem and Greenwald, 1993 PNAS 90: 4572-4576.