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.
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 morphogenesis. 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.