Worm Breeder's Gazette 13(4): 52 (October 1, 1994)

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.

Tissue Distribution of the EMB-5 Protein During Development.

Kiyoji Nishiwaki, Tohru Sano, Yo Tabuse, Johji Miwa

Fundamental Research Laboratories, NEC Corporation, Miyukigaoka, Tsukuba 305, Japan

  The emb-5 gene is required for the correct timing of gut precursor cell division
during gastrulation(1, 2) and for the proliferation of germ cells during postembryonic
development(3). emb-5 encodes the protein EMB-5 homologous to the yeast nuclear
protein SPT6 ,which has been shown to affect the transcription of a variety of genes and
suggested to play a role in chromatin assembly or modification(4). To understand the
tissue distribution pattern of EMB-5 during development, we have conducted the
epitope-tagging analysis using the antigenic epitope of hemagglutinin of influenza
virus (HA1). The emb-5 gene epitope-tagged at the 5'-end was active and rescued the
emb-5 mutant phenotype although more weakly than did the wild type gene. Using a
strain with chromosomally integrated DNA(epitope tagged emb-5 + rol-6 [d]),we found
that the anti-epitope antibodies stained interphase nuclei of various cell types,
although they did not stain early embryonic cells before the 51-cell stage and germ cells
in all stages including mature oocytes and sperm (We used the polyclonal HA.11
antibody from BAbCO because the monoclonal antibody 12 CA5 from Boehringer gave
substantial background staining of worm nuclei ) On the other hand, the antibodies
against an EMB-5 C-terminal peptide stained all the interphase nuclei except for the
germ cell nuclei before the adult stage in the same strain, although the mature sperm
were not stained as in the case of the anti-epitope antibodies In embryos, the germline
precursor cells P[0] to P[3] appeared to be stained but not the germline cells P[4], Z2
,and Z3 These results suggest that EMB-5 may have modifications on its N-terminus
in early embryonic cells and adult germ cells, and that it may have modifications on
both of its N- and C-termini or not be present in germ cells before the adult stage and
mature sperm It is possible that EMB-5 is not required for the mature sperm lacking
chromatin proteins It is interesting that the early embryonic cells and germ cells,
where the temperature-sensitive emb-5 mutations show remarkable effects, seem to
have modified EMB-5 proteins However, because we are analyzing the artificially
introduced epitope-tagged gene, we have to be careful in interpreting its expression
pattern. We are currently preparing antibodies against an N-terminal peptide and
several internal peptides of EMB-5
 (1) Miwa et al. (1980) Dev Biol 76, 160- 174
 (2) Schierenberg et al.(1980) Dev Biol 76, 141-159
 (3) Nishiwaki, Miwa, and Hedgecock, unpublished
 (4) Nishiwaki et al. (1993) Mol Gen Genet 239, 313-322