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Expr2579
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SCC-1/COH-2 was expressed in germ cells throughout the development, including the adult stage. SCC-1/COH-2 was detected in virtually all mitotic germ nuclei. Similarly to somatic cells in embryos, SCC-1/COH-2 was dispersed in the cytoplasm at mitotic prometaphase and was absent from the condensed anaphase chromosomes in germ cells. In female germ cells that entered meiotic prophase in adult hermaphrodites, SCC-1/COH-2 was observed uniformly in the nuclei. It was unclear whether SCC-1/COH-2 localized to the condensed meiotic chromosomes, because of the strong SCC-1/COH-2 signal emitted from the nucleoplasm. SCC-1/COH-2 was detected also in male germ cells at mitosis and meiosis, but it was not detectable in mature sperm. SCC-1/COH-2 was strongly expressed in virtually all cells in early embryos, but its expression was gradually weakened, and the signal could hardly be detected in late embryos, in which cell division was ceased almost completely. Strong nuclear signals of SCC-1/COH-2 reappeared in larvae, though they were limited to a subset of cells. SCC-1/COH-2 was detectable only in cells that were going to divide. For example, in an L1 larva, intense SCC-1/COH-2 signals were detected in the 14 hypodermal V lineage cells, which divide synchronously. The SCC-1/COH-2 signal was dispersed and not detectable on condensed chromosomes, as observed in embryos of an intermediate stage. In a slightly older L1 larva, expression of SCC-1/COH-2 was seen in 22 P lineage cells to constitute the ventral nerve cord and in four Q lineage cells to produce posterior neuronal cells, all of which divide at the same time. In this L1 larva, no signal was detected in the V lineage cells, suggesting that the SCC-1/COH-2 protein is present only for a short time in the cell cycle, and likely to be degraded quickly after cell division. Larvae of later stages also expressed SCC-1/COH-2 in dividing cells: in an L3 larva, SCC-1/COH-2 was detected in four M lineage cells to produce the uterine and vulval muscle cells and in 10 P lineage vulval precursor cells, which divide concurrently. The embryos were stained with both anti-SCC-1/COH-2 antibodies and an antibody against a component of the nuclear pore complexes. The SCC-1/COH-2 signal was evenly distributed within the nuclear envelope except for the chromosomal region, suggesting that SCC-1/COH-2 molecules dissociated from the chromosomes at metaphase were trapped by the nuclear envelope. Consistently with this interpretation, the SCC-1/COH-2 staining around the metaphase plate was no longer seen at later stages of embryogenesis involving >30 cells, where nuclear envelope is known to break down before metaphase. SCC-1/COH-2 was dispersed into the whole cytoplasm of metaphase cells at these stages. |
SCC-1/COH-2 seemed to localize to the chromosomes in a cell cycle-dependent manner. In interphase, SCC-1/COH-2 was seen throughout the nucleus, overlapping largely with DNA. At mitotic prophase, SCC-1/COH-2 started to separate from condensing chromosomes, and it was not detected on the chromosomes at prometaphase and metaphase. At metaphase, the SCC-1/COH-2 signal seemed as if surrounding the metaphase plate, although it was possible that a small amount of SCC-1/COH-2 was remaining on the metaphase chromosomes but escaped detection, because cohesin is reported to become detectable on metaphase chromosomes only after detergent extraction of soluble background in other metazoans. The SCC-1/COH-2 signal was then dispersed in the cytoplasm at anaphase. At telophase, the SCC-1/COH-2 protein began to reaccumulate on the chromosomes. |
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Expr9973
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Expression of gfp::sem-2 was first detectable in a subset of cells of the E and MS lineages in early gastrulating-stage embryos. The gfp::sem-2 expression persisted through embryonic and larval development in many cell types, including vulval, hypodermal and intestinal cells. gfp::sem-2 expression in the M lineage was first detectable at the 16-M stage in the SM mother cells, M.v(l/r)pa, and remained in both of their daughter cells, M.v(l/r)paa and M.v(l/r)pap. The presence of GFP::SEM-2 in M.v(l/r)pap was transient: GFP::SEM-2 was not detectable after M.v(l/r)pap differentiated into BWMs. However, GFP::SEM-2 persisted in the nuclei of the SM cells and all their descendants until the 8-SM stage, and became undetectable at the 16-SM stage. |
The GFP::SEM-2 protein was nuclear localized, consistent with its predicted role as a transcription factor. |
