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The nucleolus of Caenorhabditis elegans.

Lee LW, Lee CC, Huang CR, Lo SJ - J. Biomed. Biotechnol. (2012)

Bottom Line: Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli.This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control.Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, College of Medicine, Chang Gung University, TaoYuan 333, Taiwan.

ABSTRACT
Nucleolar size and appearance correlate with ribosome biogenesis and cellular activity. The mechanisms underlying changes in nucleolar appearance and regulation of nucleolar size that occur during differentiation and cell cycle progression are not well understood. Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli. This paper details the advantages of using C. elegans to investigate features of the nucleolus during the organism's development by following dynamic changes in fibrillarin (FIB-1) in the cells of early embryos and aged worms. This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control. Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy.

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Comparison of the nucleolar size in ncl-1 and N2 worms. (a) N2 and ncl-1 background transgenic worms (as indicated) side by side and photographed under a fluorescence microscope to show the head region. The heads of both worms are facing left. Double arrowheads indicate nucleoli where the nucleolar protein (FIB-1::GFP) expression was less affected by NCL-1 than nucleoli marked by a single arrow. (b) Schematic illustration of ventral cord neurons and hypodermal cell lineages (upper panel). The fluorescence micrograph shows that the hypodermis nucleolar size (indicated by double arrowheads) is larger than nucleoli in neuronal cells (indicated by single arrowheads). The worm head is facing left and the ventral side is at the top. (c) A worm gonad arm-section treated with RNAi against the ncl-1 gene shows a similar appearance to the -1 oocyte nucleolus (arrowhead) of ncl-1 mutants. Scale bars indicate 20 μm.
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fig3: Comparison of the nucleolar size in ncl-1 and N2 worms. (a) N2 and ncl-1 background transgenic worms (as indicated) side by side and photographed under a fluorescence microscope to show the head region. The heads of both worms are facing left. Double arrowheads indicate nucleoli where the nucleolar protein (FIB-1::GFP) expression was less affected by NCL-1 than nucleoli marked by a single arrow. (b) Schematic illustration of ventral cord neurons and hypodermal cell lineages (upper panel). The fluorescence micrograph shows that the hypodermis nucleolar size (indicated by double arrowheads) is larger than nucleoli in neuronal cells (indicated by single arrowheads). The worm head is facing left and the ventral side is at the top. (c) A worm gonad arm-section treated with RNAi against the ncl-1 gene shows a similar appearance to the -1 oocyte nucleolus (arrowhead) of ncl-1 mutants. Scale bars indicate 20 μm.

Mentions: Transgenic worms expressing FIB-1::GFP in wild-type (N2) and ncl-1 background worms are easily distinguishable because in the former, nucleoli appear as weak GFP foci and are few in number, while the latter have more foci and produce a stronger GFP signal (Figure 3(a)). Absence of NCL-1 causes an increase in FIB-1 expression and an enlargement of nucleoli in the cell; however, the magnitudes of these effects are not the same for each cell (compare the cells indicated by a double arrowhead and single arrowheads in Figure 3(a)). There may be different levels of ncl-1 expression in various tissues, for example, the precursor cells of the intestine are the first cell type to lose NCL-1 during embryogenesis [28]. Another interesting feature is the difference in nucleolar size seen in the hypodermis, adjacent to five ventral neurons in worm larva (Figure 3(b), lower panel). The five ventral cord neurons share the same hypodermis precursor cell (Figure 3(b), upper panel). It would be interesting to know whether the hypodermis displays a decrease of NCL-1, or if the ventral neuron expresses greater levels of NCL-1 immediately after precursor cells have completed asymmetric cell division. A recent study on the ASE gustatory neurons revealed that asymmetric ASE cell size, in which the ASER soma is larger than that of ASEL, is under developmental control [39]. ASER and ASEL neuron nucleoli size and number are also different. These are affected by the fib-1 gene, and directly or indirectly are regulated by die-1, which encodes a Zn finger transcription factor [39]. These findings support the hypothesis that asymmetric cell division during development, may alter expression of regulator factors that control nucleolar size.


The nucleolus of Caenorhabditis elegans.

Lee LW, Lee CC, Huang CR, Lo SJ - J. Biomed. Biotechnol. (2012)

Comparison of the nucleolar size in ncl-1 and N2 worms. (a) N2 and ncl-1 background transgenic worms (as indicated) side by side and photographed under a fluorescence microscope to show the head region. The heads of both worms are facing left. Double arrowheads indicate nucleoli where the nucleolar protein (FIB-1::GFP) expression was less affected by NCL-1 than nucleoli marked by a single arrow. (b) Schematic illustration of ventral cord neurons and hypodermal cell lineages (upper panel). The fluorescence micrograph shows that the hypodermis nucleolar size (indicated by double arrowheads) is larger than nucleoli in neuronal cells (indicated by single arrowheads). The worm head is facing left and the ventral side is at the top. (c) A worm gonad arm-section treated with RNAi against the ncl-1 gene shows a similar appearance to the -1 oocyte nucleolus (arrowhead) of ncl-1 mutants. Scale bars indicate 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3345250&req=5

fig3: Comparison of the nucleolar size in ncl-1 and N2 worms. (a) N2 and ncl-1 background transgenic worms (as indicated) side by side and photographed under a fluorescence microscope to show the head region. The heads of both worms are facing left. Double arrowheads indicate nucleoli where the nucleolar protein (FIB-1::GFP) expression was less affected by NCL-1 than nucleoli marked by a single arrow. (b) Schematic illustration of ventral cord neurons and hypodermal cell lineages (upper panel). The fluorescence micrograph shows that the hypodermis nucleolar size (indicated by double arrowheads) is larger than nucleoli in neuronal cells (indicated by single arrowheads). The worm head is facing left and the ventral side is at the top. (c) A worm gonad arm-section treated with RNAi against the ncl-1 gene shows a similar appearance to the -1 oocyte nucleolus (arrowhead) of ncl-1 mutants. Scale bars indicate 20 μm.
Mentions: Transgenic worms expressing FIB-1::GFP in wild-type (N2) and ncl-1 background worms are easily distinguishable because in the former, nucleoli appear as weak GFP foci and are few in number, while the latter have more foci and produce a stronger GFP signal (Figure 3(a)). Absence of NCL-1 causes an increase in FIB-1 expression and an enlargement of nucleoli in the cell; however, the magnitudes of these effects are not the same for each cell (compare the cells indicated by a double arrowhead and single arrowheads in Figure 3(a)). There may be different levels of ncl-1 expression in various tissues, for example, the precursor cells of the intestine are the first cell type to lose NCL-1 during embryogenesis [28]. Another interesting feature is the difference in nucleolar size seen in the hypodermis, adjacent to five ventral neurons in worm larva (Figure 3(b), lower panel). The five ventral cord neurons share the same hypodermis precursor cell (Figure 3(b), upper panel). It would be interesting to know whether the hypodermis displays a decrease of NCL-1, or if the ventral neuron expresses greater levels of NCL-1 immediately after precursor cells have completed asymmetric cell division. A recent study on the ASE gustatory neurons revealed that asymmetric ASE cell size, in which the ASER soma is larger than that of ASEL, is under developmental control [39]. ASER and ASEL neuron nucleoli size and number are also different. These are affected by the fib-1 gene, and directly or indirectly are regulated by die-1, which encodes a Zn finger transcription factor [39]. These findings support the hypothesis that asymmetric cell division during development, may alter expression of regulator factors that control nucleolar size.

Bottom Line: Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli.This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control.Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences, College of Medicine, Chang Gung University, TaoYuan 333, Taiwan.

ABSTRACT
Nucleolar size and appearance correlate with ribosome biogenesis and cellular activity. The mechanisms underlying changes in nucleolar appearance and regulation of nucleolar size that occur during differentiation and cell cycle progression are not well understood. Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli. This paper details the advantages of using C. elegans to investigate features of the nucleolus during the organism's development by following dynamic changes in fibrillarin (FIB-1) in the cells of early embryos and aged worms. This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control. Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy.

Show MeSH
Related in: MedlinePlus