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Meiotic telomere protein Ndj1p is required for meiosis-specific telomere distribution, bouquet formation and efficient homologue pairing.

Trelles-Sticken E, Dresser ME, Scherthan H - J. Cell Biol. (2000)

Bottom Line: Since ndj1Delta meiocytes fail to cluster their telomeres at any prophase stage, Ndj1p is the first protein shown to be required for bouquet formation in a synaptic organism.Analysis of homologue pairing by two-color fluorescence in situ hybridization with cosmid probes to regions on III, IX, and XI revealed that disruption of bouquet formation is associated with a significant delay (>2 h) of homologue pairing.Under naturally occurring conditions, bouquet formation may allow for rapid sporulation and confer a selective advantage.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Biology and Genetics, University of Kaiserslautern, D-67653 Kaiserslautern, Germany.

ABSTRACT
We have investigated the requirements for NDJ1 in meiotic telomere redistribution and clustering in synchronized cultures of Saccharomyces cerevisiae. On induction of wild-type meiosis, telomeres disperse from premeiotic aggregates over the nuclear periphery, and then cluster near the spindle pole body (bouquet arrangement) before dispersing again. In ndj1Delta meiocytes, telomeres are scattered throughout the nucleus and fail to form perinuclear meiosis-specific distribution patterns, suggesting that Ndj1p may function to tether meiotic telomeres to the nuclear periphery. Since ndj1Delta meiocytes fail to cluster their telomeres at any prophase stage, Ndj1p is the first protein shown to be required for bouquet formation in a synaptic organism. Analysis of homologue pairing by two-color fluorescence in situ hybridization with cosmid probes to regions on III, IX, and XI revealed that disruption of bouquet formation is associated with a significant delay (>2 h) of homologue pairing. An increased and persistent fraction of ndj1Delta meiocytes with Zip1p polycomplexes suggests that chromosome polarization is important for synapsis progression. Thus, our observations support the hypothesis that meiotic telomere clustering contributes to efficient homologue alignment and synaptic pairing. Under naturally occurring conditions, bouquet formation may allow for rapid sporulation and confer a selective advantage.

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Confocal light optical sections at the equatorial planes of (a) a wild-type (taken at 240 min) and (b) an ndj1Δ nucleus (taken at 470 min) showing telomere-associated Rap1 signals (FITC, yellow) and DNA fluorescence (DAPI, blue). In the wild-type nucleus (a), telomeric Rap1p signals are confined to the nuclear periphery. The ndj1Δ meiocyte nuclear section (b) shows telomeric Rap1p signals at the periphery and within the nuclear interior. Bar, 2 μm.
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Figure 6: Confocal light optical sections at the equatorial planes of (a) a wild-type (taken at 240 min) and (b) an ndj1Δ nucleus (taken at 470 min) showing telomere-associated Rap1 signals (FITC, yellow) and DNA fluorescence (DAPI, blue). In the wild-type nucleus (a), telomeric Rap1p signals are confined to the nuclear periphery. The ndj1Δ meiocyte nuclear section (b) shows telomeric Rap1p signals at the periphery and within the nuclear interior. Bar, 2 μm.

Mentions: To test whether the ndj1Δ mutation affects the meiosis-specific three-dimensional telomere distribution (i.e., peripheral location of dispersed telomeres in the meiocyte nucleus), we performed Rap1p staining with undisrupted nuclei and investigated the three-dimensional spot distribution by laser scanning microscopy and digital image analysis. Telomeric Rap1p signal spots and the corresponding DAPI-stained nuclei were obtained by light optical serial sectioning (Fig. 6). Because nuclei in meiotic prophase are nonspherical and nuclear pore staining failed to reveal the typical rim staining seen in mitotic interphase (not shown), we determined the nuclear boundary in light optical sections of DAPI-stained nuclei. DAPI highly selectively stains DNA and renders the nuclear boundary at a high contrast. The number and relation of Rap1p signal centers to the nearest sector of the nuclear boundary was computed from 30 nuclei of uninucleate cells, 10 each at 4, 7, and 12 h after induction of meiosis from wild type and ndj1Δ. Bouquet nuclei, which rarely exceed 5–10% at any time point in this strain background, were excluded from this analysis (see Materials and Methods). The 30 prophase nuclei from wild-type and ndj1Δ cells were analyzed as a single class, where totals of 519 and of 729 Rap1p spots were scored, respectively. The difference in the number of total spots is consistent with the smaller number of larger Rap1p signals seen in spread meiotic prophase nuclei of wild type, compared with ndj1Δ cells (Conrad et al. 1997).


Meiotic telomere protein Ndj1p is required for meiosis-specific telomere distribution, bouquet formation and efficient homologue pairing.

Trelles-Sticken E, Dresser ME, Scherthan H - J. Cell Biol. (2000)

Confocal light optical sections at the equatorial planes of (a) a wild-type (taken at 240 min) and (b) an ndj1Δ nucleus (taken at 470 min) showing telomere-associated Rap1 signals (FITC, yellow) and DNA fluorescence (DAPI, blue). In the wild-type nucleus (a), telomeric Rap1p signals are confined to the nuclear periphery. The ndj1Δ meiocyte nuclear section (b) shows telomeric Rap1p signals at the periphery and within the nuclear interior. Bar, 2 μm.
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Related In: Results  -  Collection

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Figure 6: Confocal light optical sections at the equatorial planes of (a) a wild-type (taken at 240 min) and (b) an ndj1Δ nucleus (taken at 470 min) showing telomere-associated Rap1 signals (FITC, yellow) and DNA fluorescence (DAPI, blue). In the wild-type nucleus (a), telomeric Rap1p signals are confined to the nuclear periphery. The ndj1Δ meiocyte nuclear section (b) shows telomeric Rap1p signals at the periphery and within the nuclear interior. Bar, 2 μm.
Mentions: To test whether the ndj1Δ mutation affects the meiosis-specific three-dimensional telomere distribution (i.e., peripheral location of dispersed telomeres in the meiocyte nucleus), we performed Rap1p staining with undisrupted nuclei and investigated the three-dimensional spot distribution by laser scanning microscopy and digital image analysis. Telomeric Rap1p signal spots and the corresponding DAPI-stained nuclei were obtained by light optical serial sectioning (Fig. 6). Because nuclei in meiotic prophase are nonspherical and nuclear pore staining failed to reveal the typical rim staining seen in mitotic interphase (not shown), we determined the nuclear boundary in light optical sections of DAPI-stained nuclei. DAPI highly selectively stains DNA and renders the nuclear boundary at a high contrast. The number and relation of Rap1p signal centers to the nearest sector of the nuclear boundary was computed from 30 nuclei of uninucleate cells, 10 each at 4, 7, and 12 h after induction of meiosis from wild type and ndj1Δ. Bouquet nuclei, which rarely exceed 5–10% at any time point in this strain background, were excluded from this analysis (see Materials and Methods). The 30 prophase nuclei from wild-type and ndj1Δ cells were analyzed as a single class, where totals of 519 and of 729 Rap1p spots were scored, respectively. The difference in the number of total spots is consistent with the smaller number of larger Rap1p signals seen in spread meiotic prophase nuclei of wild type, compared with ndj1Δ cells (Conrad et al. 1997).

Bottom Line: Since ndj1Delta meiocytes fail to cluster their telomeres at any prophase stage, Ndj1p is the first protein shown to be required for bouquet formation in a synaptic organism.Analysis of homologue pairing by two-color fluorescence in situ hybridization with cosmid probes to regions on III, IX, and XI revealed that disruption of bouquet formation is associated with a significant delay (>2 h) of homologue pairing.Under naturally occurring conditions, bouquet formation may allow for rapid sporulation and confer a selective advantage.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Biology and Genetics, University of Kaiserslautern, D-67653 Kaiserslautern, Germany.

ABSTRACT
We have investigated the requirements for NDJ1 in meiotic telomere redistribution and clustering in synchronized cultures of Saccharomyces cerevisiae. On induction of wild-type meiosis, telomeres disperse from premeiotic aggregates over the nuclear periphery, and then cluster near the spindle pole body (bouquet arrangement) before dispersing again. In ndj1Delta meiocytes, telomeres are scattered throughout the nucleus and fail to form perinuclear meiosis-specific distribution patterns, suggesting that Ndj1p may function to tether meiotic telomeres to the nuclear periphery. Since ndj1Delta meiocytes fail to cluster their telomeres at any prophase stage, Ndj1p is the first protein shown to be required for bouquet formation in a synaptic organism. Analysis of homologue pairing by two-color fluorescence in situ hybridization with cosmid probes to regions on III, IX, and XI revealed that disruption of bouquet formation is associated with a significant delay (>2 h) of homologue pairing. An increased and persistent fraction of ndj1Delta meiocytes with Zip1p polycomplexes suggests that chromosome polarization is important for synapsis progression. Thus, our observations support the hypothesis that meiotic telomere clustering contributes to efficient homologue alignment and synaptic pairing. Under naturally occurring conditions, bouquet formation may allow for rapid sporulation and confer a selective advantage.

Show MeSH
Related in: MedlinePlus