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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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(a–d) Double immunolabeling of SPB components (fluorescein, green) and of meiotic telomeres with antibod-ies against HA-tagged Ndj1p (rhodamine, red) reveals meiosis-specific telomere distribution patterns in mildly spread diploid wild-type SK1 nuclei. (a) Peripheral rim-like distribution of telomeres during early meiosis (140 min). (b and c) Meiocytes with telomeres accumulated at the SPB (bouquet arrangement). (d) Meiocyte nucleus from a later time point (240 min), which shows an SPB and dispersed telomere signals. (e–h) Mildly spread meiocyte nuclei from an independent FISH experiment with the XY′ repeat probe (see Materials and Methods) reveals telomere patterns similar to the ones obtained by Ndj1p IF. (e) Rim-like telomere distribution. (f and g) Bouquet nuclei with clustered telomere signals. (h) Advanced meiocyte from a later time point displays a scattered telomere distribution. Bar, 5 μm (applies to all details). The inset shows colocalization of Ndj1-HA IF signals (red) and XY′ telo-FISH signals (green) in a wild-type pachytene nucleus. Most of the Ndj1-HA and XY′ signals show significant overlap at chromosome ends (e.g., arrowheads). Ndj1 fluorescence is often seen beyond the telo-FISH signals and/or extends between telomere signals. Fewer IF signals in the Ndj1 channel may relate to loss of some epitopes during the FISH procedure.
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Figure 4: (a–d) Double immunolabeling of SPB components (fluorescein, green) and of meiotic telomeres with antibod-ies against HA-tagged Ndj1p (rhodamine, red) reveals meiosis-specific telomere distribution patterns in mildly spread diploid wild-type SK1 nuclei. (a) Peripheral rim-like distribution of telomeres during early meiosis (140 min). (b and c) Meiocytes with telomeres accumulated at the SPB (bouquet arrangement). (d) Meiocyte nucleus from a later time point (240 min), which shows an SPB and dispersed telomere signals. (e–h) Mildly spread meiocyte nuclei from an independent FISH experiment with the XY′ repeat probe (see Materials and Methods) reveals telomere patterns similar to the ones obtained by Ndj1p IF. (e) Rim-like telomere distribution. (f and g) Bouquet nuclei with clustered telomere signals. (h) Advanced meiocyte from a later time point displays a scattered telomere distribution. Bar, 5 μm (applies to all details). The inset shows colocalization of Ndj1-HA IF signals (red) and XY′ telo-FISH signals (green) in a wild-type pachytene nucleus. Most of the Ndj1-HA and XY′ signals show significant overlap at chromosome ends (e.g., arrowheads). Ndj1 fluorescence is often seen beyond the telo-FISH signals and/or extends between telomere signals. Fewer IF signals in the Ndj1 channel may relate to loss of some epitopes during the FISH procedure.

Mentions: Ndj1p is expressed only during meiosis (Chua and Roeder 1997; Conrad et al. 1997); therefore, the distribution patterns detected with this probe exclusively represent meiotic telomere arrangements. The signal patterns obtained by Ndj1p IF matched the telomere distribution patterns revealed by telo-FISH (Fig. 4). Costaining experiments revealed colocalization of HA-tagged Ndj1p and telomere-FISH signals, with the Ndj1-HA signals often extending beyond the XY′ FISH signals (Fig. 4, inset). This could relate to the abundance of Ndj1p at chromosome ends during meiosis and/or to slight swelling of the epitope-bearing chromatin during the FISH procedure. The lack of IF at some telo-FISH signals may relate to loss of protein during the denaturation and hybridization procedure. In any case, we observed that meiotic telomeres, as marked by FISH as well as with anti–HA-Ndj1p, do adopt a peripheral dispersed arrangement in early meiocytes, which is seen as a rim-like fluorescent signal in mild spreads (Fig. 4, a and e) and at the equatorial focus plane of undisrupted nuclei (not shown). At later time points, telomeres congregate to form a single large signal cluster (bouquet arrangement; Fig. 4f and Fig. g) at the SPB (Fig. 4b and Fig. c). This clustering is resolved as cells enter pachytene with telomere signals, again becoming dispersed (Fig. 4 d) (Trelles-Sticken et al. 1999).


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)

(a–d) Double immunolabeling of SPB components (fluorescein, green) and of meiotic telomeres with antibod-ies against HA-tagged Ndj1p (rhodamine, red) reveals meiosis-specific telomere distribution patterns in mildly spread diploid wild-type SK1 nuclei. (a) Peripheral rim-like distribution of telomeres during early meiosis (140 min). (b and c) Meiocytes with telomeres accumulated at the SPB (bouquet arrangement). (d) Meiocyte nucleus from a later time point (240 min), which shows an SPB and dispersed telomere signals. (e–h) Mildly spread meiocyte nuclei from an independent FISH experiment with the XY′ repeat probe (see Materials and Methods) reveals telomere patterns similar to the ones obtained by Ndj1p IF. (e) Rim-like telomere distribution. (f and g) Bouquet nuclei with clustered telomere signals. (h) Advanced meiocyte from a later time point displays a scattered telomere distribution. Bar, 5 μm (applies to all details). The inset shows colocalization of Ndj1-HA IF signals (red) and XY′ telo-FISH signals (green) in a wild-type pachytene nucleus. Most of the Ndj1-HA and XY′ signals show significant overlap at chromosome ends (e.g., arrowheads). Ndj1 fluorescence is often seen beyond the telo-FISH signals and/or extends between telomere signals. Fewer IF signals in the Ndj1 channel may relate to loss of some epitopes during the FISH procedure.
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Related In: Results  -  Collection

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Figure 4: (a–d) Double immunolabeling of SPB components (fluorescein, green) and of meiotic telomeres with antibod-ies against HA-tagged Ndj1p (rhodamine, red) reveals meiosis-specific telomere distribution patterns in mildly spread diploid wild-type SK1 nuclei. (a) Peripheral rim-like distribution of telomeres during early meiosis (140 min). (b and c) Meiocytes with telomeres accumulated at the SPB (bouquet arrangement). (d) Meiocyte nucleus from a later time point (240 min), which shows an SPB and dispersed telomere signals. (e–h) Mildly spread meiocyte nuclei from an independent FISH experiment with the XY′ repeat probe (see Materials and Methods) reveals telomere patterns similar to the ones obtained by Ndj1p IF. (e) Rim-like telomere distribution. (f and g) Bouquet nuclei with clustered telomere signals. (h) Advanced meiocyte from a later time point displays a scattered telomere distribution. Bar, 5 μm (applies to all details). The inset shows colocalization of Ndj1-HA IF signals (red) and XY′ telo-FISH signals (green) in a wild-type pachytene nucleus. Most of the Ndj1-HA and XY′ signals show significant overlap at chromosome ends (e.g., arrowheads). Ndj1 fluorescence is often seen beyond the telo-FISH signals and/or extends between telomere signals. Fewer IF signals in the Ndj1 channel may relate to loss of some epitopes during the FISH procedure.
Mentions: Ndj1p is expressed only during meiosis (Chua and Roeder 1997; Conrad et al. 1997); therefore, the distribution patterns detected with this probe exclusively represent meiotic telomere arrangements. The signal patterns obtained by Ndj1p IF matched the telomere distribution patterns revealed by telo-FISH (Fig. 4). Costaining experiments revealed colocalization of HA-tagged Ndj1p and telomere-FISH signals, with the Ndj1-HA signals often extending beyond the XY′ FISH signals (Fig. 4, inset). This could relate to the abundance of Ndj1p at chromosome ends during meiosis and/or to slight swelling of the epitope-bearing chromatin during the FISH procedure. The lack of IF at some telo-FISH signals may relate to loss of protein during the denaturation and hybridization procedure. In any case, we observed that meiotic telomeres, as marked by FISH as well as with anti–HA-Ndj1p, do adopt a peripheral dispersed arrangement in early meiocytes, which is seen as a rim-like fluorescent signal in mild spreads (Fig. 4, a and e) and at the equatorial focus plane of undisrupted nuclei (not shown). At later time points, telomeres congregate to form a single large signal cluster (bouquet arrangement; Fig. 4f and Fig. g) at the SPB (Fig. 4b and Fig. c). This clustering is resolved as cells enter pachytene with telomere signals, again becoming dispersed (Fig. 4 d) (Trelles-Sticken et al. 1999).

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