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The dissection of meiotic chromosome movement in mice using an in vivo electroporation technique.

Shibuya H, Morimoto A, Watanabe Y - PLoS Genet. (2014)

Bottom Line: Further, during bouquet stage, telomeres are constrained near the MTOC, resulting in the transient suppression of telomere mobility and nuclear rotation.In contrast, actin regulates the oscillatory changes in nuclear shape.Our data provide the mechanical scheme for meiotic chromosome movement throughout prophase I in mammals.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo, Japan.

ABSTRACT
During meiosis, the rapid movement of telomeres along the nuclear envelope (NE) facilitates pairing/synapsis of homologous chromosomes. In mammals, the mechanical properties of chromosome movement and the cytoskeletal structures responsible for it remain poorly understood. Here, applying an in vivo electroporation (EP) technique in live mouse testis, we achieved the quick visualization of telomere, chromosome axis and microtubule organizing center (MTOC) movements. For the first time, we defined prophase sub-stages of live spermatocytes morphologically according to GFP-TRF1 and GFP-SCP3 signals. We show that rapid telomere movement and subsequent nuclear rotation persist from leptotene/zygotene to pachytene, and then decline in diplotene stage concomitant with the liberation of SUN1 from telomeres. Further, during bouquet stage, telomeres are constrained near the MTOC, resulting in the transient suppression of telomere mobility and nuclear rotation. MTs are responsible for these movements by forming cable-like structures on the NE, and, probably, by facilitating the rail-tacking movements of telomeres on the MT cables. In contrast, actin regulates the oscillatory changes in nuclear shape. Our data provide the mechanical scheme for meiotic chromosome movement throughout prophase I in mammals.

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Stable MTOCs positioning during rapid chromosome movements.A, Time-lapse images (30 sec intervals) of spermatocytes (17 dpp) expressing GFP-TRF1 and GFP-SCP3 showing the “bouquet-like” configuration. Whole images are in S6 Movie. The graph shows the quantification of telomere velocities in bouquet stage (S5B Figure and S8 Movie). Three clustered and 10 cluster-free telomeres were traced for 10 continuous time-points, and the 3-dimensional velocities for each time-point interval are plotted. The bars represent average values. Statistical significance (TTEST, two-tailed) was assessed (*P<0.0005). B, Spermatocytes stained for SCP3 (blue), γ-Tubulin (green) and TRF1 (red). C, Time-lapse images (30 sec intervals) of spermatocytes expressing GFP-γ-Tubulin. Arrowheads indicate the positions of punctate GFP-γ-Ttubulin. Asterisks indicate identical heterochromatin. Whole images are in S7 Movie. Bars, 5 µm.
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pgen-1004821-g005: Stable MTOCs positioning during rapid chromosome movements.A, Time-lapse images (30 sec intervals) of spermatocytes (17 dpp) expressing GFP-TRF1 and GFP-SCP3 showing the “bouquet-like” configuration. Whole images are in S6 Movie. The graph shows the quantification of telomere velocities in bouquet stage (S5B Figure and S8 Movie). Three clustered and 10 cluster-free telomeres were traced for 10 continuous time-points, and the 3-dimensional velocities for each time-point interval are plotted. The bars represent average values. Statistical significance (TTEST, two-tailed) was assessed (*P<0.0005). B, Spermatocytes stained for SCP3 (blue), γ-Tubulin (green) and TRF1 (red). C, Time-lapse images (30 sec intervals) of spermatocytes expressing GFP-γ-Tubulin. Arrowheads indicate the positions of punctate GFP-γ-Ttubulin. Asterisks indicate identical heterochromatin. Whole images are in S7 Movie. Bars, 5 µm.

Mentions: During the course of time-lapse imaging, telomeres and heterochromatin gathered in a limited region on the NE, forming a “bouquet-like” arrangement (Fig. 5A and S6 Movie). The mobilities of clustered telomeres were apparently diminished, while cluster-free telomeres still moved rapidly in the same cell (Fig. 5A, right) (S5B Figure and S8 Movie) suggesting that telomere movements are locally constrained. Further, the polarized asymmetric distribution of telomeres and heterochromatin in bouquet stage persists throughout the time-lapse analysis, suggesting that the overall rotational movement is also largely suppressed (Fig. 5A, S5B Figure and S6 and S8 Movies). These results contrast with those for S. pombe, in which all telomeres are clustered near the spindle pole body (SPB/centrosome) forming bouquet-like arrangements, and the entire nucleus moves rapidly accompanying the bouquet arrangements throughout meiotic prophase I [3], [31].


The dissection of meiotic chromosome movement in mice using an in vivo electroporation technique.

Shibuya H, Morimoto A, Watanabe Y - PLoS Genet. (2014)

Stable MTOCs positioning during rapid chromosome movements.A, Time-lapse images (30 sec intervals) of spermatocytes (17 dpp) expressing GFP-TRF1 and GFP-SCP3 showing the “bouquet-like” configuration. Whole images are in S6 Movie. The graph shows the quantification of telomere velocities in bouquet stage (S5B Figure and S8 Movie). Three clustered and 10 cluster-free telomeres were traced for 10 continuous time-points, and the 3-dimensional velocities for each time-point interval are plotted. The bars represent average values. Statistical significance (TTEST, two-tailed) was assessed (*P<0.0005). B, Spermatocytes stained for SCP3 (blue), γ-Tubulin (green) and TRF1 (red). C, Time-lapse images (30 sec intervals) of spermatocytes expressing GFP-γ-Tubulin. Arrowheads indicate the positions of punctate GFP-γ-Ttubulin. Asterisks indicate identical heterochromatin. Whole images are in S7 Movie. Bars, 5 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263375&req=5

pgen-1004821-g005: Stable MTOCs positioning during rapid chromosome movements.A, Time-lapse images (30 sec intervals) of spermatocytes (17 dpp) expressing GFP-TRF1 and GFP-SCP3 showing the “bouquet-like” configuration. Whole images are in S6 Movie. The graph shows the quantification of telomere velocities in bouquet stage (S5B Figure and S8 Movie). Three clustered and 10 cluster-free telomeres were traced for 10 continuous time-points, and the 3-dimensional velocities for each time-point interval are plotted. The bars represent average values. Statistical significance (TTEST, two-tailed) was assessed (*P<0.0005). B, Spermatocytes stained for SCP3 (blue), γ-Tubulin (green) and TRF1 (red). C, Time-lapse images (30 sec intervals) of spermatocytes expressing GFP-γ-Tubulin. Arrowheads indicate the positions of punctate GFP-γ-Ttubulin. Asterisks indicate identical heterochromatin. Whole images are in S7 Movie. Bars, 5 µm.
Mentions: During the course of time-lapse imaging, telomeres and heterochromatin gathered in a limited region on the NE, forming a “bouquet-like” arrangement (Fig. 5A and S6 Movie). The mobilities of clustered telomeres were apparently diminished, while cluster-free telomeres still moved rapidly in the same cell (Fig. 5A, right) (S5B Figure and S8 Movie) suggesting that telomere movements are locally constrained. Further, the polarized asymmetric distribution of telomeres and heterochromatin in bouquet stage persists throughout the time-lapse analysis, suggesting that the overall rotational movement is also largely suppressed (Fig. 5A, S5B Figure and S6 and S8 Movies). These results contrast with those for S. pombe, in which all telomeres are clustered near the spindle pole body (SPB/centrosome) forming bouquet-like arrangements, and the entire nucleus moves rapidly accompanying the bouquet arrangements throughout meiotic prophase I [3], [31].

Bottom Line: Further, during bouquet stage, telomeres are constrained near the MTOC, resulting in the transient suppression of telomere mobility and nuclear rotation.In contrast, actin regulates the oscillatory changes in nuclear shape.Our data provide the mechanical scheme for meiotic chromosome movement throughout prophase I in mammals.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo, Japan.

ABSTRACT
During meiosis, the rapid movement of telomeres along the nuclear envelope (NE) facilitates pairing/synapsis of homologous chromosomes. In mammals, the mechanical properties of chromosome movement and the cytoskeletal structures responsible for it remain poorly understood. Here, applying an in vivo electroporation (EP) technique in live mouse testis, we achieved the quick visualization of telomere, chromosome axis and microtubule organizing center (MTOC) movements. For the first time, we defined prophase sub-stages of live spermatocytes morphologically according to GFP-TRF1 and GFP-SCP3 signals. We show that rapid telomere movement and subsequent nuclear rotation persist from leptotene/zygotene to pachytene, and then decline in diplotene stage concomitant with the liberation of SUN1 from telomeres. Further, during bouquet stage, telomeres are constrained near the MTOC, resulting in the transient suppression of telomere mobility and nuclear rotation. MTs are responsible for these movements by forming cable-like structures on the NE, and, probably, by facilitating the rail-tacking movements of telomeres on the MT cables. In contrast, actin regulates the oscillatory changes in nuclear shape. Our data provide the mechanical scheme for meiotic chromosome movement throughout prophase I in mammals.

Show MeSH
Related in: MedlinePlus