Limits...
SOLO: a meiotic protein required for centromere cohesion, coorientation, and SMC1 localization in Drosophila melanogaster.

Yan R, Thomas SE, Tsai JH, Yamada Y, McKee BD - J. Cell Biol. (2010)

Bottom Line: Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages.SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin.The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.

ABSTRACT
Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

Show MeSH

Related in: MedlinePlus

Sister chromatid cohesion and homologue pairing at prometaphase I in solo; +, +; snm, and solo; snm mutants. X and Y chromosomes were recognized by probes against the 359 bp (green) and AATAC (red) satellite DNA repeats, respectively. DNA was stained with DAPI. Sum projections of 3D-deconvolved z series stacks were performed. (A) Quantification of cohesion and pairing patterns. Table shows the percent and number of nuclei (in parentheses) exhibiting indicated pairing and cohesion patterns. (B) Representative images. Bivalents versus univalents were judged from DAPI panels. Presence or absence of cohesion was based on separation between sister chromatids as judged from DAPI images and on separation between sister FISH signals. Bars, 5 µm. (C) Quantification of 359 bp signal separation patterns. See Table II for genotypes.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2819681&req=5

fig3: Sister chromatid cohesion and homologue pairing at prometaphase I in solo; +, +; snm, and solo; snm mutants. X and Y chromosomes were recognized by probes against the 359 bp (green) and AATAC (red) satellite DNA repeats, respectively. DNA was stained with DAPI. Sum projections of 3D-deconvolved z series stacks were performed. (A) Quantification of cohesion and pairing patterns. Table shows the percent and number of nuclei (in parentheses) exhibiting indicated pairing and cohesion patterns. (B) Representative images. Bivalents versus univalents were judged from DAPI panels. Presence or absence of cohesion was based on separation between sister chromatids as judged from DAPI images and on separation between sister FISH signals. Bars, 5 µm. (C) Quantification of 359 bp signal separation patterns. See Table II for genotypes.

Mentions: To examine centromere cohesion when orientation patterns are established, we extended the FISH analysis to earlier stages of meiosis I. 43% of solo prometaphase I spermatocytes showed two separate 359 bp signals compared with only 16% of WT spermatocytes (Fig. 3). The observation of a low level of separation of sister 359 bp loci in WT is consistent with previous results (Balicky et al., 2002). It could be due either to the FISH squash procedure or the fact that the 359 bp repeats are outside, albeit adjacent to, the centromere proper. Nevertheless, our results indicate that cohesion proximal to the X centromere is reduced in solo mutants by 27% more than in WT spermatocytes. Similar observations were obtained using a probe against the dodeca satellite locus, a repetitive locus near the centromere of chromosome 3 (Fig. S2). At prometaphase I, WT third chromosome bivalents typically exhibited only two dodeca signals, whereas four signals were typically present in solo bivalents at the same stage. At anaphase I, one dodeca signal was present at each pole in WT, but two signals were usually seen at each pole in solo mutants.


SOLO: a meiotic protein required for centromere cohesion, coorientation, and SMC1 localization in Drosophila melanogaster.

Yan R, Thomas SE, Tsai JH, Yamada Y, McKee BD - J. Cell Biol. (2010)

Sister chromatid cohesion and homologue pairing at prometaphase I in solo; +, +; snm, and solo; snm mutants. X and Y chromosomes were recognized by probes against the 359 bp (green) and AATAC (red) satellite DNA repeats, respectively. DNA was stained with DAPI. Sum projections of 3D-deconvolved z series stacks were performed. (A) Quantification of cohesion and pairing patterns. Table shows the percent and number of nuclei (in parentheses) exhibiting indicated pairing and cohesion patterns. (B) Representative images. Bivalents versus univalents were judged from DAPI panels. Presence or absence of cohesion was based on separation between sister chromatids as judged from DAPI images and on separation between sister FISH signals. Bars, 5 µm. (C) Quantification of 359 bp signal separation patterns. See Table II for genotypes.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2819681&req=5

fig3: Sister chromatid cohesion and homologue pairing at prometaphase I in solo; +, +; snm, and solo; snm mutants. X and Y chromosomes were recognized by probes against the 359 bp (green) and AATAC (red) satellite DNA repeats, respectively. DNA was stained with DAPI. Sum projections of 3D-deconvolved z series stacks were performed. (A) Quantification of cohesion and pairing patterns. Table shows the percent and number of nuclei (in parentheses) exhibiting indicated pairing and cohesion patterns. (B) Representative images. Bivalents versus univalents were judged from DAPI panels. Presence or absence of cohesion was based on separation between sister chromatids as judged from DAPI images and on separation between sister FISH signals. Bars, 5 µm. (C) Quantification of 359 bp signal separation patterns. See Table II for genotypes.
Mentions: To examine centromere cohesion when orientation patterns are established, we extended the FISH analysis to earlier stages of meiosis I. 43% of solo prometaphase I spermatocytes showed two separate 359 bp signals compared with only 16% of WT spermatocytes (Fig. 3). The observation of a low level of separation of sister 359 bp loci in WT is consistent with previous results (Balicky et al., 2002). It could be due either to the FISH squash procedure or the fact that the 359 bp repeats are outside, albeit adjacent to, the centromere proper. Nevertheless, our results indicate that cohesion proximal to the X centromere is reduced in solo mutants by 27% more than in WT spermatocytes. Similar observations were obtained using a probe against the dodeca satellite locus, a repetitive locus near the centromere of chromosome 3 (Fig. S2). At prometaphase I, WT third chromosome bivalents typically exhibited only two dodeca signals, whereas four signals were typically present in solo bivalents at the same stage. At anaphase I, one dodeca signal was present at each pole in WT, but two signals were usually seen at each pole in solo mutants.

Bottom Line: Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages.SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin.The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.

ABSTRACT
Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

Show MeSH
Related in: MedlinePlus