Active role of lagging chromosomes in spindle collapse as revealed by live phase contrast and tubulin immunostaining in grasshopper spermatocytes

Rebollo, Elena; Arana, P.

doi:10.1007/s004120100147

Cited by 5 publications

(7 citation statements)

References 36 publications

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“…3 g-h, 9 b). This was consistent with the first alternative above, i.e., aberrant bipolar orientation of sister kinetochores in univalents coupled with loss of centromeric cohesion in early anaphase I [ 28 , 44 ]. A smaller frequency of hybrid-33 PMCs showed a complete failure of anaphase I segregation, resulting in a completely restituted nucleus (AI-Type3, Fig.…”

Section: Discussionsupporting

confidence: 90%

“…3 l-m). This was consistent with the alternative model where the removal of centromeric cohesion in univalents was delayed until late anaphase I, provoking spindle collapse and a restituted nucleus [ 28 , 33 , 44 – 46 ]. The intermediate AI- and MII-Type 2 phenotypes (Figs.…”

Section: Discussionsupporting

confidence: 90%

“…Consequently, sister kinetochores attach to opposite poles [ 8 , 10 , 28 , 41 – 43 ]. If the cohesion is removed early, at the transition of metaphase I to anaphase I, univalents display premature separation of sister chromatids and undergo equational division [ 28 , 33 , 44 ]. Alternatively, if the removal of cohesion is incomplete or the removal continues during anaphase I, the spindle collapses due to opposing forces between the spindle microtubules and the remnant kinetochore cohesion, laggards occur, and an unreduced restitution nucleus is generated [ 28 , 29 , 44 , 45 ].…”

Section: Discussionmentioning

confidence: 99%

“…The intermediate AI- and MII-Type 2 phenotypes (Figs. 3 j-k, p-q) observed in a few PMCs are difficult to classify as they may have several possible causes, including incomplete spindle collapse [ 44 ].…”

Section: Discussionmentioning

confidence: 99%

“…The simultaneous equational division of univalents and reductional division of bivalents and multivalents on the same spindle, as observed in this and other studies, can thus be understood. As noted earlier, variability in the dissolution of centromeric cohesion in univalents during meiosis I may lead to segregational failure [ 44 , 45 ]. Several studies in the Triticeae and in grasshoppers have shown that the greater the number of univalents, the greater the chance of spindle collapse leading to meiotic restitution and unreduced gametes [ 29 , 34 , 44 ].…”

Section: Discussionmentioning

confidence: 99%

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Asynapsis and unreduced gamete formation in a Trifolium interspecific hybrid

et al. 2022

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Background Unreduced gametes, a driving force in the widespread polyploidization and speciation of flowering plants, occur relatively frequently in interspecific or intergeneric hybrids. Studies of the mechanisms leading to 2n gamete formation, mainly in the wheat tribe Triticeae have shown that unreductional meiosis is often associated with chromosome asynapsis during the first meiotic division. The present study explored the mechanisms of meiotic nonreduction leading to functional unreduced gametes in an interspecific Trifolium (clover) hybrid with three sub-genomes from T. ambiguum and one sub-genome from T. occidentale. Results Unreductional meiosis leading to 2n gametes occurred when there was a high frequency of asynapsis during the first meiotic division. In this hybrid, approximately 39% of chromosomes were unpaired at metaphase I. Within the same cell at anaphase I, sister chromatids of univalents underwent precocious separation and formed laggard chromatids whereas paired chromosomes segregated without separation of sister chromatids as in normal meiosis. This asynchrony was frequently accompanied by incomplete or no movement of chromosomes toward the poles and restitution leading to unreduced chromosome constitutions. Reductional meiosis was restored in progeny where asynapsis frequencies were low. Two progeny plants with approximately 5 and 7% of unpaired chromosomes at metaphase I showed full restoration of reductional meiosis. Conclusions The study revealed that formation of 2n gametes occurred when asynapsis (univalent) frequency at meiosis I was high, and that normal gamete production was restored in the next generation when asynapsis frequencies were low. Asynapsis-dependent 2n gamete formation, previously supported by evidence largely from wheat and its relatives and grasshopper, is also applicable to hybrids from the dicotyledonous plant genus Trifolium. The present results align well with those from these widely divergent organisms and strongly suggest common molecular mechanisms involved in unreduced gamete formation.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Asynapsis and unreduced gamete formation in a Trifolium interspecific hybrid

et al. 2022

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Breaking down taxonomic barriers in polyploidy research

Mable

2003

Trends in Plant Science

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B chromosomes: the troubles of integration

Granado¹,

Rebollo²,

Sánchez³

et al. 2004

Cytogenet Genome Res

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Starting with a spontaneous B-A centric fusion found in a natural population of the grasshopper Eyprepocnemis plorans, we have obtained different strains carrying the rearrangement in various conditions and doses. Using this material, we have analyzed the meiotic behavior of the translocated chromosome in living cultured spermatocytes, simulating the successive steps of a hypothetical process of integration of a B chromosome into the standard genome via B-A centric fusion. Remarkably, the behavior of fusion heterozygotes, the initial step of the integration process, is much more regular than that of any other configuration, including homozygotes. The reasons for the failure of B chromosome integration into the normal complement by translocation are discussed.

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Active role of lagging chromosomes in spindle collapse as revealed by live phase contrast and tubulin immunostaining in grasshopper spermatocytes

Cited by 5 publications

References 36 publications

Asynapsis and unreduced gamete formation in a Trifolium interspecific hybrid

Asynapsis and unreduced gamete formation in a Trifolium interspecific hybrid

Breaking down taxonomic barriers in polyploidy research

B chromosomes: the troubles of integration

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