File:Age-related chromosome segregation errors during MI model.jpg: Difference between revisions

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Premature bivalent separation into univalents precedes age-related chromosome segregation errors during Meiosis i (MI)

Bivalents with weakened cohesion in aged oocytes undergo hyperstretching and separation into univalents by microtubule-mediated bipolar spindle forces.

This bipolar forces in turn biorient the sister kinetochores (KTs) of the univalents. The univalents are therefore strongly biased towards predivision of sister chromatids, including balanced predivision. After balanced predivision during MI, the chromatids undergo random segregation during MII.

Links: Oocyte Development | Meiosis | Trisomy 21

Reference

Sakakibara Y, Hashimoto S, Nakaoka Y, Kouznetsova A, Höög C & Kitajima TS. (2015). Bivalent separation into univalents precedes age-related meiosis I errors in oocytes. Nat Commun , 6, 7550. PMID: 26130582 DOI.

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Figure 5 altered in size and labelling. Above text from figure legend.

Cite this page: Hill, M.A. (2024, June 26) Embryology Age-related chromosome segregation errors during MI model.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Age-related_chromosome_segregation_errors_during_MI_model.jpg

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-Premature bivalent separation into univalents precedes age-related chromosome segregation errors during MI.
+==Premature bivalent separation into univalents precedes age-related chromosome segregation errors during Meiosis i (MI)==
-Bivalents with weakened cohesion in aged oocytes undergo hyperstretching and separation into univalents by microtubule-mediated bipolar spindle forces. This bipolar forces in turn biorient the sister KTs of the univalents. The univalents are therefore strongly biased towards predivision of sister chromatids, including balanced predivision. After balanced predivision during MI, the chromatids undergo random segregation during MII.
+Bivalents with weakened cohesion in aged oocytes undergo hyperstretching and separation into univalents by microtubule-mediated bipolar spindle forces.
+This bipolar forces in turn biorient the sister kinetochores (KTs) of the univalents. The univalents are therefore strongly biased towards predivision of sister chromatids, including balanced predivision. After balanced predivision during MI, the chromatids undergo random segregation during MII.
+:'''Links:''' [[Oocyte Development]] | [[Cell Division - Meiosis|Meiosis]] | [[Trisomy 21]]
 ===Reference===
+{{#pmid:26130582}}
-PMID 26130582
 ====Copyright====
 This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
+Figure 5 altered in size and labelling. Above text from figure legend.
-Nat Commun. 2015 Jul 1;6:7550. doi: 10.1038/ncomms8550.
-Bivalent separation into univalents precedes age-related meiosis I errors in oocytes.
-Sakakibara Y1, Hashimoto S2, Nakaoka Y2, Kouznetsova A3, Höög C3, Kitajima TS1.
-Author information
-Abstract
-The frequency of chromosome segregation errors during meiosis I (MI) in oocytes increases with age. The two-hit model suggests that errors are caused by the combination of a first hit that creates susceptible crossover configurations and a second hit comprising an age-related reduction in chromosome cohesion. This model predicts an age-related increase in univalents, but direct evidence of this phenomenon as a major cause of segregation errors has been lacking. Here, we provide the first live analysis of single chromosomes undergoing segregation errors during MI in the oocytes of naturally aged mice. Chromosome tracking reveals that 80% of the errors are preceded by bivalent separation into univalents. The set of the univalents is biased towards balanced and unbalanced predivision of sister chromatids during MI. Moreover, we find univalents predisposed to predivision in human oocytes. This study defines premature bivalent separation into univalents as the primary defect responsible for age-related aneuploidy.
-PMID: 26130582
+{{Footer}}
-Figure 5:
+[[Category:Meiosis]]