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Greenblatt EJ, Obniski R, Mical C, Spradling AC. Prolonged ovarian storage of mature Drosophila oocytes dramatically increases meiotic spindle instability. eLife 2019; 8:49455. [PMID: 31755866 PMCID: PMC6905857 DOI: 10.7554/elife.49455] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 11/17/2019] [Indexed: 12/21/2022] Open
Abstract
Human oocytes frequently generate aneuploid embryos that subsequently miscarry. In contrast, Drosophila oocytes from outbred laboratory stocks develop fully regardless of maternal age. Since mature Drosophila oocytes are not extensively stored in the ovary under laboratory conditions like they are in the wild, we developed a system to investigate how storage affects oocyte quality. The developmental capacity of stored mature Drosophila oocytes decays in a precise manner over 14 days at 25°C. These oocytes are transcriptionally inactive and persist using ongoing translation of stored mRNAs. Ribosome profiling revealed a progressive 2.3-fold decline in average translational efficiency during storage that correlates with oocyte functional decay. Although normal bipolar meiotic spindles predominate during the first week, oocytes stored for longer periods increasingly show tripolar, monopolar and other spindle defects, and give rise to embryos that fail to develop due to aneuploidy. Thus, meiotic chromosome segregation in mature Drosophila oocytes is uniquely sensitive to prolonged storage. Our work suggests the chromosome instability of human embryos could be mitigated by reducing the period of time mature human oocytes are stored in the ovary prior to ovulation.
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Affiliation(s)
- Ethan J Greenblatt
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Rebecca Obniski
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Claire Mical
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute Research Laboratories, Carnegie Institution for Science, Baltimore, United States
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Oliver TR, Feingold E, Yu K, Cheung V, Tinker S, Yadav-Shah M, Masse N, Sherman SL. New insights into human nondisjunction of chromosome 21 in oocytes. PLoS Genet 2008; 4:e1000033. [PMID: 18369452 PMCID: PMC2265487 DOI: 10.1371/journal.pgen.1000033] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Accepted: 02/11/2008] [Indexed: 11/18/2022] Open
Abstract
Nondisjunction of chromosome 21 is the leading cause of Down syndrome. Two risk factors for maternal nondisjunction of chromosome 21 are increased maternal age and altered recombination. In order to provide further insight on mechanisms underlying nondisjunction, we examined the association between these two well established risk factors for chromosome 21 nondisjunction. In our approach, short tandem repeat markers along chromosome 21 were genotyped in DNA collected from individuals with free trisomy 21 and their parents. This information was used to determine the origin of the nondisjunction error and the maternal recombination profile. We analyzed 615 maternal meiosis I and 253 maternal meiosis II cases stratified by maternal age. The examination of meiosis II errors, the first of its type, suggests that the presence of a single exchange within the pericentromeric region of 21q interacts with maternal age-related risk factors. This observation could be explained in two general ways: 1) a pericentromeric exchange initiates or exacerbates the susceptibility to maternal age risk factors or 2) a pericentromeric exchange protects the bivalent against age-related risk factors allowing proper segregation of homologues at meiosis I, but not segregation of sisters at meiosis II. In contrast, analysis of maternal meiosis I errors indicates that a single telomeric exchange imposes the same risk for nondisjunction, irrespective of the age of the oocyte. Our results emphasize the fact that human nondisjunction is a multifactorial trait that must be dissected into its component parts to identify specific associated risk factors.
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Affiliation(s)
- Tiffany Renee Oliver
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America.
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Abstract
Molecular motors are a fascinating group of proteins that have vital roles in a huge variety of cellular processes. They all share the ability to produce force through the hydrolysis of adenosine triphosphate, and fall into classes groups: the kinesins, myosins and the dyneins. The kinesin superfamily itself can be split into three major groups depending on the position of the motor domain, which is localized N-terminally, C-terminally, or internally. This review focuses on the N-terminal kinesins, providing a brief overview of their roles within the cell, and illustrating recent key developments in our understanding of how these proteins function.
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Affiliation(s)
- Marcin J Wozniak
- University of Manchester, School of Biological Sciences, The Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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Abstract
In this review, we describe the pathway for generating meiotic crossovers in Drosophila melanogaster females and how these events ensure the segregation of homologous chromosomes. As appears to be common to meiosis in most organisms, recombination is initiated with a double-strand break (DSB). The interesting differences between organisms appear to be associated with what chromosomal events are required for DSBs to form. In Drosophila females, the synaptonemal complex is required for most DSB formation. The repair of these breaks requires several DSB repair genes, some of which are meiosis-specific, and defects at this stage can have effects downstream on oocyte development. This has been suggested to result from a checkpoint-like signaling between the oocyte nucleus and gene products regulating oogenesis. Crossovers result from genetically controlled modifications to the DSB repair pathway. Finally, segregation of chromosomes joined by a chiasma requires a bipolar spindle. At least two kinesin motor proteins are required for the assembly of this bipolar spindle, and while the meiotic spindle lacks traditional centrosomes, some centrosome components are found at the spindle poles.
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Affiliation(s)
- Kim S McKim
- Waksman Institute and Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8020, USA.
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Marcus AI, Li W, Ma H, Cyr RJ. A kinesin mutant with an atypical bipolar spindle undergoes normal mitosis. Mol Biol Cell 2003; 14:1717-26. [PMID: 12686621 PMCID: PMC153134 DOI: 10.1091/mbc.e02-09-0586] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Motor proteins have been implicated in various aspects of mitosis, including spindle assembly and chromosome segregation. Here, we show that acentrosomal Arabidopsis cells that are mutant for the kinesin, ATK1, lack microtubule accumulation at the predicted spindle poles during prophase and have reduced spindle bipolarity during prometaphase. Nonetheless, all abnormalities are rectified by anaphase and chromosome segregation appears normal. We conclude that ATK1 is required for normal microtubule accumulation at the spindle poles during prophase and possibly functions in spindle assembly during prometaphase. Because aberrant spindle morphology in these mutants is resolved by anaphase, we postulate that mitotic plant cells contain an error-correcting mechanism. Moreover, ATK1 function seems to be dosage-dependent, because cells containing one wild-type allele take significantly longer to proceed to anaphase as compared with cells containing two wild-type alleles.
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Affiliation(s)
- A I Marcus
- The Pennsylvania State University, Department of Biology, 208 Mueller Laboratory, University Park, Pennsylvania 16801, USA
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Zwick ME, Salstrom JL, Langley CH. Genetic variation in rates of nondisjunction: association of two naturally occurring polymorphisms in the chromokinesin nod with increased rates of nondisjunction in Drosophila melanogaster. Genetics 1999; 152:1605-14. [PMID: 10430586 PMCID: PMC1460721 DOI: 10.1093/genetics/152.4.1605] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The oötid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations.
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Affiliation(s)
- M E Zwick
- Center for Population Biology, University of California, Davis, California 95616, USA.
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Schramm DD, Collins HE, Hawley RS, German JB. Unaltered meiotic chromosome segregation in Drosophila melanogaster raised on a 5% quercetin diet. Food Chem Toxicol 1998; 36:585-9. [PMID: 9687965 DOI: 10.1016/s0278-6915(98)00013-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Flavonoid plant pigments are an integral part of the human diet. Although potentially negative mitotic effects of flavonoids have been observed in model organisms, investigation into meiotic effects of flavonoids has been neglected. As flavonoids affect cell signalling and DNA replication, and because the flavonoid content of the human food supply is being increased, determining the effects of flavonoids on meiotic fidelity is important. Here, the effect of the human food supply's most prevalent flavonoid, quercetin, on the level of meiotic recombination and the amount of X and 4th chromosome non-disjunction in Drosophila melanogaster females was determined. This model organism was chosen since Drosophila melanogaster and Homo sapiens share a remarkable number of commonalities in the meiotic processes of oogenesis and because genetic techniques allow a detailed analysis of meiotic processes in Drosophila. No significant effect on either non-disjunction levels or the percentage distribution of exchange bivalents was observed. A significant effect was observed on the number of offspring; F1 and F2 generations of flies raised on a quercetin diet produced over 10% more progeny than flies raised on a control diet. In this investigation, high quercetin consumption by Drosophila melanogaster females did not pose a threat to meiotic fidelity.
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Affiliation(s)
- D D Schramm
- Department of Food Science and Technology, University of California at Davis, 95616, USA
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Koehler KE, Boulton CL, Collins HE, French RL, Herman KC, Lacefield SM, Madden LD, Schuetz CD, Hawley RS. Spontaneous X chromosome MI and MII nondisjunction events in Drosophila melanogaster oocytes have different recombinational histories. Nat Genet 1996; 14:406-14. [PMID: 8944020 DOI: 10.1038/ng1296-406] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Recent studies of human oocytes have demonstrated an enrichment for distal exchanges among meiosis I (MI) nondisjunction events and for proximal exchanges among meiosis II (MII) events. Our characterization of 103 cases of spontaneous X chromosome nondisjunction in Drosophila oocytes strongly parallels these observations. The recombinational histories of MI (97/103) and MII (6/103) nondisjunctional ova were strikingly different. MI nondisjunction occurred primarily in oocytes with non-exchange X chromosomes; of the new nondisjoining exchange bivalents, most carried distal crossovers. Thus, spontaneous MI nondisjunction reflects the failure of the achiasmate segregation systems. MII nondisjunction occurred only in oocytes with proximal exchanges. We propose several models to explain how very proximal exchanges might impair proper segregation.
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Affiliation(s)
- K E Koehler
- Department of Genetics, University of California at Davis 95616, USA
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Tokai N, Fujimoto-Nishiyama A, Toyoshima Y, Yonemura S, Tsukita S, Inoue J, Yamamota T. Kid, a novel kinesin-like DNA binding protein, is localized to chromosomes and the mitotic spindle. EMBO J 1996; 15:457-67. [PMID: 8599929 PMCID: PMC449964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Microtubule-associated motor proteins are thought to be involved in spindle formation and chromosome movements in mitosis/meiosis. We have molecularly cloned cDNAs for a gene that codes for a novel member of the kinesin family of proteins. Nucleotide sequencing reveals that the predicted gene product is a 73 kDa protein and is related to some extent to the Drosophila node gene product, which is involved in chromosomal segregation during meiosis. A sequence similar to the microtubule binding motor domain of kinesin is present in the N-terminal half of the protein, and its ability to bind to microtubules is demonstrated. Furthermore we show that its C-terminal half contains a putative nuclear localization signal similar to that of Jun and is able to bind to DNA. Accordingly, the protein was termed Kid (kinesin-like DNA binding protein). Indirect immunofluorescence studies show that Kid colocalizes with mitotic chromosomes and that it is enriched in the kinetochore at anaphase. Thus, we propose that Kid might play a role(s) in regulating the chromosomal movement along microtubules during mitosis.
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Affiliation(s)
- N Tokai
- The Institute of Medical Science, The University of Tokyo, Japan
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Abstract
The chromosomes which segregate in anaphase I of meiosis are usually physically bound together through chiasmata. This association is necessary for proper segregation, since univalents sort independently from one another in the first meiotic division and this frequently leads to genetically unbalanced offspring. There are, however, a number of species where genetic exchanges in the form of meiotic cross-overs, the prerequisite of the formation of chiasmata, are routinely missing in one sex or between specific chromosomes. These species nevertheless manage to segregate these non-exchange chromosomes. There are four direct modes for associating achiasmatic chromosomes: (a) modified SC, (b) adhesion of chromatids comparable to somatic pairing, (c) 'stickiness' of heterochromatin or (d) specific 'segregation bodies', consisting of material structurally different from chromatin. There is also the possibility that the spindle-possibly joining forces with the kinetochores--carries out the faithful segregation of univalents which are not directly physically attached to one another. Finally, amphitelic orientation of univalents in metaphase I and pairing of the chromatids in meiosis II appear to ensure correct segregation as well.
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Affiliation(s)
- K W Wolf
- Institut für Biologie der Medizinischen Universität zu Lübeck, Deutschland
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Affiliation(s)
- C Gonzalez
- Department of Anatomy and Physiology, University of Dundee, Scotland
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Hawley RS, Irick H, Zitron AE, Haddox DA, Lohe A, New C, Whitley MD, Arbel T, Jang J, McKim K. There are two mechanisms of achiasmate segregation in Drosophila females, one of which requires heterochromatic homology. DEVELOPMENTAL GENETICS 1992; 13:440-67. [PMID: 1304424 DOI: 10.1002/dvg.1020130608] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
There are numerous examples of the regular segregation of achiasmate chromosomes at meiosis I in Drosophila melanogaster females. Classically, the choice of achiasmate segregational partners has been thought to be independent of homology, but rather made on the basis of availability or similarities in size and shape. To the contrary, we show here that heterochromatic homology plays a primary role in ensuring the proper segregation of achiasmate homologs. We observe that the heterochromatin of chromosome 4 functions as, or contains, a meiotic pairing site. We show that free duplications carrying the 4th chromosome pericentric heterochromatin induce high frequencies of 4th chromosome nondisjunction regardless of their size. Moreover, a duplication from which some of the 4th chromosome heterochromatin has been removed is unable to induce 4th chromosome nondisjunction. Similarly, in the absence of either euchromatic homology or a size similarity, duplications bearing the X chromosome heterochromatin also disrupt the segregation of two achiasmate X chromosome centromeres. Although heterochromatic regions are sufficient to conjoin nonexchange homologues, we confirm that the segregation of heterologous chromosomes is determined by size, shape, and availability. The meiotic mutation Axs differentiates between these two processes of achiasmate centromere coorientation by disrupting only the homology-dependent mechanism. Thus there are two different mechanisms by which achiasmate segregational partners are chosen. We propose that the absence of diplotene-diakinesis during female meiosis allows heterochromatic pairings to persist until prometaphase and thus to co-orient homologous centromeres. We also propose that heterologous disjunctions result from a separate and homology-independent process that likely occurs during prometaphase. The latter process, which may not require the physical association of segregational partners, is similar to those observed in many insects, in Saccharomyces cerevisiae and in C. elegans males. We also suggest that the physical basis of this process may reflect known properties of the Drosophila meiotic spindle.
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Affiliation(s)
- R S Hawley
- Department of Genetics, University of California, Davis
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