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Ebrahimzadegan R, Fuchs J, Chen J, Schubert V, Meister A, Houben A, Mirzaghaderi G. Meiotic segregation and post-meiotic drive of the Festuca pratensis B chromosome. Chromosome Res 2023; 31:26. [PMID: 37658970 PMCID: PMC10474989 DOI: 10.1007/s10577-023-09728-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/13/2023] [Accepted: 07/19/2023] [Indexed: 09/05/2023]
Abstract
In many species, the transmission of B chromosomes (Bs) does not follow the Mendelian laws of equal segregation and independent assortment. This deviation results in transmission rates of Bs higher than 0.5, a process known as "chromosome drive". Here, we studied the behavior of the 103 Mbp-large B chromosome of Festuca pratensis during all meiotic and mitotic stages of microsporogenesis. Mostly, the B chromosome of F. pratensis segregates during meiosis like standard A chromosomes (As). In some cases, the B passes through meiosis in a non-Mendelian segregation leading to their accumulation already in meiosis. However, a true drive of the B happens during the first pollen mitosis, by which the B preferentially migrates to the generative nucleus. During second pollen mitosis, B divides equally between the two sperms. Despite some differences in the frequency of drive between individuals with different numbers of Bs, at least 82% of drive was observed. Flow cytometry-based quantification of B-containing sperm nuclei agrees with the FISH data.
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Affiliation(s)
- Rahman Ebrahimzadegan
- Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, 66177-15175, Iran
| | - Jörg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Jianyong Chen
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Armin Meister
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany.
| | - Ghader Mirzaghaderi
- Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, 66177-15175, Iran.
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Flynn JM, Hu KB, Clark AG. Three recent sex chromosome-to-autosome fusions in a Drosophila virilis strain with high satellite DNA content. Genetics 2023; 224:iyad062. [PMID: 37052958 PMCID: PMC10213488 DOI: 10.1093/genetics/iyad062] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/02/2022] [Accepted: 04/07/2023] [Indexed: 04/14/2023] Open
Abstract
The karyotype, or number and arrangement of chromosomes, has varying levels of stability across both evolution and disease. Karyotype changes often originate from DNA breaks near the centromeres of chromosomes, which generally contain long arrays of tandem repeats or satellite DNA. Drosophila virilis possesses among the highest relative satellite abundances of studied species, with almost half its genome composed of three related 7 bp satellites. We discovered a strain of D. virilis that we infer recently underwent three independent chromosome fusion events involving the X and Y chromosomes, in addition to one subsequent fission event. Here, we isolate and characterize the four different karyotypes we discovered in this strain which we believe demonstrates remarkable genome instability. We discovered that one of the substrains with an X-autosome fusion has an X-to-Y chromosome nondisjunction rate 20 × higher than the D. virilis reference strain (21% vs 1%). Finally, we found an overall higher rate of DNA breakage in the substrain with higher satellite DNA compared to a genetically similar substrain with less satellite DNA. This suggests that satellite DNA abundance may play a role in the risk of genome instability. Overall, we introduce a novel system consisting of a single strain with four different karyotypes, which we believe will be useful for future studies of genome instability, centromere function, and sex chromosome evolution.
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Affiliation(s)
- Jullien M Flynn
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
| | - Kevin B Hu
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Biotechnology Building Room 227, Ithaca, NY 14853, USA
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3
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Ma WJ, Knoles EM, Patch KB, Shoaib MM, Unckless RL. Hoisted with his own petard: How sex-ratio meiotic drive in Drosophila affinis creates resistance alleles that limit its spread. J Evol Biol 2022; 35:1765-1776. [PMID: 35997297 DOI: 10.1111/jeb.14077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/20/2022] [Accepted: 07/14/2022] [Indexed: 11/28/2022]
Abstract
Meiotic drivers are selfish genetic elements that tinker with gametogenesis to bias their own transmission into the next generation of offspring. Such tinkering can have significant consequences on gametogenesis and end up hampering the spread of the driver. In Drosophila affinis, sex-ratio meiotic drive is caused by an X-linked complex that, when in males with a susceptible Y chromosome, results in broods that are typically more than 95% female. Interestingly, D. affinis males lacking a Y chromosome (XO) are fertile and males with the meiotic drive X and no Y produce only sons-effectively reversing the sex-ratio effect. Here, we show that meiotic drive dramatically increases the rate of nondisjunction of the Y chromosome (at least 750X), meaning that the driver is creating resistant alleles through the process of driving. We then model how the O might influence the spread, dynamics and equilibrium of the sex-ratio X chromosome. We find that the O can prevent the spread or reduce the equilibrium frequency of the sex-ratio X chromosome, and it can even lead to oscillations in frequency. Finally, with reasonable parameters, the O is unlikely to lead to the loss of the Y chromosome, but we discuss how it might lead to sex-chromosome turnover indirectly.
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Affiliation(s)
- Wen-Juan Ma
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Emma M Knoles
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Kistie B Patch
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Murtaza M Shoaib
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
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Garribba L, Vogel I, Lerdrup M, Gonçalves Dinis MM, Ren L, Liu Y. Folate Deficiency Triggers the Abnormal Segregation of a Region With Large Cluster of CG-Rich Trinucleotide Repeats on Human Chromosome 2. Front Genet 2021; 12:695124. [PMID: 34276797 PMCID: PMC8281231 DOI: 10.3389/fgene.2021.695124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
Folate deficiency is associated with a broad range of human disorders, including anemia, fetal neural tube defects, age-associated dementia and several types of cancer. It is well established that a subgroup of rare fragile sites (RFSs) containing expanded CGG trinucleotide repeat (TNR) sequences display instability when cells are deprived of folate. However, given that folate sensitive RFSs exist in a very small percentage of the population, they are unlikely to be the cause of the widespread health problems associated with folate deficiency. We hypothesized that folate deficiency could specifically affect DNA replication at regions containing CG-rich repeat sequences. For this, we identified a region on human chromosome 2 (Chr2) comprising more than 300 CG-rich TNRs (termed “FOLD1”) by examining the human genome database. Via the analysis of chromosome shape and segregation in mitosis, we demonstrate that, when human cells are cultured under folate stress conditions, Chr2 is prone to display a “kink” or “bending” at FOLD1 in metaphase and nondisjunction in anaphase. Furthermore, long-term folate deprivation causes Chr2 aneuploidy. Our results provide new evidence on the abnormalities folate deficiency could cause in human cells. This could facilitate future studies on the deleterious health conditions associated with folate deficiency.
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Affiliation(s)
- Lorenza Garribba
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Ivan Vogel
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Mads Lerdrup
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Marisa M Gonçalves Dinis
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Liqun Ren
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Ying Liu
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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Blavet N, Yang H, Su H, Solanský P, Douglas RN, Karafiátová M, Šimková L, Zhang J, Liu Y, Hou J, Shi X, Chen C, El-Walid M, McCaw ME, Albert PS, Gao Z, Zhao C, Ben-Zvi G, Glick L, Kol G, Shi J, Vrána J, Šimková H, Lamb JC, Newton K, Dawe RK, Doležel J, Ji T, Baruch K, Cheng J, Han F, Birchler JA, Bartoš J. Sequence of the supernumerary B chromosome of maize provides insight into its drive mechanism and evolution. Proc Natl Acad Sci U S A 2021; 118:e2104254118. [PMID: 34088847 DOI: 10.1073/pnas.2104254118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
B chromosomes are enigmatic elements in thousands of plant and animal genomes that persist in populations despite being nonessential. They circumvent the laws of Mendelian inheritance but the molecular mechanisms underlying this behavior remain unknown. Here we present the sequence, annotation, and analysis of the maize B chromosome providing insight into its drive mechanism. The sequence assembly reveals detailed locations of the elements involved with the cis and trans functions of its drive mechanism, consisting of nondisjunction at the second pollen mitosis and preferential fertilization of the egg by the B-containing sperm. We identified 758 protein-coding genes in 125.9 Mb of B chromosome sequence, of which at least 88 are expressed. Our results demonstrate that transposable elements in the B chromosome are shared with the standard A chromosome set but multiple lines of evidence fail to detect a syntenic genic region in the A chromosomes, suggesting a distant origin. The current gene content is a result of continuous transfer from the A chromosomal complement over an extended evolutionary time with subsequent degradation but with selection for maintenance of this nonvital chromosome.
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Chernus JM, Sherman SL, Feingold E. Analyses stratified by maternal age and recombination further characterize genes associated with maternal nondisjunction of chromosome 21. Prenat Diagn 2021; 41:591-609. [PMID: 33596328 DOI: 10.1002/pd.5919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 01/17/2021] [Accepted: 02/02/2021] [Indexed: 12/22/2022]
Abstract
OBJECTIVE In our previous work, we performed the first genome-wide association study to find genetic risk factors for maternal nondisjunction of chromosome 21. The objective of the current work was to perform stratified analyses of the same dataset to further elucidate potential mechanisms of genetic risk factors. METHODS We focused on loci that were statistically significantly associated with maternal nondisjunction based on this same dataset in our previous study and performed stratified association analyses in seven subgroups defined by age and meiotic recombination profile. In each analysis, we contrasted a different subgroup of mothers with the same set of fathers, the mothers serving as cases (phenotype: meiotic nondisjunction of chromosome 21) and the fathers as controls. RESULTS Our stratified analyses identified several genes whose patterns of association are consistent with generalized effects across groups, as well as other genes that are consistent with specific effects in certain groups. CONCLUSIONS While our results are epidemiological in nature and cannot conclusively prove mechanisms, we identified a number of patterns that are consistent with specific mechanisms. In many cases those mechanisms are strongly supported by available literature on the associated genes.
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Affiliation(s)
- Jonathan M Chernus
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Stephanie L Sherman
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Eleanor Feingold
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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7
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Cherezov RO, Vorontsova JE, Simonova OB. TBP-Related Factor 2 as a Trigger for Robertsonian Translocations and Speciation. Int J Mol Sci 2020; 21:E8871. [PMID: 33238614 PMCID: PMC7700478 DOI: 10.3390/ijms21228871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 11/16/2022] Open
Abstract
Robertsonian (centric-fusion) translocation is the form of chromosomal translocation in which two long arms of acrocentric chromosomes are fused to form one metacentric. These translocations reduce the number of chromosomes while preserving existing genes and are considered to contribute to speciation. We asked whether hypomorphic mutations in genes that disrupt the formation of pericentromeric regions could lead to centric fusion. TBP-related factor 2 (Trf2) encodes an alternative general transcription factor. A decrease of TRF2 expression disrupts the structure of the pericentromeric regions and prevents their association into chromocenter. We revealed several centric fusions in two lines of Drosophila melanogaster with weak Trf2 alleles in genetic experiments. We performed an RNAi-mediated knock-down of Trf2 in Drosophila and S2 cells and demonstrated that Trf2 upregulates expression of D1-one of the major genes responsible for chromocenter formation and nuclear integrity in Drosophila. Our data, for the first time, indicate that Trf2 may be involved in transcription program responsible for structuring of pericentromeric regions and may contribute to new karyotypes formation in particular by promoting centric fusion. Insight into the molecular mechanisms of Trf2 function and its new targets in different tissues will contribute to our understanding of its phenomenon.
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Affiliation(s)
| | | | - Olga B. Simonova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Vavilova str. 26, 119991 Moscow, Russia; (R.O.C.); (J.E.V.)
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8
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Abstract
The term interchromosomal effect was originally used to describe a change in the distribution of exchange in the presence of an inversion. First characterized in the 1920s by early Drosophila researchers, it has been observed in multiple organisms. Nearly half a century later, the term began to appear in the human genetics literature to describe the hypothesis that parental chromosome differences, such as translocations or inversions, may increase the frequency of meiotic chromosome nondisjunction. Although it remains unclear if chromosome aberrations truly affect the segregation of structurally normal chromosomes in humans, the use of the term interchromosomal effect in this context persists. This article explores the history of the use of the term interchromosomal effect and discusses how chromosomes with structural aberrations are segregated during meiosis.
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Affiliation(s)
- Danny E Miller
- Department of Pediatrics, Division of Genetic Medicine, University of Washington and Seattle Children's Hospital, Seattle, WA 98105
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Hylton CA, Hansen K, Bourgeois A, Tomkiel Dean JE. Sex Chromosome Pairing Mediated by Euchromatic Homology in Drosophila Male Meiosis. Genetics 2020; 214:605-616. [PMID: 31915134 PMCID: PMC7054017 DOI: 10.1534/genetics.119.302936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/03/2020] [Indexed: 01/15/2023] Open
Abstract
Diploid germline cells must undergo two consecutive meiotic divisions before differentiating as haploid sex cells. During meiosis I, homologs pair and remain conjoined until segregation at anaphase. Drosophila melanogaster spermatocytes are unique in that the canonical events of meiosis I including synaptonemal complex formation, double-strand DNA breaks, and chiasmata are absent. Sex chromosomes pair at intergenic spacer sequences within the ribosomal DNA (rDNA). Autosomes pair at numerous euchromatic homologies, but not at heterochromatin, suggesting that pairing may be limited to specific sequences. However, previous work generated from genetic segregation assays or observations of late prophase I/prometaphase I chromosome associations fail to differentiate pairing from maintenance of pairing (conjunction). Here, we separately examined the capability of X euchromatin to pair and conjoin using an rDNA-deficient X and a series of Dp(1;Y) chromosomes. Genetic assays showed that duplicated X euchromatin can substitute for endogenous rDNA pairing sites. Segregation was not proportional to homology length, and pairing could be mapped to nonoverlapping sequences within a single Dp(1;Y) Using fluorescence in situ hybridization to early prophase I spermatocytes, we showed that pairing occurred with high fidelity at all homologies tested. Pairing was unaffected by the presence of X rDNA, nor could it be explained by rDNA magnification. By comparing genetic and cytological data, we determined that centromere proximal pairings were best at segregation. Segregation was dependent on the conjunction protein Stromalin in Meiosis, while the autosomal-specific Teflon was dispensable. Overall, our results suggest that pairing may occur at all homologies, but there may be sequence or positional requirements for conjunction.
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Affiliation(s)
- Christopher A Hylton
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - Katie Hansen
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - Andrew Bourgeois
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
| | - John E Tomkiel Dean
- Department of Biology, University of North Carolina, Greensboro, North Carolina 27402
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Chang YC, Khanal Lamichhane A, Kwon-Chung KJ. Cryptococcus neoformans, Unlike Candida albicans, Forms Aneuploid Clones Directly from Uninucleated Cells under Fluconazole Stress. mBio 2018; 9:e01290-18. [PMID: 30514783 DOI: 10.1128/mBio.01290-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heteroresistance to fluconazole (FLC) in Cryptococcus is a transient adaptive resistance which is lost upon release from the drug pressure. It is known that clones heteroresistant to FLC invariably contain disomic chromosomes, but how disomy is formed remains unclear. Previous reports suggested that the aneuploid heteroresistant colonies in Cryptococcus emerge from multinucleated cells, resembling the case in Candida albicans Although a small number of cells containing multiple nuclei appear in a short time after FLC treatment, we provide evidence that the heteroresistant colonies in the presence of FLC arise from uninucleate cells without involving multinuclear/multimeric stages. We found that fidelity of chromosome segregation in mitosis plays an important role in regulation of FLC heteroresistance frequency in C. neoformans Although FLC-resistant colonies occurred at a very low frequency, we were able to modulate the frequency of heteroresistance by overexpressing SMC1, which encodes a protein containing an SMC domain in chromosome segregation. Using time-lapse microscopy, we captured the entire process of colony formation from a single cell in the presence of FLC. All the multinucleated cells formed within a few hours of FLC exposure failed to multiply after a few cell divisions, and the cells able to proliferate to form colonies were all uninucleate without exception. Furthermore, no nuclear fusion event or asymmetric survival between mother and daughter cells, a hallmark of chromosome nondisjunction in haploid organisms, was observed. Therefore, the mechanisms of aneuploidy formation in C. neoformans appear different from most common categories of aneuploid formation known for yeasts.IMPORTANCE The gold standard of cryptococcosis treatment consists of induction therapy with amphotericin B followed by lifelong maintenance therapy with fluconazole (FLC). However, prolonged exposure to FLC induces the emergence of clones heteroresistant to azoles. All the heteroresistant clones thus far analyzed have been shown to be aneuploids, but how the aneuploid is formed remains unclear. Aneuploidy in fungi and other eukaryotic cells is known to result most commonly from chromosome missegregation during cell division due to defects in any one of the multiple components and processes that are required for the formation of two genetically identical daughter cells. Although formation of multinucleated cells has been observed in cells exposed to FLC, evidence for the emergence of drug-resistant aneuploid populations directly from such cells has been lacking. We show the evidence that the aneuploid in fluconazole-heteroresistant clones of Cryptococcus neoformans is derived neither from multinucleated cells nor from chromosome missegregation.
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Ray A, Oliver TR, Halder P, Pal U, Sarkar S, Dutta S, Ghosh S. Risk of Down syndrome birth: Consanguineous marriage is associated with maternal meiosis-II nondisjunction at younger age and without any detectable recombination error. Am J Med Genet A 2018; 176:2342-2349. [PMID: 30240118 DOI: 10.1002/ajmg.a.40511] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 05/17/2018] [Accepted: 07/26/2018] [Indexed: 01/10/2023]
Abstract
Consanguineous marriage was examined as a risk factor for Down syndrome birth. We genotyped Down syndrome family trios using short tandem repeat markers on 21q-to interpret the parental and meiotic stage of origin of errors as well as to record recombination profile along long arm of chromosome 21. We then compared nonconsanguineous (N = 811) group with-the consanguineous (N =157) marriages. We report for the first time that consanguineous marriage is associated with an increased risk for nondisjunction of chromosome 21 in oocytes-during the second meiotic division. We observed the absence of recombination more frequently in younger mothers in nonconsanguineous meiosis I cases. This was in contrast to an equal distribution of nonrecombinant cases across the age categories in the meiosis I consanguineous group. Moreover, the non-consanguineous group exhibited preferential telomeric recombination in meiosis I error among younger women and centromeric recombination in meiosis II errors in older women. In contrast, the consanguineous group exhibited medially placed recombination events in both meiosis I and meiosis II nondisjunction errors. Additionally, we recorded reduced maternal age at conception in the-consanguineous group. These findings suggest novel risk factors associated that increase the risk of chromosome 21 nondisjunction in the families with consanguinity.
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Affiliation(s)
- Anirban Ray
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | | | - Pinku Halder
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Upamanyu Pal
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Sumantra Sarkar
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Supratim Dutta
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Sujay Ghosh
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
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12
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Elloway JM, Davies AK, Hayes JE, Doherty AT. From the Cover: Does the Assessment of Nondisjunction Provide a More Sensitive Assay for the Detection of Aneugens? Toxicol Sci 2018; 157:20-29. [PMID: 28087838 DOI: 10.1093/toxsci/kfx014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The detection of aneugenic chemicals is important due to the implications of aneuploidy for human health. Aneuploidy can result from chromosome loss or nondisjunction due to chromosome mis-segregation at anaphase. Frequently, aneugens are detected using the in vitro micronucleus assay (IVM), with either centromere or kinetochore labeling. However, this method does not consider nondisjunction, the suggested predominant mechanism of spindle poison induced aneugenicity in primary human lymphocytes. Therefore, the IVM may be relatively insensitive in detecting aneuploidy. To investigate whether chromosome distribution analysis, specifically of nondisjunction, using chromosome-specific centromeric probes provides a more sensitive assay for aneugen detection, six reference aneugens with differing modes of action were tested on human lymphoblastoid TK6 cells. The results show that chromosome loss is a substantial part of the process leading to aneuploidy in TK6 cells. This differs from previous studies on human lymphocytes where nondisjunction has been described as the major mechanism of aneugenicity. However, in the current study more cells and types of aneugenic damage were analyzed. Although compound specific effects on nondisjunction were identified, chromosome distribution analysis did not provide increased sensitivity for the detection of aneugens: For the six reference aneugens examined, chromosome loss was shown at the same concentrations or lower than nondisjunction, even when nondisjunction levels were comparatively high. Therefore, in TK6 cells methods that detect chromosome loss, eg, the IVM, provide a more sensitive technique for the detection of aneugens than the measurement of nondisjunction.
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Affiliation(s)
- Joanne M Elloway
- AstraZeneca, Innovative Medicines and Early Development, Drug Safety and Metabolism (Discovery Safety), Unit 310-Darwin Building, Cambridge, UK
| | - Alexandra K Davies
- AstraZeneca, Innovative Medicines and Early Development, Drug Safety and Metabolism (Discovery Safety), Unit 310-Darwin Building, Cambridge, UK
| | - Julie E Hayes
- AstraZeneca, Innovative Medicines and Early Development, Drug Safety and Metabolism (Discovery Safety), AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire, UK
| | - Ann T Doherty
- AstraZeneca, Innovative Medicines and Early Development, Drug Safety and Metabolism (Discovery Safety), Unit 310-Darwin Building, Cambridge, UK
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13
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Hatkevich T, Kohl KP, McMahan S, Hartmann MA, Williams AM, Sekelsky J. Bloom Syndrome Helicase Promotes Meiotic Crossover Patterning and Homolog Disjunction. Curr Biol 2016; 27:96-102. [PMID: 27989672 DOI: 10.1016/j.cub.2016.10.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 11/28/2022]
Abstract
In most sexually reproducing organisms, crossover formation between homologous chromosomes is necessary for proper chromosome disjunction during meiosis I. During meiotic recombination, a subset of programmed DNA double-strand breaks (DSBs) are repaired as crossovers, with the remainder becoming noncrossovers [1]. Whether a repair intermediate is designated to become a crossover is a highly regulated decision that integrates several crossover patterning processes, both along chromosome arms (interference and the centromere effect) and between chromosomes (crossover assurance) [2]. Because the mechanisms that generate crossover patterning have remained elusive for over a century, it has been difficult to assess the relationship between crossover patterning and meiotic chromosome behavior. We show here that meiotic crossover patterning is lost in Drosophila melanogaster mutants that lack the Bloom syndrome helicase. In the absence of interference and the centromere effect, crossovers are distributed more uniformly along chromosomes. Crossovers even occur on the small chromosome 4, which normally never has meiotic crossovers [3]. Regulated distribution of crossovers between chromosome pairs is also lost, resulting in an elevated frequency of homologs that do not receive a crossover, which in turn leads to elevated nondisjunction.
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Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Kathryn P Kohl
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Susan McMahan
- Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA
| | - Michaelyn A Hartmann
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Andrew M Williams
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA; Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA.
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Begum F, Chowdhury R, Cheung VG, Sherman SL, Feingold E. Genome-Wide Association Study of Meiotic Recombination Phenotypes. G3 (Bethesda) 2016; 6:3995-4007. [PMID: 27733454 DOI: 10.1534/g3.116.035766] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Meiotic recombination is an essential step in gametogenesis, and is one that also generates genetic diversity. Genome-wide association studies (GWAS) and molecular studies have identified genes that influence of human meiotic recombination. RNF212 is associated with total or average number of recombination events, and PRDM9 is associated with the locations of hotspots, or sequences where crossing over appears to cluster. In addition, a common inversion on chromosome 17 is strongly associated with recombination. Other genes have been identified by GWAS, but those results have not been replicated. In this study, using new datasets, we characterized additional recombination phenotypes to uncover novel candidates and further dissect the role of already known loci. We used three datasets totaling 1562 two-generation families, including 3108 parents with 4304 children. We estimated five different recombination phenotypes including two novel phenotypes (average recombination counts within recombination hotspots and outside of hotspots) using dense SNP array genotype data. We then performed gender-specific and combined-sex genome-wide association studies (GWAS) meta-analyses. We replicated associations for several previously reported recombination genes, including RNF212 and PRDM9. By looking specifically at recombination events outside of hotspots, we showed for the first time that PRDM9 has different effects in males and females. We identified several new candidate loci, particularly for recombination events outside of hotspots. These include regions near the genes SPINK6, EVC2, ARHGAP25, and DLGAP2. This study expands our understanding of human meiotic recombination by characterizing additional features that vary across individuals, and identifying regulatory variants influencing the numbers and locations of recombination events.
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Clark FE, Conte MA, Ferreira-Bravo IA, Poletto AB, Martins C, Kocher TD. Dynamic Sequence Evolution of a Sex-Associated B Chromosome in Lake Malawi Cichlid Fish. J Hered 2016; 108:53-62. [PMID: 27630131 DOI: 10.1093/jhered/esw059] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 08/26/2016] [Indexed: 12/16/2022] Open
Abstract
B chromosomes are extra chromosomes found in many species of plants, animals, and fungi. B chromosomes often manipulate common cellular processes to increase their frequency, sometimes to the detriment of organismal fitness. Here, we characterize B chromosomes in several species of Lake Malawi cichlid fish. Whole genome sequencing of Metriaclima zebra "Boadzulu" individuals revealed blocks of sequence with unusually high sequence coverage, indicative of increased copy number of those sequences. These regions of high sequence coverage were found only in females. SNPs unique to the high copy number sequences permitted the design of specific amplification primers. These primers amplified fragments only in Metriaclima lombardoi individuals that carried a cytologically identified B chromosome (B-carriers), indicating these extra copies are located on the B chromosome. These same primers were used to identify B-carrying individuals in additional species from Lake Malawi. Across 7 species, a total of 43 B-carriers were identified among 323 females. B-carriers were exclusively female; no B chromosomes were observed in the 317 males surveyed from these species. Quantitative analysis of the copy number variation of B-specific sequence blocks suggests that B-carriers possess a single B chromosome, consistent with previous karyotyping of M. lombardoi A single B chromosome in B-carriers is consistent with 2 potential drive mechanisms: one involving nondisjunction and preferential segregation in a mitotic division prior to the germ-line, and the other involving preferential segregation during meiosis I.
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Affiliation(s)
- Frances E Clark
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins)
| | - Matthew A Conte
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins)
| | - Irani A Ferreira-Bravo
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins)
| | - Andreia B Poletto
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins)
| | - Cesar Martins
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins)
| | - Thomas D Kocher
- From the Department of Biology, University of Maryland, College Park, Maryland 20742 (Clark, Conte, and Kocher); Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 (Ferreira-Bravo); and Departamento de Morfologia, Instituto de Biociências, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil (Poletto and Martins).
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16
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Giauque CC, Bickel SE. Heterochromatin-Associated Proteins HP1a and Piwi Collaborate to Maintain the Association of Achiasmate Homologs in Drosophila Oocytes. Genetics 2016; 203:173-89. [PMID: 26984058 DOI: 10.1534/genetics.115.186460] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/11/2016] [Indexed: 12/21/2022] Open
Abstract
Accurate segregation of homologous chromosomes during meiosis depends on their ability to remain physically connected throughout prophase I. For homologs that achieve a crossover, sister chromatid cohesion distal to the chiasma keeps them attached until anaphase I. However, in Drosophila melanogaster wild-type oocytes, chromosome 4 never recombines, and the X chromosome fails to cross over in 6-10% of oocytes. Proper segregation of these achiasmate homologs relies on their pericentric heterochromatin-mediated association, but the mechanism(s) underlying this attachment remains poorly understood. Using an inducible RNA interference (RNAi) strategy combined with fluorescence in situ hybridization (FISH) to monitor centromere proximal association of the achiasmate FM7a/X homolog pair, we asked whether specific heterochromatin-associated proteins are required for the association and proper segregation of achiasmate homologs in Drosophila oocytes. When we knock down HP1a, H3K9 methytransferases, or the HP1a binding partner Piwi during mid-prophase, we observe significant disruption of pericentric heterochromatin-mediated association of FM7a/X homologs. Furthermore, for both HP1a and Piwi knockdown oocytes, transgenic coexpression of the corresponding wild-type protein is able to rescue RNAi-induced defects, but expression of a mutant protein with a single amino acid change that disrupts the HP1a-Piwi interaction is unable to do so. We show that Piwi is stably bound to numerous sites along the meiotic chromosomes, including centromere proximal regions. In addition, reduction of HP1a or Piwi during meiotic prophase induces a significant increase in FM7a/X segregation errors. We present a speculative model outlining how HP1a and Piwi could collaborate to keep achiasmate chromosomes associated in a homology-dependent manner.
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Abstract
Errors segregating homologous chromosomes during meiosis result in aneuploid gametes and are the largest contributing factor to birth defects and spontaneous abortions in humans. Saccharomyces cerevisiae has long served as a model organism for studying the gene network supporting normal chromosome segregation. Measuring homolog nondisjunction frequencies is laborious, and involves dissecting thousands of tetrads to detect missegregation of individually marked chromosomes. Here we describe a computational method (TetFit) to estimate the relative contributions of meiosis I nondisjunction and random-spore death to spore inviability in wild type and mutant strains. These values are based on finding the best-fit distribution of 4, 3, 2, 1, and 0 viable-spore tetrads to an observed distribution. Using TetFit, we found that meiosis I nondisjunction is an intrinsic component of spore inviability in wild-type strains. We show proof-of-principle that the calculated average meiosis I nondisjunction frequency determined by TetFit closely matches empirically determined values in mutant strains. Using these published data sets, TetFit uncovered two classes of mutants: Class A mutants skew toward increased nondisjunction death, and include those with known defects in establishing pairing, recombination, and/or synapsis of homologous chromosomes. Class B mutants skew toward random spore death, and include those with defects in sister-chromatid cohesion and centromere function. Epistasis analysis using TetFit is facilitated by the low numbers of tetrads (as few as 200) required to compare the contributions to spore death in different mutant backgrounds. TetFit analysis does not require any special strain construction, and can be applied to previously observed tetrad distributions.
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El-Gilany AH, Yahia S, Shoker M, El-Dahtory F. Cytogenetic and comorbidity profile of Down syndrome in Mansoura University Children's Hospital, Egypt. Indian J Hum Genet 2012; 17:157-63. [PMID: 22345986 PMCID: PMC3276983 DOI: 10.4103/0971-6866.92092] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND: Down syndrome (DS) is the most common chromosomal disorder. It has three chromosomal patterns. AIM: To determine the cytogenetic and comorbidity profiles of DS in the Genetic Unit of Mansoura University Children's Hospital, Mansoura, Egypt. MATERIALS AND METHODS: A retrospective analysis was performed on the case records of 712 cytogenetically diagnosed cases of DS at the Genetic Unit of Mansoura University Children's Hospital, Egypt, during a 10-year period. RESULTS: About 19% of the cases had one or more cardiac anomalies and about 8% were hypothyroid. Nondisjunction was the most common type of abnormality, followed by translocation and lastly mosaic: 96.1, 3.1, and 0.8%, respectively. Hypothyroidism was significantly more common in translocation and mosaic karyotypes than in the nondisjunction karyotypes. First and second birth orders were significantly higher in the translocation and mosaic groups than in the nondisjunction group. Mothers are significantly older at the index pregnancy in the nondisjunction group than in the other two groups. We compared our findings with those of previous studies. CONCLUSION: Knowing karyotype of DS will help in genetic counseling of the parents. Wide-scale national community-based survey with DS registry could help in estimating the size of the problem.
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Affiliation(s)
- Abdel-Hady El-Gilany
- Department of Public Health, Mansoura University Children's Hospital, Mansoura, Egypt
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Cyril C, Rai P, Chandra N, Gopinath PM, Satyamoorthy K. MTHFR Gene variants C677T, A1298C and association with Down syndrome: A Case-control study from South India. Indian J Hum Genet 2011; 15:60-4. [PMID: 20680153 PMCID: PMC2910950 DOI: 10.4103/0971-6866.55217] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms and low folate levels are associated with inhibition of DNA methyltransferase and consequently DNA hypomethylation. The expanding spectrum of common conditions linked with MTHFR polymorphisms includes certain adverse birth outcome, pregnancy complications, cancers, adult cardiovascular diseases and psychiatric disorders, with several of these associations remaining still controversial. Trisomy 21 or Down syndrome (DS) is the most common genetic cause of mental retardation. It stems predominantly from the failure of chromosome 21 to segregate normally during meiosis. Despite substantial research, the molecular mechanisms underlying non-disjunction leading to trisomy 21 are poorly understood. MATERIALS AND METHODS Two common variants C677T and A1298C of the MTHFR gene were screened in 36 parents with DS children and 60 healthy couples from Tamil Nadu and Karnataka. The MTHFR genotypes were studied by RFLP analysis of PCR-amplified products and confirmed by sequencing. RESULTS The CT genotype was seen in three each (8.3%) of case mothers and fathers. One case father showed TT genotype. All the control individuals exhibited the wild type CC genotype. A similar frequency for the uncommon allele C of the second polymorphism was recorded in case mothers (0.35) and fathers (0.37) in comparison with the control mothers (0.39) and fathers (0.37). CONCLUSION This first report on MTHFR C677T and A1298C polymorphisms in trisomy 21 parents from south Indian population revealed that MTHFR 677CT polymorphism was associated with a risk for Down syndrome.
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Affiliation(s)
- Cyrus Cyril
- Department of Genetics, Dr. ALMPGIBMS, University of Madras, Taramani, Chennai - 600 113, India
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20
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Mendes CC, Biselli JM, Zampieri BL, Goloni-Bertollo EM, Eberlin MN, Haddad R, Riccio MF, Vannucchi H, Carvalho VM, Pavarino-Bertelli EC. 19-base pair deletion polymorphism of the dihydrofolate reductase (DHFR) gene: maternal risk of Down syndrome and folate metabolism. SAO PAULO MED J 2010; 128:215-8. [PMID: 21120433 PMCID: PMC10938985 DOI: 10.1590/s1516-31802010000400008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 02/08/2010] [Accepted: 06/21/2010] [Indexed: 12/22/2022] Open
Abstract
CONTEXT AND OBJECTIVE Polymorphisms in genes involved in folate metabolism may modulate the maternal risk of Down syndrome (DS). This study evaluated the influence of a 19-base pair (bp) deletion polymorphism in intron-1 of the dihydrofolate reductase (DHFR) gene on the maternal risk of DS, and investigated the association between this polymorphism and variations in the concentrations of serum folate and plasma homocysteine (Hcy) and plasma methylmalonic acid (MMA). DESIGN AND SETTING Analytical cross-sectional study carried out at Faculdade de Medicina de São José do Rio Preto (Famerp). METHODS 105 mothers of individuals with free trisomy of chromosome 21, and 184 control mothers were evaluated. Molecular analysis on the polymorphism was performed using the polymerase chain reaction (PCR) through differences in the sizes of fragments. Folate was quantified by means of chemiluminescence, and Hcy and MMA by means of liquid chromatography and sequential mass spectrometry. RESULTS There was no difference between the groups in relation to allele and genotype frequencies (P = 0.44; P = 0.69, respectively). The folate, Hcy and MMA concentrations did not differ significantly between the groups, in relation to genotypes (P > 0.05). CONCLUSIONS The 19-bp deletion polymorphism of DHFR gene was not a maternal risk factor for DS and was not related to variations in the concentrations of serum folate and plasma Hcy and MMA in the study population.
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Affiliation(s)
- Cristiani Cortez Mendes
- Department of Molecular Biology, Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, São Paulo, Brazil
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Peddibhotla S, Lam MH, Gonzalez-Rimbau M, Rosen JM. The DNA-damage effector checkpoint kinase 1 is essential for chromosome segregation and cytokinesis. Proc Natl Acad Sci U S A 2009; 106:5159-64. [PMID: 19289837 PMCID: PMC2663996 DOI: 10.1073/pnas.0806671106] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Indexed: 11/18/2022] Open
Abstract
Defective genome maintenance mechanisms, involving DNA repair and cell-cycle checkpoint pathways, initiate genetic instability in many sporadic and hereditary cancers. The DNA damage effector Checkpoint kinase 1 (Chk1) is a critical component of DNA replication, intra-S phase, and G(2)/M phase checkpoints and a recently reported mitotic spindle-assembly checkpoint. Here, we report for the first time that haploinsufficiency of Chk1 in mice resulted in multiple mitotic defects and enhanced binucleation. We observed that Aurora B, a critical cytokinetic regulator and a recently identified Chk1 substrate, was mislocalized in mitotic Chk1(+/-) mammary epithelia. Chk1 also exhibited distinct mitotic localization patterns and was active during unperturbed mitosis and cytokinesis in mammalian cells. Active Chk1 expression was not dependent on treatment with spindle poisons such as colcemid during mitosis and cytokinesis. Furthermore, two different complementary approaches demonstrated that abrogation of Chk1 in mitotic mammalian cells resulted in cytokinetic regression and binucleation, increased chromosome lagging and/or nondisjunction, and abnormal localization of Aurora B at late mitotic structures. Thus, Chk1 is a multifunctional kinase that serves as a nexus between the DNA damage response and the mitotic exit pathways during cell-cycle progression to prevent genomic instability and cancer.
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Affiliation(s)
- Sirisha Peddibhotla
- Interdepartmental Program in Cell and Molecular Biology and
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Michael H. Lam
- Interdepartmental Program in Cell and Molecular Biology and
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Maria Gonzalez-Rimbau
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Jeffrey M. Rosen
- Interdepartmental Program in Cell and Molecular Biology and
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030
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Asada H, Sueoka K, Hashiba T, Kuroshima M, Kobayashi N, Yoshimura Y. The effects of age and abnormal sperm count on the nondisjunction of spermatozoa. J Assist Reprod Genet 2000; 17:51-9. [PMID: 10754784 PMCID: PMC3455190 DOI: 10.1023/a:1009454114973] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE The effect of paternal age on the nondisjunction of sex chromosomes is controversial. Also, the prevalence of chromosomal anomalies in infertile patients is controversial, it has been reported that the sex chromosomal aneuploidy rate following treatment with intracytoplasmic sperm injection (ICSI) is higher than in naturally conceived pregnancies. We investigated the influence of paternal age and oligozoospermia on the nondisjunction of spermatozoa. METHODS We determined the rate of aneuploidy for gonosomes and autosomes, using two-color fluorescence in situ hybridization (FISH) of the X and Y chromosomes and chromosomes 12 and 18 in 10 donors under 25 years of age who had a normal sperm count (> or = 20 x 10(6)/ml), 10 donors over the age of 39 years with idiopathic infertility and normozoospermia (> or = 20 x 10(6)/ml), and 5 oligozoospermic donors (< 20 x 10(6)/ml). RESULTS There was no obvious relationship between increasing age and autosomal disomy (disomy 12 and disomy 18). Neither autosomal disomy nor diploidy was increased in any group. The frequency of X-, Y-, XX-, and YY-bearing sperm did not differ significantly among groups, but the frequency of XY-bearing sperm was significantly higher in the older infertile group than in the control donors. CONCLUSIONS The incidence of nondisjunction of paternal sex chromosome in meiosis I was higher in older men with idiopathic infertility. The present results suggest that the risk of producing XXY fetuses is higher among men > 39 years of age with idiopathic infertility.
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Affiliation(s)
- H Asada
- Department of Obstetrics & Gynecology, Keio University School of Medicine, Tokyo, Japan
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