Minichromosome Analysis of Chromosome Pairing, Disjunction, and Sister Chromatid Cohesion in Maize

Han, Fangpu; Gao, Zhi; Yu, Weichang; Birchler, James A.

doi:10.1105/tpc.107.055905

Cited by 65 publications

(60 citation statements)

References 52 publications

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“…Using a translocation of the B chromosome and the short arm of chromosome 9 that has a foldback duplication , recombination between it and a misdivision derivative also carrying 9S will pit a large and small centromere against each other in anaphase I or allow them to assort to the same pole (Figure 1). The TB-9Sb-Dp9 chromosome is a translocation containing the supernumerary B chromosome centromere with two short arms of maize chromosome 9 but reversed in order (Zheng et al, 1999;Han et al, 2007b). Misdivision derivatives were also derived ultimately from TB-9Sb and have been classified as to their chromosomal constitution Birchler, 1996, 1998).…”

Section: Inactivation Of Centromeres From a Tug Of Warmentioning

confidence: 99%

Reactivation of an Inactive Centromere Reveals Epigenetic and Structural Components for Centromere Specification in Maize

2009

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Stable maize (Zea mays) chromosomes were recovered from an unstable dicentric containing large and small versions of the B chromosome centromere. In the stable chromosome, the smaller centromere had become inactivated. This inactive centromere can be inherited from one generation to the next attached to the active version and loses all known cytological and molecular properties of active centromeres. When separated from the active centromere by intrachromosomal recombination, the inactive centromere can be reactivated. The reactivated centromere regains the molecular attributes of activity in anaphase I of meiosis. When two copies of the dicentric chromosome with one active and one inactive centromere are present, homologous chromosome pairing reduces the frequency of intrachromosomal recombination and thus decreases, but does not eliminate, the reactivation of inactive centromeres. These findings indicate an epigenetic component to centromere specification in that centromere inactivation can be directed by joining two centromeres in opposition. These findings also indicate a structural aspect to centromere specification revealed by the gain of activity at the site of the previously inactive sequences.

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Section: Inactivation Of Centromeres From a Tug Of Warmentioning

confidence: 99%

Reactivation of an Inactive Centromere Reveals Epigenetic and Structural Components for Centromere Specification in Maize

2009

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“…4a-c). This mini-B chromosome was derived from the complex A-B translocation chromosome B-9-Dp9 (Han et al 2007) and has undergone extensive rearrangements from breakage-fusion-bridge (BFB) cycles. The size of the mini-B chromosome was reduced to ;7% (7.43% 6 1.47%, n = 6) of the normal B chromosome, but it retained a fully functioning centromere ( Fig.…”

Section: Development Of a Dna Fiber-based Technique For Mapping Cytosmentioning

confidence: 99%

“…A maize line containing the mini-B chromosome was derived from breakage-fusionbridge (BFB) cycles of the B-9-Dp9 translocation chromosome (Han et al 2007). The maize line containing an inactivated B centromere was developed at the University of Missouri.…”

Section: Plant Materials and Chromosome Preparationsmentioning

confidence: 99%

Distinct DNA methylation patterns associated with active and inactive centromeres of the maize B chromosome

Koo¹,

Han²,

Birchler³

et al. 2011

Genome Res.

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Centromeres are determined by poorly understood epigenetic mechanisms. Centromeres can be activated or inactivated without changing the underlying DNA sequences. However, virtually nothing is known about the epigenetic transition of a centromere from an active to an inactive state because of the lack of examples of the same centromere exhibiting alternative forms and being distinguishable from other centromeres. The centromere of the supernumerary B chromosome of maize provides such an opportunity because its functional core can be cytologically tracked, and an inactive version of the centromere is available. We developed a DNA fiber-based technique that can be used to assess the levels of cytosine methylation associated with repetitive DNA sequences. We report that DNA sequences in the normal B centromere exhibit hypomethylation. This methylation pattern is not affected by the genetic background or structural rearrangement of the B chromosome, but is slightly changed when the B chromosome is transferred to oat as an addition chromosome. In contrast, an inactive version of this same centromere exhibits hypermethylation, indicating that the inactive centromere was modified into a different epigenetic state at the DNA level. [Supplemental material is available for this article.]The functional centromere is specified by the presence of a special histone H3 variant, known as CENH3 in plants. The establishment and maintenance of centromeres are not defined by the underlying DNA sequences but, rather, are determined by epigenetic mechanisms (Allshire and Karpen 2008). Centromeres can be inactivated (Earnshaw and Migeon 1985;Sullivan and Schwartz 1995;Han et al. 2006;Zhang et al. 2010), or they can also be activated as ''neocentromeres'' from non-centromeric regions (Williams et al. 1998;Nasuda et al. 2005;Marshall et al. 2008;Gong et al. 2009;Topp et al. 2009) or re-activated from a previously inactivated centromere (Han et al. 2009). Most strikingly, human neocentromeres were established at numerous locations associated with most chromosomes and are as fully functional as normal centromeres (Marshall et al. 2008). Despite the extensive and compelling evidence for the epigenetic regulation of centromere establishment and maintenance, there has been limited information as to what epigenetic modifications are important or specific to centromeric chromatin. The slow progress of this important research subject is largely due to the fact that centromeres in most multicellular eukaryotes are composed of megabase-sized arrays of satellite repeats (Henikoff et al. 2001;Jiang et al. 2003), which prevent DNA sequence-based fine mapping of epigenetic marks, such as DNA methylation and histone modifications.Using an immunofluorescence assay on highly stretched meiotic pachytene chromosomes, we recently demonstrated a characteristic hypomethylation pattern associated with the satellite repeats in CENH3-associated chromatin (CEN chromatin) in both Arabidopsis thaliana and maize (Zea mays). In contrast, the same satellite repeats lo...

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“…189 In maize, Shugoshin homolog ZMSgo1 is required for maintenance of centromeric cohesin during meiosis but it does not have mitotic functions. 194 Evidence of Shogoshin as a protector of centromeric cohesin was also reported in mammalian meiosis. In mouse oocytes, both Shogoshin proteins are centromeric proteins.…”

Section: Two-step Releases Of Cohesionmentioning

confidence: 99%

Molecular insights into mechanisms regulating faithful chromosome separation in female meiosis

Yin

Sun²,

Schatten³

et al. 2008

Cell Cycle

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The faithful segregation of chromosomes into daughter cells in meiosis is crucial to produce healthy progeny. In gametogenesis, two consecutive rounds of chromosome separation occur with only one round of DNA replication, and the chromosome number is reduced to half to produce haploid gametes. Here, we discuss the molecular mechanisms underlying faithful chromosome separation in meiosis from three aspects: spindle checkpoint, two-step releases of cohesion, and the specific space-time protection of cohesin.

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Minichromosome Analysis of Chromosome Pairing, Disjunction, and Sister Chromatid Cohesion in Maize

Cited by 65 publications

References 52 publications

Reactivation of an Inactive Centromere Reveals Epigenetic and Structural Components for Centromere Specification in Maize

Reactivation of an Inactive Centromere Reveals Epigenetic and Structural Components for Centromere Specification in Maize

Distinct DNA methylation patterns associated with active and inactive centromeres of the maize B chromosome

Molecular insights into mechanisms regulating faithful chromosome separation in female meiosis

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