The Triticum-Aegilops complex groups demonstrated high cross-affinity with each other to overcome the barriers of distant hybridization(Loureiro et al.,2023).Distant hybridization involves two distinct yet closely rel...The Triticum-Aegilops complex groups demonstrated high cross-affinity with each other to overcome the barriers of distant hybridization(Loureiro et al.,2023).Distant hybridization involves two distinct yet closely related events:hybridization and genome doubling.Previous studies have indicated that bursts of transposable elements(TEs)can occur as a consequence or concomitant to hybridization or genome duplication(Parisod et al.,2010).This raises an important scientific question regarding how the TEs-rich centromere region copes with genomic shock(McClintock,1984).The Triticum-Aegilops species complexes,particularly in the F1,So,and subsequent early generations resulting from successive selfcrossing,offer an opportunity to investigate whether the centromere environment undergoes reconstruction and the associated mechanisms that maintain genomic stability.展开更多
The centromere is a defining region that mediates chromosome attachment to kinetochore microtubules and proper segregation of the sister chromatids. Intriguingly, satellite DNA and centromeric retrotransposon as major...The centromere is a defining region that mediates chromosome attachment to kinetochore microtubules and proper segregation of the sister chromatids. Intriguingly, satellite DNA and centromeric retrotransposon as major DNA constituents of centromere showed baffling diversification and species-specific. However, the key kinetochore proteins are conserved in both plants and animals, particularly the centromere-specific histone H3-1ike protein （CENH3） in all functional centromeres. Recent studies have highlighted the importance of epigenetic mechanisms in the establishment and maintenance of centromere identity. Here, we review the progress and compendium of research on plant centromere in the light of recent data.展开更多
R-loops play various roles in many physiological processes,however,their role in meiotic division remains largely unknown.Here we show that R-loops and their regulator RNase H1 are present at centromeres during oocyte...R-loops play various roles in many physiological processes,however,their role in meiotic division remains largely unknown.Here we show that R-loops and their regulator RNase H1 are present at centromeres during oocyte meiotic divisions.Proper centromeric R-loops are essential to ensure chromosome alignment in oocytes during metaphase I(MI).Remarkably,both Rnaseh1 knockout and overexpression in oocytes lead to severe spindle assembly defects and chromosome misalignment due to dysregulation of R-loops at centromeres.Furthermore,we find that replication protein A(RPA)is recruited to centromeric R-loops,facilitating the deposition of ataxia telangiectasia-mutated and Rad3-related(ATR)kinase at centromeres by interacting with the ATR-interaction protein(ATRIP).The ATR kinase deposition triggers the activity of CHK1,stimulating the phosphorylation of Aurora B to finally promote proper spindle assembly and chromosome alignment at the equatorial plate.Most importantly,the application of ATR,CHK1,and Aurora B inhibitors could efficiently rescue the defects in spindle assembly and chromosome alignment due to RNase H1 deficiency in oocytes.Overall,our findings uncover a critical role of R-loops during mouse oocyte meiotic divisions,suggesting that dysregulation of R-loops may be associated with female infertility.Additionally,ATR,CHK1,and Aurora B inhibitors may potentially be used to treat some infertile patients.展开更多
Centromere positioning and organization are crucial for genome evolution;however,research on centro-mere biology is largely influenced by the quality of available genome assemblies.Here,we combined Oxford Nanopore and...Centromere positioning and organization are crucial for genome evolution;however,research on centro-mere biology is largely influenced by the quality of available genome assemblies.Here,we combined Oxford Nanopore and Pacific Biosciences technologies to de novo assemble two high-quality reference genomes for Gossypium hirsutum(TM-1)and Gossypium barbadense(3-79).Compared with previously published reference genomes,our assemblies show substantial improvements,with the contig N50 improved by 4.6-fold and 5.6-fold,respectively,and thus represent the most complete cotton genomes to date.These high-quality reference genomes enable us to characterize 14 and 5 complete centromeric regions for G.hirsutum and G.barbadense,respectively.Our data revealed that the centromeres of allotetraploid cotton are occupied by members of the centromeric repeat for maize(CRM)and Tekay long terminal repeat families,and the CRM family reshapes the centromere structure of the At subgenome after polyploidization.These two intertwined families have driven the convergent evolution of centromeres between the two subgenomes,ensuring centromere function and genome stability.In addition,the reposi-tioning and high sequence divergence of centromeres between G.hirsutum and G.barbadense have contributed to speciation and centromere diversity.This study sheds light on centromere evolution in a sig-nificant crop and provides an alternative approach for exploring the evolution of polyploid plants.展开更多
Rice(Oryza sativa)is a significant crop worldwide with a genome shaped by various evolutionary factors.Rice centromeres are crucial for chromosome segregation,and contain some unreported genes.Due to the diverse and c...Rice(Oryza sativa)is a significant crop worldwide with a genome shaped by various evolutionary factors.Rice centromeres are crucial for chromosome segregation,and contain some unreported genes.Due to the diverse and complex centromere region,a comprehensive understanding of rice centromere structure and function at the population level is needed.We constructed a high-quality centromere map based on the rice super pangenome consisting of a 251-accession panel comprising both cultivated and wild species of Asian and African rice.We showed that rice centromeres have diverse satellite repeat CentO,which vary across chromosomes and subpopulations,reflecting their distinct evolutionary patterns.We also revealed that long terminal repeats(LTRs),especially young Gypsy-type LTRs,are abundant in the peripheral CentO-enriched regions and drive rice centromere expansion and evolution.Furthermore,high-quality genome assembly and complete telomere-to-telomere(T2T)reference genome enable us to obtain more centromeric genome information despite mapping and cloning of centromere genes being challenging.We investigated the association between structural variations and gene expression in the rice centromere.A centromere gene,OsMAB,which positively regulates rice tiller number,was further confirmed by expression quantitative trait loci,haplotype analysis and clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein9 methods.By revealing the new insights into the evolutionary patterns and biological roles of rice centromeres,our finding will facilitate future research on centromere biology and crop improvement.展开更多
Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting divers...Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting diverse sizes and compositions across species.The functional significance of rye centromeric DNA sequences,particularly in centromere identity,remains unclear.In this study,we comprehensively characterized the sequence composition and organization of rye centromeres.Our findings revealed that these centromeres are primarily composed of long terminal repeat retrotransposons(LTR-RTs)and interspersed minisatellites.We systematically classified LTR-RTs into five categories,highlighting the prevalence of younger CRS1,CRS2,and CRS3 of CRSs(centromeric retrotransposons of Secale cereale)were primarily located in the core centromeres and exhibited a higher association with CENH3 nucleosomes.The minisatellites,mainly derived from retrotransposons,along with CRSs,played a pivotal role in establishing functional centromeres in rye.Additionally,we observed the formation of R-loops at specific regions of CRS1,CRS2,and CRS3,with both rye pericentromeres and centromeres exhibiting enrichment in R-loops.Notably,these R-loops selectively formed at binding regions of the CENH3 nucleosome in rye centromeres,suggesting a potential role in mediating the precise loading of CENH3 to centromeres and contributing to centromere specification.Our work provides insights into the DNA sequence composition,distribution,and potential function of R-loops in rye centromeres.This knowledge contributes valuable information to understanding the genetics and epigenetics of rye centromeres,offering implications for the development of synthetic centromeres in future plant modifications and beyond.展开更多
Increasing number of structural variations(SVs)have been identified as causative mutations for diverse agronomic traits.However,the systematic exploration of SVs quantity,distribution,and contribution in wheat was lac...Increasing number of structural variations(SVs)have been identified as causative mutations for diverse agronomic traits.However,the systematic exploration of SVs quantity,distribution,and contribution in wheat was lacking.Here,we report high-quality gene-based and SV-based pangenomes comprising 22 hexaploid wheat assemblies showing a wide range of chromosome size,gene number,and TE component,which indicates their representativeness of wheat genetic diversity.Pan-gene analyses uncover 140,261 distinct gene families,of which only 23.2%are shared in all accessions.Moreover,we build a∼16.15 Gb graph pangenome containing 695,897 bubbles,intersecting 5132 genes and 230,307 cis-regulatory regions.Pairwise genome comparisons identify∼1,978,221 non-redundant SVs and 497 SV hotspots.Notably,the density of bubbles as well as SVs show remarkable aggregation in centromeres,which probably play an important role in chromosome plasticity and stability.As for functional SVs exploration,we identify 2769 SVs with absolute relative frequency differences exceeding 0.7 between spring and winter growth habit groups.Additionally,several reported functional genes in wheat display complex structural graphs,for example,PPD-A1,VRT-A2,and TaNAAT2-A.These findings deepen our understanding of wheat genetic diversity,providing valuable graphical pangenome and variation resources to improve the efficiency of genome-wide association mapping in wheat.展开更多
Background Chickens and ducks are vital sources of animal protein for humans.Recent pangenome studies suggest that a single genome is insufficient to represent the genetic information of a species,highlighting the nee...Background Chickens and ducks are vital sources of animal protein for humans.Recent pangenome studies suggest that a single genome is insufficient to represent the genetic information of a species,highlighting the need for more comprehensive genomes.The bird genome has more than tens of microchromosomes,but comparative genomics,annotations,and the discovery of variations are hindered by inadequate telomere-to-telomere level assemblies.We aim to complete the chicken and duck genomes,recover missing genes,and reveal common and unique chromosomal features between birds.Results The near telomere-to-telomere genomes of Silkie Gallus gallus and Mallard Anas platyrhynchos were successfully assembled via multiple high-coverage complementary technologies,with quality values of 36.65 and 44.17 for Silkie and Mallard,respectively;and BUSCO scores of 96.55%and 96.97%for Silkie and Mallard,respectively;the mapping rates reached over 99.52%for both assembled genomes,these evaluation results ensured high completeness and accuracy.We successfully annotated 20,253 and 19,621 protein-coding genes for Silkie and Mallard,respectively,and assembled gap-free sex chromosomes in Mallard for the first time.Comparative analysis revealed that microchromosomes differ from macrochromosomes in terms of GC content,repetitive sequence abundance,gene density,and levels of 5mC methylation.Different types of arrangements of centromeric repeat sequence centromeres exist in both Silkie and the Mallard genomes,with Mallard centromeres being invaded by CR1.The highly heterochromatic W chromosome,which serves as a refuge for ERVs,contains disproportionately long ERVs.Both Silkie and the Mallard genomes presented relatively high 5mC methylation levels on sex chromosomes and microchromosomes,and the telomeres and centromeres presented significantly higher 5mC methylation levels than the whole genome.Finally,we recovered 325 missing genes via our new genomes and annotated TNFA in Mallard for the first time,revealing conserved protein structures and tissue-specific expression.Conclusions The near telomere-to-telomere assemblies in Mallard and Silkie,with the first gap-free sex chromosomes in ducks,significantly enhanced our understanding of genetic structures in birds,specifically highlighting the distinctive chromosome features between the chicken and duck genomes.This foundational work also provides a series of newly identified missing genes for further investigation.展开更多
BACKGROUND Centromere protein A(CENPA)exhibits an increased expression level in primary human rectal cancer tissues,but its role has not been investigated.AIM To clarify the specific role and mechanism of CENPA in rec...BACKGROUND Centromere protein A(CENPA)exhibits an increased expression level in primary human rectal cancer tissues,but its role has not been investigated.AIM To clarify the specific role and mechanism of CENPA in rectal cancer progression.METHODS CENPA protein expression in rectal cancer tissues and cell lines were detected.CENPA was overexpressed and knocked down in SW837 and SW480 cells,and proliferation,invasion,apoptosis and epithelial-mesenchymal transition(EMT)marker protein levels were examined.O6-methylguanine DNA methyltransferase(MGMT)promoter methylation was assessed with methylation-specific poly-merase chain reaction.Co-immunoprecipitation assay verified the interaction between MGMT and protein tyrosine phosphatase nonreceptor type 4(PTPN4).SW837 cells with CENPA knockdown were injected subcutaneously into mice,and tumor growth was examined.RESULTS CENPA was upregulated in rectal cancer tissues and cell lines.CENPA overex-pression promoted proliferation,invasion and EMT,and inhibited apoptosis in rectal cancer cells.Whereas CENPA knockdown showed the opposite results.Moreover,CENPA inhibited MGMT expression by promoting DNA methyltrans-ferase 1-mediated MGMT promoter methylation.MGMT knockdown abolished the CENPA knockdown-mediated inhibition of rectal cancer cell progression.MGMT increased PTPN4 protein stability by inhibiting PTPN4 ubiquitination degradation via competing with ubiquitin-conjugating enzyme E2O for interacting with PTPN4.PTPN4 knockdown abolished the inhibitory effects of MGMT overexpression on rectal cancer cell progression.Moreover,CENPA knockdown inhibited xenograft tumor growth in vivo.CONCLUSION CENPA knockdown inhibited rectal cancer cell growth and attenuated xenograft tumor growth through regulating the MGMT/PTPN4 axis.展开更多
The centromere is a highly organized structure mainly composed of repeat sequences,which make this region extremely difficult for sequencing and other analyses.It plays a conserved role in equal division of chromosome...The centromere is a highly organized structure mainly composed of repeat sequences,which make this region extremely difficult for sequencing and other analyses.It plays a conserved role in equal division of chromosomes into daughter cells in both mitosis and meiosis.However,centromere sequences show notable plasticity.In a dicentric chromosome,one of the centromeres can become inactivated with the underlying DNA unchanged.Furthermore,formerly inactive centromeres can regain activity under certain conditions.In addition,neocentromeres without centromeric repeats have been found in a wide spectrum of species.This evidence indicates that epigenetic mechanisms together with centromeric sequences are associated with centromere specification.展开更多
Dear Editor,Legumes,including soybean and alfalfa,are vital agricultural crops worldwide,providing high-quality protein and oil sources for humans and animals.In addition,legumes also provide nitrogen for soil improve...Dear Editor,Legumes,including soybean and alfalfa,are vital agricultural crops worldwide,providing high-quality protein and oil sources for humans and animals.In addition,legumes also provide nitrogen for soil improvement,benefiting from their symbiotic associations with nitrogen-fixing bacteria.展开更多
Wheat-rye addition and substitution lines and their self progenies revealed variations in telomeric heterochromatin and centromeres, Furthermore, a mitotically unstable dicentric chromosome and stable multicentric chr...Wheat-rye addition and substitution lines and their self progenies revealed variations in telomeric heterochromatin and centromeres, Furthermore, a mitotically unstable dicentric chromosome and stable multicentric chromosomes were observed in the progeny of a Chinese Spring-lmperial rye 3R addition line. An unstable multicentric chromosome was found in the progeny of a 6R/6D substitution line. Drastic variation of terminal heterochromatin including movement and disappearance of terminal heterochromatin occurred in the progeny of wheat- rye addition line 3R, and the 5RS ditelosomic addition line. Highly stable minichromosomes were observed in the progeny ofa monosomic 4R addition line, a ditelosomic 5RS addition line and a 6R/6D substitution line. Minichromosomes, with and without the FISH signals for telomeric DNA （TTTAGGG）n, derived from a monosomic 4R addition line are stable and transmissible to the next generation. The results indicated that centromeres and terminal heterochromatin can be profoundly altered in wheat-rye hybrid derivatives.展开更多
Background:Stemness and chemoresistance contribute to cervical cancer recurrence and metastasis.In the current study,we determined the relevant players and role of N^(6)-methyladenine(m^(6)A)RNA methylation in cervica...Background:Stemness and chemoresistance contribute to cervical cancer recurrence and metastasis.In the current study,we determined the relevant players and role of N^(6)-methyladenine(m^(6)A)RNA methylation in cervical cancer progression.Methods:The roles of m^(6)A RNA methylation and centromere protein K(CENPK)in cervical cancer were analyzed using bioinformatics analysis.Methylated RNA immunoprecipitation was adopted to detect m^(6)A modification of CENPK mRNA.Human cervical cancer clinical samples,cell lines,and xenografts were used for analyzing gene expression and function.Immunofluorescence staining and the tumorsphere formation,clonogenic,MTT,and EdU assays were performed to determine cell stemness,chemoresistance,migration,invasion,and proliferation in HeLa and SiHa cells,respectively.Western blot analysis,co-immunoprecipitation,chromatin immunoprecipitation,and luciferase reporter,cycloheximide chase,and cell fractionation assays were performed to elucidate the underlying mechanism.Results:Bioinformatics analysis of public cancer datasets revealed firm links between m^(6)A modification patterns and cervical cancer prognosis,especially through ZC3H13-mediated m^(6)A modification of CENPK mRNA.CENPK expression was elevated in cervical cancer,associated with cancer recurrence,and independently predicts poor patient prognosis[hazard ratio=1.413,95%confidence interval=1.078−1.853,P=0.012].Silencing of CENPK prolonged the overall survival time of cervical cancer-bearing mice and improved the response of cervical cancer tumors to chemotherapy in vivo(P<0.001).We also showed that CENPK was directly bound to SOX6 and disrupted the interactions of CENPK withβ-catenin,which promotedβ-catenin expression and nuclear translocation,facilitated p53 ubiquitination,and led to activation of Wnt/β-catenin signaling,but suppression of the p53 pathway.This dysregulation ultimately enhanced the tumorigenic pathways required for cell stemness,DNA damage repair pathways necessary for cisplatin/carboplatin resistance,epithelial-mesenchymal transition involved in metastasis,and DNA replication that drove tumor cell proliferation.Conclusions:CENPK was shown to have an oncogenic role in cervical cancer and can thus serve as a prognostic indicator and novel target for cervical cancer treatment.展开更多
A thermo-insensitive pale green leaf mutant （pgl2） was isolated from T-DNA inserted transgenic lines of rice （Oryza sativa L. subsp, japonica cv. Nipponbare）. Genetic analysis indicated that the phenotype was caus...A thermo-insensitive pale green leaf mutant （pgl2） was isolated from T-DNA inserted transgenic lines of rice （Oryza sativa L. subsp, japonica cv. Nipponbare）. Genetic analysis indicated that the phenotype was caused by a recessive mutation in a single nuclear-encoded gene. To map the PGL2gene, an F2 population was constructed by crossing the mutant with Longtefu （Oryza sativa L. subsp, indica）. The PGL2 locus was roughly linked to SSR marker RM331 on chromosome 8. To finely map the gene, 14 new InDel markers were developed around the marker, and PGL2 was further mapped to a 2.37 Mb centromeric region. Analysis on chlorophyll contents of leaves showed that there was no obvious difference between the mutant and the wild type in total chlorophyll （Chl） content, while the ratio of Chl a / Chl b in the mutant was only about 1, which was distinctly lower than that in the wild type, suggesting that the PGL2 gene was related to the conversion between Chl a and Chl b. Moreover, the method of primer design around the centromeric region was discussed, which would provide insight into fine mapping of the functional genes in plant centromeres.展开更多
Plant centromeres are generally composed of tandem arrays of simple repeats that form a complex chromosome locus where the kinetochore forms and microtubules attach during mitosis and meiosis. Each chromosome has one ...Plant centromeres are generally composed of tandem arrays of simple repeats that form a complex chromosome locus where the kinetochore forms and microtubules attach during mitosis and meiosis. Each chromosome has one centromere region, which is essential for accurate division of the genetic material. Recently, chromosomes containing two centromere regions （called dicentric chromosomes） have been found in maize and wheat. Interestingly, some dicentric chromosomes are stable because only one centromere is active and the other one is inactivated. Because such arrays maintain their typical structure for both active and inactive centromeres, the specification of centromere activity has an epigenetic component independent of the DNA sequence. Under some circumstances, the inactive centromeres may recover centromere function, which is called centromere reactivation. Recent studies have highlighted the important changes, such as DNA methylation and histone modification, that occur during centromere inactivation and reactivation.展开更多
BACKGROUND Colorectal cancer(CRC)is one of the most common malignant tumors worldwide.The identification of novel diagnostic and prognostic biomarkers for CRC is a key research imperative.Immunohistochemical analysis ...BACKGROUND Colorectal cancer(CRC)is one of the most common malignant tumors worldwide.The identification of novel diagnostic and prognostic biomarkers for CRC is a key research imperative.Immunohistochemical analysis has revealed high expression of centromere protein K(CENPK)in CRC.However,the role of CENPK in the progression of CRC is not well characterized.AIM To evaluate the effects of knockdown of CENPK and overexpression of Cullin 4A(CUL4A)in RKO and HCT116 cells.METHODS Human colon cancer samples were collected and tested using a human gene expression chip.We identified CENPK as a potential oncogene for CRC based on bioinformatics analysis.In vitro experiments verified the function of this gene.We investigated the expression of CENPK in RKO and HCT116 cells using quantitative polymerase chain reaction(qPCR),western blot,and flow cytometry.The effect of short hairpin RNA(shRNA)virus-infected RKO cells on tumor growth was evaluated in vivo using quantitative analysis of fluorescence imaging.To evaluate the effects of knockdown of CENPK and overexpression of CUL4A in RKO and HCT116 cells,we performed a series of in vitro experiments,using qPCR,western blot,MTT assay,and flow cytometry.RESULTS We demonstrated overexpression of CENPK in human colon cancer samples.CENPK was an independent risk factor in patients with CRC.The downstream genes FBX32,CUL4A,and Yesassociated protein isoform 1 were examined to evaluate the regulatory action of CENPK in RKO cells.Significantly delayed xenograft tumor emergence,slower growth rate,and lower final tumor weight and volume were observed in the CENPK short hairpin RNA virus infected group compared with the CENPK negative control group.The CENPK gene interference inhibited the proliferation of RKO cells in vitro and in vivo.The lentivirus-mediated shRNA interference of CENPK inhibited the proliferation of RKO and HCT116 colon cancer cells,with overexpression of the CUL4A.CONCLUSION We indicated a potential role of CENPK in promoting tumor proliferation,and it may be a novel diagnostic and prognostic biomarker for CRC.展开更多
Using indirect immunofluorescence (IIF), an anti-centromere protein CenpG-serum was verified. Western blot of the protein extracts of 31 samples of breast cancer tissues and their normal (not cancerous ) tissues a lit...Using indirect immunofluorescence (IIF), an anti-centromere protein CenpG-serum was verified. Western blot of the protein extracts of 31 samples of breast cancer tissues and their normal (not cancerous ) tissues a little far away from them in the same individuals showed that, in the majority of the tests (71%), centromere protein CenpG over expressed in breast cancer tissues. And moreover, a kind of protein component whose molecular weight is 43 kd, and which can be recognized by anti-CenpG serum was found in two of the cancer samples. The results suggested that CenpG (together whith it, there may be other relative components),which has been found and named recently, may be related to cancer,and its differential expressing is probably related to malignant cell proliferation.展开更多
The centromere is an essential chromosome site at which the kinetochore forms and loads proteins needed for faithful segregation during the cell cycle and meiosis（Houben et al., 1999;Cleveland et al.,2003;Ma et al.,2...The centromere is an essential chromosome site at which the kinetochore forms and loads proteins needed for faithful segregation during the cell cycle and meiosis（Houben et al., 1999;Cleveland et al.,2003;Ma et al.,2007;Birchler and Han,2009）.Centromere specific sequences such as tandem repeats or transposable elements evolve quickly both within and between the species but have conserved kinetochore proteins（Henikoff and Furuyama,2010）.展开更多
Objective To investigate the expression of centromere protein-C （CENP-C） in villus tissue of the first-trimester spontaneous abortion （SA） and the correlation study of CENP-C expression with chromosome segregation...Objective To investigate the expression of centromere protein-C （CENP-C） in villus tissue of the first-trimester spontaneous abortion （SA） and the correlation study of CENP-C expression with chromosome segregation. Methods Fluorescence in situ hybridization （FISH） and G-banded karyotype analysis were used to detect the numerical chromosome abnormality in 94 villus tissues of women with SA. The participants were separated into case group （n=30） and control group （n--30） according to the results with FISH. The qRT-PCR and Western blotting analysis were used to assess the expression level of CENP-C. Results Forty-eight （51.06%） cases had observed the numerical chromosome abnormality, including 30positive cases and the positive rate was 31.91%. The main types of variation included trisomy 16, 21, 22, X monosomy and triploid. The expression levels of CENP-C mRNA and protein in case group were statistically higher than that in control group （P〈0.05）. Conclusion Expression of CENP-C in the villus tissues of women might be related to SA induced by chromosomal aneuploid.展开更多
An awned rice（Oryza sativa） plant carrying a tiny extra chromosome was discovered among the progeny of a telotrisomic line 2nt4L. Fluorescence in situ hybridization（FISH） using chromosome specific BAC clones revea...An awned rice（Oryza sativa） plant carrying a tiny extra chromosome was discovered among the progeny of a telotrisomic line 2nt4L. Fluorescence in situ hybridization（FISH） using chromosome specific BAC clones revealed that this extra chromosome was a ring chromosome derived from part of the long arm of chromosome 4. So the aneuploidy plant was accordingly named as 2nt4L ring. We did not detect any Cent O FISH signals on the ring chromosome, and found only the centromeric probe Centromeric Retrotransposon of Rice（CRR） was co-localized with the centromere-specific histone CENH3 as revealed by sequential FISH after immunodetection. The extra ring chromosome exhibited a unique segregation pattern during meiosis, including no pairing between the ring chromosome and normal chromosome 4during prophase I and pre-separation of sister chromatids at anaphase I.展开更多
基金the National Natural Science Foundation of China(31991212)the National Key Research and Development Program of China(2022YFF1003303).
文摘The Triticum-Aegilops complex groups demonstrated high cross-affinity with each other to overcome the barriers of distant hybridization(Loureiro et al.,2023).Distant hybridization involves two distinct yet closely related events:hybridization and genome doubling.Previous studies have indicated that bursts of transposable elements(TEs)can occur as a consequence or concomitant to hybridization or genome duplication(Parisod et al.,2010).This raises an important scientific question regarding how the TEs-rich centromere region copes with genomic shock(McClintock,1984).The Triticum-Aegilops species complexes,particularly in the F1,So,and subsequent early generations resulting from successive selfcrossing,offer an opportunity to investigate whether the centromere environment undergoes reconstruction and the associated mechanisms that maintain genomic stability.
基金supported by the Program for New Century Excellent Talents in University (No. NCET-07-0811)the Natural Science Foundation of China (No. 30771208)
文摘The centromere is a defining region that mediates chromosome attachment to kinetochore microtubules and proper segregation of the sister chromatids. Intriguingly, satellite DNA and centromeric retrotransposon as major DNA constituents of centromere showed baffling diversification and species-specific. However, the key kinetochore proteins are conserved in both plants and animals, particularly the centromere-specific histone H3-1ike protein （CENH3） in all functional centromeres. Recent studies have highlighted the importance of epigenetic mechanisms in the establishment and maintenance of centromere identity. Here, we review the progress and compendium of research on plant centromere in the light of recent data.
基金supported by the National Natural Science Foundation of China(32230029,81925015,32270898,32400709,and 32400714)the National Key Research and Development Program of China(2022YFC2702600)+2 种基金the China Postdoctoral Science Foundation(2024M760638 and 2024M760640)the Science and Technology Project of Guangzhou(2023A03J0886)the plan on enhancing scientific research in GMU.
文摘R-loops play various roles in many physiological processes,however,their role in meiotic division remains largely unknown.Here we show that R-loops and their regulator RNase H1 are present at centromeres during oocyte meiotic divisions.Proper centromeric R-loops are essential to ensure chromosome alignment in oocytes during metaphase I(MI).Remarkably,both Rnaseh1 knockout and overexpression in oocytes lead to severe spindle assembly defects and chromosome misalignment due to dysregulation of R-loops at centromeres.Furthermore,we find that replication protein A(RPA)is recruited to centromeric R-loops,facilitating the deposition of ataxia telangiectasia-mutated and Rad3-related(ATR)kinase at centromeres by interacting with the ATR-interaction protein(ATRIP).The ATR kinase deposition triggers the activity of CHK1,stimulating the phosphorylation of Aurora B to finally promote proper spindle assembly and chromosome alignment at the equatorial plate.Most importantly,the application of ATR,CHK1,and Aurora B inhibitors could efficiently rescue the defects in spindle assembly and chromosome alignment due to RNase H1 deficiency in oocytes.Overall,our findings uncover a critical role of R-loops during mouse oocyte meiotic divisions,suggesting that dysregulation of R-loops may be associated with female infertility.Additionally,ATR,CHK1,and Aurora B inhibitors may potentially be used to treat some infertile patients.
基金supported by the National Natural Science Foundation of China (32170645)the National Key Research and Development Program of China (2021YFF1000900).
文摘Centromere positioning and organization are crucial for genome evolution;however,research on centro-mere biology is largely influenced by the quality of available genome assemblies.Here,we combined Oxford Nanopore and Pacific Biosciences technologies to de novo assemble two high-quality reference genomes for Gossypium hirsutum(TM-1)and Gossypium barbadense(3-79).Compared with previously published reference genomes,our assemblies show substantial improvements,with the contig N50 improved by 4.6-fold and 5.6-fold,respectively,and thus represent the most complete cotton genomes to date.These high-quality reference genomes enable us to characterize 14 and 5 complete centromeric regions for G.hirsutum and G.barbadense,respectively.Our data revealed that the centromeres of allotetraploid cotton are occupied by members of the centromeric repeat for maize(CRM)and Tekay long terminal repeat families,and the CRM family reshapes the centromere structure of the At subgenome after polyploidization.These two intertwined families have driven the convergent evolution of centromeres between the two subgenomes,ensuring centromere function and genome stability.In addition,the reposi-tioning and high sequence divergence of centromeres between G.hirsutum and G.barbadense have contributed to speciation and centromere diversity.This study sheds light on centromere evolution in a sig-nificant crop and provides an alternative approach for exploring the evolution of polyploid plants.
基金supported by the National Natural Science Foundation of China(32188102,32372148)Innovation Program of Chinese Academy of Agricultural Sciences,the Youth Innovation of Chinese Academy of Agricultural Sciences(Y20230C36)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2023B1515020053)the Youth Program of Guangdong Basic and Applied Research(2021A1515111123)。
文摘Rice(Oryza sativa)is a significant crop worldwide with a genome shaped by various evolutionary factors.Rice centromeres are crucial for chromosome segregation,and contain some unreported genes.Due to the diverse and complex centromere region,a comprehensive understanding of rice centromere structure and function at the population level is needed.We constructed a high-quality centromere map based on the rice super pangenome consisting of a 251-accession panel comprising both cultivated and wild species of Asian and African rice.We showed that rice centromeres have diverse satellite repeat CentO,which vary across chromosomes and subpopulations,reflecting their distinct evolutionary patterns.We also revealed that long terminal repeats(LTRs),especially young Gypsy-type LTRs,are abundant in the peripheral CentO-enriched regions and drive rice centromere expansion and evolution.Furthermore,high-quality genome assembly and complete telomere-to-telomere(T2T)reference genome enable us to obtain more centromeric genome information despite mapping and cloning of centromere genes being challenging.We investigated the association between structural variations and gene expression in the rice centromere.A centromere gene,OsMAB,which positively regulates rice tiller number,was further confirmed by expression quantitative trait loci,haplotype analysis and clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein9 methods.By revealing the new insights into the evolutionary patterns and biological roles of rice centromeres,our finding will facilitate future research on centromere biology and crop improvement.
基金supported by the National Natural Science Foundation of China(31991212,31920103006)。
文摘Centromeres play a vital role in cellular division by facilitating kinetochore assembly and spindle attachments.Despite their conserved functionality,centromeric DNA sequences exhibit rapid evolution,presenting diverse sizes and compositions across species.The functional significance of rye centromeric DNA sequences,particularly in centromere identity,remains unclear.In this study,we comprehensively characterized the sequence composition and organization of rye centromeres.Our findings revealed that these centromeres are primarily composed of long terminal repeat retrotransposons(LTR-RTs)and interspersed minisatellites.We systematically classified LTR-RTs into five categories,highlighting the prevalence of younger CRS1,CRS2,and CRS3 of CRSs(centromeric retrotransposons of Secale cereale)were primarily located in the core centromeres and exhibited a higher association with CENH3 nucleosomes.The minisatellites,mainly derived from retrotransposons,along with CRSs,played a pivotal role in establishing functional centromeres in rye.Additionally,we observed the formation of R-loops at specific regions of CRS1,CRS2,and CRS3,with both rye pericentromeres and centromeres exhibiting enrichment in R-loops.Notably,these R-loops selectively formed at binding regions of the CENH3 nucleosome in rye centromeres,suggesting a potential role in mediating the precise loading of CENH3 to centromeres and contributing to centromere specification.Our work provides insights into the DNA sequence composition,distribution,and potential function of R-loops in rye centromeres.This knowledge contributes valuable information to understanding the genetics and epigenetics of rye centromeres,offering implications for the development of synthetic centromeres in future plant modifications and beyond.
基金supported by the National Key Research and Development Program of China(2023YFF1000100 and 2023YFA0914601)the Special Funds for Science Technology Innovation and Industrial Development of Shenzhen Dapeng New District(PT202101-01).
文摘Increasing number of structural variations(SVs)have been identified as causative mutations for diverse agronomic traits.However,the systematic exploration of SVs quantity,distribution,and contribution in wheat was lacking.Here,we report high-quality gene-based and SV-based pangenomes comprising 22 hexaploid wheat assemblies showing a wide range of chromosome size,gene number,and TE component,which indicates their representativeness of wheat genetic diversity.Pan-gene analyses uncover 140,261 distinct gene families,of which only 23.2%are shared in all accessions.Moreover,we build a∼16.15 Gb graph pangenome containing 695,897 bubbles,intersecting 5132 genes and 230,307 cis-regulatory regions.Pairwise genome comparisons identify∼1,978,221 non-redundant SVs and 497 SV hotspots.Notably,the density of bubbles as well as SVs show remarkable aggregation in centromeres,which probably play an important role in chromosome plasticity and stability.As for functional SVs exploration,we identify 2769 SVs with absolute relative frequency differences exceeding 0.7 between spring and winter growth habit groups.Additionally,several reported functional genes in wheat display complex structural graphs,for example,PPD-A1,VRT-A2,and TaNAAT2-A.These findings deepen our understanding of wheat genetic diversity,providing valuable graphical pangenome and variation resources to improve the efficiency of genome-wide association mapping in wheat.
基金supported by the National Key R&D Program of China(2022YFF1000100,2023YFD1300300)the National Natural Science Foundation of China(31572388,31972525)the China Agriculture Research System of MOF and MARA(CARS-41)。
文摘Background Chickens and ducks are vital sources of animal protein for humans.Recent pangenome studies suggest that a single genome is insufficient to represent the genetic information of a species,highlighting the need for more comprehensive genomes.The bird genome has more than tens of microchromosomes,but comparative genomics,annotations,and the discovery of variations are hindered by inadequate telomere-to-telomere level assemblies.We aim to complete the chicken and duck genomes,recover missing genes,and reveal common and unique chromosomal features between birds.Results The near telomere-to-telomere genomes of Silkie Gallus gallus and Mallard Anas platyrhynchos were successfully assembled via multiple high-coverage complementary technologies,with quality values of 36.65 and 44.17 for Silkie and Mallard,respectively;and BUSCO scores of 96.55%and 96.97%for Silkie and Mallard,respectively;the mapping rates reached over 99.52%for both assembled genomes,these evaluation results ensured high completeness and accuracy.We successfully annotated 20,253 and 19,621 protein-coding genes for Silkie and Mallard,respectively,and assembled gap-free sex chromosomes in Mallard for the first time.Comparative analysis revealed that microchromosomes differ from macrochromosomes in terms of GC content,repetitive sequence abundance,gene density,and levels of 5mC methylation.Different types of arrangements of centromeric repeat sequence centromeres exist in both Silkie and the Mallard genomes,with Mallard centromeres being invaded by CR1.The highly heterochromatic W chromosome,which serves as a refuge for ERVs,contains disproportionately long ERVs.Both Silkie and the Mallard genomes presented relatively high 5mC methylation levels on sex chromosomes and microchromosomes,and the telomeres and centromeres presented significantly higher 5mC methylation levels than the whole genome.Finally,we recovered 325 missing genes via our new genomes and annotated TNFA in Mallard for the first time,revealing conserved protein structures and tissue-specific expression.Conclusions The near telomere-to-telomere assemblies in Mallard and Silkie,with the first gap-free sex chromosomes in ducks,significantly enhanced our understanding of genetic structures in birds,specifically highlighting the distinctive chromosome features between the chicken and duck genomes.This foundational work also provides a series of newly identified missing genes for further investigation.
基金This study was reviewed and approved by the Ethic Committee of Medical College of Henan Vocational University of Science and Technology(Approval No.HVUYL414101416920231017001)all participants signed a written informed consent.
文摘BACKGROUND Centromere protein A(CENPA)exhibits an increased expression level in primary human rectal cancer tissues,but its role has not been investigated.AIM To clarify the specific role and mechanism of CENPA in rectal cancer progression.METHODS CENPA protein expression in rectal cancer tissues and cell lines were detected.CENPA was overexpressed and knocked down in SW837 and SW480 cells,and proliferation,invasion,apoptosis and epithelial-mesenchymal transition(EMT)marker protein levels were examined.O6-methylguanine DNA methyltransferase(MGMT)promoter methylation was assessed with methylation-specific poly-merase chain reaction.Co-immunoprecipitation assay verified the interaction between MGMT and protein tyrosine phosphatase nonreceptor type 4(PTPN4).SW837 cells with CENPA knockdown were injected subcutaneously into mice,and tumor growth was examined.RESULTS CENPA was upregulated in rectal cancer tissues and cell lines.CENPA overex-pression promoted proliferation,invasion and EMT,and inhibited apoptosis in rectal cancer cells.Whereas CENPA knockdown showed the opposite results.Moreover,CENPA inhibited MGMT expression by promoting DNA methyltrans-ferase 1-mediated MGMT promoter methylation.MGMT knockdown abolished the CENPA knockdown-mediated inhibition of rectal cancer cell progression.MGMT increased PTPN4 protein stability by inhibiting PTPN4 ubiquitination degradation via competing with ubiquitin-conjugating enzyme E2O for interacting with PTPN4.PTPN4 knockdown abolished the inhibitory effects of MGMT overexpression on rectal cancer cell progression.Moreover,CENPA knockdown inhibited xenograft tumor growth in vivo.CONCLUSION CENPA knockdown inhibited rectal cancer cell growth and attenuated xenograft tumor growth through regulating the MGMT/PTPN4 axis.
基金supported by the National Natural Science Foundation of China(Grant No.31071083)National Science Foundation(No.DBI0922703).
文摘The centromere is a highly organized structure mainly composed of repeat sequences,which make this region extremely difficult for sequencing and other analyses.It plays a conserved role in equal division of chromosomes into daughter cells in both mitosis and meiosis.However,centromere sequences show notable plasticity.In a dicentric chromosome,one of the centromeres can become inactivated with the underlying DNA unchanged.Furthermore,formerly inactive centromeres can regain activity under certain conditions.In addition,neocentromeres without centromeric repeats have been found in a wide spectrum of species.This evidence indicates that epigenetic mechanisms together with centromeric sequences are associated with centromere specification.
基金supported by grants from the Biological Breeding-National Science and Technology Major Project(2024ZD04079)the National Natural Science Foundation of China(32370261).
文摘Dear Editor,Legumes,including soybean and alfalfa,are vital agricultural crops worldwide,providing high-quality protein and oil sources for humans and animals.In addition,legumes also provide nitrogen for soil improvement,benefiting from their symbiotic associations with nitrogen-fixing bacteria.
基金supported by the grants of the National High Technology Research and Development Program("863"Program) of China(No.2011AA100101)the Special Financial Grant from the China Postdoctoral Science Foundation (No.2012T50157),and 2011 Collaborative Innovation Plan of the Ministry Of Education of China
文摘Wheat-rye addition and substitution lines and their self progenies revealed variations in telomeric heterochromatin and centromeres, Furthermore, a mitotically unstable dicentric chromosome and stable multicentric chromosomes were observed in the progeny of a Chinese Spring-lmperial rye 3R addition line. An unstable multicentric chromosome was found in the progeny of a 6R/6D substitution line. Drastic variation of terminal heterochromatin including movement and disappearance of terminal heterochromatin occurred in the progeny of wheat- rye addition line 3R, and the 5RS ditelosomic addition line. Highly stable minichromosomes were observed in the progeny ofa monosomic 4R addition line, a ditelosomic 5RS addition line and a 6R/6D substitution line. Minichromosomes, with and without the FISH signals for telomeric DNA （TTTAGGG）n, derived from a monosomic 4R addition line are stable and transmissible to the next generation. The results indicated that centromeres and terminal heterochromatin can be profoundly altered in wheat-rye hybrid derivatives.
基金the Joint Funds for the Innovation of Science and Technology Program of Fujian Province,China(2018Y9110)the Natural Science Foundation of Fujian Province,China,(2020J011126)the China Postdoctoral Science Foundation(2021T140468).
文摘Background:Stemness and chemoresistance contribute to cervical cancer recurrence and metastasis.In the current study,we determined the relevant players and role of N^(6)-methyladenine(m^(6)A)RNA methylation in cervical cancer progression.Methods:The roles of m^(6)A RNA methylation and centromere protein K(CENPK)in cervical cancer were analyzed using bioinformatics analysis.Methylated RNA immunoprecipitation was adopted to detect m^(6)A modification of CENPK mRNA.Human cervical cancer clinical samples,cell lines,and xenografts were used for analyzing gene expression and function.Immunofluorescence staining and the tumorsphere formation,clonogenic,MTT,and EdU assays were performed to determine cell stemness,chemoresistance,migration,invasion,and proliferation in HeLa and SiHa cells,respectively.Western blot analysis,co-immunoprecipitation,chromatin immunoprecipitation,and luciferase reporter,cycloheximide chase,and cell fractionation assays were performed to elucidate the underlying mechanism.Results:Bioinformatics analysis of public cancer datasets revealed firm links between m^(6)A modification patterns and cervical cancer prognosis,especially through ZC3H13-mediated m^(6)A modification of CENPK mRNA.CENPK expression was elevated in cervical cancer,associated with cancer recurrence,and independently predicts poor patient prognosis[hazard ratio=1.413,95%confidence interval=1.078−1.853,P=0.012].Silencing of CENPK prolonged the overall survival time of cervical cancer-bearing mice and improved the response of cervical cancer tumors to chemotherapy in vivo(P<0.001).We also showed that CENPK was directly bound to SOX6 and disrupted the interactions of CENPK withβ-catenin,which promotedβ-catenin expression and nuclear translocation,facilitated p53 ubiquitination,and led to activation of Wnt/β-catenin signaling,but suppression of the p53 pathway.This dysregulation ultimately enhanced the tumorigenic pathways required for cell stemness,DNA damage repair pathways necessary for cisplatin/carboplatin resistance,epithelial-mesenchymal transition involved in metastasis,and DNA replication that drove tumor cell proliferation.Conclusions:CENPK was shown to have an oncogenic role in cervical cancer and can thus serve as a prognostic indicator and novel target for cervical cancer treatment.
文摘A thermo-insensitive pale green leaf mutant （pgl2） was isolated from T-DNA inserted transgenic lines of rice （Oryza sativa L. subsp, japonica cv. Nipponbare）. Genetic analysis indicated that the phenotype was caused by a recessive mutation in a single nuclear-encoded gene. To map the PGL2gene, an F2 population was constructed by crossing the mutant with Longtefu （Oryza sativa L. subsp, indica）. The PGL2 locus was roughly linked to SSR marker RM331 on chromosome 8. To finely map the gene, 14 new InDel markers were developed around the marker, and PGL2 was further mapped to a 2.37 Mb centromeric region. Analysis on chlorophyll contents of leaves showed that there was no obvious difference between the mutant and the wild type in total chlorophyll （Chl） content, while the ratio of Chl a / Chl b in the mutant was only about 1, which was distinctly lower than that in the wild type, suggesting that the PGL2 gene was related to the conversion between Chl a and Chl b. Moreover, the method of primer design around the centromeric region was discussed, which would provide insight into fine mapping of the functional genes in plant centromeres.
基金supported by the grants from the National Natural Science Foundation of China (Nos.31071083 and 31130033)the National Science Foundation of USA (No.DBI 0922703)
文摘Plant centromeres are generally composed of tandem arrays of simple repeats that form a complex chromosome locus where the kinetochore forms and microtubules attach during mitosis and meiosis. Each chromosome has one centromere region, which is essential for accurate division of the genetic material. Recently, chromosomes containing two centromere regions （called dicentric chromosomes） have been found in maize and wheat. Interestingly, some dicentric chromosomes are stable because only one centromere is active and the other one is inactivated. Because such arrays maintain their typical structure for both active and inactive centromeres, the specification of centromere activity has an epigenetic component independent of the DNA sequence. Under some circumstances, the inactive centromeres may recover centromere function, which is called centromere reactivation. Recent studies have highlighted the important changes, such as DNA methylation and histone modification, that occur during centromere inactivation and reactivation.
基金the National Natural Science Foundation of China,No.81860416 and No.22168028Inner Mongolia Autonomous Region Grassland Talent Innovation Talent Team Fund,No.2019Inner Mongolia Natural Science Fund,No.2021MS02005.
文摘BACKGROUND Colorectal cancer(CRC)is one of the most common malignant tumors worldwide.The identification of novel diagnostic and prognostic biomarkers for CRC is a key research imperative.Immunohistochemical analysis has revealed high expression of centromere protein K(CENPK)in CRC.However,the role of CENPK in the progression of CRC is not well characterized.AIM To evaluate the effects of knockdown of CENPK and overexpression of Cullin 4A(CUL4A)in RKO and HCT116 cells.METHODS Human colon cancer samples were collected and tested using a human gene expression chip.We identified CENPK as a potential oncogene for CRC based on bioinformatics analysis.In vitro experiments verified the function of this gene.We investigated the expression of CENPK in RKO and HCT116 cells using quantitative polymerase chain reaction(qPCR),western blot,and flow cytometry.The effect of short hairpin RNA(shRNA)virus-infected RKO cells on tumor growth was evaluated in vivo using quantitative analysis of fluorescence imaging.To evaluate the effects of knockdown of CENPK and overexpression of CUL4A in RKO and HCT116 cells,we performed a series of in vitro experiments,using qPCR,western blot,MTT assay,and flow cytometry.RESULTS We demonstrated overexpression of CENPK in human colon cancer samples.CENPK was an independent risk factor in patients with CRC.The downstream genes FBX32,CUL4A,and Yesassociated protein isoform 1 were examined to evaluate the regulatory action of CENPK in RKO cells.Significantly delayed xenograft tumor emergence,slower growth rate,and lower final tumor weight and volume were observed in the CENPK short hairpin RNA virus infected group compared with the CENPK negative control group.The CENPK gene interference inhibited the proliferation of RKO cells in vitro and in vivo.The lentivirus-mediated shRNA interference of CENPK inhibited the proliferation of RKO and HCT116 colon cancer cells,with overexpression of the CUL4A.CONCLUSION We indicated a potential role of CENPK in promoting tumor proliferation,and it may be a novel diagnostic and prognostic biomarker for CRC.
文摘Using indirect immunofluorescence (IIF), an anti-centromere protein CenpG-serum was verified. Western blot of the protein extracts of 31 samples of breast cancer tissues and their normal (not cancerous ) tissues a little far away from them in the same individuals showed that, in the majority of the tests (71%), centromere protein CenpG over expressed in breast cancer tissues. And moreover, a kind of protein component whose molecular weight is 43 kd, and which can be recognized by anti-CenpG serum was found in two of the cancer samples. The results suggested that CenpG (together whith it, there may be other relative components),which has been found and named recently, may be related to cancer,and its differential expressing is probably related to malignant cell proliferation.
文摘The centromere is an essential chromosome site at which the kinetochore forms and loads proteins needed for faithful segregation during the cell cycle and meiosis（Houben et al., 1999;Cleveland et al.,2003;Ma et al.,2007;Birchler and Han,2009）.Centromere specific sequences such as tandem repeats or transposable elements evolve quickly both within and between the species but have conserved kinetochore proteins（Henikoff and Furuyama,2010）.
基金supported by the Natural Science Foundation of Shanxi province[2012021035-1]
文摘Objective To investigate the expression of centromere protein-C （CENP-C） in villus tissue of the first-trimester spontaneous abortion （SA） and the correlation study of CENP-C expression with chromosome segregation. Methods Fluorescence in situ hybridization （FISH） and G-banded karyotype analysis were used to detect the numerical chromosome abnormality in 94 villus tissues of women with SA. The participants were separated into case group （n=30） and control group （n--30） according to the results with FISH. The qRT-PCR and Western blotting analysis were used to assess the expression level of CENP-C. Results Forty-eight （51.06%） cases had observed the numerical chromosome abnormality, including 30positive cases and the positive rate was 31.91%. The main types of variation included trisomy 16, 21, 22, X monosomy and triploid. The expression levels of CENP-C mRNA and protein in case group were statistically higher than that in control group （P〈0.05）. Conclusion Expression of CENP-C in the villus tissues of women might be related to SA induced by chromosomal aneuploid.
基金supported by grants from the National Natural Science Foundation of China (Nos. U1302261, 31360260 and 31401357).
文摘An awned rice（Oryza sativa） plant carrying a tiny extra chromosome was discovered among the progeny of a telotrisomic line 2nt4L. Fluorescence in situ hybridization（FISH） using chromosome specific BAC clones revealed that this extra chromosome was a ring chromosome derived from part of the long arm of chromosome 4. So the aneuploidy plant was accordingly named as 2nt4L ring. We did not detect any Cent O FISH signals on the ring chromosome, and found only the centromeric probe Centromeric Retrotransposon of Rice（CRR） was co-localized with the centromere-specific histone CENH3 as revealed by sequential FISH after immunodetection. The extra ring chromosome exhibited a unique segregation pattern during meiosis, including no pairing between the ring chromosome and normal chromosome 4during prophase I and pre-separation of sister chromatids at anaphase I.
