Project description:Centromeres typically contain repeat sequences, but centromere function does not necessarily depend on these sequences. In aneuploid wheat (Triticum aestivum) and wheat distant hybridization offspring, we found functional centromeres with dramatic changes to centromeric retrotransposon of wheat (CRW) sequences. CRW sequences were greatly reduced in the ditelosomic lines 1BS, 5DS, 5DL, and a wheat-Thinopyrum elongatum addition line. CRWs were completely lost in the ditelosomic line 4DS, but a 994 kb ectopic genomic DNA sequence was involved in de novo centromere formation on the 4DS chromosome. In addition, two ectopic sequences were incorporated in a de novo centromere in a wheat-Th. intermedium addition line. Centromeric sequences were also expanded to the chromosome arm in wide hybridizations. Stable alien chromosomes with two and three regions containing centromeric sequences were found in wheat-Th. elongatum hybrid derivatives, but only one is functional. In wheat-rye (Secale cereale) hybrids, rye centromere specific sequences spread to the chromosome arm and may cause centromere expansion. Thus, distant wheat hybridizations cause frequent and significant changes to the centromere via centromere misdivision, which may affect retention or loss of alien chromosomes in hybrids. ChIP-seq was carried out with anti-CENH3 antibody using material 4DS and control (Chinese Spring, CS as short).
Project description:De novo centromeres originate occasionally from non-centromeric regions of chromosomes, providing an excellent model system to study centromeric chromatin. The maize mini-chromosome Derivative 3-3 contains a de novo centromere, which was derived from a euchromatic site on the short arm of chromosome 9 that lacks traditional centromeric repeat sequences. Our previous study found that the CENH3 binding domain of this de novo centromere is only 288 kb with a high-density gene distribution with low-density of transposons. Here we applied next generation sequencing technology to analyze gene transcription, DNA methylation for this region. Our RNA-seq data revealed that active chromatin is not a barrier for de novo centromere formation. Bisulfite-ChIP-seq results indicate a slightly increased DNA methylation level after de novo centromere formation, reaching the level of a native centromere. These results provide insight into the mechanism of de novo centromere formation and subsequent consequences. RNA-seq was carried out using material from seedling and young leaves between control and Derivative 3-3. Bisulfite-ChIP-seq was carried out with anti-CENH3 antibodies using material from young leaves in Derivative 3-3.
Project description:We identified a newly formed dicentric chromosome (sDic-15) in maize from intrachromosomal recombination and BFB cycles, in which only one centromere is active. The centromeres lost CentC sequences and dramatic reduced the CRM sequences, but when the molecular features of functional centromeres such as CENH3 was examined, they were present. Immunolocalization analysis of phosphorylation of H3T3, H3ser-10 and H2A levels on this new centromere shows a pattern typical of a functional centromere. Meiotic analysis revealed that this dicentric chromosome is table and transmit very well. To examine the new sequences associated with CENH3 in this centromere, chromatin immunoprecipitation (ChIP) was carried out with anti-CENH3 antibodies and material from young seedlings with or without dicentric chromosome. We mapped the ChIP-Seq reads to the reference genome and found a 723kb region from the short arm of maize chromosome 9 involve the new centromere formation. This region is gene-poor and full of TEs, but genes in this region are transcribed. The original 723kb region shows a high DNA methylation level as native centromeres but had no significant change when it involved into new centromere formation. The reactivation of this newly formed centromere indicated that centromere reactivation may not dependent on the relatively intact DNA sequences or topology of original inactive centromere. ChIP-seq was carried out with anti-CENH3 antibodies using material from young seedlings with and without sDic-15 chromosome. For sDic-15, some ChIPed DNA was treated with sodium bisulfite and prepared for Illumina sequencing to test its methylation level.
Project description:The ability of centromeres to alternate between active and inactive states indicates significant epigenetic elements controlling centromere assembly and centromere function. In maize (Zea mays), misdivision of the B chromosome centromere on a translocation with the short arm of chromosome 9 (TB-9Sb) can produce many variants with varying centromere sizes and centromeric DNA sequences. In derivatives of TB-9Sb, we found a de novo centromere on chromosome telo-3-3, which has no canonical centromeric repeat sequences. This centromere is derived from a 288-kb region on the short arm of chromosome 9, and is 19 megabases (Mb) removed from the translocation breakpoint of chromosome 9 in TB-9Sb. This centromere is much smaller than normal ones but can be maintained through meiosis. The functional B centromere in progenitor telo2-2 is deleted from telo3-3 but some B-repeat sequences remain. The de novo centromere of telo3-3 becomes inactive in three further derivatives with new centromeres being formed elsewhere on the chromosomes. One such de novo centromere contains only 200-kb CENH3 binding domain. This 200-kb centromere is located 3 Mb removed from the translocation breakpoint in a new location. The deleted B centromere in telo3-3 is activated in two derivatives. Our results suggest that de novo centromere formation is more common than previously thought and can persist on chromosomal fragments without a canonical centromere providing implications for karyotype evolution. ChIP-seq was carried out with anti-CENH3 antibodies using material from young leaves with control, telo3-3 and its derivate.
Project description:This study introduced the use of cotton in 200µL tips, namely cotton HILIC as a convenient tool for enriching large-scale glycopeptides before MS analysis in this study. The optimal loading buffer for cotton HILIC was investigated by using mouse brain as a complex test sample. Subsequently, the performance of cotton HILIC was evaluated by comparing with other two commercial enrichment approaches, venusil HILIC and Oasis MAX in both mouse brain and seminal plasma. Moreover, capacity and recovery rate were evaluated using different milligram of cotton in 200µL tips. Thus, a simple, convenient, and cost-friendly cotton HILIC method was proposed to achieve highly selective intact glycopeptide profiling.
Project description:A small fragment from maize chromosome 3 was created by irradiation by Stadler and Roman and named Duplication 3a (or Dp3a). This small chromosome does not contain any detectable CentC and CRM sequences, but when molecular features of functional centromeres such as CENH3 and CENP-C were examined, they were present. Immunolocalization analysis of phosphorylation of Ser-10 of histone H3 levels on Dp3a shows a pattern typical of a functional centromere. Meiotic analysis revealed that sister chromatids divided equationally at meiosis I as do all small chromosomes examined to date in maize. To examine the sequences associated with CENH3, chromatin immunoprecipitation (ChIP) was carried out with anti-CENH3 antibodies using material from young seedlings with and without Dp3 chromosome as the tissue source. The ChIPed DNA sample was then labeled for FISH detection and prepared for Illumina sequencing.The ChIP-Seq reads were mapped to the B73 reference genome and a significant peak was detected in the Dp3a sample that span 350 kb of the long arm of chromosome 3, which is the candidate region for association with CENH3. ChIP-bisulfite-seq results indicated that there is a slightly increased DNA methylation level after the centromere formation, approaching the level similar to normal centromere regions. Collectively, the results suggest the formation of a de novo centromere on this fragment that initially must have started at the time of X-irradiation release from the progenitor chromosome. These observations add further evidence for the epigenetic nature of centromere function in maize. ChIP-seq was carried out with anti-CENH3 antibodies using material from young seedlings with and without Dp3a chromosome. For Dp3a, some ChIPed DNA was treated with sodium bisulfite and prepared for Illumina sequencing to test its methylation level.
Project description:Cotton is an excellent model for studying heterosis, crop domestication and bioengineering improvement. Chromatin profiling helps to reveal how histone modifications are involved in controlling differential gene expression between A and D subgenome in allotetraploid cotton. However, the detailed profiling and functional characterization of H3K27me3 and H3K4me3/H3K27me3 bivalent mark are still understudied in cotton. In this study, we conducted H3K4me3 and H3K27me3-related ChIP-seq followed by comprehensively characterizing their roles in regulating gene transcription in cotton. We found that H3K4me3 and H3K27me3 exhibited active and repressive roles in regulating expression of genes between A and D subgenome, respectively. Expression of H3K4me3-H3K27me3 bivalent genes was regulated by combinatorial actions of both marks and may be dominantly controlled by H3K4me3. More importantly, H3K4me3 exhibited enrichment levels, positioning and distance-related effects on expression levels of related genes. In addition, H3K4me3, H3K27me3 and bivalent mark can indirectly influence gene expression through TF-mediated regulatory networks. Thus, our study provides insights in functions of H3K4me3 and H3K27me3 in regulating differential gene expression between A and D subgenome in cotton.
Project description:Genomic approaches to the discovery of promoters for sustained expression in cotton (Gossypium hirsutum L.) under field conditions: expression analysis in transgenic cotton and Arabidopsis of a Rubisco small subunit promoter identified using EST sequence analysis and cDNA microarrays. Keywords: Promoter Discovery
Project description:Centromeres typically contain repeat sequences, but centromere function does not necessarily depend on these sequences. In aneuploid wheat (Triticum aestivum) and wheat distant hybridization offspring, we found functional centromeres with dramatic changes to centromeric retrotransposon of wheat (CRW) sequences. CRW sequences were greatly reduced in the ditelosomic lines 1BS, 5DS, 5DL, and a wheat-Thinopyrum elongatum addition line. CRWs were completely lost in the ditelosomic line 4DS, but a 994 kb ectopic genomic DNA sequence was involved in de novo centromere formation on the 4DS chromosome. In addition, two ectopic sequences were incorporated in a de novo centromere in a wheat-Th. intermedium addition line. Centromeric sequences were also expanded to the chromosome arm in wide hybridizations. Stable alien chromosomes with two and three regions containing centromeric sequences were found in wheat-Th. elongatum hybrid derivatives, but only one is functional. In wheat-rye (Secale cereale) hybrids, rye centromere specific sequences spread to the chromosome arm and may cause centromere expansion. Thus, distant wheat hybridizations cause frequent and significant changes to the centromere via centromere misdivision, which may affect retention or loss of alien chromosomes in hybrids.