Project description:The nonrandom distribution of meiotic recombination shapes patterns of inheritance and genome evolution, but chromosomal features governing this distribution are poorly understood. Formation of the DNA double-strand breaks (DSBs) that initiate recombination results in accumulation of Spo11 protein covalently bound to small DNA fragments. We show here that sequencing these fragments provides a genome-wide DSB map of unprecedented resolution and sensitivity. We use this map to explore the influence of large-scale chromosome structures, chromatin, transcription factors, and local sequence composition on DSB distributions. Our analysis supports the view that the recombination terrain is molded by combinatorial and hierarchical interaction of factors that work on widely different size scales. Mechanistic aspects of DSB formation and early processing steps are also uncovered. This map illuminates the occurrence of DSBs in repetitive DNA elements, repair of which can lead to chromosomal rearrangements. We discuss implications for evolutionary dynamics of recombination hotspots. We deep sequenced 4 samples of Spo11 oligos on Roche 454 platform. Three samples are technical replicates of Spo11 oligo products prepared from one meiotic culture and the fourth sample was prepared from an independent culture.
Project description:In this study, we employed a special size fractionation and cDNA library construction method followed by 454 deep sequencing to systematically profile rice intermediate-size ncRNAs. Our analysis resulted in the identification of 1349 ncRNAs in total, including 754 novel ncRNAs of an unknown functional category. Chromosome distribution of all identified ncRNAs showed no strand bias, and displayed a pattern similar to that observed in protein-coding genes with few chromosome dependencies. More than half of the ncRNAs were centered around the plus-strand of the 5’ and 3’ termini of the coding regions. The majority of the novel ncRNAs were rice specific, while 78% of the small nucleolar RNAs (snoRNAs) were conserved. Tandem duplication drove the expansion of over half of the snoRNA gene families. Furthermore, 90% of the snoRNA candidates were shown to produce small RNAs between 20-30 nt, 80% of which were associated with ARGONAUT proteins generally, and AGO1b in particular. Overall, our findings provide a comprehensive view of an intermediate-size non-coding transcriptome in a monocot species, which will serve as a useful platform for an in-depth analysis of ncRNA functions. Examination of non-coding RNA in 2 stages in Oryza sativa, using 454 deep sequecing
Project description:The RNA-induced silencing complex, comprising Argonaute and guide RNA, mediates RNA interference. Here we report the 3.2 M-CM-^E crystal structure of Kluyveromyces Argonaute (KpAGO) fortuitously complexed with guide RNA originating from small-RNA duplexes autonomously loaded by recombinant KpAGO. Despite their diverse sequences, guide-RNA nucleotides 1-8 are positioned similarly, with sequence-independent contacts to bases, phosphates and 2'-hydroxyl groups pre-organizing the backbone of nucleotides 2-8 in a near-A-form conformation. Compared with prokaryotic Argonautes, KpAGO has numerous surface-exposed insertion segments, with a cluster of conserved insertions repositioning the N domain to enable full propagation of guide-target pairing. Compared with Argonautes in inactive conformations, KpAGO has a hydrogen-bond network that stabilizes an expanded and repositioned loop, which inserts an invariant glutamate into the catalytic pocket. Mutation results and analogies to Ribonuclease H indicate that insertion of this glutamate finger completes a universally conserved catalytic tetrad, thereby activating Argonaute for cleavage. High-throughput sequencing of cellular RNAs containing both a 5'-monophosphate group and a poly(A) tail. To identify Argonaute-dependent cleavage tags, sequencing libraries were prepared from M-NM-^Txrn1 and M-NM-^Txrn1 M-NM-^Tago1 strains.
Project description:Long non-coding RNAs (lncRNA) constitute a large fraction of mammalian transcriptomes that still remains unexplored, mainly due to the lack of comprehensive, high-quality lncRNA annotation that limits the possibility to fully explore their functional capacity. We have developed RACE-seq, an experimental workflow based on RACE (Rapid Amplification of cDNA Ends) and long read RNA sequencing, aimed at both rare isoform discovery and better definition of gene boundaries. We applied 3â and 5â RACE-seq on 398 low-expressed GENCODE v7 lncRNA genes in seven human tissues (brain, testis, heart, kidney, liver, lung and spleen). The sequences obtained led to the discovery of 2,641 on-target, previously unknown alternative transcripts. Novel isoforms extended 60% of the 398 targeted lncRNA loci further in either 5' or 3', and often reached genome hallmarks typical of gene boundaries. In parallel, we used nested RACE-seq, and confirmed that nested RACE-seq has overwhelmingly better sensitivity than its standard counterpart.
Project description:We used massively parallel pyrosequencing to discover and characterize microRNAs (miRNAs) expressed in human embryonic stem cells (hESCs). Sequencing of small RNA cDNA libraries derived from undifferentiated hESC and from isogenic differentiating cultures yielded a total of 425,505 high-quality sequence reads. A custom data analysis pipeline delineated expression profiles for 191 previously annotated miRNAs, 36 novel miRNAs highly conserved across vertebrates, and 291 novel candidate miRNAs. A set of nine known and seven novel miRNAs were expressed in undifferentiated hESC and then strongly down-regulated with differentiation. Predicted mRNA targets of these miRNAs exhibited statistically significant enrichment for Gene Ontology functional categories relevant to ESC biology. Our study reveals that hESC express a larger complement of miRNAs than previously appreciated and it provides a resource for future studies of miRNA-mediated regulation in human embryonic stem cells. Two samples were 454 sequenced: undifferentiated human embryonic stem cells and differentiated human embryonic stem cells.
Project description:Purpose: Zinc deficiency (ZnD) and iron deficiency (FeD), excess Zn (ZnE) and cadmium exposure (CdE) are major environmental problems for crop cultivation. Methods: Applying Tag-Seq technology to leaves of Brassica rapa grown under FeD, ZnD, ZnE or CdE conditions, with normal conditions as a control, we examined global gene expression changes and compared the expression patterns of multiple paralogs. Results: We identified 812, 543, 331 and 447 differentially expressed genes under FeD, ZnD, ZnE and CdE conditions, respectively, in B. rapa leaves.Further analysis revealed that genes associated with Zn, Fe and Cd responses tended to be over-retained in the B. rapa genome. Most of these multiple-copy genes showed the same direction of expression change under stress conditions. Conclusion: We conclude that the duplicated genes involved in trace element responses in B. rapa are functionally redundant, making the regulatory network more complex in B. rapa than in Arabidopsis thaliana. In total, there were 15 Digital gene expression libraries, one for each of the three replicates under the four trace metal element treatments and normal nutrient supply conditions as a control.
Project description:We report the DNA-methylation profiling of 10 regions selected from the DLK1-DIO3 domain on chromosome 14q32 in BM/PB samples from patients with acute promyelocytic leukaemia (APL), other subclasses of acute myeloid leukaemia and healthy donors, using high-throughput amplicon bisulfite sequencing with Roche 454 technology. We identify monoallelic-hypermethylation in APL only at the differentially methylated region (DMR) located upstream from the MEG3 gene (MEG3-DMR), whereas no changes in the DNA methylation profile were detected at the imprinting control region of the domain (IG-DMR) among the samples analysed. We show that the expression profile of 6 miRNAs clustered downstream from the MEG3-DMR correlates with the methylation profile at both DMRs. We demonstrate that miRNAs expression negatively correlates with DNA-methylation at the IG-DMR and MEG3 gene-body, whereas the correlation was positive for the CpGs located in the promoter of MEG3, including the binding sites for the insulator CTCF. We propose a loss of imprinting at the CTCF binding sites in patients with APL. These results are consistent with the previously reported DLK1-DIO3 miRNAs overexpression in APL, indicating a possible involvement of these ncRNAs in the pathogenesis of the disease. Investigation of the epigenetic regulation of the miRNAs clustered in 14q32 by next-generation sequencing
Project description:Analysis of small RNAs with 5'p, 3'OH Small RNAs (18-32nt) expressed in purified male sperm, hermaphrodite oocytes, embryos, N2, glp-4(bn2), and eri-1(mg366) were cloned and sequenced by 454 and Illumina high-throughput sequencing.
Project description:Biomphalaria glabrata infection by the Schistosoma mansoni free-swimming miracidium and its subsequent development to the parasitic sporocyst stage is critical to establishment of viable infections and triggers a variety of physiological, biochemical and molecular changes. Here, we describe a genome-wide analysis of the S. mansoni miracidium and developing sporocyst. Keywords: life-cycle, development, host-interaction We generated transcriptomic profiles of the developing larval stages of Schistosoma mansoni using long serial analysis of gene expression (LongSAGE). Five cDNA libraries were constructed from miracidia and in vitro cultured 6- and 20-day old sporocysts maintained in sporocyst medium (SM) or in SM conditioned by previous cultivation with cells of the B. glabrata embryonic (Bge) cell line. From five libraries, 314,799 SAGE tags were sequenced and resulted in a total of 21,440 unique sequence tags. A total of 254 tags were differentially expressed during “conditioned” development and 236 tags were differentially expressed during “un-conditioned” development. In addition, 53 tags were found to be differentially expressed between 6-day conditioned and unconditioned sporocysts and 42 tags between 20-day conditioned and unconditioned sporocysts.
Project description:Oral susceptibility of Aedes aegypti mosquitoes to dengue viruses varies between different Aedes species and strains. However, the midgut-specific transcriptional profile that may produce this variation is presently obscure and was the subject of our investigation. The variation in active expression between dengue-2 susceptible (SUS) and refractory (REF) mosquitoes was investigated during the first critical 96 hours after infection Transcriptional profiles were mined from respective guts using the serial analysis of gene expression technique (SAGE) and libraries constructed from midguts obtained from mosquitoes that received a dengue-2 infected blood meal (DENV-2), a non infected blood meal (naive) or a 5% sucrose meal (SM). Here we report that variation between DENV-2 infected libraries versus respective naïve libraries revealed very few transcripts that were common and statistically significant in DENV-2 infected libraries. In addition, the expression profiles among libraries displayed up regulation of antisense transcripts especially in the SUS strain. A strong proclivity towards strain-specificity in differential expression was observed, which suggested an exclusive transcription that is likely up-regulated after DENV-2 infection Thirty Aedes aegypti female mosquitoes aged 4-5 days were transferred to 500 ml paper cups and offered a 5% sucrose meal (SM), a naïve blood meal or a dengue-2 (JAM 1409 strain) infectious blood meal, using standard artificial membrane feeders. Fully engorged females were isolated and maintained on a 5% sucrose solution ad libitum at 26oC and relative humidity till dissection