Project description:Meiotic DNA double stranded breaks (DSBs) initiate genetic recombination in discrete areas of the genome called recombination hotspots. Although DSBs can be directly mapped using ChIP-Seq and antibody against ssDNA-associated proteins, genome-wide mapping of recombination hotspots in mammals is still a challenge due to the low frequency of recombination, high heterogeneity of the germ cell population and the relatively low efficiency of ChIP. To overcome these limitations we have developed a novel method, single-stranded DNA (ssDNA) sequencing (SSDS), that specifically detects protein-bound single-stranded DNA at DSB ends. SSDS consists of a computational framework for the specific detection of ssDNA-derived reads in a sequencing library and a new library preparation procedure for the enrichment of fragments originating from ssDNA. When applied to mapping meiotic DSBs, the use of SSDS reduces the non-specific dsDNA background more than ten-fold. Our method can be extended to other systems where the identification of ssDNA or DSBs is desired. Development and validation of the method, SSDS, for the specific detection of ssDNA-derived and dsDNA-derived fragments in sequencing libraries and enrichment of ssDNA-derived fragments. SSDS was used to detect meiotic DSBs in 9R/13R mice.
Project description:In order to screening the responsive miRNAs and target genes of willow under salt stress, the 30-day-old plants were exposed to the salt solution (100 mmol L-1 NaCl) for 0 h and 2 d. then RNA isolated from root and stem tissues for the same time point were mixed respectively in equal amounts for small RNA (sRNA) sequencing. sRNAs with 16–30 nt were separated from 1 µg total RNA by size fractionation. Subsequently, the selected sRNA fragments were ligated with specialized adaptors to the 5’ and 3’ ends (Illumina) using T4 RNA ligase. Then, the ligated RNAs were reverse transcribed and amplified for sequencing using Illumina Hiseq2500 (LC Sciences, Hangzhou, China). Salt stress-responsive miRNAs were identified by comparing the expression levels of miRNAs between the two libraries. Equal amounts of all 2 RNA samples were mixed together to construct one degradome library, and then sent to Hangzhou LC-Bio Co., Ltd (Hangzhou, China) for sequencing by Illumina Genome Analyzer GA-I (Illumina, San Diego, CA, USA).
Project description:Lipid intermediates derived from sphingolipid metabolism are crucial regulators of mitochondrial function from yeast to humans. Among these intermediates, trans-2-hexadecenal (t-2hex) within the sphingolipid degradation pathway exhibits remarkable efficiency in inducing mitochondria-mediated cell death. In yeast cell cultures, the addition of t-2-hex triggers complete disintegration of the mitochondrial network, leading to subsequent cell death. This effect is particularly pronounced in yeast cells lacking the activity of the t-2-hex degrading enzyme, Hfd1. However, the molecular mechanisms of t-2-hex induction of mitochondrial dysfunction are completely unknown. In this project, we want to exploit the unprecedented power of yeast genetics to unveil novel genetic determinants involved in t-2-hex's pro-apoptotic function. To accomplish this, we employed the SATAY method, which combines saturated transposon mutagenesis with high-throughput sequencing to functionally explore the yeast genome. In our screening approach, hfd1 mutant cells harboring a plasmid-encoded inducible MiniDs transposon were induced by galactose, resulting in extensive integration of the transposon throughout the yeast genome. Cells with the plasmid excised and the transposon genomically integrated were pooled together, creating a high-density transposon library comprising approximately 2.3E+06 independent insertion mutants. Subsequently, the pooled mutant library was subjected to treatment with the mitochondria-mediated death inducer, t-2-hexadecenal. As a control, cells were also incubated with the solvent dimethyl sulfoxide (DMSO), in which hexadecenal is dissolved. Following the treatments, cells were collected for genomic DNA extraction and digestion, using restriction enzymes with frequent four-base pair recognition sites. The resulting library fragments were circularized using T4 DNA ligase, and the transposon-genome junctions were selectively amplified through PCR with outward-facing primers specific to the transposon. Finally, the pooled and purified amplicons were subjected to massive sequencing on an Illumina MiSeq platform. The obtained sequences were then aligned to the reference genome of Saccharomyces cerevisiae, allowing for the mapping of transposon insertions and the calculation of transposon counts per gene. This project enabled the identification of genes required for the resistance and toxicity to t-2hex.
Project description:Serum proteomes of healthy and Leishmania-infected dogs were analyzed by DDA-MS approach to generate sample-specific spectral library for subsequent SWATH-MS analysis, namely pooled, mixed control, mixed case (Leishmania-infected), ProteoMiner enriched, and 3 SCX fractions; all containing iRT peptides for retention time normalization.
Project description:HT29-DKO cells were stably transduced with lentiCas9-Blast (Addgene, #52962) and subsequently selected using Blasticidin. Then, 300 million HT29-DKO cells that constitutively express Cas9 were transduced with lentiGuide-Puro from the Brunello library at MOI 0.3. Cells were then selected with puromycin, expanded to 3 billion cells, and then pooled together and cryofrozen in aliquots. One hundred million cells were thawed constituting over 1000× genome coverage worth of mutagenized library. The cells were infecting with PeV-A1 or PeV-A2 at an MOI of 0.1. Virus-resistant colonies were harvested. The uninfected reference used was the unselected starting population. The unselected and selected cells were both processed with QIAamp DNA columns to purify the gDNA. A first round of PCR was used to amplify the guide RNA sequences encoded in the gDNA, followed by a second round of PCR to add the barcodes/adapters for amplicon sequencing. 2% agarose gels and a QIAquick gel extraction kit were used to purify the amplicons. The amplicons were then subjected to next-generation sequencing on a HiSeq instrument lane (Illumina) via Novogene.
Project description:Huh7.5.1 cells were stably transduced with lentiCas9-Blast (Addgene, #52962) and subsequently selected using Blasticidin. Then, Huh7.5.1 cells that constitutively express Cas9 were transduced with lentiGuide-Puro from the druggable genome library at MOI 0.3. Cells were then selected with puromycin, expanded, and then pooled together and cryofrozen in aliquots. Cells were thawed constituting over 1000× genome coverage worth of mutagenized library. The cells were infecting with DENV2_429557 and DENV-2_16681_Hap1-adapted at MOI of 0.1. Virus-resistant colonies were harvested. The uninfected reference used was the unselected starting population. The unselected and selected cells were both processed with QIAamp DNA columns to purify the gDNA. A first round of PCR was used to amplify the guide RNA sequences encoded in the gDNA, followed by a second round of PCR to add the barcodes/adapters for amplicon sequencing. 2% agarose gels and a QIAquick gel extraction kit were used to purify the amplicons. The amplicons were then subjected to next-generation sequencing on a HiSeq instrument lane (Illumina) via Novogene.