Project description:<p><em>Tripterygium wilfordii</em> is a vine used in Traditional Chinese Medicine (TCM) from the family Celastraceae. The active ingredient celastrol is a friedelane-type pentacyclic triterpenoid, with a putative role as an anti-tumor, immunosuppression, and obesity agent. Here we reported a reference genome assembly of <em>T. wilfordii</em> with high-quality annotation by using a hybrid sequencing strategy, which obtained a 340.12 Mb total genome size, a contig N50 reaching 3.09 Mb, 31593 structure genes, and the repeat percentage was 44.31%. Comparative evolutional analyses showed that <em>T. wilfordii</em> diverged from species of Malpighiales about 102.4 million years ago. In addition, we successfully anchored 91.02% sequences into 23 pseudochromosomes using Hi-C technology and the super-scaffold N50 reached 13.03 Mb. Based on integration of genome, transcriptome and metabolite analyses, as well as in vivo and in vitro enzyme assays of the two CYP450 genes, <em>TwCYP712K1</em> and <em>TwCYP712K2</em> the second biosynthesis step of celastrol was investigated and elucidated. Syntenic analysis revealed that <em>TwCYP712K1</em> and <em>TwCYP712K2</em> derived from a common ancestor. These results have provided insights into further investigating pathways for celastrol and valuable information to aid the conservation of resources and helped us reveal the evolution of Celastrales.</p>
Project description:Despite deep evolutionary conservation, recombination varies greatly across the genome, among individuals, sexes and populations and can be a major evolutionary force in the wild. Yet this variation in recombination and its impact on adaptively diverging populations is not well understood. To elucidate the nature and potential consequences of recombination rate variation, we characterized fine-scale recombination landscapes by combining pedigrees, functional genomics and field fitness measurements in an adaptively divergent pair of marine and freshwater threespine stickleback populations from River Tyne, Scotland. Through whole-genome sequencing of large nuclear families, we identified the genomic location of almost 50,000 crossovers and built recombination maps for 36 marine, freshwater, and hybrid individuals at 3.8 kilobase resolution. Using these maps, we quantified the factors driving variation in recombination rate: we find strong heterochiasmy between sexes (68% of the variation) but also differences among ecotypes (21.8%). Hybrids show evidence of significant recombination suppression, both in overall map length and in individual loci. We further tested and found reduced recombination rates both within single marine–freshwater adaptive loci and between loci on the same chromosome, suggestive of selection on linked ‘cassettes’. We tested theory supporting the evolution of linked selection using temporal sampling along a natural hybrid zone, and found that recombinants with shuffled alleles across loci show traits associated with reduced fitness. Our results support predictions that divergence in cis-acting recombination modifiers whose mechanisms are disrupted in hybrids, may have an important role to play in the maintenance of differences among adaptively diverging populations.
Project description:Despite deep evolutionary conservation, recombination varies greatly across the genome, among individuals, sexes and populations and can be a major evolutionary force in the wild. Yet this variation in recombination and its impact on adaptively diverging populations is not well understood. To elucidate the nature and potential consequences of recombination rate variation, we characterized fine-scale recombination landscapes by combining pedigrees, functional genomics and field fitness measurements in an adaptively divergent pair of marine and freshwater threespine stickleback populations from River Tyne, Scotland. Through whole-genome sequencing of large nuclear families, we identified the genomic location of almost 50,000 crossovers and built recombination maps for 36 marine, freshwater, and hybrid individuals at 3.8 kilobase resolution. Using these maps, we quantified the factors driving variation in recombination rate: we find strong heterochiasmy between sexes (68% of the variation) but also differences among ecotypes (21.8%). Hybrids show evidence of significant recombination suppression, both in overall map length and in individual loci. We further tested and found reduced recombination rates both within single marine–freshwater adaptive loci and between loci on the same chromosome, suggestive of selection on linked ‘cassettes’. We tested theory supporting the evolution of linked selection using temporal sampling along a natural hybrid zone, and found that recombinants with shuffled alleles across loci show traits associated with reduced fitness. Our results support predictions that divergence in cis-acting recombination modifiers whose mechanisms are disrupted in hybrids, may have an important role to play in the maintenance of differences among adaptively diverging populations.
Project description:Centromeres are chromosomal regions that serve as platforms for kinetochore assembly and spindle attachments, ensuring accurate chromosome segregation during cell division. Despite functional conservation, centromeric sequences are diverse and usually repetitive across species, making them challenging to assemble and identify. Here, we describe centromeres in the model oomycete Phytophthora sojae by combining long-read sequencing-based genome assembly and chromatin immunoprecipitation for the centromeric histone CENP-A followed by high-throughput sequencing (ChIP-seq). P. sojae centromeres cluster at a single focus in the nucleus at different life stages and during nuclear division. We report a highly contiguous genome assembly of the P. sojae reference strain, which enabled identification of 15 highly enriched CENP-A binding regions as putative centromeres. By focusing on 10 intact regions, we demonstrate that centromeres in P. sojae are regional, spanning 211 to 356 kb. Most of these regions are transposon-rich, poorly transcribed, and lack the euchromatin mark H3K4me2 but are embedded within regions with the heterochromatin marks H3K9me3 and H3K27me3.
Project description:More than 2x10E9 sequences made on Illumina platform derived from the genome of E14 embryonic stem cells cultured in our laboratory were used to build a database of about 2.7x10E6 single nucleotide variant. The database was validated using other two sequencing datasets from other laboratory and high overlap was observed. The identified variant are enriched on intergenic regions, but several thousands reside on gene exons and regulatory regions, such as promoters, enhancers, splicing site and untranslated regions of RNA, thus indicating high probability of an important functional impact on the molecular biology of this cells. We created a new E14 genome assembly including the new identified variants and used it to map reads from next generation sequencing data generated in our laboratory or in others on E14 cell line. We observed an increase in the number of mapped reads of about 5%. CpG dinucleotide showed the higher variation frequency, probably because of it could be target of DNA methylation. We performed a reduced representation bisulfite sequencing on E14 cell line to test our new genome assembly with respect to the mm9 genome reference. After mapping and methylation status calling, we obtained an increase of about 120,000 called CpG and we avoided about 20,000 wrong CpG calling. genotyping of E14 embryonic stem cells (ESCs) and Reduced representation Bisulfite Sequencing (RRBS) of E14 ESCs.
Project description:The effect of different diets (i.e. fish oil based vs vegetable oil based) on liver transcription profiles over the life history stages (freshwater and marine phases) of cultured Atlantic salmon (Salmo salar) were explored. Two groups of fish were raised from first feeding on different lipid containing diets; a) the standard 100% fish oil based diet, the other enriched with a blend of vegetable oils (75%) + fish oil (25%). Liver samples were taken from fish at four time points: two freshwater phase (as parr 36 weeks post hatch (wph); as pre-smolts, 52 wph) and two marine phase ( as post-smolts 55 wph; and as adult fish , 86 wph). A total of 96 cDNA microarray hybridisations - TRAITS / SGP Atlantic salmon 17k feature cDNA microarray - were performed ( 2 diets x 4 time points x 6 biological replicates x 2 -dye swap) using a comon pooled reference contol design.
Project description:We have sequenced a wild Prunus mume and constructed a reference sequence for this genome. In order to improve quality of gene models, RNA samples of five tissues (bud, leaf, root, stem, fruit) were extracted from the Prunus mume. To investigate tissue specific expression using the reference genome assembly and annotated genes, we extracted RNA samples of different tissues and conducted transcriptome sequencing and DEG analysis.