Comprehensive profiling of 1015 patients' exomes reveals genomic-clinical associations in colorectal cancer.

The genetic basis of colorectal cancer (CRC) and its clinical associations remain poorly understood due to limited samples or targeted genes in current studies. Here, we perform ultradeep whole-exome sequencing on 1015 patients with CRC as part of the ChangKang Project. We identify 46 high-confident significantly mutated genes, 8 of which mutate in 14.9% of patients: LYST, DAPK1, CR2, KIF16B, NPIPB15, SYTL2, ZNF91, and KIAA0586. With an unsupervised clustering algorithm, we propose a subtyping strategy that classisfies CRC patients into four genomic subtypes with distinct clinical characteristics, including hypermutated, chromosome instability with high risk, chromosome instability with low risk, and genome stability. Analysis of immunogenicity uncover the association of immunogenicity reduction with genomic subtypes and poor prognosis in CRC. Moreover, we find that mitochondrial DNA copy number is an independent factor for predicting the survival outcome of CRCs. Overall, our results provide CRC-related molecular features for clinical practice and a valuable resource for translational research.

A Study of Cell-free DNA Fragmentation Pattern and Its Application in DNA Sample Type Classification.

Plasma cell-free DNA (cfDNA) has certain fragmentation patterns, which can bring non-random base content curves of the sequencing data's beginning cycles. We studied the patterns and found that we could determine whether a sample is cfDNA or not by just looking into the first 10 cycles of its base content curves. We analysed 3189 FastQ files, including 1442 cfDNA, 1234 genomic DNA, 507 FFPE tumour DNA and 6 urinary cfDNA. By deep analysing these data, we find the patterns are stable enough to distinguish cfDNA from other kinds of DNA samples. Based on this finding, we build classification models to recognise cfDNA samples by their sequencing data. Pattern recognition models are then trained with different classification algorithms like k-nearest neighbours (KNN), random forest and support vector machine (SVM). The result of 1000 iteration .632+ bootstrapping shows that all these classifiers can give an average accuracy higher than 98%, indicating that the cfDNA patterns are unique and can make the dataset highly separable. The best result is obtained using random forest classifier with a 99.89% average accuracy (σ = 0.00068). A tool called CfdnaPattern (http://github.com/OpenGene/CfdnaPattern) has been developed to train the model and to predict whether a sample is cfDNA or not.

Systematic Identification and Characterization of Long Non-Coding RNAs in the Silkworm, Bombyx mori.

Long noncoding RNAs (lncRNAs) are emerging as important regulators in various biological processes. However, to date, no systematic characterization of lncRNAs has been reported in the silkworm Bombyx mori. In the present study, we generated eighteen RNA-seq datasets with relatively high depth. Using an in-house designed lncRNA identification pipeline, 11,810 lncRNAs were identified for 5,556 loci. Among these lncRNAs, 474 transcripts were intronic lncRNAs (ilncRNAs), 6,250 transcripts were intergenic lncRNAs (lincRNAs), and 5,086 were natural antisense lncRNAs (lncNATs). Compared with protein-coding mRNAs, silkworm lncRNAs are shorter in terms of full length but longer in terms of exon and intron length. In addition, lncRNAs exhibit a lower level of sequence conservation, more repeat sequences overlapped and higher tissue specificity than protein-coding mRNAs in the silkworm. We found that 69 lncRNA transcripts from 33 gene loci may function as miRNA precursors, and 104 lncRNA transcripts from 72 gene loci may act as competing endogenous RNAs (ceRNAs). In total, 49.47% of all gene loci (2,749/5,556) for which lncRNAs were identified showed sex-biased expression. Co-expression network analysis resulted in 19 modules, 12 of which revealed relatively high tissue specificity. The highlighted darkgoldenrod module was specifically associated with middle and posterior silk glands, and the hub lncRNAs within this module were co-expressed with proteins involved in translation, translocation, and secretory processes, suggesting that these hub lncRNAs may function as regulators of the biosynthesis, translocation, and secretion of silk proteins. This study presents the first comprehensive genome-wide analysis of silkworm lncRNAs and provides an invaluable resource for genetic, evolutionary, and genomic studies of B. mori.

Identification and characterization of toxins in the venom gland of the Chinese bird spider, Haplopelma hainanum, by transcriptomic analysis.

Tarantula venoms provide a model system for studying toxin selectivity, structure-activity relationships and molecular evolution of peptide toxins. Previous studies have identified a large number of peptide toxins in the venom of the Chinese bird spider Haplopelma hainanum, generally regarded as a highly venomous spider. However, the lack of available RNA-seq transcriptomic and genomic data is an obstacle to understanding its venom at the molecular level. In this study, we investigated the venom gland transcriptome of H. hainanum by RNA-seq, in the absence of an available genomic sequence. We identified 201 potential toxins among 57 181 de novo assembled transcripts, including knottins, Kunitz-type toxins, enzymes and other proteins. We systematically identified most of the knottins and Kunitz-type toxins, some of which showed strongly biased expression in the venom gland, including members of the huwentoxin-1, huwentoxin-2 and magi-1 families. We also discovered several novel potential toxins. These data demonstrate the high molecular and structural diversity in the venom toxins of H. hainanum. This study offers a useful strategy for exploring the complex components of spider venoms.

Transcriptomic Analysis of the Anterior Silk Gland in the Domestic Silkworm (Bombyx mori) - Insight into the Mechanism of Silk Formation and Spinning.

Silk proteins are synthesized in the middle and posterior silk glands of silkworms, then transit into the anterior of the silk gland, where the silk fibers are produced, stored and processed. The mechanism of formation and spinning of the silk fibers has not been fully elucidated, and transcriptome analyses specific to the anterior silk gland have not been reported. In the present study, we explored gene expression profiles in five regions of silk gland samples using the RNA-Seq method. As a result, there were 959,979,570 raw reads obtained, of which 583,068,172 reads were mapped to the silkworm genome. A total of 7419 genes were found to be expressed in terms of reads per kilobase of exon model per million mapped reads ≥ 5 in at least one sample. The gene numbers and expression levels of the expressed genes differed between these regions. The differentially expressed genes were analyzed, and 282 genes were detected as up-regulated in the anterior silk gland, compared with the other parts. Functions of these genes were addressed using the gene ontology and Kyoto Encyclopedia of Genes and Genomes databases, and seven key pathways were enriched. It suggested that the ion transportation, energy metabolism, protease inhibitors and cuticle proteins played essential roles in the process of silk formation and spinning in the anterior silk gland. In addition, 210 genes were found differently expressed between males and females, which should help to elucidate the mechanism of the quality difference in silk fibers from male and female silkworms.

PC, a Novel Oral Insecticidal Toxin from Bacillus bombysepticus Involved in Host Lethality via APN and BtR-175.

Insect pests have developed resistance to chemical insecticides, insecticidal toxins as bioinsecticides or genetic protection built into crops. Consequently, novel, orally active insecticidal toxins would be valuable biological alternatives for pest control. Here, we identified a novel insecticidal toxin, parasporal crystal toxin (PC), from Bacillus bombysepticus (Bb). PC shows oral pathogenic activity and lethality towards silkworms and Cry1Ac-resistant Helicoverpa armigera strains. In vitro assays, PC after activated by trypsin binds to BmAPN4 and BtR-175 by interacting with CR7 and CR12 fragments. Additionally, trypsin-activated PC demonstrates cytotoxicity against Sf9 cells expressing BmAPN4, revealing that BmAPN4 serves as a functional receptor that participates in Bb and PC pathogenicity. In vivo assay, knocking out BtR-175 increased the resistance of silkworms to PC. These data suggest that PC is the first protein with insecticidal activity identified in Bb that is capable of causing silkworm death via receptor interactions, representing an important advance in our understanding of the toxicity of Bb and the contributions of interactions between microbial pathogens and insects to disease pathology. Furthermore, the potency of PC as an insecticidal protein makes it a good candidate for inclusion in integrated agricultural pest management systems.

Transcriptome sequencing and positive selected genes analysis of Bombyx mandarina.

The wild silkworm Bombyx mandarina is widely believed to be an ancestor of the domesticated silkworm, Bombyx mori. Silkworms are often used as a model for studying the mechanism of species domestication. Here, we performed transcriptome sequencing of the wild silkworm using an Illumina HiSeq2000 platform. We produced 100,004,078 high-quality reads and assembled them into 50,773 contigs with an N50 length of 1764 bp and a mean length of 941.62 bp. A total of 33,759 unigenes were identified, with 12,805 annotated in the Nr database, 8273 in the Pfam database, and 9093 in the Swiss-Prot database. Expression profile analysis found significant differential expression of 1308 unigenes between the middle silk gland (MSG) and posterior silk gland (PSG). Three sericin genes (sericin 1, sericin 2, and sericin 3) were expressed specifically in the MSG and three fibroin genes (fibroin-H, fibroin-L, and fibroin/P25) were expressed specifically in the PSG. In addition, 32,297 Single-nucleotide polymorphisms (SNPs) and 361 insertion-deletions (INDELs) were detected. Comparison with the domesticated silkworm p50/Dazao identified 5,295 orthologous genes, among which 400 might have experienced or to be experiencing positive selection by Ka/Ks analysis. These data and analyses presented here provide insights into silkworm domestication and an invaluable resource for wild silkworm genomics research.

Complete Genome Sequence of Bacillus bombysepticus, a Pathogen Leading to Bombyx mori Black Chest Septicemia.

Bacillus bombysepticus is a Gram-positive spore-forming bacterium. Here, we announce the first complete genome sequence of this organism isolated from the cadavers of silkworm larvae that had been sick. The genome contains a single circular chromosome and a circular plasmid. Analyses of the B. bombysepticus genome will provide insights into its pathomechanisms and biology.