Design and Engineering of Light-Induced Base Editors Facilitating Genome Editing with Enhanced Fidelity.

Base editors, which enable targeted locus nucleotide conversion in genomic DNA without double-stranded breaks, have been engineered as powerful tools for biotechnological and clinical applications. However, the application of base editors is limited by their off-target effects. Continuously expressed deaminases used for gene editing may lead to unwanted base alterations at unpredictable genomic locations. In the present study, blue-light-activated base editors (BLBEs) are engineered based on the distinct photoswitches magnets that can switch from a monomer to dimerization state in response to blue light. By fusing the N- and C-termini of split DNA deaminases with photoswitches Magnets, efficient A-to-G and C-to-T base editing is achieved in response to blue light in prokaryotic and eukaryotic cells. Furthermore, the results showed that BLBEs can realize precise blue light-induced gene editing across broad genomic loci with low off-target activity at the DNA- and RNA-level. Collectively, these findings suggest that the optogenetic utilization of base editing and optical base editors may provide powerful tools to promote the development of optogenetic genome engineering.

Genetic alteration and clonal evolution of primary glioblastoma into secondary gliosarcoma.

AIMS: Secondary gliosarcoma (SGS) rarely arises post treatment of primary glioblastoma multiforme (GBM), and contains gliomatous and sarcomatous components. The origin and clonal evolution of SGS sarcomatous components remain uncharacterized. Therapeutic radiation is mutagenic and can induce sarcomas in patients with other tumor phenotypes, but possible causal relationships between radiotherapy and induction of SGS sarcomatous components remain unexplored. Herein, we investigated the clonal origin of SGS in a patient with primary GBM progressing into SGS post-radiochemotherapy. METHODS: Somatic mutation profile in GBM and SGS was examined using whole-genome sequencing and deep-whole-exome sequencing. Mutation signatures were characterized to investigate relationships between radiochemotherapy and SGS pathogenesis. RESULTS: A mutation cluster containing two founding mutations in tumor-suppressor genes NF1 (variant allele frequency [VAF]: 50.0% in GBM and 51.1% in SGS) and TP53 (VAF: 26.7% in GBM and 50.8% in SGS) was shared in GBM and SGS. SGS exhibited an overpresented C>A (G>T) transversion (oxidative DNA damage signature) but no signature 11 mutations (alkylating-agents - exposure signature). Since radiation induces DNA lesions by generating reactive oxygen species, the mutations observed in this case of SGS were likely the result of radiotherapy rather than chemotherapy. CONCLUSIONS: Secondary gliosarcoma components likely have a monoclonal origin, and the clone possessing mutations in NF1 and TP53 was likely the founding clone in this case of SGS.

Genetic and preimplantation diagnosis of cystic kidney disease with ventriculomegaly.

Ventriculomegaly with cystic kidney disease (VMCKD) is a rare and severe disorder characterized by cerebral ventriculomegaly, greatly elevated maternal serum alpha-fetoprotein (MSAFP) or amniotic fluid alpha-fetoprotein (AFAFP) levels and kidney disease similar to Finnish congenital nephrosis. Recessive mutations in the CRB2 (NM_173689) gene have been shown to cause the syndrome. Here, we described a nonconsanguineous Chinese family with two fetuses affected with VMCKD. A novel compound heterozygous mutation was identified in the CRB2 gene with co-segregation. One mutation [c.1960G>C (p.A654P)] was inherited from the father, while another mutation [c.3078_c.3093delGGCGCGGCCCCGGCCC (p.L1026Lfs*110)] was inherited from the mother. Preimplantation genetic testing for monogenic disease (PGT-M) was performed for the carrier couple with full informed consent and successfully blocked the inheritance of the disease. Our study has important implications on molecular diagnosis and genetic counseling for VMCKD and extends the mutation spectrum in CRB2 gene.

Mechanism-Guided Design of Highly Efficient Protein Secretion and Lipid Conversion for Biomanufacturing and Biorefining.

Bacterial protein secretion represents a significant challenge in biotechnology, which is essential for the cost-effective production of therapeutics, enzymes, and other functional proteins. Here, it is demonstrated that proteomics-guided engineering of transcription, translation, secretion, and folding of ligninolytic laccase balances the process, minimizes the toxicity, and enables efficient heterologous secretion with a total protein yield of 13.7 g L-1. The secretory laccase complements the biochemical limits on lignin depolymerization well in Rhodococcus opacus PD630. Further proteomics analysis reveals the mechanisms for the oleaginous phenotype of R. opacus PD630, where a distinct multiunit fatty acid synthase I drives the carbon partition to storage lipid. The discovery guides the design of efficient lipid conversion from lignin and carbohydrate. The proteomics-guided integration of laccase-secretion and lipid production modules enables a high titer in converting lignin-enriched biorefinery waste to lipid. The fundamental mechanisms, engineering components, and design principle can empower transformative platforms for biomanufacturing and biorefining.

Two-Step Maternal-to-Zygotic Transition with Two-Phase Parental Genome Contributions.

The maternal-to-zygotic transition (MZT) is an essential developmental turning point in both plants and animals. In plants, the timing of MZT and parental contributions to the zygotic transcriptome remain unclear. Here, by overcoming technical limitations, we characterize the Arabidopsis egg cell, zygote, and embryo transcriptomes across multiple stages. Using these datasets, we demonstrate that MZT occurs during zygote development and is a two-step interrelated process of rapid maternal transcript degradation followed by large-scale de novo transcription. Parental contributions to the zygotic transcriptome are stage-dependent: the spherical zygote is characterized by a maternally dominated transcriptome, whereas the elongated zygote transcriptome shows equal parental contributions. Our results show that plant MZT is similar to that in animals, showing a typical two-step process, and that zygotic genome activation is required for zygote elongation and division, indicating that de novo transcripts are essential for the establishment of zygote polarity and embryogenesis promotion.

Hybrid sequencing reveals insight into heat sensing and signaling of bread wheat.

Wheat (Triticum aestivum L.), a globally important crop, is challenged by increasing temperatures (heat stress, HS). However its polyploid nature, the incompleteness of its genome sequences and annotation, the lack of comprehensive HS-responsive transcriptomes and the unexplored heat sensing and signaling of wheat hinder our full understanding of its adaptations to HS. The recently released genome sequences of wheat, as well as emerging single-molecular sequencing technologies, provide an opportunity to thoroughly investigate the molecular mechanisms of the wheat response to HS. We generated a high-resolution spatio-temporal transcriptome map of wheat flag leaves and filling grain under HS at 0 min, 5 min, 10 min, 30 min, 1 h and 4 h by combining full-length single-molecular sequencing and Illumina short reads sequencing. This hybrid sequencing newly discovered 4947 loci and 70 285 transcripts, generating the comprehensive and dynamic list of HS-responsive full-length transcripts and complementing the recently released wheat reference genome. Large-scale analysis revealed a global landscape of heat adaptations, uncovering unexpected rapid heat sensing and signaling, significant changes of more than half of HS-responsive genes within 30 min, heat shock factor-dependent and -independent heat signaling, and metabolic alterations in early HS-responses. Integrated analysis also demonstrated the differential responses and partitioned functions between organs and subgenomes, and suggested a differential pattern of transcriptional and alternative splicing regulation in the HS response. This study provided comprehensive data for dissecting molecular mechanisms of early HS responses in wheat and highlighted the genomic plasticity and evolutionary divergence of polyploidy wheat.

Transcriptome analysis of the digestive system of a wood-feeding termite (Coptotermes formosanus) revealed a unique mechanism for effective biomass degradation.

BACKGROUND: Wood-feeding termite, Coptotermes formosanus Shiraki, represents a highly efficient system for biomass deconstruction and utilization. However, the detailed mechanisms of lignin modification and carbohydrate degradation in this system are still largely elusive. RESULTS: In order to reveal the inherent mechanisms for efficient biomass degradation, four different organs (salivary glands, foregut, midgut, and hindgut) within a complete digestive system of a lower termite, C. formosanus, were dissected and collected. Comparative transcriptomics was carried out to analyze these organs using high-throughput RNA sequencing. A total of 71,117 unigenes were successfully assembled, and the comparative transcriptome analyses revealed significant differential distributions of GH (glycosyl hydrolase) genes and auxiliary redox enzyme genes in different digestive organs. Among the GH genes in the salivary glands, the most abundant were GH9, GH22, and GH1 genes. The corresponding enzymes may have secreted into the foregut and midgut to initiate the hydrolysis of biomass and to achieve a lignin-carbohydrate co-deconstruction system. As the most diverse GH families, GH7 and GH5 were primarily identified from the symbiotic protists in the hindgut. These enzymes could play a synergistic role with the endogenous enzymes from the host termite for biomass degradation. Moreover, twelve out of fourteen genes coding auxiliary redox enzymes from the host termite origin were induced by the feeding of lignin-rich diets. This indicated that these genes may be involved in lignin component deconstruction with its redox network during biomass pretreatment. CONCLUSION: These findings demonstrate that the termite digestive system synergized the hydrolysis and redox reactions in a programmatic process, through different parts of its gut system, to achieve a maximized utilization of carbohydrates. The detailed unique mechanisms identified from the termite digestive system may provide new insights for advanced design of future biorefinery.

Whole-genome and Transcriptome Sequencing of Prostate Cancer Identify New Genetic Alterations Driving Disease Progression.

BACKGROUND: Global disparities in prostate cancer (PCa) incidence highlight the urgent need to identify genomic abnormalities in prostate tumors in different ethnic populations including Asian men. OBJECTIVE: To systematically explore the genomic complexity and define disease-driven genetic alterations in PCa. DESIGN, SETTING, AND PARTICIPANTS: The study sequenced whole-genome and transcriptome of tumor-benign paired tissues from 65 treatment-naive Chinese PCa patients. Subsequent targeted deep sequencing of 293 PCa-relevant genes was performed in another cohort of 145 prostate tumors. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The genomic alteration landscape in PCa was analyzed using an integrated computational pipeline. Relationships with PCa progression and survival were analyzed using nonparametric test, log-rank, and multivariable Cox regression analyses. RESULTS AND LIMITATIONS: We demonstrated an association of high frequency of CHD1 deletion with a low rate of TMPRSS2-ERG fusion and relatively high percentage of mutations in androgen receptor upstream activator genes in Chinese patients. We identified five putative clustered deleted tumor suppressor genes and provided experimental and clinical evidence that PCDH9, deleted/loss in approximately 23% of tumors, functions as a novel tumor suppressor gene with prognostic potential in PCa. Furthermore, axon guidance pathway genes were frequently deregulated, including gain/amplification of PLXNA1 gene in approximately 17% of tumors. Functional and clinical data analyses showed that increased expression of PLXNA1 promoted prostate tumor growth and independently predicted prostate tumor biochemical recurrence, metastasis, and poor survival in multi-institutional cohorts of patients with PCa. A limitation of this study is that other genetic alterations were not experimentally investigated. CONCLUSIONS: There are shared and salient genetic characteristics of PCa in Chinese and Caucasian men. Novel genetic alterations in PCDH9 and PLXNA1 were associated with disease progression. PATIENT SUMMARY: We reported the first large-scale and comprehensive genomic data of prostate cancer from Asian population. Identification of these genetic alterations may help advance prostate cancer diagnosis, prognosis, and treatment.

Enhancement of Environmental Hazard Degradation in the Presence of Lignin: a Proteomics Study.

Proteomics studies of fungal systems have progressed dramatically based on the availability of more fungal genome sequences in recent years. Different proteomics strategies have been applied toward characterization of fungal proteome and revealed important gene functions and proteome dynamics. Presented here is the application of shot-gun proteomic technology to study the bio-remediation of environmental hazards by white-rot fungus. Lignin, a naturally abundant component of the plant biomass, is discovered to promote the degradation of Azo dye by white-rot fungus Irpex lacteus CD2 in the lignin/dye/fungus system. Shotgun proteomics technique was used to understand degradation mechanism at the protein level for the lignin/dye/fungus system. Our proteomics study can identify about two thousand proteins (one third of the predicted white-rot fungal proteome) in a single experiment, as one of the most powerful proteomics platforms to study the fungal system to date. The study shows a significant enrichment of oxidoreduction functional category under the dye/lignin combined treatment. An in vitro validation is performed and supports our hypothesis that the synergy of Fenton reaction and manganese peroxidase might play an important role in DR5B dye degradation. The results could guide the development of effective bioremediation strategies and efficient lignocellulosic biomass conversion.

Aberrant plasticity of peripheral sensory axons in a painful neuropathy.

Neuronal cells express considerable plasticity responding to environmental cues, in part, through subcellular mRNA regulation. Here we report on the extensive changes in distribution of mRNAs in the cell body and axon compartments of peripheral sensory neurons and the 3' untranslated region (3'UTR) landscapes after unilateral sciatic nerve entrapment (SNE) injury in rats. Neuronal cells dissociated from SNE-injured and contralateral L4 and L5 dorsal root ganglia were cultured in a compartmentalized system. Axonal and cell body RNA samples were separately subjected to high throughput RNA sequencing (RNA-Seq). The injured axons exhibited enrichment of mRNAs related to protein synthesis and nerve regeneration. Lengthening of 3'UTRs was more prevalent in the injured axons, including the newly discovered alternative cleavage and polyadenylation of NaV1.8 mRNA. Alternative polyadenylation was largely independent from the relative abundance of axonal mRNAs; but they were highly clustered in functional pathways related to RNA granule formation in the injured axons. These RNA-Seq data analyses indicate that peripheral nerve injury may result in highly selective mRNA enrichment in the affected axons with 3'UTR alterations potentially contributing to the mechanism of neuropathic pain.

Enhanced limonene production in cyanobacteria reveals photosynthesis limitations.

Terpenes are the major secondary metabolites produced by plants, and have diverse industrial applications as pharmaceuticals, fragrance, solvents, and biofuels. Cyanobacteria are equipped with efficient carbon fixation mechanism, and are ideal cell factories to produce various fuel and chemical products. Past efforts to produce terpenes in photosynthetic organisms have gained only limited success. Here we engineered the cyanobacterium Synechococcus elongatus PCC 7942 to efficiently produce limonene through modeling guided study. Computational modeling of limonene flux in response to photosynthetic output has revealed the downstream terpene synthase as a key metabolic flux-controlling node in the MEP (2-C-methyl-d-erythritol 4-phosphate) pathway-derived terpene biosynthesis. By enhancing the downstream limonene carbon sink, we achieved over 100-fold increase in limonene productivity, in contrast to the marginal increase achieved through stepwise metabolic engineering. The establishment of a strong limonene flux revealed potential synergy between photosynthate output and terpene biosynthesis, leading to enhanced carbon flux into the MEP pathway. Moreover, we show that enhanced limonene flux would lead to NADPH accumulation, and slow down photosynthesis electron flow. Fine-tuning ATP/NADPH toward terpene biosynthesis could be a key parameter to adapt photosynthesis to support biofuel/bioproduct production in cyanobacteria.

Comprehensive profiling of EBV gene expression in nasopharyngeal carcinoma through paired-end transcriptome sequencing.

The latent expression pattern of Epstein-Barr Virus (EBV) genes in nasopharyngeal carcinoma (NPC) has been extensively investigated, and the expression of several lytic genes in NPC has been reported. However, comprehensive information through EBV transcriptome analysis in NPC is limited. We performed paired-end RNA-seq to systematically and comprehensively characterize the expression of EBV genes in NPC tissue and C666-1 NPC cell line, which consistently carries EBV. In addition to the transcripts restricted to type II latency infection, the type III latency EBNA3s genes and a substantial number of lytic genes, such as BZLF1, BRLF1, and BMRF1, were detected through RNA-seq and were further verified in C666-1 cells and NPC tissue through realtime PCR.We also performed clustering analysis to classify NPC patient groups in terms of EBV gene expression, which presented two subtypes of NPC samples. Results revealed interesting patterns of EBV gene expression in NPC patients. This clustering was correlated with many signaling pathways, such as those related to heterotrimeric G-protein signaling, inflammation mediated by chemokine and cytokine signaling, ribosomes, protein metabolism, influenza infection, and ECM-receptor interaction. Our combined findings suggested that the expression of EBV genes in NPC is restricted not only to type II latency genes but also to type III latency and lytic genes. This study provided further insights into the potential role of EBV in the development of NPC.

Genomic and molecular mechanisms for efficient biodegradation of aromatic dye.

Understanding the molecular mechanisms for aromatic compound degradation is crucial for the development of effective bioremediation strategies. We report the discovery of a novel phenomenon for improved degradation of Direct Red 5B azo dye by Irpex lacteus CD2 with lignin as a co-substrate. Transcriptomics analysis was performed to elucidate the molecular mechanisms of aromatic degradation in white rot fungus by comparing dye, lignin, and dye/lignin combined treatments. A full spectrum of lignin degradation peroxidases, oxidases, radical producing enzymes, and other relevant components were up-regulated under DR5B and lignin treatments. Lignin induced genes complemented the DR5B induced genes to provide essential enzymes and redox conditions for aromatic compound degradation. The transcriptomics analysis was further verified by manganese peroxidase (MnP) protein over-expression, as revealed by proteomics, dye decolorization assay by purified MnP and increased hydroxyl radical levels, as indicated by an iron reducing activity assay. Overall, the molecular and genomic mechanisms indicated that effective aromatic polymer degradation requires synergistic enzymes and radical-mediated oxidative reactions to form an effective network of chemical processes. This study will help to guide the development of effective bioremediation and biomass degradation strategies.

Phosphorylation of trihelix transcriptional repressor ASR3 by MAP KINASE4 negatively regulates Arabidopsis immunity.

Proper control of immune-related gene expression is crucial for the host to launch an effective defense response. Perception of microbe-associated molecular patterns (MAMPs) induces rapid and profound transcriptional reprogramming via unclear mechanisms. Here, we show that ASR3 (ARABIDOPSIS SH4-RELATED3) functions as a transcriptional repressor and plays a negative role in regulating pattern-triggered immunity (PTI) in Arabidopsis thaliana. ASR3 belongs to a plant-specific trihelix transcription factor family for which functional studies are lacking. MAMP treatments induce rapid phosphorylation of ASR3 at threonine 189 via MPK4, a mitogen-activated protein kinase that negatively regulates PTI responses downstream of multiple MAMP receptors. ASR3 possesses transcriptional repressor activity via its ERF-associated amphiphilic repression motifs and negatively regulates a large subset of flg22-induced genes. Phosphorylation of ASR3 by MPK4 enhances its DNA binding activity to suppress gene expression. Importantly, the asr3 mutant shows enhanced disease resistance to virulent bacterial pathogen infection, whereas transgenic plants overexpressing the wild-type or phospho-mimetic form of ASR3 exhibit compromised PTI responses. Our studies reveal a function of the trihelix transcription factors in plant innate immunity and provide evidence that ASR3 functions as a transcriptional repressor regulated by MAMP-activated MPK4 to fine-tune plant immune gene expression.

Global gene expression profiling identifies ALDH2, CCNE1 and SMAD3 as potential prognostic markers in upper tract urothelial carcinoma.

BACKGROUND: Current knowledge about the molecular properties and prognostic markers of upper tract urothelial carcinoma (UTUC) is sparse and often based on bladder urothelial carcinoma (UC), which is thought to share common risk factors with UTUC. However, studies have suggested that differences exist regarding tumor behavior and molecular biology of these cancers, comprehensive investigations are needed to guide the clinical management of UTUC. In recent years, massively parallel sequencing has allowed insights into the biology of many cancers, and molecular prognostic markers based on this approach are rapidly emerging. The goal of this study was to characterize the gene expression patterns of UTUC using massively parallel sequencing, and identify potential molecular markers for prognosis in patients with UTUC. METHODS: We compared the genome-wide mRNA expression profile of cancer and matched normal tissues from 10 patients with UTUC to identify significantly deregulated genes. We also examined the protein levels of prognostic marker candidates in 103 patients with UTUC, and tested the association of these markers with overall survival using Kaplan-Meier model and Cox regression. RESULTS: Functional enrichment of significantly deregulated genes revealed that expression patterns of UTUC were characterized by disorders of cell proliferation and metabolism. And we also compared the expression profile of UTUC with that of bladder UC. Our results highlighted both shared (e.g. disorders of cell cycling and growth signal transduction) and tumor-specific (e.g. abnormal metabolism in UTUC and disruptions of adhesion pathways in bladder UC) features of these two cancers. Importantly, we identified that low protein expression of ALDH2 while high CCNE1 and SMAD3 were significantly associated with increased depth (*P <0.05) and lower overall survival (***P <0.0001) in an independent set of 103 patients. Multivariate Cox regression revealed that all these three genes were independent prognostic indicators in patients with UTUC (***P <0.001). CONCLUSIONS: In conclusion, our study characterized the comprehensive expression profile of UTUC and highlighted both commons and differences in expression patterns between UTUC and bladder UC. And we, for the first time, revealed that ALDH2, CCNE1 and SMAD3 are associated with prognosis in patients with UTUC.

Deep sequencing of HIV-infected cells: insights into nascent transcription and host-directed therapy.

UNLABELLED: Polyadenylated mature mRNAs are the focus of standard transcriptome analyses. However, the profiling of nascent transcripts, which often include nonpolyadenylated RNAs, can unveil novel insights into transcriptional regulation. Here, we separately sequenced total RNAs (Total RNAseq) and mRNAs (mRNAseq) from the same HIV-1-infected human CD4(+) T cells. We found that many nonpolyadenylated RNAs were differentially expressed upon HIV-1 infection, and we identified 8 times more differentially expressed genes at 12 h postinfection by Total RNAseq than by mRNAseq. These expression changes were also evident by concurrent changes in introns and were recapitulated by later mRNA changes, revealing an unexpectedly significant delay between transcriptional initiation and mature mRNA production early after HIV-1 infection. We computationally derived and validated the underlying regulatory programs, and we predicted drugs capable of reversing these HIV-1-induced expression changes followed by experimental confirmation. Our results show that combined total and mRNA transcriptome analysis is essential for fully capturing the early host response to virus infection and provide a framework for identifying candidate drugs for host-directed therapy against HIV/AIDS. IMPORTANCE: In this study, we used mass sequencing to identify genes differentially expressed in CD4(+) T cells during HIV-1 infection. To our surprise, we found many differentially expressed genes early after infection by analyzing both newly transcribed unprocessed pre-mRNAs and fully processed mRNAs, but not by analyzing mRNAs alone, indicating a significant delay between transcription initiation and mRNA production early after HIV-1 infection. These results also show that important findings could be missed by the standard practice of analyzing mRNAs alone. We then derived the regulatory mechanisms driving the observed expression changes using integrative computational analyses. Further, we predicted drugs that could reverse the observed expression changes induced by HIV-1 infection and showed that one of the predicted drugs indeed potently inhibited HIV-1 infection. This shows that it is possible to identify candidate drugs for host-directed therapy against HIV/AIDS using our genomics-based approach.

RNA sequencing reveals the complex regulatory network in the maize kernel.

RNA sequencing can simultaneously identify exonic polymorphisms and quantitate gene expression. Here we report RNA sequencing of developing maize kernels from 368 inbred lines producing 25.8 billion reads and 3.6 million single-nucleotide polymorphisms. Both the MaizeSNP50 BeadChip and the Sequenom MassArray iPLEX platforms confirm a subset of high-quality SNPs. Of these SNPs, we have mapped 931,484 to gene regions with a mean density of 40.3 SNPs per gene. The genome-wide association study identifies 16,408 expression quantitative trait loci. A two-step approach defines 95.1% of the eQTLs to a 10-kb region, and 67.7% of them include a single gene. The establishment of relationships between eQTLs and their targets reveals a large-scale gene regulatory network, which include the regulation of 31 zein and 16 key kernel genes. These results contribute to our understanding of kernel development and to the improvement of maize yield and nutritional quality.

SOAPfusion: a robust and effective computational fusion discovery tool for RNA-seq reads.

MOTIVATION: RNA-Seq provides a powerful approach to carry out ab initio investigation of fusion transcripts representing critical translocation and post-transcriptional events that recode hereditary information. Most of the existing computational fusion detection tools are challenged by the issues of accuracy and how to handle multiple mappings. RESULTS: We present a novel tool SOAPfusion for fusion discovery with paired-end RNA-Seq reads. SOAPfusion is accurate and efficient for fusion discovery with high sensitivity (≥93%), low false-positive rate (≤1.36%), even the coverage is as low as 10×, highlighting its ability to detect fusions efficiently at low sequencing cost. From real data of Universal Human Reference RNA (UHRR) samples, SOAPfusion detected 7 novel fusion genes, more than other existing tools and all genes have been validated through reverse transcription-polymerase chain reaction followed by Sanger sequencing. SOAPfusion thus proves to be an effective method with precise applicability in search of fusion transcripts, which is advantageous to accelerate pathological and therapeutic cancer studies.

Genome-wide association study dissects the genetic architecture of oil biosynthesis in maize kernels.

Maize kernel oil is a valuable source of nutrition. Here we extensively examine the genetic architecture of maize oil biosynthesis in a genome-wide association study using 1.03 million SNPs characterized in 368 maize inbred lines, including 'high-oil' lines. We identified 74 loci significantly associated with kernel oil concentration and fatty acid composition (P < 1.8 × 10(-6)), which we subsequently examined using expression quantitative trait loci (QTL) mapping, linkage mapping and coexpression analysis. More than half of the identified loci localized in mapped QTL intervals, and one-third of the candidate genes were annotated as enzymes in the oil metabolic pathway. The 26 loci associated with oil concentration could explain up to 83% of the phenotypic variation using a simple additive model. Our results provide insights into the genetic basis of oil biosynthesis in maize kernels and may facilitate marker-based breeding for oil quantity and quality.

Comprehensive analysis of RNA-Seq data reveals extensive RNA editing in a human transcriptome.

RNA editing is a post-transcriptional event that recodes hereditary information. Here we describe a comprehensive profile of the RNA editome of a male Han Chinese individual based on analysis of ∼767 million sequencing reads from poly(A)(+), poly(A)(-) and small RNA samples. We developed a computational pipeline that carefully controls for false positives while calling RNA editing events from genome and whole-transcriptome data of the same individual. We identified 22,688 RNA editing events in noncoding genes and introns, untranslated regions and coding sequences of protein-coding genes. Most changes (∼93%) converted A to I(G), consistent with known editing mechanisms based on adenosine deaminase acting on RNA (ADAR). We also found evidence of other types of nucleotide changes; however, these were validated at lower rates. We found 44 editing sites in microRNAs (miRNAs), suggesting a potential link between RNA editing and miRNA-mediated regulation. Our approach facilitates large-scale studies to profile and compare editomes across a wide range of samples.