Displaying publications 1 - 20 of 35 in total

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  1. A comparative analysis of real-time quantitative PCR and metabarcoding methods for eDNA-based detection of the toxic dinophyte Alexandrium tamiyavanichii (Dinophyceae)
    Hii KS, Abdul Manaff AHN, Gu H, Lim PT, Leaw CP
    Mar Environ Res, 2024 Jul;199:106593.
    PMID: 38852495 DOI: 10.1016/j.marenvres.2024.106593
    The marine dinophyte Alexandrium tamiyavanichii is a toxigenic species that produces a group of neurotoxins that is responsible for paralytic shellfish poisoning in humans. Early detection of the species is essential for efficient monitoring. Harmful microalgal monitoring systems have evolved over the years with the advent of environmental DNA (eDNA)-based species detection techniques. In this study, eDNA samples were collected from a large-scale sampling covering the southern South China Sea. The sensitivity and specificity of metabarcoding of the V4 and V9 18S ribosomal DNA barcodes by high-throughput sequencing (HTS) were compared to the species-specific real-time qPCR targeting the A. tamiyavanichii ITS2 region. Environmental samples were screened for A. tamiyavanichii by qPCR (n = 43) and analyzed with metabarcoding (n = 30). Our results revealed a high occupancy profile across samples for both methods; 88% by qPCR, and 80-83% by HTS. When comparing the consistency between the two approaches, only two samples out of 30 were discordant. The V4 and V9 molecular units detected in each sample were positively correlated with the qPCR ITS2 gene copies (V4, rs = 0.67, p 
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  2. Fulltext Contaminating viral sequences in high-throughput sequencing viromics: a linkage study of 700 sequencing libraries
    Asplund M, Kjartansdóttir KR, Mollerup S, Vinner L, Fridholm H, Herrera JAR, et al.
    Clin Microbiol Infect, 2019 Oct;25(10):1277-1285.
    PMID: 31059795 DOI: 10.1016/j.cmi.2019.04.028
    OBJECTIVES: Sample preparation for high-throughput sequencing (HTS) includes treatment with various laboratory components, potentially carrying viral nucleic acids, the extent of which has not been thoroughly investigated. Our aim was to systematically examine a diverse repertoire of laboratory components used to prepare samples for HTS in order to identify contaminating viral sequences.

    METHODS: A total of 322 samples of mainly human origin were analysed using eight protocols, applying a wide variety of laboratory components. Several samples (60% of human specimens) were processed using different protocols. In total, 712 sequencing libraries were investigated for viral sequence contamination.

    RESULTS: Among sequences showing similarity to viruses, 493 were significantly associated with the use of laboratory components. Each of these viral sequences had sporadic appearance, only being identified in a subset of the samples treated with the linked laboratory component, and some were not identified in the non-template control samples. Remarkably, more than 65% of all viral sequences identified were within viral clusters linked to the use of laboratory components.

    CONCLUSIONS: We show that high prevalence of contaminating viral sequences can be expected in HTS-based virome data and provide an extensive list of novel contaminating viral sequences that can be used for evaluation of viral findings in future virome and metagenome studies. Moreover, we show that detection can be problematic due to stochastic appearance and limited non-template controls. Although the exact origin of these viral sequences requires further research, our results support laboratory-component-linked viral sequence contamination of both biological and synthetic origin.

    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  3. Fulltext A bioinformatics potpourri
    Schönbach C, Li J, Ma L, Horton P, Sjaugi MF, Ranganathan S
    BMC Genomics, 2018 01 19;19(Suppl 1):920.
    PMID: 29363432 DOI: 10.1186/s12864-017-4326-x
    The 16th International Conference on Bioinformatics (InCoB) was held at Tsinghua University, Shenzhen from September 20 to 22, 2017. The annual conference of the Asia-Pacific Bioinformatics Network featured six keynotes, two invited talks, a panel discussion on big data driven bioinformatics and precision medicine, and 66 oral presentations of accepted research articles or posters. Fifty-seven articles comprising a topic assortment of algorithms, biomolecular networks, cancer and disease informatics, drug-target interactions and drug efficacy, gene regulation and expression, imaging, immunoinformatics, metagenomics, next generation sequencing for genomics and transcriptomics, ontologies, post-translational modification, and structural bioinformatics are the subject of this editorial for the InCoB2017 supplement issues in BMC Genomics, BMC Bioinformatics, BMC Systems Biology and BMC Medical Genomics. New Delhi will be the location of InCoB2018, scheduled for September 26-28, 2018.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  4. Fulltext Biases in small RNA deep sequencing data
    Raabe CA, Tang TH, Brosius J, Rozhdestvensky TS
    Nucleic Acids Res, 2014 Feb;42(3):1414-26.
    PMID: 24198247 DOI: 10.1093/nar/gkt1021
    High-throughput RNA sequencing (RNA-seq) is considered a powerful tool for novel gene discovery and fine-tuned transcriptional profiling. The digital nature of RNA-seq is also believed to simplify meta-analysis and to reduce background noise associated with hybridization-based approaches. The development of multiplex sequencing enables efficient and economic parallel analysis of gene expression. In addition, RNA-seq is of particular value when low RNA expression or modest changes between samples are monitored. However, recent data uncovered severe bias in the sequencing of small non-protein coding RNA (small RNA-seq or sRNA-seq), such that the expression levels of some RNAs appeared to be artificially enhanced and others diminished or even undetectable. The use of different adapters and barcodes during ligation as well as complex RNA structures and modifications drastically influence cDNA synthesis efficacies and exemplify sources of bias in deep sequencing. In addition, variable specific RNA G/C-content is associated with unequal polymerase chain reaction amplification efficiencies. Given the central importance of RNA-seq to molecular biology and personalized medicine, we review recent findings that challenge small non-protein coding RNA-seq data and suggest approaches and precautions to overcome or minimize bias.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  5. Next generation sequencing yields the complete mitochondrial genome of the Zebra moray, Gymnomuraena zebra (Anguilliformes: Muraenidae)
    Loh KH, Shao KT, Chen HM, Chen CH, Chong VC, Loo PL, et al.
    Mitochondrial DNA A DNA Mapp Seq Anal, 2016 11;27(6):4230-4231.
    PMID: 26000942
    In this study, the complete mitogenome sequence of the Zebra moray, Gymnomuraena zebra (Anguilliformes: Muraenidae) has been sequenced by the next-generation sequencing method. The assembled mitogenome consisting of 16,576 bp includes 13 protein coding genes, 22 transfer RNAs, and two ribosomal RNAs genes. The overall base composition of Zebra moray is 30.2% for A, 26.8% for C, 17.2% for G, and 25.8% for T and show 80% identities to Kidako moray, Gymnothorax kidako. The complete mitogenome of the Zebra moray provides an essential and important DNA molecular data for further phylogeography and evolutionary analysis for moray eel phylogeny.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  6. Fulltext Whole-genome sequencing and analysis of the Malaysian cynomolgus macaque (Macaca fascicularis) genome
    Higashino A, Sakate R, Kameoka Y, Takahashi I, Hirata M, Tanuma R, et al.
    Genome Biol, 2012;13(7):R58.
    PMID: 22747675 DOI: 10.1186/gb-2012-13-7-r58
    The genetic background of the cynomolgus macaque (Macaca fascicularis) is made complex by the high genetic diversity, population structure, and gene introgression from the closely related rhesus macaque (Macaca mulatta). Herein we report the whole-genome sequence of a Malaysian cynomolgus macaque male with more than 40-fold coverage, which was determined using a resequencing method based on the Indian rhesus macaque genome.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  7. Genome survey and development of polymorphic microsatellite loci for Sillago sihama based on Illumina sequencing technology
    Qiu B, Fang S, Ikhwanuddin M, Wong L, Ma H
    Mol Biol Rep, 2020 Apr;47(4):3011-3017.
    PMID: 32124169 DOI: 10.1007/s11033-020-05348-z
    In this study, we first conducted a genome survey assay for Sillago sihama by Illumina sequencing platform, and then developed 15 polymorphic microsatellite loci in a wild population. A total of 129.46 Gb raw data were obtained, of which 115.07 Gb were clean data, with a sequencing depth of 179.3-folds. This genome was estimated to be 522.6 Mb in size, with the heterozygosity, repeat content and GC content being 0.63%, 21% and 44%. A total of 630,028 microsatellites were identified from the genome, of which, dinucleotide repeat was the most abundant (56.80%), followed by mononucleotide repeat (30.23%). Furthermore, 60 pairs of primers were designed and synthesized based on microsatellite sequences, of which 15 were polymorphic in a wild population. A total of 91 alleles were found, with an average of 6.07 per locus. Number of alleles, observed and expected heterozygosity per locus ranged from two to 13, from 0.250 to 0.862, and from 0.396 to 0.901, respectively. Twelve loci were highly informative (PIC > 0.5), and the others were medium informative (0.25 
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  8. Fulltext Next-Generation Biomarkers in Multiple Myeloma: Understanding the Molecular Basis for Potential Use in Diagnosis and Prognosis
    Soliman AM, Das S, Teoh SL
    Int J Mol Sci, 2021 Jul 13;22(14).
    PMID: 34299097 DOI: 10.3390/ijms22147470
    Multiple myeloma (MM) is considered to be the second most common blood malignancy and it is characterized by abnormal proliferation and an accumulation of malignant plasma cells in the bone marrow. Although the currently utilized markers in the diagnosis and assessment of MM are showing promising results, the incidence and mortality rate of the disease are still high. Therefore, exploring and developing better diagnostic or prognostic biomarkers have drawn global interest. In the present review, we highlight some of the recently reported and investigated novel biomarkers that have great potentials as diagnostic and/or prognostic tools in MM. These biomarkers include angiogenic markers, miRNAs as well as proteomic and immunological biomarkers. Moreover, we present some of the advanced methodologies that could be utilized in the early and competent diagnosis of MM. The present review also focuses on understanding the molecular concepts and pathways involved in these biomarkers in order to validate and efficiently utilize them. The present review may also help in identifying areas of improvement for better diagnosis and superior outcomes of MM.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  9. Fulltext Identification and Analysis of microRNAs in Chlorella sorokiniana Using High-Throughput Sequencing
    Azaman SNA, Satharasinghe DA, Tan SW, Nagao N, Yusoff FM, Yeap SK
    Genes (Basel), 2020 09 25;11(10).
    PMID: 32992970 DOI: 10.3390/genes11101131
    Chlorella is a popular microalga with robust physiological and biochemical characteristics, which can be cultured under various conditions. The exploration of the small RNA content of Chlorella could improve strategies for the enhancement of metabolite production from this microalga. In this study, stress was introduced to the Chlorella sorokiniana culture to produce high-value metabolites such as carotenoids and phenolic content. The small RNA transcriptome of C. sorokiniana was sequenced, focusing on microRNA (miRNA) content. From the analysis, 98 miRNAs were identified in cultures subjected to normal and stress conditions. The functional analysis result showed that the miRNA targets found were most often involved in the biosynthesis of secondary metabolites, followed by protein metabolism, cell cycle, and porphyrin and chlorophyll metabolism. Furthermore, the biosynthesis of secondary metabolites such as carotenoids, terpenoids, and lipids was found mostly in stress conditions. These results may help to improve our understanding of regulatory mechanisms of miRNA in the biological and metabolic process of Chlorella species. It is important and timely to determine the true potential of this microalga species and to support the potential for genetic engineering of microalgae as they receive increasing focus for their development as an alternative source of biofuel, food, and health supplements.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  10. Fulltext Assessment and Clinical Utility of a Non-Next-Generation Sequencing-Based Non-Invasive Prenatal Testing Technology
    Gormus U, Chaubey A, Shenoy S, Wong YW, Chan LY, Choo BP, et al.
    Curr Issues Mol Biol, 2021 Aug 17;43(2):958-964.
    PMID: 34449543 DOI: 10.3390/cimb43020068
    Background: Rolling-circle replication (RCR) is a novel technology that has not been applied to cell-free DNA (cfDNA) testing until recently. Given the cost and simplicity advantages of this technology compared to other platforms currently used in cfDNA analysis, an assessment of RCR in clinical laboratories was performed. Here, we present the first validation study from clinical laboratories utilizing RCR technology. Methods: 831 samples from spontaneously pregnant women carrying a singleton fetus, and 25 synthetic samples, were analyzed for the fetal risk of trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13), by three laboratories on three continents. All the screen-positive pregnancies were provided post-test genetic counseling and confirmatory diagnostic invasive testing (e.g., amniocentesis). The screen-negative pregnancies were routinely evaluated at birth for fetal aneuploidies, using newborn examinations, and any suspected aneuploidies would have been offered diagnostic testing or confirmed with karyotyping. Results: The study found rolling-circle replication to be a highly viable technology for the clinical assessment of fetal aneuploidies, with 100% sensitivity for T21 (95% CI: 82.35-100.00%); 100.00% sensitivity for T18 (71.51-100.00%); and 100.00% sensitivity for T13 analyses (66.37-100.00%). The specificities were >99% for each trisomy (99.7% (99.01-99.97%) for T21; 99.5% (98.62-99.85%) for T18; 99.7% (99.03-99.97%) for T13), along with a first-pass no-call rate of 0.93%. Conclusions: The study showed that using a rolling-circle replication-based cfDNA system for the evaluation of the common aneuploidies would provide greater accuracy and clinical utility compared to conventional biochemical screening, and it would provide comparable results to other reported cfDNA methodologies.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  11. Rapid detection of α-thalassaemia variants using droplet digital PCR
    Lee TY, Lai MI, Ramachandran V, Tan JA, Teh LK, Othman R, et al.
    Int J Lab Hematol, 2016 Aug;38(4):435-43.
    PMID: 27349818 DOI: 10.1111/ijlh.12520
    INTRODUCTION: Alpha thalassaemia is a highly prevalent disease globally and is a well-known public health problem in Malaysia. The deletional forms of the mutation are the most common forms found in alpha thalassaemia. The three most common deletional alpha thalassaemia found in this region include --(SEA) deletion, -α(3.7) rightward and -α(4.2) leftward deletions. The prevalence rate of triplication alpha cases such as ααα(anti3.7) and ααα(anti4.2) is not known in Malaysia although it plays a role in exacerbating the clinical phenotypes in beta thalassaemia carriers. Recently, there have been more reported cases of rare alpha thalassaemia mutations due to the advancement of molecular techniques involved in thalassaemia detections. Therefore, it is essential to develop a new method which allows the detection of different alpha thalassaemia mutations including the rare ones simultaneously and accurately.

    METHODS: The purpose of this study was to design an assay for the detection of triplications, common and rare deletional alpha thalassaemia using droplet digital PCR (ddPCR).

    RESULTS: This is a quantitative detection method to measure the changes of copy number which can detect deletions, duplications and triplications of the alpha globin gene simultaneously.

    CONCLUSION: In conclusion, ddPCR is an alternative method for rapid detection of alpha thalassaemia variants in Malaysia.

    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  12. Evaluation of Y chromosomal SNP haplogrouping in the HID-Ion AmpliSeq™ Identity Panel
    Ochiai E, Minaguchi K, Nambiar P, Kakimoto Y, Satoh F, Nakatome M, et al.
    Leg Med (Tokyo), 2016 Sep;22:58-61.
    PMID: 27591541 DOI: 10.1016/j.legalmed.2016.08.001
    The Y chromosomal haplogroup determined from single nucleotide polymorphism (SNP) combinations is a valuable genetic marker to study ancestral male lineage and ethical distribution. Next-generation sequencing has been developed for widely diverse genetics fields. For this study, we demonstrate 34 Y-SNP typing employing the Ion PGM™ system to perform haplogrouping. DNA libraries were constructed using the HID-Ion AmpliSeq™ Identity Panel. Emulsion PCR was performed, then DNA sequences were analyzed on the Ion 314 and 316 Chip Kit v2. Some difficulties became apparent during the analytic processes. No-call was reported at rs2032599 and M479 in six samples, in which the least coverage was observed at M479. A minor misreading occurred at rs2032631 and M479. A real time PCR experiment using other pairs of oligonucleotide primers showed that these events might result from the flanking sequence. Finally, Y haplogroup was determined completely for 81 unrelated males including Japanese (n=59) and Malay (n=22) subjects. The allelic divergence differed between the two populations. In comparison with the conventional Sanger method, next-generation sequencing provides a comprehensive SNP analysis with convenient procedures, but further system improvement is necessary.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  13. Fulltext De novo sequencing, assembly and analysis of eight different transcriptomes from the Malayan pangolin
    Mohamed Yusoff A, Tan TK, Hari R, Koepfli KP, Wee WY, Antunes A, et al.
    Sci Rep, 2016 09 13;6:28199.
    PMID: 27618997 DOI: 10.1038/srep28199
    Pangolins are scale-covered mammals, containing eight endangered species. Maintaining pangolins in captivity is a significant challenge, in part because little is known about their genetics. Here we provide the first large-scale sequencing of the critically endangered Manis javanica transcriptomes from eight different organs using Illumina HiSeq technology, yielding ~75 Giga bases and 89,754 unigenes. We found some unigenes involved in the insect hormone biosynthesis pathway and also 747 lipids metabolism-related unigenes that may be insightful to understand the lipid metabolism system in pangolins. Comparative analysis between M. javanica and other mammals revealed many pangolin-specific genes significantly over-represented in stress-related processes, cell proliferation and external stimulus, probably reflecting the traits and adaptations of the analyzed pregnant female M. javanica. Our study provides an invaluable resource for future functional works that may be highly relevant for the conservation of pangolins.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  14. Transcriptogenomics identification and characterization of RNA editing sites in human primary monocytes using high-depth next generation sequencing data
    Leong WM, Ripen AM, Mirsafian H, Mohamad SB, Merican AF
    Genomics, 2019 07;111(4):899-905.
    PMID: 29885984 DOI: 10.1016/j.ygeno.2018.05.019
    High-depth next generation sequencing data provide valuable insights into the number and distribution of RNA editing events. Here, we report the RNA editing events at cellular level of human primary monocyte using high-depth whole genomic and transcriptomic sequencing data. We identified over a ten thousand putative RNA editing sites and 69% of the sites were A-to-I editing sites. The sites enriched in repetitive sequences and intronic regions. High-depth sequencing datasets revealed that 90% of the canonical sites were edited at lower frequencies (<0.7). Single and multiple human monocytes and brain tissues samples were analyzed through genome sequence independent approach. The later approach was observed to identify more editing sites. Monocytes was observed to contain more C-to-U editing sites compared to brain tissues. Our results establish comparable pipeline that can address current limitations as well as demonstrate the potential for highly sensitive detection of RNA editing events in single cell type.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  15. Fulltext Population Genomics of an Anadromous Hilsa Shad Tenualosa ilisha Species across Its Diverse Migratory Habitats: Discrimination by Fine-Scale Local Adaptation
    Asaduzzaman M, Igarashi Y, Wahab MA, Nahiduzzaman M, Rahman MJ, Phillips MJ, et al.
    Genes (Basel), 2019 12 30;11(1).
    PMID: 31905942 DOI: 10.3390/genes11010046
    The migration of anadromous fish in heterogenic environments unceasingly imposes a selective pressure that results in genetic variation for local adaptation. However, discrimination of anadromous fish populations by fine-scale local adaptation is challenging because of their high rate of gene flow, highly connected divergent population, and large population size. Recent advances in next-generation sequencing (NGS) have expanded the prospects of defining the weakly structured population of anadromous fish. Therefore, we used NGS-based restriction site-associated DNA (NextRAD) techniques on 300 individuals of an anadromous Hilsa shad (Tenualosa ilisha) species, collected from nine strategic habitats, across their diverse migratory habitats, which include sea, estuary, and different freshwater rivers. The NextRAD technique successfully identified 15,453 single nucleotide polymorphism (SNP) loci. Outlier tests using the FST OutFLANK and pcadapt approaches identified 74 and 449 SNPs (49 SNPs being common), respectively, as putative adaptive loci under a divergent selection process. Our results, based on the different cluster analyses of these putatively adaptive loci, suggested that local adaptation has divided the Hilsa shad population into two genetically structured clusters, in which marine and estuarine collection sites were dominated by individuals of one genetic cluster and different riverine collection sites were dominated by individuals of another genetic cluster. The phylogenetic analysis revealed that all the riverine populations of Hilsa shad were further subdivided into the north-western riverine (turbid freshwater) and the north-eastern riverine (clear freshwater) ecotypes. Among all of the putatively adaptive loci, only 36 loci were observed to be in the coding region, and the encoded genes might be associated with important biological functions related to the local adaptation of Hilsa shad. In summary, our study provides both neutral and adaptive contexts for the observed genetic divergence of Hilsa shad and, consequently, resolves the previous inconclusive findings on their population genetic structure across their diverse migratory habitats. Moreover, the study has clearly demonstrated that NextRAD sequencing is an innovative approach to explore how dispersal and local adaptation can shape genetic divergence of non-model anadromous fish that intersect diverse migratory habitats during their life-history stages.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  16. Fulltext Complete mitochondrial genome of Dacus vijaysegarani and phylogenetic relationships with congeners and other tephritid fruit flies (Insecta: Diptera)
    Yong HS, Chua KO, Song SL, Liew YJ, Eamsobhana P, Chan KG
    Mol Biol Rep, 2021 Aug;48(8):6047-6056.
    PMID: 34357549 DOI: 10.1007/s11033-021-06608-2
    BACKGROUND: Tephritid fruit flies of the genus Dacus are members of the tribe Dacini, subfamily Dacinae. There are some 274 species worldwide, distributed in Africa and the Asia-Pacific. To date, only five complete mitochondrial genomes (mitogenomes) of Dacus fruit flies have been published and are available in the GenBank.

    METHODS AND RESULTS: In view of the lack of study on their mitogenome, we sequenced (by next generation sequencing) and annotated the complete mitogenome of D. vijaysegarani from Malaysia to determine its features and phylogenetic relationship. The whole mitogenome of D. vijaysegarani has identical gene order with the published mitogenomes of the genus Dacus, with 13 protein-coding genes, two rRNA genes, 22 tRNAs, a non-coding A + T rich control region, and intergenic spacer and overlap sequences. Phylogenetic analysis based on 15 mitochondrial genes (13 PCGs and two rRNA genes), reveals Dacus, Zeugodacus and Bactrocera forming a distinct clade. The genus Dacus forms a monophyletic group in the subclade containing also the Zeugodacus group; this Dacus-Zeugodacus subclade is distinct from the Bactrocera subclade. D. (Mellesis) vijaysegarani forms a lineage with D. (Mellesis) trimacula in the subcluster containing also the lineage of D. (Mellesis) conopsoides and D. (Callantra) longicornis. D. (Dacus) bivittatus and D. (Didacus) ciliatus form a distinct subcluster. Based on cox1 sequences, the Malaysia and Vietnam taxa of D. vijaysegarani may not be conspecific.

    CONCLUSIONS: Overall, the mitochondrial genome of D. vijaysegarani provided essential molecular data that could be useful for further studies for species diagnosis, evolution and phylogeny research of other tephritid fruit flies in the future.

    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  17. Fulltext Multi-platform discovery of haplotype-resolved structural variation in human genomes
    Chaisson MJP, Sanders AD, Zhao X, Malhotra A, Porubsky D, Rausch T, et al.
    Nat Commun, 2019 04 16;10(1):1784.
    PMID: 30992455 DOI: 10.1038/s41467-018-08148-z
    The incomplete identification of structural variants (SVs) from whole-genome sequencing data limits studies of human genetic diversity and disease association. Here, we apply a suite of long-read, short-read, strand-specific sequencing technologies, optical mapping, and variant discovery algorithms to comprehensively analyze three trios to define the full spectrum of human genetic variation in a haplotype-resolved manner. We identify 818,054 indel variants (<50 bp) and 27,622 SVs (≥50 bp) per genome. We also discover 156 inversions per genome and 58 of the inversions intersect with the critical regions of recurrent microdeletion and microduplication syndromes. Taken together, our SV callsets represent a three to sevenfold increase in SV detection compared to most standard high-throughput sequencing studies, including those from the 1000 Genomes Project. The methods and the dataset presented serve as a gold standard for the scientific community allowing us to make recommendations for maximizing structural variation sensitivity for future genome sequencing studies.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  18. Fulltext Computational approach to discriminate human and mouse sequences in patient-derived tumour xenografts
    Callari M, Batra AS, Batra RN, Sammut SJ, Greenwood W, Clifford H, et al.
    BMC Genomics, 2018 01 05;19(1):19.
    PMID: 29304755 DOI: 10.1186/s12864-017-4414-y
    BACKGROUND: Patient-Derived Tumour Xenografts (PDTXs) have emerged as the pre-clinical models that best represent clinical tumour diversity and intra-tumour heterogeneity. The molecular characterization of PDTXs using High-Throughput Sequencing (HTS) is essential; however, the presence of mouse stroma is challenging for HTS data analysis. Indeed, the high homology between the two genomes results in a proportion of mouse reads being mapped as human.

    RESULTS: In this study we generated Whole Exome Sequencing (WES), Reduced Representation Bisulfite Sequencing (RRBS) and RNA sequencing (RNA-seq) data from samples with known mixtures of mouse and human DNA or RNA and from a cohort of human breast cancers and their derived PDTXs. We show that using an In silico Combined human-mouse Reference Genome (ICRG) for alignment discriminates between human and mouse reads with up to 99.9% accuracy and decreases the number of false positive somatic mutations caused by misalignment by >99.9%. We also derived a model to estimate the human DNA content in independent PDTX samples. For RNA-seq and RRBS data analysis, the use of the ICRG allows dissecting computationally the transcriptome and methylome of human tumour cells and mouse stroma. In a direct comparison with previously reported approaches, our method showed similar or higher accuracy while requiring significantly less computing time.

    CONCLUSIONS: The computational pipeline we describe here is a valuable tool for the molecular analysis of PDTXs as well as any other mixture of DNA or RNA species.

    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
  19. Proteogenomics: From next-generation sequencing (NGS) and mass spectrometry-based proteomics to precision medicine
    Ang MY, Low TY, Lee PY, Wan Mohamad Nazarie WF, Guryev V, Jamal R
    Clin Chim Acta, 2019 Nov;498:38-46.
    PMID: 31421119 DOI: 10.1016/j.cca.2019.08.010
    One of the best-established area within multi-omics is proteogenomics, whereby the underpinning technologies are next-generation sequencing (NGS) and mass spectrometry (MS). Proteogenomics has contributed significantly to genome (re)-annotation, whereby novel coding sequences (CDS) are identified and confirmed. By incorporating in-silico translated genome variants in protein database, single amino acid variants (SAAV) and splice proteoforms can be identified and quantified at peptide level. The application of proteogenomics in cancer research potentially enables the identification of patient-specific proteoforms, as well as the association of the efficacy or resistance of cancer therapy to different mutations. Here, we discuss how NGS/TGS data are analyzed and incorporated into the proteogenomic framework. These sequence data mainly originate from whole genome sequencing (WGS), whole exome sequencing (WES) and RNA-Seq. We explain two major strategies for sequence analysis i.e., de novo assembly and reads mapping, followed by construction of customized protein databases using such data. Besides, we also elaborate on the procedures of spectrum to peptide sequence matching in proteogenomics, and the relationship between database size on the false discovery rate (FDR). Finally, we discuss the latest development in proteogenomics-assisted precision oncology and also challenges and opportunities in proteogenomics research.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods
  20. Fulltext Cognizance of Molecular Methods for the Generation of Mutagenic Phage Display Antibody Libraries for Affinity Maturation
    Lim CC, Choong YS, Lim TS
    Int J Mol Sci, 2019 Apr 15;20(8).
    PMID: 30991723 DOI: 10.3390/ijms20081861
    Antibodies leverage on their unique architecture to bind with an array of antigens. The strength of interaction has a direct relation to the affinity of the antibodies towards the antigen. In vivo affinity maturation is performed through multiple rounds of somatic hypermutation and selection in the germinal centre. This unique process involves intricate sequence rearrangements at the gene level via molecular mechanisms. The emergence of in vitro display technologies, mainly phage display and recombinant DNA technology, has helped revolutionize the way antibody improvements are being carried out in the laboratory. The adaptation of molecular approaches in vitro to replicate the in vivo processes has allowed for improvements in the way recombinant antibodies are designed and tuned. Combinatorial libraries, consisting of a myriad of possible antibodies, are capable of replicating the diversity of the natural human antibody repertoire. The isolation of target-specific antibodies with specific affinity characteristics can also be accomplished through modification of stringent protocols. Despite the ability to screen and select for high-affinity binders, some 'fine tuning' may be required to enhance antibody binding in terms of its affinity. This review will provide a brief account of phage display technology used for antibody generation followed by a summary of different combinatorial library characteristics. The review will focus on available strategies, which include molecular approaches, next generation sequencing, and in silico approaches used for antibody affinity maturation in both therapeutic and diagnostic applications.
    Matched MeSH terms: High-Throughput Nucleotide Sequencing/methods*
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