Publications by authors named "Jaswinder Khattra"

We evaluated the Xpert MTB/Rif Ultra assay performance for (MTB) detection in formalin-fixed paraffin-embedded tissue (FFPET) compared to mycobacterial culture or laboratory-developed MTB PCR test (LDT). FFPET samples with histological features suggestive of tuberculosis from 2018 to 2023 were selected. Five hundred microlitres of tissue lysis buffer was added to FFPET scrolls and incubated at 75 °C for 5 min.

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We introduce a target capture next-generation sequencing methodology, the ONETest Coronaviruses Plus, to sequence the SARS-CoV-2 genome and select loci of other respiratory viruses. We applied the ONETest on 70 respiratory samples (collected in Florida, USA between May and July, 2020), in which SARS-CoV-2 had been detected by a PCR assay. For 48 of the samples, we also applied the ARTIC protocol.

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The advent of next generation sequencing has vastly improved the resolution of mutation detection, thereby both increasing the resolution of the analysis of cancer tissues and shining light on the existence of somatic driver mutations in normal tissues, even in the absence of cancer. Studies have described somatic driver mutations in normal skin, blood, peritoneal washings, and esophageal epithelium. Such findings prompt speculation on whether such mutations exist in other tissues, such as the eutopic endometrium in particular, due to the highly regenerative nature of the endometrium and the recent observation of recurrent somatic driver mutations in deep infiltrating and iatrogenic endometriosis (tissues believed to be derived from the eutopic endometrium) by our group and others.

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We performed phylogenetic analysis of high-grade serous ovarian cancers (68 samples from seven patients), identifying constituent clones and quantifying their relative abundances at multiple intraperitoneal sites. Through whole-genome and single-nucleus sequencing, we identified evolutionary features including mutation loss, convergence of the structural genome and temporal activation of mutational processes that patterned clonal progression. We then determined the precise clonal mixtures comprising each tumor sample.

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Human cancers, including breast cancers, comprise clones differing in mutation content. Clones evolve dynamically in space and time following principles of Darwinian evolution, underpinning important emergent features such as drug resistance and metastasis. Human breast cancer xenoengraftment is used as a means of capturing and studying tumour biology, and breast tumour xenografts are generally assumed to be reasonable models of the originating tumours.

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The evolution of cancer genomes within a single tumor creates mixed cell populations with divergent somatic mutational landscapes. Inference of tumor subpopulations has been disproportionately focused on the assessment of somatic point mutations, whereas computational methods targeting evolutionary dynamics of copy number alterations (CNA) and loss of heterozygosity (LOH) in whole-genome sequencing data remain underdeveloped. We present a novel probabilistic model, TITAN, to infer CNA and LOH events while accounting for mixtures of cell populations, thereby estimating the proportion of cells harboring each event.

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We introduce PyClone, a statistical model for inference of clonal population structures in cancers. PyClone is a Bayesian clustering method for grouping sets of deeply sequenced somatic mutations into putative clonal clusters while estimating their cellular prevalences and accounting for allelic imbalances introduced by segmental copy-number changes and normal-cell contamination. Single-cell sequencing validation demonstrates PyClone's accuracy.

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Primary triple-negative breast cancers (TNBCs), a tumour type defined by lack of oestrogen receptor, progesterone receptor and ERBB2 gene amplification, represent approximately 16% of all breast cancers. Here we show in 104 TNBC cases that at the time of diagnosis these cancers exhibit a wide and continuous spectrum of genomic evolution, with some having only a handful of coding somatic aberrations in a few pathways, whereas others contain hundreds of coding somatic mutations. High-throughput RNA sequencing (RNA-seq) revealed that only approximately 36% of mutations are expressed.

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Recent advances in next generation sequencing have made it possible to precisely characterize all somatic coding mutations that occur during the development and progression of individual cancers. Here we used these approaches to sequence the genomes (>43-fold coverage) and transcriptomes of an oestrogen-receptor-alpha-positive metastatic lobular breast cancer at depth. We found 32 somatic non-synonymous coding mutations present in the metastasis, and measured the frequency of these somatic mutations in DNA from the primary tumour of the same patient, which arose 9 years earlier.

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A crucial step in the development of muscle cells in all metazoan animals is the assembly and anchorage of the sarcomere, the essential repeat unit responsible for muscle contraction. In Caenorhabditis elegans, many of the critical proteins involved in this process have been uncovered through mutational screens focusing on uncoordinated movement and embryonic arrest phenotypes. We propose that additional sarcomeric proteins exist for which there is a less severe, or entirely different, mutant phenotype produced in their absence.

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Background: Granulosa-cell tumors (GCTs) are the most common type of malignant ovarian sex cord-stromal tumor (SCST). The pathogenesis of these tumors is unknown. Moreover, their histopathological diagnosis can be challenging, and there is no curative treatment beyond surgery.

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Starting with SAGE-libraries prepared from C. elegans FAC-sorted embryonic intestine cells (8E-16E cell stage), from total embryos and from purified oocytes, and taking advantage of the NextDB in situ hybridization data base, we define sets of genes highly expressed from the zygotic genome, and expressed either exclusively or preferentially in the embryonic intestine or in the intestine of newly hatched larvae; we had previously defined a similarly expressed set of genes from the adult intestine. We show that an extended TGATAA-like sequence is essentially the only candidate for a cis-acting regulatory motif common to intestine genes expressed at all stages.

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To facilitate discovery of novel human embryonic stem cell (ESC) transcripts, we generated 2.5 million LongSAGE tags from 9 human ESC lines. Analysis of this data revealed that ESCs express proportionately more RNA binding proteins compared with terminally differentiated cells, and identified novel ESC transcripts, at least one of which may represent a marker of the pluripotent state.

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Transcriptome profiling offers a powerful approach to investigating developmental processes. Long serial analysis of gene expression (LongSAGE) is particularly attractive for this purpose because of its inherent quantitative features and independence of both hybridization variables and prior knowledge of transcript identity. Here, we describe the validation and initial application of a modified protocol for amplifying cDNA preparations from <10 ng of RNA (<10(3) cells) to allow representative LongSAGE libraries to be constructed from rare stem cell-enriched populations.

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Background: The recent availability of genome sequences of multiple related Caenorhabditis species has made it possible to identify, using comparative genomics, similarly transcribed genes in Caenorhabditis elegans and its sister species. Taking this approach, we have identified numerous novel ciliary genes in C. elegans, some of which may be orthologs of unidentified human ciliopathy genes.

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We describe the details of a serial analysis of gene expression (SAGE) library construction and analysis platform that has enabled the generation of >298 high-quality SAGE libraries and >30 million SAGE tags primarily from sub-microgram amounts of total RNA purified from samples acquired by microdissection. Several RNA isolation methods were used to handle the diversity of samples processed, and various measures were applied to minimize ditag PCR carryover contamination. Modifications in the SAGE protocol resulted in improved cloning and DNA sequencing efficiencies.

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A SAGE library was prepared from hand-dissected intestines from adult Caenorhabditis elegans, allowing the identification of >4000 intestinally-expressed genes; this gene inventory provides fundamental information for understanding intestine function, structure and development. Intestinally-expressed genes fall into two broad classes: widely-expressed "housekeeping" genes and genes that are either intestine-specific or significantly intestine-enriched. Within this latter class of genes, we identified a subset of highly-expressed highly-validated genes that are expressed either exclusively or primarily in the intestine.

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Currently, little information is available regarding the molecular organization of integrated transgenes in genetically-engineered fish. We performed a detailed structural analysis of an inserted transgene in one strain (M77) of transgenic coho salmon (Oncorhynchus kisutch) containing a salmon growth hormone gene construct (OnMTGH1). Microinjected DNA was found to have inserted into a single site in the coho salmon genome, and was organized with four complete internal copies and two partial terminal copies of the OnMTGH1 construct.

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We analyzed 8.55 million LongSAGE tags generated from 72 libraries. Each LongSAGE library was prepared from a different mouse tissue.

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Cilia and flagella play important roles in many physiological processes, including cell and fluid movement, sensory perception, and development. The biogenesis and maintenance of cilia depend on intraflagellar transport (IFT), a motility process that operates bidirectionally along the ciliary axoneme. Disruption in IFT and cilia function causes several human disorders, including polycystic kidneys, retinal dystrophy, neurosensory impairment, and Bardet-Biedl syndrome (BBS).

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We have identified longevity-associated genes in a long-lived Caenorhabditis elegans daf-2 (insulin/IGF receptor) mutant using serial analysis of gene expression (SAGE), a method that efficiently quantifies large numbers of mRNA transcripts by sequencing short tags. Reduction of daf-2 signaling in these mutant worms leads to a doubling in mean lifespan. We prepared C.

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Rhodococcus sp. strain RHA1, a potent polychlorinated-biphenyl (PCB)-degrading strain, contains three linear plasmids ranging in size from 330 to 1,100 kb. As part of a genome sequencing project, we report here the complete sequence and characterization of the smallest and least-well-characterized of the RHA1 plasmids, pRHL3.

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We sequenced the 29,751-base genome of the severe acute respiratory syndrome (SARS)-associated coronavirus known as the Tor2 isolate. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses, including two human coronaviruses, HCoV-OC43 and HCoV-229E. Phylogenetic analysis of the predicted viral proteins indicates that the virus does not closely resemble any of the three previously known groups of coronaviruses.

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