Blue light induces neuronal-activity-regulated gene expression in the absence of optogenetic proteins, bioRxiv, 2019-03-09
Optogenetics is widely used to control diverse cellular functions with light, requiring experimenters to expose cells to bright light. Because extended exposure to visible light can be toxic to cells, it is important to characterize the effects of light stimulation on cellular function in the absence of exogenous optogenetic proteins. Here we exposed cultured mouse cortical neurons that did not express optogenetic proteins to several hours of flashing blue, red, or green light. We found that exposing neurons to as short as one hour of blue, but not red or green, light results in the induction of neuronal-activity-regulated genes without inducing neuronal activity. Our findings suggest blue light stimulation is ill-suited to long-term optogenetic experiments, especially those that measure transcription.Significance StatementOptogenetics is widely used to control cellular functions using light. In neuroscience, channelrhodopsins, exogenous light-sensitive channels, are used to achieve light-dependent control of neuronal firing. This optogenetic control of neuronal firing requires exposing neurons to high-powered light. We ask how this light exposure, in the absence of channelrhodopsin, affects the expression of neuronal-activity-regulated genes, i.e., the genes that are transcribed in response to neuronal stimuli. Surprisingly, we find that neurons without channelrhodopsin express neuronal-activity-regulated genes in response to as short as an hour of blue, but not red or green, light exposure. These findings suggest that experimenters wishing to achieve longer-term (an hour or more) optogenetic control over neuronal firing should avoid using systems that require blue light.
biorxiv neuroscience 200-500-users 2019Variation of immune cell responses in humans reveals sex-specific coordinated signaling across cell types, bioRxiv, 2019-03-09
Assessing the health and competence of the immune system is central to evaluating vaccination responses, autoimmune conditions, cancer prognosis and treatment. With an increasing number of studies examining immune dysregulation, there is a growing need for a curated reference of variation in immune parameters in healthy individuals. We used mass cytometry (CyTOF) to profile blood from 86 humans in response to 15 ex vivo immune stimuli. We present reference ranges for cell-specific immune markers and highlight differences that appear across sex and age. We identified modules of immune features that suggests there exists and underlying structure to the immune system based on signaling pathway responses across cell types. We observed increased MAPK signaling in inflammatory pathways in innate immune cells and greater overall coordination of immune cell responses in women. In contrast, men exhibited stronger STAT1 and TBK1 responses. These reference data are publicly available as a resource for immune profiling studies.
biorxiv immunology 0-100-users 2019Whole exome sequencing and characterization of coding variation in 49,960 individuals in the UK Biobank, bioRxiv, 2019-03-09
SUMMARYThe UK Biobank is a prospective study of 502,543 individuals, combining extensive phenotypic and genotypic data with streamlined access for researchers around the world. Here we describe the first tranche of large-scale exome sequence data for 49,960 study participants, revealing approximately 4 million coding variants (of which ~98.4% have frequency < 1%). The data includes 231,631 predicted loss of function variants, a >10-fold increase compared to imputed sequence for the same participants. Nearly all genes (>97%) had ≥1 predicted loss of function carrier, and most genes (>69%) had ≥10 loss of function carriers. We illustrate the power of characterizing loss of function variation in this large population through association analyses across 1,741 phenotypes. In addition to replicating a range of established associations, we discover novel loss of function variants with large effects on disease traits, including PIEZO1 on varicose veins, COL6A1 on corneal resistance, MEPE on bone density, and IQGAP2 and GMPR on blood cell traits. We further demonstrate the value of exome sequencing by surveying the prevalence of pathogenic variants of clinical significance in this population, finding that 2% of the population has a medically actionable variant. Additionally, we leverage the phenotypic data to characterize the relationship between rare BRCA1 and BRCA2 pathogenic variants and cancer risk. Exomes from the first 49,960 participants are now made accessible to the scientific community and highlight the promise offered by genomic sequencing in large-scale population-based studies.
biorxiv genomics 200-500-users 2019A rapid and simple method for assessing and representing genome sequence relatedness, bioRxiv, 2019-03-08
AbstractCoherent genomic groups are frequently used as a proxy for bacterial species delineation through computation of overall genome relatedness indices (OGRI). Average nucleotide identity (ANI) is a widely employed method for estimating relatedness between genomic sequences. However, pairwise comparisons of genome sequences based on ANI is relatively computationally intensive and therefore precludes analyses of large datasets composed of thousand genome sequences.In this work we evaluated an alternative OGRI based on k-mers counts to study prokaryotic species delimitation. A dataset containing more than 3,500 Pseudomonas genome sequences was successfully classified in few hours with the same precision as ANI. A new visualization method based on zoomable circle packing was employed for assessing relationships between among the 350 cliques generated. Amendment of databases with these Pseudomonas cliques greatly improved the classification of metagenomic read sets with k-mers-based classifier.The developed workflow was integrated in the user-friendly KI-S tool that is available at the following address <jatsext-link xmlnsxlink=httpwww.w3.org1999xlink ext-link-type=uri xlinkhref=httpsiris.angers.inra.frgalaxypub-cfbp>httpsiris.angers.inra.frgalaxypub-cfbp<jatsext-link>.
biorxiv genomics 0-100-users 2019Mapping Histone Modifications in Low Cell Number and Single Cells Using Antibody-guided Chromatin Tagmentation (ACT-seq), bioRxiv, 2019-03-08
ABSTRACTModern next-generation sequencing-based methods have empowered researchers to assay the epigenetic states of individual cells. Existing techniques for profiling epigenetic marks in single cells often require the use and optimization of time-intensive procedures such as drop fluidics, chromatin fragmentation, and end repair. Here we describe ACT-seq, a novel and streamlined method for mapping genome-wide distributions of histone tail modifications, histone variants, and chromatin-binding proteins in a small number of or single cells. ACT-seq utilizes a fusion of Tn5 transposase to Protein A that is targeted to chromatin by a specific antibody, allowing chromatin fragmentation and sequence tag insertion specifically at genomic sites presenting the relevant antigen. The Tn5 transposase enables the use of an index multiplexing strategy (iACT-seq), which enables construction of thousands of single-cell libraries in one day by a single researcher without the need for drop-based fluidics or visual sorting. We conclude that ACT-seq present an attractive alternative to existing techniques for mapping epigenetic marks in single cells.
biorxiv genomics 0-100-users 2019Noroviruses subvert the core stress granule component G3BP1 to promote viral VPg-dependent translation, bioRxiv, 2019-03-08
AbstractKnowledge of the host factors required for norovirus replication has been hindered by the challenges associated with culturing human noroviruses. We have combined proteomic analysis of the viral translation and replication complexes with a CRISPR screen, to identify host factors required for norovirus infection. The core stress granule component G3BP1 was identified as a host factor essential for efficient human and murine norovirus infection, demonstrating a conserved function across the Norovirus genus. Furthermore, we show that G3BP1 functions in the novel paradigm of viral VPg-dependent translation initiation, contributing to the assembly of translation complexes on the VPg-linked viral positive sense RNA genome by facilitating 40S recruitment. Our data suggest that G3BP1 functions by providing viral RNA a competitive advantage over capped cellular RNAs, uncovering a novel function for G3BP1 in the life cycle of positive sense RNA viruses and identifying the first host factor with pan-norovirus pro-viral activity.
biorxiv microbiology 0-100-users 2019