Transmission dynamics and control of multidrug-resistant < i > Klebsiella pneumoniae < /i > in neonates in a developing country
Multidrug-resistantKlebsiella pneumoniae is an increasing cause of infant mortality in developing countries. We aimed to develop a quantitative understanding of the drivers of this epidemic by estimating the effects of antibiotics on nosocomial transmission risk, comparing competing hypotheses about mechanisms of spread, and quantifying the impact of potential interventions. Using a sequence of dynamic models, we analysed data from a one-year prospective carriage study in a Cambodian neonatal unit with hyperendemic third-generation cephalosporin-resistantK. pneumoniae. All widely-used antibiotics except imipenem were assoc...
Source: eLife - December 3, 2019 Category: Biomedical Science Tags: Epidemiology and Global Health Microbiology and Infectious Disease Source Type: research

Analysis of stochastic fluctuations in responsiveness is a critical step toward personalized anesthesia
Traditionally, drug dosing is based on a concentration-response relationship estimated in a population. Yet, in specific individuals, decisions based on the population-level effects frequently result in over or under-dosing. Here, we interrogate the relationship between population-based and individual-based responses to anesthetics in mice and zebrafish. The anesthetic state was assessed by quantifying responses to simple stimuli. Individual responses dynamically fluctuated at a fixed drug concentration. These fluctuations exhibited resistance to state transitions. Drug sensitivity varied dramatically across individuals in...
Source: eLife - December 3, 2019 Category: Biomedical Science Tags: Neuroscience Physics of Living Systems Source Type: research

Coordination of tissue cell polarity by auxin transport and signaling
Plants coordinate the polarity of hundreds of cells during vein formation, but how they do so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of membrane trafficking, positions PIN-FORMED auxin transporters to the correct side of the plasma membrane; the resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and induce vein formation. Contrary to predictions of the hypothesis, we find that vein formation occurs in the absence of PIN-FORMED or any other intercellular auxin-transporter; that the residual auxin-transport-independent vein-patterning activity relies on auxin...
Source: eLife - December 3, 2019 Category: Biomedical Science Tags: Developmental Biology Plant Biology Source Type: research

Cycling in synchrony
The corn smut fungus uses two different mechanisms to control its cell cycle when it is infecting plants. (Source: eLife)
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Developmental Biology Microbiology and Infectious Disease Source Type: research

Coronary arterial development is regulated by a Dll4-Jag1-EphrinB2 signaling cascade
Coronaries are essential for myocardial growth and heart function. Notch is crucial for mouse embryonic angiogenesis, but its role in coronary development remains uncertain. We show Jag1, Dll4 and activated Notch1 receptor expression in sinus venosus (SV) endocardium. EndocardialJag1 removal blocks SV capillary sprouting, whileDll4 inactivation stimulates excessive capillary growth, suggesting that ligand antagonism regulates coronary primary plexus formation. Later endothelial ligand removal, or forced expression of Dll4 or the glycosyltransferase Mfng, blocks coronary plexus remodeling, arterial differentiation, and peri...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Herpesviral lytic gene functions render the viral genome susceptible to novel editing by CRISPR/Cas9
Herpes simplex virus (HSV) establishes lifelong latent infection and can cause serious human disease, but current antiviral therapies target lytic but not latent infection. We screened for sgRNAs that cleave HSV-1 DNA sequences efficientlyin vitro and used these sgRNAs to observe the first editing of quiescent HSV-1 DNA. The sgRNAs targeted lytic replicating viral DNA genomes more efficiently than quiescent genomes, consistent with the open structure of lytic chromatin. Editing of latent genomes caused short indels while editing of replicating genomes produced indels, linear molecules and large genomic sequence loss around...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Genetics and Genomics Microbiology and Infectious Disease Source Type: research

The MADS-box transcription factor PHERES1 controls imprinting in the endosperm by binding to domesticated transposons
MADS-box transcription factors (TFs) are ubiquitous in eukaryotic organisms and play major roles during plant development. Nevertheless, their function in seed development remains largely unknown. Here we show that the imprintedArabidopsis thaliana MADS-box TF PHERES1 (PHE1) is a master regulator of paternally expressed imprinted genes, as well as of non-imprinted key regulators of endosperm development. PHE1 binding sites show distinct epigenetic modifications on maternal and paternal alleles, correlating with parental-specific transcriptional activity. Importantly, we show that the CArG-box-like DNA-binding motifs bound ...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Genetics and Genomics Plant Biology Source Type: research

Modulating FOXO3 transcriptional activity by small, DBD-binding molecules
FOXO transcription factors are critical regulators of cell homeostasis and steer cell death, differentiation and longevity in mammalian cells. By combined pharmacophore-modelling-basedin silico and fluorescence polarization-based screening we identified small molecules that physically interact with the DNA-binding domain (DBD) of FOXO3 and modulate the FOXO3 transcriptional program in human cells. The mode of interaction between compounds and the FOXO3-DBD was assessedvia NMR spectroscopy and docking studies. We demonstrate that compounds S9 and its oxalate salt S9OX interfere with FOXO3 target promoter binding, gene trans...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Structural Biology and Molecular Biophysics Source Type: research

Neurotrophins induce fission of mitochondria along embryonic sensory axons
We report that neurotrophins induce the fission of mitochondria along embryonic chick sensory axons driven by combined PI3K and Mek-Erk signaling. Following an initial burst of fission, a new steady state of neurotrophin-dependent mitochondria length is established. Mek-Erk controls the activity of the fission mediator Drp1 GTPase, while PI3K may contribute to the actin-dependent aspect of fission. Drp1-mediated fission is required for nerve growth factor (NGF)-induced collateral branching in vitro and expression of dominant negative Drp1 impairs the branching of axons in the developing spinal cord in vivo. Fission is also...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Cell Biology Neuroscience Source Type: research

An mRNA-binding channel in the ES6S region of the translation 48S-PIC promotes RNA unwinding and scanning
Loading of mRNA onto the ribosomal 43S pre-initiation complex (PIC) and its subsequent scanning require the removal of the secondary structure of the by RNA helicases such as eIF4A. However, the topology and mechanics of the scanning complex bound to mRNA (48S-PIC) and the influence of its solvent-side composition on the scanning process are poorly known. Here, we found that the ES6S region of the 48S-PIC constitutes an extended binding channel for eIF4A-mediated unwinding of mRNA and scanning. Blocking ES6S inhibited the cap-dependent translation of mRNAs that have structured 5 ′ UTRs (including G-quadruplexes), man...
Source: eLife - December 2, 2019 Category: Biomedical Science Tags: Chromosomes and Gene Expression Source Type: research

Causal links between parietal alpha activity and spatial auditory attention
Both visual and auditory spatial selective attention result in lateralized alpha (8-14 Hz) oscillatory power in parietal cortex: alpha increases in the hemisphere ipsilateral to attentional focus. Brain stimulation studies suggest a causal relationship between parietal alpha and suppression of the representation of contralateral visual space. However, there is no evidence that parietal alpha controls auditory spatial attention. Here, we performed high definition transcranial alternating current stimulation (HD-tACS) on human subjects performing an auditory task in which they directed attention based on either spatial or no...
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Alpha/beta power decreases track the fidelity of stimulus-specific information
Massed synchronised neuronal firing is detrimental to information processing. When networks of task-irrelevant neurons fire in unison, they mask the signal generated by task-critical neurons. On a macroscopic level, such synchronisation can contribute to alpha/beta (8-30Hz) oscillations. Reducing the amplitude of these oscillations, therefore, may enhance information processing. Here, we test this hypothesis. Twenty-one participants completed an associative memory task while undergoing simultaneous EEG-fMRI recordings. Using representational similarity analysis, we quantified the amount of stimulus-specific information rep...
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Characterizing causality in cancer
Philosophers have explored the concept of causality for centuries. Here we argue that ideas about causality from philosophy can help scientists to better understand how cancerous tumors grow and spread in the body. After outlining six characteristics of causality that are relevant to cancer, we emphasize the importance of feedback loops and interactions between tumor-cell-intrinsic and tumor-cell-extrinsic factors for explaining the formation and dissemination of tumors. (Source: eLife)
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Cancer Biology Source Type: research

Mechanisms of hyperexcitability in Alzheimer's disease hiPSC-derived neurons and cerebral organoids vs. isogenic control
Human Alzheimer's disease (AD) brains and transgenic AD mouse models manifest hyperexcitability. This aberrant electrical activity is caused by synaptic dysfunction that represents the major pathophysiological correlate of cognitive decline. However, the underlying mechanism for this excessive excitability remains incompletely understood. To investigate the basis for the hyperactivity, we performed electrophysiological and immunofluorescence studies on hiPSC-derived cerebrocortical neuronal cultures and cerebral organoids bearing AD-related mutations in presenilin 1 or amyloid precursor protein vs. isogenic gene corrected ...
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Endothelial EphB4 maintains vascular integrity and transport function in adult heart
The homeostasis of heart and other organs relies on the appropriate provision of nutrients and functional specialization of the local vasculature. Here, we have used mouse genetics, imaging and cell biology approaches to investigate how homeostasis in the adult heart is controlled by endothelial EphB4 and its ligand ephrin-B2, which are known regulators of vascular morphogenesis and arteriovenous differentiation during development. We show that inducible and endothelial cell-specific inactivation ofEphb4 in adult mice is compatible with survival, but leads to rupturing of cardiac capillaries, cardiomyocyte hypertrophy, and...
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Developmental Biology Source Type: research

Bringing on the itch
Neutrophils are the first immune cells that enter the skin and cause itch in atopic dermatitis. (Source: eLife)
Source: eLife - November 29, 2019 Category: Biomedical Science Tags: Immunology and Inflammation Neuroscience Source Type: research

Specific lid-base contacts in the 26S proteasome control the conformational switching required for substrate degradation
The 26S proteasome is essential for proteostasis and the regulation of vital processes through ATP-dependent degradation of ubiquitinated substrates. To accomplish the multi-step degradation process, the proteasome's regulatory particle, consisting of lid and base subcomplexes, undergoes major conformational changes whose origin is unknown. Investigating theSaccharomyces cerevisiae proteasome, we found that peripheral interactions between the lid subunit Rpn5 and the base AAA+-ATPase ring are important for stabilizing the substrate-engagement-competent state and coordinating the conformational switch to processing states u...
Source: eLife - November 28, 2019 Category: Biomedical Science Tags: Biochemistry and Chemical Biology Source Type: research

Micronuclei-based model system reveals functional consequences of chromothripsis in human cells
Cancer cells often harbor chromosomes in abnormal numbers and with aberrant structure. The consequences of these chromosomal aberrations are difficult to study in cancer, and therefore several model systems have been developed in recent years. We show that human cells with extra chromosome engineered via microcell-mediated chromosome transfer often gain massive chromosomal rearrangements. The rearrangements arose by chromosome shattering and rejoining as well as by replication-dependent mechanisms. We show that the isolated micronuclei lack functional lamin B1 and become prone to envelope rupture, which leads to DNA damage...
Source: eLife - November 28, 2019 Category: Biomedical Science Tags: Cell Biology Genetics and Genomics Source Type: research

Real time dynamics of gating-related conformational changes in CorA
CorA, a divalent-selective channel in the metal ion transport superfamily, is the major Mg2+-influx pathway in prokaryotes. CorA structures in closed (Mg2+-bound), and open (Mg2+-free) states, together with functional data showed that Mg2+-influx inhibits further Mg2+-uptake completing a regulatory feedback loop. While the closed state structure is a symmetric pentamer, the open state displayed unexpected asymmetric architectures. Using high-speed atomic force microscopy (HS-AFM), we explored the Mg2+-dependent gating transition of single CorA channels: HS-AFM movies during Mg2+-depletion experiments revealed the channel's...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

An N-terminal motif in NLR immune receptors is functionally conserved across distantly related plant species
The molecular codes underpinning the functions of plant NLR immune receptors are poorly understood. We usedin vitro Mu transposition to generate a random truncation library and identify the minimal functional region of NLRs. We applied this method to NRC4 —a helper NLR that functions with multiple sensor NLRs within a Solanaceae receptor network. This revealed that the NRC4 N-terminal 29 amino acids are sufficient to induce hypersensitive cell death. This region is defined by the consensus MADAxVSFxVxKLxxLLxxEx (MADA motif) that is conserved at the N-termini of NRC family proteins and ~20% of coiled-coil (CC)-type pl...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Plant Biology Source Type: research

The role of premature evidence accumulation in making difficult perceptual decisions under temporal uncertainty
The computations and neural processes underpinning decision making have primarily been investigated using highly simplified tasks in which stimulus onsets cue observers to start accumulating choice-relevant information. Yet, in daily life we are rarely afforded the luxury of knowing precisely when choice-relevant information will appear. Here, we examined neural indices of decision formation while subjects discriminated subtle stimulus feature changes whose timing relative to stimulus onset ('foreperiod') was uncertain. Joint analysis of behavioural error patterns and neural decision signal dynamics indicated that subjects...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Kv1.1 contributes to a rapid homeostatic plasticity of intrinsic excitability in CA1 pyramidal neurons in vivo
In area CA1 of the hippocampus, the selection of place cells to represent a new environment is biased towards neurons with higher excitability. However, different environments are represented by orthogonal cell ensembles, suggesting that regulatory mechanisms exist. Activity-dependent plasticity of intrinsic excitability, as observed in vitro, is an attractive candidate. Here, using whole-cell patch-clamp recordings of CA1 pyramidal neurons in anesthetized rats, we have examined how inducing theta-bursts of action potentials affects their intrinsic excitability over time. We observed a long-lasting, homeostatic depression ...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Kinetics of cytokine receptor trafficking determine signaling and functional selectivity
Cytokines activate signaling via assembly of cell surface receptors, but it is unclear whether modulation of cytokine-receptor binding parameters can modify biological outcomes. We have engineered IL-6 variants with different affinities to gp130 to investigate how cytokine receptor binding dwell-times influence functional selectivity. Engineered IL-6 variants showed a range of signaling amplitudes and induced biased signaling, with changes in receptor binding dwell-times affecting more profoundly STAT1 than STAT3 phosphorylation. We show that this differential signaling arises from defective translocation of ligand-gp130 c...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Immunology and Inflammation Source Type: research

Helix breaking transition in the S4 of HCN channel is critical for hyperpolarization-dependent gating
In contrast to most voltage-gated ion channels, hyperpolarization- and cAMP gated (HCN) ion channels open on hyperpolarization. Structure-function studies show that the voltage-sensor of HCN channels are unique but the mechanisms that determine gating polarity remain poorly understood. All-atom molecular dynamics simulations (~20 ms) of HCN1 channel under hyperpolarization reveals an initial downward movement of the S4 voltage-sensor but following the transfer of last gating charge, the S4 breaks into two sub-helices with the lower sub-helix becoming parallel to the membrane. Functional studies on bipolar channels show tha...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

The < i > Wolbachia < /i > cytoplasmic incompatibility enzyme CidB targets nuclear import and protamine-histone exchange factors
IntracellularWolbachia bacteria manipulate arthropod reproduction to promote their own inheritance. The most prevalent mechanism, cytoplasmic incompatibility (CI), traces to aWolbachia deubiquitylase, CidB, and CidA. CidB has properties of a toxin, while CidA binds CidB and rescues embryonic viability. CidB is also toxic to yeast where we identified both host effects and high-copy suppressors of toxicity. The strongest suppressor was karyopherin- α, a nuclear-import receptor; this required nuclear localization-signal binding. A protein-interaction screen ofDrosophila extracts using a substrate-trapping catalytic muta...
Source: eLife - November 27, 2019 Category: Biomedical Science Tags: Developmental Biology Microbiology and Infectious Disease Source Type: research

The HCN domain couples voltage gating and cAMP response in Hyperpolarization-activated Cyclic Nucleotide-gated channels
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control spontaneous electrical activity in heart and brain. Binding of cAMP to the cyclic nucleotide-binding domain (CNBD) facilitates channel opening by relieving a tonic inhibition exerted by the CNBD. Despite high resolution structures of the HCN1 channel in the cAMP bound and unbound states, the structural mechanism coupling ligand binding to channel gating is unknown. Here we show that the recently identified helical HCN-domain (HCND) mechanically couples the CNBD and channel voltage sensing domain (VSD), possibly acting as a sliding crank that convert...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Punishment insensitivity emerges from impaired contingency detection, not aversion insensitivity or reward dominance
We examined these hypotheses by applying several analysis strategies to the behaviour of rats (n = 48; 18 female) trained in a conditioned punishment task that permitted concurrent assessment of punishment, reward-seeking, and Pavlovian fear. We show that punishment insensitivity is a unique phenotype, unrelated to differences in reward-seeking and Pavlovian fear, and due to a failure of instrumental control. Subjects insensitive to punishment are afraid of aversive events, they are simply unable to change their behaviour to avoid them. (Source: eLife)
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Ten simple rules for the computational modeling of behavioral data
Computational modeling of behavior has revolutionized psychology and neuroscience. By fitting models to experimental data we can probe the algorithms underlying behavior, find neural correlates of computational variables and better understand the effects of drugs, illness and interventions. But with great power comes great responsibility. Here, we offer ten simple rules to ensure that computational modeling is used with care and yields meaningful insights. In particular, we present a beginner-friendly, pragmatic and details-oriented introduction on how to relate models to data. What, exactly, can a model tell us about the ...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Elements of a stochastic 3D prediction engine in larval zebrafish prey capture
The computational principles underlying predictive capabilities in animals are poorly understood. Here, we wondered whether predictive models mediating prey capture could be reduced to a simple set of sensorimotor rules performed by a primitive organism. For this task, we chose the larval zebrafish, a tractable vertebrate that pursues and captures swimming microbes. Using a novel naturalistic 3D setup, we show that the zebrafish combines position and velocity perception to construct a future positional estimate of its prey, indicating an ability to project trajectories forward in time. Importantly, the stochasticity in the...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Neuroscience Physics of Living Systems Source Type: research

Design of biochemical pattern forming systems from minimal motifs
Although molecular self-organization and pattern formation are key features of life, only very few pattern-forming biochemical systems have been identified that can be reconstituted and studiedin vitrounder defined conditions. A systematic understanding of the underlying mechanisms is often hampered by multiple interactions, conformational flexibility and other complex features of the pattern forming proteins. Because of its compositional simplicity of only two proteins and a membrane, the MinDE system fromEscherichia colihas in the past years been invaluable for deciphering the mechanisms of spatiotemporal self-organizati...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Physics of Living Systems Source Type: research

Antigen presentation and tumor immunogenicity in cancer immunotherapy response prediction
This study suggests that TIGS is an effective tumor-inherent biomarker for ICI-response prediction. (Source: eLife)
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Cancer Biology Genetics and Genomics Source Type: research

Entry by multiple picornaviruses is dependent on a pathway that includes TNK2, WASL and NCK1
Comprehensive knowledge of the host factors required for picornavirus infection would facilitate antiviral development. Here we demonstrate roles for three human genes,TNK2,WASL, andNCK1, in infection by multiple picornaviruses. CRISPR deletion ofTNK2,WASL orNCK1 reduced encephalomyocarditis virus (EMCV), coxsackievirus B3 (CVB3), poliovirus and enterovirus D68 infection, and chemical inhibitors of TNK2 and WASL decreased EMCV infection. Reduced EMCV lethality was observed in mice lacking TNK2. TNK2, WASL and NCK1 were important in early stages of the viral lifecycle, and genetic epistasis analysis demonstrated that the th...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

Nucleolar dynamics and interactions with nucleoplasm in living cells
Liquid-liquid phase separation (LLPS) has been recognized as one of the key cellular organizing principles and was shown to be responsible for formation of membrane-less organelles such as nucleoli. Although nucleoli were found to behave like liquid droplets, many ramifications of LLPS including nucleolar dynamics and interactions with the surrounding liquid remain to be revealed. Here, we study the motion of human nucleoliin vivo, while monitoring the shape of the nucleolus-nucleoplasm interface. We reveal two types of nucleolar pair dynamics: an unexpected correlated motion prior to coalescence and an independent motion ...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Physics of Living Systems Structural Biology and Molecular Biophysics Source Type: research

Demographic reconstruction from ancient DNA supports rapid extinction of the great auk
The great auk was once abundant and distributed across the North Atlantic. It is now extinct, having been heavily exploited for its eggs, meat, and feathers. We investigated the impact of human hunting on its demise by integrating genetic data, GPS-based ocean current data, and analyses of population viability. We sequenced complete mitochondrial genomes of 41 individuals from across the species ’ geographic range and reconstructed population structure and population dynamics throughout the Holocene. Taken together, our data do not provide any evidence that great auks were at risk of extinction prior to the onset of ...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Evolutionary Biology Genetics and Genomics Source Type: research

Evolutionarily conserved long-chain Acyl-CoA synthetases regulate membrane composition and fluidity
The human AdipoR1 and AdipoR2 proteins, as well as theirC. eleganshomolog PAQR-2, protect against cell membrane rigidification by exogenous saturated fatty acids by regulating phospholipid composition. Here, we show that mutations in theC. elegans geneacs-13 help to suppress the phenotypes ofpaqr-2 mutant worms, including their characteristic membrane fluidity defects.acs-13encodes a homolog of the human acyl-CoA synthetase ACSL1, and localizes to the mitochondrial membrane where it likely activates long chains fatty acids for import and degradation. Using siRNA combined with lipidomics and membrane fluidity assays (FRAP a...
Source: eLife - November 26, 2019 Category: Biomedical Science Tags: Cell Biology Source Type: research

Novel charged sodium and calcium channel inhibitor active against neurogenic inflammation
Voltage-dependent sodium and calcium channels in pain-initiating nociceptor neurons are attractive targets for new analgesics. We made a permanently charged cationic derivative of an N-type calcium channel-inhibitor. Unlike cationic derivatives of local anesthetic sodium channel blockers like QX-314, this cationic compound inhibited N-type calcium channels more effectively with extracellular than intracellular application. Surprisingly, the compound is also a highly effective sodium channel inhibitor when applied extracellularly, producing more potent inhibition than lidocaine or bupivacaine. The charged inhibitor produced...
Source: eLife - November 25, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Apolipoprotein M-bound sphingosine-1-phosphate regulates blood –brain barrier paracellular permeability and transcytosis
The blood-brain barrier (BBB) is formed by the endothelial cells lining cerebral microvessels, but how blood-borne signaling molecules influence permeability is incompletely understood. We here examined how the apolipoprotein M (apoM)-bound sphingosine 1 –phosphate (S1P) signaling pathway affects the BBB in different categories of cerebral microvessels using ApoM deficient mice (Apom-/-). We used two-photon microscopy to monitor BBB permeability of sodium fluorescein (376 Da), Alexa Fluor (643 Da), and fluorescent albumin (45 kDA). We show that BBB permeability to small molecules increases inApom-/- mice. Vesicle-med...
Source: eLife - November 25, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Novel genetic loci affecting facial shape variation in humans
The human face represents a combined set of highly heritable phenotypes, but knowledge on its genetic architecture remains limited, despite the relevance for various fields. A series of genome-wide association studies on 78 facial shape phenotypes quantified from 3-dimensional facial images of 10,115 Europeans identified 24 genetic loci reaching study-wide suggestive association (p
Source: eLife - November 25, 2019 Category: Biomedical Science Tags: Genetics and Genomics Source Type: research

Asymmetrical diversification of the receptor-ligand interaction controlling self-incompatibility in Arabidopsis
How two-component genetic systems accumulate evolutionary novelty and diversify in the course of evolution is a fundamental problem in evolutionary systems biology. In the Brassicaceae, self-incompatibility (SI) is a spectacular example of a diversified allelic series in which numerous highly diverged receptor-ligand combinations are segregating in natural populations. However, the evolutionary mechanisms by which new SI specificities arise have remained elusive. Usingin planta ancestral protein reconstruction, we demonstrate that two allelic variants segregating as distinct receptor-ligand combinations diverged through an...
Source: eLife - November 25, 2019 Category: Biomedical Science Tags: Evolutionary Biology Plant Biology Source Type: research

Chromatin-bound CRM1 recruits SET-Nup214 and NPM1c onto < i > HOX < /i > clusters causing aberrant < i > HOX < /i > expression in leukemia cells
We previously demonstrated that CRM1, a major nuclear export factor, accumulates atHox cluster regions to recruit nucleoporin-fusion protein Nup98HoxA9, resulting in robust activation ofHox genes (Oka et al., 2016). However, whether this phenomenon is general to other leukemogenic proteins remains unknown. Here, we show that two other leukemogenic proteins, nucleoporin-fusion SET-Nup214 and the NPM1 mutant, NPM1c, which contains a nuclear export signal (NES) at its C-terminus and is one of the most frequent mutations in acute myeloid leukemia, are recruited to theHOX cluster region via chromatin-bound CRM1, leading toHOX g...
Source: eLife - November 22, 2019 Category: Biomedical Science Tags: Cell Biology Chromosomes and Gene Expression Source Type: research

From plasmodesma geometry to effective symplasmic permeability through biophysical modelling
Regulation of molecular transport via intercellular channels called plasmodesmata (PDs) is important for both coordinating developmental and environmental responses among neighbouring cells, and isolating (groups of) cells to execute distinct programs. Cell-to-cell mobility of fluorescent molecules and PD dimensions (measured from electron micrographs) are both used as methods to predict PD transport capacity (i.e., effective symplasmic permeability), but often yield very different values. Here, we build a theoretical bridge between both experimental approaches by calculating the effective symplasmic permeability from a ge...
Source: eLife - November 22, 2019 Category: Biomedical Science Tags: Cell Biology Plant Biology Source Type: research

Prolonged ovarian storage of mature < i > Drosophila < /i > oocytes dramatically increases meiotic spindle instability
Human oocytes frequently generate aneuploid embryos that subsequently miscarry. In contrast,Drosophila oocytes from outbred laboratory stocks develop fully regardless of maternal age. Since matureDrosophila oocytes are not extensively stored in the ovary under laboratory conditions like they are in the wild, we developed a system to investigate how storage affects oocyte quality. The developmental capacity of stored mature Drosophila oocytes decays in a precise manner over 14 days at 25oC. These oocytes are transcriptionally inactive and persist using ongoing translation of stored mRNAs. Ribosome profiling revealed a progr...
Source: eLife - November 22, 2019 Category: Biomedical Science Tags: Developmental Biology Human Biology and Medicine Source Type: research

Cryo-EM structure of the KvAP channel reveals a non-domain-swapped voltage sensor topology
Conductance in voltage-gated ion channels is regulated by membrane voltage through structural domains known as voltage sensors. A single structural class of voltage sensor domain exists, but two different modes of voltage sensor attachment to the pore occur in nature: domain-swapped and non-domain-swapped. Since the more thoroughly studied Kv1-7, Nav and Cav channels have domain-swapped voltage sensors, much less is known about non-domain-swapped voltage-gated ion channels. In this paper, using cryo-EM, we show that KvAP fromAeropyrum pernix has non-domain-swapped voltage sensors as well as other unusual features. The new ...
Source: eLife - November 22, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

Multistability and regime shifts in microbial communities explained by competition for essential nutrients
Microbial communities routinely have several possible species compositions or community states observed for the same environmental parameters. Changes in these parameters can trigger abrupt and persistent transitions (regime shifts) between such community states. Yet little is known about the main determinants and mechanisms of multistability in microbial communities. Here, we introduce and study a consumer-resource model in which microbes compete for two types of essential nutrients each represented by multiple different metabolites. We adapt game-theoretical methods of the stable matching problem to identify all possible...
Source: eLife - November 22, 2019 Category: Biomedical Science Tags: Ecology Source Type: research

Crystal structure of dopamine receptor D4 bound to the subtype selective ligand, L745870
Multiple subtypes of dopamine receptors within the GPCR superfamily regulate neurological processes through various downstream signaling pathways. A crucial question about the dopamine receptor family is what structural features determine the subtype-selectivity of potential drugs. Here, we report the 3.5-angstrom crystal structure of mouse dopamine receptor D4 (DRD4) complexed with a subtype-selective antagonist, L745870. Our structure reveals a secondary binding pocket extended from the orthosteric ligand-binding pocket to a DRD4-specific crevice located between transmembrane helices 2 and 3. Additional mutagenesis studi...
Source: eLife - November 21, 2019 Category: Biomedical Science Tags: Structural Biology and Molecular Biophysics Source Type: research

A projection specific logic to sampling visual inputs in mouse superior colliculus
Using sensory information to trigger different behaviors relies on circuits that pass through brain regions. The rules by which parallel inputs are routed to downstream targets are poorly understood. The superior colliculus mediates a set of innate behaviors, receiving input from>30 retinal ganglion cell types and projecting to behaviorally important targets including the pulvinar and parabigeminal nucleus. Combining transsynaptic circuit tracing with in vivo and ex vivo electrophysiological recordings, we observed a projection-specific logic where each collicular output pathway sampled a distinct set of retinal inputs....
Source: eLife - November 21, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Persistent < i > Mycobacterium tuberculosis < /i > infection in mice requires PerM for successful cell division
The ability ofMycobacterium tuberculosis (Mtb) to persist in its host is central to the pathogenesis of tuberculosis, yet the underlying mechanisms remain incompletely defined. PerM, an integral membrane protein, is required for persistence of Mtb in mice. Here, we show thatperM deletion caused a cell division defect specifically during the chronic phase of mouse infection, but did not affect Mtb ’s cell replication during acute infection. We further demonstrate that PerM is required for cell division in chronically infected mice and in vitro under host-relevant stresses because it is part of the mycobacterial diviso...
Source: eLife - November 21, 2019 Category: Biomedical Science Tags: Microbiology and Infectious Disease Source Type: research

The ribosomal P-stalk couples amino acid starvation to GCN2 activation in mammalian cells
We report on a mammalian CHO cell-based CRISPR-Cas9 mutagenesis screen for genes that contribute to ISR activation by amino acid starvation. Disruption of genes encoding components of the ribosome P-stalk, uL10 and P1, selectively attenuated GCN2-mediated ISR activation by amino acid starvation or interference with tRNA charging without affecting the endoplasmic reticulum unfolded protein stress-induced ISR, mediated by the related eIF2a kinase PERK. Wildtype ribosomes isolated from CHO cells, but not those with P-stalk lesions, stimulated GCN2-dependent eIF2a phosphorylationin vitro. These observations support a model whe...
Source: eLife - November 21, 2019 Category: Biomedical Science Tags: Cell Biology Genetics and Genomics Source Type: research

Ultrastructural heterogeneity of layer 4 excitatory synaptic boutons in the adult human temporal lobe neocortex
Synapses are fundamental building blocks controlling and modulating the 'behavior' of brain networks. How their structural composition, most notably their quantitative morphology underlie their computational properties remains rather unclear, particularly in humans. Here, excitatory synaptic boutons (SBs) in layer 4 (L4) of the temporal lobe neocortex (TLN) were quantitatively investigated. Biopsies from epilepsy surgery were used for fine-scale and tomographic electron microscopy (EM) to generate 3D-reconstructions of SBs. Particularly, the size of active zones (AZs) and that of the three functionally defined pools of syn...
Source: eLife - November 20, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research

Single cell transcriptome atlas of the < i > Drosophila < /i > larval brain
Cell diversity of the brain and how it is affected by starvation, remains largely unknown. Here we introduce a single cell transcriptome atlas of the entireDrosophilafirst instar larval brain. We first assigned cell-type identity based on known marker genes, distinguishing five major groups: neural progenitors, differentiated neurons, glia, undifferentiated neurons and non-neural cells. All major classes were further subdivided into multiple subtypes, revealing biological features of various cell-types. We further assessed transcriptional changes in response to starvation at the single-cell level. While after starvation th...
Source: eLife - November 20, 2019 Category: Biomedical Science Tags: Neuroscience Source Type: research