Biology subjects

Keller, A.

Publications and source records attributed to Keller, A..

At least 109 records · Page 6Linked to original sources

bioRxiv2021

From musk to body odor: decoding olfaction through genetic variation

The olfactory system combines input from multiple receptor types to represent odor information, but there are few explicit examples relating olfactory receptor (OR) activity patterns to odor perception. To uncover these relationships, we performed genome-wide scans on odor-perception phenotypes for ten odors in 1003 Han Chinese and validated results for six of these odors in an ethnically diverse population (n=364). In both populations, we replicated three previously reported associations ({beta}-ionone/OR5A, androstenone/OR7D4, cis-3-hexen-1-ol/OR2J3 LD-band), suggesting that olfactory phenotype/genotype studies are robust across populations. Two novel associations between an OR and odor perception contribute to our understanding of olfactory coding. First, we found a SNP in OR51B2 that associated with trans-3-methyl-2-hexenoic acid, a key component of human underarm odor. Second, we found two linked SNPs associated with the musk Galaxolide in a novel musk receptor, OR4D6, which is also the first OR shown to drive specific anosmia to a musk compound. We also found that the derived alleles of the SNPs reportedly associated with odor perception tend to reduce odor intensity, supporting the hypothesis that the primate olfactory gene repertoire has degenerated over time. This study provides information about coding for human body odor, and gives us insight into broader mechanisms of olfactory coding, such as how differential OR activation can converge on a similar percept.

genetics↗

bioRxiv2021

A human brain vascular atlas reveals diverse cell mediators of Alzheimer's disease risk

The human brain vasculature is of vast medical importance: its dysfunction causes disability and death, and the specialized structure it forms--the blood-brain barrier--impedes treatment of nearly all brain disorders. Yet, no molecular atlas of the human brain vasculature exists. Here, we develop Vessel Isolation and Nuclei Extraction for Sequencing (VINE-seq) to profile the major human brain vascular and perivascular cell types through 143,793 single-nucleus transcriptomes from 25 hippocampus and cortex samples of 17 control and Alzheimers disease (AD) patients. We identify brain region-enriched pathways and genes divergent between humans and mice, including those involved in disease. We describe the principles of human arteriovenous organization, recapitulating a gradual endothelial and punctuated mural cell continuum; but discover that many zonation and cell-type markers differ between species. We discover two subtypes of human pericytes, marked by solute transport and extracellular matrix (ECM) organization; and define perivascular versus meningeal fibroblast specialization. In AD, we observe a selective vulnerability of ECM-maintaining pericytes and gene expression patterns implicating dysregulated blood flow. With an expanded survey of brain cell types, we find that 30 of the top 45 AD GWAS genes are expressed in the human brain vasculature, confirmed in situ. Vascular GWAS genes map to endothelial protein transport, adaptive immune, and ECM pathways. Many are microglia-specific in mice, suggesting an evolutionary transfer of AD risk to human vascular cells. Our work unravels the molecular basis of the human brain vasculature, informing our understanding of overall brain health, disease, and therapy.

neuroscience↗

bioRxiv2021

Xenogeneic Skin Transplantation Promotes Angiogenesis and Tissue Regeneration Through Vitamin D-Activated Trem2+ Macrophages

Skin allo- and xenotransplantation are the standard treatment for major burns when donor sites for autografts are not available and have been shown to significantly accelerate wound healing. Although the cellular elements of foreign grafts are rejected, the extracellular matrix components integrate into the wound and may underlie their beneficial effects on wound healing. The molecular mechanisms defining the relationship between the immune response to foreign grafts and their impact on wound healing have not been fully elucidated. Here, we investigated changes in collagen architecture after xenogeneic implantation of clinically available human biologic scaffolds. We show that collagen deposition in response to the implantation of human split-thickness skin grafts (hSTSG) containing live cells recapitulates normal skin architecture, whereas human acellular dermal matrix (ADM) grafts led to highly aligned collagen deposition, characteristic of fibrosis and scar. Using single-cell RNA-sequencing, we show that macrophage differentiation in response to hSTSG is driven by vitamin D (VD) signaling toward Trem2+ subpopulations with an enrichment of pro-angiogenic and anti-fibrotic transcriptomic programs. We subsequently induced this regenerative subpopulation in vitro by treating bone marrow-derived cells with vitamin D3 and found that hydrogel delivery of Trem2+ macrophages significantly accelerated wound closure in a human-like murine excisional wound model. Our study identifies the preclinical therapeutic potential of Trem2+ macrophages to mitigate fibrosis and promote wound healing and provides a novel effective strategy to develop advanced cell therapies for complex wounds. One Sentence SummaryVitamin D-activated Trem2+ macrophages promote angiogenesis and mitigate fibrosis, providing a novel effective strategy to develop advanced cell therapies for complex wounds.

immunology↗

bioRxiv2020

Divergent profiles of fentanyl withdrawal and associated pain in mice and rats

Opioid abuse has devastating effects on patients, their families, and society. Withdrawal symptoms are severely unpleasant, prolonged, and frequently hinder recovery or lead to relapse. The sharp increase in abuse and overdoses arising from the illicit use of potent and rapidly-acting synthetic opioids, such as fentanyl, highlights the urgency of understanding the withdrawal mechanisms related to these drugs. Progress is impeded by inconsistent reports on opioid withdrawal in different preclinical models. Here, using rats and mice of both sexes, we quantified withdrawal behaviors during spontaneous and naloxone-precipitated withdrawal, following two weeks of intermittent fentanyl exposure. We found that both mice and rats lost weight during exposure and showed increased signs of distress during spontaneous and naloxone precipitated withdrawal. However, these species differed in their expression of withdrawal associated pain, a key contributor to relapse in humans. Spontaneous or ongoing pain was preferentially expressed in rats in both withdrawal conditions, while no change was observed in mice. In contrast, withdrawal associated thermal hyperalgesia was found only in mice. These data suggest that rats and mice diverge in how they experience withdrawal and which aspects of the human condition they most accurately model. These differences highlight each species strengths as model systems and can inform experimental design in studies of opioid withdrawal.

neuroscience↗

bioRxiv2020

Molecular hallmarks of heterochronic parabiosis at single cell resolution

Slowing or reversing biological ageing would have major implications for mitigating disease risk and maintaining vitality. While an increasing number of interventions show promise for rejuvenation, the effectiveness on disparate cell types across the body and the molecular pathways susceptible to rejuvenation remain largely unexplored. We performed single-cell RNA-sequencing on 13 organs to reveal cell type specific responses to young or aged blood in heterochronic parabiosis. Adipose mesenchymal stromal cells, hematopoietic stem cells, hepatocytes, and endothelial cells from multiple tissues appear especially responsive. On the pathway level, young blood invokes novel gene sets in addition to reversing established ageing patterns, with the global rescue of genes encoding electron transport chain subunits pinpointing a prominent role of mitochondrial function in parabiosis-mediated rejuvenation. Intriguingly, we observed an almost universal loss of gene expression with age that is largely mimicked by parabiosis: aged blood reduces global gene expression, and young blood restores it. Altogether, these data lay the groundwork for a systemic understanding of the interplay between blood-borne factors and cellular integrity.

genomics↗

bioRxiv2020

Parabrachial complex processes dura inputs through a direct trigeminal ganglion-to-parabrachial connection

Migraines cause significant disability and contribute heavily to healthcare costs. Irritation of the meninges outermost layer (the dura mater), and trigeminal ganglion activation contribute to migraine initiation. Maladaptive changes in central pain-processing regions are also important in maintaining pain. The parabrachial complex (PB) is a central region that mediates chronic pain. PB receives diverse sensory information, including a direct input from the trigeminal ganglion. We hypothesized that PB processes inputs from the dura. Using in vivo electrophysiology recordings from single units in anesthetized rats we identified 58 neurons in lateral PB that respond reliably and with short latency to electrical dura stimulation. After injecting tracer into PB, anatomical examination reveals retrogradely labeled cell bodies in the trigeminal ganglion. Neuroanatomical tract-tracing revealed a population of neurons in the trigeminal ganglion that innervate the dura and project directly to PB. These findings indicate that PB is strategically placed to process dura inputs, and suggest that it is directly involved in the pathogenesis of migraine headaches.

neuroscience↗

bioRxiv2020

Broad transcriptional dysregulation of brain and choroid plexus cell types with COVID-19

Though SARS-CoV-2 primarily targets the respiratory system, it is increasingly appreciated that patients may suffer neurological symptoms of varied severity1-3. However, an unbiased understanding of the molecular processes across brain cell types that could contribute to these symptoms in COVID-19 patients is still missing. Here, we profile 47,678 droplet-based single-nucleus transcriptomes from the frontal cortex and choroid plexus across 10 non-viral, 4 COVID-19, and 1 influenza patient. We complement transcriptomic data with immunohistochemical staining for the presence of SARS-CoV-2. We find that all major cortex parenchymal and choroid plexus cell types are affected transcriptionally with COVID-19. This arises, in part, from SARS-CoV-2 infection of the cortical brain vasculature, meninges, and choroid plexus, stimulating increased inflammatory signaling into the brain. In parallel, peripheral immune cells infiltrate the brain, microglia activate programs mediating the phagocytosis of live neurons, and astrocytes dysregulate genes involved in neurotransmitter homeostasis. Among neurons, layer 2/3 excitatory neurons--evolutionarily expanded in humans4--show a specific downregulation of genes encoding major SNARE and synaptic vesicle components, predicting compromised synaptic transmission. These perturbations are not observed in terminal influenza. Many COVID-19 gene expression changes are shared with those in chronic brain disorders and reside in genetic variants associated with cognitive function, schizophrenia, and depression. Our findings and public dataset provide a molecular framework and new opportunities to understand COVID-19 related neurological disease.

neuroscience↗

bioRxiv2020

Environmental DNA Metabarcoding for Simultaneous Monitoring and Ecological Assessment of Many Harmful Algae

Harmful algae can have profound economic, environmental, and social consequences. As the timing, frequency, and severity of harmful algal blooms (HABs) change alongside global climate, efficient tools to monitor and understand the current ecological context of these taxa are increasingly important. Here we employ environmental DNA metabarcoding to identify patterns in a wide variety of harmful algae and associated ecological communities in the Hood Canal of Puget Sound in Washington State, USA. We track trends of presence and abundance in a series of water samples across nearly two years. We find putative harmful algal sequences in a majority of samples, suggesting that these groups are routinely present in local waters. We report patterns in variants of the economically important genus Pseudo-nitzschia (family Bacillariaceae), as well as multiple harmful algal taxa previously unknown or poorly documented in the region, including a cold-water variant from the saxitoxin-producing genus Alexandrium (family Gonyaulacaceae), two variants from the karlotoxin-producing genus Karlodinium (family Kareniaceae), and one variant from the parasitic genus Hematodinium (family Syndiniaceae). We then use data on environmental variables and the biological community surrounding each algal taxon to illustrate the ecological context in which these species are commonly found. Environmental DNA metabarcoding thus simultaneously (1) alerts us to potential new or cryptic occurrences of harmful algae, (2) expands our knowledge of the co-occurring conditions and species associated with the growth of these organisms in changing marine environments, and (3) provides a tool for monitoring and management moving forward.

ecology↗

bioRxiv2020

Control of synaptic transmission and neuronal excitability in the parabrachial nucleus

The parabrachial nucleus (PB) is a hub for aversive behaviors, including those related to pain. We have shown that the expression of chronic pain is causally related to amplified activity of PB neurons, and to changes in synaptic inhibition of these neurons. These findings indicate that regulation of synaptic activity in PB may modulate pain perception and be involved in the pathophysiology of chronic pain. Here, we identify the roles in PB of signaling pathways that modulate synaptic functions. In pharmacologically isolated lateral PB neurons in acute mouse slices, we find that baclofen, a GABAB receptor agonist, suppresses the frequency of miniature inhibitory and excitatory postsynaptic currents (mIPSCs and mEPSC). Activation of {micro}-opioid peptide receptors with DAMGO had similar effects, while the k-opioid peptide receptor agonist U-69593 suppressed mIPSC release but had no consistent effects on mEPSCs. Activation of cannabinoid type 1 receptors with WIN 55,212-2 reduced the frequency of both inhibitory and excitatory synaptic events, while the CB1 antagonist AM251 had opposite effects on mIPSC and mEPSC frequencies. AM251 increased the frequency of inhibitory events but led to a reduction in excitatory events through a GABAB mediated mechanism. Although none of the treatments produced a consistent effect on mIPSC or mEPSC amplitudes, baclofen and DAMGO both reliably activated a postsynaptic conductance. Together, these results demonstrate that signaling pathways known to modulate nociception, alter synaptic transmission and neuronal excitability in the lateral parabrachial nucleus and provide a basis for investigating the contributions of these systems to the development and maintenance of chronic pain. HighlightsO_LIThe parabrachial nucleus (PB) is a hub for processing interoceptive and exteroceptive noxious stimuli, including pain. C_LIO_LISynaptic activity in PB is abnormal in chronic pain. C_LIO_LISynaptic activity in PB is regulated by presynaptic and postsynaptic GABAB, opioid {micro} and k, and cannabinoid CB1 receptors. C_LIO_LIGABAergic presynaptic terminals are most potently regulated by these receptors. C_LIO_LIChanges in the strength of these modulatory pathways may contribute to increased PB excitability and, consequently, chronic pain. C_LI

neuroscience↗

bioRxiv2020

Perinatal fentanyl exposure leads to long-lasting impairments in somatosensory circuit function and behavior

One consequence of the opioid epidemic are lasting neurodevelopmental sequelae afflicting adolescents exposed to opioids in the womb. A translationally relevant and developmentally accurate preclinical model is needed to understand the behavioral, circuit, network, and molecular abnormalities resulting from this exposure. By employing a novel preclinical model of perinatal fentanyl exposure, our data reveal that fentanyl has several dose-dependent, developmental consequences to somatosensory function and behavior. Newborn male and female mice exhibit signs of withdrawal and sensory-related deficits that extend at least to adolescence. As fentanyl exposure does not affect dams health or maternal behavior, these effects result from the direct actions of perinatal fentanyl on the pups developing brain. At adolescence, exposed mice exhibit reduced adaptation to sensory stimuli, and a corresponding impairment in primary somatosensory (S1) function. In vitro electrophysiology demonstrates a long-lasting reduction in S1 synaptic excitation, evidenced by decreases in release probability, NMDA receptor-mediated postsynaptic currents, and frequency of miniature excitatory postsynaptic currents, as well as increased frequency of miniature inhibitory postsynaptic currents. In contrast, anterior cingulate cortical neurons exhibit an opposite phenotype, with increased synaptic excitation. Consistent with these canghes, electrocorticograms reveal suppressed ketamine-evoked {gamma} oscillations. Morphological analysis of S1 pyramidal neurons indicate reduced dendritic complexity, dendritic length, and soma size. Further, exposed mice exhibited abnormal cortical mRNA expression of key receptors and neuronal growth and development, changes that were consistent with the electrophysiological and morphological changes. These findings demonstrate the lasting sequelae of perinatal fentanyl exposure on sensory processing and function.

neuroscience↗

bioRxiv2020

Distinct signatures of calcium activity in brain pericytes

Even though pericytes have been implicated in various neurological disorders, little is known about their function and signaling pathways in the healthy brain. Here, we characterized cortical pericyte calcium dynamics using two-photon imaging of Pdgfr{beta}-CreERT2;GCaMP6s mice under anesthesia in vivo and in brain slices ex vivo. We found distinct differences between pericyte subtypes in vivo: Ensheathing pericytes exhibited smooth muscle cell-like calcium dynamics, while calcium signals in capillary pericytes were irregular, higher in frequency and occurred in cellular microdomains. In contrast to ensheathing pericytes, capillary pericytes retained their spontaneous calcium signals during prolonged anesthesia and in the absence of blood flow ex vivo. Chemogenetic activation of neurons in vivo and acute increase of extracellular potassium in brain slices strongly decreased calcium activity in capillary pericytes. We propose that neuronal activity-induced elevations in extracellular potassium suppress calcium activity in capillary pericytes, likely mediated by Kir2.2 and KATP channel activation.

neuroscience↗

bioRxiv2020

Endogenous suppression of WNT signalling in human embryonic stem cells leads to low differentiation propensity towards definitive endoderm

SummaryLow differentiation propensity towards a targeted lineage can significantly hamper the utility of individual human pluripotent stem cell (hPSC) lines in biomedical applications. Here, we use monolayer and micropatterned cell cultures, as well as transcriptomic profiling, to investigate how variability in signalling pathway activity between human embryonic stem cell lines affects their differentiation efficiency towards definitive endoderm (DE). We show that endogenous suppression of WNT signalling in hPSCs at the onset of differentiation prevents the switch from self-renewal to DE specification. Gene expression profiling reveals that this inefficient switch is reflected in NANOG expression dynamics. Importantly, we demonstrate that higher WNT stimulation or inhibition of the PI3K/AKT signalling can overcome the DE commitment blockage. Our findings highlight that redirection of the activity of Activin/NODAL pathway by WNT signalling towards mediating DE fate specification is a vulnerable spot, as disruption of this process can result in poor hPSC specification towards DE.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2020

Constitutional activation of BMP4 and WNT signalling in hESC results in impaired mesendoderm differentiation

We identified a human embryonic stem cell subline that fails to respond to the differentiation cues needed to obtain mesendoderm derivatives, differentiating into trophoblast-like cells instead. RNA-sequencing analysis showed that the subline has hyperactivation of the WNT and BMP4 signalling. Modulation of these pathways with small molecules confirmed them as the cause of the differentiation impairment. While activation of WNT and BMP4 in control cells resulted in a loss of mesendoderm differentiation and induction of trophoblast markers, inhibition of these pathways in the subline restored its ability to differentiate. Karyotyping and exome sequencing analysis did not identify any changes in the genome that could account for the pathway deregulation. These findings add to the increasing evidence that different responses of stem cell lines to differentiation protocols are based on genetic and epigenetic factors, inherent to the line or acquired during cell culture.

cell biology↗

bioRxiv2020

Deep sncRNA-seq of the PPMI cohort to study Parkinson's disease progression

Coding and non-coding RNAs have diagnostic and prognostic importance in Parkinsons diseases (PD). We studied circulating small non-coding RNAs (sncRNAs) in 7, 003 samples from two longitudinal PD cohorts (Parkinsons Progression Marker Initiative (PPMI) and Luxembourg Parkinsons Study (NCER-PD)) and modelled their influence on the transcriptome. First, we sequenced sncRNAs in 5, 450 blood samples of 1, 614 individuals in PPMI. The majority of 323 billion reads (59 million reads per sample) mapped to miRNAs. Other covered RNA classes include piRNAs, rRNAs, snoRNAs, tRNAs, scaRNAs, and snRNAs. De-regulated miRNAs were associated with the disease and disease progression and occur in two distinct waves in the third and seventh decade of live. Originating mostly from a characteristic set of immune cells they resemble a systemic inflammation response and mitochondrial dysfunction, two hallmarks of PD. By profiling 1, 553 samples from 1, 024 individuals in the NCER-PD cohort using an independent technology, we validate relevant findings from the sequencing study. Finally, network analysis of sncRNAs and transcriptome sequencing of the original cohort identified regulatory modules emerging in progressing PD patients.

neuroscience↗

bioRxiv2020

Unraveling the interaction between doxorubicin and DNA origami nanostructures for customizable chemotherapeutic drug release

Doxorubicin (DOX) is a common drug in cancer chemotherapy, and its high DNA-binding affinity can be harnessed in preparing DOX-loaded DNA nanostructures for targeted delivery and therapeutics. Although DOX has been widely studied, the existing literature of DOX-loaded DNA-carriers remains limited and incoherent. Here, based on an in-depth spectroscopic analysis, we characterize and optimize the DOX loading into different 2D and 3D scaffolded DNA origami nanostructures (DONs). In our experimental conditions, all DONs show similar DOX binding capacities (one DOX molecule per two to three base pairs), and the binding equilibrium is reached within seconds, remarkably faster than previously acknowledged. To characterize drug release profiles, DON degradation and DOX release from the complexes upon DNase I digestion was studied. For the employed DONs, the relative doses (DOX molecules released per unit time) may vary by two orders of magnitude depending on the DON superstructure. In addition, we identify DOX aggregation mechanisms and spectral changes linked to pH, magnesium, and DOX concentration. These features have been largely ignored in experimenting with DNA nanostructures, but are probably the major sources of the incoherence of the experimental results so far. Therefore, we believe this work can act as a guide to tailoring the release profiles and developing better drug delivery systems based on DNA-carriers.

biochemistry↗

bioRxiv2020

Changes amid constancy: flower and leaf microbiomes along land use gradients and between bioregions

Microbial communities inhabiting above-ground parts of plants affect their hosts development, fitness and function. Although studies on plant-associated microbes are of growing interest, environmental drivers of flower microbiomes in particular are poorly characterized. In this study, we investigated flower and leaf epiphytic bacterial microbiomes of Ranunculus acris and Trifolium pratense using metabarcoding of 16S ribosomal DNA in three German bioregions and along land-use intensity gradients. Our data suggests that the structures of bacterial communities clearly differed between plant species and tissue types. Also, floral bacterial communities of R. acris showed higher variability in comparison to T. pratense. Bacteria usually associated with pollinators were found solely in flower samples, while such usually associated with the rhizosphere were only present in high abundances on leaves. We identified Pseudomonadaceae, Enterobacteriaceae and Sphingomonadaceae as the most abundant taxa on flowers, while Sphingomonadaceae, Methylobacteriaceae and Cytophagaceae dominated bacterial communities on leaves. We found strong bacterial turnover already for short geographic distances, which however did not increase with the long distances between bioregions. High land use intensity caused phylogenetically less diverse and more homogenous bacterial communities. This was associated with a loss of rare bacterial families. Intensification of mowing and fertilization affected almost all plant associated bacterial communities, while grazing had only minor effects on bacterial structures of T. pratense flowers. However, dominant taxa were mostly resilient to mowing, grazing and fertilization. Despite that, we identified indicator taxa for regularly disturbed environments in flower microbiomes.

ecology↗

bioRxiv2020

Competitive learning suggests circulating miRNA profiles for cancers decades prior to diagnosis

Small non-coding RNAs such as microRNAs are master regulators of gene expression. One of the most promising applications of miRNAs is the use as liquid biopsy. Especially early diagnosis is an effective means to increase patients overall survival. E.g. in oncology a tumor is detected at best prior to its clinical manifestation. We generated genome-wide miRNA profiles from serum of patients and controls from the population-based Janus Serum Bank (JSB) and analyzed them by bioinformatics and artificial intelligence approaches. JSB contains sera from 318,628 originally healthy persons, more than 96,000 of whom later developed cancer. We selected 210 serum samples of patients with lung, colon or breast cancer at three time points prior to diagnosis, after cancer diagnosis and controls. The controls were matched with regard to age of the blood donor and to the time points of blood drawing, which were 27, 32, or 38 years prior to diagnosis. Using ANOVA we report 70 significantly deregulated markers (adjusted p-value<0.05). The driver for the significance was the diagnostic time point (miR-575, miR-6821-5p, miR-630 had adjusted p-values<10-10). Further, 91miRNAs were differently expressed in pre-diagnostic samples as compared to controls (nominal p<0.05). Unsupervised competitive learning by self-organized maps indicated larges effects in lung cancer samples while breast cancer samples showed the least pronounced changes. Self-organized maps also highlighted cancer and time point specific miRNA dys-regulation. Intriguingly, a detailed breakdown of the results highlighted that 51% of all miRNAs were highly specific, either for a time-point or a cancer entity. Our results indicate that tumors may be indicated by serum miRNAs decades prior the clinical manifestation.

cancer biology↗

bioRxiv2020

CRISPR/Cas9 mediated mutations as a new tool for studying taste in honeybees

BackgroundHoneybees rely on nectar as their main source of carbohydrates [1]. Sucrose, glucose and fructose are the main components of plant nectars [2] [3]. Intriguingly, honeybees express only three putative sugar receptors (AmGr1, AmGr2 and AmGr3) [4], which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized [5] [6]. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. ResultsWe show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioural change and serve to characterize the function of taste receptors in vivo. ConclusionCRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterisation in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=166 HEIGHT=200 SRC="FIGDIR/small/009696v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1100f07org.highwire.dtl.DTLVardef@14ac138org.highwire.dtl.DTLVardef@d37468org.highwire.dtl.DTLVardef@7f6abb_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 0C_FLOATNO C_FIG

genetics↗