Biology subjects

Xu, P.

Publications and source records attributed to Xu, P..

At least 235 records · Page 13Linked to original sources

bioRxiv2020

Transient "rest" induces functional reinvigoration and epigenetic remodeling in exhausted CAR-T cells

T cell exhaustion limits immune responses against cancer and is a major cause of resistance to CAR-T cell therapeutics. Using a model wherein tonic CAR signaling induces hallmark features of exhaustion, we employed a drug-regulatable CAR to test the impact of transient cessation of receptor signaling (i.e. "rest") on the development and maintenance of exhaustion. Induction of rest in exhausting or already-exhausted CAR-T cells resulted in acquisition of a memory-like phenotype, improved anti-tumor functionality, and wholescale transcriptional and epigenetic reprogramming. Similar results were achieved with the Src kinase inhibitor dasatinib, which reversibly suppresses CAR signaling. The degree of functional reinvigoration was proportional to the duration of rest and was associated with expression of transcription factors TCF1 and LEF1. This work demonstrates that transient cessation of CAR-T cell signaling can enhance anti-tumor potency by preventing or reversing exhaustion and challenges the paradigm that exhaustion is an epigenetically fixed state.

immunology↗

bioRxiv2019

Compensatory guaiacyl lignin biosynthesis at the expense of syringyl lignin in 4CL1-knockout poplar

The lignin biosynthetic pathway is highly conserved in angiosperms, yet pathway manipulations give rise to a variety of taxon-specific outcomes. Knockout of lignin-associated 4-coumarate:CoA ligases (4CLs) in herbaceous species mainly reduces guaiacyl (G) lignin and enhances cell wall saccharification. Here we show that CRISPR-knockout of 4CL1 in Populus tremula x alba preferentially reduced syringyl (S) lignin, with negligible effects on biomass recalcitrance. Concordant with reduced S-lignin was downregulation of ferulate 5-hydroxylases (F5Hs). Lignification was largely sustained by 4CL5, a low-affinity paralog of 4CL1 typically with only minor xylem expression or activity. Levels of caffeate, the preferred substrate of 4CL5, increased in line with significant upregulation of caffeoyl shikimate esterase1. Upregulation of caffeoyl-CoA O-methyltransferase1 and downregulation of F5Hs are consistent with preferential funneling of 4CL5 products toward G-lignin biosynthesis at the expense of S-lignin. Thus, transcriptional and metabolic adaptations to 4CL1-knockout appear to have enabled 4CL5 catalysis at a level sufficient to sustain lignification. Finally, genes involved in sulfur assimilation, the glutathione-ascorbate cycle and various antioxidant systems were upregulated in the mutants, suggesting cascading responses to perturbed thioesterification in lignin biosynthesis. One sentence summaryKnockout of lignin-associated 4CL1 in Populus reveals a 4CL5-dependent, caffeate-modulated compensatory pathway for lignification with links to thiol redox balance and sulfur assimilation.

plant biology↗

bioRxiv2019

CRISPR-Cas12a/Cpf1-assisted precise, efficient and multiplexed genome-editing in Yarrowia lipolytica

CRISPR-Cas9 has been widely adopted as the basic toolkit for precise genome-editing and engineering in various organisms. Alternative to Cas9, Cas12 or Cpf1 uses a simple crRNA as a guide and expands the protospacer adjacent motif (PAM) sequence to TTTN. This unique PAM sequence of Cpf1 may significantly increase the on-target editing efficiency due to lower chance of Cpf1 misreading the PAMs on a high GC genome. To demonstrate the utility of CRISPR-Cpf1, we have optimized the CRISPR-Cpf1 system and achieved high-editing efficiency for two counter-selectable markers in the industrially-relevant oleaginous yeast Yarrowia lipolytica: arginine permease (93% for CAN1) and orotidine 5-phosphate decarboxylase ([~]96% for URA3). Both mutations were validated by indel mutation sequencing. For the first time, we further expanded this toolkit to edit three sulfur house-keeping genetic markers (40%-75% for MET2, MET6 and MET25), which confers yeast distinct colony color changes due to the formation of PbS (lead sulfide) precipitates. Different from Cas9, we demonstrated that the crRNA transcribed from a standard type II RNA promoter was sufficient to guide Cpf1 endonuclease activity. Furthermore, modification of the crRNA with 3 polyUs facilitates the faster maturation and folding of crRNA and improve the genome editing efficiency. We also achieved multiplexed genome editing, and the editing efficiency reached 75%-83% for duplex genomic targets (CAN1-URA3 and CAN1-MET25) and 41.7% for triplex genomic targets (CAN1-URA3-MET25). Taken together, this work expands the genome-editing toolbox for oleaginous yeast species and may accelerate our ability to engineer oleaginous yeast for both biotechnological and biomedical applications.

synthetic biology↗

bioRxiv2019

Analytical solution for a hybrid Logistic-Monod cell growth model in batch and CSTR culture

Monod and Logistic growth models have been widely used as basic equations to describe cell growth in bioprocess engineering. In the case for Monod equation, specific growth rate is governed by a limiting nutrient, with the mathematical form similar to the Michaelis-Menten equation. In the case for Logistic equation, specific growth rate is determined by the carrying capacity of the system, which could be growth-inhibiting factors (i.e. toxic chemical accumulation) other than the nutrient level. Both equations have been found valuable to guide us build structure-based kinetic models to analyze fermentation process and understand cell physiology. In this work, we present a hybrid Logistic-Monod growth model, which accounts for multiple growth-dependence factors including both the limiting nutrient and the carrying capacity of the system. Coupled with substrate consumption and yield coefficient, we present the analytical solutions for this hybrid Logistic-Monod model in both batch and CSTR culture. Under high biomass yield (Yx/s) conditions, the analytical solution for this hybrid model is approaching to the Logistic equation; under low biomass yield condition, the analytical solution for this hybrid model converges to the Monod equation. This hybrid Logistic-Monod equation represents the cell growth transition from substrate-limiting condition to growth-inhibiting condition, which could be adopted to accurately describe the multi-phases of cell growth and may facilitate kinetic model construction, bioprocess optimization and scale-up in industrial biotechnology.

bioengineering↗

bioRxiv2019

Branch point control at malonyl-CoA node: A computational framework to optimize the controller architecture toward ideal metabolic switches

Living organism is an intelligent system encoded by hierarchically-organized information to perform precisely-controlled biological functions. Biophysical models are important tools to uncover the design rules underlying complex genetic-metabolic circuit interactions. Based on a previously engineered synthetic malonyl-CoA switch (Xu et al, PNAS 2014), we have formulated nine differential equations to unravel the design principles underlying an ideal metabolic switch to improve fatty acids production in E. coli. By interrogating the physiologically accessible parameter space, we have determined the optimal controller architecture to configure both the metabolic source pathway and metabolic sink pathway. We determined that low protein degradation rate, medium strength of metabolic inhibitory constant, high metabolic source pathway induction rate, strong binding affinity of the transcriptional activator toward the metabolic source pathway, weak binding affinity of the transcriptional repressor toward the metabolic sink pathway, and a strong cooperative interaction of transcriptional repressor toward metabolic sink pathway benefit the accumulation of the target molecule (fatty acids). The target molecule (fatty acid) production is increased from 50% to 10-folds upon application of the autonomous metabolic switch. With strong metabolic inhibitory constant, the system displays multiple steady states. Stable oscillation of metabolic intermediate is the driving force to allow the system deviate from its equilibrium state and permits bidirectional ON-OFF gene expression control, which autonomously compensates enzyme level for both the metabolic source and metabolic sink pathways. The computational framework may facilitate us to design and engineer predictable genetic-metabolic switches, quest for the optimal controller architecture of the metabolic source/sink pathways, as well as leverage autonomous oscillation as a powerful tool to engineer cell function.

synthetic biology↗

bioRxiv2019

High-depth resequencing reveals hybrid population and insecticide resistance characteristics of fall armyworm (Spodoptera frugiperda) invading China

The rapid wide-scale spread of fall armyworm (Spodoptera frugiperda) has caused serious crop losses globally. However, differences in the genetic background of subpopulations and the mechanisms of rapid adaptation behind the invasion are still not well understood. Here we report a 393.25-M chromosome-level genome assembly of fall armyworm with scaffold N50 of 13.3 M consisting of 23281 annotated protein-coding genes. Genome-wide resequencing of 105 samples from 16 provinces in China revealed that the fall armyworm population comprises a complex inter-strain hybrid, mainly with the corn-strain genetic background and less of the rice-strain genetic background, which highlights the inaccuracy of strain identification using mitochondrial or Tpi genes. An analysis of genes related to pesticide- and Bt-resistance showed that the risk of fall armyworm developing resistance to conventional pesticides is very high, while remaining currently susceptible to Bt toxins. Laboratory bioassay results showed that insects invading China carry resistance to organophosphate and pyrethroid pesticides, but are sensitive to genetically modified maize expressing Cry1Ab in field experiments. Additionally, we found that two mitochondrial fragments are inserted into the nuclear genome, and the insertion event occurred after the differentiation of the two strains. This study represents a valuable advancement toward the analysis of genetic differences among subpopulations and improving management strategies for fall armyworm.

genomics↗

bioRxiv2019

MeCP2 deletion impaired layer 2/3-dominant dynamic reorganization of cortical circuit during motor skill learning

Rett Syndrome (RTT) is a severe neurodevelopmental disorder caused by loss of function of the X-linked Methyl-CpG-binding protein 2 (MECP2). Several case studies report that gross motor function can be improved in children with RTT through treadmill walking, but whether the MeCP2-deficient motor circuit can support actual motor learning remains unclear. We used two-photon calcium imaging to simultaneously observe layer (L) 2/3 and L5a excitatory neuronal activity in the motor cortex (M1) while mice adapted to changing speeds on a computerized running wheel. Despite circuit hypoactivity and weakened functional connectivity across L2/3 and L5a, the Mecp2-null circuits firing pattern evolved with improved performance over two weeks. Moreover, trained mice became less anxious and lived 20% longer than untrained mice. Since motor deficits and anxiety are core symptoms of Rett, which is not diagnosed until well after symptom onset, these results underscore the benefit of motor learning.

neuroscience↗

bioRxiv2019

CO2 per se activates carbon dioxide receptors

Carbon dioxide has been used in traps for more than six decades to monitor mosquito populations and help make informed vector management decisions. CO2 is sensed by gustatory receptors (GRs) housed in neurons in the maxillary palps. CO2-sensitive GRs have been identified from the vinegar fly and mosquitoes, but it remains to be resolved whether these receptors respond to CO2 or bicarbonate. As opposed to the vinegar fly, mosquitoes have three GR subunits, but it is assumed that subunits GR1 and GR3 form functional receptors. In our attempt to identify the chemical species that bind these receptors, we discovered that GR2 and GR3 are essential for receptor function and that GR1 appears to function as a modulator. While Xenopus oocytes coexpressing Culex quinquefasciatus subunits CquiGR1/3 and CquiGR1/2 were not activated, CquiGR2/3 gave robust responses to sodium bicarbonate. Interestingly, CquiGR1/2/3- coexpressing oocytes gave significantly lower responses. That the tertiary combination is markedly less sensitive than the GR2/GR3 combination was also observed with orthologs from the yellow fever and the malaria mosquito. By comparing responses of CquiGR2/CquiGR3- coexpressing oocytes to sodium bicarbonate samples (with or without acidification) and measuring the concentration of aqueous CO2, we showed that there is a direct correlation between dissolved CO2 and receptor response. We then concluded that subunits GR2 and GR3 are essential for these carbon dioxide-sensitive receptors and that they are activated by CO2 per se, not bicarbonate.

neuroscience↗

bioRxiv2019

Direct anabolic three carbon metabolism to a six carbon metabolite occurs in human heart and in vivo across mouse tissues

Anabolic metabolism of carbon in mammals is mediated via the one and two carbon carriers S-adenosyl methionine and acetyl-coenzyme A (acetyl-CoA). In contrast, anabolic metabolism using three carbon units via propionate is not thought to occur. Mammals are primarily thought to oxidize the 3-carbon short chain fatty acid propionate by shunting propionyl-CoA to succinyl-CoA for entry into the TCA cycle. We found that this may not be absolute and that in mammals one non-oxidative fate of two units of propionyl-CoA is to condense to a six-carbon trans-2-methyl-2-pentenoyl-CoA (2M2PE-CoA). We confirmed this pathway using purified protein extracts provided limited substrates and confirmed the product with a synthetic standard. In whole-body in vivo stable isotope tracing with infusion of 13C-labeled valine achieving steady state, 2M2PE-CoA formed via propionyl-CoA in multiple murine tissues including heart, kidney, and to a lesser degree in brown adipose tissue, liver, and tibialis anterior muscle. Using ex vivo isotope tracing, we found that 2M2PE-CoA formed in human myocardial tissue incubated with propionate to a limited extent. While the complete enzymology of this pathway remains to be elucidated, these results confirm the in vivo existence of at least one anabolic three to six carbon reaction conserved in humans and mice that utilizes three carbons via propionate. Highlights- Synthesis and confirmation of structure 2-methyl-2-pentenoyl-CoA - In vivo fate of valine across organs includes formation of a 6-carbon metabolite from propionyl-CoA - Ex vivo metabolism of propionate in the human heart includes direct anabolism to a 6-carbon product - In both cases, this reaction occurred at physiologically relevant concentrations of propionate and valine - In vitro this pathway requires propionyl-CoA and NADH/NADPH as substrates

biochemistry↗

bioRxiv2019

Transcriptomic Profiling of Developing Melanocortin Neurons Reveals a Role for Prdm12 in Energy Balance

The hypothalamus is a critical regulator of many physiological processes essential for life. In the adult brain, each anatomically-defined hypothalamic nucleus consists of functionally heterogeneous neuronal subpopulations that dictate distinct survival behaviors. Nevertheless, how rich neuronal identities are established in the developing hypothalamus remains poorly understood.\n\nDespite their opposing actions on food intake, POMC and NPY/AgRP neurons in the arcuate nucleus of the hypothalamus (ARH) are derived from the same progenitors that give rise to ARH neurons. However, the mechanism whereby common neuronal precursors subsequently adopt either the anorexigenic (POMC) or the orexigenic (NPY/AgRP) identity remains elusive.\n\nWe hypothesize that POMC and NPY/AgRP cell fates are specified and maintained by distinct intrinsic factors. In search of them, we profiled the transcriptomes of developing POMC and NPY/AgRP neurons with whole-genome RNA sequencing (RNA-seq). Moreover, cell-type-specific transcriptomic analyses revealed transcription regulators that are selectively enriched in either population, but whose developmental functions are unknown in these neurons.\n\nAmong them, we found the expression of the PR domain-containing factor 12 (Prdm12) was enriched in POMC neurons but was absent in NPY/AgRP neurons. Selective ablation of Prdm12 in postmitotic POMC neurons led to early-onset obesity, accelerated linear growth, as well as impaired glucose tolerance, which recapitulates symptoms of POMC/MC4R deficiency in humans. These findings, therefore, establish a previously-unrecognized role for Prdm12 in energy balance. Furthermore, the combination of cell-type-specific genomic and genetic analyses provides a means to dissect cellular and functional diversity in the developing hypothalamus as well as the developmental origins of diverse survival behaviors.

neuroscience↗

bioRxiv2019

Subcellular metabolic pathway kinetics are revealed by correcting for artifactual post harvest metabolism

OBJECTIVEThe dynamic regulation of metabolic pathways can be monitored by stable isotope tracing. Yet, many metabolites are part of distinct processes within different subcellular compartments. Standard isotope tracing experiments relying on analyses in whole cells may not accurately reflect compartmentalized metabolic processes. Analysis of compartmentalized metabolism and the dynamic interplay between compartments can potentially be achieved by stable isotope tracing followed by subcellular fractionation. Although it is recognized that metabolism can take place during biochemical fractionation of cells, a clear understanding of how such post-harvest metabolism impacts the interpretation of subcellular isotope tracing data and methods to correct for this are lacking. We set out to directly assess artifactual metabolism, enabling us to develop and test strategies to correct for it. We apply these techniques to examine the compartment-specific metabolic kinetics of 13C-labeled substrates targeting central metabolic pathways.\n\nMETHODSWe designed a stable isotope tracing strategy to interrogate post-harvest metabolic activity during subcellular fractionation using liquid chromatography-mass spectrometry (LC-MS).\n\nRESULTSWe show that post-harvest metabolic activity occurs rapidly (within seconds) upon cell harvest. With further characterization we reveal that this post-harvest metabolism is enzymatic, and reflects the metabolic capacity of the sub-cellular compartment analyzed; but is limited in the extent of its propagation into downstream metabolites in metabolic pathways. We also propose and test a post-labeling strategy to assess the amount of post-harvest metabolism occurring in an experiment and then to adjust data to account for this. We validate this approach for both mitochondrial and cytosolic metabolic analyses.\n\nCONCLUSIONSOur data indicate that isotope tracing coupled with sub-cellular fractionation can reveal distinct and dynamic metabolic features of cellular compartments, and that confidence in such data can be improved by applying a post-labeling correction strategy. We examine compartmentalized metabolism of acetate and glutamine and show that acetyl-CoA is turned over rapidly in the cytosol and acts as a pacemaker of anabolic metabolism in this compartment.

biochemistry↗

bioRxiv2019

A cold shock protein from a thermophile bacterium promotes the high-temperature growth of bacteria and fungi through binding to diverse RNA species

High temperatures deleteriously affect cells by damaging cellular structures and changing the behavior of diverse biomolecules, and extensive research about thermophilic microorganisms has elucidated some of the mechanisms that can overcome these effects and allow thriving in high-temperature ecological niches. We here used functional genomics methods to screen out a cold-shock protein (CspL) from a high-productivity lactate producing thermophile strain (Bacillus coagulans strain 2-6) grown at 37{degrees}C and 60{degrees}C. We subsequently made the highly striking finding that transgenic expression of CspL conferred massive increases in high temperature growth of other organisms including E. coli (2.4-fold biomass increase at 45{degrees}C) and the eukaryote S. cerevisiae (a 2.7-fold biomass increase at 34{degrees}C). Pursuing these findings, we used bio-layer interferometry assays to characterize the nucleotide-binding function of CspL in vitro, and used proteomics and RNA-Seq to characterize the global effects of CspL on mRNA transcript accumulation and used RIP-Seq to identify in vivo RNA targets of this nucleotide-binding protein (e.g. rpoE, and rmf, etc.). Finally, we confirmed that a nucleotide-binding-dead variant form of CspL does not have increased growth rates or biomass accumulation effects at high temperatures. Our study thus establishes that CspL can function as a global RNA chaperone.

microbiology↗

bioRxiv2019

Glycoproteomic measurement of site-specific polysialylation

Polysialylation is the enzymatic addition of a highly negatively charged sialic acid polymer to the non-reducing termini of glycans. Polysialylation plays an important role in development, and is involved in neurological diseases, neural tissue regeneration, and cancer. Polysialic acid (PSA) is also a biodegradable and non-immunogenic conjugate to therapeutic drugs to improve their pharmacokinetics. PSA chains vary in length, composition, and linkages, while the specific sites of polysialylation are important determinants of protein function. However, PSA is difficult to analyse by mass spectrometry (MS) due to its high negative charge and size. Most analytical approaches for analysis of PSA measure its degree of polymerization and monosaccharide composition, but do not address the key questions of site specificity and occupancy. Here, we developed a high-throughput LC-ESI-MS/MS glycoproteomics method to measure site-specific polysialylation of glycoproteins. This method measures site-specific PSA modification by using mild acid hydrolysis to eliminate PSA and sialic acids while leaving the glycan backbone intact, together with protease digestion followed by LC-ESI-MS/MS glycopeptide detection. PSA-modified glycopeptides are not detectable by LC-ESI-MS/MS, but become detectable after desialylation, allowing measurement of site-specific PSA occupancy. This method is an efficient analytical workflow for the study of glycoprotein polysialylation in biological and therapeutic settings. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/740928v2_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@928857org.highwire.dtl.DTLVardef@353842org.highwire.dtl.DTLVardef@a97aorg.highwire.dtl.DTLVardef@176a134_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

biochemistry↗

bioRxiv2019

PSS: An enabling QTY server for designing water-soluble α-helical transmembrane proteins

Membrane proteins, especially the -helical ones such as G-protein coupled receptors (GPCRs), are considered extremely important owing to their significant biological roles. However, their expression and purification pose difficulties because of their poor solubility in water, which seriously impedes research progress in this field. Recently, QTY method, a revolutionary code-based protein engineering approach, was developed for the purpose of producing soluble transmembrane proteins. Here we describe a web server built for QTY design and certain analyses related to it (pss.sjtu.edu.cn). Typically, the Simple Design model is expected to take only 2-4 min, and the Library Design 2-5 h, of computer time, depending on target protein size and the number of transmembrane helices. Further, we describe a protocol for using the server with both Simple and Library Design modules. Protocols for experiments based on QTY design are also included. In summary, utilization of the web server, and associated protocols, will enable QTY-based protein-engineering to be implemented in a convenient, fast, accurate, and rational manner.

bioinformatics↗

bioRxiv2019

Arabidopsis ERF109 regulates auxin transport-related genes in root development

The transcription factor ERF109 acts as a crosstalk node between jasmonic acid signaling and auxin biosynthesis by directly regulating YUC2 and ASA1 during lateral root formation in Arabidopsis. However, whether ERF109 regulates the auxin transport remains unclear. Here we report a mechanism of ERF109-mediated auxin transport in root system. Through root transcriptome comparison between erf109, wild type, and 35S:ERF109, we found that the genes PIN2 and PIN4, encoding the major membrane-based efflux carriers of auxin, were enriched in the overexpression line. In the promoters of these auxin transport genes, GCC-box cis elements were found and potentially bound by ERF109. Moreover, PID, encoding a key regulator in polar auxin transport, was found upregulated in 35S:ERF109 and down regulated in erf109. Yeast-one-hybrid and chromatin immunoprecipitation assays showed that ERF109 directly bound to the GCC-box of PIN2, PIN4, and PID. Genetic analyses with double mutants confirmed the function of ERF109 in the regulation of auxin transport in Arabidopsis roots. Taken together, our results show that ERF109 modulates auxin transport by directly regulating PIN2, PIN4 and PID. This ERF109-mediated auxin transport likely works together with ERF109-mediated auxin synthesis to establish auxin maxima for lateral root initiation.

plant biology↗

bioRxiv2019

Odorant receptors from Culex quinquefasciatus and Aedes aegypti sensitive to floral compounds

Mosquitoes rely heavily on the olfactory system to find a host for a bloodmeal, plants for a source of energy and suitable sites for oviposition. Here, we examined a cluster of 8 odorant receptors (ORs), which includes one OR, CquiOR1, previously identified to be sensitive to plant-derived compounds. We cloned 5 ORs from Culex quinquefasciatus and 2 ORs from Aedes aegypti, ie, CquiOR2, CquiOR4, CquiOR5, CquiOR84, CquiOR85, AaegOR14, and AaegOR15 and then deorphanized these receptors using the Xenopus oocyte recording system and a large panel of odorants. 2-Phenylethanol, phenethyl formate, and phenethyl propionate were the best ligands for CquiOR4 somewhat resembling the profile of AaegOR15, which gave the strongest responses to phenethyl propionate, phenethyl formate, and acetophenone. In contrast, the best ligands for CquiOR5 were linalool, PMD, and linalool oxide. CquiOR4 was predominantly expressed in antennae of nonblood fed female mosquitoes, with transcript levels significantly reduced after a blood meal. 2-Phenylethanol showed repellency activity comparable to that of DEET at 1%. RNAi experiments suggest that at least in part 2-phenylethanol-elicited repellency is mediated by CquiOR4 activation.

physiology↗

bioRxiv2019

DEET and other repellents are inhibitors of mosquito odorant receptors for oviposition attractants

In addition to its primary function as an insect repellent, DEET has many \"off-label\" properties, including a deterrent effect on attraction of gravid female mosquitoes. DEET negatively affects oviposition sites. While deorphanizing odorant receptors (ORs) using the Xenopus oocyte recording system, we have previously observed that DEET generated outward (inhibitory) currents on ORs sensitive to oviposition attractants. Here, we systematically investigated these inhibitory currents. We recorded dose-dependent outward currents elicited by DEET and other repellents on ORs from Culex quinquefasciatus, Aedes aegypti, and Anopheles gambiae. Similar responses were observed with other plant-derived and plant-inspired compounds, including methyl jasmonate and methyl dihydrojasmolate. Inward (regular) currents elicited by skatole upon activation of CquiOR21 were modulated when this oviposition attractant was coapplied with a repellent. Compounds that generate outward currents in ORs sensitive to oviposition attractants elicited inward currents in a DEET-sensitive receptor, CquiOR136. The best ligand for this receptor, methyl dihydrojasmolate, showed repellency activity, but was not as strong as DEET in our test protocol.

neuroscience↗

bioRxiv2019

A popular Indian clove-based mosquito repellent is a false economy

Insect repellents are important prophylactic tools for travelers to and populations living in endemic areas of malaria, dengue, encephalitis, and other vector-borne diseases, and the first line of defense against emerging arboviruses. However, the cost of daily applications of even the most affordable and the gold standard of insect repellents, DEET, is still high for low-income populations where repellents are needed the most. An Indian clove-based homemade recipe has been presented as a panacea. We analyzed this homemade repellent and confirmed by behavioral measurements and odorant receptor responses that eugenol is the active ingredient in this formulation. Prepared as advertised, this homemade repellent is ineffective, whereas 5X more concentrated extracts from the brand most enriched in eugenol showed moderate repellency activity against Culex quinquefasciatus and Aedes aegypti. DEET showed higher performance when compared to the 5X concentrated formulation and is available in the same market at a lower price than the cost of the ingredients to prepare the homemade formulation.

ecology↗