Biology subjects

Chen, A.

Publications and source records attributed to Chen, A..

At least 235 records · Page 13Linked to original sources

bioRxiv2020

De novo design of ACE2 protein decoys to neutralize SARS-CoV-2

There is an urgent need for the ability to rapidly develop effective countermeasures for emerging biological threats, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the ongoing coronavirus disease 2019 (COVID-19) pandemic. We have developed a generalized computational design strategy to rapidly engineer de novo proteins that precisely recapitulate the protein surface targeted by biological agents, like viruses, to gain entry into cells. The designed proteins act as decoys that block cellular entry and aim to be resilient to viral mutational escape. Using our novel platform, in less than ten weeks, we engineered, validated, and optimized de novo protein decoys of human angiotensin-converting enzyme 2 (hACE2), the membrane-associated protein that SARS-CoV-2 exploits to infect cells. Our optimized designs are hyperstable de novo proteins ([~]18-37 kDa), have high affinity for the SARS-CoV-2 receptor binding domain (RBD) and can potently inhibit the virus infection and replication in vitro. Future refinements to our strategy can enable the rapid development of other therapeutic de novo protein decoys, not limited to neutralizing viruses, but to combat any agent that explicitly interacts with cell surface proteins to cause disease.

biochemistry↗

bioRxiv2020

Small-hairpin RNAs cause target-independent microRNA dysregulation in neurons and elicit global transcriptomic changes

Small hairpin RNAs (shRNAs) allow highly efficient gene knockdown. Here we employed different shRNAs to knock down the reticulon RTN4A/NogoA in primary neurons. Depletion of NogoA correlates with altered synaptic protein composition and spontaneous neurotransmission. However, similar phenotypes are not observed upon genetic deletion of Nogo or its receptors. Step-wise introduction of mismatches in the seed region of shNogoA provides further evidence that synaptic phenotypes are NogoA-independent. RNA sequencing revealed global changes in the neuronal transcriptome of cultures transduced with the original shNogoA or closely related variants. Transcriptomic changes are shRNA seed sequence dependent, but not target-specific. Parallel sequencing of small non-coding RNAs revealed dysregulation of microRNAs. Computational analysis shows that the altered miRNA composition correlates with changes in mRNA expression and preferentially affects protein-protein networks that function at synapses. Thus, off-target effects associated with shRNAs are an inherent property, and in particular, altered miRNA composition needs careful consideration.

neuroscience↗

bioRxiv2020

Lipidome profiles of plasma microvesicles differ in experimental cerebral malaria, compared to malaria without neurological complications

Cerebral malaria (CM), a fatal complication of Plasmodium infection that affects children in sub-Saharan Africa and adults in South-East Asia, results from incompletely understood pathogenetic mechanisms, which include an excessive release of microvesicles (MV). Plasma MV levels have been found elevated in CM patients and in the experimental mouse model. We compared lipid profiles in circulating MV purified from CBA mice infected with P. berghei ANKA (PbA), which causes CM, to those from P. yoelii (Py), which does not. Here we show that plasma MV produced at the time of CM differed dramatically from those from non-CM mice, in spite of identical levels of parasitaemia. Using high-resolution LCMS, we identified over 300 lipid species within 12 lipid classes. Total lysophosphatidylethanolamine (LPE) levels were significantly lower in PbA infection compared to uninfected mice, while they were unchanged in Py MV, and lysophosphatidylcholine (LPC) was more significantly reduced in PbA mice compared to the other two groups. These results suggest, for the time, that experimental CM is characterised by specific changes in lipid composition of circulating MV, pointing towards triglycerides (TG) especially docosahexaenoic acid (DHA 22:6) containing species, phosphatidylethanolamine (PE), LPC, LPE, and diacylglycerol (DG) as potential important players in CM pathogenesis.

pathology↗

bioRxiv2020

An atlas of lamina-associated chromatin across thirteen human cell types reveals cell-type-specific and multiple subtypes of peripheral heterochromatin

Association of chromatin with lamin proteins at the nuclear periphery has emerged as a potential mechanism to coordinate cell type-specific gene expression and maintain cellular identity via gene silencing. Unlike many histone modifications and chromatin-associated proteins, lamin-associated domains (LADs) have yet to be mapped genome-wide in a diverse panel of human cell types, which has limited our understanding of the role peripheral chromatin plays in development and disease. To address this gap, we mapped LAMIN B1 (LB1) across twelve human cell types encompassing pluripotent stem cells, intermediate progenitors, and differentiated cells from all three germ layers. Integrative analyses of this atlas of peripheral chromatin with publicly available genomic data, as well as gene expression and repressive histone maps generated for this study, revealed that in all twelve cellular contexts lamin-associated chromatin is organized into at least two subtypes defined by differences in LB1 occupancy, gene expression, chromatin accessibility, transposable elements, replication timing, and radial positioning. Most genes gain or lose LB1 occupancy consistent with their cell type along developmental trajectories; however, we also identified examples where the enhancer, but not the gene body and promoter, change LAD state. Imaging of fluorescently labeled DNA in single cells validated these transitions and showed intermediate radial positioning of LADs that are gene dense, relatively accessible, and dynamic across development. This atlas represents the largest resource to date for peripheral chromatin organization studies.

developmental biology↗

bioRxiv2020

The Roles of Space and Stochasticity in Computational Simulations of Cellular Biochemistry: Quantitative Analysis and Qualitative Insights

Most of the fascinating phenomena studied in cell biology emerge from interactions among highly organized multi-molecular structures and rapidly propagating molecular signals embedded into complex and frequently dynamic cellular morphologies. For the exploration of such systems, computational simulation has proved to be an invaluable tool, and many researchers in this field have developed sophisticated computational models for application to specific cell biological questions. However it is often difficult to reconcile conflicting computational results that use different simulation approaches (for example partial differential equations versus particle-based stochastic methods) to describe the same phenomenon. Moreover, the details of the computational implementation of any particular algorithm may give rise to quantitatively or even qualitatively different results for the same set of starting assumptions and parameters. In an effort to address this issue systematically, we have defined a series of computational test cases ranging from very simple (bimolecular binding in solution) to moderately complex (spatial and temporal oscillations generated by proteins binding to membranes) that represent building blocks for comprehensive three-dimensional models of cellular function. Having used two or more distinct computational approaches to solve each of these test cases with consistent parameter sets, we generally find modest but measurable differences in the solutions of the same problem, and a few cases where significant deviations arise. We discuss the strengths and limitations of commonly used computational approaches for exploring cell biological questions and provide a framework for decision-making by researchers wishing to develop new models for cell biology. As computational power and speed continue to increase at a remarkable rate, the dream of a fully comprehensive computational model of a living cell may be drawing closer to reality, but our analysis demonstrates that it will be crucial to evaluate the accuracy of such models critically and systematically.

systems biology↗

bioRxiv2020

Spatially displaced excitation contributes to the encoding of interrupted motion by the retinal direction-selective circuit

Spatially distributed excitation and inhibition collectively shape a visual neurons receptive field (RF) properties. In the direction-selective circuit of the mammalian retina, the role of strong null-direction inhibition of On-Off direction-selective ganglion cells (ON-OFF DSGCs) on their direction selectivity is well-studied. However, how excitatory inputs influence the On-Off DSGCs visual response is underexplored. Here, we report that On-Off DSGCs have a spatially displaced glutamatergic receptive field along their preferred-null motion axis. This displaced receptive field contributes to DSGC null-direction spiking during interrupted motion trajectories. Theoretical analyses indicate that population responses during interrupted motion may help populations of On-Off DSGCs signal the spatial location of moving objects in complex, naturalistic visual environments. Our study highlights that the direction-selective circuit exploits separate sets of mechanisms under different stimulus conditions, and these mechanisms may help encode multiple visual features.

neuroscience↗

bioRxiv2020

Single-cell regulatory landscape and disease vulnerability map of adult Macaque cortex

Single cell approaches have increased our knowledge about the cell type composition of the non-human primate (NHP), but a detailed characterization of area-specific regulatory features remains outstanding. We generated single-cell chromatin accessibility (single-cell ATAC) and transcriptomic data of 358,237 cells from prefrontal cortex (PFC), primary motor cortex (M1) and primary visual cortex (V1) of adult cynomolgus monkey brain, and integrated this dataset with Stereo-seq (Spatio-Temporal Enhanced REsolution Omics-sequencing) of the corresponding cortical areas to assign topographic information to molecular states. We identified area-specific chromatin accessible sites and their targeted genes, including the cell type-specific transcriptional regulatory network associated with excitatory neurons heterogeneity. We reveal calcium ion transport and axon guidance genes related to specialized functions of PFC and M1, identified the similarities and differences between adult macaque and human oligodendrocyte trajectories, and mapped the genetic variants and gene perturbations of human diseases to NHP cortical cells. This resource establishes a transcriptomic and chromatin accessibility combinatory regulatory landscape at a single-cell and spatially resolved resolution in NHP cortex.

neuroscience↗

bioRxiv2020

Effects of regulatory network organization and environment on PmrD connector activity and polymyxin resistance in Klebsiella pneumoniae and Escherichia coli

Polymyxins are a class of cyclic peptides with antimicrobial activity against Gram-negative bacteria. Resistance to these compounds is often mediated by pathways that also confer resistance to host antimicrobial peptides. In Enterobacteriaceae, the PhoQ/PhoP and PmrB/PmrA two-component systems regulate many of the genes associated with these resistance mechanisms. In K. pneumoniae, spontaneous polymyxin resistance is frequently acquired through inactivation of the gene mgrB, which encodes a negative regulator of PhoQ. However, this resistance mechanism has not been reported in other genera of Enterobacteriaceae, despite the presence of mgrB among many members of this family. In addition, the frequency of developing spontaneous resistance to the antimicrobial peptide polymyxin through chromosomal mutations is much higher in Klebsiella compared to Salmonella or E. coli. Here we show that in K. pneumoniae, PmrD is not required for polymyxin resistance arising from inactivation of mgrB. In addition, we show that in E. coli, the protein PmrD can activate PmrA under certain conditions. Our results suggest that the importance of PmrD connector activity in polymyxin resistance depends on both the network organization and on the environmental conditions associated with PmrB stimulation.

microbiology↗

bioRxiv2020

Epistatic interactions between PHOTOPERIOD-1, CONSTANS 1 and CONSTANS 2 modulate the photoperiodic response in wheat

In Arabidopsis, CONSTANS (CO) integrates light and circadian clock signals to promote flowering under long days (LD). In the grasses, a duplication generated two paralogs designated as CONSTANS 1 (CO1) and CONSTANS 2 (CO2). Here we show that in tetraploid wheat plants grown under LD, combined loss-of-function mutations in the A and B-genome homeologs of CO1 and CO2 (co1 co2) result in a small (3 d) but significant (P<0.0001) acceleration of heading time both in PHOTOPERIOD1 (PPD1) sensitive (Ppd-A1b, functional ancestral allele) and insensitive (Ppd-A1a, functional dominant allele) backgrounds. Under short days (SD), co1 co2 mutants headed 13 d earlier than the wild type (P<0.0001) in the presence of Ppd-A1a. However, in the presence of Ppd-A1b, spikes from both genotypes failed to emerge by 180 d. These results indicate that CO1 and CO2 operate mainly as weak heading time repressors in both LD and SD. By contrast, in ppd1 mutants with loss-of-function mutations in both PPD1 homeologs, the wild type Co1 allele accelerated heading time >60 d relative to the co1 mutant allele under LD. We detected significant genetic interactions among CO1, CO2 and PPD1 genes on heading time, which were reflected in complex interactions at the transcriptional and protein levels. Loss-of-function mutations in PPD1 delayed heading more than combined co1 co2 mutations and, more importantly, PPD1 was able to perceive and respond to differences in photoperiod in the absence of functional CO1 and CO2 genes. Similarly, CO1 was able to accelerate heading time in response to LD in the absence of a functional PPD1. Taken together, these results indicate that PPD1 and CO1 are able to respond to photoperiod in the absence of each other, and that interactions between these two photoperiod pathways at the transcriptional and protein levels are important to fine-tune the flowering response in wheat. Author summaryAn understanding of the mechanisms involved in the regulation of wheat heading time is required to engineer more productive varieties better adapted to new or changing environments. A large proportion of wheats natural variation in heading time is determined by differences in genes controlling the photoperiodic response. In this study, we show that the wheat PHOTOPERIOD1 (PPD1) gene has a stronger effect on heading time than CONSTANS1 (CO1) and CO2 in the regulation of the photoperiodic response, and that complex genetic interactions among these genes are important to fine-tune heading time. Using loss-of-function mutants for both CO1 and CO2, we demonstrate that these genes are not required for PPD1 to perceive differences in photoperiod and regulate heading time. Similarly, we show that in the absence of PPD1, CO1 can accelerate heading time more than 60 days in response to long days. Our results indicate that each of these two wheat photoperiod pathways can respond to differences in photoperiod even in the absence of the other one. Differences in the relative importance of these two pathways and in their epistatic interactions have contributed to the diversity of photoperiodic responses observed in different grass species.

plant biology↗

bioRxiv2020

Redundant cytokine requirement for intestinal microbiota-induced Th17 cell differentiation in draining lymph nodes

Differentiation of intestinal T helper 17 (Th17) cells, which contribute to mucosal barrier protection from invasive pathogens, is dependent on colonization with distinct commensal bacteria. Segmented filamentous bacteria (SFB) are sufficient to support Th17 cell differentiation in mouse, but the molecular and cellular requirements for this process remain incompletely characterized. Here we show that intestine-draining mesenteric lymph nodes (MLN) are the dominant site of SFB-induced intestinal Th17 cell differentiation. Subsequent migration of these cells to the intestinal lamina propria is dependent on their up-regulation of integrin {beta}7. Stat3-dependent induction of ROR{gamma}t, the Th17 cell-specifying transcription factor, largely depends on IL-6, but signaling through the receptors for IL-21 and IL-23 can compensate for absence of IL-6 to promote SFB-directed Th17 cell differentiation. These results indicate that redundant cytokine signals guide commensal microbe-dependent Th17 cell differentiation in the MLN and accumulation of the cells in the lamina propria.

immunology↗

bioRxiv2020

Revealing heritability missed by single locus analyses by examining epistasis in mouse chromosome substitution strains

The genetic contribution of additive versus non-additive (epistatic) effects in the regulation of complex traits is unclear. While genome-wide association studies typically ignore gene-gene interactions, in part because of the lack of statistical power for detecting them, mouse chromosome substitution strains (CSSs) represent an alternate and powerful model for detecting epistasis given their limited allelic variation. Therefore, we utilized CSSs to identify and map both additive and epistatic loci that regulate a range of hematologic- and metabolism-related traits, as well as hepatic gene expression. Quantitative trait loci (QTLs) were identified using a CSS-based backcross strategy involving the segregation of variants on the A/J-derived substituted chromosomes 4 and 6 on an otherwise C57BL/6J genetic background. In the liver transcriptomes of offspring from this cross, we identified and mapped additive QTLs regulating the hepatic expression of 768 genes, and epistatic QTL pairs for 519 genes. Similarly, we identified additive QTLs for fat pad weight, platelets, and the percentage of granulocytes in blood, as well as epistatic QTL pairs controlling the percentage of lymphocytes in blood and red cell distribution width. The variance attributed to the epistatic QTL pairs was approximately equal to that of the additive QTLs; however, the SNPs in the epistatic QTL pairs that accounted for the largest variances were undetected in our single locus association analyses. These findings highlight the need to account for epistasis in association studies, and more broadly demonstrate the importance of identifying genetic interactions to understand the complete genetic architecture of complex traits.

genetics↗

bioRxiv2020

Generating functional protein variants with variational autoencoders

The design of novel proteins with specified function and controllable biochemical properties is a longstanding goal in bio-engineering with potential applications across medicine and nanotechnology. The vast expansion of protein sequence databases over the last decades provides an opportunity for new approaches which seek to learn the sequence-function relationship directly from natural sequence variation. Advances in deep generative models have led to the successful modelling of diverse kinds of high-dimensional data, from images to molecules, allowing the generation of novel, realistic samples. While deep models trained on protein sequence data have been shown to learn biologically meaningful representations helpful for a variety of downstream tasks, their potential for direct use in protein engineering remains largely unexplored. Here we show that variational autoencoders trained on a dataset of almost 70000 luciferase-like oxidoreductases can be used to generate novel, functional variants of the luxA bacterial luciferase. We propose separate VAE models to work with aligned sequence input (MSA VAE) and raw sequence input (AR-VAE), and offer evidence that while both are able to reproduce patterns of amino acid usage characteristic of the family, the MSA VAE is better able to capture long-distance dependencies reflecting the influence of 3D structure. To validate the practical utility of the models, we used them to generate variants of luxA whose function was tested experimentally. As further evidence of the practicality of these methods for design, we showed that conditional variants of both models could be used to increase the solubility of luxA without disrupting function. Altogether 18/24 of the variants generated using the AR-VAE and 21/23 variants generated using the MSA VAE retained some luminescence activity, despite containing as many as 35 differences relative to any training set sequence. These results demonstrate the feasibility of using deep generative models to explore the space of possible protein sequences and generate useful variants, providing a method complementary to rational design and directed evolution approaches.

bioinformatics↗

bioRxiv2020

Oxytocin differentially modulates amygdala responses during top-down and bottom-up aversive anticipation

The ability to successfully regulate negative emotions such as fear and anxiety is vital for mental health. The neuropeptide oxytocin (OXT) acts as important modulator of emotion regulation, as reflected by reduced amygdala responses but increased amygdala-prefrontal cortex (PFC) functional connectivity in response to threatening stimuli. The present randomized, between-subject, placebo (PLC)-controlled pharmacological study combined intranasal administration of OXT with functional MRI during an explicit (cognitive) emotion regulation (i.e. distancing reappraisal) paradigm in 65 healthy male participants to investigate the modulatory effects of OXT on both bottom-up and top-down emotion regulation. OXT attenuated the activation in posterior insular cortex and amygdala during anticipation of top-down regulation of predictable threat stimuli in participants with high trait anxiety, providing evidence to support the anxiolytic action of OXT. In contrast, OXT enhanced amygdala activity during bottom-up anticipation of an unpredictable threat stimulus in participants with low trait anxiety. OXT may thus facilitate top-down goal-directed attention by attenuating amygdala activity in high anxiety individuals, while promote bottom-up attention/vigilance to unexpected threat by enhancing anticipatory amygdala activity in low anxiety individuals. The opposite effects of OXT on anticipatory amygdala activation in high versus low anxiety individuals may suggest a baseline anxiety level dependent mechanism via which OXT promotes optimal levels of amygdala activation during the anticipation of an imminent threat. OXT may thus have the potential to promote an adaptive balance between bottom-up and top-down attention systems depending on individual levels of pre-treatment trait anxiety levels.

neuroscience↗

bioRxiv2020

Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods

Enteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses are shed in high numbers, have low infectious dose, and may remain infectious for weeks in the environment and food. While numerous viral survival studies have been conducted in fresh fruits and produce, limited information is available regarding viral survival and transmission in low moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during long-term storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR). We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that foodborne viruses can persist for long-time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% inactivation can be achieved for FCV, MNV, and HAV in chocolate, the inactivation efficiency diminishes to approximately 90% in pistachios and 70% in cereal. AOP treatment could therefore be a good candidate for the elimination of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment. ImportanceLow moisture foods have been increasingly recognized as important vehicles of foodborne pathogens. In the present study, we demonstrated that foodborne viruses remain infectious during long-term storage on select low moisture foods. In addition, we evaluated the efficacy of an advanced oxidative process in the inactivation of foodborne viruses in low moisture foods. This research will help increase the safety of low moisture foods and reduce the number of foodborne illnesses due to contaminated products.

microbiology↗

bioRxiv2020

CoolMPS™: Advanced massively parallel sequencing using antibodies specific to each natural nucleobase

Massively parallel sequencing (MPS) on DNA nanoarrays provides billions of reads at relatively low cost and enables a multitude of genomic applications. Further improvement in read length, sequence quality and cost reduction will enable more affordable and accurate comprehensive health monitoring tests. Currently the most efficient MPS uses dye-labeled reversibly terminated nucleotides (RTs) that are expensive to make and challenging to incorporate. Furthermore, a part of the dye-linker (scar) remains on the nucleobase after cleavage and interferes with subsequent sequencing cycles. We describe here the development of a novel MPS chemistry (CoolMPS) utilizing unlabeled RTs and four natural nucleobase-specific fluorescently labeled antibodies with fast (30 sec) binding. We implemented CoolMPS on MGIs PCR-free DNBSEQ MPS platform using arrays of 200nm DNA nanoballs (DNBs) generated by rolling circle replication and demonstrate 3-fold improvement in signal intensity and elimination of scar interference. Single-end 100-400 base and pair-end 2x150 base reads with high quality were readily generated with low out-of-phase incorporation. Furthermore, DNBs with less than 50 template copies were successfully sequenced by strong-signal CoolMPS with 3-times higher accuracy than in standard MPS. CoolMPS chemistry based on natural nucleobases has potential to provide longer, more accurate and less expensive MPS reads, including highly accurate "4-color sequencing" on the most efficient dye-crosstalk-free 2-color imagers with an estimated sequencing error rate of 0.00058% (one error in 170,000 base calls) in a proof-of-concept demonstration.

genomics↗

bioRxiv2020

Common postzygotic mutational signature in multiple healthy adult tissues related to embryonic hypoxia

Postzygotic mutations are acquired in all of the normal tissues throughout an individuals lifetime and hold clues for identifying mutagenesis causing factors. The process and underlying mechanism of postzygotic mutations in normal tissues is still poorly understood. In this study, we investigated postzygotic mutation spectra in healthy individuals by optimized ultra-deep exome sequencing of time series samples from the same volunteer and samples from different individuals. In cells of blood, sperm, and muscle, we resolved three common types of mutational signature. Two of them are known to represent clock-like mutational processes, and their proportions in mutation profiles associated with polymorphisms of epigenetic regulation genes, suggesting the contribution of personal genetic backgrounds to underlying biological process. Notably, the third signature, characterized by C>T transitions at GpCpN sites, tends to be a feature of diverse normal tissues. Mutations of this type were likely to occur early in embryo development even before the tissue differentiation, as indicated by their relatively high allele frequencies, sharing variants between multiple tissues, and lacking of age-related accumulation. Almost all tumors shown in public datasets did not have this signature detected except for 19.6% of clear cell renal cell carcinoma samples, which featured by activation of the hypoxia-induced signaling pathway. Moreover, in vitro activation of HIF signaling pathway successfully introduced the corresponding mutation profile of this signature in a culture-expanded human embryonic stem cell line. Therefore, embryonic hypoxia may explain this novel signature across multiple normal tissues. Our study suggest hypoxic conditions in the early stage of embryo development may be a crucial factor for the C>T transitions at GpCpN sites and individual genetic background also related to shaping human postzygotic mutation profiles.

genetics↗

bioRxiv2020

Remote-controlled insect navigation using plasmonic nanotattoos

Developing insect cyborgs by integrating external components (optical, electrical or mechanical) with biological counterparts has a potential to offer elegant solutions for complex engineering problems.1 A key limiting step in the development of such biorobots arises at the nano-bio interface, i.e. between the organism and the nano implant that offers remote controllability.1,2 Often, invasive procedures are necessary that tend to severely compromise the navigation capabilities as well as the longevity of such biorobots. Therefore, we sought to develop a non-invasive solution using plasmonic nanostructures that can be photoexcited to generate heat with spatial and temporal control. We designed a nanotattoo using silk that can interface the plasmonic nanostructures with a biological tissue. Our results reveal that both structural and functional integrity of the biological tissues such as insect antenna, compound eyes and wings were preserved after the attachment of the nanotattoo. Finally, we demonstrate that insects with the plasmonic nanotattoos can be remote controlled using light and integrated with functional recognition elements to detect the chemical environment in the region of interest. In sum, we believe that the proposed technology will play a crucial role in the emerging fields of biorobotics and other nano-bio applications.

bioengineering↗

bioRxiv2020

Sexually divergent effects of social dominance on chronic stress outcomes in mice

BackgroundSex and social context are two major factors in the development of depression and other stress-related disorders. However, few studies of the effects of stress on rodent behavior and physiology have investigated social context and fewer still have assessed the possibility of sex-specific effects of social context. MethodsWe assessed social dominance of group-living mice during several days of monitoring using a high-throughput automated behavioral tracking system. We then exposed groups from each sex to a three-week chronic mild stress (CMS) procedure, followed by a behavioral test battery. Finally, we used principle component analysis and post-hoc tests to explore the sources of variance in the behavioral outcome data. ResultsWe found stable hierarchies in both sexes, however social dominance in males exhibited several additional associations with behaviors related to locomotion and exploration that were not seen in females. Crucially, pre-stress social dominance status was associated with opposing outcomes on multiple behavioral readouts between the two sexes following CMS. In particular, subordinate male mice and dominant female mice appeared more responsive to the environmental challenge, as observed in anxiety-like and locomotor behaviors. ConclusionsThis work demonstrates that sex differences interact with preexisting social dominance status to alter the effects of chronic stress. It highlights the importance of understanding the interplay between sex and social context and its contribution to individual differences in stress response.

neuroscience↗