Biology subjects

Joseph, J.

Publications and source records attributed to Joseph, J..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

Development and Optimisation of in vitro Sonodynamic Therapy for Glioblastoma

BackgroundSonodynamic therapy (SDT) is currently on critical path for glioblastoma therapeutics. However, the molecular mechanisms underlying the therapeutic functions of SDT remain enigmatic due to the lack of intricately optimised instrumentation capable of modulating SDT delivery in vitro. We established and validated an automated in vitro SDT system and assessed its SDT efficacy. MethodsAn automated in vitro SDT system was established and validated to allow the application and mapping of focused ultrasound fields under varied acoustic exposure conditions and setup configurations. Ultrasound field simulations were performed to assess the acoustic energy exposure. Systematic in vitro investigations were performed to optimise ultrasound frequency, intensity, plate base material, thermal effect, and the integration of live cells. ResultsIn the presence of 5-ALA, focused ultrasound induces apoptotic cell death in primary patient-derived glioma cells with concurrent upregulation of intracellular reactive oxygen species. Intriguingly, primary glioma stem neurospheres also exhibit remarkably reduced 3D growth upon SDT exposure. Further, ultrasound field simulations performed established acoustic field distribution and the impact of acoustic standing waves within the well-plates. ConclusionsThe optimised in vitro SDT system and associated ultrasound field simulations establish the basis for further understanding of SDT and its therapeutic potentials in cancer.

bioengineering↗

bioRxiv2023

Mammalian protein-coding genes exhibit widespread beneficial mutations that are not adaptive

Mutations can be beneficial by bringing innovation to their bearer, allowing them to adapt to environmental change. These mutations are typically unpredictable since they respond to an unforeseen change in the environment. However, mutations can also be beneficial because they are simply restoring a state of higher fitness that was lost due to genetic drift in a stable environment. In contrast to adaptive mutations, these beneficial non-adaptive mutations can be predicted if the underlying fitness landscape is stable and known. The contribution of such non-adaptive mutations to molecular evolution has been widely neglected mainly because their detection is very challenging. We have here reconstructed protein-coding-gene fitness landscapes shared between mammals, using mutation-selection models and a multi-species alignments across 87 mammals. These fitness landscapes have allowed us to predict the fitness effect of polymorphisms found in 28 mammalian populations. Using methods that quantify selection at the population level, we have confirmed that beneficial non-adaptive mutations are indeed positively selected in extant populations. Our work confirms that deleterious substitutions are accumulating in mammals and are being reverted, generating a balance in which genomes are damaged and restored simultaneously at different loci. We observe that beneficial non-adaptive mutations represent between 15% and 45% of all beneficial mutations in 24 of 28 populations analyzed, suggesting that a substantial part of ongoing positive selection is not driven solely by adaptation to environmental change in mammals. Significance statementThe extent to which adaptation to changing environments is shaping genomes is a central question in molecular evolution. To quantify the rate of adaptation, population geneticists have typically used signatures of positive selection. However, mutations restoring an ancestral state of higher fitness lost by genetic drift are also positively selected, but they do not respond to a change in the environment. In this study, we have managed to distinguish beneficial mutations that are due to changing environments and those that are restoring pre-existing functions in mammals. We show that a substantial proportion of beneficial mutations cannot be interpreted as adaptive.

evolutionary biology↗

bioRxiv2023

PhylteR: efficient identification of outlier sequences in phylogenomic datasets

In phylogenomics, incongruences between gene trees, resulting from both artifactual and biological reasons, can decrease the signal-to-noise ratio and complicate species tree inference. The amount of data handled today in classical phylogenomic analyses precludes manual error detection and removal. However, a simple and efficient way to automate the identification of outliers from a collection of gene trees is still missing. Here, we present PhylteR, a method that allows a rapid and accurate detection of outlier sequences in phylogenomic datasets, i.e. species from individual gene trees that do not follow the general trend. PhylteR relies on DISTATIS, an extension of multidimensional scaling to 3 dimensions to compare multiple distance matrices at once. In PhylteR, these distance matrices extracted from individual gene phylogenies represent evolutionary distances between species according to each gene. On simulated datasets, we show that PhylteR identifies outliers with more sensitivity and precision than a comparable existing method. We also show that PhylteR is not sensitive to ILS-induced incongruences, which is a desirable feature. On a biological dataset of 14,463 genes for 53 species previously assembled for Carnivora phylogenomics, we show (i) that PhylteR identifies as outliers sequences that can be considered as such by other means, and (ii) that the removal of these sequences improves the concordance between the gene trees and the species tree. Thanks to the generation of numerous graphical outputs, PhylteR also allows for the rapid and easy visual characterisation of the dataset at hand, thus aiding in the precise identification of errors. PhylteR is distributed as an R package on CRAN and as containerized versions (docker and singularity).

evolutionary biology↗

bioRxiv2022

Decoding Proteoforms with Single Acid Resolution Using a Sub-nanometer Diameter Pore

When a denatured protein isoform (i.e., a proteoform) immersed in electrolyte is impelled by an electric field through a sub-nanometer-diameter pore (i.e., a sub-nanopore) spanning a thin membrane, the sequence of amino acid (AA) residues constituting the proteoform can be directly "read" one at a time by measuring fluctuations in the electrolytic current. Corroborating this assertion, an analysis of the pore current with molecular dynamic (MD) simulations reveals that the fluctuations are correlated to the sequence of AA volumes, the water in the pore and affected by the acid mobility. After alignment to account for variations in the acid mobility, the simulated pore current is nearly perfectly correlated to the pattern of empirical fluctuations. To prove out the prospects for decoding proteoforms this way, site-specific post-translational modifications (PTMs) and point mutations in amyloid-beta (A{beta} 1-42) are analyzed with a sub-nanopore assay. The results show that single acids can be resolved in proteoforms with a dynamic range limited by the size of phenylalanine and glycine. With this sensitivity and single acid resolution, the sequence of a scrambled variant of A{beta} 1-42 was discriminated with a p-value < 10-5.

biophysics↗

bioRxiv2022

Post-vaccination Omicron infections induce broader immunity across antigenic space than prototype mRNA COVID-19 booster vaccination or primary infection

The rapid emergence of new SARS-CoV-2 variants challenges vaccination strategies. Here, we measured antigenic diversity among variants and interpreted neutralizing antibody responses following single and multiple exposures in longitudinal infection and vaccine cohorts. Antigenic cartography using primary infection antisera showed that BA.2, BA.4/BA.5, and BA.2.12.1 are distinct from BA.1 and closer to the Beta cluster. Three doses of an mRNA COVID-19 vaccine increased breadth to BA.1 more than to BA.4/BA.5 or BA.2.12.1. Omicron BA.1 post-vaccination infection elicited antibody landscapes characterized by broader immunity across antigenic space than three doses alone, although with less breadth than expected to BA.2.12.1 and BA.4/BA.5. Those with Omicron BA.1 infection after two or three vaccinations had similar neutralizing titer magnitude and antigenic breadth. Accounting for antigenic differences among variants of concern when interpreting neutralizing antibody titers aids understanding of complex patterns in humoral immunity and informs selection of future COVID-19 vaccine strains.

microbiology↗

bioRxiv2021

A novel innate pathogen sensing strategy involving ubiquitination of bacterial surface proteins

Sensing of pathogens by ubiquitination is critical for maintaining cytosolic sanctity. However, universal ubiquitination targets on bacteria, especially of proteinaceous origin, remain unidentified. Here, we unveil a novel strategy, involving recognition of degron-like motifs for identification of first protein-based ubiquitination substrates on phylogenetically distinct bacteria. Such motifs can form a new class of intra-cytosolic pathogen associated molecular patterns (PAMPs) as their incorporation enables identification of non-ubiquitin targets by host Ub-ligases. We find SCFFBW7 E3-ligase, supported by the regulatory kinase, GSK3{beta}, is crucial for effective pathogen detection and clearance. This may explain the enhanced risk of infections in Chronic Lymphocytic Leukaemia patients bearing FBXW7 mutations. We conclude that exploitation of such ubiquitous pathogen sensing strategy allows conservation of cellular resources and boost anti-microbial immunity. One Sentence SummaryUbiquitination of bacterial surface proteins fosters sensing and clearance of diverse pathogens

microbiology↗

bioRxiv2021

Kinetic interplay between droplet maturation and coalescence modulates shape of aged protein condensates

Biomolecular condensates formed by the process of liquid-liquid phase separation (LLPS) play diverse roles inside cells, from spatiotemporal compartmentalisation to speeding up chemical reactions. Upon maturation, the liquid-like properties of condensates, which underpin their functions, are gradually lost, eventually giving rise to solid-like states with potential pathological implications. Enhancement of inter-protein interactions is one of the main mechanisms suggested to trigger the formation of solid-like condensates. To gain a molecular-level understanding of how the accumulation of stronger interactions among proteins inside condensates affect the kinetic and thermodynamic properties of biomolecular condensates, and their shapes over time, we develop a tailored coarse-grained model of proteins that transition from establishing weak to stronger inter-protein interactions inside condensates. Our simulations reveal that the fast accumulation of strongly binding proteins during the nucleation and growth stages of condensate formation results in aspherical solid-like condensates. In contrast, when strong inter-protein interactions appear only after the equilibrium condensate has been formed, or when they accumulate slowly over time, with respect to the time needed for droplets to fuse and grow, spherical solid-like droplets emerge. By conducting atomistic potential-of-mean-force simulations of NUP-98 peptides--prone to forming inter-protein {beta}-sheets--we observe that formation of inter-peptide {beta}-sheets increases the strength of the interactions consistently with the loss of liquid-like condensate properties we observe at the coarse-grained level. Overall, our work aids in elucidating fundamental molecular, kinetic, and thermodynamic mechanisms linking the rate of change in protein interaction strength to condensate shape and maturation during ageing.

biophysics↗

bioRxiv2021

Nup358 regulates remodelling of ER-mitochondrial contact sites and autophagy

The contact sites between ER and mitochondria regulate several cellular processes including inter-organelle lipid transport, calcium homeostasis and autophagy. However, the mechanisms that regulate the dynamics and functions of these contact sites remain unresolved. We show that annulate lamellae (AL), a relatively unexplored subcellular structure representing subdomains of ER enriched with a subset of nucleoporins, are present at ER-mitochondria contact sites (ERMCS). Depletion of one of the AL-resident nucleoporins, Nup358, results in increased contacts between ER and mitochondria. Mechanistically, Nup358 modulates ERMCS dynamics by restricting mTORC2/Akt signalling. Our results suggest that growth factor-mediated remodelling of ERMCS depends on a reciprocal binding of Nup358 and mTOR to the ERMCS tethering complex consisting of VAPB and PTPIP51. Furthermore, Nup358 also interacts with IP3R, an ERMCS-enriched Ca2+ channel, and controls Ca2+ release from the ER. Consequently, depletion of Nup358 leads to elevated cytoplasmic Ca2+ and autophagy via activation of Ca2+/CaMKK2/AMPK axis. Our study thus uncovers a novel role for AL, particularly for Nup358, in regulating mTORC2-mediated ERMCS remodelling and Ca2+-directed autophagy, possibly via independent mechanisms.

cell biology↗

bioRxiv2021

Kinetic modelling of β-cell metabolism reveals control points in the insulin-regulating pyruvate cycling pathways

Insulin, a key hormone in the regulation of glucose homeostasis, is secreted by pancreatic {beta}-cells in response to elevated glucose levels. Insulin is released in a biphasic manner in response to glucose metabolism in {beta}-cells. The first phase of insulin secretion is triggered by an increase in the ATP:ADP ratio; the second phase occurs in response to both a rise in ATP:ADP as well as other key metabolic signals, including a rise in the NADPH:NADP+ ratio. Experimental evidence indicates that pyruvate-cycling pathways play an important role in the elevation of the NADPH:NADP+ ratio in response to glucose. In this work we developed a kinetic model for the tricarboxylic acid cycle and pyruvate cycling pathways. We successfully validated our model against recent experimental observations and performed local and global sensitivity analysis to identify key regulatory interactions in the system. The model predicts that the dicarboxylate carrier (DIC) and pyruvate transporter (PYC) are the most important regulators of pyruvate cycling and NADPH production. In contrast, our analysis showed that variation in the pyruvate carboxylase (PC) flux was compensated by a response in the activity of mitochondrial isocitrate dehydrogenase (ICDm) resulting in minimal effect on overall pyruvate cycling flux. The model predictions suggest starting points for further experimental investigation, as well as potential drug targets for treatment of type 2 diabetes.

systems biology↗

bioRxiv2020

Design of a highly thermotolerant, immunogenic SARS-CoV-2 spike fragment

Virtually all SARS-CoV-2 vaccines currently in clinical testing are stored in a refrigerated or frozen state prior to use. This is a major impediment to deployment in resource-poor settings. Several use viral vectors or mRNA. In contrast to protein subunit vaccines, there is limited manufacturing expertise for these novel, nucleic acid based modalities, especially in the developing world. Neutralizing antibodies, the clearest known correlate of protection against SARS-CoV-2, are primarily directed against the Receptor Binding Domain (RBD) of the viral spike protein. We describe a monomeric, glycan engineered RBD protein fragment that is expressed at a purified yield of 214mg/L in unoptimized, mammalian cell culture and in contrast to a stabilized spike ectodomain, is tolerant of exposure to temperatures as high as 100{degrees}C when lyophilized, upto 70{degrees}C in solution and stable for over four weeks at 37{degrees}C. In prime:boost guinea pig immunizations, when formulated with the MF59 like adjuvant AddaVax, the RBD derivative elicited neutralizing antibodies with an endpoint geometric mean titer of ~415 against replicative virus, comparing favourably with several vaccine formulations currently in the clinic. These features of high yield, extreme thermotolerance and satisfactory immunogenicity suggest that such RBD subunit vaccine formulations hold great promise to combat COVID-19.

biophysics↗

bioRxiv2020

DNA-based nanocarriers to enhance the optoacoustic contrast of tumors in vivo

Optoacoustic tomography (OT) enables non-invasive deep tissue imaging of optical contrast at high spatio-temporal resolution. The applications of OT in cancer imaging often rely on the use of molecular imaging contrast agents based on near infrared dyes to enhance contrast at the tumor site. While these agents afford excellent biocompatibility and minimal toxicity, they present limited optoacoustic signal generation capability and rapid renal clearance, which can impede their tumor imaging efficacy. In this work, a synthetic strategy to overcome these limitations utilizing biodegradable DNA-based nanocarrier (DNA-NC) platforms is introduced. DNA-NCs enable the incorporation of near infrared dyes (in this case, IRDye 800CW) at precise positions to enable fluorescence quenching and maximize optoacoustic signal generation. Furthermore, these DNA-NCs show a prolonged blood circulation compared to the native fluorophores, facilitating tumor accumulation by the Enhanced Permeability and Retention (EPR) effect. In vivo imaging of tumor xenografts in mice following intravenous administration of DNA-NCs revealed enhanced OT signals at 24h when compared to free fluorophores, indicating promise for this method to enhance the optoacoustic signal generation capability and tumor uptake of clinically relevant near infrared dyes.

bioengineering↗

bioRxiv2020

Green tea and Spirulina extracts inhibit SARS, MERS, and SARS-2 spike pseudotyped virus entry in vitro

Coronaviruses (CoVs) infect a wide range of animals and birds. Their tropism is primarily determined by the ability of the spike (S) protein to bind to a host cell surface receptor. The rapid outbreak of emerging novel coronavirus, SARS-CoV 2 in China inculcates the need for the development of hasty and effective intervention strategies. Medicinal plants and natural compounds have been traditionally used to treat viral infections. Here, we generated VSV based pseudotyped viruses (pvs) of SARS-, MERS-, and SARS-2 CoVs to screen entry inhibitors from natural products. In the first series of experiments, we demonstrated that pseudotyped viruses specifically bind on their receptors and enter into the cells. SARS and MERS polyclonal antibodies neutralize SARSpv and SARS-2pv, and MERSpv respectively. Incubation of soluble ACE2 inhibited entry of SARS and SARS-2 pvs but not MERSpv. In addition, expression of ACE2 and DPP4 in non-permissive BHK21 cells enabled infection by SARSpv, SARS-2pv, and MERSpv respectively. Next, we showed the antiviral properties of known enveloped virus entry inhibitors, Spirulina and Green tea extracts against CoVpvs. SARSpv, MERSpv, and SARS-2pv entry were blocked with higher efficiency when preincubated with either green tea or spirulina extracts. Green tea provided a better inhibitory effect than the spirulina extracts by binding to the S1 domain of spike and blocking the interaction of spike with its receptor. Further studies are required to understand the exact mechanism of viral inhibition. In summary, we demonstrate that pseudotyped virus is an ideal tool for screening viral entry inhibitors. Moreover, spirulina and green tea could be promising antiviral agents against emerging viruses.

microbiology↗

bioRxiv2020

Connexin 43 hemichannels mediate spatial and temporal disease spread in ALS

Connexin 43 (Cx43) gap junctions and hemichannels mediate astrocyte intercellular communication in the central nervous system under normal conditions and may contribute to astrocyte-mediated neurotoxicity in amyotrophic lateral sclerosis (ALS). Here we show that astrocyte-specific knockout of Cx43 in a mouse model of ALS slows disease progression both spatially and temporally, provides motor neuron (MN) protection, and improves survival. In human ALS tissues and biofluids, we observe that higher levels of Cx43 correlate with accelerated disease progression. Using human iPSC-derived astrocytes (hiPSC-A) from both familial and sporadic ALS, we show that Cx43 is upregulated and that Cx43-hemichannels are enriched at the astrocyte membrane. We then demonstrate that the pharmacological blockade of Cx43-hemichannels in ALS astrocytes, during a specific temporal window, provides neuroprotection of hiPSC-MN and reduces ALS astrocyte-mediated neuronal hyperexcitability. Our data identify Cx43 hemichannels as novel conduits of astrocyte-mediated disease progression and a pharmacological target for disease-modifying ALS therapies.

neuroscience↗

bioRxiv2019

An NMDA-R mediated short-term memory resistant to anesthesia in adult Danio rerio

Memory in animals is labile in the early phase post-training. Memory in the early phase has been shown to be disrupted by treatments such as electroconvulsive shock or cold-shock (Quinn and Dudai, 1976). Using hypothermic shock and other pharmacological interventions, the various underlying memory pathways in Drosophila can be identified as an immediate short-lasting anesthesia sensitive memory and a delayed anesthesia resistant memory which is followed by a more stable protein synthesis dependent long-term memory (Margulies et al., 2005). In another ectothermic animal, Danio rerio, a popular vertebrate model, we ask if such a memory component exists which is sensitive to hypothermic disruption. To test this, we developed a fear conditioning assay with a green light at the bottom of the tank as the conditioned stimulus (CS) and electric shock as the unconditioned stimulus (US). We also standardized a cold anesthesia protocol in adult zebrafish to induce stage V anesthesia. The learning/memory was found to be NMDA-R mediated. Cold anesthesia as well as tricaine mediated anesthesia did not significantly affect the early-acting memory trace induced by a fear-conditioning protocol in adult zebrafish. We suggest future directions to tease out the underlying memory components in the early phase of memory in zebrafish.

neuroscience↗

bioRxiv2019

Reducing Unintentional Duplicate Orders using Passive Inline Just-in-Time Decision Support

ImportanceElectronic health records (EHRs) allow teams of clinicians to simultaneously care for patients but an unintended consequence could result in duplicate ordering of tests and medications.\n\nObjectiveWe asked if a simple visual aid would reduce duplicate ordering of tests and medications for busy teams of clinicians in our emergency department by placing a red highlight around the checkbox of a computer-based order if previously ordered.\n\nDesignWe performed an interrupted time series to analyze all patient visits 1 year before and 1 year after the intervention. Significance testing was performed using a negative binomial regression with Newey-West standard errors, correcting for patient level variables and environmental variables that might be associated with duplicate orders.\n\nSettingThe emergency department of an academic hospital in Boston, MA with 55,000 visits annually.\n\nParticipants184,722 consecutive emergency department patients.\n\nExposureIf an order had previously been placed during that ED visit, we cue the user by showing a red highlight around the checkbox of that order.\n\nMain OutcomeNumber of unintentional duplicate orders.\n\nResultsAfter deployment of the non-interrupting nudge, the rate of unintentional duplicates for laboratory orders decreased 49% (incidence rate ratio 0.51, 95% CI 0.45-0.59) and for radiology orders decreased with an incidence rate ratio of 0.60 (0.44-0.82). There was no change in unintentional medication duplicate orders. We estimated that the nudge eliminated 17,936 clicks in our EHR.\n\nConclusions and RelevancePassive visual queues that provide just-in-time decision support are effective, not disruptive of workflow, and may decrease alert fatigue in busy clinical environments.\n\nKey PointsO_ST_ABSQuestionC_ST_ABSCan a simple visual aid reduce duplicate ordering in an electronic health record?\n\nFindingsIn this interrupted time series, the rate of unintentional duplicates for laboratory orders decreased 49% and for radiology orders decreased 40%. There was no change in unintentional medication duplicate orders. We estimated that the nudge eliminated 17,936 clicks in our EHR.\n\nMeaningQuality improvement often relies on changing clinician behavior. We believe guiding clinicians to a right action is better than telling the clinician they have already made an error. Our approach will help reduce alert fatigue and lessen clinician complaints about EHRs.

bioinformatics↗

bioRxiv2019

Role of human induced pluripotent stem cell-derived spinal cord astrocytes in the functional maturation of motor neurons in a multielectrode array system

The ability to generate human induced pluripotent stem cell (hiPSC)-derived neural cells displaying region-specific phenotypes is of particular interest for modeling central nervous system (CNS) biology in vitro. We describe a unique method by which spinal cord hiPSC-derived astrocytes (hiPSC-A) are cultured with spinal cord hiPSC-derived motor neurons (hiPSC-MN) in a multielectrode array (MEA) system to record electrophysiological activity over time. We show that hiPSC-A enhance hiPSC-MN electrophysiological maturation in a time-dependent fashion. The sequence of plating, density, and age in which hiPSC-As are co-cultured with MN, but not their respective hiPSC line origin, are factors that influence neuronal electrophysiology. When compared to co-culture with mouse primary spinal cord astrocytes, we observe an earlier and more robust electrophysiological maturation in the fully human cultures, suggesting that the human origin is relevant to the recapitulation of astrocyte/motor neuron cross-talk. Finally, we test pharmacological compounds on our MEA platform and observe changes in electrophysiological activity which confirm hiPSC-MN maturation. These findings are supported by immunocytochemistry and real time PCR studies in parallel cultures demonstrating human astrocyte mediated changes in the structural maturation and protein expression profiles of the neurons. Interestingly, this relationship is reciprocal and co-culture with neurons influences astrocyte maturation as well. Taken together these data indicate that in a human in vitro spinal cord culture system, astrocytes alter hiPSC-MN maturation in a time-dependent and species specific manner and suggest a closer approximation of in vivo conditions.\n\nMain PointsO_LIWe developed a method for the co-culture of human iPSC-A/MN for multielectrode array recordings.\nC_LIO_LIThe morphological, molecular, pharmacological, and electrophysiological characterization of the co-cultures suggests bidirectional maturation.\nC_LI

neuroscience↗

bioRxiv2019

Acute decrease in plasma membrane tension induces macropinocytosis via PLD2 activation

Internalization of macromolecules and membrane into cells through endocytosis is critical for cellular growth, signaling, and membrane tension homeostasis. Although endocytosis is responsive to both biochemical and physical stimuli, how physical cues modulate endocytic pathways is less understood. In contrary to the accumulating discoveries on effects of increased membrane tension on endocytosis, little is known about how a drop of tension impacts membrane trafficking. Here we reveal that acute reduction of plasma membrane tension results in phosphatidic acid, F-actin and dynamin 2-enriched dorsal membrane ruffling and subsequent macropinocytosis in myoblast. The membrane flaccidity-induced local phosphatidic acid production depends on phospholipase D2 (PLD2) that is activated via lipid raft disruption. Furthermore, the \"membrane flaccidity-PLD2-macropinocytosis\" pathway is dominant in myotube, reflecting a potential mechanism of membrane tension homeostasis upon intensive muscle stretching and relaxation. Together, we identify a new mechanotransduction pathway which converts acute tension drop into PA production and subsequently initiates macropinocytosis via actin and dynamin activities.\n\nSummaryWe reveal a mechanical induction of macropinocytosis that is elicited by acute decrease of plasma membrane tension, followed by lipid raft destabilization, PLD2 activation and PA production.

cell biology↗

bioRxiv2018

Evidence for absence of bilateral transfer of olfactory learned information in Apis dorsata and Apis mellifera

Capacity and condition under which lateral transfer of olfactory memory is possible in insects are still debated. Here we present evidence consistent with lack of ability to transfer olfactory associative memory in two species of honeybees, Apis mellifera and Apis dorsata in a PER associative conditioning paradigm where the untrained antenna is blocked by an insulating coat. We show that the olfactory system on each side of the bee can learn and retrieve independently and the retrieval using the antenna on the side contralateral to the trained one is not affected by the training. Recreating the paradigm in which the memory on the contralateral side has been reported at three hours after training we see that the memory is available on the contralateral side immediately after training and moreover, training with trained side antenna coated with insulator does not prevent learning, pointing to a possible insufficiency of block of odor stimuli in this paradigm. Bee does not learn the odor stimuli applied to one side alone as a stimulus different from odor presented to both sides. Moreover the behaviour of the bee as a whole can be predicted if the sides are assumed to learn and store independently and the organism as a whole is able to retrieve the memory if either of the sides have learned.\n\nSummary StatementThe two halves of honeybee brain store and retrieve olfactory associative memories independently.

animal behavior and cognition↗