Biology subjects

Davis, C. M.

Publications and source records attributed to Davis, C. M..

At least 19 recordsLinked to original sources

bioRxiv2026

msaGUI: Multispectral Analysis Graphical User Interface for Ratiometric Analysis and Background Correction

Chemical imaging is a powerful branch of modern microscopy encumbered by a lack of flexible, high-throughput analysis tools. Bespoke analytical pipelines typically perform ratiometric analysis on two layers in a multispectral image to describe the relative composition of molecules in a sample. This strategy has been implemented across fields, spanning histopathology, cell biology, environmental science, and materials science. The commercialization of chemical imaging microscopes has facilitated the collection of large multispectral datasets, necessitating accessible ways to process them. This paper describes Multispectral Analysis Graphical User Interface (msaGUI), a desktop graphical user interface to analyze individual and batch datasets of multispectral images. Data is loaded as CSV, TSV, or TIFFs and processed through a user-defined sequence of modular image operations that can be flexibly combined, e.g. to reduce spectral crosstalk or background noise. After analysis, data is visualized as exportable images, histograms, and statistics. To yield publication-quality figures, outputted images are fully customizable. Written in Python with open-source libraries, the msaGUI program is packaged into an executable for Windows and Mac for a fully no-code application. Other operating systems are supported via the Python source code. In summary, msaGUI provides a rapid and user-friendly solution for analyzing and visualizing multispectral data.

biophysics↗

bioRxiv2026

Expanding the methionine toolkit: L-cyanohomoalanine as a multifunctional analog

Non-canonical amino acids (ncAAs) are valuable tools in chemical biology and biochemistry for labeling, probing, and tracking biomolecules. ncAAs that can be recombinantly incorporated using native E. coli machinery are particularly useful because they allow for global protein incorporation and avoid complex genetic code expansion. Here, we demonstrate successful incorporation of a methionine analog, L-cyanohomoalanine (Cha), by the methionyl-tRNA synthetase of E. coli into mutant superfolder GFP (sfGFP) expressed in methionine auxotroph bacterial cultures. We compare to methionine auxotroph bacterial cultures supplemented with L-methionine (Met) or L-azidohomoalanine (Aha). In control prototrophic E. coli, bacterial growth rates are inhibited with high concentrations of Aha but not Cha. However, less sfGFP is produced in auxotrophic cells supplemented with Cha compared to Aha and Met. Thus, while Cha is non-toxic to E. coli it is incorporated less efficiently into proteins than Aha or Met. Mass spectrometry confirmed that N-terminal Cha, Aha, and Met are cleaved, as expected for the sfGFP mutants. Other sites of Cha and Aha incorporation were confirmed by mass spectrometry, with labeling efficiency varying by position. Thermal melts of purified sfGFPs demonstrate that Cha and Aha labeling does not significantly perturb the protein stability. In the future, Cha may be useful for proteome labeling by wild-type methionyl-tRNA synthetase and could be implemented in metabolic pulse-labeling of newly synthesized proteins with other methionine analogs. Additionally, the nitrile moiety of Cha may be used to perform reactions orthogonal to azide/alkyne click chemistry or could serve as a vibrational reporter of the environment.

biochemistry↗

bioRxiv2026

Label-Free AI-Classification of Subcellular Organelles Based on Optical Photothermal Infrared Images

Cells maintain homeostasis by dynamically reorganizing their organelles to tune metabolism in response to stress. Fluorescence microscopy maps organelle locations with subcellular resolution but provides limited information on their chemical composition. Infrared (IR) imaging offers a label-free alternative for probing intrinsic molecular vibrations that report on lipids, carbohydrates, and nucleic acids. However, its broader application to subcellular biology has been limited by spatial resolution and hyperspectral data complexity. Here, we combine submicron optical photothermal IR imaging with machine learning to classify subcellular structures in fixed U-2 OS cells. Using fluorescent-labeled organelles as ground truth, we trained and evaluated random forest (RF) classifiers and U-Net convolutional neural networks to identify organelles from IR spectra. The RF model converged rapidly, requiring fewer than 75 spectra per class per cell and fewer than 25 cells, indicating that models trained on small cellular regions can be extended to classify whole-cell images. The resulting classifiers accurately identified multiple organelles, including the endoplasmic reticulum, Golgi apparatus, mitochondria, nucleus, nucleolus, and stress granules. In contrast, classification was unsuccessful for nuclear speckles, actin, and microtubules, suggesting that some structures lack sufficiently distinct IR signatures under these conditions. Classifiers trained in U-2 OS cells generalized to HEK 293 cells, consistent with conserved organelle biochemical composition across cell types. However, the classifiers failed under cellular stress, indicating sensitivity to stress-induced changes in organelle state. Together, these results establish a scalable, label-free strategy for high-resolution mapping of organelle biochemical composition and provide a foundation for subcellular biomarker discovery and disease-state diagnostics.

biophysics↗

bioRxiv2026

Chemical interactions in polyethylene glycol-induced condensates lead to an anomalous FRET response from a flexible linker-fluorescent protein crowding sensor

The cellular cytosol is a crowded environment. Biomolecular Forster resonance energy transfer (FRET) sensors have been developed to measure crowding in cytosol mimics comprised of synthetic polymers such as polyethylene glycol (PEG) and Ficoll that impart an excluded volume effect. In the current study, we explore the unsolicited role of PEG in driving the phase separation of a protein crowding sensor, AcGFP1/mCherry-FRET crowding helix 2 (CrH2), into fluorescent puncta. In contrast, a DNA-based crowding sensor (CrD), with an Alexa488/Cy5 FRET pair, does not form puncta under the same crowding conditions. Using fluorescence recovery after photobleaching imaging, we uncover the liquid-like physical properties of the PEG-induced puncta. Two-color fluorescence microscopy imaging reveals crowder-induced inhomogeneity, concentration variations, and partition coefficient across the dilute and dense phases of the liquid puncta, which remain largely underexplored in bulk fluorometry measurements. Thus, the average crowding sensor response may originate from an aqueous biphasic system, reporting an erroneous average response instead of distinct levels of crowdedness. A comparison of excluded volume effects conferred by Ficoll and PEGs of various molecular weight ranges shows the influence of size, concentration, excluded volume, and chemical composition on the CrH2 sensor response. We demonstrate that PEGs enable phase separation and alter sensor response through a mechanism that may be driven by polymer interactions with the flexible hinge region of CrH2. Overall, we determine the biophysical mechanisms underlying PEG-induced condensation of CrH2 and demonstrate a CrD sensor as an alternative that does not undergo phase separation.

biophysics↗

bioRxiv2025

Persistent Cognitive Impairment and Bone Health Following Helium (4He) Ion Exposure: Implications for Space Travel

The current study investigated the long-term neurobehavioral and physiological effects of low-dose helium (4He; 250 MeV/n) ion exposure, a significant component of galactic cosmic radiation (GCR), on male Long Evans rats. Groups of rats were trained on the rodent psychomotor vigilance test (rPVT) and irradiated at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Following exposure, they were tested in the rPVT from 30 - 180 days, and assessed for social recognition memory at 30, 90, and 180 days. At each time point, blood and bone samples were collected for subsequent analysis. We found that acute exposure to 4He ions (25 cGy) significantly impaired sustained attention, resulting in increased lapses in attention, increased reaction time measures, and decreased correct responses. However, exposure to 5 cGy 4He ions only increased some reaction time measures in the rPVT. Both groups displayed impaired social recognition memory. When deficits were found, they persisted for 180 days post-exposure, showing no signs of recovery. Notably, impairments in sustained attention appeared to worsen over time. While these low exposure doses of 4He did not significantly alter overall bone mechanical properties, specific individual parameters of bone strength were affected, and age-related changes likely played a role in observed skeletal integrity changes. Furthermore, we identified significant correlations between circulating cytokines (TNF-, IL-1{beta}), undercarboxylated osteocalcin (ucOC) levels, and bone biomechanical properties with behavioral performances. These findings suggest the potential for these blood- and bone-based targets to serve as diagnostic biomarkers for radiation-induced neurobehavioral effects, opening avenues for future countermeasure development. The sustained and progressive nature of the neurobehavioral deficits observed underscores the critical need for effective countermeasures to protect astronaut health and performance during exploration-class missions.

animal behavior and cognition↗

bioRxiv2025

Optical photothermal infrared imaging of fatty acid metabolism in the ER of living cells

Lipotoxicity is an accumulation of lipids that leads to cell death and metabolic disease. Saturated fatty acids are more likely to cause lipotoxicity, however, the mechanism remains unclear due to challenges visualizing reactions in live cells. Here, we use optical photothermal infrared (OPTIR) microspectroscopy to investigate palmitic acid (PA) metabolism in hepatocytes with sub-micron spatial resolution. Upon PA feeding, we discover a time-dependent ester carbonyl stretch localized to the ER and lipid droplet-ER contact sites of lipid droplets with abnormal morphology. This stretch is assigned to diacylglycerol intermediates in the glycerol-3-phosphate pathway. C-D stretches of deuterated PA provide complementary molecular details, supporting a model whereby PA acyl chain packing in the ER reduces enzyme diffusion slowing PA metabolism. Our results provide a deeper understanding of how phase changes induced by high melting temperature fatty acids and their metabolites change ER chemistry as well as provides a tool for detecting chemical and environmental changes associated with lipotoxicity in live cells. TeaserSub-micron IR imaging of palmitic acid metabolism in live cells reveals diacylglycerol buildup and gel phase changes in the ER.

biophysics↗

bioRxiv2025

Conformations and sequence determinants in the lipid binding of an adhesive peptide derived from Vibrio cholerae biofilm

Surface adhesion is critical to the survival of pathogenic bacteria both in natural niches and during infections, often via forming matrix-embedded communities called biofilms. We previously identified a 57-amino acid peptide (Bap1-57aa) as a key contributor to biofilm adhesion of the pandemic pathogen Vibrio cholerae to various surfaces including lipid membranes. Here, we combine biophysical, computational, and genetic approaches to elucidate the molecular mechanism. A central aromatic-rich motif anchors the peptide to lipid bilayers while peripheral pseudo repeats enhance binding through avidity. Surprisingly, the core motif undergoes a lipid-induced conformational transition into a {beta}-hairpin, enabling robust membrane insertion. Moreover, the biofilm-derived peptide, conserved in several other Vibrio species, can adhere to model host surfaces and is sensitive to membrane curvature. Our results provide molecular insight into biofilm adhesion and may lead to new strategies for targeted biofilm removal and the design of bioinspired underwater adhesives. TeaserA short peptide from Vibrio cholerae binds lipids using a unique {beta}-hairpin motif and contributes to host colonization.

microbiology↗

bioRxiv2024

Weak, specific chemical interactions dictate barnase stability in diverse cellular environments

It is well-established that in vitro measurements do not reflect protein behaviors in-cell, where macromolecular crowding and chemical interactions modulate protein stability and kinetics. Recent work suggests that peptides and small proteins experience the cellular environment differently from larger proteins, as their small sizes leave them primarily susceptible to chemical interactions. Here, we investigate this principle in diverse cellular environments, different intracellular compartments and host organisms. Our small protein folding model is barnase, a bacterial ribonuclease that has been extensively characterized in vitro. Using fast relaxation imaging, we find that FRET-labeled barnase is stabilized in the cytoplasm and destabilized in the nucleus of U2-OS cells. These trends could not be reproduced in vitro by Ficoll and M-PERTM, which mimic macromolecular crowding and non-specific chemical interactions, respectively. Instead, in-cell trends were best replicated by cytoplasmic and nuclear lysates, indicating that weak specific interactions with proteins in either compartment are responsible for the in-cell observations. Interestingly, in the cytoplasm barnases unfolded state is unstable and prone to aggregation, while in the nucleus a stable unfolded state exists prior to aggregation. In the more biologically relevant environment of bacterial cells, barnase folding resembled that in the nucleus, but with no aggregation at higher temperatures. These findings show that protein interactions are evolved for their native environment, which highlights the importance of studying and designing proteins in situ.

biophysics↗

bioRxiv2024

Optical photothermal infrared imaging using metabolic probes in biological systems

Infrared spectroscopy is a powerful tool for identifying biomolecules. In biological systems, infrared spectra provide information on structure, reaction mechanisms, and conformational change of biomolecules. However, the promise of applying infrared imaging to biological systems has been hampered by low spatial resolution and the overwhelming water background arising from the aqueous nature of in cell and in vivo work. Recently, optical photothermal infrared microscopy (OPTIR) has overcome these barriers and achieved both spatially and spectrally resolved images of live cells and organisms. Here, we determine the most effective modes of collection on a commercial OPTIR microscope for work in biological samples. We examine three cell lines (Huh-7, differentiated 3T3-L1, and U2OS) and three organisms (E. coli, tardigrades, and zebrafish). Our results suggest that the information provided by multifrequency imaging is comparable to hyperspectral imaging while reducing imaging times twenty-fold. We also explore the utility of IR active probes for OPTIR using global and site-specific noncanonical azide containing amino acid probes of proteins. We find that photoreactive IR probes are not compatible with OPTIR. We demonstrate live imaging of cells in buffers with water. 13C glucose metabolism monitored in live fat cells and E. coli highlights that the same probe may be used in different pathways. Further we demonstrate that some drugs (e.g. neratinib) have IR active moieties that can be imaged by OPTIR. Our findings illustrate the versatility of OPTIR, and together, provide a direction for future dynamic imaging of living cells and organisms.

biophysics↗

bioRxiv2024

Disease and ectoparasite management improve nestling golden eagle health and survival: An effective mitigation strategy

Changes in the distribution and behavior of pathogens and parasites associated with climate change are creating emerging threats for wildlife. These threats have created an urgent need for conservation strategies to manage wildlife. Conservation strategies could provide reliable and cost-effective compensatory mitigation options for protected species affected by renewable energy production, such as golden eagles (Aquila chrysaetos). We used nest camera data to assess survival and cause of death for golden eagle nestlings in southern Idaho, USA. Together, poultry bugs (Haematosiphon inodorus), a blood-sucking ectoparasite that lives in golden eagle nests, and trichomonosis, a fatal disease that is transmitted through the consumption of rock pigeons (Columba livia) caused [~] 27% of nestlings to die per year. From 2022--2023, we treated trichomonosis-infected nestlings with an anti-protozoan drug and developed a protocol for reducing poultry bug densities in eagle nests, then we projected the effects of disease and parasite treatments on population growth using simulation models. We collected pre-treatment information on nestling health and survival, and then, after young fledged, we applied 1 of 3 experimental parasite treatments to eagle nests: permethrin and diatomaceous earth, diatomaceous earth only, or water - a control, and measured effects on eagle health and survival the following year. Ten eagle nestlings with trichomonosis, that otherwise would have died, were successfully treated and lived to fledge from the nest. The permethrin and diatomaceous earth treatment significantly reduced poultry bug densities in eagle nests in the subsequent breeding season and created measurable improvements to nestling health and survival. Nestlings had significantly higher hematocrit, female nestlings had higher mass, and, on average, more nestlings (0.70) successfully survived to fledge compared with control- and diatomaceous earth-treated nests. Further, treatment of disease and parasites was projected to increase population growth rates by 4% and 8%, respectively. In total, we estimate saving 17.5 nestlings, which equates to 10.2 adult eagles, through disease and parasite treatments in two years. In areas with dense concentrations of poultry bugs or where eagles consume rock pigeons, disease and parasite treatments could be an effective compensatory mitigation option or management tool with population-level impacts on eagle populations.

ecology↗

bioRxiv2024

Sleep deprivation and the rodent psychomotor vigilance test (rPVT): Assessing lapses in attention, the response stimulus interval effect, and time on task in rats using food reinforcement

Study objectiveSleep deprivation (SD) impairs sustained attention when assessed with the psychomotor vigilance test (PVT). Food restriction attenuates the effects of SD on sustained attention in rats, possibly limiting translation of rodent tests. Our goal was to determine if an rPVT requiring high baseline performance was sensitive to the effects of SD when using food restriction and reinforcement. MethodsrPVT-trained rats experienced SD and were tested the following day. ResultsSD significantly increased lapses, and this effect was specific to shorter response-stimulus intervals. Decreased percent correct responses and increased slow reaction times were also found following SD. ConclusionThe rPVT is sensitive to the performance impairing effects of SD in food restricted rats, a common methodology used to train and maintain performance on operant tests.

animal behavior and cognition↗

bioRxiv2023

The Natural Products Discovery Center: Release of the First 8490 Sequenced Strains for Exploring Actinobacteria Biosynthetic Diversity

Actinobacteria, the bacterial phylum most renowned for natural product discovery, has been established as a valuable source for drug discovery and biotechnology but is underrepresented within accessible genome and strain collections. Herein, we introduce the Natural Products Discovery Center (NPDC), featuring 122,449 strains assembled over eight decades, the genomes of the first 8490 NPDC strains (7142 Actinobacteria), and the online NPDC Portal making both strains and genomes publicly available. A comparative survey of RefSeq and NPDC Actinobacteria highlights the taxonomic and biosynthetic diversity within the NPDC collection, including three new genera, hundreds of new species, and [~]7000 new gene cluster families. Selected examples demonstrate how the NPDC Portals strain metadata, genomes, and biosynthetic gene clusters can be leveraged using genome mining approaches. Our findings underscore the ongoing significance of Actinobacteria in natural product discovery, and the NPDC serves as an unparalleled resource for both Actinobacteria strains and genomes.

microbiology↗

bioRxiv2023

Oleic acid differentially affects de novo lipogenesis in adipocytes and hepatocytes

Lipogenesis is a vital but often dysregulated metabolic pathway. We report super-resolution multiplexed vibrational imaging of lipogenesis rates and pathways using isotopically labelled oleic acid and glucose as probes in live adipocytes and hepatocytes. These findings suggest oleic acid inhibits de novo lipogenesis (DNL), but not total lipogenesis, in hepatocytes. No significant effect is seen in adipocytes. These differential effects may be due to alternate regulation of DNL between cell types and could help explain the complicated role oleic acid plays in metabolism.

biophysics↗

bioRxiv2023

Site-Specific Crosslinking Reveals Phosphofructokinase-L Inhibition Drives Self-Assembly and Attenuation of Protein Interactions

Phosphofructokinase is the central enzyme in glycolysis and constitutes a highly regulated step. The liver isoform (PFKL) compartmentalizes during activation and inhibition in vitro and in vivo respectively. Compartmentalized PFKL is hypothesized to modulate metabolic flux consistent with its central role as the rate limiting step in glycolysis. PFKL tetramers self-assemble at two interfaces in the monomer (interface 1 and 2), yet how these interfaces contribute to PFKL compartmentalization and drive protein interactions remains unclear. Here, we used site-specific incorporation of noncanonical photocrosslinking amino acids to identify PFKL interactors at interface 1, 2, and the active site. Tandem mass tag-based quantitative interactomics reveals interface 2 as a hotspot for PFKL interactions, particularly with cytoskeletal, glycolytic, and carbohydrate derivative metabolic proteins. Furthermore, PFKL compartmentalization into puncta was observed in human cells using citrate inhibition. Puncta formation attenuated crosslinked protein-protein interactions with the cytoskeleton at interface 2. This result suggests that PFKL compartmentalization sequesters interface 2, but not interface 1, and may modulate associated protein assemblies with the cytoskeleton.

biochemistry↗

bioRxiv2021

Δ9-tetrahydrocannabinol (THC) vapor exposure produces conditioned rewarding effects in male and female rats

BackgroundThe use of place conditioning procedures and drug vapor exposure models can increase our understanding of the rewarding and aversive effects of vaped cannabis products. Currently there are limited data on the conditioned rewarding effects of vaporized {Delta}9-tetrahydrocannabinol (THC), the primary psychoactive constituent of cannabis in rats, and no studies to date examining sex differences. MethodsMale and female Sprague-Dawley rats (N=96; 12 per sex/group) underwent place conditioning sessions immediately after exposure to THC or vehicle (propylene glycol, PG) vapor. Locomotor activity was measured by beam breaks during conditioning sessions. THC vapor-conditioned rats received one of three THC vapor exposure amounts (low: 5 puffs of 100 mg/ml THC, medium: 5 puffs of 200 mg/ml THC, or high: 10 puffs of 200 mg/ml THC) and matched vehicle vapor (PG) exposure on alternate days for 16 daily sessions. A no THC control group of vehicle-conditioned rats received only PG vapor exposure each day. After the 8th and 16th conditioning sessions, untreated rats were tested for conditioned place preference (CPP) or avoidance (CPA). Next, extinction tests and a THC vapor-primed reinstatement test were conducted. ResultsTHC vapor produced CPP and locomotor effects in an exposure dependent manner, and some sex differences were observed. Low THC vapor exposure did not produce CPP in males or females. Medium THC vapor exposure produced CPP in males, but not females. High THC vapor exposure produced CPP in both males and females. Medium and high THC vapor exposure amounts produced hyperactivity in female rats, but not male rats. CPP was more resistant to extinction in females than males. THC vapor re-exposure (i.e., drug-prime) after extinction did not result in reinstatement of CPP for either sex. ConclusionThis study demonstrates conditioned rewarding effects of THC vapor in both male and female rats and provides evidence for sex differences in amounts of THC vapor that produce CPP and in time to extinction. CPA was not observed at any of the THC vapor exposure amounts tested. These data provide a foundation for future exploration of the conditioned effects of cannabis constituents and extracts using vapor exposure models.

animal behavior and cognition↗

bioRxiv2021

Photochemical pre-bleaching of formalin-fixed archival prostate tissues significantly reduces autofluorescence to facilitate multiplex immunofluorescence staining

The characterization of tissues using multiple different primary antibodies detected by secondary antibodies, each possessing a different colored fluorophore (multiplex immunofluorescence), is a powerful technique but often impaired by endogenous autofluorescence present in the specimen. Our current research involves the use of multiplex immunofluorescence to identify specific cell phenotypes within the tumor microenvironment in archival formalin-fixed paraffin-embedded human prostate cancer tissue specimens. These specimens frequently possess high levels of autofluorescence, in part due to the biological age of the tissues and long storage times. This autofluorescence interferes with and, in the worst cases, completely obscures the desired immunofluorescent signals, thus impeding analyses by decreasing signal-to-noise. Here, we demonstrate that a recently published protocol for photochemical bleaching significantly decreases autofluorescence (80% average decrease of the brightest autofluorescent signals), across the visible spectrum, in fixed, archival prostate tissue specimens from aged men, that have been sectioned onto glass slides and stored for several months. Importantly, the method is compatible with subsequent immunofluorescence staining and yields markedly improved signal-to-noise. Inclusion of this method should facilitate studies employing multiplex immunofluorescence in sections cut from archival fixed human prostate tissues.

pathology↗

bioRxiv2020

A Draft Reference Genome for Hirudo verbana, the Medicinal Leech

The medicinal leech, Hirudo verbana, is a powerful model organism for investigating fundamental neurobehavioral processes. The well-documented arrangement and properties of H. verbanas nervous system allows changes at the level of specific neurons or synapses to be linked to physiological and behavioral phenomena. Juxtaposed to the extensive knowledge of H. verbanas nervous system is a limited, but recently expanding, portfolio of molecular and multi-omics tools. Together, the advancement of genetic databases for H. verbana will complement existing pharmacological and electrophysiological data by affording targeted manipulation and analysis of gene expression in neural pathways of interest. Here, we present the first draft genome assembly for H. verbana, which is approximately 250 Mbp in size and consists of 61,282 contigs. Whole genome sequencing was conducted using an Illumina sequencing platform followed by genome assembly with CLC-Bio Genomics Workbench and subsequent functional annotation. Ultimately, the diversity of organisms for which we have genomic information should parallel the availability of next generation sequencing technologies to widen the comparative approach to understand the involvement and discovery of genes in evolutionarily conserved processes. Results of this work hope to facilitate comparative studies with H. verbana and provide the foundation for future, more complete, genome assemblies of the leech.

genomics↗

bioRxiv2020

Antinociceptive, hypothermic, and appetitive effects of vaped and injected Δ9-tetrahydrocannabinol (THC) in rats: exposure and dose-effect comparisons by strain and sex

Advances in drug vapor exposure systems utilizing e-cigarette technology have enabled evaluation of {Delta}-9-tetrahydrocannabinol (THC) vapor effects in laboratory animals. The purpose of this study was to 1) establish a range of parameters of THC vapor exposure in rats sufficient to produce a behavioral dose-effect curve in a battery of tasks sensitive to THC; 2) to investigate sex differences in the effects of THC vapor exposure and THC injection (intraperitoneal, IP) on these behaviors in two strains of outbred rats. Male and female Wistar and Sprague Dawley rats (N=22, 5-6/group) received THC via IP injection (1-20 mg/kg) and passive exposure to THC vapor (200 mg/ml; 5 conditions) in a within subject design. The effects of vaped and injected THC were determined using the tail-withdrawal assay for nociception, rectal measurements of body temperature, and progressive-ratio responding for food pellets. Plasma THC concentrations were assessed after 10 mg/kg IP THC or THC vapor. THC produced dose and exposure-dependent antinociception and hypothermia. THC vapor produced inverted U-shaped effects in motivation to obtain food, while IP THC reduced PR breakpoints. Plasma THC concentrations were higher after 10 mg/kg IP THC (152 ng/mL) compared to the highest vapor exposure condition tested (38 ng/mL). THC vapor exposure produces reliable, dose-orderly effects on nociception, body temperature, and food-maintained behavior that is comparable to effects observed after IP THC. There are considerable differences between the time course of behavioral outcomes produced by these two different routes of administration.

animal behavior and cognition↗