Journal of Chemical Ecology

O_LIVolatile organic compounds (VOCs) mediate plant-plant signalling and may contribute to phenotypic differentiation among populations. However, the extent to which VOC-mediated signalling varies among locally adapted populations, and how VOC traits relate to major fitness-related traits, remain poorly understood. C_LIO_LIWe conducted a greenhouse experiment using two genetically and phenologically divergent Iberian populations of Arabidopsis thaliana. Plants were exposed to herbivory by Spodoptera exigua, after which we quantified herbivore-induced VOC emissions, VOC-mediated signalling effects on neighbouring conspecifics, and relationships between VOC traits, flowering time, and seed germination. C_LIO_LIHerbivory altered VOC composition, but overall VOC profiles remained broadly similar between populations despite strong divergence in life-history strategies, constitutive resistance to herbivory, and genetic structure. In contrast, correlations between VOC traits and fitness-related traits differed between populations and herbivory treatments. Nevertheless, receiver plants from both populations exhibited reduced herbivore damage after exposure to herbivore-induced emitters, indicating conserved VOC-mediated signalling. C_LIO_LIOur results suggest that herbivore-induced volatile signalling may represent a relatively conserved component of plant defence across locally adapted populations. In contrast, relationships between VOC traits and life-history variation may reflect population-specific integration of defence and fitness-related traits. C_LI

Due to climate change, extreme weather events such as droughts are becoming more frequent and intense. This has a profound impact on plant performance and ecological interactions, including those involving herbivorous insects. The combined impact of drought stress and insect herbivory on plant metabolism has rarely been studied, particularly in woody plants. In this study, we investigated the influence of varying degrees of drought, both alone and in combination with herbivory by the leaf beetle Chrysomela tremulae, on the morphological and chemical characteristics of black poplar (Populus nigra) trees using a full factorial experimental design. We quantified morphological traits, volatile organic compound (VOC) emissions, phytohormone and amino acid concentrations, and phenolic profiles. Drought conditions increased the concentrations of salicylic acid (SA) and abscisic acid (ABA), while feeding induced ABA and SA. Amino acid profiles shifted significantly under drought conditions, particularly in beetle-infested plants. In contrast, salicinoids, which are the most important phenolic defense compounds in poplars, remained relatively stable. We also observed significant compound-specific effects on both constitutive and herbivore-induced VOC emissions. Our results demonstrate that drought and insect herbivory exert a joint influence on the chemical responses of P. nigra across multiple metabolic pathways. These findings highlight how the interaction between abiotic and biotic stresses can influence the defense chemistry of trees, which will consequently affect ecological interactions in forest ecosystems in the face of climate change.

O_LIEuropean beech (Fagus sylvatica L.) is a widely distributed, ecologically and economically important deciduous tree species in European forests, but is increasingly threatened by drought stress. Volatile organic compounds (VOCs) are ubiquitous plant metabolites that may serve as non-invasive biomarkers of drought stress, yet they have rarely been studied in European beech. C_LIO_LIIn this study, we examined VOC responses of European beech to experimental drought across diverse genetic backgrounds in a common garden. The 72 four-year-old beech saplings represented three genetic clusters, seven provenances (geographic seed sources), and 12 maternal seed families. Half of the saplings were assigned to the drought treatment and received no water for 14 days, while the remaining saplings served as controls and were watered as required. VOC profiles, quantified as peak heights of mass spectral features, were measured for all individuals during pre-drought, drought, and rewatering periods. C_LIO_LIWe found that pre-drought VOC profiles, in particular monoterpenes, varied significantly among genetic backgrounds. Experimental drought significantly altered VOC profiles, characterized by increased green leaf volatiles and decreased monoterpenes, oxidized terpenoid derivatives, and other fatty acid derivatives. Reductions in monoterpenes persisted after rewatering, indicating a drought legacy effect. Drought responses were largely conserved across genetic backgrounds, with significant seed family-specific responses detected for only three VOC features. C_LIO_LIOur findings suggest that VOC profiles are genetically structured yet highly plastic under drought and highlight their potential as non-invasive biomarkers for monitoring drought stress in European beech under climate change. C_LI

The Eurasian spruce bark beetle Ips typographus, a major forest pest on Norway spruce (Picea abies), forms intimate associations with several types of microbial symbionts. While previous research has focused primarily on filamentous fungi, yeasts have remained largely unexplored. Here, we show that yeasts associated with I. typographus may contribute to host tree colonization by providing defensive benefits. Dominant yeasts (Yamadazyma, Kuraishia, Nakazawaea, and Wickerhamomyces), which are phylogenetically related to other insect-associated Saccharomycotina, significantly attract adult beetles. Moreover, several yeasts inhibit the growth of the pathogenic fungus Trichoderma harzianum in vitro, and beetle eggs benefit from the presence of Kuraishia capsulata by reduced fungal infection under semi-natural conditions. Strikingly, these effects are mediated by the yeasts' transformation of the tree's defensive stilbene glycosides into antimicrobial aglycones and phenolic acids that accumulate in beetle galleries. These findings reveal a previously unrecognized role of symbiotic yeasts in converting spruce defensive stilbene glycosides into antimicrobial aglycones and oxidative cleavage products that accumulate in beetle galleries, and might contribute to the survival of their bark beetle host.

Adult mosquitoes rely on plant-derived sugars for survival, reproduction, and flight, yet the plant taxa that mosquitoes encounter in nature and the odors that make those plants attractive remain poorly understood. Most studies of mosquito attraction to plant odors have focused on candidate plants selected a priori, rather than plants linked to field-collected mosquitoes. Here, we combined plant DNA barcoding, semi-field behavioral assays, and volatile profiling to identify field-associated plant resources relevant to Aedes aegypti. Plant DNA recovered from mosquitoes collected across three Florida counties revealed broad plant associations, including 90 genera spanning 37 families, with several taxa recurring across counties or appearing prominently within particular localities. Behavioral experiments in semi-field sticky-trap assays found that five field-associated plant taxa were significantly attractive relative to blank controls, indicating that taxa associated with mosquitoes in nature can also function as attractive cues under semi-field conditions. GC-MS analyses of headspace collections from 42 plant taxa detected 211 volatile compounds and revealed substantial variation in both total emission rate and odor composition among taxa. Although several compounds, including -pinene, limonene, 4-ethylacetophenone, 2-ethyl-1-hexanol, 4-ethylbenzaldehyde, and caryophyllene, were broadly distributed across plant groups, volatile profiles differed significantly among taxa and shared compounds often occurred at markedly different proportional abundances. The five behaviorally tested taxa likewise showed both overlap and divergence, sharing 17 compounds across all five taxa while differing in dominant constituents and total emissions. Together, these results show that Ae. aegypti interacts with a diverse set of plants in the field, and suggests nectar-seeking is shaped not simply by plant identity or total odor abundance, but by the composition and proportional structure of plant odors.

TULIP (TUbular LIPid binding) domain proteins (TDPs) are found in all living organisms including bacteria. They have various documented functions, some of which clearly related to their intra- or extracellular lipid transfer activities. Extracellular, BPI-related TDPs of insects (B-TDPs, also known as Takeout-related proteins), are often found in chemosensory organs, but little is known regarding their exact location or how they could contribute to olfaction or gustation. We have surveyed and updated the full set of Drosophila B-TDPs and found that roughly 50% are overexpressed in chemosensory organs. Focusing on three genes clustered on the third chromosome, we provide evidence that at least one of the encoded proteins is secreted in the lymph cavity housing the dendrites of olfactory neurons. Biochemical data give support for a putative function of B-TDPs as odorant transporters, but loss-of-function analyses also hint to a potential role as a barrier against plant-emitted terpenoids.

Pesticides remain indispensable for global food security, yet their use must be reconciled with the preservation of biodiversity. Despite advances in developing safer pesticides, their sublethal effects and synergistic potential with co-formulants in tank-mixtures, including inert spray adjuvants, often remain poorly understood in beneficial insects like bees. In this study, we assessed the effects of acute oral exposure to field-realistic doses of SilwetTM L-77 (an organosilicone adjuvant; 0.1-2.5%), acetamiprid (a cyano-substituted neonicotinoid; 6-150 ng/bee), and sulfoxaflor (a sulfoximine; 3-27 ng/bee) on gustatory responsiveness, associative olfactory learning, and short-term memory retention in honeybees (Apis mellifera L.). While we found no significant evidence of interaction effects at the exposure concentrations tested, the highest doses of SilwetTM L-77 and sulfoxaflor alone significantly reduced gustatory responsiveness. Furthermore, all three agrochemicals alone weakly affected associative learning without impacting memory retention. Although adjuvant-insecticide mixtures did not synergistically impair bee cognition, these adjuvants can impact sensory perception. Moving beyond mortality-based assessments and including sensory-cognitive thresholds is essential for a more holistic understanding of pollinator health.

Bisphenol S (BPS), a widely used substitute for bisphenol A, is increasingly detected in aquatic environments; however, its neurodevelopmental effects remain insufficiently understood. This study investigated whether developmental exposure to an environmentally relevant concentration of BPS disrupts social behaviour and underlying neurobiological pathways in zebrafish (Danio rerio). At 21 days post-fertilization, BPS-exposed larvae exhibited a significant reduction in social preference, indicating impaired conspecific interactions. Neurochemical analysis revealed a marked increase in serotonin (5-HT) levels, whereas lipid peroxidation (MDA) remained unchanged, suggesting the absence of overt oxidative damage. Gene expression profiling demonstrated a dysregulated antioxidant response, suppression of apoptotic signaling, and pronounced upregulation of serotonergic receptors and transporters. To resolve system-level mechanisms, protein-protein interaction (PPI) network analysis identified BDNF and CREB1 as dominant regulatory hubs, with the serotonergic synapse pathway as the most significantly enriched term. Molecular docking further demonstrated direct binding of BPS to multiple serotonergic targets, including HTR1A and TPH2, supporting receptor-level interference. Expanded network and pathway analyses revealed coordinated enrichment of monoamine GPCR, oxidative stress, and inflammatory pathways. These findings demonstrate that BPS induces serotonergic dysregulation and network-level reprogramming rather than significant oxidative damage, leading to behavioural impairment. This study provides a multi-scale mechanistic framework linking molecular perturbations to neurobehavioural outcomes, identifying serotonergic signaling and BDNF-CREB1 pathways as central targets of BPS neurotoxicity.

Herbicide resistance threatens effective weed control in modern agriculture, particularly in grass weeds such as Alopecurus myosuroides and Lolium multiflorum. Cinmethylin is a pre-emergence herbicide with a novel mode of action that inhibits plastidial fatty acid thioesterases (FATs), enzymes essential for fatty acid biosynthesis. Although no cases of field resistance to cinmethylin have been reported, its resistance risk has not been fully assessed. In this study, we biochemically characterized defined amino acid substitutions in FAT A and FAT B to evaluate their effects on cinmethylin inhibition profile. Some substitutions in FAT A reduced inhibition in vitro, with mutations at residue R171 causing the largest shifts in sensitivity. However, these highly resistant variants required multiple specific nucleotide polymorphisms and are therefore predicted to be unlikely to arise in weed populations. In FAT B, sensitivity shifts were generally moderate. Importantly, most substitutions that reduced cinmethylin sensitivity also impaired enzymatic activity, suggesting limited viability in planta. Overall, these results indicate that while theoretical target-site resistance mechanisms exist, the practical risk of rapid resistance evolution to cinmethylin is low, supporting its value for integrated grass weed management

Xylosandrus crassiusculus (Motschulsky), the granulate ambrosia beetle, was one of the first highly-destructive ambrosia beetles introduced into the southern U.S in the 1970s where it was found in South Carolina (Kovach 1986). The Redbay ambrosia beetle, Xyleborus glabratus Eichhoff, was first detected in the U.S. in South Georgia in 2002. This beetle and its associated fungi, the laurel wilt fungus Raffaelea laurelensis and others have caused substantial destruction to native redbay (Persea borbonia) in GA, SC, FL and elsewhere. This beetle-pathogen complex also poses a threat to commercial avocado production in the U.S., Central and South America as well as to valuable other Persea spp. and related plants (Laureacea) that are known hosts. As an addition here, 10 years of the spring appearances (Fig.1) of X. crassiusculus in North Florida is offered for future comparisons. A second unusual appearance is the finding and working with UV mulch and ethanol, as a surprising attraction of X. crassiusculus and other ambrosia beetles including X. glabratus. It was also found that the ambrosia beetles do not respond to yellow and green as expected by most. Also, adding burlap was found to be attractive (increases dead and dying appearing trees) as is silver metallic like UV mulch, while camouflage (camo) was found to work like yellow and green. These occurrences led to the invention and development of UV mulch with new traps to better monitor ambrosia beetles. New traps led to new uses for yellow, green and camo to monitor and decrease damage and losses from ambrosia beetles. The data are presented as evaluated and appear in the figures, discussion and a supplemental section. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/733798v1_fig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1006101org.highwire.dtl.DTLVardef@1e0a3d6org.highwire.dtl.DTLVardef@1244d1borg.highwire.dtl.DTLVardef@423cb7_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Relative timing of annual emergence of Xylosandrus crassiusculus in north Florida. Collected over 10 years using 5 Baker traps with a 10% ethanol/water solution. Data are from years as marked. Note: data from year 2003 was not collected. C_FIG

In many insect species, mating is coordinated through multimodal signaling, yet less obvious channels are often overlooked. In the burying beetle Nicrophorus vespilloides, chemical communication is well-documented, but the role of substrate-borne vibrational signals (stridulations) during courtship remains unknown. We investigated whether stridulation is essential for mating success through two sets of experiments. First, we found a positive correlation between the frequency of stridulations and both the number and duration of copulation events. Second, we employed a silencing experiment to test the necessity of these signals by silencing males, females, or both partners. We found no significant differences between silenced and control groups regarding the frequency or duration of physical contact and mounting events, suggesting that stridulation is not required for mate recognition or the initiation of courtship. However, the proportion of successful copulations relative to mounting events was significantly lower when females were silenced. These results suggest that while N. vespilloides relies on a redundant multimodal system that likely utilizes chemical cues to initiate mating, vibrational signals, particularly from the female, may play a critical role in facilitating successful copulation. This study provides the first evidence for the role of stridulation in the mating behavior of N. vespilloides and highlights the potential for female-mediated vibrational signaling in burying beetle courtship.

It was recently reported that Methylobacterium extorquens AM1 produces the citrate-hydroxamate siderophore N-deoxyschizokinen A, identified by LC-HRMS. Multiple properties were inconsistent with the assignment: the feature eluted far later than the other schizokinen derivatives (17 min versus 6-8 min), a reversed-phase shift larger than a single-hydroxyl difference in a molecule can explain, further its accurate mass deviated from the calculated one by 28 ppm, well outside the error on the co-analyzed standards and its diagnostic m/z 105 and 77 fragments suggest a molecule with an aromatic moiety. A replicate comparison of identical samples in plastic versus glass autosampler vials was decisive: the m/z 387 feature was reproducibly present with plastic vials and absent with glass. We therefore conclude that the reported detection of N-deoxyschizokinen A in M. extorquens AM1 is an artifact, and recommend glass-vial and solvent-blank controls, an explicit accurate-mass threshold, and narrow MS/MS isolation when assigning trace siderophore-like features from complex extracts.

Boavistamide A (1), a new alkyne-containing cyclic depsipeptide featuring the rare 3-amino-2-methyl-7-octynoic acid (AMOYA) moiety, was discovered along with two structurally related analogs, boavistamides B and C (2 and 3), from a filamentous marine cyanobacterium collected on Boa Vista Island, Cabo Verde. Their isolation was guided by antiplasmodial activity, GNPS MS/MS molecular networking, LC-MS profiling, and dereplication using the MarinLit database. The planar structures of boavistamides A-C (1-3) were elucidated through comprehensive HRMS and 1D/2D NMR analyses, with annotation support from AI-based tools SMART-NMR 2.1 and DeepSAT. The absolute configurations were established using Marfeys analysis and L-Phe-OMe coupling, complemented by NMR-based conformational studies. Boavistamides A and B exhibited moderate antiplasmodial activity with no mammalian cell cytotoxicity. Microscopic observations and metagenomic binning identified the producer strain as belonging to the genus Okeania (Microcoleaceae). These results expand the chemical diversity of AMOYA-containing cyanobacterial metabolites and highlight the utility of integrated metabolomics and AI-assisted workflows for natural product discovery from environmental samples. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/732064v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@24ce2borg.highwire.dtl.DTLVardef@5ba292org.highwire.dtl.DTLVardef@e1f6dorg.highwire.dtl.DTLVardef@1312d22_HPS_FORMAT_FIGEXP M_FIG C_FIG

Antimicrobial resistance represents a continuing threat to clinical infection management, with methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Escherichia coli identified by the World Health Organization as priority pathogens. This study evaluated the antimicrobial activity, synergistic potential, and chemical composition of six plant-derived preparations (three ethanolic extracts: nettle, thyme, rosemary; and three essential oils: lavender, lemongrass, doTERRA Peace blend) against MRSA, methicillin-sensitive S. aureus (MSSA), and E. coli K-12 by disc diffusion, broth microdilution, post-exposure culturability, antimicrobial interactions assessed by checkerboard assay, and GC-MS profiling. Disc diffusion produced no interpretable zones of inhibition for any plant preparation tested; however, broth microdilution revealed reproducible inhibitory activity within published ranges across the panel. Three essential oils achieved a median Minimum Inhibitory Concentration (MIC) of 0.39 mg/mL against MRSA despite presenting compositionally distinct chemotypes: lavender was linalool-dominated (61% combined), lemongrass was citral-dominated (76%), and the doTERRA blend was sesquiterpene-rich. Rosemary ethanolic extract achieved the same potency (0.39 mg/mL) against MSSA. No preparation produced a bactericidal reduction (>=3 log10 CFU/mL) at any timepoint, with all reductions transient and recovering by 24 hours. Checkerboard combinations of plant preparations with vancomycin and ciprofloxacin were uniformly classified, according to the Fractional Inhibitory Concentration Index (FICI), as indifference/no interaction, attributable in part to inoculum-mediated effects on vancomycin MIC. To analyse the relationship between chemical composition and antimicrobial outcomes, we introduce a Chemotype Similarity Index (CSI), a chemometric framework quantifying pairwise compositional similarity between essential oils by Pearson correlation and relating it to log2-MIC differences across strains. CSI revealed a strain-dependent chemistry-activity relationship, convergent against MRSA, monotonic against MSSA, and absent against E. coli, indicating that compositional similarity predicts antimicrobial outcomes on a strain-specific basis. The convergence of three chemotypically divergent essential oils with the same anti-MRSA potency suggested a shared membrane-disrupting mechanism operating through distinct chemical routes. Although exploratory at this scale, the CSI framework provides a reusable analytical scaffold for linking phytochemical composition to antimicrobial activity, and identifies the MRSA convergence as a specific direction for mechanistic investigation into the development of plant-derived antimicrobial adjuncts.

Animals balance staying in a favorable environment with exploring new ones. In C. elegans chemotaxis, the process by which worms migrate toward an attractant has been extensively studied. However, what happens after they reach it remains largely unexplored, partly because conventional assays immobilize worms at the point of arrival. Here, we quantitatively analyzed chemotactic behavior upon reaching an attractive odor source using an immobilization-free chemotaxis assay. We observed that 62% animals left the isoamyl alcohol region after initially approaching it, a behavior we termed "leaving behavior." Quantitative analysis revealed that leaving behavior represents a distinct locomotor state compared with free-moving, high-concentration odor avoidance, and approach behavior. To test whether leaving behavior is related to olfactory adaptation, we analyzed mutants in adaptation-related genes. The proportion of leaving behavior was significantly increased in egl-4 loss-of-function mutants compared with wild-type animals, whereas arr-1 mutants showed no significant difference. These results suggest that egl-4 negatively regulates leaving behavior, suggesting a role for this kinase in stabilizing post-arrival behavioral states beyond its known function in olfactory adaptation. Our findings indicate that chemotaxis involves dynamic behavioral transitions even after reaching an attractant, consistent with an exploration-exploitation trade-off framework.

RationaleAdolescence is a period of heightened vulnerability to nicotine reinforcement. While zebrafish are a valuable model for investigating drug reward, standard conditioned place preference (CPP) assays typically test subjects in isolation. In this highly social species, solitary testing may act as an environmental stressor that confounds behavioral readouts. ObjectivesThis study examined how social context during testing (isolated vs. grouped) affects experimental attrition, behavioral stability, and nicotine CPP expression in late juvenile zebrafish. MethodsZebrafish housed in groups of four were tested either individually (isolated) or in their housing groups (grouped) during daily 20-minute sessions. Following baseline preference assessments, subjects underwent six days of conditioning pairing their initially non-preferred compartment with fish water or nicotine (0.5, 1.6, or 5.0 {micro}mol/L). Place preference, locomotion, and thigmotaxis were assessed on a drug-free test day. ResultsIsolated testing reduced distance traveled, decreased swimming speed, and increased time spent near tank walls, indicating heightened anxiety-like behavior. Experimental attrition was significantly higher in isolated (38.9%) than grouped (2.5%) subjects. Grouped subjects developed significant place preference at 1.6 and 5.0 {micro} mol/L nicotine, whereas preference was not detectable in isolated subjects. ConclusionsSolitary testing acts as a stressor that increases experimental attrition and masks place preference. Conversely, testing in the presence of conspecifics stabilizes behavior and facilitates the detection of nicotine reward in late juvenile zebrafish.

Insecticide treated nets (ITNs) remain one the frontline tool in malaria control in Africa. The synergist piperonyl butoxide (PBO) has been incorporated into ITNs to combat pyrethroid resistance and these pyrethroid-PBO ITNs are now in widespread use across Africa. PBO is known to inhibit the degradation of pyrethroids and other insecticide classes, but little is known about other biological or behavioural effects of PBO exposure. This work assessed the impact of PBO on Anopheles gambiae s.l. male longevity as well as female host-seeking and blood feeding behaviours using laboratory assays. PBO had an immediate impact on blood feeding of female An. gambiae s.l. whereas the effect was not observed 24h post-exposure. Kaplan-Meier survival curves showed a significant difference in mosquito longevity post-exposure to PBO with male mosquitoes living nearly three times as long if exposed to control papers compared to PBO. In olfactometer assays, after exposure to control papers, control mosquitoes were significantly more attracted to host-odours, however, this attraction preference was reversed following PBO exposure. This study shows that in experimental assays, PBO has other effects on mosquito physiology and this is likely to contribute to the impact of pyrethroid - PBO ITNs in vector control programmes.

Transgenerational plasticity can shape plant phenotype and influence plant response to environmental changes in interaction with the current conditions. While how past stress interact with either current optimal or stress conditions is increasingly documented within a single plant, transgenerational plasticity remains particularly poorly understood especially at the metabolome level. In our study, we investigated whether heat stress induces transgenerational metabolic and phenotypic modifications along two successive clonal ramet generations of the sub-Antarctic aquatic plant Limosella australis. We performed untargeted metabolomic approaches and measured morphologic and performance traits, to assess both transgenerational plasticity of the metabolome and the phenotype. We found that heat stress remodelled the metabolic profile and influenced the foraging strategy of our clonal plant, and that some of these metabolic changes persisted into the first clonal generation. This one therefore adopted an intermediate growth strategy, even though culture conditions were optimal. By comparing differentially accumulated features between daughter ramets from heat stressed mother ramets and from unstressed mother ramets, we identified common and specific metabolites accumulation to heat stress response, belonging to diverse compound families. However, we did not observe any adaptative advantage and any metabolic imprint during another heat stress applied on the second clonal generation. This work provides especially new clues into how plant metabolome integrates and transfers previous stressed clonal generation's information.

In turbulent environments, odorants from different sources arrive at different times, potentially providing cues for odor source segregation. In several invertebrate species, short differences in odorant onset enable freely moving animals to discriminate odorant mixtures. In vertebrates, however, studies of sensitivity to odorant onset asynchrony have been conducted under highly constrained sampling conditions, such as with odor delivery tightly coupled to respiration. In this study, we investigated whether domestic dogs could detect odorant onset asynchrony in odorant mixtures under conditions that preserve key features of natural odor sampling. Dogs performed a discrimination task in which odor stimuli were presented as ongoing pulse trains that began independently of animal behavior, avoiding artificial synchronization of odor delivery with sniff cycles. Dogs were trained to discriminate between mixtures of two odorants with synchronous onsets and mixtures with asynchronous onsets. Of the dogs trained, one was able to discriminate odorant onset asynchronies as short as 633 ms. Dogs also displayed sensitivity to auditory stimulus onset asynchrony, discriminating auditory asynchronies as short as 30 ms. These results provide the first demonstration of temporal sensitivity in canine olfaction and the first evidence that vertebrates can use odorant onset asynchrony under conditions that permit free odor sampling.

The marine sponge holobiont, composed of the sponge host and its microbial symbionts, is a known source of abundant and diverse ether lipids (ELs). Apart from their structural role in the cytoplasmic membrane of archaea and some bacteria, ELs have often been linked to signaling functions and defense against pathogens. Despite the relevance of ELs, their biosynthesis, as well as the identity of their producers, remain elusive. Here, we report the analysis of potential ether lipid producing genes and gene clusters, detected in marine sponge metagenomes as well as public sponge genomes. We show that the sponge holobiont has the capacity to synthesize ELs via several pathways, and suggest the ability of the sponge holobiont to synthesize ELs under different O2 levels. Finally, targeted lipidome analysis confirmed that ELs are present in the lipid profiles of all of the studied sponge holobiont samples, and indicates that the biosynthesis of the plasmalogens detected is likely restricted to the sponge host itself, based on the detected hydrocarbon chain lengths. This work provides a basis for the challenging quest to decipher intricate EL biosynthesis in marine sponges and their associated microbes.