Journal of Comparative Physiology A

Nocturnal migration is a remarkable phenomenon observed in many insect species, including moths. Migratory moths are capable of maintaining precise directional orientation during migration, as demonstrated in both laboratory and field studies, suggesting that they use multiple environmental cues for orientation and navigation. Recent studies on Australian Bogong moths revealed that these animals can use stellar cues and likely the geomagnetic field (in conjunction with local visual cues) to select and maintain population-specific migratory direction. However, the underlying orientation mechanisms used by most other migratory moths are still largely unresolved. Further, it remains unclear whether migratory moths can adjust their orientation using Earths magnetic field parameters for determining their position relative to the goal (i.e. location or map information) - an ability clearly shown in some migratory birds which respond to virtual magnetic displacements by correcting their orientation (experiments when animals are exposed to magnetic cues corresponding to other geographic locations). Here, we present results from virtual magnetic displacement experiments conducted on red underwings (Catocala nupta). In addition, we tested their orientation under simulated overcast conditions and in a vertical magnetic field to get indications whether this species relies on geomagnetic or celestial cues to maintain its population-specific migratory direction. Our results show that (1) red underwings did not compensate for virtual magnetic displacement, indicating the absence of a magnetic map; (2) they remained significantly oriented in the absence of geomagnetic information, suggesting the use of a stellar compass; and (3) there was no evidence of magnetic compass orientation in absence of any visual cues.

Multimodal communication plays a central role in animal behavior, particularly when individuals must integrate information from different sensory channels to make rapid decisions. In aquatic environments, chemical and visual cues differ markedly in their spatial and temporal properties, such that chemical signals may be constrained by limited spatial resolution and temporal instability, potentially requiring visual information to reliably guide social decisions. In decapod crustaceans, both cue types are known to mediate reproduction, yet their relative contribution to mate-location behavior remains unclear. Here, we tested how visual and chemical cues from males influence mate-location behavior in females of the prawn Macrobrachium rosenbergii. Females were placed in a central arena and exposed to four stimulus configurations combining visual cues (a life-size photograph of a male or a control background) and chemical cues (water from an aquarium with or without a male). Attraction was quantified as the time spent in each half of the arena. Females showed no directional preference when exposed to chemical cues alone or when visual and chemical cues were spatially incongruent. In contrast, females spent significantly more time near male-associated stimuli only when visual and chemical cues were spatially congruent. These results indicate that mate-location behavior in this species depends on multimodal integration with a strong contextual dependence on visual information, which appears to gate the effectiveness of chemical cues. Spatially congruent multimodal signals are therefore necessary to guide orientation during mate search, suggesting that disruption of visual or chemical information in aquaculture systems may impair mating efficiency.

Vestibular neurons are core elements of the pathways involved in vestibulo-motor functions, such as vestibulo-spinal and vestibulo-ocular reflexes. To meet behavioral needs, electrophysiological neuronal properties are adequately adapted to the sensory-motor computation sustaining these distinct vestibular reflexes. During frog metamorphosis, there is a complete reorganization of the posturo-locomotor system while the oculomotor system remains minimally changed, probably associated to so far unknown changes in vestibular neuronal properties. We used this unique model to investigate the central developmental mechanisms underlying such a reconfiguration of vestibular-associated behaviors. Central vestibular neurons exhibit two types of electrophysiological phenotypes: tonic neurons with a continuous discharge and phasic neurons with a transitory discharge mainly due to the activation of Kv1.1 channel. Electrophysiological recordings and Kv1.1 immunolabeling of vestibulospinal (VS) and vestibulo-ocular (VO) neurons at both larval and juvenile stages revealed that the majority of VS neurons exhibited a tonic discharge in larvae but a phasic discharge in juvenile, while VO neurons remained mainly tonic throughout development. Changes in phasic and tonic neurons proportions in VS population are partly explained by neurogenesis. But we provide evidences that an electrophysiological phenotype switch is a concomitant developmental mechanism participating in the maturation of these central vestibular neurons. All together our results showed that the maturation process in central vestibular neuronal groups is highly related to the metamorphosis-induced remodeling of vestibulo-motor functions they are involved in, with the ultimate purpose of ensuring an adequate adaptation of neuronal elements properties to the developmental changes of behavioral constrains.

Nociception is an essential response for organisms to avoid potential harm and promote survival. Its molecular determinants are largely conserved across Eumetazoa. TRPV receptors are polymodal ion channels exhibiting selective peripheral expression and functional coupling that underpins nociception and pain modulation in complex organisms. However, the execution of protective behaviours triggered by TRPVs is also found in species with a simpler nervous organisation, thus encouraging their investigation in invertebrate model organisms to increase understanding of animal nociception. Cephalopods represent an interesting invertebrate phylum with respect to the evolution of the nervous system, whose complexity suggests it might support pain-like states that exist in vertebrates. This possibility is reflected by the inclusion of cephalopods in the UK and EU animal welfare legislations. Despite this, there is poor characterisation of cephalopod molecular nociceptors. For this reason, we used in silico analysis to identify two TRPV channels in Octopus vulgaris genome (Ovtrpv1 and Ovtrpv2). We validated the putative transcript sequences and highlighted prevalent expression in sensory tissues. We investigated the functional competence of these TRPVs by heterologously expressing Ovtrpv1 and Ovtrpv2 cDNA into Caenorhabditis elegans null mutants of the orthologous genes, ocr-2 and osm-9 respectively. Ovtrpvs successfully rescued the aversive response to chemical and mechanical noxious stimuli in the C. elegans mutants, suggesting these receptors are polymodal nociceptors. Additionally, complementary investigation using Xenopus laevis oocytes showed Ovtrpv1 and Ovtrpv2 form an active heteromeric channel gated by nicotinamide. This study highlights Ovtrpvs as an important route to better understand nociceptive detection in cephalopods.

Triatomines are the vectors of Chagas disease, one of the main endemic diseases from South to North America, now expanding to other continents. These hemimetabolous insects have been considered poorly visual animals. However, recent findings challenge this idea. Here, we used Rhodnius prolixus as a model species to comprehensively characterize triatomine compound eyes. We found that in the adult stage, eye size significantly exceeds the dimensions predicted by the nymphal eye growth rate. Moreover, while the compound eye grows symmetrically in its dorsal and ventral directions throughout the nymphal instars, in the adult, the eye undergoes greater ventral growth, resulting in a dorsoventrally asymmetrical eye. By studying a bright pseudopupil induced by fluorescence in natural mutant animals, we observed no major differences in sampling resolution between the last nymphal instar and the adult stage. However, the adult eye possesses significantly larger ommatidia, particularly in its ventral region, shifting the area of highest sensitivity from the equatorial region in the nymphal instars to the ventral region in the adult. A similar eye growth pattern was observed in Triatoma infestans and Panstrongylus megistus. The analysis of photographic records from 39 species across 10 genera indicates that an asymmetrical eye is the predominant eye pattern in adult triatomines. Notable exceptions in wingless adults of Mepraia spinolai, reveal a tight association between possessing a large asymmetrical eye and the presence of wings. This suggests that vision might support triatomine dispersal flights among other visual behaviors. Significance StatementKissing bugs are hematophagous insects known for being the vectors of Chagas disease, one of the main endemic diseases in the Americas. Vision was not considered a relevant sensory system in these insects. Here, we show that their eyes increase in size beyond expected by ontogeny and become asymmetrical when transitioning from the last nymphal instar to the adult stage. The eyes undergo a ventral expansion that shifts the region of greatest light sensitivity from the equatorial zone in nymphs to the ventral region in adults. We found this asymmetrical eye only in winged kissing bugs, suggesting that vision supports flight. This is relevant in ecological and epidemiological terms since kissing bugs disperse by flight for habitat colonization and host-seeking.

O_LIEctotherms in thermally variable environments mediate energy expenditure through both physiological and behavioural responses. However, many studies focus on constant temperature acclimation, and few consider behaviour and physiology in unison. It is unclear how acclimation to thermal variability affects locomotory choices, activity timing, and performance across daily thermal cycles. C_LIO_LIWe investigated the effects of thermal variability in the temperate dung beetle Onthophagus taurus. Following acclimation to a low amplitude (22{degrees}C {+/-} 2{degrees}C) or a high amplitude (22{degrees}C {+/-} 10{degrees}C) temperature regime, we measured behaviour and metabolic rate across temperatures. We hypothesised that O. taurus adjusts its locomotive strategy and search window when kept in high amplitude fluctuating temperatures to reduce energy loss associated with high temperature exposure. C_LIO_LIWe found that differences in energy expenditure were determined by propensity for flight which differed between acclimation treatments, particularly at intermediate temperatures. We also found that, following acclimation to a high amplitude of thermal variability, O. taurus exhibited a greater intensity of activity over a narrower window of time, and O. taurus acclimated to a low amplitude of thermal variability showed nocturnal activity. C_LIO_LIWe then used the data to model activity through the growing season over five years. Biophysical models were built using NicheMapR Microclimate and Ectotherm functions to test the length of potential searching time across seasons, the temperatures individuals are exposed, and locomotive strategy. Model outputs showed that acclimation to higher amplitudes of thermal variability increased accumulated degree-hours of activity relative to the low variability acclimation group. Individuals acclimated to higher amplitudes of thermal variability showed greater accumulated degree-hours in spring and fall, but exhibited shorter periods of activity during summer, with the model predicting increased opportunities for flight. Comparatively, O. taurus from the low variability acclimation treatment showed increased night activity in summer but did not fly. C_LI

OverviewThis dataset originates from a preliminary respirometry study on carabid beetles from the Elbe Estuary (Northern Germany), encompassing species from freshwater and saltmarsh habitats along a salinity gradient. The study was designed to establish and validate a workflow for measuring oxygen consumption, including chamber setup, sensor recording, drift correction, and calculation of absolute and mass-specific metabolic rates. Oxygen consumption was measured for five species (Carabus auratus, Carabus granulatus, Limodromus assimilis, Poecilus versicolor and Pterostichus niger) using sealed glass vials connected to an optical oxygen system. The dataset provides individual-level measurements and serves primarily as a methodological reference for future respirometry studies on ground-dwelling arthropods. The O2 consumption rates of carabid beetles showed interspecific differences and followed metabolic scaling theory, revealing an inverse relationship between body mass and mass-specific metabolic rates across species (Figure 3). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/720111v1_fig3.gif" ALT="Figure 3"> View larger version (17K): org.highwire.dtl.DTLVardef@f41f27org.highwire.dtl.DTLVardef@12939eeorg.highwire.dtl.DTLVardef@19a4630org.highwire.dtl.DTLVardef@17611ba_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 3:C_FLOATNO Oxygen consumption rates of Carabid species per (a) animal in [ml O2 h-1] and as (b) mass-specific consumption rate [ml O2 h-1 g-1]. Points represent mean oxygen consumption per individual (C. auratus: n = 2; L. assimilis: n = 6; P. versicolor: n = 7; P. niger: n = 6). C_FIG

Iron is an essential nutrient for all types of organisms, including insects and the microbes that infect them. We predicted that insects fed an iron-supplemented diet would accumulate more iron in their hemolymph, and, because infectious microbes acquire iron from their hosts, that this extra iron would increase the severity of bacterial infections. To test this hypothesis, we studied the effects of dietary iron supplementation on infection outcomes in Manduca sexta (tobacco hornworm). Larvae were fed an artificial diet, with or without antibiotics, or the same diets supplemented with 10 mM iron. Control and iron-treated larvae were inoculated with non-pathogenic Escherichia coli or the entomopathogenic Enterococcus faecalis, and bacterial load and larval survival were measured. We found that dietary iron supplementation increased the iron content of hemolymph by approximately 20 fold; however, contrary to our prediction, this increase in iron did not result in an increase in the bacterial load of either E. coli or E. faecalis. The effect of iron supplementation on survival was more complicated. As expected, for larvae inoculated with nonpathogenic E. coli, iron supplementation had no effect. For larvae inoculated with E. faecalis, the effect of iron supplementation depended on whether antibiotics were present in the diet. Without antibiotics, iron supplementation prolonged larval survival; with antibiotics, iron supplementation decreased larval survival. The results of this study do not support the hypothesis that dietary iron supplementation increases infection severity in M. sexta. Instead, the results support the viewpoint that the relationship between dietary iron and infection outcome is complex.

Nocturnal moths are severely affected by light pollution, most notoriously through fatal attraction to artificial lights, yet flight-to-light is not their only response. To investigate how artificial lights impact flight behaviour, we exposed over 1200 wild-caught moths of 62 species to LED lights with different characteristics, under varying background lighting conditions, and tracked over 500 flight paths in three dimensions. Flight-to-light behaviour and flight tortuosity both increased with light intensity, irrespective of spectrum, though tortuosity was affected by lower levels of white than amber light, suggesting white LEDs could impact moth trajectories from greater distances. Flight tortuosity was also higher upon exposure to a single light versus three producing equivalent illuminance. Conversely, higher background light levels led to reductions in both flight-to-light and tortuosity, but moths were also less likely to take flight in these conditions, suggesting that both point sources and diffuse background lighting disrupt moth movement. Finally, moths caught using light traps were less likely to fly and, if they did, more likely to fly towards light sources than those caught with butterfly nets. These findings suggest mitigation policies for light pollution should prioritize reducing light intensity, and point to new directions for future research.

The rat vestibular system plays a critical role in anti-gravity responses such as the tail-lift reflex and the air-righting reflex. In a previous study in male rats, we obtained evidence that these two reflexes depend on the function of non-identical populations of vestibular sensory hair cells (HC). Here, we caused graded lesions in the vestibular system of female rats by exposing the animals to several different doses of an ototoxic chemical, 3,3-iminodipropionitrile (IDPN). After exposure, we assessed the anti-gravity responses of the rats and then assessed the loss of type I HC (HCI) and type II HC (HCII) in the central and peripheral regions of the crista, utricle and saccule. As expected, we recorded a dose-dependent loss of vestibular function and loss of HCs. The relationship between hair cell loss and functional loss was examined using non-linear models fitted by orthogonal distance regression. The results indicated that both the tail-lift reflex and the air-righting reflexes mostly depend on HCI function. However, a different dependency was found on the epithelium triggering the reflex: while the tail-lift response is sensitive to loss of crista and/or utricle HCIs, the air-righting response rather depends on utricular and/or saccular integrity.

In natural environments, animals must effectively maneuver around obstacles to reach goals such as food or shelter. Recent work has demonstrated that laboratory mice use vision for naturalistic behavior such as prey capture, escape, and distance estimation. However, it is unknown to what extent mice use vision relative to other senses such as touch for obstacle avoidance, a critical natural behavior. In this study we developed an obstacle avoidance task in freely moving mice to investigate how vision is used to guide paths around an obstacle obstructing a goal. We found that mice clearly use vision to avoid an obstacle, steering around the obstacle at distances where tactile information isnt available. By comparing trajectories for mice performing obstacle avoidance in the light versus the dark, we found that vision contributes to more spatially efficient trajectories and paths directed to the open edge of the obstacle. When vision is available, mice make large orienting movements towards the opening of the obstacle at about 10 cm from its edge, suggesting that mice are actively using visual information to direct these movements. Finally, by occluding one eye, we found that mice were still able to avoid obstacles with primarily monocular information. Taken together, these results demonstrate that laboratory mice use vision to avoid an obstacle, taking directed paths that are initiated by large orienting movements. In addition to demonstrating the visual behavioral capabilities of the mouse, this paradigm can serve as a foundation to study the neural circuits that mediate visually guided orienting and locomotion. HighlightsO_LIWe developed a simple obstacle avoidance task for freely moving mice that requires minimal training C_LIO_LIVision is necessary for efficient and directed paths around an obstacle C_LIO_LIMice steer around obstacles by performing directed head movements towards clear paths C_LIO_LIMice do not require binocular vision for obstacle avoidance C_LI

Recent studies have shown that symbiotic bacteria can have drastic effects on host neurobiology, but few simple, accessible models currently exist in which to study these interactions. Hawaiian bobtail squid (Euprymna scolopes) participate in a binary symbiosis with the bacterium Vibrio fischeri, a population of which resides in a specialized hindgut-derived organ called the light organ. Upon colonization by V. fischeri, the light organ undergoes transcriptional changes that suggest neurons are impacted by the initiation of symbiosis, but the nascent light organs innervation has remained uncharacterized. Here, we show that the light organ-associated nervous system (LONS) in hatchling E. scolopes is a remarkably complex segment of the peripheral nervous system. The LONS is largely plexiform and originates from two primary nerves connected by a local commissure. The abundance of synapsin-like immunoreactivity (-lir) indicates that the lobe plexus is highly interconnected. We also highlight a small number of serotonin-lir neurites that innervate the anterior appendages whose developmental fate may be directly affected by symbiont-driven light organ morphogenesis. Finally, we present evidence that a limited but diverse population of neurons reside within the light organ and are often located near internal symbiont-interacting structures. This description of the E. scolopes LONS serves to provide a foundation from which to investigate how beneficial bacterial symbionts affect host peripheral neurobiology in a tractable model system.

The ability of animals to innovate - solve novel problems - can shape their ecology and evolution. Here we investigate how individual traits and environmental complexity relate to successful solving of a novel problem. We presented foraging bumble bees (Bombus impatiens) with artificial flowers of not-previously-encountered shapes and recorded the bees latency to access nectar. We measured individual foraging traits across multiple trips with simple flowers that did not require innovation, and bees were foraging either in a simple or complex environment (cluttered flight arena). Bees in complex environments took longer to find and were less likely to land on novel flowers, indicating that environmental complexity may take up cognitive resources and make search more difficult. However, we did not find an effect of environmental treatment on the ability or time to access reward in novel flowers once bees had landed on them. In contrast, behavioral traits significantly predicted how quickly bees solved novel flowers. In particular, overall foraging tempo as well as routine formation, i.e. how much bees followed a fixed route on known flowers, predicted innovation - faster bees innovated faster, and bees with more repetitive foraging sequences were slower to solve the novel tasks. Overall, while the degree of evolutionary novelty in tasks or solutions is always hard to evaluate, our findings demonstrate that environment and individual traits may affect innovation in different ways. Individuals in simple environments may be more likely to detect, and individuals that are generally faster and have a lower tendency to develop fixed routines may be more likely to solve, novel tasks.

Animals often aggregate information from multiple different sensory modalities to accurately assess and react to a stimulus. It is often assumed that cross-modality integration mostly occurs at high-level processing centers, such as the mammalian cortex or insect mushroom bodies. However, we hypothesized that integration could occur relatively early in the sensory pathways. The insect antennal lobe is one such location, receiving direct inputs from the antennae via the antennal nerve. These inputs are highly multimodal, including olfactory, mechanosesnory, and gustatory information, all of which are relevant to foraging honeybees (Apis mellifera). Here we assess integration by recording electrophysiological spike data within the honeybee antennal lobe while exposing the bee to various combinations of wind speed and odor concentration. This paper accompanies another publication by Joseph Reed and Mainak Patel approaching the same question from a modelling perspective, where their model corroborates our data and vice versa. Together, we show that integration occurs within this early layer of processing, while also demonstrating the complex relationship of these two closely-linked stimuli. SIGNIFICANCEAccurate perception depends on the brains ability to combine information from multiple senses, commonly thought belonging to high level of information processing. Using the European honeybee, Apis mellifera, we show strong evidence that olfactory and mechanosensory signals interact at an early stage of neural processing, within the antennal lobe, producing stimulus representations closely-linked to the animals navigation and decision-making. By identifying a tractable model for early multisensory processing, this work offers broader insight into how animals construct reliable representations of their environment.

Settlement, the transition of a swimming planktonic larva to a crawling or sessile benthic juvenile, is a key process in the development of many marine invertebrates. Successful recruitment via larval settlement is critical for the development and maintenance of seafloor ecosystems. Microbial biofilms act as positive cues for larval settlement across diverse taxa, yet the behavioural processes preceding settlement are poorly understood. Here, we investigated age-dependent changes in settlement behaviour in the marine polychaete Platynereis dumerilii larvae in response to Grammatophora marina diatom biofilms. Settlement behaviours (crawling, crawling speed, and track straightness (tortuosity)) were quantified from recordings of larvae at five developmental stages (mid-trochophore to late-nectochaete) in the presence or absence of diatom biofilms, using image segmentation and spot-tracking software. As larvae developed, the proportion of individuals crawling (settlement) over the biofilm increased. Older larvae colonised biofilms more rapidly and showed greater discrimination between G. marina biofilms and non-biofilmed controls. The movement trajectory of older larvae also straightens compared to individuals swimming in the presence of biofilms, or behaviour witnessed in the absence of biofilms. The proportions and magnitudes of these behaviours may reflect changing prioritisation of sensory inputs from physical and chemical cues as larvae develop. Our findings suggest that behavioural traits that are associated with settlement are developmentally programmed in P. dumerilii. Understanding settlement behaviours in P. dumerilii expands on this species behavioural repertoire and sheds light on the evolutionary relationship between marine larvae and microalgal biofilms.

Climate warming alters the thermal environment experienced by ectotherms, whose physiological performance and fitness are constrained by temperature. Early life stages are often the temperature-sensitive phases of the life cycle, with potential consequences for population persistence, particularly in freshwater stenotherms such as the Arctic charr (Salvelinus alpinus). The persistence of populations will partly depend on the adaptive potential of critical life stages to environmental changes. In this study, we used a common garden approach to compare the response and phenotypic plasticity of four charr populations to warmer conditions. These populations inhabit thermally contrasted lakes and differ in origin (native/introduced) and management history. We reared embryos at either an optimal (5{degrees}C) temperature for larval development or a warmer but realistic (8.5 {degrees}C) temperature. We tested adaptive divergence among populations in four traits (survival, incubation duration, body length and yolk sac volume), using Qst - Fst comparisons. We report negative effects of temperature on body size, survival and earlier hatching. Thermal reaction norms differed among populations, indicating adaptive divergence. Contrary to expectations, populations originating from warmer environments did not consistently exhibit higher trait values under elevated temperatures. In contrast, the unmanaged and colder high-altitude population exhibited higher survival rates and lower yolk reserves for a given size under heat stress than the other populations. Our results suggested that evolutionary trajectories specific to each population are shaped by factors related to the populations history, including introductions, demographic fluctuations and long-term repopulation practices, which can jointly influence the potential for adaptation to heat stress.

Finding resources for the colony is one of the most difficult and risky tasks for a social insect worker. A worker on a foraging trip can face a number of challenges, including interference from other individuals, her own errors, and environmental disturbances. Collectively, colonies may use a variety of strategies to minimize the impact of such perturbations on the foraging process. Here, we investigated how individual Solenopsis xyloni ant workers react to perturbation of an established pheromone trail. We trained foragers from colonies in the field to either a low or high concentration sucrose solution in a feeder on a T-maze setup, then replaced a section of floor covering, removing a section of the pheromone trail previously laid. We found that while ants made correct choices on the T-maze when the trail was intact, their choices did not differ from chance when the trail was absent, indicating strong reliance on a pheromone trail (and not, for example, memory) to return to the resource. Moreover, when the trail was absent, we found that a majority of ants abandoned the resource, and that even the ants that were able to reach the resource did not repair the perturbed trail. However, with a high-quality resource, more ants persisted in attempting to reach it (instead of abandoning). We interpret these responses in the framework of robustness mechanisms discussed in systems biology. Our study thus links individual and collective responses to perturbations, and provides an empirical example of how information use interacts with system robustness. Statements and declarationsThe authors have no competing interests to declare that are relevant to the content of this article.

Many marine invertebrates are characterized by broad and highly plastic thermal limits, though the dynamic molecular mechanisms that enable extended thermal acclimation remain poorly understood. A classic example is the green crab (Carcinus maenas), which is a prolific and damaging non-indigenous species. Using a 22-day thermal exposure to cold (5{degrees}C), ambient (13{degrees}C), or warm (30{degrees}C) temperatures, we characterized plastic shifts in C. maenas performance using respirometry and time-to-right. We then used untargeted metabolomics and lipidomics analysis of heart tissues from days 4 and 22 to identify the molecular mechanisms underpinning plastic responses over time. Crabs at 30{degrees}C exhibited higher oxygen consumption rates than counterparts at 5{degrees}C. Interestingly, oxygen consumption rate increased over time at both temperatures, indicating thermal plasticity of aerobic respiration. Temperature-dependent metabolic reprogramming was employed by crabs to sustain aerobic respiration across temperature. Catabolism of branched-chain amino acids was important for energy production at elevated temperatures, while catabolism of arginine may have sustained the minimal energy needs of crabs exhibiting metabolic depression at cold temperatures. Righting response was positively correlated with temperature, and did not exhibit any changes over time. Lipidome remodeling consistent with homeoviscous adaptation could have enabled motor activity across temperature. Higher abundances of saturated and monounsaturated lipids likely provided structural integrity to cell membranes at 30{degrees}C, while lower abundances of these compounds may have enabled membrane fluidity at 5{degrees}C. Our work demonstrates the importance of ongoing molecular reprogramming in long-term acclimation, even when whole-animal physiology remains relatively stable. Summary StatementThis study demonstrates how the highly invasive green crab regulates metabolite and lipid pathways over time to maintain physiological performance across different temperatures.

Organisms must be able to maintain the ability to produce high quality offspring despite experiencing stressful conditions. It is unknown how C. elegans maintain the ability to produce offspring during moderate temperature stress just below the range of temperature that cause sterility. We evaluated apoptosis, fertility, and several progeny fitness metrics in no-apoptosis, high-apoptosis mutants, and in wild strains that varied in their fertility level during moderate temperature stress to understand if apoptosis is a strategy C. elegans use to maintain the ability to produce offspring during a moderate temperature stress. We found that apoptosis mutants were less fertile with less fit progeny compared to wild type under a moderate temperature stress. Wild strains isolated from the environment showed variability in the increase in apoptosis, levels of fertility, and measurements of progeny fitness observed. We also found that an intermediate induction of apoptosis trended with higher fertility and progeny fitness in wild strains under a moderate temperature tress. These results suggest that apoptosis within an optimal range in the C. elegans germline is a strategy used to maintain the ability to produce high quality offspring despite experiencing a moderate temperature stress. Many species also have germline apoptosis, so apoptosis may be a strategy other species use to maintain their own fertility when experiencing stress conditions

The human auditory system decomposes complex sounds into distinct components via a collection of processing steps. Knowing whether Spiral Ganglion Cells (SGCs) play an active role in the decoding of complex sounds can facilitate the development of Cochlear Implant (Cl) coding strategies and clinical assessment tools. Early animal studies reported SGCs being similar across different characteristic frequencies (CFs). In this study, human electrically evoked compound action potentials (eCAPs) were analysed to probe the relationship between the reciprocal of CF and the duration of the eCAP. A significant relationship could indicate that SGCs may not simply be passive cables. eCAP datasets from 6 published studies (175 Cl users, 1243 recordings) were analysed and their peaks were automatically labelled. The nlp2 latency was derived for each recording as a proxy of the action potential duration. The CF of each recording was estimated by mapping the average insertion angle of the electrode to the human SGC map. A weak but statistically significant relationship was observed between the n1p2 latency and the reciprocal of CF (random-effects model with random intercepts for subject, r = 0.09, p = 0.024, n= 450) supporting the hypothesis that lower CF is associated with slower repolarisation (longer n1p2 latency) in human spiral ganglion cells.