nils-herrmann/clean_scirepeval huggingface dataset:
Catch-up growth in Japanese quail (Coturnix Japonica): relationships with food intake, metabolic rate and sex
Venue: Journal of Comparative Physiology B

The effects of early environmental conditions can profoundly affect individual development and adult phenotype. In birds, limiting resources can affect growth as nestlings, but also fitness and survival as adults. Following periods of food restriction, individuals may accelerate development, undergoing a period of rapid “catch-up” growth, in an attempt to reach the appropriate size at adulthood. Previous studies of altricial birds have shown that catch-up growth can have negative consequences in adulthood, although this has not been explored in species with different developmental strategies. Here, we investigated the effects of resource limitation and the subsequent period of catch-up growth, on the morphological and metabolic phenotype of adult Japanese quail (Coturnix japonica), a species with a precocial developmental strategy. Because males and females differ in adult body size, we also test whether food restriction had sex-specific effects. Birds that underwent food restriction early in development had muscles of similar size and functional maturity, but lower adult body mass than controls. There was no evidence of sex-specific sensitivity of food restriction on adult body mass; however, there was evidence for body size. Females fed ad lib were larger than males fed ad lib, while females subjected to food restriction were of similar size to males. Adults that had previously experienced food restriction did not have an elevated metabolic rate, suggesting that in contrast to altricial nestlings, there was no metabolic carry-over effect of catch-up growth into adulthood. While Japanese quail can undergo accelerated growth after re-feeding, timing of food restriction may be important to adult size, particularly in females. However, greater developmental flexibility compared to altricial birds may contribute to the lack of metabolic carryover effects at adulthood.
Use of a light-dependent magnetic compass for y-axis orientation in European common frog (Rana temporaria) tadpoles
Venue: Journal of Comparative Physiology A

We provide evidence for the use of a magnetic compass for y-axis orientation (i.e., orientation along the shore-deep water axis) by tadpoles of the European common frog (Rana temporaria). Furthermore, our study provides evidence for a wavelength-dependent effect of light on magnetic compass orientation in amphibians. Tadpoles trained and then tested under full-spectrum light displayed magnetic compass orientation that coincided with the trained shore-deep water axes of their training tanks. Conversely, tadpoles trained under long-wavelength (≥500 nm) light and tested under full-spectrum light, and tadpoles trained under full-spectrum light and tested under long-wavelength (≥500 nm) light, exhibited a 90° shift in magnetic compass orientation relative to the trained y-axis direction. Our results are consistent with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength (≥500 nm) light is due to a direct effect of light on the underlying magnetoreception mechanism. These findings also show that wavelength-dependent effects of light do not compromise the function of the magnetic compass under a wide range of natural lighting conditions, presumably due to a large asymmetry in the relatively sensitivity of antagonistic short- and long-wavelength inputs to the light-dependent magnetic compass.
Physiological and biochemical responses to cold and drought in the rock-dwelling pulmonate snail, Chondrina avenacea
Venue: Journal of Comparative Physiology B

The pulmonate snail Chondrina avenacea lives on exposed rock walls where it experiences drastic daily and seasonal fluctuations of abiotic conditions and food availability. We found that tolerance to dry conditions was maintained at a very high level throughout the year and was mainly based on the snails’ ability to promptly enter into estivation (quiescence) whenever they experienced drying out of their environment. Snails rapidly suppressed their metabolism and minimized their water loss using discontinuous gas exchange pattern. The metabolic suppression probably included periods of tissue hypoxia and anaerobism as indicated by accumulation of typical end products of anaerobic metabolism: lactate, alanine and succinate. Though the drought-induced metabolic suppression was sufficient to stimulate moderate increase of supercooling capacity, the seasonally highest levels of supercooling capacity and the highest tolerance to subzero temperatures were tightly linked to hibernation (diapause). Hibernating snails did not survive freezing of their body fluids and instead relied on supercooling strategy which allowed them to survive when air temperatures dropped to as low as −21 °C. No accumulation of low-molecular weight compounds (potential cryoprotectants) was detected in hibernating snails except for small amounts of the end products of anaerobic metabolism.
Audio–vocal interactions during vocal communication in squirrel monkeys and their neurobiological implications
Venue: Journal of Comparative Physiology A

Several strategies have evolved in the vertebrate lineage to facilitate signal transmission in vocal communication. Here, I present a mechanism to facilitate signal transmission in a group of communicating common squirrel monkeys (Saimiri sciureus sciureus). Vocal onsets of a conspecific affect call initiation in all other members of the group in less than 100 ms. The probability of vocal onsets in a range of 100 ms after the beginning of a vocalization of another monkey was significantly decreased compared to the mean probability of call onsets. Additionally, the probability for vocal onsets of conspecifics was significantly increased just a few hundreds of milliseconds after call onset of others. These behavioral data suggest neural mechanisms that suppress vocal output just after the onset of environmental noise, such as vocalizations of conspecifics, and increase the probability of call initiation of group mates shortly after. These findings add new audio–vocal behaviors to the known strategies that modulate signal transmission in vocal communication. The present study will guide future neurobiological studies that explore how the observed audio–vocal behaviors are implemented in the monkey brain.
Hypoxia impairs visual acuity in snapper (Pagrus auratus)
Venue: Journal of Comparative Physiology A

We investigated the effect of environmental hypoxia on vision in snapper (Pagrus auratus). Juvenile snapper inhabit estuarine environments where oxygen conditions fluctuate on a seasonal basis. Optomotor experiments demonstrated that visual acuity is impaired by environmental hypoxia, but not until levels approach the critical oxygen tension (Pcrit) of this species (around 25 % air-saturated seawater). In 100, 80, and 60 % air-saturated seawater, a positive optomotor response was present at a minimum separable angle (MSA) of 1°. In 40 % air-saturated seawater, vision was partially impaired with positive responses at MSAs of 2° and above. However, in 25 % air-saturated seawater, visual acuity was seriously impaired, with positive responses only present at MSAs of 6° and above. Snapper were found to possess a choroid rete, facilitating the maintenance of high ocular oxygen partial pressures (PO2) during normoxia and moderate hypoxia (PO2, between 269 and 290 mmHg). However, at 40 and 25 % water oxygen saturation, ocular PO2 was reduced to below 175 mmHg, which is perhaps linked to impairment of visual acuity in these conditions. The ability to preserve visual function during moderate hypoxia is beneficial for the maintenance of a visual lifestyle in the fluctuating oxygen environments of estuaries.
Neuronal encoding of sound, gravity, and wind in the fruit fly
Venue: Journal of Comparative Physiology A

The fruit fly Drosophila melanogaster responds behaviorally to sound, gravity, and wind. Exposure to male courtship songs results in reduced locomotion in females, whereas males begin to chase each other. When agitated, fruit flies tend to move against gravity. When faced with air currents, they ‘freeze’ in place. Based on recent studies, Johnston’s hearing organ, the antennal ear of the fruit fly, serves as a sensor for all of these mechanosensory stimuli. Compartmentalization of sense cells in Johnston’s organ into vibration-sensitive and deflection-sensitive neural groups allows this single organ to mediate such varied functions. Sound and gravity/wind signals sensed by these two neuronal groups travel in parallel from the fly ear to the brain, feeding into neural pathways reminiscent of the auditory and vestibular pathways in the human brain. Studies of the similarities between mammals and flies will lead to a better understanding of the principles of how sound and gravity information is encoded in the brain. Here, we review recent advances in our understanding of these principles and discuss the advantages of the fruit fly as a model system to explore the fundamental principles of how neural circuits and their ensembles process and integrate sensory information in the brain.
A review of the thermal sensitivity of the mechanics of vertebrate skeletal muscle
Venue: Journal of Comparative Physiology B

Environmental temperature varies spatially and temporally, affecting many aspects of an organism’s biology. In ectotherms, variation in environmental temperature can cause parallel changes in skeletal muscle temperature, potentially leading to significant alterations in muscle performance. Endotherms can also undergo meaningful changes in skeletal muscle temperature that can affect muscle performance. Alterations in skeletal muscle temperature can affect contractile performance in both endotherms and ectotherms, changing the rates of force generation and relaxation, shortening velocity, and consequently mechanical power. Such alterations in the mechanical performance of skeletal muscle can in turn affect locomotory performance and behaviour. For instance, as temperature increases, a consequent improvement in limb muscle performance causes some lizard species to be more likely to flee from a potential predator. However, at lower temperatures, they are much more likely to stand their ground, show threatening displays and even bite. There is no consistent pattern in reported effects of temperature on skeletal muscle fatigue resistance. This review focuses on the effects of temperature variation on skeletal muscle performance in vertebrates, and investigates the thermal sensitivity of different mechanical measures of skeletal muscle performance. The plasticity of thermal sensitivity in skeletal muscle performance has been reviewed to investigate the extent to which individuals can acclimate to chronic changes in their thermal environment. The effects of thermal sensitivity of muscle performance are placed in a wider context by relating thermal sensitivity of skeletal muscle performance to aspects of vertebrate species distribution.
Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes
Venue: Journal of Comparative Physiology A

Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species. This may be associated with differences in ambient light intensity while foraging or an ability to tightly constrict the pupil in divers in order to facilitate underwater vision. Retinal topography was similar across all species, consisting of an oblique visual streak, a central area of peak cell density, and no discernible fovea. Because the bill faces downwards when the head is held in the normal posture in waterfowl, the visual streak will be held horizontally, allowing the horizon to be sampled with higher visual acuity. Estimates of spatial resolving power were similar among species with only the Canada goose having a higher spatial resolution. Overall, we found no evidence of ecomorphological adaptations to different foraging modes in the retinal ganglion cell layer in waterfowl. Rather, retinal topography in these birds seems to reflect the ‘openness’ of their habitats.
Serotonin precursor (5-hydroxytryptophan) causes substantial changes in the fighting behavior of male crickets, Gryllus bimaculatus
Venue: Journal of Comparative Physiology A

This study demonstrates that injection of the serotonin precursor 5-HTP causes substantial changes in the behavioral state, fighting behavior and ability to establish winner–loser relationships in male crickets (Gryllus bimaculatus). The characteristic features of 5-HTP-treated crickets include an elevated posture, enhanced general activity, longer duration of fighting, enhanced rival singing and a decreased ability to produce a clear fight loser. In addition, 5-HTP-treated males showed a slightly delayed latency to spread their mandibles, a decreased number of attacks and an equal potential to win in comparison to controls (physiological solution-treated males). The obtained results imply a significant role for serotonin in the regulation of social status-related behaviors in G. bimaculatus. Specifically, these data indicate that a decrease in serotonergic activity may be functionally important for the control of loser behavior and that some behavioral features of dominant male crickets are likely to be connected with the activation of the serotonergic system.
Does low daily energy expenditure drive low metabolic capacity in the tropical robin, Turdus grayi?
Venue: Journal of Comparative Physiology B

Temperate and tropical birds possess divergent life history strategies. Physiological parameters including energy metabolism correlate with the life history such that tropical species with a slower ‘pace of life’ have lower resting and maximal metabolic rates than temperate congeners. To better understand the physiological mechanisms underlying these differences, we investigated the relationship of metabolic capacity, muscle oxidative capacity and activity patterns to variation in life history patterns in American robins (Turdus migratorius), while resident in central North America and Clay-colored robins (Turdus grayi) resident in Panama. We measured summit metabolism $$ \left( {\dot{V}{\text{O}_{2\text{summit}}}} \right) $$ in birds from both tropical and temperate habitats and found that the temperate robins have a 60 % higher metabolic capacity. We also measured the field metabolic rate (FMR) of free-living birds using heart rate (HR) telemetry and found that temperate robins’ daily energy expenditure was also 60 % higher. Thus, $$\dot{V}{\text{O}_{2\text{summit}}} $$ and FMR both reflect life history differences between the species. Further, both species operate at a nearly identical ~50 % of their thermogenic capacity throughout a given day. As a potential mechanism to explain differences in activity and metabolic capacity, we ask whether oxidative properties of flight muscle are altered in accordance with life history variation and found minimal differences in oxidative capacity of skeletal muscle. These data demonstrate a close relationship between thermogenic capacity and daily activity in free-living birds. Further, they suggest that the slow pace of life in tropical birds may be related to the maintenance of low activity rather than functional capacity of the muscle tissue.
Calcium responses of circadian pacemaker neurons of the cockroach Rhyparobia maderae to acetylcholine and histamine
Venue: Journal of Comparative Physiology A

The accessory medulla (aMe) is the pacemaker that controls circadian activity rhythms in the cockroach Rhyparobia maderae. Not much is known about the classical neurotransmitters of input pathways to the cockroach circadian system. The circadian pacemaker center receives photic input from the compound eye, via unknown excitatory and GABAergic inhibitory entrainment pathways. In addition, neuropeptidergic inputs couple both pacemaker centers. A histamine-immunoreactive centrifugal neuron connects the ventral aMe with projection areas in the lateral protocerebrum and may provide non-photic inputs. To identify neurotransmitters of input pathways to the circadian clock with Fura-2-dependent Ca2+ imaging, primary cell cultures of the adult aMe were stimulated with acetylcholine (ACh), as the most prominent excitatory, and histamine, as common inhibitory neurotransmitter. In most of aMe neurons, ACh application caused dose-dependent increases in intracellular Ca2+ levels via ionotropic nicotinic ACh receptors. These ACh-dependent rises in Ca2+ were mediated by mibefradil-sensitive voltage-activated Ca2+ channels. In contrast, histamine application decreased intracellular Ca2+ levels in only a subpopulation of aMe cells via H2-type histamine receptor chloride channels. Thus, our data suggest that ACh is part of the light entrainment pathway while histamine is involved in a non-photic input pathway to the ventral circadian clock of the Madeira cockroach.
Function and central projections of gustatory receptor neurons on the antenna of the noctuid moth Spodoptera littoralis
Venue: Journal of Comparative Physiology A

Chemosensory information is crucial for most insects to feed and reproduce. Olfactory signals are mainly used at a distance, whereas gustatory stimuli play an important role when insects directly contact chemical substrates. In noctuid moths, although the antennae are the main olfactory organ, they also bear taste sensilla. These taste sensilla detect sugars and hence are involved in appetitive learning but could also play an important role in food evaluation by detecting salts and bitter substances. To investigate this, we measured the responses of individual taste sensilla on the antennae of Spodoptera littoralis to sugars and salts using tip recordings. We also traced the projections of their neuronal axons into the brain. In each sensillum, we found one or two neurons responding to sugars: one NaCl-responsive and one water-sensitive neuron. Responses of these neurons were dose-dependent and similar across different locations on the antenna. Responses were dependent on the sex for sucrose and on both sex and location for glucose and fructose. We did not observe a spatial map for the projections from specific regions of the antennae to the deutocerebrum or the tritocerebrum/suboesophageal ganglion complex. In accordance with physiological recordings, back-fills from individual sensilla revealed up to four axons, in most cases targeting different projection zones.
Velarium control and visual steering in box jellyfish
Venue: Journal of Comparative Physiology A

Directional swimming in the box jellyfish Tripedalia cystophora (cubozoa, cnidaria) is controlled by the shape of the velarium, which is a thin muscular sheet that forms the opening of the bell. It was unclear how different patterns of visual stimulation control directional swimming and that is the focus of this study. Jellyfish were tethered inside a small experimental tank, where the four vertical walls formed light panels. All four panels were lit at the start of an experiment. The shape of the opening in the velarium was recorded in response to switching off different combinations of panels. We found that under the experimental conditions the opening in the velarium assumed three distinct shapes during a swim contraction. The opening was (1) centred or it was off-centred and pocketed out either towards (2) a rhopalium or (3) a pedalium. The shape of the opening in the velarium followed the direction of the stimulus as long as the stimulus contained directional information. When the stimulus contained no directional information, the percentage of centred pulses increased and the shape of the off-centred pulses had a random orientation. Removing one rhopalium did not change the directional response of the animals, however, the number of centred pulses increased. When three rhopalia were removed, the percentage of centred pulses increased even further and the animals lost their ability to respond to directional information.
Does the magnocellular octaval nucleus process auditory information in the toadfish, Opsanus tau?
Venue: Journal of Comparative Physiology A

Previous work on auditory processing in Opsanus tau has focused on the descending octaval nucleus; however, the magnocellular octaval nucleus receives similar inputs from the otolithic endorgans. The purpose of this study was to assess whether cells in any of the three subdivisions of the magnocellular nucleus respond to auditory frequencies and encode sound source direction. Extracellular recording sites were chosen based on anatomical landmarks, and neurobiotin injections confirmed the location of auditory sites in subdivisions of the magnocellular nucleus. In general, the auditory cells in M2 and M3 responded best to frequencies at or below 100 Hz. Most auditory cells responded well to directional stimuli presented along axes in the horizontal plane. Cells in M3 (not M2) also responded to lateral line stimulation, consistent with otolithic endorgan and lateral line inputs to M3. The convergence of auditory and lateral line inputs in M3, the lack of Mauthner cells in this species, and previous evidence that the magnocellular nucleus does not contribute to ascending auditory pathways suggest to us that the large cells of M3 may play a role in rapid behavioral responses to particle motion stimuli in oyster toadfish.
Neurons innervating the lamina in the butterfly, Papilio xuthus
Venue: Journal of Comparative Physiology A

The butterfly Papilio xuthus has compound eyes with three types of ommatidia. Each type houses nine spectrally heterogeneous photoreceptors (R1–R9) that are divided into six spectral classes: ultraviolet, violet, blue, green, red, and broad-band. Analysis of color discrimination has shown that P. xuthus uses the ultraviolet, blue, green, and red receptors for foraging. The ultraviolet and blue receptors are long visual fibers terminating in the medulla, whereas the green and red receptors are short visual fibers terminating in the lamina. This suggests that processing of wavelength information begins in the lamina in P. xuthus, unlike in flies. To establish the anatomical basis of color discrimination mechanisms, we examined neurons innervating the lamina by injecting Neurobiotin into this neuropil. We found that in addition to photoreceptors and lamina monopolar cells, three distinct groups of cells project fibers into the lamina. Their cell bodies are located (1) at the anterior rim of the medulla, (2) between the proximal surface of the medulla and lobula plate, and (3) in the medulla cell body rind. Neurobiotin injection also labeled distinct terminals in medulla layers 1, 2, 3, 4 and 5. Terminals in layer 4 belong to the long visual fibers (R1, 2 and 9), while arbors in layers 1, 2 and 3 probably correspond to terminals of three subtypes of lamina monopolar cells, respectively. Immunocytochemistry coupled with Neurobiotin injection revealed their transmitter candidates; neurons in (1) and a subset of neurons in (2) are immunoreactive to anti-serotonin and anti-γ-aminobutyric acid, respectively.