nils-herrmann/clean_scirepeval huggingface dataset:
Post-metamorphic carry-over effects of altered thyroid hormone level and developmental temperature: physiological plasticity and body condition at two life stages in Rana temporaria
Venue: Journal of Comparative Physiology B

Environmental stress induced by natural and anthropogenic processes including climate change may threaten the productivity of species and persistence of populations. Ectotherms can potentially cope with stressful conditions such as extremes in temperature by exhibiting physiological plasticity. Amphibian larvae experiencing stressful environments display altered thyroid hormone (TH) status with potential implications for physiological traits and acclimation capacity. We investigated how developmental temperature (Tdev) and altered TH levels (simulating proximate effects of environmental stress) influence the standard metabolic rate (SMR), body condition (BC), and thermal tolerance in metamorphic and post-metamorphic anuran larvae of the common frog (Rana temporaria) reared at five constant temperatures (14–28 °C). At metamorphosis, larvae that developed at higher temperatures had higher maximum thermal limits but narrower ranges in thermal tolerance. Mean CTmax was 37.63 °C ± 0.14 (low TH), 36.49 °C ± 0.31 (control), and 36.43 °C ± 0.68 (high TH) in larvae acclimated to different temperatures. Larvae were able to acclimate to higher Tdev by adjusting their thermal tolerance, but not their SMR, and this effect was not impaired by altered TH levels. BC was reduced by 80% (metamorphic) and by 85% (post-metamorphic) at highest Tdev. The effect of stressful larval conditions (i.e., different developmental temperatures and, to some extent, altered TH levels) on SMR and particularly on BC at the onset of metamorphosis was carried over to froglets at the end of metamorphic climax. This has far reaching consequences, since body condition at metamorphosis is known to determine metamorphic success and, thus, is indirectly linked to individual fitness in later life stages.
Sound localization in barn owls studied with manipulated head-related transfer functions: beyond broadband interaural time and level differences
Venue: Journal of Comparative Physiology A

Interaural time and level differences are important cues for sound localization. We wondered whether the broadband information contained in these two cues could fully explain the behavior of barn owls and responses of midbrain neurons in these birds. To tackle this problem, we developed a novel approach based on head-related transfer functions. These filters contain the complete information present at the eardrum. We selected positions in space characterized by equal broadband interaural time and level differences. Stimulation from such positions provides reduced information to the owl. We show that barn owls are able to discriminate between such positions. In many cases, but not all, the owls may have used spectral components of interaural level differences that exceeded the known behavioral resolution and variability for discrimination. Alternatively, the birds may have used template matching. Likewise, neurons in the optic tectum of the barn owl, a nucleus involved in sensorimotor integration, contained more information than is available in the broadband interaural time and level differences. Thus, these data show that more information is available and used by barn owls for sound localization than carried by broadband interaural time and level differences.
Effects of feed restriction on growth performance, lipid mobilization, and gene expression in rose spotted snapper (Lutjanus guttatus)
Venue: Journal of Comparative Physiology B

The effects of feed deprivation were evaluated for 1 week and 2 weeks in Lutjanus guttatus juveniles. A significant reduction in body mass was observed in both feed deprivation schemes, as well as in hepatosomatic, viscerosomatic and mesenteric fat indexes. The composition of fasted fish was characterized by a decrease in lipid content; the liver displayed an intense reduction of lipid reserves in both fasted groups, and increased expression of the lysosomal acid lipase. 1 week after re-feeding, both experimental groups showed an increase in specific growth rate, feed intake and feed conversion ratio. A recovery in hepatic lipid reserves was observed, and the expression of the lysosomal acid lipase decreased, although lipid content in both groups was still significantly lower than in control groups. Hepatic expression of the growth hormone receptor decreased after fasting, and remained low even after the fish were fed, whereas the expression of insulin-like growth factor 1 and 2 increased after fasting and decreased in both groups when fish were fed again. Altogether, these results showed a partial compensatory growth response in L. guttatus juveniles after fasting, with enhanced growth rates and improved feed efficiency. Fish used stored lipid reserves as the main energy source, and the expression of growth-related and lipid mobilization marker genes in the liver showed similar patterns in both fasting schemes. Based on the results, we suggest as much as 1-week fasting intervals during grow-out programmes to reduce visceral fat and increase growth rate in this species.
Comparative energetics and thermal responses to feeding in allied Agkistrodon snakes with contrasting diet and habitat use
Venue: Journal of Comparative Physiology B

Variation in animal responses to feeding can be attributed to a variety of ecological factors, including foraging mode and dietary specialization. Specialization often favors species that have traits for exploiting food resources that are rare and that are not commonly shared by dietary generalists. We investigated physiological and behavioral responses to feeding between two snake species with different degrees of mammal feeding specialization: Agkistrodon contortrix (copperheads; a terrestrial species in which adults feed almost exclusively on mammals) and Agkistrodon piscivorus (cottonmouths; a semi-aquatic species feeding less on mammals and primarily on ectothermic prey). We measured metabolic rates (at 20, 25, and 30 °C) and body temperature (Tb) selection of snakes both pre- and post-feeding. Following the consumption of rodent meals, post-feeding energy use was higher in A. piscivorus than A. contortrix at both 25 and 30 °C. After feeding, A. piscivorus maintained body temperatures that were 3–4 °C higher, whereas A. contortrix remained within 1 °C of their pre-feeding Tb. Our results support the contention that dietary specialization leads to potential energetic advantages and that generalist species may change their behavior to offset energy used to digest prey.
Ontogeny of electric organ and electric organ discharge in Campylomormyrus rhynchophorus (Teleostei: Mormyridae)
Venue: Journal of Comparative Physiology A

The aim of this study was a longitudinal description of the ontogeny of the adult electric organ of Campylomormyrus rhynchophorus which produces as adult an electric organ discharge of very long duration (ca. 25 ms). We could indeed show (for the first time in a mormyrid fish) that the electric organ discharge which is first produced early during ontogeny in 33-mm-long juveniles is much shorter in duration and has a different shape than the electric organ discharge in 15-cm-long adults. The change from this juvenile electric organ discharges into the adult electric organ discharge takes at least a year. The increase in electric organ discharge duration could be causally linked to the development of surface evaginations, papillae, at the rostral face of the electrocyte which are recognizable for the first time in 65-mm-long juveniles and are most prominent at the periphery of the electrocyte.
Puncture versus capture: which stresses animals the most?
Venue: Journal of Comparative Physiology B

The prerogative of animal welfare science includes wild species and ecological studies. Yet, guidance enshrined in legislation is narrowly derived from studies involving laboratory rodents; legitimacy for non-mammalian free-ranging species is thus debatable. The European directive 2010/63/EU illustrates this problem. It includes this key statement: “Practices not likely to cause pain, suffering, distress or lasting harm equivalent to, or higher than, that caused by the introduction of a needle…” which determines if the directive shall apply. Protocols involving surgery clearly fall within the scope of the directive: procedures are scrutinized, investigators and technicians must be qualified and various agreements are required (e.g. issued by an ethical committee). By contrast, non-invasive procedures, like mark-recapture population studies, merely need a permit from wildlife authorities (at least in most countries). Yet, blood sampling that implies the introduction of a needle—one of the most common practices in animals—could shift any study on the constraining-side of the directive, on the grounds that puncture impacts individuals more severely than capture. We examined the validity of the needle-threshold using the stress response of free-ranging snakes. Our results based on physiological markers show that blood sampling does not add any stress to that triggered by capture, and thus questions the usefulness of the needle-threshold to gauge welfare in wild animals. The specificities of studying wild species should be considered to redress captivity biased animal welfare policy.
Age differences in night-time metabolic rate and body temperature in a small passerine
Venue: Journal of Comparative Physiology B

Spending the winter in northern climes with short days and cold ambient temperatures ( T a ) can be energetically challenging for small birds that have high metabolic and heat loss rates. Hence, maintaining body temperature ( T b ) in T a below thermoneutrality can be energetically costly for a small bird. We still know little about how increased heat production below thermoneutrality affects the level at which T b is maintained, and if these patterns are age specific. To test this, we measured subcutaneous body temperature ( T s ) and resting metabolic rate (RMR) simultaneously in blue tits ( Cyanistes caeruleus ) during winter nights in T a ’s ranging from 25 to − 15 °C. RMR increased below the lower critical temperature (LCT, estimated at 14 °C) and was 6% higher in young (birds in their first winter) compared to old birds (birds in their second winter or older). The higher RMR was also mirrored in higher T s and thermal conductance ( C ) in young birds, which we suggest could be caused by age differences in plumage quality, likely driven by time constraints during moult. Reduction in nightly predicted T b was modest and increased again at the coldest ambient temperatures, suggesting that either heat retention or heat production (or both) improved when T a reached levels which are cold by the standards of birds in our population. Our results show that levels of heat production and T b can be age specific. Further studies should address age-specific differences on quality, structure, and thermal conductivity of plumage more explicitly, to investigate the role of variation in insulation in age-linked metabolic phenotypes.
Binocular responsiveness of projection neurons of the praying mantis optic lobe in the frontal visual field
Venue: Journal of Comparative Physiology A

Praying mantids are the only insects proven to have stereoscopic vision (stereopsis): the ability to perceive depth from the slightly shifted images seen by the two eyes. Recently, the first neurons likely to be involved in mantis stereopsis were described and a speculative neuronal circuit suggested. Here we further investigate classes of neurons in the lobula complex of the praying mantis brain and their tuning to stereoscopically-defined depth. We used sharp electrode recordings with tracer injections to identify visual projection neurons with input in the optic lobe and output in the central brain. In order to measure binocular response fields of the cells the animals watched a vertical bar stimulus in a 3D insect cinema during recordings. We describe the binocular tuning of 19 neurons projecting from the lobula complex and the medulla to central brain areas. The majority of neurons (12/19) were binocular and had receptive fields for both eyes that overlapped in the frontal region. Thus, these neurons could be involved in mantis stereopsis. We also find that neurons preferring different contrast polarity (bright vs dark) tend to be segregated in the mantis lobula complex, reminiscent of the segregation for small targets and widefield motion in mantids and other insects.
Residual vitellus and energetic state of wolf spiderlings Pardosa saltans after emergence from egg-sac until first predation
Venue: Journal of Comparative Physiology B

The aim of this study was to evaluate energetic source used by juveniles of a terrestrial oviparous invertebrate during the earliest periods of their life. Growth, behavioural activities and energy contents of Pardosa saltans spiderlings’ residual vitellus were monitored during 8 days after their emergence from their egg-sac until they disperse autonomously. The life-cycle of juvenile after emergence can be divided into three periods: a gregarious while juveniles are aggregated on their mother, dismounting off their mother’s back and dispersion. We present the first biochemical study of residual vitellus and energy expenditure during these three periods. At emergence, the mean weight of juveniles was 0.59 mg and energy stock from residual vitellus averaged 51 cal/g wet mass. During gregarious period, the weight of the juveniles aggregated on their mother did not vary significantly and juveniles utilized only 1 cal/day from their residual vitellus. During the period from dismounting until their first exogenous feed, juveniles lost weight and used 30% of their residual vitellus stock. Proteins from the residual vitellus contributed principally to their energy expenditure during this period: 1.5 µg protein/day. Juveniles’ first exogenous feeding was observed 7–8 days after emergence, when 70% of residual vitellus energy had been utilized. Juveniles dispersed after eating, reconstituting an energy stock comparable to that observed at emergence from egg-sac (50 cal/g wet mass). This new energy stock contains mainly lipids unlike the energy stock from the residual vitellus.
Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal
Venue: Journal of Comparative Physiology A

Whisker touch is an active sensory system. Previous studies in Pinnipeds have adopted relatively stationary tasks to judge tactile sensitivity, which may not accurately promote natural whisker movements and behaviours. This study developed a novel feeding task, termed fish sweeping to encourage whisker movements. Head and whisker movements were tracked from video footage in Harbor seal ( Phoca vitulina ), California sea lion ( Zalophus californianus ) and Pacific walrus ( Odobenus rosmarus divergens ). All species oriented their head towards the moving fish target and moved their whiskers during the task. Some species also engaged in whisker control behaviours, including head-turning asymmetry in the Pacific walrus, and contact-induced asymmetry in the Pacific walrus and California sea lion: behaviours that have only previously been observed in terrestrial mammals. This study confirms that Pinnipeds should be thought of as whisker specialists, and that whisker control (movement and positioning) is an important aspect of touch sensing in these animals, especially in sea lions and walruses. That the California sea lion controls whisker movement in relation to an object, and also had large values of whisker amplitude, spread and asymmetry, suggests that California sea lions are a promising model with which to further explore active touch sensing.
Ontogenetic expression rhythms of visual opsins in senegalese sole are modulated by photoperiod and light spectrum
Venue: Journal of Comparative Physiology B

In the fish retina, rods and cones are responsible for nocturnal vision and colour perception, respectively, and exhibit a repertoire of light-sensitive opsin photopigments that permits the adaptation to different photic environment. The metamorphosis of Senegalese sole determines a migration from pelagic to benthic environments, which is accompanied by essential changes in light intensity and spectrum. In this paper, we analysed the daily expression rhythms of rod opsin and five cone opsins during sole ontogeny in animals maintained under light–dark cycles of white (LDW), blue (LDB), red (LDR) and continuous white (LL) lights. We showed that the expression of visual opsins at early stages of development was enhanced under LDB in relation to LDW, LDR and LL. Moreover, daily rhythms of opsins were more robust under LDW and LDB conditions, in particular, before and after metamorphosis. A shift in the phase of opsin rhythms was observed between hatching and pre-metamorphosis. Metamorphosis was accompanied by a transient loss in the expression rhythms for most of the opsins, which were significantly influenced by light photoperiod and spectrum. In LDR, transcript levels and rhythms were markedly affected for the majority of the opsins analysed. Under LL, most of the opsins examined exhibited endogenous rhythms, although amplitudes and acrophases changed considerably. To the best of our knowledge, this is the first study on the daily expression rhythms of visual opsins during the ontogeny of a metamorphic flatfish and further emphasises the importance of using natural lighting conditions for proper development of Senegalese sole.
Functional organization of the primary auditory cortex of the free-tailed bat Tadarida brasiliensis
Venue: Journal of Comparative Physiology A

The Mexican free-tailed bat, Tadarida brasiliensis, is a fast-flying bat that hunts by biosonar at high altitudes in open space. The auditory periphery and ascending auditory pathways have been described in great detail for this species, but nothing is yet known about its auditory cortex. Here we describe the topographical organization of response properties in the primary auditory cortex (AC) of the Mexican free-tailed bat with emphasis on the sensitivity for FM sweeps and echo-delay tuning. Responses of 716 units to pure tones and of 373 units to FM sweeps and FM–FM pairs were recorded extracellularly using multielectrode arrays in anesthetized bats. A general tonotopy was confirmed with low frequencies represented caudally and high frequencies represented rostrally. Characteristic frequencies (CF) ranged from 15 to 70 kHz, and fifty percent of CFs fell between 20 and 30 kHz, reflecting a hyper-representation of a bandwidth corresponding to search-phase echolocation pulses. Most units showed a stronger response to downward rather than upward FM sweeps and forty percent of the neurons interspersed throughout AC (150/371) showed echo-delay sensitivity to FM–FM pairs. Overall, the results illustrate that the free-tailed bat auditory cortex is organized similarly to that of other FM-type insectivorous bats.
Vitamin A: its many roles—from vision and synaptic plasticity to infant mortality
Venue: Journal of Comparative Physiology A

The recognition that a dietary factor is essential to maintain good and sensitive vision as well as overall health goes back over 3,000 years to the ancient Egyptians. With the discovery of the vitamins at the turn of the twentieth century, fat-soluble vitamin A was soon shown to be the essential factor. In the first half of the twentieth century, the role vitamin A plays in vision, as precursor to the light-sensitive visual pigment molecules in the photoreceptors was elegantly worked out, especially by George Wald and his colleagues. Beginning in the 1960s, with the recognition of the active metabolite of vitamin A, its acid form now called retinoic acid, the roles of vitamin A in maintaining overall health of an organism began to be explored, and this research continues to this day. Receptors activated by retinoic acid, the RARs and RXRs have been shown to regulate gene transcription in a surprisingly wide variety of biological processes from early growth and development to the maintenance of epithelial tissues in many organs, the regulation of the immune system, and even the modulation of synaptic function in the brain involved in mechanisms underlying memory and learning. Therapeutic uses for retinoic acid have been developed, including one for a specific form of leukemia. The story is by no means complete and it is likely more surprises await with regard to this remarkable molecule.
White mouse pups can use torpor for energy conservation
Venue: Journal of Comparative Physiology B

White mice are ubiquitous laboratory animals and have been extensively studied. To reveal potential undiscovered traits, we tested the hypothesis that during development, when heat loss in mouse pups is high, they can use daily torpor for energy conservation. We determined at what age individual mouse pups are able to defend their body temperature at room temperature (ambient temperature, T a  = 20 °C) and whether they could use torpor from that time. Initially at 5/6 days (body mass, BM ~ 3 g), still naked mice cooled rapidly. In contrast, at ~ 14 days (BM ~ 6 g), they could maintain a high, constant body temperature and, therefore, had reached competent endothermy. These mouse pups at ~ 20% of adult BM were able to enter into and arouse from torpor as determined via the rate of oxygen consumption; this was the case for both individuals that were exposed to a cooling regime as well as those that were not. During torpor, metabolism fell by up to > 90% and torpor lasted for up to 12 h. As mice grew, torpor was still used but was less pronounced. Our study shows that although the physiology of laboratory mice has been widely examined, their functional capabilities have still not been fully revealed, which has implications for biomedicine. Our and other developmental data suggest that because torpor is so efficient in conserving energy, it is likely to be used during the growth phase by diverse mammals and birds to survive energetic and thermal challenges.
Path integration in a three-dimensional world: the case of desert ants
Venue: Journal of Comparative Physiology A

Desert ants use path integration to return from foraging excursions on a shortcut way to their nests. Intriguingly, when walking over hills, the ants incorporate the ground distance, the paths’ projection to the horizontal plane, into their path integrator. This review discusses how Cataglyphis may solve this computational feat. To infer ground distance, ants must incorporate the inclination of path segments into the assessment of distance. Hair fields between various joints have been eliminated as likely sensors for slope measurement, without affecting slope detection; nor do postural adaptations or changes in gait provide the relevant information. Changes in the sky’s polarization pattern due to different head inclinations on slopes were ruled out as cues. Thus, the mechanisms by which ants may measure slopes still await clarification. Remarkably, the precision of slope measurement is roughly constant up to a 45° inclination, but breaks down at 60°. An encounter of sloped path segments during a foraging trip induces a general acceptance of slopes, however, slopes are not associated with specific values of the home vector. All current evidence suggests that Cataglyphis does not compute a vector in 3-D: path integration seems to operate exclusively in the horizontal plane.