nils-herrmann/clean_scirepeval huggingface dataset:
Cardiovascular resistance to thrombosis in 13-lined ground squirrels
Venue: Journal of Comparative Physiology B

Abstract13-lined ground squirrels (Ictidomys tridecemlineatus) enter hibernation as a survival strategy during extreme environmental conditions. Typical ground squirrel hibernation is characterized by prolonged periods of torpor with significantly reduced heart rate, blood pressure, and blood flow, interrupted every few weeks by brief interbout arousals (IBA) during which blood flow fluctuates dramatically. These physiological conditions should increase the risk of stasis-induced blood clots and myocardial ischemia. However, ground squirrels have adapted to survive repeated bouts of torpor and IBA without forming lethal blood clots or sustaining lethal ischemic myocardial damage. The purpose of this study was to determine if ground squirrels are resistant to thrombosis and myocardial ischemia during hibernation. Blood markers of coagulation, fibrinolysis, thrombosis, and ischemia, as well as histological markers of myocardial ischemia were measured throughout the annual hibernation cycle. Hibernating ground squirrels were also treated with isoprenaline to induce myocardial ischemia. Thrombin–antithrombin complex levels were significantly reduced (p < 0.05) during hibernation, while D-dimer level remained unchanged throughout the annual cycle, both consistent with an antithrombotic state. During torpor, the ground squirrels were in a hyperfibrinolytic state with an elevated ratio of tissue plasminogen activator complexed with plasminogen activator inhibitor to total plasminogen activator inhibitor (p < 0.05). Histological markers of myocardial ischemia were reversibly elevated during hibernation with no increase in markers of myocardial cell death in the blood. These data suggest that ground squirrels do not form major blood clots during hibernation through suppression of coagulation and a hyperfibrinolytic state. These animals also demonstrate myocardial resistance to ischemia.
The similarity of crawling mechanisms in aquatic and terrestrial gastropods
Venue: Journal of Comparative Physiology A

Crawling gastropods are unique models for studying the functioning of smooth muscles and ciliated epithelia, since they cover the foot sole and are involved in locomotion, allowing for direct investigation. Two types of crawling are known: creeping by muscular waves in terrestrial gastropods such as Helix and сiliary gliding in aquatic gastropods such as Lymnaea. It was found that the smooth muscles that underlie the ciliated epithelium in Lymnaea are involved in gliding and contribute significantly to fast crawling. Thus, the locomotor apparatus is fundamentally the same in both snails and the difference between crawling reflects an adaptation to a habitat. The control of crawling speed is also the same. Tonic contraction, relaxation, and rhythmic contractions are involved in this control. During a locomotor episode, the sole length and crawling speed spontaneously change and directly correlate with each other via the contraction force of the muscle cells in the locomotory waves. Dopamine, unlike ergometrine, decreases the sole length and crawling speed. Serotonin stimulates, increases crawling and determines the number of muscle cells involved in the locomotory waves for each locomotor episode. This control (taking into account heterogeneity) apparently might exist in any other phasic smooth muscle, including vertebrates.
A simple mathematical model using centred loops and random perturbations accurately reconstructs search patterns observed in desert ants
Venue: Journal of Comparative Physiology A

This paper describes a new mathematical model that is based on centred loops to reconstruct the “Systematic Search” behaviour of Cataglyphis desert ants. The notable advantage of this model is the combination of simplicity, efficiency and performance. All model input is kept to a minimum, using only parameters that previous research has shown to be available to the animals at all times: distance from the origin, direction of the last step and home vector. Outbound and inbound search paths are being combined into loops that return to the origin, sampling this area more intensely. A stochastic element is added by random perturbations during the next step, mimicking unsystematic errors during the process of path integration and yielding the typical search patterns observed in Cataglyphis desert ants. The model output is compared to runs observed in the field.
Iridescent colouration of male Anna’s hummingbird (Calypte anna) caused by multilayered barbules
Venue: Journal of Comparative Physiology A

The male Anna’s hummingbird features a brightly reddish-pink reflecting gorget, due to large stacks of melanosomes in the feather barbules, arranged in layers separated by keratin. Direct observations together with detailed scatterometry demonstrated that the barbules reflect incident light in an approximately specular manner. The structural colouration is iridescent, i.e. varies with a changing angle of light incidence. Spectrophotometrical measurements of the barbule reflectance and absorbance can be well interpreted with calculated spectra obtained with a transfer matrix method for optical multilayers, using anatomical data and measured refractive index spectra. The organization of the reflectors as a Venetian blind presumably functions to create a high spectral contrast of the male’s plumage during courtship.
Effect of temperature on the locomotor performance of species in a lizard assemblage in the Puna region of Argentina
Venue: Journal of Comparative Physiology B

Locomotion is relevant to the ecology of reptiles because of its presumed influence on an organism’s Darwinian fitness. Moreover, in ectothermic species, physiological performance capacity is affected by body temperature. We analyzed two components of locomotor performance in three species of lizards, Phymaturus extrilidus, Liolaemus parvus, and Liolaemus ruibali, in the Puna environment of Argentina. First, we estimated the thermal sensitivity of locomotion by measuring sprint speed at four different body temperatures. We included two measures of sprint speed: initial velocity and long sprint for sustained runs. Based on these data, we calculated the optimal temperature for performance and the optimal performance breadth. We also estimated endurance capacity at a single temperature. Maximum sprint speed for L. parvus was greater than L. ruibali and P. extrilidus in both initial velocity and long sprint. In contrast, L. parvus exhibited lower levels of endurance than L. ruibali and P. extrilidus. However, endurance in L. ruibali exceeded that of P. extrilidus. The species differed in the optimal temperature for the initial velocity with the lowest for L. ruibali (31.8 °C) followed by P. extrilidus (33.25 °C) and then L. parvus (36.25 °C). The optimal temperature for long sprint varied between 32 and 36 °C for all species. We found that all species attained maximum performance at body temperatures commonly experienced during daily activity, which was higher than the thermal quality of the environment. We found evidence for thermal sensitivity in locomotor performance in these species. However, we also show that the broad thermal breadth of performance suggests that the lizards are capable of sustaining near optimal levels of locomotor performance at ambient temperatures that would appear to be suboptimal. Thus, this lizard assemblage is capable of coping with the highly variable climatic conditions in the Puna region of Argentina.
Hemodynamics of tonic immobility in the American alligator (Alligator mississippiensis) identified through Doppler ultrasonography
Venue: Journal of Comparative Physiology A

American alligators (Alligator mississippiensis) held inverted exhibit tonic immobility, combining unresponsiveness with flaccid paralysis. We hypothesize that inverting the alligator causes a gravitationally promoted increase in right aortic blood flowing through the foramen of Panizza, with a concurrent decrease in blood flow through the primary carotid, and thereby of cerebral perfusion. Inverting the alligator results in displacement of the liver, post-pulmonary septum, and the heart. EKG analysis revealed a significant decrease in heart rate following inversion; this decrease was maintained for approximately 45 s after inversion which is in general agreement with the total duration of tonic immobility in alligators (49 s). Doppler ultrasonography revealed that following inversion of the alligator, there was a reversal in direction of blood flow through the foramen of Panizza, and this blood flow had a significant increase in velocity (compared to the foraminal flow in the prone alligator). There was an associated significant decrease in the velocity of blood flow through the primary carotid artery once the alligator was held in the supine position. Tonic immobility in the alligator appears to be a form of vasovagal syncope which arises, in part, from the unique features of the crocodilian heart.
Independent processing of increments and decrements in odorant concentration by ON and OFF olfactory receptor neurons
Venue: Journal of Comparative Physiology A

A salient feature of the insect olfactory system is its ability to detect and interpret simultaneously the identity and concentration of an odorant signal along with the temporal stimulus cues that are essential for accurate odorant tracking. The olfactory system of the cockroach utilizes two parallel pathways for encoding of odorant identity and the moment-to-moment succession of odorant concentrations as well as the rate at which concentration changes. This separation originates at the peripheral level of the ORNs (olfactory receptor neurons) which are localized in basiconic and trichoid sensilla. The graded activity of ORNs in the basiconic sensilla provides the variable for the combinatorial representation of odorant identity. The antagonistically responding ON and OFF ORNs in the trichoid sensilla transmit information about concentration increments and decrements with excitatory signals. Each ON and OFF ORN adjusts its gain for odorant concentration and its rate of change to the temporal dynamics of the odorant signal: as the rate of change diminishes, both ORNs improve their sensitivity for the rate of change at the expense of the sensitivity for the instantaneous concentration. This suggests that the ON and OFF ORNs are optimized to detect minute fluctuations or even creeping changes in odorant concentration.
Effects of photoperiod, temperature and aging on adult diapause termination and post-diapause development in female Asian comma butterflies, Polygonia c-aureum Linnaeus (Lepidoptera: Nymphalidae)
Venue: Journal of Comparative Physiology A

Polygonia c-aureum females exhibit photoperiodically induced imaginal diapause, characterized by cessation of ovarian development. Females grown at a short daylength (SD) entered imaginal diapause, whereas those grown at a long daylength (LD) produced eggs rapidly after adult emergence at 21 °C. The termination of diapause was influenced by daylength: diapause ended faster at LD than SD. Complete termination of diapause took 30 days in unchilled females reared under LD at 21 °C. On the other hand, prompt, synchronized and strong diapause termination occurred at post-chilling periods. Photoperiods at post-chilling periods affected ovarian development, when the length of pre-chilling periods or the length of chilling periods was shorter, suggesting that these treatments were not enough to complete diapause development. Ovarian development proceeded earlier in chilled and subsequent warmed females than unchilled females. Wing damage was remarkable at post-chilling periods when females were reared under an adequate length of pre-chilling and chilling periods, especially comparing with females under pre-overwintering conditions without chilling, indicating that post-diapause reproductive development was weak in unchilled females. Thus, exposure to low temperatures is necessary for a strong diapause termination in this butterfly.
Flutter sensitivity in FM bats. Part I: delay modulation
Venue: Journal of Comparative Physiology A

Echolocating bats measure target distance by the time delay between call and echo. Target movement such as the flutter of insect wings induces delay modulations. Perception of delay modulations has been studied extensively in bats, but only concerning how well bats discriminate flutter frequencies, never with regard to flutter magnitude. We used an auditory virtual reality approach to generate changes in echo delay that were independent of call repetition rate, mimicking fluttering insect wings. We show that in the frequency-modulating (FM) bat Phyllostomus discolor, the sensitivity for modulations in echo delay depends on the rate of the modulation, with bats being most sensitive at modulation rates below 20 Hz and above 50 Hz. The very short duration of their calls compels FM bats to evaluate slow modulations (< about 100 Hz) across entire echo sequences. This makes them susceptible to interference between their own call repetition rate and the modulation rate. We propose that this phenomenon constitutes an echo-acoustic wagon-wheel effect. We further demonstrate how at high modulation rates, flutter sensitivity could be rescued by using spectral and temporal cues introduced by Doppler distortions. Thus, Doppler distortions may play a crucial role in flutter sensitivity in the hundreds of FM species worldwide.
Flutter sensitivity in FM bats. Part II: amplitude modulation
Venue: Journal of Comparative Physiology A

Bats use echolocation to detect targets such as insect prey. The echolocation call of frequency-modulating bats (FM bats) typically sweeps through a broad range of frequencies within a few milliseconds. The large bandwidth grants the bat high spatial acuity in depicting the target. However, the extremely short call duration and the overall low duty cycle of call emission impair the bat’s capability to detect e.g. target movement. Nonetheless, FM bats constitute more than 80% of all echolocating species and are able to navigate and forage in an environment full of moving targets. We used an auditory virtual reality approach to generate changes in echo amplitude reflective of fluttering insect wings independently from other confounding parameters. We show that the FM bat Phyllostomus discolor successfully detected these modulations in echo amplitude and that their performance increased with the rate of the modulation, mimicking faster insect wing-beats. The ability of FM bats to detect amplitude modulations of echoes suggests a release from the trade-off between spatial and temporal acuity and highlights the diversity of selective pressures working on the echolocation system of bats.
Changes in electrophysiological properties of photoreceptors in Periplaneta americana associated with the loss of screening pigment
Venue: Journal of Comparative Physiology A

Absence of screening pigment in insect compound eyes has been linked to visual dysfunction. We investigated how its loss in a white-eyed mutant (W-E) alters the photoreceptor electrophysiological properties, opsin gene expression, and the behavior of the cockroach, Periplaneta americana. Whole-cell patch-clamp recordings of green-sensitive photoreceptors in W-E cockroaches gave reduced membrane capacitance, absolute sensitivity to light, and light-induced currents. Decreased low-pass filtering increased voltage-bump amplitudes in W-E photoreceptors. Intracellular recordings showed that angular sensitivity of W-E photoreceptors had two distinct components: a large narrow component with the same acceptance angle as wild type, plus a relatively small wide component. Information processing was evaluated using Gaussian white-noise modulated light stimulation. In bright light, W-E photoreceptors demonstrated higher signal gain and signal power than wild-type photoreceptors. Expression levels of the primary UV- and green-sensitive opsins were lower and the secondary green-sensitive opsin significantly higher in W-E than in wild-type retinae. In behavioral experiments, W-E cockroaches were significantly less active in dim green light, consistent with the relatively low light sensitivity of their photoreceptors. Overall, these differences can be related to the loss of screening pigment function and to a compensatory decrease in the rhabdomere size in W-E retinae.
Auditory-vocal coupling in the naked mole-rat, a mammal with poor auditory thresholds
Venue: Journal of Comparative Physiology A

Naked mole-rats are extremely social and extremely vocal rodents, displaying a wide range of functionally distinct call types and vocalizing almost continuously. Their vocalizations are low frequency, and a behavioral audiogram has shown that naked mole-rats, like other subterranean mammals, hear only low frequencies. Hence, the frequency range of their hearing and vocalizations appears to be well matched. However, even at low frequencies, naked mole-rats show very poor auditory thresholds, suggesting vocal communication may be effective only over short distances. However, in a tunnel environment where low frequency sounds propagate well and background noise is low, it may be that vocalizations travel considerable distances at suprathreshold intensities. Here, we confirmed hearing sensitivity using the auditory brainstem response; we characterized signature and alarm calls in intensity and frequency domains and we measured the effects of propagation through tubes with the diameter of naked mole-rat tunnels. Signature calls—used for intimate communication—could travel 3–8 m at suprathreshold intensities, and alarm calls (lower frequency and higher intensity), could travel up to 15 m. Despite this species’ poor hearing sensitivity, the naked mole-rat displays a functional, coupled auditory-vocal communication system—a hallmark principle of acoustic communication systems across taxa.
Ameliorating the adverse cardiorespiratory effects of chemical immobilization by inducing general anaesthesia in sheep and goats: implications for physiological studies of large wild mammals
Venue: Journal of Comparative Physiology B

Chemical immobilization is necessary for the physiological study of large wild animals. However, the immobilizing drugs can adversely affect the cardiovascular and respiratory systems, yielding data that do not accurately represent the normal, resting state. We hypothesize that these adverse effects can be ameliorated by reversing the immobilizing agent while holding the animal under general anaesthesia. We used habituated sheep Ovis aries (N = 5, 46.9 ± 5.3 kg body mass, mean ± SEM) and goats Capra hircus (N = 4, 27.7 ± 2.8 kg) as ungulate models for large wild animals, and measured their cardiorespiratory function under three conditions: (1) mild sedation (midazolam), as a proxy for the normal resting state, (2) immobilization (etorphine and azaperone), and (3) general anaesthesia (propofol) followed by etorphine antagonism (naltrexone). Cardiac output for both sheep and goats remained unchanged across the three conditions (overall means of 6.2 ± 0.9 and 3.3 ± 0.3 L min−1, respectively). For both sheep and goats, systemic and pulmonary mean arterial pressures were significantly altered from initial midazolam levels when administered etorphine + azaperone, but those arterial pressures were restored upon transition to propofol anaesthesia and antagonism of the etorphine. Under etorphine + azaperone, minute ventilation decreased in the sheep, though this decrease was corrected under propofol, while the minute ventilation in the goats remained unchanged throughout. Under etorphine + azaperone, both sheep and goats displayed arterial blood hypoxia and hypercapnia (relative to midazolam levels), which failed to completely recover under propofol, indicating that more time might be needed for the blood gases to be adequately restored. Nonetheless, many of the confounding cardiorespiratory effects of etorphine were ameliorated when it was antagonized with naltrexone while the animal was held under propofol, indicating that this procedure can largely restore the cardiovascular and respiratory systems closer to a normal, resting state.
Response of rainbow trout’s (Oncorhynchus mykiss) hypothalamus to glucose and oleate assessed through transcription factors BSX, ChREBP, CREB, and FoxO1
Venue: Journal of Comparative Physiology A

We aimed to obtain information regarding mechanisms that link glucose- and fatty acid-sensing systems to expression of neuropeptides that regulate food intake in the fish brain. We assessed the relative expression and protein levels of the transcription factors BSX, ChREBP, FoxO1, and CREB in the hypothalamus of rainbow trout (Oncorhynchus mykiss) treated for 6 h with either glucose or oleate in vivo (intra-cerebroventricular treatment with 1 µl 100 g− 1 body weight of 40 µg glucose or 1 µmol oleate) or in vitro (incubation with 4–8 mM glucose or 100–500 µM oleate). BSX levels decreased after oleate treatment for mRNA (10% in vitro and 47% in vivo) and protein (25%), while minor changes occurred after glucose treatment. CREB values generally decreased after glucose or oleate treatment for mRNA (50% in vivo) as well as the phosphorylation status of protein (80%). Foxo1 mRNA levels increased in vivo with glucose (129%) and decreased in vivo with oleate (60%), and protein phosphorylation status increased with glucose (in vivo) and oleate. mRNA values of chrebpα decreased in response to glucose and oleate, while protein levels decreased with oleate and increased with glucose. The results support the association of several transcription factors with metabolic control of food intake in fish.
Evolutionarily conserved coding properties favour the neuronal representation of heterospecific signals of a sympatric katydid species
Venue: Journal of Comparative Physiology A

To function as a mechanism in premating isolation, the divergent and species-specific calling songs of acoustic insects must be reliably processed by the afferent auditory pathway of receivers. Here, we analysed the responses of interneurons in a katydid species that uses long-lasting acoustic trills and compared these with previously reported data for homologous interneurons of a sympatric species that uses short chirps as acoustic signals. Some interneurons of the trilling species respond exclusively to the heterospecific chirp due to selective, low-frequency tuning and “novelty detection”. These properties have been considered as evolutionary adaptations in the sensory system of the chirper, which allow it to detect signals effectively during the simultaneous calling of the sympatric sibling species. We propose that these two mechanisms, shared by the interneurons of both species, did not evolve in the chirper to guarantee its ability to detect the chirp under masking conditions. Instead we suggest that chirpers evolved an additional, 2-kHz component in their song and exploited pre-existing neuronal properties for detecting their song under masking noise. The failure of some interneurons to respond to the conspecific song in trillers does not prevent intraspecific communication, as other interneurons respond to the trill.