nils-herrmann/clean_scirepeval huggingface dataset:
Leg loss decreases endurance and increases oxygen consumption during locomotion in harvestmen.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Animal movements are highly constrained by morphology and energetics. In addition, predictable bodily damage can constrain locomotion even further. For example, for animals moving on land, losing legs may impose additional costs. We tested if losing legs affects the distance travelled over time (endurance) and the metabolic costs of locomotion (oxygen consumption) in Nelima paessleri harvestmen. These arachnids voluntary releases legs (i.e., autotomy) in response to predation attempts. We used flow-through respirometry as animals moved on a treadmill inside a sealed chamber. We found that endurance decreased gradually with an increasing number of legs lost. Interestingly, oxygen consumption increased only for harvestmen that lost three legs, but not for individuals that lost only a single leg. These results have different ecological and evolutionary implications. Reduced endurance may impair an animal's ability to continue moving away from potential predators, while increased oxygen consumption makes movement costlier. Our findings suggest that individuals have a threshold number of legs that can be lost before experiencing measurable energetic consequences. Overall, our findings illustrate how animals respond to morphological modifications (i.e., damage) that affect the physiology of locomotion.
Differential effects of bicarbonate on severe hypoxia- and hypercapnia-induced cardiac malfunctions in diverse fish species
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

We tested in six fish species [Pacific lamprey ( Lampetra richardsoni ), Pacific spiny dogfish ( Squalus suckleyi ), Asian swamp eel ( Monopterus albus ), white sturgeon ( Acipenser transmontanus ), zebrafish ( Danio rerio ), and starry flounder ( Platichthys stellatus )] the hypothesis that elevated extracellular [HCO 3 − ] protects spontaneous heart rate and cardiac force development from the known impairments that severe hypoxia and hypercapnic acidosis can induce. Hearts were exposed in vitro to either severe hypoxia (~ 3% of air saturation), or severe hypercapnic acidosis (either 7.5% CO 2 or 15% CO 2 ), which reduced heart rate (in six test species) and net force development (in three test species). During hypoxia, heart rate was restored by [HCO 3 − ] in a dose-dependent fashion in lamprey, dogfish and eel (EC 50  = 5, 25 and 30 mM, respectively), but not in sturgeon, zebrafish or flounder. During hypercapnia, elevated [HCO 3 − ] completely restored heart rate in dogfish, eel and sturgeon (EC 50  = 5, 25 and 30 mM, respectively), had a partial effect in lamprey and zebrafish, and had no effect in flounder. Elevated [HCO 3 − ], however, had no significant effect on net force of electrically paced ventricular strips from dogfish, eel and flounder during hypoxia and hypercapnia. Only in lamprey hearts did a specific soluble adenylyl cyclase (sAC) inhibitor, KH7, block the HCO 3 − -mediated rescue of heart rate during both hypoxia and hypercapnia, and was the only species where we conclusively demonstrated sAC activity was involved in the protective effects of HCO 3 − on cardiac function. Our results suggest a common HCO 3 − -dependent, sAC-dependent transduction pathway for heart rate recovery exists in cyclostomes and a HCO 3 − -dependent, sAC-independent pathway exists in other fish species.
A spider in motion: facets of sensory guidance
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Spiders show a broad range of motions in addition to walking and running with their eight coordinated legs taking them towards their resources and away from danger. The usefulness of all these motions depends on the ability to control and adjust them to changing environmental conditions. A remarkable wealth of sensory receptors guarantees the necessary guidance. Many facets of such guidance have emerged from neuroethological research on the wandering spider Cupiennius salei and its allies, although sensori-motor control was not the main focus of this work. The present review may serve as a springboard for future studies aiming towards a more complete understanding of the spider’s control of its different types of motion. Among the topics shortly addressed are the involvement of lyriform slit sensilla in path integration, muscle reflexes in the walking legs, the monitoring of joint movement, the neuromuscular control of body raising, the generation of vibratory courtship signals, the sensory guidance of the jump to flying prey and the triggering of spiderling dispersal behavior. Finally, the interaction of sensors on different legs in oriented turning behavior and that of the sensory systems for substrate vibration and medium flow are addressed.
Detection of heliothine sex pheromone components in the Australian budworm moth, Helicoverpa punctigera: electrophysiology, neuroanatomy, and behavior.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

This study examined electrophysiological responses of the Australian budworm moth Helicoverpa punctigera, to heliothine sex pheromone components, via single sensillum recordings (SSR), and examined male neuroanatomy using confocal microscopy and 3D imaging tools. We found that male H. punctigera have three distinct regions of the macroglomerular complex (MGC) in the antennal lobe. Male antennae have only two functional types of sensilla trichoidea (A and C) and type A sensilla contain an olfactory sensory neuron (OSN) that responds to the major sex pheromone component (Z)-11-hexadecenal (Z11-16:Ald) with axons projecting to the cumulus of the macroglomerular complex (MGC) in the antennal lobe. Type C sensilla contained large-spiking receptor neurons which responded primarily to (Z)-9-tetradecenal (Z9-14:Ald) and to a lesser degree to (Z)-11-hexadecenol (Z11-16:OH). These were co-compartmentalized with small-spiking receptor neurons in type C sensilla which responded strongly to Z9-14:Ald and (Z)-9-hexadecenal (Z9-16:Ald), and to a lesser degree to (Z)-11-hexadecenyl acetate (Z11-16:OAc) and Z11-16:OH. Axons from the two co-localized neurons in Type C sensilla projected to the two small MGC units, the dorsomedial anterior and dorsomedial posterior, respectively. In wind tunnel assays, the addition of Z9-16:Ald to an otherwise attractive blend completely shut down male H. punctigera upwind flight.
Youth in the study of comparative physiology: insights from demography in the wild
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Of all the properties of individual animals of interest to comparative physiologists, age and stage of development are among the most consequential. In a natural population of any species, the survivorship curve is an important determinant of the relative abundances of ages and stages of development. Demography, thus, has significant implications for the study of comparative physiology. When Edward Deevey published his influential summary of survivorship in animal populations in the wild seven decades ago, he emphasized “serious deficiencies” because survivorship curves for natural populations at the time did not include data on the earliest life stages. Such data have accumulated over intervening years. We survey, for the first time, empirical knowledge of early-age survivorship in populations of most major animal groups in a state of nature. Despite wide variation, it is almost universally true that > 50% of newly born or hatched individuals die before the onset of sexual maturity, even in species commonly assumed to exhibit high early-age survivorship. These demographic facts are important considerations for studies in comparative and environmental physiology whether physiologists (i) aim to elucidate function throughout the life cycle, including both early stages and adults, or (ii) focus on adults (in which case early-age survivorship can potentially affect adult characteristics through selection or epigenesis). We establish that Deevey’s Type I curve (which applies to species with relatively limited early mortality) has few or no actual analogs in the real, natural world.
Modular timer networks: abdominal interneurons controlling the chirp and pulse pattern in a cricket calling song
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Chirping male crickets combine a 30 Hz pulse pattern with a 3 Hz chirp pattern to drive the rhythmic opening-closing movements of the front wings for sound production. Lesion experiments suggest two coupled modular timer-networks located along the chain of abdominal ganglia, a network in A3 and A4 generating the pulse pattern, and a network organized along with ganglia A4–A6 controlling the generation of the chirp rhythm. We analyzed neurons of the timer-networks and their synaptic connections by intracellular recordings and staining. We identified neurons spiking in phase with the chirps and pulses, or that are inhibited during the chirps. Neurons share a similar “gestalt”, regarding the position of the cell body, the dendritic arborizations and the contralateral ascending axon. Activating neurons of the pulse-timer network elicits ongoing motor activity driving the generation of pulses; this activity is not structured in the chirp pattern. Activating neurons of the chirp-timer network excites pulse-timer neurons; it drives the generation of chirps and during the chirps the pulse pattern is produced. Our results support the hypothesis that two modular networks along the abdominal ganglion chain control the cricket calling song, a pattern generating network in the mesothoracic ganglion may not be required.
Phenotypic flexibility in heat production and heat loss in response to thermal and hydric acclimation in the zebra finch, a small arid-zone passerine
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

To maintain constant body temperature ( T b ) over a wide range of ambient temperatures ( T a ) endothermic animals require large amounts of energy and water. In hot environments, the main threat to endothermic homeotherms is insufficient water to supply that necessary for thermoregulation. We investigated flexible adjustment of traits related to thermoregulation and water conservation during acclimation to hot conditions or restricted water availability, or both, in the zebra finch, Taeniopygia guttata a small arid-zone passerine. Using indirect calorimetry, we measured changes in whole animal metabolic rate (MR), evaporative heat loss (EHL) and T b before and after acclimation to 23 or 40 °C, with different availability of water. Additionally, we quantified changes in partitioning of EHL into respiratory and cutaneous avenues in birds exposed to 25 and 40 °C. In response to heat and water restriction zebra finches decreased MR, which together with unchanged EHL resulted in increased efficiency of evaporative heat loss. This facilitated more precise T b regulation in heat-acclimated birds. Acclimation temperature and water availability had no effect on the partitioning of EHL into cutaneous or respiratory avenues. At 25 °C, cutaneous EHL accounted for ~ 60% of total EHL, while at 40 °C, its contribution decreased to ~ 20%. Consistent among-individual differences in MR and EHL suggest that these traits, provided that they are heritable, may be a subject to natural selection. We conclude that phenotypic flexibility in metabolic heat production associated with acclimation to hot, water-scarce conditions is crucial in response to changing environmental conditions, especially in the face of current and predicted climate change.
Early-life stress influences ion balance in developing zebrafish (Danio rerio)
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

As a key endocrine axis involved in responding to stress, the hypothalamic–pituitary–interrenal axis plays dual roles in mobilizing energy and maintaining ionic/osmotic balance in fishes. Although these roles have been examined independently in detail in adult fishes, less attention has been paid to the effects of an endogenous stress response during early life, particularly with respect to its potential effects on ionic/osmotic balance. The present study tested the hypothesis that exposure of zebrafish to stress during early development would alter ion balance later in life. Zebrafish at three developmental stages (4, 7, or 15 days post-fertilization, dpf) were subjected to an air-exposure stressor twice a day for 2 days, causing elevation of whole-body cortisol levels. Individuals stressed early in life exhibited decreased survival and growth, altered cortisol responses to a subsequent air-exposure stressor, and increased whole-body Na + and Ca 2+ concentrations. Changes in whole-body Ca 2+ concentrations were accompanied by increased ionocyte abundance at 7 dpf and increased rates of Ca 2+ uptake from the environment. Differences in whole-body ion concentrations at 15 and 35 dpf were not accompanied by altered ion uptake rates. Across all ages examined, air-exposure stress experienced at 7 dpf was particularly effective at eliciting phenotypic changes, suggesting a critical window at this age for a stress response to influence development. These findings demonstrate that early-life stress in zebrafish triggers developmental plasticity, with age-dependent effects on both the cortisol stress axis and ion balance.
Freeze tolerance and the underlying metabolite responses in the Xizang plateau frog, Nanorana parkeri
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

The frog Nanorana parkeri (Dicroglossidae) is endemic to the Tibetan Plateau, and overwinters shallow pond within damp caves for up to 6 months. Herein, we investigate the freeze tolerance of this species and profile changes in liver and skeletal muscle metabolite levels using an untargeted LC–MS-based metabolomic approach to investigate molecular mechanisms that may contribute to freezing survival. We found that three of seven specimens of N. parkeri could survive after being frozen for 12 h at − 2.0 °C with 39.91% ± 5.4% ( n  = 7) of total body water converted to ice. Freezing exposure induced partial dehydration of the muscle, which contributed to decreasing the amount of freezable water within the muscle and could be protective for the myocytes themselves. A comparative metabolomic analysis showed that freezing elicited significant responses, and a total of 33 and 36 differentially expressed metabolites were identified in the liver and muscle, respectively. These metabolites mainly participate in alanine, aspartic acid and glutamic acid metabolism, arginine and proline metabolism, and D-glutamine and D-glutamate metabolism. After freezing exposure, the contents of ornithine, melezitose, and maltotriose rose significantly; these may act as cryoprotectants. Additionally, the content of 8-hydroxy-2-deoxyguanine, 7-Ketocholesterol and hypoxanthine showed a marked increase, suggesting that freezing induced oxidative stress in the frogs. In summary, N. parkeri can tolerate a brief and partial freezing of their body, which was accompanied by substantial changes in metabolomic profiles after freezing exposure.
Hearing in Indian peafowl (Pavo cristatus): sensitivity to infrasound.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Despite the excitement that followed the report of infrasound sensitivity in pigeons 40 years ago, there has been limited followup, with only eleven species of birds having auditory thresholds at frequencies below 250 Hz. With such sparse data on low-frequency hearing, there is little understanding of why some birds hear very low frequencies while others do not. To begin to expand the phylogenetic and ecological sample of low-frequency hearing in birds, we determined the behavioral audiogram of the Indian peafowl, Pavo cristatus. Peafowl are thought to use low frequencies generated by the males' tail feathers and wing flutters during courtship displays, and their crest feathers are reported to resonate at infrasound frequencies. The peafowl were able to respond to frequencies as low as 4 Hz, and their hearing range at 60 dB SPL extended from 29 Hz to 7.065 kHz (7.9 octaves). Removing the crest feathers reduced sensitivity at their resonant frequencies by as much as 7.5 dB, indicating a modest contribution to detectability in that range. However, perforation of the tympanic membranes severely reduced sensitivity to low frequencies, indicating that sensitivity to low frequencies is mediated primarily by the ears and cannot be attributed to some other sensory modality.
Integration of ocular and non-ocular photosensory information in the brain of the terrestrial slug Limax.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

In the terrestrial slugs Limax, most of the photosensory information is thought to be acquired by an eye located on the superior tentacles, by which the slugs avoid light. Recent studies, however, suggested that the brain also plays a role as a photosensor in their negative phototaxis behavior. In the present study, we investigated how the photosensory information acquired by the eye and brain is integrated. The visual pathway in the brain was traced by incorporating tracer molecules from the cut end of an optic nerve, and commissural interactions were found in optic neuropiles located in the lateral regions of the cerebral ganglia. A cluster of neuronal cell bodies located near the dorsal surface of the cerebral ganglion had connections with the contralateral optic neuropile via gap junctions. Some of these neuronal cell bodies were Opn5A-immunoreactive, and contained numerous photic vesicle-like structures. Light-induced spikes were recorded extracellularly from the dorsal surface of these neuronal clusters, and they were synchronous with the spikes recorded from the cut end of the cerebral commissure. This study suggests that both the light information from the eye and the contralateral cerebral ganglion are integrated in the optic neuropile.
Postprandial cardiorespiratory responses and the regulation of digestion-associated tachycardia in Nile tilapia (Oreochromis niloticus)
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Cardiorespiratory adjustments that occur after feeding are essential to supply the demands of digestion in vertebrates. The well-documented postprandial tachycardia is triggered by an increase in adrenergic activity and by non-adrenergic non-cholinergic (NANC) factors in mammals and crocodilians, while it is linked to a withdrawal of vagal drive and NANC factors in non-crocodilian ectotherms—except for fish, in which the sole investigation available indicated no participation of NANC factors. On the other hand, postprandial ventilatory adjustments vary widely among air-breathing vertebrates, with different species exhibiting hyperventilation, hypoventilation, or even no changes at all. Regarding fish, which live in an environment with low oxygen capacitance that requires great ventilatory effort for oxygen uptake, data on the ventilatory consequences of feeding are also scarce. Thus, the present study sought to investigate the postprandial cardiorespiratory adjustments and the mediation of digestion-associated tachycardia in the unimodal water-breathing teleost Oreochromis niloticus . Heart rate ( f H ), cardiac autonomic tones, ventilation rate ( f V ), ventilation amplitude, total ventilation and f H / f V variability were assessed both in fasting and digesting animals under untreated condition, as well as after muscarinic cholinergic blockade with atropine and double autonomic blockade with atropine and propranolol. The results revealed that digestion was associated with marked tachycardia in O. niloticus , determined by a reduction in cardiac parasympathetic activity and by circulating NANC factors—the first time such positive chronotropes were detected in digesting fish. Unexpectedly, postprandial ventilatory alterations were not observed, although digestion triggered mechanisms that were presumed to increase oxygen uptake, such as cardiorespiratory synchrony.
Effects of acute warming on cardiac and myotomal sarco(endo)plasmic reticulum ATPase (SERCA) of thermally acclimated brown trout (Salmo trutta)
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

At high temperatures, ventricular beating rate collapses and depresses cardiac output in fish. The role of sarco(endo)plasmic reticulum Ca 2+ -ATPase (SERCA) in thermal tolerance of ventricular function was examined in brown trout ( Salmo trutta ) by measuring heart SERCA and comparing it to that of the dorsolateral myotomal muscle. Activity of SERCA was measured from crude homogenates of cold-acclimated (+ 3 °C, c.a.) and warm-acclimated (+ 13 °C, w.a.) brown trout as cyclopiazonic acid (20 µM) sensitive Ca 2+ -ATPase between + 3 and + 33 °C. Activity of the heart SERCA was significantly higher in c.a. than w.a. trout and increased strongly between + 3 and + 23 °C with linear Arrhenius plots but started to plateau between + 23 and + 33 °C in both acclimation groups. The rate of thermal inactivation of the heart SERCA at + 35 °C was similar in c.a. and w.a. fish. Activity of the muscle SERCA was less temperature dependent and more heat resistant than that of the heart SERCA and showed linear Arrhenius plots between + 3 and + 33 °C in both c.a. and w.a. fish. SERCA activity of the c.a. muscle was slightly higher than that of w.a. muscle. The rate of thermal inactivation at + 40 °C was similar for both c.a. and w.a. muscle SERCA at + 40 °C. Although the heart SERCA is more sensitive to high temperatures than the muscle SERCA, it is unlikely to be a limiting factor for heart rate, because its heat tolerance, unlike that of the ventricular beating rate, was not changed by temperature acclimation.