nils-herrmann/clean_scirepeval huggingface dataset:
Excitatory connections of nonspiking interneurones in the terminal abdominal ganglion of the crayfish
Venue: Journal of Comparative Physiology A

The output effects of the nonspiking interneurones in the crayfish terminal abdominal ganglion upon the uropod motor neurones were characterized using simultaneous intracellular recordings. Inhibitory interactions from nonspiking interneurones to the uropod motor neurones were one-way and chemically mediated. The depolarization of the motor neurones with current injection increased the amplitude of the nonspiking interneurone-mediated hyperpolarization, while hyperpolarization of the motor neurone decreased it. By contrast, excitatory interactions from the nonspiking interneurones to the motor neurones were not mediated via chemical synaptic transmissions. These excitatory connections with the slow motor neurones were one-way while connections with fast motor neurones were bidirectional. Nonspiking interneurone-mediated membrane depolarization of the motor neurones was not affected by the passage of hyperpolarizing current. Each motor neurone spike elicited a time-locked EPSP in the nonspiking interneurones with very short delay (0.2 ms) that suggested electrical coupling between nonspiking interneurones and motor neurones. Nonspiking interneurones directly control the organization of slow motor neurone activity, while they appear to regulate the background activity of the fast motor neurones. A single nonspiking interneurone is possible to inhibit some inter and/or motor neurones via direct chemical synapses and simultaneously excite other neurones via electrical synapses.
Comparisons of two types of teleostean pseudobranchs, silver moony (Monodactylus argenteus) and tilapia (Oreochromis mossambicus), with salinity-dependent morphology and ion transporter expression
Venue: Journal of Comparative Physiology B

There are essentially four different morphological types of pseudobranchs in teleosts, including lamellae-free, lamellae semi-free, covered, and embedded types. In the euryhaline silver moony (Monodactylus argenteus), the pseudobranch belongs to the lamellae semi-free type, which is characterized by one row of filaments on the opercular membrane and fusion on the buccal edge. The pseudobranchial epithelium of the moony contains two types of Na+, K+-ATPase (NKA)-rich cells: chloride cells (CCs) and pseudobranch-type cells (PSCs). Our results revealed increased expression of NKA, the Na+, K+, 2Cl− cotransporter (NKCC), and the cystic fibrosis transmembrane conductance regulator (CFTR) for Cl− secretion and CCs profiles in the pseudobranchs of seawater (SW)-acclimated silver moonies, which indicates the potential role of pseudobranchs containing CCs in hypo-osmoregulation. In contrast, the pseudobranch of the Mozambique tilapia (Oreochromis mossambicus) belongs to the embedded type, which is covered by the connective tissues and only contains PSCs but not CCs. No sign of NKCC and CFTR-immunoreactivity (IR) was found in the pseudobranchs of SW and freshwater (FW) tilapia. However, higher NKA protein expression and larger sizes of NKA-IR PSCs were found in the pseudobranchs of FW-acclimated tilapia. Moreover, in the FW-acclimated moony, NKA-IR PSCs also exhibited higher numbers and larger sizes than in the SW individuals. Taken together, similar responses in low-salinity environments in different types of pseudobranchs indicated that the salinity-dependent morphologies of PSCs might be involved in critical functions for FW teleosts.
Effect of echolocation behavior-related constant frequency–frequency modulation sound on the frequency tuning of inferior collicular neurons in Hipposideros armiger
Venue: Journal of Comparative Physiology A

In constant frequency–frequency modulation (CF–FM) bats, the CF–FM echolocation signals include both CF and FM components, yet the role of such complex acoustic signals in frequency resolution by bats remains unknown. Using CF and CF–FM echolocation signals as acoustic stimuli, the responses of inferior collicular (IC) neurons of Hipposideros armiger were obtained by extracellular recordings. We tested the effect of preceding CF or CF–FM sounds on the shape of the frequency tuning curves (FTCs) of IC neurons. Results showed that both CF–FM and CF sounds reduced the number of FTCs with tailed lower-frequency-side of IC neurons. However, more IC neurons experienced such conversion after adding CF–FM sound compared with CF sound. We also found that the Q20 value of the FTC of IC neurons experienced the largest increase with the addition of CF–FM sound. Moreover, only CF–FM sound could cause an increase in the slope of the neurons’ FTCs, and such increase occurred mainly in the lower-frequency edge. These results suggested that CF–FM sound could increase the accuracy of frequency analysis of echo and cut-off low-frequency elements from the habitat of bats more than CF sound.
Thermoregulation in endotherms: physiological principles and ecological consequences
Venue: Journal of Comparative Physiology B

AbstractIn a seminal study published nearly 70 years ago, Scholander et al. ( 1950) employed Newton’s law of cooling to describe how metabolic rates (MR) in birds and mammals vary predictably with ambient temperature (Ta). Here, we explore the theoretical consequences of Newton’s law of cooling and show that a thermoregulatory polygon provides an intuitively simple and yet useful description of thermoregulatory responses in endothermic organisms. This polygon encapsulates the region in which heat production and dissipation are in equilibrium and, therefore, the range of conditions in which thermoregulation is possible. Whereas the typical U-shaped curve describes the relationship between Ta and MR at rest, thermoregulatory polygons expand this framework to incorporate the impact of activity, other behaviors and environmental conditions on thermoregulation and energy balance. We discuss how this framework can be employed to study the limits to effective thermoregulation and their ecological repercussions, allometric effects and residual variation in MR and thermal insulation, and how thermoregulatory requirements might constrain locomotor or reproductive performance (as proposed, for instance, by the heat dissipation limit theory). In many systems the limited empirical knowledge on how organismal traits may respond to environmental changes prevents physiological ecology from becoming a fully developed predictive science. In endotherms, however, we contend that the lack of theoretical developments that translate current physiological understanding into formal mechanistic models remains the main impediment to study the ecological and evolutionary repercussions of thermoregulation. In spite of the inherent limitations of Newton’s law of cooling as an oversimplified description of the mechanics of heat transfer, we argue that understanding how systems that obey this approximation work can be enlightening on conceptual grounds and relevant as an analytical and predictive tool to study ecological phenomena. As such, the proposed approach may constitute a powerful tool to study the impact of thermoregulatory constraints on variables related to fitness, such as survival and reproductive output, and help elucidating how species will be affected by ongoing climate change.
Functional morphology of the respiratory organs in the cellar spider Pholcus phalangioides (Arachnida, Araneae, Pholcidae)
Venue: Journal of Comparative Physiology B

Morphometric evaluation of the lungs of male and female cellar spiders (Pholcus phalangioideus) was carried out in 2 test groups with different body masses (mean value 10.8, males, and 26.6 mg, females). Males have significant higher lung volume to body mass ratios (2.49 vs. 2.13 × 10−3 cm3 g−1), which might result from the differences in body mass between sexes. Moreover, males have slightly more respiratory surface area per body mass (8.2 vs. 7.7 cm2 g−1) and a little bit larger morphological diffusing capacities for oxygen (9.3 vs. 8.2 nmol s−1 g−1 kPa−1) than females, but both values were not significant. Metabolic rates were measured using flow through respirometry under video tracking: the CO2 release of male and female spiders was measured. Resting rates were 1.7 (males) and 1.5 nmol s−1 g−1 (females). Gluing of one spiracle did not influence the resting metabolic rate. Factorial scopes during stimulation to maximum metabolic rates were about 12 in intact animals, while elimination of one spiracle reduced the factorial scope to 5.2. Comparison with other araneomorph spiders strengthens the hypothesis that tracheae in spiders increase the metabolic rates of the tracheated species and do not only replace reduced lung capacity.
Medullary lateral line units of rudd, Scardinius erythrophthalmus, are sensitive to Kármán vortex streets
Venue: Journal of Comparative Physiology A

AbstractWe investigated the responses of medullary lateral line units of the rudd, Scardinius erythrophthalmus, to bulk water flow (7 cm s−1) and to water flow that contained vortices shed by an upstream half cylinder (diameter 1, 2, and 3 cm). Thirty-five percent of the medullary units
 either increased or decreased their discharge rate with the increasing cylinder diameter. In some units, the spike patterns revealed the vortex shedding frequency, i.e., in these units the amplitude of spike train frequency spectra was similar or identical to the vortex shedding frequency.
Validating the relationship between 3-dimensional body acceleration and oxygen consumption in trained Steller sea lions
Venue: Journal of Comparative Physiology B

We tested the ability of overall dynamic body acceleration (ODBA) to predict the rate of oxygen consumption ($$s\dot{V}_{{{\text{O}}_{2} }}$$sV˙O2) in freely diving Steller sea lions (Eumetopias jubatus) while resting at the surface and diving. The trained sea lions executed three dive types—single dives, bouts of multiple long dives with 4–6 dives per bout, or bouts of multiple short dives with 10–12 dives per bout—to depths of 40 m, resulting in a range of activity and oxygen consumption levels. Average metabolic rate (AMR) over the dive cycle or dive bout calculated was calculated from $$s\dot{V}_{{{\text{O}}_{2} }}$$sV˙O2. We found that ODBA could statistically predict AMR when data from all dive types were combined, but that dive type was a significant model factor. However, there were no significant linear relationships between AMR and ODBA when data for each dive type were analyzed separately. The potential relationships between AMR and ODBA were not improved by including dive duration, food consumed, proportion of dive cycle spent submerged, or number of dives per bout. It is not clear whether the lack of predictive power within dive type was due to low statistical power, or whether it reflected a true absence of a relationship between ODBA and AMR. The average percent error for predicting AMR from ODBA was 7–11 %, and standard error of the estimated AMR was 5–32 %. Overall, the extensive range of dive behaviors and physiological conditions we tested indicated that ODBA was not suitable for estimating AMR in the field due to considerable error and the inconclusive effects of dive type.
The metabolic rate of cultured muscle cells from hybrid Coturnix quail is intermediate to that of muscle cells from fast-growing and slow-growing Coturnix quail
Venue: Journal of Comparative Physiology B

Growth rate is a fundamental parameter of an organism’s life history and varies 30-fold across bird species. To explore how whole-organism growth rate and the metabolic rate of cultured muscle cells are connected, two lines of Japanese quail (Coturnix coturnix japonica), one that had been artificially selected for fast growth for over 60 generations and a control line were used to culture myoblasts. In line with previous work, myoblasts from the fast growth line had significantly higher rates of oxygen consumption, glycolytic flux, and higher mitochondrial volume than myoblasts from the control line, indicating that an increase in growth rate is associated with a concomitant increase in cellular metabolic rates and that mitochondrial density contributes to the differences in rates of metabolism between the lines. We reared chicks from two hybrid lines with reciprocal parental configurations for growth rate to explore the effect of maternally inherited mitochondrial DNA on rates of growth and metabolism. Growth rates of chicks, cellular basal oxygen consumption, glycolytic flux, and mitochondrial volume in myoblasts from chicks from both reciprocal crosses were intermediate to the fast and control lines. This indicates that genes in the nucleus have a strong influence on metabolic rates at the cellular level, compared with maternally inherited mitochondrial DNA.
Adaptive considerations of temperature dependence of neuromuscular function in two species of summer- and winter-caught Crab (Carcinus maenas and Cancerpagurus)
Venue: Journal of Comparative Physiology B

The aim of this study was to determine seasonal differences in the temperature dependence of neuromuscular parameters of the dactylopodite walking leg closer muscle in two species of freshly caught summer and winter decapod crabs. The relatively stenothermal Cancer pagurus (Cp) and eurythermal Carcinus maenas (Cm) muscle resting potential (RP) hyperpolarised significantly with increasing experimental temperature. The muscle RP in Cm was seasonally dependent at acute temperatures above 20 °C whereas in Cp no seasonal effect was observed. The latent period of the muscle excitatory junction potential (EJP) following tonic motor nerve stimulation was significantly longer in winter-caught crabs in both species, although the effect was significantly more marked in Cp than Cm. Summer-caught Cp had larger excitatory junction potentials (EJPs) than did winter-caught crabs, a seasonal effect not seen in Cm. In contrast, marked seasonal differences were found in the EJP decay time constant in Cm having significantly longer time constants in winter-caught crabs, where no seasonal difference was found in Cp. These results suggest that different seasonal effects of neuromuscular parameters between Cm and Cp may reflect different strategies of response to their different seasonal temperature environments.
The influence of turbulence on the sensory basis of rheotaxis
Venue: Journal of Comparative Physiology A

Rheotaxis is a widespread behavior with many potential benefits for fish and other aquatic animals, yet the sensory basis of rheotaxis under different fluvial conditions is still poorly understood. Here, we examine the role that vision and the lateral line play in the rheotactic behavior of a stream-dwelling species (Mexican tetra, Astyanax mexicanus) under both rectilinear and turbulent flow conditions. Turbulence lowered the flow speed at which threshold levels of rheotactic performance were elicited, an effect that was independent of sensory condition. Compared to fish with access to visual information, fish without access exhibited cross-stream casting behaviors and a decrease in the accuracy with which they oriented upstream. Visual deprivation effects were independent of availability of lateral line information and whether flow was rectilinear or turbulent. Fish deprived of lateral line information exhibited no measureable deficits under any of the conditions of this study. This study indicates that rheotactic abilities persist in the absence of both vision and lateral line under both turbulent and non-turbulent conditions, but that turbulence enhances either the motivation or ability of fish to orient to slow currents.
Autonomic control of post-air-breathing tachycardia in Clarias gariepinus (Teleostei: Clariidae)
Venue: Journal of Comparative Physiology B

The African catfish (Clarias gariepinus) is a teleost with bimodal respiration that utilizes a paired suprabranchial chamber located in the gill cavity as an air-breathing organ. Like all air-breathing fishes studied to date, the African catfish exhibits pronounced changes in heart rate (fH) that are associated with air-breathing events. We acquired fH, gill-breathing frequency (fG) and air-breathing frequency (fAB) in situations that require or do not require air breathing (during normoxia and hypoxia), and we assessed the autonomic control of post-air-breathing tachycardia using an infusion of the β-adrenergic antagonist propranolol and the muscarinic cholinergic antagonist atropine. During normoxia, C. gariepinus presented low fAB (1.85 ± 0.73 AB h−1) and a constant fG (43.16 ± 1.74 breaths min−1). During non-critical hypoxia (PO2 = 60 mmHg), fAB in the African catfish increased to 5.42 ± 1.19 AB h−1 and fG decreased to 39.12 ± 1.58 breaths min−1. During critical hypoxia (PO2 = 20 mmHg), fAB increased to 7.4 ± 1.39 AB h−1 and fG decreased to 34.97 ± 1.78 breaths min−1. These results were expected for a facultative air breather. Each air breath (AB) was followed by a brief but significant tachycardia, which in the critical hypoxia trials, reached a maximum of 143 % of the pre-AB fH values of untreated animals. Pharmacological blockade allowed the calculation of cardiac autonomic tones, which showed that post-AB tachycardia is predominantly regulated by the parasympathetic subdivision of the autonomic nervous system.
Representation of particle motion in the auditory midbrain of a developing anuran
Venue: Journal of Comparative Physiology A

In bullfrog tadpoles, a “deaf period” of lessened responsiveness to the pressure component of sounds, evident during the end of the late larval period, has been identified in the auditory midbrain. But coding of underwater particle motion in the vestibular medulla remains stable over all of larval development, with no evidence of a “deaf period.” Neural coding of particle motion in the auditory midbrain was assessed to determine if a “deaf period” for this mode of stimulation exists in this brain area in spite of its absence from the vestibular medulla. Recording sites throughout the developing laminar and medial principal nuclei show relatively stable thresholds to z-axis particle motion, up until the “deaf period.” Thresholds then begin to increase from this point up through the rest of metamorphic climax, and significantly fewer responsive sites can be located. The representation of particle motion in the auditory midbrain is less robust during later compared to earlier larval stages, overlapping with but also extending beyond the restricted “deaf period” for pressure stimulation. The decreased functional representation of particle motion in the auditory midbrain throughout metamorphic climax may reflect ongoing neural reorganization required to mediate the transition from underwater to amphibious life.
Proteomics approaches shed new light on hibernation physiology
Venue: Journal of Comparative Physiology B

The broad phylogenetic distribution and rapid phenotypic transitions of mammalian hibernators imply that hibernation is accomplished by differential expression of common genes. Traditional candidate gene approaches have thus far explained little of the molecular mechanisms underlying hibernation, likely due to (1) incomplete and imprecise sampling of a complex phenotype, and (2) the forming of hypotheses about which genes might be important based on studies of model organisms incapable of such dynamic physiology. Unbiased screening approaches, such as proteomics, offer an alternative means to discover the cellular underpinnings that permit successful hibernation and may reveal previously overlooked, important pathways. Here, we review the findings that have emerged from proteomics studies of hibernation. One striking feature is the stability of the proteome, especially across the extreme physiological shifts of torpor–arousal cycles during hibernation. This has led to subsequent investigations of the role of post-translational protein modifications in altering protein activity without energetically wasteful removal and rebuilding of protein pools. Another unexpected finding is the paucity of universal proteomic adjustments across organ systems in response to the extreme metabolic fluctuations despite the universality of their physiological challenges; rather each organ appears to respond in a unique, tissue-specific manner. Additional research is needed to extend and synthesize these results before it will be possible to address the whole body physiology of hibernation.
Where paths meet and cross: navigation by path integration in the desert ant and the honeybee
Venue: Journal of Comparative Physiology A

Animals that travel large distances in search of food need to be equipped with navigation systems that are capable of keeping track of the distance and direction of travel throughout their outbound journey, so that they may return home expeditiously and without losing their way. The challenge of homing is especially acute when the environment is devoid of landmarks. Desert ants and honeybees are able to meet this challenge, despite their minuscule brains and restricted computational capacity. This article reviews some of the processes and mechanisms that underlie the homing abilities of these creatures, which are among the best-understood navigators in the animal kingdom.
Brooding strategy in fluctuating salinity environments: oxygen availability in the pallial cavity and metabolic stress in females and offspring in the Chilean oyster Ostrea chilensis
Venue: Journal of Comparative Physiology B

Organisms that encounter stressful situations in nature often cope using behavioral (e.g., avoidance) or physiological tactics. In sessile mollusks, the only available behavioral option in dealing with salinity stress is to “clam up”, isolating their tissues from the environment. Though effective in the short term, prolonged isolation can have detrimental physiological consequences, particularly for females brooding embryos in a mantle cavity that is isolated from the external environment. In the Quempillén estuary, the Chilean oyster, Ostrea chilensis, spent nearly one-third of its brooding season at salinities low enough to cause female isolation. When females thus isolated themselves, the dissolved oxygen in their mantle cavity fluid dropped to hypoxic levels within 10 min. In females that were brooding embryos, this depletion of oxygen was not uniform: oxygen was depleted more quickly in the palp region (where embryos accumulate) than in the inhalant region. Additionally, oxygen was reduced even more quickly in the palp region when females were brooding late-stage embryos, which consumed oxygen significantly more quickly than embryos in earlier developmental stages. Finally, O. chilensis used anaerobic metabolism to cope with the hypoxia induced by isolation, as lactate accumulated in the tissues of both females (brooding > non-brooding) and embryos (late stage > early stage). Our findings demonstrate the trade-off between an adaptive avoidance behavior (clamming up) and the potentially detrimental consequences brought on by such a behavior (hypoxia). Cycling of embryos throughout the mantle cavity by deliberate female pumping keeps them from accumulating in the area between the palps, forestalling the creation of hypoxic conditions there. In addition, the capacity for anaerobic metabolism by both females and their embryos should help them tolerate the low oxygen levels that do eventually arise when the pallial cavity is isolated from the surrounding environment during long periods of reduced ambient salinity.