nils-herrmann/clean_scirepeval huggingface dataset:
Difference in glucose tolerance between phytophagous and insectivorous bats
Venue: Journal of Comparative Physiology B

Bats are mostly insectivorous or phytophagous. It is hypothesized that bats are evolved from small insectivorous mammals. Therefore, the digestive and metabolic systems of phytophagous and insectivorous bats must have evolved differently to adapt to their dietary habits. To investigate the difference in sugar tolerance in bats, we determined changes in blood glucose levels after intraperitoneal (i.p.) injection of glucose in three species of phytophagous and four species of insectivorous bats under resting conditions. Results showed that phytophagous bats eliminated blood glucose faster than insectivorous bats. All three species of fruit bats reduced blood glucose to fasting levels within 30–45 min, whereas all insectivorous bats failed to lower blood glucose to fasting levels even 120 min after i.p. glucose injection. Taken together, results of this study suggest that bats have undergone adaptations and become diversified in dietary habits.
Feedforward discharges couple the singing central pattern generator and ventilation central pattern generator in the cricket abdominal central nervous system
Venue: Journal of Comparative Physiology A

We investigated the central nervous coordination between singing motor activity and abdominal ventilatory pumping in crickets. Fictive singing, with sensory feedback removed, was elicited by eserine-microinjection into the brain, and the motor activity underlying singing and abdominal ventilation was recorded with extracellular electrodes. During singing, expiratory abdominal muscle activity is tightly phase coupled to the chirping pattern. Occasional temporary desynchronization of the two motor patterns indicate discrete central pattern generator (CPG) networks that can operate independently. Intracellular recordings revealed a sub-threshold depolarization in phase with the ventilatory cycle in a singing-CPG interneuron, and in a ventilation-CPG interneuron an excitatory input in phase with each syllable of the chirps. Inhibitory synaptic inputs coupled to the syllables of the singing motor pattern were present in another ventilatory interneuron, which is not part of the ventilation-CPG. Our recordings suggest that the two centrally generated motor patterns are coordinated by reciprocal feedforward discharges from the singing-CPG to the ventilation-CPG and vice versa. Consequently, expiratory contraction of the abdomen usually occurs in phase with the chirps and ventilation accelerates during singing due to entrainment by the faster chirp cycle.
Light input pathways to the circadian clock of insects with an emphasis on the fruit fly Drosophila melanogaster
Venue: Journal of Comparative Physiology A

Light is the most important Zeitgeber for entraining animal activity rhythms to the 24-h day. In all animals, the eyes are the main visual organs that are not only responsible for motion and colour (image) vision, but also transfer light information to the circadian clock in the brain. The way in which light entrains the circadian clock appears, however, variable in different species. As do vertebrates, insects possess extraretinal photoreceptors in addition to their eyes (and ocelli) that are sometimes located close to (underneath) the eyes, but sometimes even in the central brain. These extraretinal photoreceptors contribute to entrainment of their circadian clocks to different degrees. The fruit fly Drosophila melanogaster is special, because it expresses the blue light-sensitive cryptochrome (CRY) directly in its circadian clock neurons, and CRY is usually regarded as the fly’s main circadian photoreceptor. Nevertheless, recent studies show that the retinal and extraretinal eyes transfer light information to almost every clock neuron and that the eyes are similarly important for entraining the fly’s activity rhythm as in other insects, or more generally spoken in other animals. Here, I compare the light input pathways between selected insect species with a focus on Drosophila’s special case.
Dietary l-tryptophan modulates agonistic behavior and brain serotonin in male dyadic contests of a cichlid fish
Venue: Journal of Comparative Physiology A

Although some studies have investigated the effects of dietary l-tryptophan on agonistic behavior, research on adult fish specimens is still lacking. Moreover, submissive behaviors have been generally overlooked. We focused on agonistic behavior between males of the cichlid fish Cichlasoma dimerus, in dyadic encounters held in a novel context after being fed or not with an l-tryptophan enriched diet (TRP) for 2 weeks. We arranged three different dyads: control/control (control conditions: not TRP enriched), control/TRP, and TRP/TRP. We also registered the response of the brain serotonergic system in four brain regions. TRP/TRP dyads showed higher latencies to first attack, lower overall aggression, and lower proportions of bites and passive copings (submissive display) compared to control/control. TRP dominant males performed fewer bites with respect to controls, and subordinate males opposed to TRP males showed fewer passive copings. Higher serotonergic activities were found in subordinates’ optic tectum and in the telencephalon and preoptic area/hypothalamus of TRP males. Altogether, results point out that dietary l-tryptophan reduced males’ motivation to attack and dominant aggression, which consequently influenced subordinate agonistic repertory. In addition, males within TRP/TRP dyads showed a switch in their behavioral agonistic repertory. These behavioral outcomes were probably due to modifications at brain serotonergic functioning.
How fly neurons compute the direction of visual motion
Venue: Journal of Comparative Physiology A

Detecting the direction of image motion is a fundamental component of visual computation, essential for survival of the animal. However, at the level of individual photoreceptors, the direction in which the image is shifting is not explicitly represented. Rather, directional motion information needs to be extracted from the photoreceptor array by comparing the signals of neighboring units over time. The exact nature of this process as implemented in the visual system of the fruit fly Drosophila melanogaster has been studied in great detail, and much progress has recently been made in determining the neural circuits giving rise to directional motion information. The results reveal the following: (1) motion information is computed in parallel ON and OFF pathways. (2) Within each pathway, T4 (ON) and T5 (OFF) cells are the first neurons to represent the direction of motion. Four subtypes of T4 and T5 cells exist, each sensitive to one of the four cardinal directions. (3) The core process of direction selectivity as implemented on the dendrites of T4 and T5 cells comprises both an enhancement of signals for motion along their preferred direction as well as a suppression of signals for motion along the opposite direction. This combined strategy ensures a high degree of direction selectivity right at the first stage where the direction of motion is computed. (4) At the subsequent processing stage, tangential cells spatially integrate direct excitation from ON and OFF-selective T4 and T5 cells and indirect inhibition from bi-stratified LPi cells activated by neighboring T4/T5 terminals, thus generating flow-field-selective responses.
Overexpression of isoform B of Dgp-1 gene enhances locomotor activity in senescent Drosophila males and under heat stress
Venue: Journal of Comparative Physiology A

Here, we describe the longevity and locomotor behavior of senescent Drosophila males with altered expression of Dgp-1 gene. In comparison with the wild-type Canton-S (CS) males, six characteristics of the phenotype of Dgp-1[843k] mutant were found: (1) low expression of isoform A; (2) augmented expression of isoform B; (3) reduction in the mean lifespan; (4) decrease in the running speed in 3-day-old flies; (5) maintenance of a high run frequency in senescent flies; and (6) resistance to heat stress manifested as maintenance of a high run frequency at 29 °C. After cessation of “cantonization” process, mean lifespan of the mutant males drifted from low to high values finally exceeding that for CS. In contrast, behavioral phenotype of the mutant was robust. Using the GAL4/UAS system, we showed that neurospecific overexpression of isoform B resulted in a slight decrease of longevity and a high level of run frequency in the senescent flies, similar to that in Dgp-1[843K] mutant. In addition, a decreased level of reactive oxygen species was found in Dgp-1[843K] mutant males maintained under stress conditions. The elevated resistance to oxidative stress probably explains the two distinctive features of the mutation: resistance to aging processes and thermal stress displayed at behavioral level.
The use of evoked potentials to determine sensory sub-modality contributions to acoustic and hydrodynamic sensing
Venue: Journal of Comparative Physiology A

Both the lateral line and the inner ear contribute to near-field dipole source detection in fish. The precise roles these two sensory modalities provide in extracting information about the flow field remain of interest. In this study, evoked potentials (EP, 30–200 Hz) for blind Mexican cavefish were measured in response to a dipole source. Greatest sensitivity was observed at the lower and upper ends of the tested frequency range. To evaluate the relative contributions of the lateral line and inner ear, we measured the effects of neomycin on EP response characteristics at 40 Hz, and used the vital dye DASPEI to verify neuromast ablation. Neomycin increased the latency of the EP response up until 60 min post-treatment. DASPEI results confirmed that neuromast hair cell death was significant in treated fish over this timeframe. These results indicate that the inner ear, whether it is sound pressure or particle motion detection, makes a significant contribution to the dipole-induced EP in blind cavefish at near-field low frequencies where the lateral line contribution would be expected to be strongest. The results from this study imply that under some circumstances, lateral line function could be complemented by the inner ear.
Transcript expression of inward rectifier potassium channels of Kir2 subfamily in Arctic marine and freshwater fish species
Venue: Journal of Comparative Physiology B

Inward rectifier K+ (Kir2) channels are critical for electrical excitability of cardiac myocytes. Here, we examine expression of Kir2 channels in the heart of three Gadiformes species, polar cod (Boreogadus saida) and navaga (Eleginus nawaga) of the Arctic Ocean and burbot (Lota lota) of the temperate lakes to find out the role of Kir2 channels in cardiac adaptation to cold. Five boreal freshwater species: brown trout (Salmo trutta fario), arctic char (Salvelinus alpinus), roach (Rutilus rutilus), perch (Perca fluviatilis) and pike (Esox lucius), and zebrafish (Danio rerio), were included for comparison. Transcript expression of genes encoding Kir2.1a, − 2.1b, − 2.2a, − 2.2b and − 2.4 was studied from atrium and ventricle of thermally acclimated or acclimatized fish by quantitative PCR. Kir2 composition in the polar cod was more diverse than in other species in that all Kir2 isoforms were relatively highly expressed. Kir2 composition of navaga and burbot differed from that of the polar cod as well as from those of other species. The relative expression of Kir2.2 transcripts, especially Kir2.2b, was higher in both atrium and ventricle of navaga and burbot (56–89% from the total Kir2 pool) than in other species (0.1–11%). Thermal acclimation induced only small changes in cardiac Kir2 transcript expression in Gadiformes species. However, Kir2.2b transcripts were upregulated in cold-acclimated navaga and burbot hearts. All in all, the cardiac Kir2 composition seems to be dependent on both phylogenetic position and thermal preference of the fish.
Auditory brainstem responses in the red-eared slider Trachemys scripta elegans (Testudoformes: Emydidae) reveal sexually dimorphic hearing sensitivity
Venue: Journal of Comparative Physiology A

Hearing sensitivity is of general interest from the perspective of understanding the functionality and evolution of vertebrate auditory systems. Sexual dimorphism of auditory systems has been reported in several species of vertebrates, but little is known about this phenomenon in turtles. Some morphological characteristics, such as middle ear and tympanic membrane that influence the hearing sensitivity of animals can result in hearing sexual dimorphism. To examine whether sexual dimorphism in hearing sensitivity occurs in turtles and to compare hearing characteristics with respect to the shape of the tympanic membrane, we measured the hearing sensitivity and tympanum diameter in both sexes of Trachemys scripta elegans. The results showed that, with the exception of 0.9 kHz, auditory brainstem response thresholds were significantly lower in females than in males for frequencies in the 0.2–1.1 kHz range, indicating that the hearing of females shows greater sensitivity. No significant differences were detected in the tympanum diameter of both sexes. These results showed that sexually dimorphic hearing sensitivity has evolved in turtles; however, this difference does not appear to be related to differences in the size of the tympanic membrane. The possible origin and function of the sexual differences in auditory characteristic are discussed.
Links between muscle phenotype and life history: differentiation of myosin heavy chain composition and muscle biochemistry in precocial and altricial pinniped pups
Venue: Journal of Comparative Physiology B

In marine mammals, muscular development has been identified as a rate-limiting factor in achieving adult dive capacities. This study investigates the rate that myosin heavy chain (MHC) composition matures in a postural and locomotor skeletal muscle for four pinniped species with different lactation lengths: hooded seals, Cystophora cristata; harp seals, Pagophilus groenlandicus; northern fur seals, Callorhinus ursinus, and Steller sea lions, Eumetopias jubatus. The ontogeny of MHC isoform expression was compared with developmental rates of myoglobin concentrations, and aerobic (citrate synthase, β-hydroxyacyl-CoA dehydrogenase) and anaerobic (lactate dehydrogenase) enzyme activities. Within taxonomic families, species with shorter lactation periods had more mature muscles biochemically at birth, and fiber types differentiated earlier during ontogeny (Phocidae: hooded > harp seals, Otariidae: northern fur seals > Steller sea lions). Northern fur seal neonates had the most phenotypically-mature muscles in this study, with no immature MHC isoforms. The relationship between muscle biochemistry and MHC composition became more pronounced with age, and developed to reflect swimming mode and activity levels. In adults, phocids had more slow-twitch oxidative protein in their primary locomotor muscle, the Longissimus dorsi (LD), than otariids which likely reflects oxygen-sparing strategies for the phocids’ longer dives. Conversely, northern fur seal muscles had higher proportions of fast-twitch MHCs in the Pectoralis and LD, likely indicative of this species’ smaller size and higher mass-specific metabolic rates. Thus, muscle phenotype is linked with species life history, and a mismatch between muscle biochemistry and MHC composition at weaning has important implications for the first year of independent foraging in pinniped pups.
The variable heartbeat of Japanese moles (Mogera spp.)
Venue: Journal of Comparative Physiology B

This report demonstrates the variable cardiac rhythm in two species of subterranean mole, the large Japanese mole (Mogera wogura) and the lesser Japanese mole (Mogera imaizumii). The phenomenon was revealed using X-ray videos of M. wogura and investigated in detail using electrocardiogram (ECG) traces recorded with implanted electrodes in this species and M. imaizumii. Cessation of heartbeat and extended R–R intervals were observed in the ECGs from both species during short bouts of rest in wakeful specimens of both species under normoxic conditions at room temperature. The mean durations of R–R intervals were 288.8 ± 3.3 ms for M. wogura and 191.9 ± 2.4 ms for M. imaizumii. The cardiac rhythm in both species became more unstable and R–R interval was prolonged by 153.5% ± 17.7 after injection of a sympathetic blocker (propranolol), whereas the application of a parasympathetic blocker (atropine) resulted in increasing stability and a reduced interval between R wave peaks (R–R) 64.2% ± 4.8. ECGs of two related soricomorphs, the fossorial Japanese shrew-mole (Urotrichus talpoides) and surface-dwelling Japanese white-toothed shrew (Crocidura dsinezumi) were also recorded and compared for comparison. The heartbeats of these species were relatively stable compared with those of the subterranean moles. Our results indicated clear differences in the physiological cardiac features between the examined members of the Soricomorpha.
Calcium absorption in the fluted giant clam, Tridacna squamosa, may involve a homolog of voltage-gated calcium channel subunit α1 (CACNA1) that has an apical localization and displays light-enhanced protein expression in the ctenidium
Venue: Journal of Comparative Physiology B

In light, giant clams can increase rates of shell formation and growth due to their symbiotic relationship with phototrophic zooxanthellae residing extracellularly in a tubular system. Light-enhanced shell formation necessitates increase in the uptake of Ca2+ from the ambient seawater and the supply of Ca2+ through the hemolymph to the extrapallial fluid, where calcification occurs. In this study, the complete coding cDNA sequence of a homolog of voltage-gated calcium channel subunit α1 (CACNA1), which is the pore-forming subunit of L-type voltage-gated calcium channels (VGCCs), was obtained from the ctenidium (gill) of the giant clam, Tridacna squamosa. It consisted of 6081 bp and encoded a 223 kDa polypeptide with 2027 amino acids, which was characterized as the α1D subunit of L-type VGCC. Immunofluorescence microscopy demonstrated that CACNA1 had an apical localization in the epithelial cells of filaments and tertiary water channels in the ctenidium of T. squamosa, indicating that it was well positioned to absorb exogenous Ca2+. Additionally, there was a significant increase in the protein abundance of CACNA1 in the ctenidium of individuals exposed to light for 12 h. With more pore-forming CACNA1, there could be an increase in the permeation of exogenous Ca2+ into the ctenidial epithelial cells through the apical membrane. Taken together, these results denote that VGCC could augment exogenous Ca2+ uptake through the ctenidium to support light-enhanced shell formation in T. squamosa. Furthermore, they support the proposition that light-enhanced phenomena in giant clams are attributable primarily to the direct responses of the host’s transporters/enzymes to light, in alignment with the symbionts’ phototrophic activity.
Level-dependent masking of the auditory evoked responses in a dolphin: manifestation of the compressive nonlinearity
Venue: Journal of Comparative Physiology A

At suprathreshold sound levels, interactions between masking noise and sound signals are liable to compressive nonlinearity in the auditory system. The compressive nonlinearity is a property of the “active” cochlear mechanism. It is not known whether this mechanism is capable to function at frequencies close to or above 100 kHz that are available to odontocetes (toothed whales, dolphins, and porpoises). This question may be answered by the use of the frequency-specific masking. Auditory evoked potentials to sound stimuli in a bottlenose dolphin, Tursiops truncatus, were recorded in the presence of simultaneous maskers. Stimulus frequencies were 45, 64, or 90 kHz. Maskers were on-frequency bandlimited noise or low-frequency noise of frequencies 0.25–1 oct below the stimulus frequency. The stimuli provoked responses as a series of brain-potential waves following the pip-train rate. For the on-frequency masker, the masker level at threshold dependence on the signal level was 1.1 dB/dB. For maskers of 1 oct below the stimulus, the dependence was 0.53–0.57 dB/dB. The data considered evidence for the compressive nonlinearity of responses to stimuli, and therefore, are indicative of the functioning of the active mechanism at frequencies up to 90 kHz.
A robust diving response in the laboratory mouse
Venue: Journal of Comparative Physiology B

The diving response is a coordinated physiological response to submersion under water and has been documented amongst all mammals tested to date. The physiological response consists of three primary reflexes: an immediate bradycardia, apnea, and selective constriction of peripheral blood vessels. We hypothesized that mice would exhibit a diving response upon voluntary submersion into water typically seen in other mammals. In this study, telemeters that measure arterial pressure were implanted into male and female C57Bl/6J mice. These mice were trained to voluntarily dive underwater for a distance of 40 cm over a 4–6 s period. Just before the dive, the interbeat interval (IBI) was 87 ± 6 ms (mean ± SD) and diastolic pressure was 99 ± 14 mmHg. Underwater submersion caused (1) a dramatic bradycardia immediately at the onset of each dive, as IBI increased to 458 ± 104 ms, and (2) a large drop in diastolic pressure, to 56 ± 16 mmHg despite the elevation in peripheral resistance. Mice experienced a short bout (~ 2 s) of hypertension (diastolic pressure rose to 131 ± 17 mmHg) upon emergence. The bradycardia and hypotension appeared to be vagally mediated, since both these responses were blocked with atropine pre-treatment. These data demonstrate that the mouse exhibits a robust diving response upon voluntary submersion into water.
Ventilatory responses of the clown knifefish, Chitala ornata, to arterial hypercapnia remain after gill denervation
Venue: Journal of Comparative Physiology B

The aim of this study was to corroborate the presence of CO2/H+-sensitive arterial chemoreceptors involved in producing air-breathing responses to aquatic hypercarbia in the facultative air-breathing clown knifefish (Chitala ornata) and to explore their possible location. Progressively increasing levels of CO2 mixed with air were injected into the air-breathing organ (ABO) of one group of intact fish to elevate internal PCO2 and decrease blood pH. Another group of fish in which the gills were totally denervated was exposed to aquatic hypercarbia (pH ~ 6) or arterial hypercapnia in aquatic normocarbia (by injection of acetazolamide to increase arterial PCO2 and decrease blood pH). Air-breathing frequency, gill ventilation frequency, heart rate and arterial PCO2 and pH were recorded during all treatments. The CO2 injections into the ABO induced progressive increases in air-breathing frequency, but did not alter gill ventilation or heart rate. Exposure to both hypercarbia and acetazolamide post-denervation of the gills also produced significant air-breathing responses, but no changes in gill ventilation. While all treatments produced increases in arterial PCO2 and decreases in blood pH, the modest changes in arterial PCO2/pH in the acetazolamide treatment produced the greatest increases in air-breathing frequency. These results strengthen the evidence that internal CO2/H+ sensing is involved in the stimulation of air breathing in clown knifefish and suggest that it involves extra-branchial chemoreceptors possibly situated either centrally or in the air-breathing organ.