nils-herrmann/clean_scirepeval huggingface dataset:
Metabolic scaling: individual versus intraspecific scaling of Nile tilapia (Oreochromis niloticus).
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

We examined intraspecific scaling of the resting metabolic rate (RMR) of Nile tilapia (Oreochromis niloticus) under different culture conditions and further explored the allometric relationships between organ mass (heart, liver, brain, gills, viscera, and red muscles) and blood parameters (erythrocyte size and red blood cell counts) and body mass. Oreochromis niloticus were bred in individual and group cultures. The scaling exponent of the RMR in the individual cultures was b = 0.620-0.821 (n = 30) and that in the group culture was b = 0.770 [natural logarithm (ln) RMR = 0.770 ln M - 1.107 (n = 76)]. The results of the two experimental methods were similar and were not significantly different from 0.75 (3/4), as predicted by the metabolic theory of ecology. The active and inactive organs were scaled with body mass by an exponent of 0.940 and 1.012, respectively. There was no significant relationship between the blood parameters and body mass. These results suggest that the differences in the culture methods may not have affected the allometric scaling of O. niloticus metabolism. The proportion of active and inactive organs contributed to allometric changes in the metabolic rate with body mass. Red blood cells in fish are not generally representative, and cell size can only partially explain the allometric scaling of metabolism.
Anxiety induces long-term memory forgetting in the crayfish.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

When two male crayfish encounter, agonistic bouts are initiated and a winner-loser relationship is established. Larger animals are more likely to win with their physical advantage, but they are frequently beaten by small dominant animals with previous winning experience. This winner effect remains for several days. In mammals, anxiety impairs learning and induces memory forgetting. In this study, dominant crayfish were exposed to electrical shocks two days after their first win, after which they were paired with large or small naive opponents the following day. Our results showed that electrical shock-applied dominant animals were beaten by large naive opponents, but overcame small naive opponents, suggesting that electrical shocks cause animals to forget their previous winner effect. Electrical shocks appeared to elicit serotonin-mediated anxiety since electrical shocks had no effect on mianserin-injected dominant animals. A 0.5 µM serotonin injection induced a caused anxiety-like reaction, while a 1.0 µM serotonin injection-induced no changes in posture and walking activity. For pairings between dominant and naive animals 1 day after serotonin injection, 0.5 µM serotonin caused similar forgetting of the winner effect, but 1.0 µM serotonin had no effect. Serotonin of low concentrations mediated anxiety and stimulated forgetting of the winner's memory.
The effect of acetazolamide, amiloride, bumetanide and SITS on secretion of fluid and electrolytes by the parotid gland of common wombats, Vombatus ursinus.
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Mechanisms of saliva formation by wombat parotid glands were investigated in anaesthetized wombats at two levels of cholinergically-stimulated flow viz. mid-range (30-40% maximum flow) and maximum flow using ion-transport and carbonic-anhydrase inhibitors. Bumetanide (0.005-0.1 mmol l-1 carotid plasma) progressively reduced mid-range flow by 52 ± 3.4% (mean ± SEM). Concurrently, saliva [Cl] decreased, [Na] and [HCO3] increased but HCO3 excretion was unaltered. Salivary flow during high-rate cholinergic stimulation was 31 ± 1.1% of the pre-bumetanide maximum. During mid-range stimulation, SITS (0.075 mmol l-1) was without effect whereas 0.75 mmol l-1 stimulated transient increases in fluid output. The higher SITS concentration caused no alterations to flow or electrolyte concentrations during maximal stimulation. Carotid plasma [amiloride] (0.05 mmol l-1) caused immediate falls in flow rate of 20-30% followed by progressive recovery over 25 min to levels above pre-amiloride flow rates despite plasma [amiloride] increasing tenfold. Concurrently, salivary [Na] and [Cl] rose to equal plasma concentrations and [K] fell by 50% indicating blockade of acinar Na/H exchangers and luminal Na channels in the ducts. Increased salivary osmolarity caused the flow recovery. Saliva flow during maximum cholinergic stimulation was reduced by 38-46%. The depression of flow was interpreted as resulting from competition between amiloride and acetylcholine for access to the muscarinic receptors. Plasma [acetazolamide] (0.35-2.5 mmol l-1) did not alter saliva outflow during mid-range or maximum flow regimes whereas salivary [Cl] increased and [HCO3] decreased consistent with reduced anion exchange resulting from inhibition of carbonic anhydrase. Combined with bumetanide, acetazolamide (1.5 mmol l-1) reduced flow by an additional 18-22% relative to bumetanide alone thereby demonstrating that acinar HCO3 synthesis supported a limited proportion of saliva formation and that some HCO3 secretion was independent of carbonic anhydrase activity.
Comparison of metabolic scaling between triploid and diploid common carp.
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Ploidy level affects both the cell size and metabolic rate (MR) of organisms. The present study aimed to examine whether ploidy levels cause differences in cell surface area (SA), MR and metabolic scaling. The resting MR (RMR), red blood cell SA (SARBC), red blood cell count (RBCC), gill SA (GSA), and ventilation frequency (VF) were measured in diploid and triploid common carp with different body masses (M). The results showed that both M and ploidy level affected the RMR, GSA, VF, and SARBC, with interactions between M and ploidy level. The triploids had larger SARBC but lower RBCC than those of the diploids. The SARBC increased weakly but significantly with increasing M, by an exponent of 0.043, in the triploids but did not increase in the diploids. The RMR of the triploids and diploids scaled with M, by exponents of 0.696 and 1.007, respectively. The RMR was higher in the triploids than the diploids. The GSA scaled with M, with an exponent of 0.906 in the triploids and an exponent of 1.043 in the diploids. The VF scaled with M by an exponent of - 0.305 in the triploids but showed no correlation with M in the diploids. The larger SARBC and RMR and smaller scaling exponents of both the GSA and VF of the triploids were consistent with the finding that the bR was smaller in the triploids than in the diploids. This suggests that the ploidy-induced changes of SA and SA scaling affect the metabolic scaling of fish.
Enhancement of synaptic responses in ascending interneurones following acquisition of social dominance in crayfish.
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

When crayfish have attained dominant status after agonistic bouts, their avoidance reaction to mechanical stimulation of the tailfan changes from a dart to a turn response. Ascending interneurones originating in the terminal ganglion receive sensory inputs from the tailfan and they affect spike activity of both uropod and abdominal postural motor neurones, which coordinates the uropod and abdominal postural movements. Despite the varying output effects of ascending interneurones, the synaptic responses of all interneurones to sensory stimulation were enhanced when they acquired a dominant state. The number of spikes increased as did a sustained membrane depolarizations. Regardless of social status, the output effects on the uropod motor neurones of all interneurones except VE-1 remained unchanged. VE-1 mainly inhibited the uropod opener motor neurones in naive animals, but tended to excite them in dominant animals. Synaptic enhancement of the sensory response of ascending interneurones was also observed in naive animals treated with bath-applied serotonin. However, subordinate animals or naive animals treated with octopamine had no noticeable effect on the synaptic response of their ascending interneurones to sensory stimulation. Thus, enhancement of the synaptic response is a specific neural event that occurs when crayfish attain social dominance and it is mediated by serotonin.
The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Anthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.
Locomotion and kinematics of arachnids
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

A basic feature of animals is the capability to move and disperse. Arachnids are one of the oldest lineages of terrestrial animals and characterized by an octopodal locomotor apparatus with hydraulic limb extension. Their locomotion repertoire includes running, climbing, jumping, but also swimming, diving, abseiling, rolling, gliding and -passively- even flying. Studying the unique locomotor functions and movement ecology of arachnids is important for an integrative understanding of the ecology and evolution of this diverse and ubiquitous animal group. Beyond biology, arachnid locomotion is inspiring robotic engineers. The aim of this special issue is to display the state of the interdisciplinary research on arachnid locomotion, linking physiology and biomechanics with ecology, ethology and evolutionary biology. It comprises five reviews and ten original research reports covering diverse topics, ranging from the neurophysiology of arachnid movement, the allometry and sexual dimorphism of running kinematics, the effect of autotomy or heavy body parts on locomotor efficiency, and the evolution of silk-spinning choreography, to the biophysics of ballooning and ballistic webs. This closes a significant gap in the literature on animal biomechanics.
Particle size reduction along the digestive tract of fat sand rats (Psammomys obesus) fed four chenopods
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

It is generally accepted that microbial digestion contributes little to digesta particle size reduction in herbivores, and that faecal particle size reflects mainly chewing efficiency, and may vary with diet. Nevertheless, a decrease in mean particle size (MPS) along the gastrointestinal tract (GIT) has been reported, especially in hindgut fermenters. However, to what degree the very fine particle fraction (non-food origin, especially microbes) affects MPS is unclear. Fat sand rats ( Psammomys obesus , diurnal herbivores, n  = 23, 175 ± sd 24 g) consumed one of four chenopods (natural dietary items in the wild) for 30 days. Digestibility was related negatively to dietary fibre content. We determined digesta MPS in the forestomach, glandular stomach, small intestine, caecum, colon and faeces by wet sieving, including (MPS fines ) or excluding (MPS nofines ) particles < 0.25 mm. The proportions of fines were higher and of MPS fines were correspondingly lower in GIT sections that harbour microbes (forestomach, hindgut), whereas MPS nofines did not differ between forestomach and glandular stomach. However, MPS nofines decreased along the GIT, indicating MPS reduction due to digestive (enzymatic and microbial) processes. The four different diets led to different MPS, but the magnitude of MPS reduction in the GIT was not correlated with dietary fibre fractions or dry matter digestibility. These results indicate that within a species, MPS cannot be used as a proxy for diet quality or digestibility, and raise the hypothesis that MPS reduction along the GIT may be more pronounced in smaller than in larger mammalian terrestrial herbivores, possibly due to the fine initial particles produced by chewing in small species.
Role of legs and foot adhesion in salticid spiders jumping from smooth surfaces
Venue: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology

Many spiders and insects can perform rapid jumps from smooth plant surfaces. Here, we investigate how jumping spiders (Pseudeuophrys lanigera and Sitticus pubescens) avoid slipping when accelerating. Both species differed in the relative contribution of leg pairs to the jump. P. lanigera accelerated mainly with their long third legs, whereas their short fourth legs detached earlier. In contrast, S. pubescens accelerated mainly with their long fourth legs, and their short third legs detached earlier. Because of the different orientation (fourth-leg tip pointing backward, third-leg tip pointing forward), the fourth-leg tarsus pushed, whereas the third-leg tarsus pulled. High-speed video recordings showed that pushing and pulling was achieved by different attachment structures. In P. lanigera, third-leg feet made surface contact with setae on their distal or lateral claw tuft, whereas fourth-leg feet engaged the proximal claw tuft, and the distal tuft was raised off the ground. S. pubescens showed the same division of labour between proximal and distal claw tuft for pushing and pulling, but the claw tuft contact lasted longer and was more visible in the fourth than in the third legs. Experimental ablation of claw tufts caused accelerating spiders to slip, confirming that adhesion is essential for jumps from smooth substrates.
Chronic social stress alters protein metabolism in juvenile rainbow trout, Oncorhynchus mykiss
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

When confined in pairs, juvenile rainbow trout (Oncorhynchus mykiss) form dominance hierarchies in which subordinate fish exhibit characteristic physiological changes including reduced growth rates and chronically elevated plasma cortisol concentrations. We hypothesized that alterations in protein metabolism contribute to the reduced growth rate of socially stressed trout, and predicted that subordinate trout would exhibit reduced rates of protein synthesis coupled with increases in protein degradation. Protein metabolism was assessed in dominant and subordinate fish after 4 days of social interaction, and in fish that were separated after 4 days of interaction for a 4 days recovery period, to determine whether effects on protein metabolism recovered when social stress was alleviated. Protein metabolism was assessed in liver and white muscle by measuring the fractional rate of protein synthesis and markers of protein degradation. In the white muscle of subordinate fish, protein synthesis was inhibited and activities of the ubiquitin-proteasome pathway (UPP) and the autophagy lysosomal system (ALS) were elevated. By contrast, the liver of subordinate fish exhibited increased rates of protein synthesis and activation of the ALS. When allowed to recover from chronic social stress for 4 days, differences in protein metabolism observed in white muscle of subordinate fish during the interaction period disappeared. In liver, protein synthesis returned to baseline levels during recovery from social stress, but markers of protein degradation did not. Collectively, these data support the hypothesis that inhibition of muscle protein synthesis coupled with increases in muscle protein breakdown contribute to the reduced growth rates of subordinate rainbow trout.
Reversible thrombocytopenia during hibernation originates from storage and release of platelets in liver sinusoids
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Immobility is a risk factor for thrombosis due to low blood flow, which may result in activation of the coagulation system, recruitment of platelets and clot formation. Nevertheless, hibernating animals—who endure lengthy periods of immobility—do not show signs of thrombosis throughout or after hibernation. One of the adaptations of hemostasis in hibernators consists of a rapidly reversible reduction of the number of circulating platelets during torpor, i.e., the hibernation phase with reduction of metabolic rate, low blood flow and immobility. It is unknown whether these platelet dynamics in hibernating hamsters originate from storage and release, as suggested for ground squirrel, or from breakdown and de novo synthesis. A reduction in detaching forces due to low blood flow can induce reversible adhesion of platelets to the vessel wall, which is called margination. Here, we hypothesized that storage-and-release by margination to the vessel wall induces reversible thrombocytopenia in torpor. Therefore, we transfused labeled platelets in hibernating Syrian hamster (Mesocricetus auratus) and platelets were analyzed using flow cytometry and electron microscopy. The half-life of labeled platelets was extended from 20 to 30 h in hibernating animals compared to non-hibernating control hamsters. More than 90% of labeled platelets were cleared from the circulation during torpor, followed by emergence during arousal which supports storage-and-release to govern thrombocytopenia in torpor. Furthermore, the low number of immature platelets, plasma level of interleukin-1α and normal numbers of megakaryocytes in bone marrow make platelet synthesis or megakaryocyte rupture via interleukin-1α unlikely to account for the recovery of platelet counts upon arousal. Finally, using large-scale electron microscopy we revealed platelets to accumulate in liver sinusoids, but not in spleen or lung, during torpor. These results thus demonstrate that platelet dynamics in hibernation are caused by storage and release of platelets, most likely by margination to the vessel wall in liver sinusoids. Translating the molecular mechanisms that govern platelet retention in the liver, may be of major relevance for hemostatic management in (accidental) hypothermia and for the development of novel anti-thrombotic strategies.
Heat tolerance in desert rodents is correlated with microclimate at inter- and intraspecific levels.
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

Physiological diversity in thermoregulatory traits has been extensively investigated in both endo- and ectothermic vertebrates, with many studies revealing that thermal physiology has evolved in response to selection arising from climate. The majority of studies have investigated how adaptative variation in thermal physiology is correlated with broad-scale climate, but the role of fine-scale microclimate remains less clear . We hypothesised that the heat tolerance limits and evaporative cooling capacity of desert rodents are correlated with microclimates within species-specific diurnal refugia. We tested predictions arising from this hypothesis by comparing thermoregulation in the heat among arboreal black-tailed tree rats (Thallomys nigricauda), Namaqua rock rats (Micaelamys namaquensis) and hairy-footed gerbils (Gerbillurus paeba). Species and populations that occupy hotter diurnal microsites tolerated air temperatures (Ta) ~ 2-4 ℃ higher compared to those species occupying cooler, more thermally buffered microsites. Inter- and intraspecific variation in heat tolerance was attributable to ~ 30% greater evaporative water loss and ~ 44 % lower resting metabolic rates at high Ta, respectively. Our results suggest that microclimates within rodent diurnal refugia are an important correlate of intra- and interspecific physiological variation and reiterate the need to incorporate fine-scale microclimatic conditions when investigating adaptative variation in thermal physiology.
Daily rhythms in the morphometric parameters of hepatocytes and intestine of the European sea bass (Dicentrarchus labrax): influence of feeding time and hepatic zonation.
Venue: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology

The digestive system presents daily rhythms at both physiological and histological levels. Although cell morphology rhythms in mammals have been reported, they have scarcely been investigated in fish. The aim of the present research was to investigate the existence of daily rhythms in the morphology of cells in the liver and intestine of a teleost fish, the European sea bass (Dicentrarchus labrax), and how feeding time influences them. Regarding liver, we also focused on differences between the two metabolic zones: perivenous and periportal. For this purpose, fish were divided into two groups: fish fed once a day in the mid-light phase (ML) or the mid-dark phase (MD). After 1 month under each feeding regime, liver and intestine samples were collected every 4 h during a 24-h cycle, and different parameters were studied by light microscopy and image analysis. Daily rhythms occurred in most of the parameters evaluated in the liver. The effect of feeding time depended on the metabolic zone: the rhythms in the periportal zone were synchronized mainly by the light/dark cycle regardless of feeding time, whereas in the perivenous zone, rhythms were influenced more by feeding time. In the intestine, a daily rhythm in villi height was found with acrophases coinciding with feeding time in each group. These findings show for the first time the existence of cellular morphological rhythms in fish liver and intestine, and highlight the interactions between light and feeding cycles in the different metabolic zones of the liver.