nils-herrmann/clean_scirepeval huggingface dataset:
The effects of steady swimming on fish escape performance
Venue: Journal of Comparative Physiology A

Escape maneuvers are essential to the survival and fitness of many animals. Escapes are frequently initiated when an animal is already in motion. This may introduce constraints that alter the escape performance. In fish, escape maneuvers and steady, body caudal fin (BCF) swimming are driven by distinct patterns of curvature of the body axis. Pre-existing muscle activity may therefore delay or diminish a response. To quantify the performance consequences of escaping in flow, escape behavior was examined in bluegill sunfish (Lepomis macrochirus) in both still-water and during steady swimming. Escapes executed during swimming were kinematically less variable than those made in still-water. Swimming escapes also had increased response latencies and lower peak velocities and accelerations than those made in still-water. Performance was also lower for escapes made up rather than down-stream, and a preference for down-stream escapes may be associated with maximizing performance. The constraints imposed by pre-existing motion and flow, therefore, have the potential to shape predator–prey interactions under field conditions by shifting the optimal strategies for both predators and prey.
Anguillicola crassus impairs the silvering-related enhancements of the ROS defense capacity in swimbladder tissue of the European eel (Anguilla anguilla)
Venue: Journal of Comparative Physiology B

In a process called silvering, European eels prepare for their long-distance migration from European freshwater systems to the Sargasso Sea for reproduction. During this journey, eels perform extended diel vertical migrations, and the concomitant changes in hydrostatic pressure significantly affect the swimbladder, functioning as a buoyancy organ. As the swimbladder is primarily filled with oxygen, the tissue has to cope with extreme hyperoxic conditions, which typically are accompanied by the generation of reactive oxygen species (ROS) and oxidative stress. In addition, since the introduction of the parasitic nematode Anguillicola crassus in the early 1980s, swimbladder function of most of the European eels is impaired by the infection with this parasite. However, the exact pathways to detoxify ROS and how these pathways are affected by silvering or the infection are still unknown. In swimbladder and muscle tissue from uninfected and infected yellow, and from uninfected and infected silver eels, we measured the level of lipid peroxidation, which increases with ROS stress. To assess the capacity of the ROS defense systems, we analyzed the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione reductase (GR), and determined the concentration of the antioxidant glutathione (GSH + GSSG). In swimbladder tissue, we found increased concentrations of GSH + GSSG as well as higher activities of SOD, GPx and GR, suggesting that SOD and the glutathione cycle are important for ROS detoxification. Comparing swimbladder tissue of uninfected yellow with uninfected silver eels, the concentration of GSH + GSSG and the activity of SOD were higher after silvering, corresponding with lower levels of lipid peroxidation. Whereas in yellow eels the infection with A. crassus had no effect, in silver eels the capacity to cope with ROS was significantly impaired. In muscle tissue, silvering or the infection only affected the activity of SOD but in exactly the same way as in swimbladder tissue.
Blood mixtures: impact of puncture site on blood parameters
Venue: Journal of Comparative Physiology B

Various puncture routes, veins, arteries, heart, are used to take blood in animals. For anatomical reasons, differences in blood composition are expected among puncture sites. However, this issue has been rarely assessed and contrasted results have been reported: strong effects of puncture site versus a lack of effect. We captured free-ranging freshwater turtles from different locations to compare the mean concentrations of 12 blood parameters (metabolites, hormone, ions, and enzyme) among three puncture sites: (1) a lateral branch of the jugular vein, (2) a dorsal subcarapacial cervical plexus (sometimes incorrectly referred as the ‘cervical sinus’ in the literature), and (3) a caudal plexus site (sometimes incorrectly referred as the ‘caudal sinus’). Because we used very small syringes (27–30G), we were able to separate lymph, blood, or blood–lymph mixtures. Our results show very strong effects of puncture site and of mixture level (mean maximal difference between sites was 250 %). We also found strong sex and geographical effects. Typically, there were differences in concentrations of blood solutes sampled from the lateral jugular vein and subcarapacial plexus, mainly due to sampling a mixture of blood and lymph from the ‘blood’ at the subcarapacial site and pure blood from the lateral jugular site, and likewise, samples from the caudal site were highly variable due to often sampling a mixture of blood and lymph. These results have technical and fundamental implications, especially when performing comparative analyses. Further, by selecting precise puncture sites, physiological differences between lymph and blood compartments could be investigated.
Seasonal changes in atmospheric noise levels and the annual variation in pigeon homing performance
Venue: Journal of Comparative Physiology A

Repeated releases of experienced homing pigeons from single sites were conducted between 1972 and 1974 near Cornell University in upstate New York and between 1982 and 1983 near the University of Pittsburgh in western Pennsylvania, USA. No annual variation in homing performance was observed at these sites in eastern North America, in contrast to results from a number of similar experiments in Europe. Assuming pigeons home using low-frequency infrasonic signals (~0.1–0.3 Hz), as has been previously proposed, the annual and geographic variability in homing performance within the northern hemisphere might be explained, to a first order, by seasonal changes in low-frequency atmospheric background noise levels related to storm activity in the North Atlantic Ocean, and by acoustic waveguides formed between the surface and seasonally reversing stratospheric winds. In addition, increased dispersion among departure bearings of test birds on some North American release days was possibly caused by infrasonic noise from severe weather events during tornado and Atlantic hurricane seasons.
Enzymatic capacities of metabolic fuel use in cuttlefish (Sepia officinalis) and responses to food deprivation: insight into the metabolic organization and starvation survival strategy of cephalopods
Venue: Journal of Comparative Physiology B

Food limitation is a common challenge for animals. Cephalopods are sensitive to starvation because of high metabolic rates and growth rates related to their “live fast, die young” life history. We investigated how enzymatic capacities of key metabolic pathways are modulated during starvation in the common cuttlefish (Sepiaofficinalis) to gain insight into the metabolic organization of cephalopods and their strategies for coping with food limitation. In particular, lipids have traditionally been considered unimportant fuels in cephalopods, yet, puzzlingly, many species (including cuttlefish) mobilize the lipid stores in their digestive gland during starvation. Using a comprehensive multi-tissue assay of enzymatic capacities for energy metabolism, we show that, during long-term starvation (12 days), glycolytic capacity for glucose use is decreased in cuttlefish tissues, while capacities for use of lipid-based fuels (fatty acids and ketone bodies) and amino acid fuels are retained or increased. Specifically, the capacity to use the ketone body acetoacetate as fuel is widespread across tissues and gill has a previously unrecognized capacity for fatty acid catabolism, albeit at low rates. The capacity for de novo glucose synthesis (gluconeogenesis), important for glucose homeostasis, likely is restricted to the digestive gland, contrary to previous reports of widespread gluconeogenesis among cephalopod tissues. Short-term starvation (3–5 days) had few effects on enzymatic capacities. Similar to vertebrates, lipid-based fuels, putatively mobilized from fat stores in the digestive gland, appear to be important energy sources for cephalopods, especially during starvation when glycolytic capacity is decreased perhaps to conserve available glucose.
Sex and age differences in hibernation patterns of common hamsters: adult females hibernate for shorter periods than males
Venue: Journal of Comparative Physiology B

In this study, we investigated the timing and duration of hibernation as well as body temperature patterns in free-ranging common hamsters (Cricetus cricetus) with regard to sex and age differences. Body temperature was recorded using subcutaneously implanted data loggers. The results demonstrate that although immergence and vernal emergence sequences of sex and age groups resembled those of most hibernators, particularly adult females delayed hibernation onset until up to early January. Thus, in contrast to other hibernators, female common hamsters hibernated for shorter periods than males and correspondingly spent less time in torpor. These sex differences were absent in juvenile hamsters. The period between the termination of hibernation and vernal emergence varied among individuals but did not differ between the sex and age groups. This period of preemergence euthermy was related to emergence body mass: individuals that terminated hibernation earlier in spring and had longer euthermic phases prior to emergence started the active season in a better condition. In addition, males with longer periods of preemergence euthermy had larger testes at emergence. In conclusion, females have to rely on sufficient food stores but may adjust the use of torpor in relation to the available external energy reserves, whereas males show a more pronounced energy-saving strategy by hibernating for longer periods. Nonetheless, food caches seem to be important for both males and females as indicated by the euthermic preemergence phase and the fact that some individuals, mainly yearlings, emerged with a higher body mass than shortly before immergence in autumn.
Training Lymnaea in the presence of a predator scent results in a long-lasting ability to form enhanced long-term memory
Venue: Journal of Comparative Physiology A

Lymnaea exposed to crayfish effluent (CE) gain an enhanced ability to form long-term memory (LTM). We test the hypothesis that a single CE exposure and operant conditioning training leads to long lasting changes in the capability of snails to form LTM when tested in pond water four weeks later. We trained both juvenile and adult snails with a single 0.5 h training session in CE and show that LTM was present 24 h later. Snails trained in a similar manner in just pond water show no LTM. We then asked if such training in CE conferred enhanced memory forming capabilities on these snails four weeks later. That is, would LTM be formed in these snails four weeks later following a single 0.5 h training session in pond water? We found that both adult and juvenile snails previously trained in CE one month previously had enhanced LTM formation abilities. The injection of a DNA methylation blocker, 5-AZA, prior to training in adult snails blocked enhanced LTM formation four weeks later. Finally, this enhanced LTM forming ability was not passed on to the next generation of snails.
Torso, a Drosophila receptor tyrosine kinase, plays a novel role in the larval fat body in regulating insulin signaling and body growth
Venue: Journal of Comparative Physiology B

Torso is a receptor tyrosine kinase whose localized activation at the termini of the Drosophila embryo is mediated by its ligand, Trunk. Recent studies have unveiled a second function of Torso in the larval prothoracic gland (PG) as the receptor for the prothoracicotropic hormone, which triggers pupariation. As such, inhibition of Torso in the PG prolongs the larval growth period, thereby increasing the final pupa size. Here, we report that Torso also acts in the larval fat body, regulating body size in a manner opposite from that of Torso in PG. We confirmed the expression of torso mRNA in the larval fat body and its reduction by RNA interference (RNAi). Fat body-specific knockdown of torso, by either of the two independent RNAi transgenes, significantly decreased the final pupal size. We found that torso knockdown suppresses insulin/target of rapamycin (TOR) signaling in the fat body, as confirmed by repression of Akt and S6K. Notably, the decrease in insulin/TOR signaling and decrease of pupal size induced by the knockdown of torso were rescued by the expression of a constitutively active form of the insulin receptor or by the knockdown of FOXO. Our study revealed a novel role for Torso in the fat body with respect to regulation of insulin/TOR signaling and body size. This finding exemplifies the contrasting effects of the same gene expressed in two different organs on organismal physiology.
Changes in 30K protein synthesis during delayed degeneration of the silk gland by a caspase-dependent pathway in a Bombyx (silkworm) mutant
Venue: Journal of Comparative Physiology B

The silk gland in silkworm (Bombyx mori) is a highly specialized organ that specifically synthesizes silk proteins. A function shift to the synthesis of large quantities of 30K proteins occurs in the degenerating silk gland cells during larval–pupal metamorphosis. The posterior silk gland developmental mutant model of silkworm was used in this study and changes in the programmed cell death (PCD) regulatory signals and 30K protein synthesis during silk gland degeneration were investigated. The results showed that PCD induced by 20-hydroxyecdysone was initiated early during larval–pupal metamorphosis in the mutant, but PCD proceeded slowly, resulting in the degeneration process of the silk gland being extended and took almost twice the time compared with the wild type. Caspase-dependent pathway signals regulated by Dronc in the silk gland cells of the mutant were significantly reduced, while the PCD initiation signal regulated by the Atg family was not delayed or reduced, and PCD-related epigenetic modification such as lysine methylation, acetylation, and succinylation, and tyrosine phosphorylation changed significantly. During the degeneration process in the mutant, 30K proteins were efficiently synthesized in the silk gland cells in stage PP1 even when no caspase protein was detected. Degeneration of the silk gland is a PCD process in which autophagy and apoptosis may participate. The degeneration process was regulated by a caspase-dependent pathway, while the synthesis of 30K proteins along with silk gland degeneration may not be entirely dependent on caspase signals.
Circadian rhythms of clock gene expression in Nile tilapia (Oreochromis niloticus) central and peripheral tissues: influence of different lighting and feeding conditions
Venue: Journal of Comparative Physiology B

The present research aimed to investigate the existence of clock gene expression rhythms in tilapia, their endogenous origin, and how light and feeding cycles synchronize these rhythms. In the first experiment, two groups of fish were kept under an LD cycle and fed at two different time points: in the middle of the light (ML) or in the middle of the dark (MD) phase. In the second experiment, fish fed at ML was fasted and kept under constant lighting (LL) conditions for 1 day. In both experiments, the samples from central (optic tectum and hypothalamus) and peripheral (liver) tissues were collected every 3 h throughout a 24 h cycle. The expression levels of clock genes bmal1a, clock1, per1b, cry2a, and cry5 were analyzed by quantitative PCR. All the clock genes analyzed in brain regions showed daily rhythms: clock1, bmal1a, and cry2a showed the acrophase approximately at the end of the light phase (ZT 8:43-11:22 h), whereas per1b and cry5 did so between the end of the dark phase and the beginning of the light phase, respectively (ZT 21:16-4:00 h). These rhythms persisted under constant conditions. No effect of the feeding time was observed in the brain. In the liver, however, the rhythms of clock1 and cry5 were influenced by feeding, and a shift was observed in the MD fish group (ZT 3:58 h for clock1 and 11:20 h for cry5). This study provides the first insights into the molecular clock of tilapia, a very important fish species for aquaculture. It also reveals the endogenous origin of clock gene rhythms and the ability of feeding time to shift the phase in some clock genes in the peripheral, but not the central, oscillator.
Energy stores, lipid mobilization and leptin endocrinology of rainbow trout
Venue: Journal of Comparative Physiology B

The physiological role of leptin in fish is not fully elucidated. In the present study, the involvement of the leptin system in lipid deposition and mobilization in rainbow trout during feeding and 1, 2 and 4 weeks of fasting was investigated in two lines of rainbow trout with different muscle and visceral adiposity: a fat line (FL) with high total energy reserves, high muscle adiposity, but low visceral adiposity and a lean line (LL) with lower total energy reserves and lower muscle adiposity, but higher visceral adiposity. During 4 weeks of fasting, muscle lipids decreased by 63 % in the FL fish, while no such energy mobilization from muscle occurred in the LL fish. On the other hand, lipid stores in liver and visceral adipose tissue was utilized to a similar extent by the two fish lines during fasting. Under normal feeding conditions, plasma leptin levels were higher in the LL than the FL fish, suggesting a possible contribution of visceral adipocytes to plasma leptin levels. Plasma leptin-binding protein levels did not differ between the lines and were not affected by fasting. After 4 weeks of fasting, the long leptin receptor and the leptin-binding protein isoforms 1 and 3 muscle expression increased in the LL fish, as well as hepatic expression of leptin A1 and the two binding protein isoforms. These responses were not seen in the FL fish. The data suggest that the Lep system in rainbow trout is involved in regulation of energy stores and their mobilization.
Dietary salt loading and ion-poor water exposure provide insight into the molecular physiology of the rainbow trout gill epithelium tight junction complex
Venue: Journal of Comparative Physiology B

This study utilized dietary salt loading and ion-poor water (IPW) exposure of rainbow trout (Oncorhynchus mykiss) to further understand the role of fish gill epithelium tight junction (TJ) physiology in salt and water balance. Gill morphology, biochemistry and molecular physiology were examined, with an emphasis on genes encoding TJ proteins. Fish were either fed a control or salt-enriched diet (~10 % NaCl) for 4 weeks prior to IPW exposure for 24 h. Serum [Na+], [Cl−] and muscle moisture content were unaltered by salt feeding, but changed in response to IPW irrespective of diet. Dietary salt loading altered the morphology (reduced Na+–K+-ATPase-immunoreactive cell numbers and surface exposure of mitochondrion-rich cells), biochemistry (decreased vacuolar-type H+-ATPase activity) and molecular physiology (decreased nkaα1a and cftrII mRNA abundance) of the gill in a manner indicative of reduced active ion uptake activity. But in control fish and not salt-fed fish, gill mRNA abundance of nkaα1c increased and nbc decreased after IPW exposure. Genes encoding TJ proteins were typically either responsive to salt feeding or IPW, but select genes responded to combined experimental treatment (e.g. IPW responsive but only if fish were salt-fed). Therefore, using salt feeding and IPW exposure, new insights into what factors influence gill TJ proteins and the role that specific TJ proteins might play in regulating the barrier properties of the gill epithelium have been acquired. In particular, evidence suggests that TJ proteins in the gill epithelium, or the regulatory networks that control them, respond independently to external or internal stimuli.
Brilliant iridescence of Morpho butterfly wing scales is due to both a thin film lower lamina and a multilayered upper lamina
Venue: Journal of Comparative Physiology A

Butterflies belonging to the nymphalid subfamily, Morphinae, are famous for their brilliant blue wing coloration and iridescence. These striking optical phenomena are commonly explained as to originate from multilayer reflections by the ridges of the wing scales. Because the lower lamina of the scales of related nymphalid butterflies, the Nymphalinae, plays a dominant role in the wing coloration, by acting as a thin film reflector, we investigated single blue scales of three characteristic Morpho species: M. epistrophus, M. helenor and M. cypris. The experimental data obtained by spectrophotometry, scatterometry and scanning electron microscopy demonstrated that also in the Morpho genus the lower lamina of both the cover and ground scales acts as an optical thin film reflector, contributing importantly to the blue structural coloration of the wings. Melanin pigment has a contrast-enhancing function in a sub-class of ground scales.
Periprandial changes and effects of short- and long-term fasting on ghrelin, GOAT, and ghrelin receptors in goldfish (Carassius auratus)
Venue: Journal of Comparative Physiology B

The periprandial profile and effects of short- (7 days) and long-term (30 days) fasting on the ghrelinergic system were studied in goldfish (Carassius auratus). Plasma levels of acyl-ghrelin, desacyl-ghrelin, and ghrelin O-acyl transferase (GOAT) were analyzed by enzymoimmunoassays, and expression of preproghrelin, goat and growth hormone secretagogue receptors (ghs-r) was quantified by real-time PCR. Circulating levels of acyl-ghrelin and GOAT rise preprandially, supporting the role of acyl-ghrelin as a meal initiator in this teleost. Consistently, preproghrelin and ghs-r1a1 expression increases 1 h before feeding time in intestinal bulb, suggesting that this receptor subtype might be involved in the preprandial action of ghrelin in this tissue. Significant postfeeding variations are detected for preproghrelin in telencephalon, goat in telencephalon and hypothalamus, ghs-r1a1 in vagal lobe, ghs-r1a2 and ghs-r2a1 in hypothalamus and ghs-r2a2 in telencephalon and vagal lobe, especially in unfed fish. Short- and long-term fasting significantly increase preproghrelin expression in telencephalon and gut. Goat expression is upregulated by short-term fasting in telencephalon and hypothalamus, and by both short- and long-term fasting in gut. Expression of ghs-r increases by fasting in telencephalon, while an upregulation of type 2, but not type 1, receptors is observed in vagal lobe. In intestinal bulb, ghs-r1a2 transcripts increase after both short- and long-term fasting. These results show a high dependence of the ghrelinergic system on feeding and nutritional status in fish, and demonstrate for the first time a differential implication of the various components of this system suggesting different roles for the four ghrelinergic receptor subtypes.