nils-herrmann/clean_scirepeval huggingface dataset:
Roles of carbohydrate reserves for local adaptation to low temperatures in the freeze tolerant oligochaete Enchytraeus albidus
Venue: Journal of Comparative Physiology B

Geographic variation in cold tolerance and associated physiological adaptations were investigated in the freeze tolerant enchytraeid Enchytraeus albidus (Oligochaeta). Specimens from Svalbard, Greenland (Nuuk), Iceland (Hólar and Mossfellsbær) and continental Europe [Norway (Bergen), Sweden (Kullen) and Germany] were reared in the laboratory in a common-garden experiment. The aim was to test for variations in minimum lethal temperature, freeze duration tolerance, carbohydrate reserves and metabolic rate among the populations. Cold tolerance was related to environmental temperature of the respective location. Populations from the coldest climatic regions were able to tolerate freezing down to at least −15 °C and endured being frozen at −5 °C for 27–48 days, respectively. Populations from milder climates had a lower freeze duration tolerance (about −9 °C) and endured −5 °C for a shorter period (between 9 and 16 days). Glucose accumulation and glycogen reserves varied significantly between populations, but was not related directly to cold tolerance. Metabolic rate varied significantly between populations, but was not significantly related to cold tolerance. The metabolic rates at −2 °C of frozen and unfrozen worms from Germany and Svalbard were tested. The metabolic depression due to freezing of these populations was relatively small (<50 %), suggesting that the large carbohydrate accumulations may also be important as fuel during long-term freezing at moderately low temperatures. Differences in metabolic depression may partly explain the difference in cold tolerance of these two populations, however, the mechanisms behind local adaptation to low winter temperatures in these enchytraeid populations seem more complex than earlier studies have indicated.
Both PKMζ and KIBRA are closely related to reference memory but not working memory in a T-maze task in rats
Venue: Journal of Comparative Physiology A

Protein kinase M zeta (PKMζ) and the kidney and brain protein (KIBRA) play important roles in various forms of memories. However, whether they are involved in performing the T-maze task is still unknown. In this study, the delayed nonmatch-to-sample (DNMS) task in a T-maze was given to rats. The percentage of correct choices denoting the performance accuracy was calculated and the protein levels of PKMζ and KIBRA in rat’s prefrontal cortex were measured. The results showed significantly increased performance accuracy after the training phase, which was maintained on the next day in groups with a delay of 10 s but not 30 s, indicating that 30 s is too long for rats to maintain working memory. As for the expressions of PKMζ and KIBRA, significant increases were observed 1 day after the training phase, indicating that the formation of reference memory accompanies an increase in PKMζ and KIBRA. No significant difference was found among groups with various delay intervals, indicating that the expressions of PKMζ and KIBRA exert no effects on the performance of working memory. These results provide the first evidence that KIBRA as well as PKMζ is closely related to reference memory but not working memory in rats.
Sequence and expression of an α-amylase gene in four related species of prickleback fishes (Teleostei: Stichaeidae): ontogenetic, dietary, and species-level effects
Venue: Journal of Comparative Physiology B

Partial α-amylase gene sequences were determined and α-amylase gene expression was quantified in four species of carnivorous, omnivorous, and herbivorous prickleback fishes (family Stichaeidae) to assess the effects of ontogeny, diet, and species on expression of this gene. Pairwise comparison of α-amylase nucleotide sequences revealed 96–98 % identity, and comparison of amino acid portions revealed 93–95 % similarity among the four prickleback species. Expression was determined using in situ hybridization and intensity of expression quantified using image analysis. Alpha-amylase expression level was compared in three feeding categories of the four species: (1) small, wild-caught carnivorous juveniles; (2) larger, wild-caught juveniles of the carnivorous species and the three that had shifted to herbivory or omnivory; and (3) larger, juveniles produced by feeding a low-starch artificial diet to small juveniles until they reached the size of the larger wild-caught juveniles. The results showed no dietary effect in any species but significant ontogenetic and species-level effects in Cebidichthys violaceus, as well as in the sister species Xiphister mucosus and X. atropurpureus. Based on a phylogeny for the Stichaeidae produced for this study using two mtDNA genes and one nuclear gene, the ontogenetic dietary shifts to herbivory/omnivory evolved independently in C. violaceus and in the clade containing the two species of Xiphister. All three of these species increased α-amylase gene expression with increase in size and had higher expression than Anoplarchuspurpurescens, which is a member of a third, stichaeid clade comprising carnivores. These results show the importance of α-amylase in the herbivores and omnivores.
Incorporating variability in honey bee waggle dance decoding improves the mapping of communicated resource locations
Venue: Journal of Comparative Physiology A

Honey bees communicate to nestmates locations of resources, including food, water, tree resin and nest sites, by making waggle dances. Dances are composed of repeated waggle runs, which encode the distance and direction vector from the hive or swarm to the resource. Distance is encoded in the duration of the waggle run, and direction is encoded in the angle of the dancer’s body relative to vertical. Glass-walled observation hives enable researchers to observe or video, and decode waggle runs. However, variation in these signals makes it impossible to determine exact locations advertised. We present a Bayesian duration to distance calibration curve using Markov Chain Monte Carlo simulations that allows us to quantify how accurately distance to a food resource can be predicted from waggle run durations within a single dance. An angular calibration shows that angular precision does not change over distance, resulting in spatial scatter proportional to distance. We demonstrate how to combine distance and direction to produce a spatial probability distribution of the resource location advertised by the dance. Finally, we show how to map honey bee foraging and discuss how our approach can be integrated with Geographic Information Systems to better understand honey bee foraging ecology.
Polyunsaturated fats, membrane lipids and animal longevity
Venue: Journal of Comparative Physiology B

Fatty acids are essential for life because they are essential components of cellular membranes. Lower animals can synthesize all four classes of fatty acids from non-lipid sources, but both omega-6 and omega-3 cannot be synthesized de novo by ‘higher’ animals and are therefore essential components of their diet. The relationship between normal variation in diet fatty acid composition and membrane fatty acid composition is little investigated. Studies in the rat show that, with respect to the general classes of fatty acids (saturated, monounsaturated and polyunsaturated) membrane fatty acid composition is homeostatically regulated despite diet variation. This is not the case for fatty acid composition of storage lipids, which responds to diet variation. Polyunsaturated fatty acids are important determinants of physical and chemical properties of membranes. They are the substrates for lipid peroxidation and it is possible to calculate a peroxidation index (PI) for a particular membrane composition. Membrane PI appears to be homeostatically regulated with respect to diet PI. Membrane fatty acid composition varies among species and membrane PI is inversely correlated to longevity in mammals, birds, bivalve molluscs, honeybees and the nematode Caenorhabditis elegans.
Species-specific responses of N homeostasis and electrolyte handling to low N intake: a comparative physiological approach in a monogastric and a ruminant species
Venue: Journal of Comparative Physiology B

In our former studies low crude protein (LCP) intake influenced N homeostasis and electrolyte handling in goats. We hypothesised that due to rumino-hepatic nitrogen (N) recycling adaptation of N homeostasis and adjustment of electrolyte handling to LCP intake differs between goats and monogastric animals. Therefore, an experiment similar to that with goats was conducted with rats. Two feeding groups received a diet either containing 20 or 8 % crude protein (as fed basis) for 5 weeks and intake and excretion of N, calcium (Ca) and phosphorus (P) were determined. To detect systemic and endocrine adaptation to LCP intake plasma concentrations of urea, Ca, phosphate (Pi), insulin-like growth factor 1 (IGF-1), 1,25-dihydroxyvitamin D3 (calcitriol), parathyroid hormone (PTH) and cross-linked telopeptide of type I collagen (CTX) were measured. Adjustment of renal electrolyte transport was assessed by detecting protein expression of key proteins of renal Pi transport. All data were compared with the data of the goat experiment. LCP intake decreased plasma urea concentration stronger in goats than in rats. In both species urinary N excretion declined, but faecal N excretion decreased in goats only. Furthermore, in goats urinary Ca excretion decreased, but in rats urinary Ca concentration increased. Decreased plasma IGF-1 and calcitriol concentrations were found in goats only. Thus, renal Ca excretion appears to be a common target in adaptation of electrolyte homeostasis in both species, but is regulated differently.
Fatty acid mobilization and comparison to milk fatty acid content in northern elephant seals
Venue: Journal of Comparative Physiology B

A fundamental feature of the life history of true seals, bears and baleen whales is lactation while fasting. This study examined the mobilization of fatty acids from blubber and their subsequent partitioning into maternal metabolism and milk production in northern elephant seals (Mirounga angustirostris). The fatty acid composition of blubber and milk was measured in both early and late lactation. Proportions of fatty acids in milk and blubber were found to display a high degree of similarity both early and late in lactation. Seals mobilized an enormous amount of lipid (~66 kg in 17 days), but thermoregulatory fatty acids, those that remain fluid at low temperatures, were relatively conserved in the outer blubber layer. Despite the stratification, the pattern of mobilization of specific fatty acids conforms to biochemical predictions. Long chain (>20C) monounsaturated fatty acids (MUFAs) were the least mobilized from blubber and the only class of fatty acids that showed a proportional increase in milk in late lactation. Polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SFAs) were more mobilized from the blubber, but neither proportion increased in milk at late lactation. These data suggest that of the long chain MUFA mobilized, the majority is directed to milk synthesis. The mother may preferentially use PUFA and SFA for her own metabolism, decreasing the availability for deposition into milk. The potential impacts of milk fatty acid delivery on pup diving development and thermoregulation are exciting avenues for exploration.
A review of the multi-level adaptations for maximizing aerobic dive duration in marine mammals: from biochemistry to behavior
Venue: Journal of Comparative Physiology B

Marine mammals exhibit multi-level adaptations, from cellular biochemistry to behavior, that maximize aerobic dive duration. A dive response during aerobic dives enables the efficient use of blood and muscle oxygen stores, but it is exercise modulated to maximize the aerobic dive limit at different levels of exertion. Blood volume and concentrations of blood hemoglobin and muscle myoglobin are elevated and serve as a significant oxygen store that increases aerobic dive duration. However, myoglobin is not homogeneously distributed in the locomotory muscles and is highest in areas that produce greater force and consume more oxygen during aerobic swimming. Muscle fibers are primarily fast and slow twitch oxidative with elevated mitochondrial volume densities and enhanced oxidative enzyme activities that are highest in areas that produce more force generation. Most of the muscle mitochondria are interfibriller and homogeneously distributed. This reduces the diffusion distance between mitochondria and helps maintain aerobic metabolism under hypoxic conditions. Mitochondrial volume densities and oxidative enzyme activities are also elevated in certain organs such as liver, kidneys, and stomach. Hepatic and renal function along with digestion and assimilation continue during aerobic dives to maintain physiological homeostasis. Most ATP production comes from aerobic fat metabolism in carnivorous marine mammals. Glucose is derived mostly from gluconeogenesis and is conserved for tissues such as red blood cells and the central nervous system. Marine mammals minimize the energetic cost of swimming and diving through body streamlining, efficient, lift-based propulsive appendages, and cost-efficient modes of locomotion that reduce drag and take advantage of changes in buoyancy with depth. Most dives are within the animal’s aerobic dive limit, which maximizes time underwater and minimizes recovery time at the surface. The result of these adaptations is increased breath-hold duration and enhanced foraging ability that maximizes energy intake and minimizes energy output while making aerobic dives to depth. These adaptations are the long, evolutionary legacy of an aquatic lifestyle that directly affects the fitness of marine mammal species for different diving abilities and environments.
Ammonia transport across the skin of adult rainbow trout (Oncorhynchus mykiss) exposed to high environmental ammonia (HEA)
Venue: Journal of Comparative Physiology B

Recent molecular evidence points towards a capacity for ammonia transport across the skin of adult rainbow trout. A series of in vivo and in vitro experiments were conducted to understand the role of cutaneous ammonia excretion (Jamm) under control conditions and after 12-h pre-exposure to high environmental ammonia (HEA; 2 mmol/l NH4HCO3). Divided chamber experiments with bladder-catheterized, rectally ligated fish under light anesthesia were performed to separate cutaneous Jamm from branchial, renal, and intestinal Jamm. Under control conditions, cutaneous Jamm accounted for 4.5 % of total Jamm in vivo. In fish pre-exposed to HEA, plasma total ammonia concentration increased 20-fold to approximately 1,000 μmol/l, branchial Jamm increased 1.5- to 2.7-fold, and urinary Jamm increased about 7-fold. Urinary Jamm still accounted for less than 2 % of total Jamm. Cutaneous Jamm increased 4-fold yet amounted to only 5.7 % of total Jamm in these fish. Genes (Rhcg1, Rhcg2, Rhbg, NHE-2, v-type H+-ATPase) known to be involved in ammonia excretion at the gills of trout were all expressed at the mRNA level in the skin, but their expression did not increase with HEA pre-exposure. In vitro analyses using [14C] methylamine (MA), an ammonia analog which is transported by Rh proteins, demonstrated that MA permeability in isolated skin sections was higher in HEA pre-exposed fish than in control fish. The addition of basolateral ammonia (1,000 μmol/l) to this system abolished this increase in permeability, suggesting ammonia competition with MA for Rh-mediated transport across the skin of HEA pre-exposed trout; this did not occur in skin sections from control trout. Moreover, in vitro Jamm by the skin of fish which had been pre-exposed to HEA was also higher than in control fish in the absence of basolateral ammonia, pointing towards a possible cutaneous ammonia loading in response to HEA. In vitro MA permeability was reduced upon the addition of amiloride (10−4 mol/l), but not phenamil (10−5 mol/l) suggesting a role for a Na/H-exchanger (NHE) in cutaneous ammonia transport, as has been previously described in the skin of larval fish. Overall, it appears that under control conditions and in response to HEA pre-exposure, the skin makes only a very minor contribution to total Jamm, but the observed increases in cutaneous Jamm in vivo and in cutaneous Jamm and MA permeability in vitro demonstrate the capacity for ammonia transport in the skin of adult trout. It remains unclear if this capacity may become significant under certain environmental challenges or if it is merely a remnant of cutaneous transport capacity from early life stages in these fish.
Place learning prior to and after telencephalon ablation in bamboo and coral cat sharks (Chiloscyllium griseum and Atelomycterus marmoratus)
Venue: Journal of Comparative Physiology A

This study assessed complex spatial learning and memory in two species of shark, the grey bamboo shark (Chiloscyllium griseum) and the coral cat shark (Atelomycterus marmoratus). It was hypothesized that sharks can learn and apply an allocentric orientation strategy. Eight out of ten sharks successfully completed the initial training phase (by locating a fixed goal position in a diamond maze from two possible start points) within 14.9 ± 7.6 sessions and proceeded to seven sets of transfer tests, in which sharks had to perform under altered environmental conditions. Transfer tests revealed that sharks had oriented and solved the tasks visually, using all of the provided environmental cues. Unintentional cueing did not occur. Results correspond to earlier studies on spatial memory and cognitive mapping in other vertebrates. Future experiments should investigate whether sharks possess a cognitive spatial mapping system as has already been found in several teleosts and stingrays. Following the completion of transfer tests, sharks were subjected to ablation of most of the pallium, which compromised their previously acquired place learning abilities. These results indicate that the telencephalon plays a crucial role in the processing of information on place learning and allocentric orientation strategies.
The shark Chiloscyllium griseum can orient using turn responses before and after partial telencephalon ablation
Venue: Journal of Comparative Physiology A

This study assessed spatial memory and orientation strategies in Chiloscyllium griseum. In the presence of visual landmarks, six sharks were trained in a fixed turn response. Group 1 started from two possible compartments approaching two goal locations, while group 2 started from and approached only one location, respectively. The learning criterion was reached within 9 ± 5.29 (group 1) and 8.3 ± 3.51 sessions (group 2). Transfer tests revealed that sharks had applied a direction strategy, possibly in combination with some form of place learning. Without visual cues, sharks relied solely on the former. To identify the underlying neural substrate(s), telencephalic were lesioned and performance compared before and after surgery. Ablation of the dorsal and medial pallia only had an effect on one shark (group 1), indicating that the acquisition and retention of previously gained knowledge were unaffected in the remaining four individuals. Nonetheless, the shark re-learned the task. In summary, C. griseum can utilize fixed turn responses to navigate to a goal; there is also some evidence for the use of external visual landmarks while orienting. Probably, strategies can be used alone or in combination. Neither the dorsal nor medial pallium seems to be responsible for the acquisition and processing of egocentric information.
Developmental and physiological challenges of octopus (Octopus vulgaris) early life stages under ocean warming
Venue: Journal of Comparative Physiology B

The ability to understand and predict the effects of ocean warming (under realistic scenarios) on marine biota is of paramount importance, especially at the most vulnerable early life stages. Here we investigated the impact of predicted environmental warming (+3 °C) on the development, metabolism, heat shock response and antioxidant defense mechanisms of the early stages of the common octopus, Octopus vulgaris. As expected, warming shortened embryonic developmental time by 13 days, from 38 days at 18 °C to 25 days at 21 °C. Concomitantly, survival decreased significantly (~29.9 %). Size at hatching varied inversely with temperature, and the percentage of smaller premature paralarvae increased drastically, from 0 % at 18 °C to 17.8 % at 21 °C. The metabolic costs of the transition from an encapsulated embryo to a free planktonic form increased significantly with warming, and HSP70 concentrations and glutathione S-transferase activity levels were significantly magnified from late embryonic to paralarval stages. Yet, despite the presence of effective antioxidant defense mechanisms, ocean warming led to an augmentation of malondialdehyde levels (an indicative of enhanced ROS action), a process considered to be one of the most frequent cellular injury mechanisms. Thus, the present study provides clues about how the magnitude and rate of ocean warming will challenge the buffering capacities of octopus embryos and hatchlings’ physiology. The prediction and understanding of the biochemical and physiological responses to warmer temperatures (under realistic scenarios) is crucial for the management of highly commercial and ecologically important species, such as O. vulgaris.
Odor tracking flight of male Manduca sexta moths along plumes of different cross-sectional area
Venue: Journal of Comparative Physiology A

Males of the hawkmoth, Manduca sexta, track wind-borne plumes of female sex pheromone by flying upwind, while continuously turning from side-to-side and changing altitude. Their characteristic “zigzagging” trajectory has long been thought to result from the interaction of two mechanisms, an odor-modulated orientation to wind and a built-in central nervous system turning program. An interesting and as of yet unanswered question about this tracking behavior is how the cross-section of an odor plume or its clean-air “edges” affects moths’ odor tracking behavior. This study attempts to address this question by video recording and analyzing the behavior of freely flying M. sexta males tracking plumes from pheromone sources of different lengths and orientations with equal odor concentration per unit area. Our results showed that moths generated significantly wider tracks in wide plumes from the longest horizontally-oriented sources as compared to narrower point-source plumes, but had relatively unaltered tracks when orienting to plumes from the same length sources oriented vertically. This suggests that in addition to wind and the presence of pheromones, the area of the plume’s cross section or its edges may also play an important role in the plume tracking mechanisms of M. sexta.