nils-herrmann/clean_scirepeval huggingface dataset:
Programming of offspring sex ratios by maternal stress in humans: assessment of physiological mechanisms using a comparative approach
Venue: Journal of Comparative Physiology B

Sex ratio adjustment has become a hot topic in ecology and evolutionary biology, as documentations of sex ratio skews are numerous, and include examples in diverse animal species. Over the past several decades, scientists have repeatedly debated whether human sex ratios also significantly deviate toward one sex or the other based on environmental or social conditions. An increasing number of studies supports the idea that exposure to stressful conditions can influence the sexes of offspring produced by humans, a majority of which document significantly fewer males after exposure to adverse conditions such as severe life events, economic disruption, or natural disasters. From a comparative standpoint, these findings are similar to studies in non-human mammals and other vertebrate species showing a bias toward females during times of stress. However, the mechanisms by which stress-related biases in the offspring sex ratio may occur remain elusive, and the involvement of glucocorticoids indicating a true influence of stress itself remains unstudied. Here, I review the evidence that stressful events induce sex ratio adjustment in humans. Additionally, I discuss the possibility for glucocorticoid mediation of sex ratio adjustment and the potential reproductive stages during which stress-induced sex ratio adjustment may occur in humans and other mammals.
Endogenous origin of endo-β-1,4-glucanase in common woodlouse Porcellio scaber (Crustacea, Isopoda)
Venue: Journal of Comparative Physiology B

Because endogenous cellulases have been observed in arthropods, the potential ability to produce cellulose degrading enzymes was examined in the terrestrial isopod Porcellio scaber, an important decomposer of decayed plant material. cDNA fragments encoding portions of two novel endo-β-1,4-glucanase amino acid sequences were amplified by RT-PCR, and the amino acid sequences predicted were affiliated to endo-β-1,4-glucanases from other arthropods, where they cluster with endo-β-1,4-glucanases of decapod crustaceans. Hybridization in situ reveals the hepatopancreas to be the primary site of gene expression and provides direct evidence of the endogenous origin of endo-β-1,4-glucanase in P. scaber. Conservation of catalytically important amino acid residues suggests that both sequences translate into functional cellulases. Cellulolytic activity was detected in hepatopancreatic extract after separation by SDS-PAGE, which included CMC as substrate. This is the first evidence of endogenous cellulases in peracarid crustaceans and gives strong support for the involvement of isopod endo-β-1,4-glucanases in the degradation of cellulose in their diet.
Redox homeostasis and respiratory metabolism in camels (Camelus dromedaries): comparisons with domestic goats and laboratory rats and mice
Venue: Journal of Comparative Physiology B

We have previously reported the occurrence of multiple forms of drug-metabolizing enzymes in camel tissues. Here, we investigate glutathione (GSH)-dependent redox homeostasis, reactive oxygen species (ROS) production and mitochondrial respiratory functions in camel tissues and compare them with imported domestic goats and laboratory rats and mice. Cytochrome P450 2E1 (CYP 2E1) and GSH-metabolizing enzymes were differentially expressed in the liver and kidney of these animals. Camel liver has significantly lower GSH pool than that in goats, rats and mice. Mitochondria isolated from the tissues of these animals showed a comparable ability to metabolize specific substrates for respiratory enzyme complexes I, II/III and IV. These complexes were metabolically more active in the kidney than in the liver of all the species. Furthermore, the activity of complex IV in camel tissues was significantly lower than in other species. On the other hand, complex II/III activity in camel kidney was higher compared to the other species. In addition, as expected, we observed that inhibitors of these enzyme complexes augment the production of mitochondrial ROS in camel and goat tissues. These results help to better understand the metabolic ability and adaptation in desert camels in comparison with domestic goats and laboratory rats and mice since they are exposed to different environmental and dietary conditions. Our study may also have implications in the pharmacology and toxicology of drugs and pollutants in these species.
Regulation of glucose-6-phosphate dehydrogenase by reversible phosphorylation in liver of a freeze tolerant frog
Venue: Journal of Comparative Physiology B

Glucose-6-phosphate dehydrogenase (G6PDH) and the pentose phosphate pathway play a key role in reductive biosynthesis and antioxidant defense, while diverting glucose from other cellular functions. G6PDH was isolated from liver of the wood frog, Rana sylvatica, a freeze tolerant species that uses glucose as a cryoprotectant. Analysis of kinetic parameters (Km and Vmax) of G6PDH showed a significant increase in Km G6P (from 98.2 ± 3.8 to 121 ± 5.3 μM) and Km NADP+ (from 65.5 ± 2.3 to 89.1 ± 4.8 μM) in frogs following freezing exposure, indicating lower affinity for G6PDH substrates in this state. Subsequent analyses indicated that differential phosphorylation of G6PDH between the two states was responsible for the altered kinetic properties. Thus, two differentially charged forms of G6PDH were resolved by DEAE ion-exchange chromatography and, compared with controls, the proportion of G6PDH activity in peak I decreased and in peak II increased in liver from frozen frogs. G6PDH in peak I had a Km G6P of 94.1 ± 1.1 μM and Km NADP+ of 61.2 ± 3.5 μM, whereas Peak II G6PDH showed higher values (Km G6P was 172 ± 4.3 μM, Km NADP+ was 98.2 ± 3.3 μM). G6PDH from each peak was incubated with ions and second messengers to stimulate the actions of protein kinases with results indicating that G6PDH can be phosphorylated by protein kinase G, protein kinase C, AMP-activated protein kinase, or calmodulin-dependent protein kinase. The data indicate that in control frogs, G6PDH is in a high phosphate form and displays a high substrate affinity, whereas in frozen frogs G6PDH is less phosphorylated, with lower substrate affinity.
Raphe modulation of the pre-Bötzinger complex respiratory bursts in in vitro medullary half-slice preparations of neonatal mice
Venue: Journal of Comparative Physiology A

Spontaneous respiratory bursts which begin in the pre-Bötzinger complex were recorded from the hypoglossal (XIIth) nerve rootlets of in vitro slices prepared from newborn mice. First, we examined the respiratory bursts before and after a midline or para-midline transection which spared the caudal raphe nuclei: the raphe obscurus and raphe pallidus. After a midline transection, the respiratory bursts in both half-slices were desynchronized and had slightly decreased amplitudes and frequencies. After a para-midline transection, the bursts continued with similar frequencies in the half slice containing the raphe obscurus and raphe pallidus. Second, to analyze the effects of modulation by the raphe obscurus and raphe pallidus, a dorsal or ventral midline lesion was used to damage either the raphe obscurus or raphe pallidus. After a dorsal lesion, the synchronized respiratory bursts persisted with slightly decreased frequencies. In contrast, after a ventral lesion, the bursts were almost completely abolished, but recovered significantly after the addition of 5-HT. The present results demonstrated that the pre-Bötzinger complex on each side of the medulla can independently generate rhythmic respiratory activity. It is suggested that the 5-HT released from the ventral part of the raphe nuclei (predominantly the raphe pallidus) plays a critical role in sustaining rhythmic respiratory bursts.
Pheromonal communication in amphibians
Venue: Journal of Comparative Physiology A

Pheromonal communication is widespread in salamanders and newts and may also be important in some frogs and toads. Several amphibian pheromones have been behaviorally, biochemically and molecularly identified. These pheromones are typically peptides or proteins. Study of pheromone evolution in plethodontid salamanders has revealed that courtship pheromones have been subject to continual evolutionary change, perhaps as a result of co-evolution between the pheromonal ligand and its receptor. Pheromones are detected by the vomeronasal organ and main olfactory epithelium. Chemosensory neurons express vomeronasal receptors or olfactory receptors. Frogs have relatively large numbers of vomeronasal receptors that are transcribed in both the vomeronasal organ and the main olfactory epithelium. Salamander vomeronasal receptors apparently are restricted to the vomeronasal organ. To date, no chemosensory ligands have been matched to vomeronasal receptors or olfactory receptors so it is unknown whether particular receptor types are (1) specialized for detection of pheromones versus other chemosignals, or (2) specialized for detection of volatile, nonvolatile, or water-borne chemosignals. Despite progress in understanding amphibian pheromonal communication, only a small fraction of amphibian species have been examined. Study of additional species of amphibians will indicate which traits related to pheromonal communication are evolutionarily conserved and which traits have diverged over time.
An expanded set of photoreceptors in the Eastern Pale Clouded Yellow butterfly, Colias erate
Venue: Journal of Comparative Physiology A

We studied the spectral and polarisation sensitivities of photoreceptors of the butterfly Colias erate by using intracellular electrophysiological recordings and stimulation with light pulses. We developed a method of response waveform comparison (RWC) for evaluating the effective intensity of the light pulses. We identified one UV, four violet-blue, two green and two red photoreceptor classes. We estimated the peak wavelengths of four rhodopsins to be at about 360, 420, 460 and 560 nm. The four violet-blue classes are presumably based on combinations of two rhodopsins and a violet-absorbing screening pigment. The green classes have reduced sensitivity in the ultraviolet range. The two red classes have primary peaks at about 650 and 665 nm, respectively, and secondary peaks at about 480 nm. The shift of the main peak, so far the largest amongst insects, is presumably achieved by tuning the effective thickness of the red perirhabdomal screening pigment. Polarisation sensitivity of green and red photoreceptors is higher at the secondary than at the main peak. We found a 20-fold variation of sensitivity within the cells of one green class, implying possible photoreceptor subfunctionalisation. We propose an allocation scheme of the receptor classes into the three ventral ommatidial types.
Separating the effects of prey size and speed on the kinematics of prey capture in the omnivorous lizard Gerrhosaurus major
Venue: Journal of Comparative Physiology A

Feeding behavior is known to be modulated as prey properties change. During prey capture, external prey properties, including size and mobility, are likely some of the most important components in predator–prey interactions. Whereas prey size has been demonstrated to elicit modulation of jaw movements during capture, how prey speed affects the approach and capture of prey remains unknown. We quantified the kinematics associated with movements of both the feeding and locomotor systems during prey capture in a lizard, Gerrhosaurus major, while facing prey differing in size and mobility (newborn mice, grasshoppers, and mealworms). Our data show that the feeding and locomotor systems were recruited differently in response to changes in the size or speed of the prey. The timing of jaw movements and of the positioning of the head are affected by changes in prey size—and speed, to a lesser extent. Changes in prey speed resulted in concomitant changes in the speed of strike and an early and greater elevation of the neck. External prey properties, and prey mobility in particular, are relevant in predator–prey interactions and elicit specific responses in different functional systems.
Metabolic and molecular stress responses of gilthead seam bream Sparus aurata during exposure to low ambient temperature: an analysis of mechanisms underlying the winter syndrome
Venue: Journal of Comparative Physiology B

The winter syndrome in the gilthead sea bream Sparus aurata indicates that the species is exposed to critically low temperatures in Mediterranean aquaculture in winter. The present study of metabolic patterns and molecular stress responses during cold exposure was carried out to investigate this “disease”, in light of the recent concept of oxygen and capacity limited thermal tolerance. The metabolic profile of fuel oxidation was examined by determining the activities of the enzymes hexokinase (HK), aldolase (Ald), pyruvate kinase (PK), l-lactate dehydrogenase (l-LDH), citrate synthase (CS), malate dehydrogenase (MDH) and 3-hydroxyacyl CoA dehydrogenase (HOAD) in heart, red and white muscle after exposure to temperatures of 10, 14 and 18°C. Especially, the increase in LDH activity combined with the accumulation of l-lactate in tissues indicates that temperatures below 14°C are critical for Sparus aurata and stimulate the anaerobic component of metabolism. Increase in the activity of HOAD suggests that oxidation of free fatty acids might contribute to ATP turnover at low temperatures. The expression of Hsp70 and Hsp90 in all tissues examined revealed a cellular stress response during cooling below 18°C. In the light of winter temperatures in S. aurata cultures around 10°C, our data suggest that the fish are exposed to stressful conditions at the low end of their thermal tolerance window. These conditions likely impair the aerobic capacity of the fish, compromise the rates of growth and reproduction and may contribute to elicit pathological conditions.
Olfactory learning in the stingless bee Tetragonisca angustula (Hymenoptera, Apidae, Meliponini)
Venue: Journal of Comparative Physiology A

Tetragonisca angustula stingless bees are considered as solitary foragers that lack specific communication strategies. In their orientation towards a food source, these social bees use chemical cues left by co-specifics and the information obtained in previous foraging trips by the association of visual stimuli with the food reward. Here, we investigated their ability to learn the association between odors and reward (sugar solution) and the effect on learning of previous encounters with scented food either inside the hive or during foraging. During food choice experiments, when the odor associated with the food was encountered at the feeding site, the bees’ choice is biased to the same odor afterwards. The same was not the case when scented food was placed inside the nest. We also performed a differential olfactory conditioning of proboscis extension response with this species for the first time. Inexperienced bees did not show significant discrimination levels. However, when they had had already interacted with scented food inside the hive, they were able to learn the association with a specific odor. Possible olfactory information circulation inside the hive and its use in their foraging strategies is discussed.
Variation in the daily rhythm of body temperature of free-living Arabian oryx (Oryx leucoryx): does water limitation drive heterothermy?
Venue: Journal of Comparative Physiology B

Heterothermy, a variability in body temperature beyond the limits of homeothermy, has been advanced as a key adaptation of Arabian oryx (Oryx leucoryx) to their arid-zone life. We measured body temperature using implanted data loggers, for a 1-year period, in five oryx free-living in the deserts of Saudi Arabia. As predicted for adaptive heterothermy, during hot months compared to cooler months, not only were maximum daily body temperatures higher (41.1 ± 0.3 vs. 39.7 ± 0.1°C, P = 0.0002) but minimum daily body temperatures also were lower (36.1 ± 0.3 vs. 36.8 ± 0.2°C, P = 0.04), resulting in a larger daily amplitude of the body temperature rhythm (5.0 ± 0.5 vs. 2.9 ± 0.2°C, P = 0.0007), while mean daily body temperature rose by only 0.4°C. The maximum daily amplitude of the body temperature rhythm reached 7.7°C for two of our oryx during the hot-dry period, the largest amplitude ever recorded for a large mammal. Body temperature variability was influenced not only by ambient temperature but also water availability, with oryx displaying larger daily amplitudes of the body temperature rhythm during warm-dry months compared to warm-wet months (3.6 ± 0.6 vs. 2.3 ± 0.3°C, P = 0.005), even though ambient temperatures were the same. Free-living Arabian oryx therefore employ heterothermy greater than that recorded in any other large mammal, but water limitation, rather than high ambient temperature, seems to be the primary driver of this heterothermy.
Maturation of the angiotensin II cardiovascular response in the embryonic White Leghorn chicken (Gallus gallus)
Venue: Journal of Comparative Physiology B

Angiotensin II (Ang II) is an important regulator of cardiovascular function in adult vertebrates. Although its role in regulating the adult system has been extensively investigated, the cardiovascular response to Ang II in embryonic vertebrates is relatively unknown. We investigated the potential of Ang II as a regulator of cardiovascular function in embryonic chickens, which lack central nervous system control of cardiovascular function throughout the majority of incubation. The cardiovascular response to Ang II in embryonic chickens was investigated over the final 50% of their development. Ang II produced a dose-dependent increase in arterial pressure on each day of development studied, and the response increased in intensity as development progressed. The Ang II type-1 receptor nonspecific competitive peptide antagonist [Sar1 ile8] Ang II blocked the cardiovascular response to subsequent injections of Ang II on day 21 only. The embryonic pressure response to Ang II (hypertension only) differed from that of adult chickens, in which initial hypotension is followed by hypertension. The constant level of gene expression for the Ang II receptor, in conjunction with an increasing pressure response to the peptide, suggests that two Ang II receptor subtypes are present during chicken development. Collectively, the data indicate that Ang II plays an important role in the cardiovascular development of chickens; however, its role in maintaining basal function requires further study.
Localization dominance and the effect of frequency in the Mongolian Gerbil, Meriones unguiculatus
Venue: Journal of Comparative Physiology A

Due to its good low-frequency hearing, the Mongolian Gerbil (Meriones unguiculatus) has become a well-established animal model for human hearing. In humans, sound localization in reverberant environments is facilitated by the precedence effect, i.e., the perceptual suppression of spatial information carried by echoes. The current study addresses the question whether gerbils are a valid animal model for such complex spatial processing. Specifically, we quantify localization dominance, i.e., the fact that in the context of precedence, only the directional information of the sound which reaches the ear first dominates the perceived position of a sound source whereas directional information of the delayed echoes is suppressed. As localization dominance is known to be stimulus-dependent, we quantified the extent to which the spectral content of transient sounds affects localization dominance in the gerbil. The results reveal that gerbils show stable localization dominance across echo delays, well comparable to humans. Moreover, localization dominance systematically decreased with increasing center frequency, which has not been demonstrated in an animal before. These findings are consistent with an important contribution of peripheral-auditory processing to perceptual localization dominance. The data show that the gerbil is an excellent model to study the neural basis of complex spatial-auditory processing.
Pheromones in birds: myth or reality?
Venue: Journal of Comparative Physiology A

Birds are anosmic or at best microsmatic… This misbelief persisted until very recently and has strongly influenced the outcome of communication studies in birds, with olfaction remaining neglected as compared to acoustic and visual channels. However, there is now clear empirical evidence showing that olfaction is perfectly functional in birds and birds use olfactory information in a variety of ethological contexts. Although the existence of pheromones has never been formally demonstrated in this vertebrate class, different groups of birds, such as petrels, auklets and ducks have been shown to produce specific scents that could play a significant role in within-species social interactions. Behavioral experiments have indeed demonstrated that these odors influence the behavior of conspecifics. Additionally, in quail, deprivation of olfactory inputs decreases neuronal activation induced by sexual interactions with a female. It seems therefore well established that birds enjoy a functional sense of smell and a fast growing body of experimental evidence suggests that they use this channel of olfactory communication to control their social life. The unequivocal identification of an avian pheromone is, however, still ahead of us but there are now many exciting opportunities to unravel the behavioral and physiological particularities of chemical communication in birds.
Comparative analysis of crystallins and lipids from the lens of Antarctic toothfish and cow
Venue: Journal of Comparative Physiology B

Animal model systems of senile cataract and lens crystallin stability are essential to understand the complex nature of lens transparency. Our aim in this study was to assess the long-lived Antarctic toothfish Dissostichus mawsoni (Norman) as a model system to understand long-term lens clarity in terms of solubility changes that occur to crystallins. We compared the toothfish with the mammalian model cow lens, dissecting each species’ lens into a cortex and nuclear region. In addition to crystallin distribution, we also assayed fatty acid (FA) composition by negative ion electrospray ionization mass spectrometry (ESI-MS). The majority of toothfish lens crystallins from cortex (90.4%) were soluble, whereas only a third (31.8%) from the nucleus was soluble. Crystallin solubility analysis by SDS-PAGE and immunoblots revealed that relative proportions of crystallins in both soluble and urea-soluble fractions were similar within each species examined and in agreement with previous reports for bovine lens. From our data, we found that both toothfish and cow crystallins follow patterns of insolubility that mirror each animals lens composition with more γ crystallin aggregation seen in the toothfish lens nucleus than in cow. Toothfish lens lipids had a large amount of polyunsaturated fatty acids that were absent in cow resulting in an unsaturation index (IU) four-fold higher than that of cow. We identified a novel FA with a molecular mass of 267 mass units in the lens epithelial layer of the toothfish that accounted for well over 50% of the FA abundance. The unidentified lipid in the toothfish lens epithelia corresponds to either an odd-chain (17 carbons) FA or a furanoid. We conclude that long-lived fishes are likely good animal models of lens crystallin solubility and may model post-translational modifications and solubility changes better than short-lived animal models.