nils-herrmann/clean_scirepeval huggingface dataset:
Dynamics of acid–base metabolic compensation and hematological regulation interactions in response to CO2 challenges in embryos of the chicken (Gallus gallus)
Venue: Journal of Comparative Physiology B

CO2 exposure elicits multiple changes in the acid–base balance and hematology of avian embryos, but the time-specific, dose-dependent effects of graded increases in extrinsic CO2 in a normoxic environment are poorly understood. Consequently, we exposed day 15 chicken embryos to 1, 3, 5, 6 or 10 % CO2 in 20 % O2. We hypothesized that both the magnitude of hypercapnic respiratory acidosis and the resultant metabolic compensation within 24 h of exposure to <10 % CO2 are proportional to ambient CO2 concentration ([CO2]). We also predicted that regulation of hematological respiratory variables is graded according to [CO2]. Time-course (2, 6 and 24 h) changes were determined for acid–base disturbances and hematological respiratory variables; hematocrit (Hct), red blood cell concentration ([RBC]), hemoglobin concentration, mean corpuscular volume (MCV) and other mean corpuscular indices. Both the decrease in uncompensated pH, which indicates uncompensated respiratory acidosis, and the compensatory pH increase, a sign of metabolic compensation, increased with [CO2]. The partial metabolic compensation across all CO2 gas mixtures was ~17, 46 and 53 % compensation at 2, 6 and 24 h, respectively. Hematological responses were nearly identical across the entire range of [CO2], with Hct decreasing across the time course of CO2 exposure due to a decrease in MCV from 2 to 24 h and a decrease in [RBC] at 24 h. Even though hematological regulation was not graded, chicken embryos were able to compensate and survive exposure to <10 % CO2.
Multiple sources of celestial compass information in the Central Australian desert ant Melophorus bagoti
Venue: Journal of Comparative Physiology A

The Central Australian desert ant Melophorus bagoti is known to use celestial cues for compass orientation. We manipulated the available celestial cues for compass orientation for ants that had arrived at a feeder, were captured and then released at a distant test site that had no useful terrestrial panoramic cues. When tested in an enclosed transparent box that blocked some or most of the ultraviolet light, the ants were still well oriented homewards. The ants were again significantly oriented homewards when most of the ultraviolet light as well as the sun was blocked, or when the box was covered with tracing paper that eliminated the pattern of polarised light, although in the latter case, their headings were more scattered than in control (full-cue) conditions. When the position of the sun was reflected 180° by a mirror, the ants headed off in an intermediate direction between the dictates of the sun and the dictates of unrotated cues. We conclude that M. bagoti uses all available celestial compass cues, including the pattern of polarised light, the position of the sun, and spectral and intensity gradients. They average multiple cues in a weighted fashion when these cues conflict.
Ground reaction forces in vertically ascending beetles and corresponding activity of the claw retractor muscle on smooth and rough substrates
Venue: Journal of Comparative Physiology A

We measured ground reaction forces in fore–aft and normal directions of single hind and front legs in vertically ascending Sagra femorata beetles (Coleoptera, Chrysomelidae) on a smooth and a rough substrate. Simultaneously, we performed electromyographic recordings (EMGs) of the hind leg claw retractor muscle that partly controls the attachment structures. On both substrates, hind legs produced upward- as well as downward-directed forces during one stance phase. Forces were equivalent in both directions. Front legs generated only upward-directed forces. The main function of hind legs in ascending beetles in the second half of the stance thus probably prevented the animals from tilting away from the substrate. The EMGs of hind legs showed an early spike during stance with large amplitude. It was mostly followed by few additional spikes with large amplitude and in some cases of spikes with smaller amplitude distributed throughout the stance phase. We found significantly more spikes on the rough substrate than on the smooth one. This is probably due to the more important role of pretarsal claws than tarsal hairy attachment pads on the rough substrate or to the reduced adhesive forces on the rough substrate that have to be compensated by additional muscle activity.
Development and partial characterisation of an antiserum against apolipoprotein B of the short-finned eel, Anguilla australis
Venue: Journal of Comparative Physiology B

Despite its key role in transportation of triacylglycerides in blood, the distribution, localisation and molecular weight variants of apolipoprotein B (Apob) in teleost fish have essentially escaped study. To address this, a specific short-finned eel (Anguilla australis) Apob antiserum was produced by an immunised rabbit, purified and partially characterised. Localisation of Apob at both the mRNA (in situ hybridisation) and protein (immunohistochemistry) levels mirrored that of mammals; thus immunostaining was confined to the interstitial spaces of the liver and the vascular core of the intestinal villi. Immunostaining of proteins by Western blotting, followed by high-resolution LC–MS, indicated that peptide sequence coverage of Apob in low-density lipoproteins spanned the full-length protein. We conclude that only full-length Apob is produced by eels and that both liver and intestine are key sites for its synthesis.
Physiological basis of phototaxis to near-infrared light in Nephotettix cincticeps
Venue: Journal of Comparative Physiology A

In a previous study of the phototaxis of green rice leafhoppers, Nephotettix cincticeps (Hemiptera, Cicadellidae), we found positive responses to 735 nm light. Here, we investigated the mechanism underlying this sensitivity to near-infrared light. We first measured the action spectrum using a Y-maze with monochromatic lights from 480 to 740 nm. We thus found that the action spectrum peaks at 520 nm in the tested wavelength range, but that a significant effect is still observed at 740 nm, albeit with a sensitivity 5 log units lower than the peak. Second, we measured the spectral sensitivity of the eye, and found that the sensitivity in the long-wavelength region parallels the behaviorally determined action spectrum. We further identified mRNAs encoding opsins of ultraviolet, blue, and green-absorbing visual pigments, and localized the mRNAs in the ommatidia by in situ hybridization. The electrophysiology, molecular biology and the anatomy of the eye together indicate that the eyes of N. cincticeps do not contain true “red” receptors, but rather that the behavioral response to near-infrared light is mediated by the tail sensitivity of the green receptors in the long-wavelength region of the spectrum.
Temperature effects on metabolic rate and cardiorespiratory physiology of the spiny rock lobster (Jasus edwardsii) during rest, emersion and recovery
Venue: Journal of Comparative Physiology B

AbstractAlthough spiny rock lobster (Jasus edwardsii) is a wholly sub-littoral species, they show a considerable ability to survive prolonged emersion, a fact exploited during the commercial export of this species. Yet, despite this remarkable hardiness, basic information on how this species responds physiologically to emersion is somewhat lacking. Using flow-through respirometry and electrophysiological techniques, we identified that J. edwardsii undergoes marked physiological changes during rest, emersion and recovery over a broad range of temperatures (3.7–17.8 °C). Under resting conditions, routine metabolic rates (RMR) were 22.57 ± 2.39, 9.69 ± 0.55 and 8.09 ± 0.27 mL O2 h−1, average heart rates (Hr) were 54.72 ± 4.46, 37.68 ± 2.86 and 29.67 ± 0.59 BPM, and ventilation frequencies were 83.71 ± 5.86, 45.34 ± 2.91 and 41.62 ± 0.65 BPM at 15.0, 7.5 and 3.7 °C, respectively. Notably, the surgical implantation of electrodes elevated RMR compared with non-surgical treatments. In surgery and non-surgery groups, Q10 was calculated to be ca. 3.0. Upon emersion, rate of oxygen consumption and Hr decreased below resting rates in a temperature-dependent manner, but, along with rate of CO2 production, increased steadily during 24-h emersion. Ventilation frequencies upon emersion showed a contrasting response and increased significantly above resting rates. When returned to flow-through sea water for recovery, elevated respiration rates provided clear evidence of an O2 debt, and near-complete recovery was observed after 17 h at both 15.0 and 7.5 °C, but close to no debt was recovered at 3.7 °C. In addition, J. edwardsii was observed to undergo marked diurnal and periodic ventilation cycles, characterised by synchronous changes in RMR, Hr and ventilation frequency.
Sensitivity to hypercapnia and elimination of CO2 following diving in Steller sea lions (Eumetopias jubatus)
Venue: Journal of Comparative Physiology B

The diving ability of marine mammals is a function of how they use and store oxygen and the physiological control of ventilation, which is in turn dependent on the accumulation of CO2. To assess the influence of CO2 on physiological control of dive behaviour, we tested how increasing levels of inspired CO2 (hypercarbia) and decreasing inspired O2 (hypoxia) affected the diving metabolic rate, submergence times, and dive recovery times (time to replenish O2 stores and eliminate CO2) of freely diving Steller sea lions. We also measured changes in breathing frequency of diving and non-diving individuals. Our findings show that hypercarbia increased breathing frequency (as low as 2 % CO2), but did not affect metabolic rate, or the duration of dives or surface intervals (up to 3 % CO2). Changes in breathing rates indicated respiratory drive was altered by hypercarbia at rest, but blood CO2 levels remained below the threshold that would alter normal dive behaviour. It took the sea lions longer to remove accumulated CO2 than it did for them to replenish their O2 stores following dives (whether breathing ambient air, hypercarbia, or hypoxia). This difference between O2 and CO2 recovery times grew with increasing dive durations, increasing hypercarbia, and was greater for bout dives, suggesting there could be a build-up of CO2 load with repeated dives. Although we saw no evidence of CO2 limiting dive behaviour, the longer time required to remove CO2 may eventually exhibit control over the overall time they can spend in apnoea and overall foraging duration.
Ionic regulation in the Antarctic nematode Panagrolaimus davidi, measured using electron probe X-ray microanalysis
Venue: Journal of Comparative Physiology B

The element composition of the pseudocoelomic fluid of the Antarctic nematode Panagrolaimus davidi was analysed by electron probe X-ray microanalysis after absorbing the fluid into Sephadex G-25 beads, and after producing calibration curves by analysing various concentrations of elements of interest absorbed into beads. The nematodes maintain higher concentrations of sodium and potassium in their pseudocoelomic fluid than in the external medium but lower concentrations of magnesium and calcium. When external concentrations of specific ions were elevated there was evidence for the regulation of internal concentrations of sodium, potassium, magnesium and chlorine. The time course of changes in response to exposure to elevated levels of KCl shows an increase in internal concentrations of potassium and chlorine up to 2 h after exposure, followed by a decline. This is consistent with a model of ionic regulation proposed for Caenorhabditis elegans which suggests that high concentrations of ionic osmolytes are replaced by compatible organic osmolytes.
Physiological responses to short-term fasting among herbivorous, omnivorous, and carnivorous fishes
Venue: Journal of Comparative Physiology B

We explored the integrated role of dietary specialization and feeding periodicity on the response of the gastrointestinal tract of teleosts fishes to short-term (7–10 days) fasting and refeeding. Fasted and fed herbivorous grass carp (Ctenopharyngodon idella), omnivorous channel catfish (Ictalurus punctatus), and carnivorous largemouth bass (Micropterus salmoides) were compared for digestive organ masses, intestinal morphology, gastrointestinal pH, and the specific activities and total intestinal capacities of the intestinal hydrolases aminopeptidase (APN) and maltase and intestinal nutrient transporters. All three species experience intestinal hypertrophy with feeding as noted by significant increases in enterocyte dimensions. Of the three, only I. punctatus experienced a postprandial increase in intestinal length, and only C. idella experienced significant modulation of intestinal microvillus length. Feeding resulted in acidification of the stomachs of I. punctatus and M. salmoides. Predicted to exhibit a relatively modest set of postprandial responses because of their more frequent feeding habits, C. idella only experienced increases in APN and maltase activity with feeding and no significant regulation of nutrient uptake. Significant regulation of hydrolase activities and nutrient uptake were exhibited by I. punctatus and M. salmoides, with I. punctatus experiencing the most comprehensive set of responses. As predicted by food habits, there was an interspecific gradient in intestinal length and glucose uptake extending from longer intestines and greater glucose uptake for the herbivorous C. idella, intermediate lengths and glucose uptake for the omnivorous I. punctatus, and shorter intestines and reduced glucose uptake for the carnivorous M. salmoides. Among teleosts fishes, short episodes of fasting lead to significant alterations in intestinal form and function that are rapidly restored with feeding.
Pituitary control of branchial NCC, NKCC and Na+, K+-ATPase α-subunit gene expression in Nile tilapia, Oreochromis niloticus
Venue: Journal of Comparative Physiology B

This study investigated endocrine control of branchial ionoregulatory function in Nile tilapia (Oreochromis niloticus) by prolactin (Prl188 and Prl177), growth hormone (Gh) and cortisol. Branchial expression of Na+/Cl− cotransporter (ncc) and Na+/K+/2Cl− cotransporter (nkcc) genes were employed as specific markers for freshwater- and seawater-type ionocytes, respectively. We further investigated whether Prl, Gh and cortisol direct expression of two Na+, K+-ATPase (nka)-α1 subunit genes, denoted nka-α1a and nka-α1b. Tilapia transferred to fresh water following hypophysectomy failed to adequately activate gill ncc expression; ncc expression was subsequently restored by Prl replacement. Prl188 and Prl177 stimulated ncc expression in cultured gill filaments in a concentration-related manner, suggesting that ncc is regulated by Prl in a gill-autonomous fashion. Tilapia transferred to brackish water (23 ‰) following hypophysectomy exhibited a reduced capacity to up-regulate nka-α1b expression. However, Gh and cortisol failed to affect nka-α1b expression in vivo. Similarly, we found no clear effects of Gh or cortisol on nkcc expression both in vivo and in vitro. When considered with patterns previously described in euryhaline Mozambique tilapia (O. mossambicus), the current study suggests that ncc is a conserved target of Prl in tilapiine cichlids. In addition, we revealed contrasting dependencies upon the pituitary to direct nka-α1b expression in hyperosmotic environments between Nile and Mozambique tilapia.
Integration of polarization and chromatic cues in the insect sky compass
Venue: Journal of Comparative Physiology A

Animals relying on a celestial compass for spatial orientation may use the position of the sun, the chromatic or intensity gradient of the sky, the polarization pattern of the sky, or a combination of these cues as compass signals. Behavioral experiments in bees and ants, indeed, showed that direct sunlight and sky polarization play a role in sky compass orientation, but the relative importance of these cues are species-specific. Intracellular recordings from polarization-sensitive interneurons in the desert locust and monarch butterfly suggest that inputs from different eye regions, including polarized-light input through the dorsal rim area of the eye and chromatic/intensity gradient input from the main eye, are combined at the level of the medulla to create a robust compass signal. Conflicting input from the polarization and chromatic/intensity channel, resulting from eccentric receptive fields, is eliminated at the level of the anterior optic tubercle and central complex through internal compensation for changing solar elevations, which requires input from a circadian clock. Across several species, the central complex likely serves as an internal sky compass, combining E-vector information with other celestial cues. Descending neurons, likewise, respond both to zenithal polarization and to unpolarized cues in an azimuth-dependent way.
Neuroethology of male courtship in Drosophila: from the gene to behavior
Venue: Journal of Comparative Physiology A

Neurogenetic analyses in the fruit fly Drosophila melanogaster revealed that gendered behaviors, including courtship, are underpinned by sexually dimorphic neural circuitries, whose development is directed in a sex-specific manner by transcription factor genes, fruitless (fru) and doublesex (dsx), two core members composing the sex-determination cascade. Via chromatin modification the Fru proteins translated specifically in the male nervous system lead the fru-expressing neurons to take on the male fate, as manifested by their male-specific survival or male-specific neurite formations. One such male-specific neuron group, P1, was shown to be activated when the male taps the female abdomen. Moreover, when artificially activated, P1 neurons are sufficient to induce the entire repertoire of the male courtship ritual. These studies provide a conceptual framework for understanding how the genetic code for innate behavior can be embodied in the neuronal substrate.
Digestive enzymes of two brachyuran and two anomuran land crabs from Christmas Island, Indian Ocean
Venue: Journal of Comparative Physiology B

The digestive ability of four sympatric land crabs species (the gecarcinids, Gecarcoidea natalis and Discoplax celeste and the anomurans, Birgus latro and Coenobita perlatus) was examined by determining the activity of their digestive enzymes. The gecarcinids are detritivores that consume mainly leaf litter; the robber crab, B. latro, is an omnivore that preferentially consumes items high in lipid, carbohydrate and/or protein; C. perlatus is also an omnivore/detritivore. All species possess protease, lipase and amylase activity for hydrolysing ubiquitous protein, lipid and storage polysaccharides (glycogen and starch). Similarly all species possess enzymes such as N-acetyl-β-d-glucosaminidase, the cellulases, endo-β-1,4-glucanase and β-glucohydrolase and hemicellulases, lichenase and laminarinase for the respective hydrolysis of structural substrates chitin, cellulose and hemicelluloses, lichenan and laminarin. Except for the enzyme activities of C. perlatus, enzyme activity could not be correlated to dietary preference. Perhaps others factors such as olfactory and locomotor ability and metabolic status may determine the observed dietary preferences. The digestive fluid of C. perlatus possessed higher endo-β-1,4-glucanase, lichenase and laminarinase activities compared to that of the other species. Thus, C. perlatus may be efficient at digestion of cellulose and hemicellulose within plant material. Zymography indicated that the majority of protease, lipase, phosphatase, amylase, endo-β-1,4-glucanase, β-glucohydrolase and N-acetyl-β-d-glucosaminidase isozymes were common to all species, and hence were inherited from a common aquatic ancestor. Differences were observed for the phosphatase, lipase and endo-β-1,4-glucanase isozymes. These differences are discussed in relation to phylogeny and possible evolution to cope with the adoption of a terrestrial diet.
Transcript levels of class I GLUTs within individual tissues and the direct relationship between GLUT1 expression and glucose metabolism in Atlantic cod (Gadus morhua)
Venue: Journal of Comparative Physiology B

GLUTs 1–4 are sodium-independent facilitated glucose transporters and are considered to play a major role in glucose trafficking. The relative transcript levels of GLUTs 1–4 were determined in tissues of Atlantic cod (Gadus morhua). The distribution profile of GLUTs normalized to RNA is similar to mammals and with a few exceptions other fish. GLUT1 is ubiquitous, GLUT2 is relatively abundant in tissues that release glucose, GLUT3 expression is relatively strong in brain, and GLUT4 is relatively high in heart and muscle. The functionally significant level of transcript is presumably the level in the cell. Normalization of relative GLUT levels to tissue mass reveals there are extremely high levels of GLUT1 transcript in gas gland consistent with the high lactate production rates, GLUT3 is dominant in gill and head kidney as well as brain, and GLUT4 expression in gill is elevated relative to other tissues. Consideration of GLUTs within tissues reveals that GLUT1 is the dominant transcript in a group of tissues including gas gland, heart, white muscle, and RBCs. Brain, gill, and spleen display a co-dominance of GLUTs 1 and 3. There are relatively low levels of GLUT4 in most tissues, the highest being found in white muscle where GLUT4 accounts for only 12 % of the total transcript level. The apparent low level of GLUT4 transcript may reflect two tissues that were not included in the current study, red muscle and adipose tissue, due to their low abundance in Atlantic cod. The rate of glucose metabolism in isolated cells prepared from gas gland, heart, and RBCs was determined by tracking the rate of 3H2O production from [2-3H]-glucose. The steady-state rate of basal glycolysis in these three tissues correlates with relative transcript levels of GLUT1.
The comparison of sensitivity of motion sickness between retinal degeneration fast mice and normal mice
Venue: Journal of Comparative Physiology A

Recent studies report that a conflict between information from the visual system and vestibular system is one of the main reasons for induction of motion sickness (MS). We may be able to clarify the integration mechanism of visual and vestibular information using an animal model with a visual defect, the retinal degeneration fast (rdf) mouse, and the role of vestibular information in the pathogenesis of MS. The rdf mice and wild-type Kunming mice were subjected to rotary stimulation to induce MS. Conditioned taste anorexia to saccharin solution and behavior score were used to observe the differences in MS sensitivity between two types of mice. The decrease in intake of saccharin solution and the behavior score in rdf mice were greater than those in normal mice. After rotatory stimulation, the reduction of intake mass and the behavior score were greater in rdf mice compared to those of normal mice. The rdf mice were more sensitive to rotation than normal mice. We conclude that visual information plays a role in the pathogenesis of MS. Visual information and vestibular information impact each other and integrate through certain channels in the central nervous system in mice.