nils-herrmann/clean_scirepeval huggingface dataset:
Investigation of the presence and antinociceptive function of muscarinic acetylcholine receptors in the African naked mole-rat (Heterocephalus glaber)
Venue: Journal of Comparative Physiology A

The present study investigated the cholinergic system in the African naked mole-rat (Heterocephalus glaber) with focus on the muscarinic acetylcholine receptor subtypes M1 and M4. The protein sequences for the subtypes m1–5 of the naked mole-rat were compared to that of the house mouse (Mus musculus) using basic local alignment search tool (BLAST). The presence and function of M1 and M4 was investigated in vivo, using the formalin test with the muscarinic receptor agonists xanomeline and VU0152100. Spinal cord tissue from the naked mole-rat was used for receptor saturation binding studies with [3H]-N-methylscopolamine. The BLAST test revealed 95 % protein sequence homology showing the naked mole-rat to have the genetic potential to express all five muscarinic acetylcholine receptor subtypes. A significant reduction in pain behavior was demonstrated after administration of 8.4 mg/kg in the formalin test. Administration of 50 mg/kg VU0152100 resulted in a non-significant tendency towards antinociception. The antinociceptive effects were reversed by the muscarinic acetylcholine receptor antagonist atropine. Binding studies indicated presence of muscarinic acetylcholine receptors with a radioligand affinity comparable to that reported in mice. In conclusion, muscarinic acetylcholine receptor subtypes are present in the naked mole-rat and contribute to antinociception in the naked mole-rat.
Identification and characterisation of hemocyanin of the fish louse Argulus (Crustacea: Branchiura)
Venue: Journal of Comparative Physiology B

Hemocyanin transports oxygen in the hemolymph of many arthropod species. Within the crustaceans, this copper-containing protein was thought to be restricted to Malacostraca, while other crustacean classes were assumed to employ hemoglobin or lack any respiratory protein. Only recently it has become evident that hemocyanins also occur in Remipedia and Ostracoda. Here we report for the first time the identification and characterisation of hemocyanin in the fish louse Argulus, which belongs to the class of Branchiura. This finding indicates that hemocyanin was the principal oxygen carrier in the stem lineage of the pancrustaceans, but has been lost independently multiple times in crustacean taxa. We obtained the full-length cDNA sequences of two hemocyanin subunits of Argulus foliaceus by a combination of RT-PCR, RACE and Illumina sequencing of the transcriptome. In addition, one full-length and one partial cDNA sequence were derived from the transcriptome data of Argulus siamensis. Western blot analysis confirmed the presence of at least two hemocyanin subunits in A. foliaceus, which are expressed at the mRNA level at a 1:3.5 ratio. The addition to the branchiuran hemocyanin subunits to a multiple sequence alignment of arthropod, hemocyanins improved the phylogenetic resolution within the pancrustacean hemocyanins. Malacostracan, ostracod and branchiuran hemocyanins are distinct from the hexapod and remipede hemocyanins, reinforcing the hypothesis of a close relationship of Remipedia and Hexapoda. Notably, the ostracod hemocyanins are paraphyletic with respect to the branchiuran hemocyanins, indicating ancient divergence and differential loss of distinct subunit types.
Landscape vision and zonal orientation in the Equatorial sandhopper Talorchestia martensii
Venue: Journal of Comparative Physiology A

We investigate the role of the landscape in the zonal recovery of the Equatorial sandhopper Talorchestia martensii Weber. It is known that this species uses the sun and the magnetic compasses to return to the belt of damp sand of the beach following the shortest route (the sea-land axis). However, the sun is not always easy to use at Equatorial latitudes because of astronomical reasons (its zenithal culmination and its hourly azimuthal speed) at least during the central time of the day (around noon) and close to the equinox. Our experiments were performed in Kenya, during the equinoctial period. We tested adult individuals, belonging to Malindi (Kenya) population, in a confined environment with and without the vision of the landscape of their home beach and with the vision of the prominent landscape of a different-orientated shore (Temple Point). Releases were carried out with either natural or zeroed magnetic field. Results clearly show the importance of the landscape as an orienting factor mainly during the central hours of the day when it seems to assume a greater importance than magnetic cues.
Variability in the temporal parameters in the song of the Bengalese finch (Lonchura striata var. domestica)
Venue: Journal of Comparative Physiology A

Birdsong provides a unique model for studying the control mechanisms of complex sequential behaviors. The present study aimed to demonstrate that multiple factors affect temporal control in the song production. We analyzed the song of Bengalese finches in various time ranges to address factors that affected the duration of acoustic elements (notes) and silent intervals (gaps). The gaps showed more jitter across song renditions than did notes. Gaps had longer duration in branching points of song sequence than in stereotypic transitions, and the duration of a gap was correlated with the duration of the note that preceded the gap. When looking at the variation among song renditions, we found notable factors in three time ranges: within-day drift, within-bout changes, and local jitter. Note durations shortened over time from morning to evening. Within each song bout note durations lengthened as singing progressed, while gap durations lengthened only during the late part of song bout. Further analysis after removing these drift factors confirmed that the jitter remained in local song sequences. These results suggest distinct sources of temporal variability exist at multiple levels on the basis of this note–gap relationship, and that song comprised a mixture of these sources.
Occluding junctions of invertebrate epithelia
Venue: Journal of Comparative Physiology B

Invertebrate diversity and architecture is immense. This is achieved by the organization and function of four tissue types found in most metazoan phyla—epithelial, connective, muscle and nervous tissue. Epithelial tissue is found in all extant animals (parazoan and metazoan alike). Epithelial cells form cellular sheets that cover internal or external surfaces and regulate the passage of material between separated compartments. The transepithelial movement of biological material between compartments can occur across the transcellular pathway (i.e. across cells) or the paracellular pathway (i.e. between cells) and the latter is regulated by occluding junctions that typically link cells in a subapical domain. In this review, information on occluding junctions of invertebrate epithelia is consolidated and discussed in the context of morphology, ultrastructure and physiology. In addition, an overview of what is currently known about invertebrate occluding junction proteins and their role in maintaining the integrity of invertebrate epithelia and regulating the barrier properties of these tissues is presented.
Phosphorylation increases the catalytic activity of rainbow trout gill cytosolic carbonic anhydrase
Venue: Journal of Comparative Physiology B

Cytoplasmic carbonic anhydrase (CAc) in the gill of teleost fish contributes to ionic regulation and acid–base balance by catalyzing the reversible reaction of CO2 and water, CO2 + H2O ↔ H+ + HCO3−. Regulation of CAc abundance and activity therefore is expected to fine-tune responses to ionic or acid–base challenges. The present study investigated the potential for gill CAc of rainbow trout, Oncorhynchusmykiss (tCAc), to undergo reversible phosphorylation. The activity of tCAc was approximately doubled by phosphorylation achieved through in vitro stimulation of endogenous protein kinases; kinase stimulation doubled phospho-threonine content from that observed in tCAc isolated under conditions where both kinases and protein phosphatases were inhibited. In vitro incubation to preferentially stimulate specific kinases implicated protein kinase G (PKG) in mediating the increase in tCAc activity. The kinetic parameters of turnover number (kcat) and substrate affinity (Km) were similarly affected by stimulation of either kinase or phosphatase action. However, phosphorylation via kinase stimulation significantly increased the efficiency of tCAc (Vmax/Km), and this factor may have contributed to the elevation of tCAc activity. In addition, phosphorylation of tCAc by kinase stimulation significantly increased the inhibition constant (Ki) for acetazolamide. These results demonstrate that tCAc is subject to reversible phosphorylation; future work should focus on identifying the physiological situation(s) in which phosphorylation of trout branchial CAc occurs.
Active auditory mechanics in female black-horned tree crickets (Oecanthus nigricornis)
Venue: Journal of Comparative Physiology A

The acoustic signalling behaviour of many tree cricket species is easily observed and has been well described. Very little is known, however, about the receivers in these communication loops. The exception to this is a single Indian species (Oecanthus henryi) which employs active auditory mechanics to enhance female sensitivity to quiet sounds at male calling frequencies. In most species, male calls have been described, but whether or not sender–receiver matching is present is uncertain. Here we investigate auditory mechanics in females of the North American black-horned tree cricket (Oecanthus nigricornis). The response of the anterior tympanal membrane is nonlinear, exhibiting a lack of tuning at high amplitudes (60 dB and above) but as stimulus amplitude decreases, the membrane becomes tuned to around 4.3 kHz. The tuning of the membrane falls within the frequency range of male calls indicating sender–receiver matching at low amplitudes, which could aid localisation of the highly directional calls of males. The extent of active auditory mechanics in tympanal insects is not yet known, but this paper provides an indication that this may indeed be widespread in at least the Oecanthinae.
Respiratory plasticity is insufficient to alleviate blood acid–base disturbances after acclimation to ocean acidification in the estuarine red drum, Sciaenops ocellatus
Venue: Journal of Comparative Physiology B

The changes in ocean chemistry stemming from anthropogenic CO2 release—termed ocean acidification (OA)—are predicted to have wide-ranging effects on fish and ultimately threaten global populations. The ability of fish to adapt to environmental change is currently unknown, but phenotypic plasticity has been highlighted as a crucial factor in determining species resilience. Here we show that red drum, a long-lived estuarine-dependent fish species native to the Gulf of Mexico, exhibit respiratory plasticity that increases CO2 excretion capacity when acclimated to OA conditions. Specifically, fish exposed to 14 days of 1000 µatm CO2 had a 32 % reduction in branchial diffusion distance and increased expression of two putative CO2 channel proteins—rhag and rhcg1. No changes were observed in the erythrocyte CO2 transport pathways. Surprisingly, no significant changes in blood chemistry were observed between acclimated and acutely challenged animals; however, a non-significant 30 % drop in the magnitude of plasma $$C_{{{\text{CO}}_ }}$$CCO2 elevation was observed. Reduced diffusion distance also comes with the cost of increased diffusive water loss, which would require greater osmoregulatory investment by the animal. OA exposure induced increased gill Na+, K+ ATPase activity and intestinal nkcc2 expression, supporting both the presumed osmotic stress and increased osmoregulatory investment. However, no differences in standard metabolic rate, maximum metabolic rate or aerobic scope were detected between control and OA acclimated individuals. Similarly, no differences in critical swim speed were detected between groups, suggesting the energetic cost related to respiratory plasticity is negligible against background metabolism. The current study demonstrated that red drum exhibit respiratory plasticity with only mild physiological trade-offs; however, this plasticity is insufficient to fully offset the OA-induced acid–base disturbance and as such is unlikely to impact species resilience.
Von Willebrand factor is reversibly decreased during torpor in 13-lined ground squirrels
Venue: Journal of Comparative Physiology B

During torpor in a hibernating mammal, decreased blood flow increases the risk of blood clots such as deep vein thrombi (DVT). In other animal models platelets, neutrophils, monocytes and von Willebrand factor (VWF) have been found in DVT. Previous research has shown that hibernating mammals decrease their levels of platelets and clotting factors VIII (FVIII) and IX (FIX), increasing both bleeding time and activated partial thromboplastin time. In this study, FVIII, FIX and VWF activities and mRNA levels were measured in torpid and non-hibernating ground squirrels (Ictidomys tridecemlineatus). Here, we show that VWF high molecular weight multimers, collagen-binding activity, lung mRNA and promoter activity decrease during torpor. The VWF multimers reappear in plasma within 2 h of arousal in the spring. Similarly, FIX activity and liver mRNA both dropped threefold during torpor. In contrast, FVIII liver mRNA levels increased twofold while its activity dropped threefold, consistent with a post-transcriptional decrease in FVIII stability in the plasma due to decreased VWF levels. Finally, both neutrophils and monocytes are decreased eightfold during torpor which could slow the formation of DVT. In addition to providing insight in how blood clotting can be regulated to allow mammals to survive in extreme environments, hibernating ground squirrels provide an interesting model for studying.
Warmer temperatures reduce the costs of inducible defences in the marine toad, Rhinella marinus
Venue: Journal of Comparative Physiology B

Many of the far-reaching impacts of climate change on ecosystem function will be due to alterations in species interactions. However, our understanding of the effects of temperature on the dynamics of interactions between species is largely inadequate. Inducible defences persist in prey populations because defensive traits increase survival in the presence of predators but are costly when they are absent. Large-scale changes in the thermal climate are likely to alter the costs or benefits of these defences for ectotherms, whose physiological processes are driven by environmental temperature. A shift in costs of defensive traits would affect not only predator–prey interactions, but also the strength of selection for inducible defences in natural populations. We investigate the effect of temperature on the costs of behavioural defences in larvae of the marine toad, Rhinella marinus. Larvae were reared in the presence or absence of predator cues at both 25 and 30 °C. When exposed to predation cues, larvae reduced activity and spent less time feeding. Exposure to predation cues also reduced metabolic rate, presumably as a by-product of reducing activity levels. Larvae exposed to predation cues also grew more slowly, were smaller at metamorphosis and were poorer jumpers after metamorphosis—three traits associated with fitness in post-metamorphic anurans. We found that the costs of behavioural defences, in terms of larval growth, post-metamorphic size and jumping performance, were exacerbated at cooler temperatures. The thermal sensitivity of costs associated with defensive traits may explain geographic variation in plasticity of defensive traits in other species and suggests that changes in environmental temperature associated with climate change may affect predator–prey interactions in subtle ways not previously considered.
Gymnocypris przewalskii decreases cytosolic carbonic anhydrase expression to compensate for respiratory alkalosis and osmoregulation in the saline-alkaline lake Qinghai
Venue: Journal of Comparative Physiology B

Naked carp (Gymnocypris przewalskii), endemic to the saline-alkaline Lake Qinghai, have the capacity to tolerate combined high salinity and alkalinity, but migrate to spawn in freshwater rivers each year. In this study, the full-length cDNA of the cytosolic carbonic anhydrase c isoform of G. przewalskii (GpCAc) was amplified and sequenced; mRNA levels and enzyme activity of GpCAc and blood chemistry were evaluated to understand the compensatory responses as the naked carp returned to the saline-alkaline lake after spawning. We found that GpCAc had a total length of 1400 bp and encodes a peptide of 260 amino acids. Comparison of the deduced amino acid sequences and phylogenetic analysis showed that GpCAc was a member of the cytosolic carbonic anhydrase II-like c family. Cytosolic-carbonic-anhydrase-c-specific primers were used to analyze the tissue distribution of GpCAc mRNA expression. Expression of GpCAc mRNA was found in brain, gill, liver, kidney, gut, and muscle tissues, but primarily in the gill and posterior kidney; however, none was evident in red blood cells. Transferring fish from river water to lake water resulted in a respiratory alkalosis, osmolality, and ion rise in the blood, as well as significant decreases in the expression and enzyme activity of GpCAc in both the gill and kidney within 96 h. These results indicate that GpCAc may play an important role in the acclimation to both high salinity and carbonate alkalinity. Specifically, G. przewalskii decreases cytosolic carbonic anhydrase c expression to compensate for a respiratory alkalosis and to aid in osmoregulation during the transition from river to saline-alkaline lake.
Short- and long-wavelength-sensitive opsins are involved in photoreception both in the retina and throughout the central nervous system of crayfish
Venue: Journal of Comparative Physiology A

Crayfish have two classes of photoreceptors in the retinas of their reflecting superposition eyes. Long-wavelength-sensitive photoreceptors, comprised of microvilli from R1–7 cells, make up the main rhabdoms. Eighth retinular cells, located distal to the main rhabdoms, house short-wavelength-sensitive photoreceptors. While the opsin involved in long-wavelength sensitivity has long been known, we present the first description of the short-wavelength-sensitive opsin in the retina of the red swamp crayfish, Procambarus clarkii. The expression patterns of these SWS and LWS opsin proteins in the retina are consistent with the previously described locations of SWS and LWS receptors. Crayfish also have a well-characterized extraocular photoreceptor, called the caudal photoreceptor, located in the sixth abdominal ganglion. To search for retinal opsins in the caudal photoreceptor (and elsewhere in the CNS), we used RT-PCR and immunohistochemical labeling. We found both SWS and LWS opsin transcripts not only in the sixth abdominal ganglion, but also in all ganglia of the nerve cord. Immunolabeling shows that both opsins are expressed in nerve fibers that extend from the brain through the entire length of the CNS. Thus, the same two photopigments are used both for vision in the retina and for extraocular functions throughout the CNS of crayfish.
Temperature-dependence of L-type Ca2+ current in ventricular cardiomyocytes of the Alaska blackfish (Dallia pectoralis)
Venue: Journal of Comparative Physiology B

To lend insight into the overwintering strategy of the Alaska blackfish (Dallia pectoralis), we acclimated fish to 15 or 5 °C and then utilized whole-cell patch clamp to characterize the effects of thermal acclimation and acute temperature change on the density and kinetics of ventricular L-type Ca2+ current (ICa). Peak ICa density at 5 °C (−1.1 ± 0.1 pA pF−1) was 1/8th that at 15 °C (−8.8 ± 0.6 pA pF−1). However, alterations of the Ca2+- and voltage-dependent inactivation properties of L-type Ca2+ channels partially compensated against the decrease. The time constant tau (τ) for the kinetics of inactivation of ICa was ~4.5 times greater at 5 °C than at 15 °C, and the voltage for half-maximal inactivation was shifted from −23.3 ± 1.0 mV at 15 °C to −19.8 ± 1.2 mV at 5 °C. These modifications increase the open probability of the channel and culminate in an approximate doubling of the L-type Ca2+ window current, which contributes to approximately 15 % of the maximal Ca2+ conductance at 5 °C. Consequently, the charge density of ICa (QCa) and the total Ca2+ transferred through the L-type Ca2+ channels (Δ[Ca2+]) were not as severely reduced at 5 °C as compared to peak ICa density. In combination, the results suggest that while the Alaska blackfish substantially down-regulates ICa with acclimation to low temperature, there is sufficient compensation in the kinetics of the L-type Ca2+ channel to support the level of cardiac performance required for the fish to remain active throughout the winter.
Pharmacological identification of cholinergic receptor subtypes on Drosophila melanogaster larval heart
Venue: Journal of Comparative Physiology B

Drosophila melanogaster heart is a popular model in
 which to study cardiac physiology and development. Progress has been made in understanding the role of endogenous compounds in regulating cardiac function in this model. It is well characterized that common neurotransmitters act on many peripheral and non-neuronal tissues as they flow through the hemolymph of insects. Many of these neuromodulators, including acetylcholine (ACh), have been shown to act directly on the D. melanogaster larval heart. ACh is a primary neurotransmitter in the central nervous system (CNS) of vertebrates and at the neuromuscular junctions on skeletal and cardiac tissue. In insects, ACh is the primary excitatory neurotransmitter of sensory neurons and is also prominent in the CNS. A full understanding regarding the regulation of the Drosophila cardiac physiology by the cholinergic system remains poorly understood. Here we use semi-intact D. melanogaster larvae to study the pharmacological profile of cholinergic receptor subtypes, nicotinic acetylcholine receptors (nAChRs) and muscarinic acetylcholine receptors (mAChRs), in modulating heart rate (HR). Cholinergic receptor agonists, nicotine and muscarine both increase HR, while nAChR agonist clothianidin exhibits no significant effect when exposed to an open preparation at concentrations as low as 100 nM. In addition, both nAChR and mAChR antagonists increase HR as well but also display capabilities of blocking agonist actions. These results provide evidence that both of these receptor subtypes display functional significance in regulating the larval heart’s pacemaker activity.