nils-herrmann/clean_scirepeval huggingface dataset:
Color vision in insects: insights from Drosophila
Venue: Journal of Comparative Physiology A

Color vision is an important sensory capability that enhances the detection of contrast in retinal images. Monochromatic animals exclusively detect temporal and spatial changes in luminance, whereas two or more types of photoreceptors and neuronal circuitries for the comparison of their responses enable animals to differentiate spectral information independent of intensity. Much of what we know about the cellular and physiological mechanisms underlying color vision comes from research on vertebrates including primates. In insects, many important discoveries have been made, but direct insights into the physiology and circuit implementation of color vision are still limited. Recent advances in Drosophila systems neuroscience suggest that a complete insect color vision circuitry, from photoreceptors to behavior, including all elements and computations, can be revealed in future. Here, we review fundamental concepts in color vision alongside our current understanding of the neuronal basis of color vision in Drosophila, including side views to selected other insects.
Contrast sensitivity and visual acuity of Queensland fruit flies (Bactrocera tryoni)
Venue: Journal of Comparative Physiology A

This study examines the visual acuity of Queensland fruit flies (Bactrocera tryoni) by analysing their turning responses to an immersive visual stimulus consisting of a pattern of vertical stripes presented at various angular periods and rotational rates. The results infer that these flies possess an interommatidial angle of approximately 2∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${2}^{\circ }$$\end{document}, and an ommatidial acceptance angle of approximately 1.72∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${1.72}^{\circ }$$\end{document}. This suggests that the visual acuity of Queensland fruit flies is substantially better than that of the classical vinegar fly (Drosophila melanogaster), and is comparable to those of the housefly (Musca domestica) and the honeybee (Apis mellifera). The contrast sensitivity of Queensland fruit flies is comparable to that of the housefly.
Distribution and physiological effect of enterin neuropeptides in the olfactory centers of the terrestrial slug Limax
Venue: Journal of Comparative Physiology A

In gastropods, the function of neuropeptides has been studied primarily in the peripheral motor systems. Their functional roles in the central nervous system have received less attention. The procerebrum, the secondary olfactory center of the terrestrial slug Limax, consists of several hundred thousand interneurons, and plays a pivotal role in olfactory learning and memory. In the present study, we found that enterin, known as a myoactive peptide functioning in the enteric and vascular system of Aplysia, is expressed in the procerebrum of Limax. These enterin-expressing neurons primarily make projections within the cell mass layer of the procerebrum. The oscillatory frequency of the local field potential in the procerebrum was reduced by an exogenous application of enterin. The local field potential oscillation in the tentacular ganglion, the primary olfactory center, was also modulated by enterin. Whole-cell patch-clamp recordings revealed that the modulatory effect in the procerebrum was due to the inhibitory effect of enterin on the bursting neurons, which function as the kernels determining the oscillatory activity of the procerebrum. Our results revealed the novel role of the myoactive neuropeptide enterin in the higher olfactory function in terrestrial gastropods.
The effect of temperature and meal size on the aerobic scope and specific dynamic action of two temperate New Zealand finfish Chrysophrys auratus and Aldrichetta forsteri
Venue: Journal of Comparative Physiology B

Shallow coastal and estuarine habitats function as nurseries for many juvenile fish. In this comparative study, metabolic profiles of two New Zealand finfish, snapper (Chrysophrys auratus) and yellow-eyed mullet—YEM (Aldrichetta forsteri) that as juveniles share the same temperate coastal environments, were examined. Metabolic parameters (routine and maximum metabolic rates, and specific dynamic action—SDA) were investigated at a set of temperatures (13, 17, 21 °C) within the range juveniles both species experience annually. SDA was also determined for a range of different feed rations to investigate the effects of meal size on postprandial metabolic response. Temperature was a strong modulator of snapper and YEM metabolic profile (routine and maximum metabolic rates, and absolute and factorial aerobic scope). Metabolic rates increased with temperature in both species as did absolute scope in YEM, though for snapper, it was only greater at the highest temperature. Factorial scope behaved in the same fashion for the two species, being greatest at 13 °C. Both absolute and factorial scope were ~ twofold greater in YEM than in snapper across the entire temperature range. Temperature also affected SDA response in snapper, while in YEM, SDA parameters were largely unaffected when temperature increased from 17 to 21 °C. Snapper were able to consume a large range of meal sizes (0.5–3.0% body mass—BM) with meal sizes > 1% BM having a pronounced effect on numerous SDA parameters, whereas mullet appeared to consume more limited ration sizes (≤ 1.0% BM). In both species, rations ≤ 1% BM produced similar changes in SDA parameters identifying comparable digestive bio-energetics. Overall, our metabolic characterisations demonstrate that both species can adjust to the variable temperate environmental temperatures and manage the energetic costs of digestion and feed assimilation. Yet, despite these general similarities, YEM’s greater aerobic scope may point to better physiological adaptation to the highly variable temperate coastal environment than were observed in snapper.
Visual motion sensitivity in descending neurons in the hoverfly
Venue: Journal of Comparative Physiology A

Many animals use motion vision information to control dynamic behaviors. For example, flying insects must decide whether to pursue a prey or not, to avoid a predator, to maintain their current flight trajectory, or to land. The neural mechanisms underlying the computation of visual motion have been particularly well investigated in the fly optic lobes. However, the descending neurons, which connect the optic lobes with the motor command centers of the ventral nerve cord, remain less studied. To address this deficiency, we describe motion vision sensitive descending neurons in the hoverfly Eristalis tenax . We describe how the neurons can be identified based on their receptive field properties, and how they respond to moving targets, looming stimuli and to widefield optic flow. We discuss their similarities with previously published visual neurons, in the optic lobes and ventral nerve cord, and suggest that they can be classified as target-selective, looming sensitive and optic flow sensitive, based on these similarities. Our results highlight the importance of using several visual stimuli as the neurons can rarely be identified based on only one response characteristic. In addition, they provide an understanding of the neurophysiology of visual neurons that are likely to affect behavior.
Evolution of olfactory circuits in insects
Venue: Journal of Comparative Physiology A

Recent years have seen an explosion of interest in the evolution of neural circuits. Comparison of animals from different families, orders, and phyla reveals fascinating variation in brain morphology, circuit structure, and neural cell types. However, it can be difficult to connect the complex changes that occur across long evolutionary distances to behavior. Luckily, these changes accumulate through processes that should also be observable in recent time, making more tractable comparisons of closely related species relevant and complementary. Here, we review several decades of research on the evolution of insect olfactory circuits across short evolutionary time scales. We describe two well-studied systems, Drosophila sechellia flies and Heliothis moths, in detailed case studies. We then move through key types of circuit evolution, cataloging examples from other insects and looking for general patterns. The literature is dominated by changes in sensory neuron number and tuning at the periphery—often enhancing neural response to odorants with new ecological or social relevance. However, changes in the way olfactory information is processed by central circuits is clearly important in a few cases, and we suspect the development of genetic tools in non-model species will reveal a broad role for central circuit evolution. Moving forward, such tools should also be used to rigorously test causal links between brain evolution and behavior.
Transport of maternal transthyretin to the fetus in the viviparous teleost Neoditrema ransonnetii (Perciformes, Embiotocidae)
Venue: Journal of Comparative Physiology B

The molecular basis of viviparity in non-mammalian species has not been widely studied. Neoditrema ransonnetii, a surfperch, is a matrotrophic teleost whose fetuses grow by ovarian cavity fluid (OCF) ingestion and by nutrient absorption via their enlarged hindgut. We performed a proteomics analysis of N. ransonnetii plasma protein and found proteins specific to pregnant females; one of these was identified as transthyretin (TTR), a thyroid hormone distributor protein. We synthesized recombinant protein rNrTTR and raised an antibody, anti-rNrTTR, against it. Semi-quantitative analysis by western blotting using the antibody demonstrated that plasma TTR levels were significantly greater in pregnant fish than in non-pregnant fish. OCF and fetal plasma also contained high TTR levels. Immunohistochemical staining showed that large amounts of maternal TTR were taken up by fetal intestinal epithelial cells. These results indicate that maternal TTR is secreted into OCF and taken up by fetal enterocytes, presumably to deliver thyroid hormones to developing fetuses.
Salinity-dependent expression of ncc2 in opercular epithelium and gill of mummichog (Fundulus heteroclitus)
Venue: Journal of Comparative Physiology B

Mummichogs (Fundulus heteroclitus) can tolerate abrupt changes in environmental salinity because of their ability to rapidly adjust the activities of ionocytes in branchial and opercular epithelia. In turn, the concerted expression of sub-cellular effectors of ion transport underlies adaptive responses to fluctuating salinities. Exposure to seawater (SW) stimulates the expression of Na+/K+/2Cl− cotransporter 1 (nkcc1) and cystic fibrosis transmembrane regulator (cftr) mRNAs in support of ion extrusion by SW-type ionocytes. Given the incomplete understanding of how freshwater (FW)-type ionocytes actually operate in mummichogs, the transcriptional responses essential for ion absorption in FW environments remain unresolved. In a subset of species, a ‘fish-specific’ Na+/Cl− cotransporter denoted Ncc2 (Slc12a10) is responsible for the uptake of Na+ and Cl− across the apical surface of FW-type ionocytes. In the current study, we identified an ncc2 transcript that is highly expressed in gill filaments and opercular epithelium of FW-acclimated mummichogs. Within 1 day of transfer from SW to FW, ncc2 levels in both tissues increased in parallel with reductions in nkcc1 and cftr. Conversely, mummichogs transferred from FW to SW exhibited marked reductions in ncc2 concurrent with increases in nkcc1 and cftr. Immunohistochemical analyses employing a homologous antibody revealed apical Ncc2-immunoreactivity in Na+/K+-ATPase-immunoreactive ionocytes of FW-acclimated animals. Our combined observations suggest that Ncc2/ncc2-expressing ionocytes support the capacity of mummichogs to inhabit FW environments.
In vitro characterisation of calcium influx across skin and gut epithelia of the Pacific hagfish, Eptatretus stoutii
Venue: Journal of Comparative Physiology B

Although hagfishes osmoconform, concentrations of calcium in their extracellular fluids are maintained at levels lower than those of seawater. Ultimately, calcium homeostasis is a product of relative rates of influx and efflux into the animal, but little is known regarding these processes in hagfish. Using in vitro approaches, calcium influx across gut and skin epithelia of the Pacific hagfish, Eptatretus stoutii, was characterised. Analysis of concentration-dependent kinetics showed that accumulation into skin tissue was linear at mucosal calcium concentrations up to 10 mM. However, movement into the serosal compartment was saturable, with a maximal transport rate of 59 nmol cm−2 h−1 and an affinity (substrate concentration to give half maximal transport rate) of 1139 µM. Calcium accumulation into gut tissue and uptake into the gut serosal compartment was also saturable, with maximal transport rates of 5.1 and 2.8 nmol cm−2 h−1, and affinities of 6417 and 3327 µM, respectively. A strong correlation between epidermal and intestinal calcium tissue uptake was noted in assays where tissues were taken from the same individual. Intestinal calcium influx was inhibited by nickel, but not significantly affected by other putative inorganic (lanthanum, zinc) or organic (diltiazem, verapamil) transport blockers. Inhibitors had no effect on skin calcium handling. These data indicate that both gut and skin epithelia mediate calcium influx in hagfishes, albeit via distinct mechanisms and with differences in responsiveness to potential modifying factors.
Growing up gator: a proteomic perspective on cardiac maturation in an oviparous reptile, the American alligator (Alligator mississippiensis)
Venue: Journal of Comparative Physiology B

We recently described lasting changes in the cardiac proteome of American alligators (Alligator mississippiensis) reared under hypoxic conditions, that resemble what embryos encounter in natural nests. While these changes were consistent with functional differences in cardiac performance induced by developmental hypoxia, the magnitude of this response was dwarfed by a much greater effect of development alone (76% of the total differentially abundant proteins). This means that substantial differences in relative steady-state protein expression occur in the hearts of alligators as they mature from egg-bound embryos to 2-year-old juveniles, and this developmental program is largely resistant to variation in nest conditions. We therefore performed functional enrichment analysis of the 412 DA proteins that were altered by development but not hypoxia, to gain insight into the mechanisms of cardiac maturation in this ectotherm. We found that the cardiac proteome of alligators at 90% of embryonic development retained a considerable capacity for transcription and translation, suggesting the heart was still primarily invested in growth even as the animal approached hatching. By contrast, the cardiac proteome of 2-year-old juveniles was weighted towards structural and energetic processes typical of a working heart. We discuss our results in the context of differences in cardiac development between ectothermic and endothermic oviparous vertebrates, and argue that the robust developmental program of the alligator heart reflects a slow-paced ontogeny, unburdened by the requirement to support the elevated peripheral oxygen demand typical of endothermic animals from a young age.
Reverse translation: effects of acclimation temperature and acute temperature challenges on oxygen consumption, diffusive water flux, net sodium loss rates, Q10 values and mass scaling coefficients in the rainbow trout (Oncorhynchus mykiss)
Venue: Journal of Comparative Physiology B

Our understanding is limited on how fish adjust the effective permeability of their branchial epithelium to ions and water while altering O2 uptake rate (MO2) with acute and chronic changes in temperature. We investigated the effects of acclimation temperature (8 °C, 13 °C and 18 °C) and acute temperature challenges [acute rise (acclimated at 8 °C, measured at 13 °C and 18 °C), acute drop (acclimated at 18 °C, measured at 8 °C and 13 °C) and intermediate (acclimated at 13 °C, measured at 8 °C and 18 °C)] on routine MO2, diffusive water flux, and net sodium loss rates in 24-h fasted rainbow trout (Oncorhynchus mykiss). In the temperature challenge tests, measurements were made during the first hour. In acclimated trout at all temperatures, allometric mass scaling coefficients were much higher for diffusive water flux than for MO2. Furthermore, the diffusive water flux rate was more responsive (overall Q10 = 2.75) compared to MO2 (Q10 = 1.80) over the 8–18 °C range, and for both, Q10 values were greater at 8–13 °C than at 13–18 °C. The net Na+ flux rates were highly sensitive to acclimation temperature with an overall Q10 of 3.01 for 8–18 °C. In contrast, very different patterns occurred in trout subjected to acute temperature challenges. The net Na+ flux rate was temperature-insensitive with a Q10 around 1.0. Both MO2 and diffusive water flux rates exhibited lower Q10 values than for the acclimated rates in response to either acute increases or decreases in temperature. These results fit Pattern 5 of Precht (undercompensation, reverse effect) and more precisely Pattern IIB of Prosser (reverse translation). These inverse compensatory patterns suggest that trout do not alter their rates very much when undergoing acute thermal challenges (diurnal fluctuations, migration through the thermocline). The greater changes seen with acclimation may be adaptive to long-term seasonal changes in temperature. We discuss the roles of aquaporins, spontaneous activity, and recent feeding in these responses.
Neurons and astrocytes of the chicken hypothalamus directly respond to lipopolysaccharide and chicken interleukin-6
Venue: Journal of Comparative Physiology B

In 4–5-month-old chicken, intravenous injections of bacterial lipopolysaccharide (LPS) induced a dose-dependent fever response and a pronounced increase of circulating interleukin-6 (IL-6). To assess a possible role for IL-6 in the brain of birds, a hypothalamic neuro-glial primary culture from 1-day-old chicken was established. Each well of cultured hypothalamic cells contained some 615 neurons, 1350 astrocytes, and 580 microglial cells on average. Incubation of chicken hypothalamic primary cultures with 10 or 100 µg/ml LPS induced a dose-dependent release of bioactive IL-6 into the supernatant. Populations of hypothalamic neurons (4%) and astrocytes (12%) directly responded to superfusion with buffer containing 10 µg/ml LPS with a transient increase of intracellular calcium, a sign of direct cellular activation. Stimulation of hypothalamic cultures with buffer containing 50 ng/ml chicken IL-6 induced calcium signaling in 11% of neurons and 22% of astrocytes investigated. These results demonstrate that IL-6 is produced in the periphery and in the hypothalamus in response to LPS in chicken. The observed cellular responses of hypothalamic cells to chicken IL-6 indicate that this cytokine may readily be involved in the manifestation of fever in the avian hypothalamus.
Adjustment of fuel loads in stingless bees (Melipona subnitida)
Venue: Journal of Comparative Physiology A

Eusocial bee foragers leave their nest with nectar as flight fuel, therewith reducing the risk of starvation during a foraging trip. Yet, the extra mass results in an increase of energetic expenditure for flight. Thus, bees should tune their fuel loads to the respective foraging situation. In the present study, we investigated the fuel adjustment in the Brazilian stingless bee Melipona subnitida (Apidae, Meliponini). Specifically, we examined whether foragers of this species increase their fuel loads when they have low expectation for nectar collection during a foraging trip. Crop load measurements revealed that nectar foragers carried significantly less fuel on departing the nest than foragers collecting either pollen, clay, or resin. Surprisingly, 75% of nectar foragers left the nest without any detectable amount of nectar, which suggests that the majority of bees collected at nearby nectar sources and avoided an increase in foraging costs. Moreover, foragers increased their fuel loading when repeatedly experiencing empty food sources that had previously been rewarding. These results support our hypothesis and demonstrate that the capability of fuel adjustment is not restricted to honey bees.
Visual cells and visual pigments of the river lamprey revisited
Venue: Journal of Comparative Physiology A

Retinas of the river lamprey Lampetra fluviatilis were studied by microspectrophotometry, electroretinography and single-photoreceptor electrophysiology to reconcile the apparently contradictory conclusions on the nature of lamprey photoreceptor cells drawn in the early work by Govardovskii and Lychakov ( 1984) and in recent studies. In agreement with recent works, we confirmed former identification of short photoreceptors as rods and of long photoreceptors as cones. In line with the results of 1984, we show that within a certain range of light intensities the lamprey retina exhibits “color discrimination”. We found that the overlap of working intensity ranges of rods and cones is not a unique feature of lamprey short receptors, and suggest that rod-cone (possibly color) vision may be common among vertebrates. We show that the decay of meta-intermediates in lamprey cones occurs almost 100 times faster than in typical rod metarhodopsins. Rate of decay of metarhodopsins of lamprey rods take an intermediate position between typical rods and cones. This makes lamprey rhodopsin similar to transmuted cone visual pigment in “rods” of nocturnal geckos. We argue that defining various types of photoreceptors as simply “rods” and “cones” may be functionally correct, but neglects their genetic, biochemical and morphological features and evolutionary history.
Long-term exposure to near-future ocean acidification does not affect the expression of neurogenesis- and synaptic transmission-related genes in the olfactory bulb of European sea bass (Dicentrarchus labrax)
Venue: Journal of Comparative Physiology B

The decrease in ocean pH that results from the increased concentration of dissolved carbon dioxide (CO2) is likely to influence many physiological functions in organisms. It has been shown in different fish species that ocean acidification (OA) mainly affects sensory systems, including olfaction. Impairment of olfactory function may be due to a dysfunction of the GABAergic system and to an alteration of neuronal plasticity in the whole brain and particularly in olfactory bulbs. Recent studies revealed that OA-driven effects on sensory systems are partly mediated by the regulation of the expression of genes involved in neurotransmission and neuronal development. However, these studies were performed in fish exposed to acidified waters for short periods, of only a few days. In the present paper, we investigated whether such effects could be observed in adult (4-years old) European sea bass (Dicentrarchus labrax) exposed to two hypercapnic and acidified conditions (PCO2 ≈ 980 µatm; pH total = 7.7 and PCO2 ≈ 1520 µatm; pH total = 7.5) from the larval stage. In a first approach, we analyzed by qPCR the expression of five genes involved in neurogenesis (DCX) or expressed in GABAergic (Gabra3), glutamatergic (Gria1) or dopaminergic (TH and DDC) neurons in the olfactory bulbs. The tested experimental conditions did not change the expression of any of the five genes. This result would indicate that a potential disruption of the olfactory function of sea bass exposed for a long term to near-future OA, either occurs at a level other than the transcriptional one or involves other actors of the sensory function.