Rate Of Locomotion Research Articles

The record of Vannella species (Vannellidae, Discosea, Amoebozoa) from freshwater sources in Dakahlyia Governorate, Egypt

The River Nile is the main source of fresh water in Egypt, where its water is used for irrigation, drinking, fisheries, industrial uses, and recreation. For sustainable utilization of the River Nile and its branches in the Nile Delta region, it is necessary to monitor regular investigation for the biodiversity of protozoan fauna in the Damietta branch and other freshwater canals in Dakahlyia Governorate. Water samples were collected monthly from different water sources, for 1 year, and examined for protozoans, using phase-contrast microscopy and recorded video films, The genus Vannella Bovee 1965 is recorded for the first time in four freshwater localities: Demietta branch of the River Nile, Mansouria Canal, Bouhia Canal, and Bahr El-Saghir Canal. A detailed morphological description with a brief report of their locomotion has been given for four morphologically different Vannella species. The locomotive form of Vannella sp.1 has a long pointed posterior tail and 2 lateral posterior processes. Such a tail was absent in other Vannella species. Vannella sp.2 is unique among other recorded species, where its locomotive form possesses a long posterior rounded tail region and a frontal hyaloplasm provided with a wavy surface that forms several lobes and finger-like processes during locomotion. In addition, the hyaloplasm produces several transverse waves that vary in thickness and density. The floating form of Vannella sp.2 is of a radial type and has comparatively long hyaline pointed and spiral pseudopodia. The process of transformation of locomotive form to floating form in Vannella sp.2 has been followed up using several recorded video films. The locomotive form of Vannella sp.3 is bear-shaped, while that of Vannella sp.4 has variable shapes from semicircular to rectangular and sometimes fan-shaped. During movement in vivo, locomotive cells of all Vannella species, except Vannella sp.1, move in nearly a straight line, but there were variations in their rate of locomotion. Vannella sp.4 recorded the highest rate (6.8 µm/s), followed by Vannella sp.2 (4.5 µm/s), Vannella sp.3 (2.4 µm/s), and finally Vannella sp.1 (1.0 µm/s). Molecular studies and transmission electron microscope examinations are still needed to confirm the precise identity of each Vannella species.

Evaluation of Type III Adhesive Mortar (ACIII) and Gypsum as Precipitating Agents of Copper and Lead

Heavy metals exhibit characteristics such as nonbiodegradable nature, toxic character, bioaccumulation capability, and ability to transit over long distances. The widespread application of these metal ions in various industrial sectors has led to an increase in their release into the environment. Chemical precipitation has been one of the technologies used to remove heavy metals from wastewater, involving a process in which chemical agents are added to wastewater with dissolved toxic metal ions, which react with the metals, forming insoluble precipitates. Therefore, the present study aimed to assess the potential of gypsum and adhesive mortar type III (ACIII) as precipitating agents for lead (Pb) and copper (Cu) ions, as well as to evaluate the toxicity of precipitation products on Drosophila melanogaster. Experiments using ACIII mortar waste as a precipitating agent for Cu ions were obtained using a glass filter composed of 04 chambers and 04 antechambers, while the potential of gypsum as a Pb ion precipitant was evaluated by adding gypsum powder to a beaker containing a Pb ions solution. The toxicity of the precipitation products was evaluated by observing the mortality and negative geotaxis parameters on D. melanogaster. In the tests using ACIII mortar as a precipitating agent for Cu, retention percentages progressively varied, obtaining 98.82% at a concentration of 30 mg/L. Meanwhile, gypsum obtained retention percentages that varied from 32.83 to 98.61% for Pb. It was found that the precipitates of Cu and Pb resulted in alterations in the survival and locomotion rates of D. melanogaster only at the highest evaluated concentrations. In conclusion, the results obtained indicated that geomaterials such as ACIII mortar and gypsum have potential for the removal of Cu and Pb from aqueous solutions. Moreover, the precipitation stages by these materials also impact in decreasing the toxicity of metal ions to the evaluated model organism.

Evidence for involvement of the alcohol consumption WDPCP gene in lipid metabolism, and liver cirrhosis

Biological pathways between alcohol consumption and alcohol liver disease (ALD) are not fully understood. We selected genes with known effect on (1) alcohol consumption, (2) liver function, and (3) gene expression. Expression of the orthologs of these genes in Caenorhabditis elegans and Drosophila melanogaster was suppressed using mutations and/or RNA interference (RNAi). In humans, association analysis, pathway analysis, and Mendelian randomization analysis were performed to identify metabolic changes due to alcohol consumption. In C. elegans, we found a reduction in locomotion rate after exposure to ethanol for RNAi knockdown of ACTR1B and MAPT. In Drosophila, we observed (1) a change in sedative effect of ethanol for RNAi knockdown of WDPCP, TENM2, GPN1, ARPC1B, and SCN8A, (2) a reduction in ethanol consumption for RNAi knockdown of TENM2, (3) a reduction in triradylglycerols (TAG) levels for RNAi knockdown of WDPCP, TENM2, and GPN1. In human, we observed (1) a link between alcohol consumption and several metabolites including TAG, (2) an enrichment of the candidate (alcohol-associated) metabolites within the linoleic acid (LNA) and alpha-linolenic acid (ALA) metabolism pathways, (3) a causal link between gene expression of WDPCP to liver fibrosis and liver cirrhosis. Our results imply that WDPCP might be involved in ALD.

Light phase does not affect operant sucrose self-administration in adult male C57BL/6JAbr mice

Circadian rhythm can have significant impacts on several physiological domains relevant to the expression of behaviour in mice, including body temperature, corticosterone levels, hormones and immune function. Mice are nocturnal; yet many behavioural studies are performed during the light phase, when mice are naturally inactive. Not surprisingly, the time of day when mice are behaviourally tested can significantly impact on domains such as locomotor activity, e.g. dark phase testing results in higher locomotion rates than light phase testing. However, effects on other behavioural domains, such as cognition, are not well-established, with inconsistent reports on improved cognition during dark phase testing compared to light phase testing in mice. Importantly, the impact of circadian rhythm on operant responding, a common task relevant to research into drug abuse and cognitive disorders, has rarely been investigated in mice. Here we evaluated if testing adult male C57BL/6JAbr mice in operant chambers during the light or dark phase affects acquisition of lever responding, lever discrimination under different fixed ratio (FR) schedules (FR1, FR2, FR4), and/or motivation under a progressive ratio schedule for 10% oral sucrose. We found no effect of circadian rhythm on levels of active and inactive lever pressing, or lever discrimination for oral sucrose at any stage of the experiment. These results may be due to high levels of motivation for sucrose under food restriction and low levels of task complexity limiting detection of any effect of light phase on operant behaviour.

Microplastics Affect Rates of Locomotion and Reproduction via Dietary Uptake in Globally Invasive Snail Physa acuta

Given the omnipresence and potential of entering the food web, the recently emerged pollutant microplastics (MPs) has become a global threat. The impacts of MPs in marine ecosystems are well documented, but the freshwater environment is relatively understudied. Improper disposal of industrial and commercial waste introduces MPs in the freshwater environment where it is either transported to the ocean or eventually settles down to the bottom. To elicit the impacts on components of fitness, the effect of inert particles on the reproductive and behavioral performance on organisms can only be translated after long-term experiments, but most of the available information on freshwater benthos relies only on short-term experiments. This study investigated the rates of microplastic ingestion, locomotion and reproduction in the globally invasive snail Physa acuta (Gastropoda, Pulmonata) at six environmental concentrations (0, 2.5, 5, 10, 20 and 40 mg/200 mL) of polystyrene (PS) MPs particle (size = 32–63µm) for 93 days after maturity. The PS particle ingestion was confirmed by analysis of P. acuta excreta and tissue digestion. P. acuta displayed Type II functional response to MPs. We measured locomotion speed and reproductive rate for 93 days after maturation at 20, 30 and 40 mg/200 mL concentrations of PS MPs equivalent to 500 × 104, 750 × 104 and 1000 × 104 particles/200 mL, respectively. Average locomotion speed and egg capsule production were significantly lower in the MP applied environment than in the control. The percent reduction in ovisac production and egg hatching success were a direct function of MP concentrations in the medium., although, in a natural setup, plastic debris was observed as a frequent oviposition substrate for P. acuta favoring the species in dispersal. The present results point to a higher tolerance of P. acuta to MPs and their role as a vehicle of MP transfer from sediment to fish.

C. elegans dkf-1 (Protein Kinase D1) mutants have age-dependent defects in locomotion and neuromuscular transmission.

Changes in neuronal function that occur with age are an area of increasing importance. A potential significant contributor to age-dependent decline may be alterations to neurotransmitter release. Protein kinases, such as Protein Kinase C and Protein Kinase A, are well characterised modulators of neuronal function and neurotransmission. Protein Kinase D (PRKD) is a serine/threonine kinase whose role in neurons is less well characterised. Here we report that mutations in the C. elegans PRKD homolog, dkf-1 , show an acceleration in age-dependent decline of locomotion rate and an alteration to age-dependent changes in aldicarb sensitivity. These effects could be explained by a pre- or post-synaptic function of the protein kinase as the animal ages.

Factor quinolinone inhibitors alter cell morphology and motility by destabilizing interphase microtubules

Factor quinolinone inhibitors are promising anti-cancer compounds, initially characterized as specific inhibitors of the oncogenic transcription factor LSF (TFCP2). These compounds exert anti-proliferative activity at least in part by disrupting mitotic spindles. Herein, we report additional interphase consequences of the initial lead compound, FQI1, in two telomerase immortalized cell lines. Within minutes of FQI1 addition, the microtubule network is disrupted, resulting in a substantial, although not complete, depletion of microtubules as evidenced both by microtubule sedimentation assays and microscopy. Surprisingly, this microtubule breakdown is quickly followed by an increase in tubulin acetylation in the remaining microtubules. The sudden breakdown and partial depolymerization of the microtubule network precedes FQI1-induced morphological changes. These involve rapid reduction of cell spreading of interphase fetal hepatocytes and increase in circularity of retinal pigment epithelial cells. Microtubule depolymerization gives rise to FH-B cell compaction, as pretreatment with taxol prevents this morphological change. Finally, FQI1 decreases the rate and range of locomotion of interphase cells, supporting an impact of FQI1-induced microtubule breakdown on cell motility. Taken together, our results show that FQI1 interferes with microtubule-associated functions in interphase, specifically cell morphology and motility.

Diterpene glycosides from Holothuria scabra exert the α-synuclein degradation and neuroprotection against α-synuclein-Mediated neurodegeneration in C. elegans model

Ethnopharmacological relevanceHolothuria (Metriatyla) scabra Jaeger (H. scabra), sea cucumber, is the marine organism that has been used as traditional food and medicine to gain the health benefits since ancient time. Although our recent studies have shown that crude extracts from H. scabra exhibited neuroprotective effects against Parkinson's disease (PD), the underlying mechanisms and bioactive compounds are still unknown. Aim of the studyIn the present study, we examined the efficacy of purified compounds from H. scabra and their underlying mechanism on α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration in a transgenic Caenorhabditis elegans PD model. Material and methodsThe H. scabra compounds (HSEA-P1 and P2) were purified and examined for their toxicity and optimal dose-range by food-clearance and lifespan assays. The α-synuclein degradation and neuroprotection against α-synuclein-mediated neurodegeneration were determined using transgenic C. elegans model, Punc-54::α-syn and Pdat-1:: α-syn; Pdat-1::GFP, respectively, and then further investigated by determining the behavioral assays including locomotion rate, basal slowing rate, ethanol avoidance, and area-restricted searching.The underlying mechanisms related to autophagy were clarified by quantitative PCR and RNAi experiments. ResultsOur results showed that HSEA-P1 and HSEA-P2 significantly diminished α-synuclein accumulation, improved motility deficits, and recovered the shortened lifespan. Moreover, HSEA-P1 and HSEA-P2 significantly protected dopaminergic neurons from α-synuclein toxicity and alleviated dopamine-associated behavioral deficits, i.e., basal slowing, ethanol avoidance, and area-restricted searching. HSEA-P1 and HSEA-P2 also up-regulated autophagy-related genes, including beclin-1/bec-1, lc-3/lgg-1, and atg-7/atg-7. RNA interference (RNAi) of these genes in transgenic α-synuclein worms confirmed that lc-3/lgg-1 and atg-7/atg-7 were required for α-synuclein degradation and DAergic neuroprotection activities of HSEA-P1 and HSEA-P2. NMR and mass spectrometry analysis revealed that the HSEA-P1 and HSEA-P2 contained diterpene glycosides. ConclusionThese findings indicate that diterpene glycosides extracted from H. scabra decreases α-synuclein accumulation and protects α-synuclein-mediated DAergic neuronal loss and its toxicities via lgg-1 and atg-7.

Quantitative study of the behavior of two broadcast spawners, the sea urchins Strongylocentrotus intermedius and Mesocentrotus nudus, during mass spawning events in situ.

BackgroundThe spatial distribution of spawners and temporal parameters of spawning in motile invertebrates with external fertilization might influence reproductive success. However, to date, data on the prespawning and spawning behaviors of broadcast spawners in the field have been scarce and mostly qualitative. The present study was intended to clarify the behavioral adaptations of two sea urchin species, Strongylocentrotus intermedius and Mesocentrotus nudus, using quantitative analysis of their behavior during mass spawning events under natural conditions.MethodsWe analyzed in situ video recordings of sea urchin behavior obtained during six spawning seasons (2014–2019). The total number of specimens of each sea urchin species and the numbers of spawning males and females were counted. Quantitative parameters of sea urchin spawning (numbers of gamete batches, release duration of one gamete batch, time intervals between gamete batches and total duration of spawning) and movement (step length of spawners and nonspawners before and during spawning and changes in distances between males/nonspawners and females) were determined.ResultsFor each species, 12 mass spawning events were recorded in which 10 or more individuals participated. The temporal dynamics of the numbers of males and females participating in mass spawning were well synchronized in both species; however, males began to spawn earlier and ended their spawning later than females. In both species, the most significant intersex difference was the longer spawning duration in males due to the longer pause between gamete batches. The total duration of gamete release did not differ significantly between sexes. The average duration of sperm release during mass spawning events was longer than solitary male spawning. Males and females showed significant increases in the locomotion rate 35 min before the start of spawning and continued to actively move during spawning. An increase in movement rate before spawning in males and females was induced by environmental factor(s). Nonspawners of both species showed increased locomotion activity but in the presence of spawning neighbors and less prominently than spawners. On a vertical surface, both echinoids moved strictly upward. On flat surfaces, males, females and nonspawners of both echinoids became closer during spawning.DiscussionWe showed that two sea urchin species with planktotrophic larvae display similar behavioral adaptations aimed at enhancing reproductive success. The high sensitivity of sea urchins, primarily males, to some environmental factors, most likely phytoplankton, may be considered a large-scale adaptation promoting the development of mass spawning events. The longer spawning duration in males and increased movement activity before and during spawning in both sexes may be considered small-scale adaptations promoting approach of males and females and enhancing the chances of egg fertilization.

The effect of mobbing vocalizations on risk perception in common mynas (Acridotheres tristis)

Animals emit predator-elicited calls in response to potential predation threats. These vocalizations induce a variety of anti-predator behaviors in conspecific receivers ranging from moving away from predators (alarm calls) to rallying conspecifics to fend them off (mobbing calls). While much is known about the immediate response to alarm calls, less is known about how mobbing calls influence subsequent antipredator decisions. Mobbing calls stimulate harassment of a potential predator. Therefore we predicted that hearing a mobbing call would make animals less likely to immediately flee an approaching threat. To study the potential effect of mobbing vocalizations on risk assessment, we primed common mynas (Acridotheres tristis) with a series of different stimuli and studied the variation in their subsequent decisions to flee an approaching human by quantifying flight initiation distance (FID). We found that although mynas increased their rate of locomotion after hearing mobbing calls, their subsequent decision to flee was not influenced. We also found that an individual’s propensity to move and look explained some variation in FID. This suggests that while mobbing calls do not influence subsequent decisions to flee, they do affect subsequent behavior.

Cercarial swimming performance and its potential role as a key variable of trematode transmission.

Trematode transmission in aquatic habitats from molluscan intermediate host to vertebrate or invertebrate target host is typically undertaken by a free-living stage known as cercariae. Active locomotion by cercariae is a key aspect of the transmission process with the swimming speed potentially contributing to infection success. Individual cercarial species swim at different speeds but the significance of this to infection potential has not been determined. This study, using data from the scientific literature, investigates the role of swimming speed in relation to cercarial morphology, host-searching strategies and target host species. Larger cercariae swim faster than smaller ones with tail length being the principal factor controlling locomotion rates. Different cercarial morphotypes swim at different speeds, in particular, furcocercariae, with the exception of the schistosomes, being faster swimmers than mono-tailed cercariae. Host-searching behaviour has a significant influence on swimming speeds with 'active-searching' strategies swimming slower than those adopting 'active-waiting' or 'prey mimcry' strategies. Vertebrate-infecting cercariae swim faster than those infecting invertebrates with species targeting fish demonstrating the highest locomotion rates and those targeting arthropods the slowest speeds. The adaptions of individual cercarial swimming speeds to biological variables and their interactions with the physical processes of aquatic habitats are discussed.

Lightweight and Wearable X‐Ray Shielding Material with Biological Structure for Low Secondary Radiation and Metabolic Saving Performance

AbstractPreventing X‐rays from reaching the human body is of great significance for the safe implementation of a wide range of related technologies. However, the current materials are commonly accompanied with low mechanical properties and backscatter radiation hazards. In this study, a structural material with high mass attenuation coefficients in a wide energy range (10–100 keV) is developed. The integration of high‐Z elements in hierarchical collagen nanofibers strongly reduces the backscatter radiation, resulting in only 28% of secondary radiation compared with a standard lead plate. The water vapor permeability of the engineered leather is nearly 340 times higher than commonly used synthetic and natural polymers. Compared with the commercial rubber‐based materials, the tensile strength of the engineered leather increased to 27.22 MPa (tenfold increase) and tear strength to 78.5 N mm−1 (threefold increase), respectively. A fully tailored engineered leather suit provides a 24.7% lower metabolic rate of locomotion and 67% reduced body heat compared with commercial lead aprons, which can facilitate better performance and safety during intensive activities in the health care and nuclear industries. This work lays a foundation for the engineering of next‐generation X‐ray shielding materials with potential large impact on the X‐ray application landscape.

Evaluation of the potential toxicity of haloperidol, clozapine and a new putative antipsychotic molecule, PT-31, in an alternative toxicity model, C. elegans

Schizophrenia is a disabling mental illness that affects approximately 1% of the world population. The treatment of this disorder is based on two generations of substances, typical antipsychotics, such as haloperidol, and atypical antipsychotics, such as clozapine, which can cause severe adverse effects. Therefore, the development of novel molecules that are safe and efficacious to treat the disease is crucial. PT-31 is a putative α2-adrenoceptor agonist effective against schizophrenia positive and cognitive symptoms in mice. C. elegans is an alternative model that has been successfully used to investigate the toxicity of a variety of substances. The present study aimed to evaluate the potential toxicity of the new molecule PT-31 and the antipsychotics haloperidol and clozapine in C. elegans. The evaluation was carried out based on toxicity endpoint tests, survival, developmental and behavioral assays. The antipsychotics haloperidol and clozapine decreased nematode survival by 30 and 40%, respectively, exposing the potential toxicity of these substances whereas PT-31 was safer based on this parameter. Similar results were obtained in the nematode developmental assay: haloperidol and clozapine significantly reduced nematode body length and area, whereas PT-31 preserved the normal development of the nematodes. The behavioral assessment was based on the frequency of body bends; none of the antipsychotics affected the locomotion rate of the nematodes, and PT-31 also did not compromise this parameter, demonstrating the safety of this new compound and reinforcing the recognized toxicity of antipsychotics.

Critical Role of p38 in Spinal Cord Injury by Regulating Inflammation and Apoptosis in a Rat Model

To evaluate the effect of p38 pathway on spinal cord injury (SCI), a rat model of SCI was performed. We determined the effect of p38 on SCI and SCI related inflammation, apoptosis, and autophagy. SCI is a severe clinical problem worldwide. It is difficult to prevent cell necroptosis and promote the survival of residual neurons after SCI. p38, a class of mitogen-activated protein kinases, its effect on SCI and SCI related inflammation, apoptosis, and autophagy have not been studied very well. The rats were randomly divided into the following four groups: the sham-operated (sham) group, the SCI group, the SCI + vehicle group, and the SCI + SB203580 (10 mg/kg) group. The p38 inhibitor SB203580 was administered by oral (10 mg/kg/d) gavage once per day for 14 days. Neurological recovery was assessed using the Basso, Beattie, and Bresnahan locomotion rating scale. Apoptosis, autophagy, and inflammation related proteins were measured by enzyme-linked immunosorbent assay kits or western blotting. Our results showed that p38 was upregulated after SCI from day 3, which was paralleled with the levels of its proteins ATF-2, suggesting an increase in p38 activity. Our results showed administration of SB203580 attenuated histopathology and promoted locomotion recovery in rats after SCI. SB203580 administration significantly inhibited inflammatory cytokines levels as well as the inflammation signaling pathway. SB203580 administration also modulated the apoptosis and autophagy signaling pathway. Our findings suggest that p38 inhibitor SB203580 treatment alleviates secondary SCI by inhibiting inflammation and apoptosis, thereby promoting neurological and locomoter functional recovery, thus suggest the important role of p38 in neuronal protection after SCI. N/A.

Comparison of two modified methods of intrathecal catheterization in rats.

The study designed to compare two different methods of intrathecal catheterization in rats and to develop a simple and safe drug administration in cervical spinal canal of rats. The subarachnoid catheterization was performed via either atlanto-occipital membrane or laminectomy at L3–4 in rats. Body weight, Basso, Beattie, and Bresnahan (BBB) locomotion rating scores and forelimb locomotor rating scale (FLS) were measured on pre-operative day 1 and postoperative day 1, 7, 14, respectively. FLS score of 37.5% rats and BBB score of 50% rats in the atlanto-occipital approach (AOA) group decreased, but no rats showed locomotor impairment in the lumber approach (LA) group. The mean body weight of rats in AOA group reduced significantly compared with LA group. In LA group, 62.5% of catheter tips were located at T1, and in AOA group, the tips of catheter located at C2 in 62.5% cases. The PE10 catheter can be successfully inserted into the spinal intrathecal space for chronic delivery of drugs either via L3–L4 interlaminar space or via atlanto-occipital membrane. And the subarachnoid catheterization via L3–L4 interlaminar space could be easily placed at T1 with little complication.

Effects of maximum residue limit of triflumezopyrim exposure on fitness of the red imported fire ant Solenopsis invicta.

The impact of exposure to free feeding concentrations of triflumezopyrim to the red imported fire ant, Solenopsis invicta, in maximum residue tolerances for 56 days was investigated to understand whether triflumezopyrim, a novel neonicotinoid, poses unacceptable risks to the environment. Our results demonstrated that neither 0.5 μg/ml nor 0.2 μg/ml triflumezopyrim have a significant impact on the growth of the S. invicta colony and their food consumption (sugar water and locusts) during the length of treatment. While both 0.5 μg/ml and 0.2 μg/ml triflumezopyrim improved the grasping ability of S. invicta, and 0.5 μg/ml not 0.2 μg/ml triflumezopyrim increased their rate of locomotion. In addition, although 0.5 μg/ml and 0.2 μg/ml triflumezopyrim increased their individual aggressiveness index, the probability of the survival of S. invicta was not impacted by triflumezopyrim treatments in aggressive group encounters. This study suggests that triflumezopyrim did not have a negative impact on the fitness of S. invicta at 0.5 μg/ml and 0.2 μg/ml exposures.

Shift down, look up: A test of the non‐linearity and fear hypothesis in a non‐vocal skink

AbstractThe non‐linearity and fear hypothesis predicts that certain non‐linear sounds are one way to evoke antipredator responses in both birds and mammals. This hypothesis, however, has not been studied in non‐vocal species or in reptiles. Such a study would be important because if non‐linear sounds are evocative even in a species that does not produce sounds, then there may be generally salient cues of risk in these sounds. We asked whether non‐vocal lizards, white‐bellied copper‐striped skinks (Emoia cyanura), respond to experimentally broadcast non‐linearities. This species is ideal to ask the question in because prior research has shown that they respond to predator sounds and alarm calls of other species even though they are not vocal. We conducted playback experiments with three computer‐generated simulated non‐linearities to assess whether or not skinks increased antipredator behavior after hearing them. We controlled for novelty by broadcasting a 3‐kHz, 500‐ms pure tone and tropical kingbird (Tyrannus melancholicus) song. Our treatments consisted of a 3‐kHz, 400‐ms pure tone followed by a frequency shift up to 5‐kHz for 100‐ms, a 3‐kHz, 400‐ms pure tone to frequency shift down to 1‐kHz for 100‐ms, and a pure tone followed by 100‐ms of white noise. Following a total of 222 playbacks, we categorized responses into looking, locomotion, and high locomotion, focusing on how skinks changed their rates of time allocation from baseline. We examined 95% confidence intervals to identify whether skinks responded to playbacks and fitted general linear models followed by pairwise comparisons to ask whether skinks discriminated between broadcast stimuli. We found that skinks were especially responsive to frequency downshifts: They significantly increased looking and locomotion, consistent with our predictions based on the non‐linearity and fear hypothesis. Surprisingly, they decreased rates of looking behavior after hearing frequency upshifts, possibly suggesting an increase in relaxed behavior. While skinks responded to noise by increasing their rate of locomotion, this response was not significantly different from controls. We conclude that skinks increase antipredator behavior after hearing downshifts more than any other type of non‐linearity. This provides some support for the non‐linearity and fear hypothesis; even non‐vocal species may respond fearfully to specific types of non‐linear sounds.

Ocean warming combined with lower omega-3 nutritional availability impairs the cardio-respiratory function of a marine fish.

Highly unsaturated fatty acids of the omega-3 series (HUFA) are major constituents of cell membranes, yet are poorly synthesised de novo by consumers. Their production, mainly supported by aquatic microalgae, has been decreasing with global change. The consequences of such reductions may be profound for ectotherm consumers, as temperature tightly regulates the HUFA content in cell membranes, maintaining their functionality. Integrating individual, tissue and molecular approaches, we examined the consequences of the combined effects of temperature and HUFA depletion on the key cardio-respiratory functions of the golden grey mullet, an ectotherm grazer of high ecological importance. For 4months, fish were exposed to two contrasting HUFA diets [4.8% eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA) on dry matter (DM) versus 0.2% EPA+DHA on DM] at 12 and 20°C. Ventricular force development coupled with gene expression profiles measured on cardiac muscle suggest that combining HUFA depletion with warmer temperatures leads to: (1) a proliferation of sarcolemmal and sarcoplasmic reticulum Ca2+ channels and (2) a higher force-generating ability by increasing extracellular Ca2+ influx via sarcolemmal channels when the heart has to sustain excessive effort due to stress and/or exercise. At the individual scale, these responses were associated with a greater aerobic scope, maximum metabolic rate and net cost of locomotion, suggesting the higher energy cost of this strategy. This impaired cardiac performance could have wider consequences for other physiological performance such as growth, reproduction or migration, all of which greatly depend on heart function.

Restoring electrical connection using a conductive biomaterial provides a new therapeutic strategy for rats with spinal cord injury

Spinal cord injury (SCI) involves damage to the central nervous system, and there is no effective treatment available currently. The injured spinal cord is unable to transmit physiological electrical signals caudal to the location of the injury after a complete transection. In this study, we attempted to use a conductive biomaterial as a novel scaffold to aid SCI repair. A composite biomaterial was fabricated by embedding conductive polypyrrole (PPy) in an electrospun polylactic acid (PLA) nanofibrous scaffold (PLA/PPy scaffold), and an electrospun PLA nanofibrous scaffold without the PPy component was used as a control. The scaffolds were implanted into rats having complete T9 spinal cord resection. Immunofluorescent staining, western blot analysis, and TUNEL assay were used to study histological changes in injured spinal cord tissues. Our data demonstrated that PLA/PPy scaffolds had beneficial effects, as evident from the motor evoked-potentials (MEPs) test and Basso, Beattie, and Bresnahan (BBB) locomotion rating scale. Implantation of the PLA/PPy scaffold significantly alleviated secondary tissue damage by reducing apoptosis and autophagy in neural cells in comparison with the implantation of the control PLA scaffold. Notably, six weeks after injury, the use of PLA/PPy scaffolds significantly reduced the activation of astrocytes and increased axonal regeneration, as indicated by immunofluorescent markers (GFAP and NF200) in the region of injury. Our present study suggests that restoring electrical conductivity using a biological scaffold is beneficial to the microenvironment and favorable for the regeneration and functional recovery of spinal cord tissue in an SCI rat model.

Limuloid trackways from Permian-Triassic continental successions of North China

Forty-four well-preserved specimens of Kouphichnium, a typical limuloid (horseshoe crab) trackway, are reported and systematically studied for the first time from continental Upper Permian to Lower Triassic successions in North China. A new ichnotaxonomic system of Kouphichnium is proposed according to the ichnotaxobase of limuloid trackways, including simple foot imprints (T), pusher imprints (P), median impressions (M) and genal spine impressions (GS). In total, one ichnogenus and six ichnospecies are recognized, one of which is new: Kouphichnium liulinensis sp. nov. Ichnogenus Paramphibius is regarded as a synonym of Kouphichnium and the diagnoses of ichnogenus Kouphichnium and its two early ichnospecies, i.e. type ichnospecies Kouphichnium lithographicum Oppel, and Kouphichnium didactylum Willard, are revised. A morphological-palaeoethological pattern is proposed in reference to these ichnospecies from the continental Upper Permian to Lower Triassic successions in North China. These six ichnospecies are assigned to six types in the new ichnotaxonomic system and the locomotion rates of each type can be ranked by the possible speed index λ. The size of trackmaker is estimated from the external width of the trackway, and it shows a drastic decrease from the Late Permian to Early Triassic, followed by a gradual increase in the Early Triassic. This size variation of trackmakers (limuloids) during the Permian-Triassic transition, especially the drastic drop, probably reflects the intensive environmental stress during the biotic crisis. In addition, the analysis of the sizes of pusher imprints (P) from certain well-preserved trackways suggests a potential sexual dimorphism of limuloids.