Ganglionated Plexus Ablation Procedures to Treat Vasovagal Syncope.

Vasovagal syncope (VVS) refers to a heterogeneous group of conditions whereby the cardiovascular reflexes normally controlling the circulation are interrupted irregularly in response to a trigger, resulting in vasodilation, bradycardia, or both. VVS affects one-third of the population at least once in their lifetime or by the age of 60, reduces the quality of life, and may cause disability affecting certain routines. It poses a considerable economic burden on society, and, despite its prevalence, there is currently no proven pharmacological treatment for preventing VVS. The novel procedure of ganglionated plexus (GP) ablation has emerged rapidly in the past two decades, and has been proven successful in treating syncope. Several parameters influence the success rate of GP ablation, including specific ablation sites, localization and surgical techniques, method of access, and the integration of other interventions. This review aims to provide an overview of the existing literature on the physiological aspects and clinical effectiveness of GP ablation in the treatment of VVS. Specifically, we explore the association between GPs and VVS and examine the impact of GP ablation procedures as reported in human clinical trials. Our objective is to shed light on the therapeutic significance of GP ablation in eliminating VVS and restoring normal sinus rhythm, particularly among young adults affected by this condition.

Personality traits differentially affect components of reproductive success in a Neotropical poison frog.

Individual reproductive success has several components, including the acquisition of mating partners, offspring production, and offspring survival until adulthood. While the effects of certain personality traits-such as boldness or aggressiveness-on single components of reproductive success are well studied, we know little about the composite and multifaceted effects behavioural traits can have on all the aspects of reproductive success. Behavioural traits positively linked to one component of reproductive success might not be beneficial for other components, and these effects may differ between sexes. We investigated the influence of boldness, aggressiveness, and exploration on the number of mating partners, mating events, and offspring surviving until adulthood in males and females of the Neotropical poison frog Allobates femoralis. Behavioural traits had different-even opposite-effects on distinct components of reproductive success in both males and females. For example, males who displayed high levels of aggressiveness and exploration (or low levels of aggressiveness and exploration) managed to attract high number of mating partners, while males with low levels of boldness, low levels of aggressiveness, and high levels of exploration had the most offspring surviving until adulthood. Our results therefore suggest correlational selection favouring particular combinations of behavioural traits.

Experimental investigation of the responses of meadow buttercup (Ranunculus acris L.) to sodic salinity and its implications for habitat monitoring.

Ranunculus acris L. is a native species widely distributed throughout Europe and is invasive in nonnative areas, causing substantial economic losses in pasture productivity. The present study examined the effects of sodic salinity on the growth and functioning of this species. Salinity stresses the germination process and seedling growth, indicating that the studied species experience serious limitations at 60-90 mmol dm-3 NaCl and cannot establish in habitats where salinity is equal to or greater than 150 mmol dm-3 NaCl. R. acris is tuned to subsaline habitats characteristic of temperate meadows, as its growth and functioning were the best when the plants were treated with 30 mmol dm-3 NaCl. Increasing salinity (60 and 90 mmol dm-3 NaCl) hampered growth, leaf morphology and photosynthesis but not mineral nutrition, as Na accumulation seemed to be the most outlined effect of NaCl application. Changes in leaf morphological characteristics coordinated well with Na content in those organs, which indicates that leaf appearance can be easily catchable sign of progressing salinity. Ultimately, progressing salinity reduces the competitiveness of the studied species, shifting its strategy to ruderal behavior, but under subsaline conditions, the strategy of this species seems to be most balanced.

A geometric morphometric analysis of variation in Australian frog ilia and taxonomic interpretations.

Anurans including frogs and toads exhibit an ilium that is often regarded as taxonomically diagnostic. The ilium, one of the three paired bones that make up the pelvic girdle, has been important in the fossil record for identifying anuran morphotypes. Osteological collections for Australian frogs are rare in herpetological museums, and skeletonizing whole-bodied specimens requires destroying soft tissue morphology which is valuable to anuran specialists working on living species. Computed tomography scans provide the opportunity to study anuran osteology without the loss of soft tissues. Our study, based on microcomputed tomography scans of extant Australian frogs from the public repository Morphosource and from museum collections focuses on the morphological differences between Australian frogs at the familial and generic levels using geometric morphometrics to compare the diagnostic shape of the ilium. Principal component analysis (PCA) and canonical variate analysis (CVA) were conducted to assess differences in the ilium between supraspecific groups of Australian frogs. The canonical variates analysis accurately predicted group membership (i.e., the correct family) with up to 76.2% success for cross-validated predictions and 100% of original group predictions. While the sample was limited to familial and generic level analyses, our research shows that ilial morphology in Australian frogs is taxonomically informative. This research provides a guide for identifying Australian anurans, including fossils, as well as new information relevant to considerations about their phylogenetic relationships, and the potential use of the fossil record to enhance efforts to conserve threatened living frog species.

Effects of temperature and precipitation changes on shifts in breeding phenology of an endangered toad.

In the last century, a plethora of species have shown rapid phenological changes in response to climate change. Among animals, amphibians exhibit some of the greatest responses since their activity strongly depends on temperature and rainfall regimes. These shifts in phenology can have negative consequences for amphibian fitness. Thus, understanding phenological changes in amphibians is pivotal to design conservation actions to mitigate climate change effects. We used data on Common Spadefoot Toad (Pelobates fuscus) reproductive migration to wetlands over a period of 8 years in Italy to (i) identify the factors related to breeding migrations, (ii) assess potential phenological shifts in the breeding period, and (iii) determine which climatic factors are related to the observed phenological shifts. Our results showed that toads migrate to spawning sites preferably in early spring, on rainy days with temperatures of 9-14 °C, and with high humidity. Furthermore, despite an increase in average temperature across the study period, we observed a delay in the start of breeding migrations of 12.4 days over 8 years. This counterintuitive pattern was the result of a succession of hot and dry years that occurred in the study area, highlighting that for ephemeral pond breeders, precipitation could have a larger impact than temperature on phenology. Our results belie the strong presumption that climate change will shift amphibian phenology toward an earlier breeding migration and underline the importance of closely investigating the environmental factors related to species phenology.

Widespread learned predator recognition to an alien predator across populations in an amphibian species.

Alien predators are a major cause of decline and extinction of species worldwide, since native organisms are rarely equipped with specific antipredatory strategies to cope with them. However, phenotypic plasticity and learned predator recognition may help prey populations to survive novel predators. Here we examine geographical variation in the learning ability of larval spadefoot toads (Pelobates cultripes) to recognize invasive predatory crayfish (Procambarus clarkii). We compare the learning-mediated behavioural responses of tadpoles from six populations across two regions in Spain (central and southern), with different histories of exposure to the presence of the invasive species. Two of the populations showed innate recognition of chemical cues from the invasive crayfish, whereas three of them learned to recognize such cues as a threat after conditioning with conspecific alarm cues. Learning abilities did not differ among southern populations, but they did among central populations. We assessed patterns of genetic variation within and among these two regions through microsatellite markers and found low genetic divergence among the southern populations but greater differentiation among the central ones. We hypothesize that similar responses to the invasive crayfish in southern populations may have arisen from a combination of extended historical exposure to this introduced predator (~ 50 y) and higher levels of gene flow, as they inhabit a highly interconnected pond network. In contrast, populations from central Spain show lower connectivity, have been exposed to the invasive crayfish for a shorter period of time, and are more divergent in their plastic responses.

The genome sequence of the critically endangered Kroombit tinkerfrog ( Taudactylus pleione).

The Kroombit tinkerfrog ( Taudactylus pleione) is a stream-dwelling amphibian of the Myobatrachidae family. It is listed as Critically Endangered and is at high risk of extinction due to chytridiomycosis. Here, we provide the first genome assembly of the evolutionarily distinct Taudactylus genus. We sequenced PacBio HiFi reads to assemble a high-quality long-read genome and identified the mitochondrial genome. We also generated a global transcriptome from a tadpole to improve gene annotation. The genome was 5.52 Gb in length and consisted of 4,196 contigs with a contig N50 of 8.853 Mb and an L50 of 153. This study provides the first genomic resources for the Kroombit tinkerfrog to assist in future phylogenetic, environmental DNA, conservation breeding, and disease susceptibility studies.

Locomotion rhythm makes power and speed.

This article addresses two questions, why certain animals (frogs, breaststroke swimmers, hovering fliers, jellyfish) push rapidly against the surrounding fluid and then reach forward slowly, and whether this rhythm of propulsion is a manifestation of the universal phenomenon of design evolution in nature. Emphasis is on the distribution of time periods of locomotion in which, during the driving phase of cyclic movement (the motive stroke, phases 1 and 2, in alternating sequence with the dissipative stroke, phase 3), the work is generated (phase 1) and dissipated (phase 2). The relative lengths of the characteristic times t1 and t2 of the phases 1 and 2, are predicted. The relative duration of the proposed three phases of a cycle is the 'rhythm'. The analysis is based on a model of how the effective cross-sections of the stroking body parts impact the surrounding medium, water, or air, and the total power required to account for the kinetic energy losses during phases 2 and 3, which are due to drag forces posed by the surrounding medium. The body configuration (limbs' cross-sections) determines the limbs' velocities that maximize mean power, and the times t1 and t2 within the motive stroke. Emphasis is placed on the freedom to change the evolving design. Freedom is represented in two ways: the number of degrees of freedom in changing the dimensions of the model and its deformation in time, and the effect that evolutionary changes have on the access that the body has to its available space. Freedom to change the locomotion design leads to greater power and speed.

Using eDNA to understand predator-prey interactions influenced by invasive species.

Invasive predatory species may alter population dynamic processes of their prey and impact biological communities and ecosystem processes. Revealing biotic interactions, however, including the relationship between predator and prey, is a difficult task, in particular for species that are hard to monitor. Here, we present a case study that documents the utility of environmental DNA analysis (eDNA) to assess predator-prey interactions between two invasive fishes (Lepomis gibbosus, Pseudorasbora parva) and two potential amphibian prey species, (Triturus cristatus, Pelobates fuscus). We used species-specific TaqMan assays for quantitative assessment of eDNA concentrations from water samples collected from 89 sites across 31 ponds during three consecutive months from a local amphibian hotspot in Germany. We found a negative relationship between eDNA concentrations of the predators (fishes) and prey (amphibians) using Monte-Carlo tests. Our study highlights the potential of eDNA application to reveal predator-prey interactions and confirms the hypothesis that the observed local declines of amphibian species may be at least partly caused by recently introduced invasive fishes. Our findings have important consequences for local conservation management and highlight the usefulness of eDNA approaches to assess ecological interactions and guide targeted conservation action.

Their fates intertwined: diversification patterns of the Asian gliding vertebrates may have been forged by dipterocarp trees.

The repeated evolution of gliding in diverse Asian vertebrate lineages is hypothesized to have been triggered by the dominance of tall dipterocarp trees in the tropical forests of Southeast Asia. These dipterocarp forests have acted as both centres of diversification and climatic refugia for gliding vertebrates, and support most of their extant diversity. We predict similarities in the diversification patterns of dipterocarp trees and gliding vertebrates, and specifically test whether episodic diversification events such as rate shifts and/or mass extinctions were temporally congruent in these groups. We analysed diversification patterns in reconstructed timetrees of Asian dipterocarps, the most speciose gliding vertebrates from different classes (Draco lizards, gliding frogs and Pteromyini squirrels) and compared them with similar-sized clades of non-gliding relatives (Diploderma lizards, Philautus frogs and Callosciurinae squirrels) from Southeast Asia. We found significant declines in net-diversification rates of dipterocarps and the gliding vertebrates during the Pliocene-Pleistocene, but not in the non-gliding groups. We conclude that the homogeneity and temporal coincidence of these rate declines point to a viable ecological correlation between dipterocarps and the gliding vertebrates. Further, we suggest that while the diversification decay in dipterocarps was precipitated by post-Miocene aridification of Asia, the crises in the gliding vertebrates were induced by both events concomitantly.

Critical calls: Circadian and seasonal periodicity in vocal activity in a breeding colony of Panamanian golden frogs (Atelopus zeteki).

The Panamanian golden frog (Atelopus zeteki) is a critically endangered species and currently is believed to survive and reproduce only in human care. Panamanian golden frog males are considerably vocal which may be an important component in their successful reproduction, though little is currently known about their calls. To better understand the behavior and vocal patterns of this species and to improve breeding efforts in the assurance colony, we employed individual sound recording of male advertisement calls and acoustic monitoring of a breeding colony to investigate variation in the vocal behavior of Panamanian golden frogs. The goal was to capture variability within and among frogs as well as patterns of periodicity over time. First, the advertisement calls from individual male Panamanian golden frogs were recorded, and acoustic parameters were analyzed for individual differences. Results suggest that male advertisement calls demonstrate individual- and population specificity. Second, data collected through a year-long acoustic monitoring of the breeding colony were investigated for circadian and circannual periodicity. Male vocal activity revealed a circadian periodicity entrained by the daily light schedule. Seasonal periodicity was also found with highest vocal activities between December and March. The finding of a seasonal periodicity is worth noting given that the population had been bred for 20 years under constant environmental conditions. Finally, results suggest that vocal activity was responsive to daily animal care activity. Vocal activity decreased substantially when personnel entered the room and engaged in animal husbandry activities. The findings illustrate the usefulness of acoustic monitoring to provide insight into animal behavior in a zoo setting in a key breeding colony of endangered animals, and calling pattern observations may be utilized to modify husbandry practices to improve Panamanian golden frog breeding success and general care.

Tissue-specific in vivo transformation of plasmid DNA in Neotropical tadpoles using electroporation.

Electroporation is an increasingly common technique used for exogenous gene expression in live animals, but protocols are largely limited to traditional laboratory organisms. The goal of this protocol is to test in vivo electroporation techniques in a diverse array of tadpole species. We explore electroporation efficiency in tissue-specific cells of five species from across three families of tropical frogs: poison frogs (Dendrobatidae), cryptic forest/poison frogs (Aromobatidae), and glassfrogs (Centrolenidae). These species are well known for their diverse social behaviors and intriguing physiologies that coordinate chemical defenses, aposematism, and/or tissue transparency. Specifically, we examine the effects of electrical pulse and injection parameters on species- and tissue-specific transfection of plasmid DNA in tadpoles. After electroporation of a plasmid encoding green fluorescent protein (GFP), we found strong GFP fluorescence within brain and muscle cells that increased with the amount of DNA injected and electrical pulse number. We discuss species-related challenges, troubleshooting, and outline ideas for improvement. Extending in vivo electroporation to non-model amphibian species could provide new opportunities for exploring topics in genetics, behavior, and organismal biology.

Frog phylogeny: A time-calibrated, species-level tree based on hundreds of loci and 5,242 species.

Large-scale, time-calibrated phylogenies from supermatrix studies have become crucial for evolutionary and ecological studies in many groups of organisms. However, in frogs (anuran amphibians), there is a serious problem with existing supermatrix estimates. Specifically, these trees are based on a limited number of loci (15 or fewer), and the higher-level relationships estimated are discordant with recent phylogenomic estimates based on much larger numbers of loci. Here, we attempted to rectify this problem by generating an expanded supermatrix and combining this with data from phylogenomic studies. To assist in aligning ribosomal sequences for this supermatrix, we developed a new program (TaxonomyAlign) to help perform taxonomy-guided alignments. The new combined matrix contained 5,242 anuran species with data from 307 markers, but with 95% missing data overall. This dataset represented a 71% increase in species sampled relative to the previous largest supermatrix analysis of anurans (adding 2,175 species). Maximum-likelihood analyses generated a tree in which higher-level relationships (and estimated clade ages) were generally concordant with those from phylogenomic analyses but were more discordant with the previous largest supermatrix analysis. We found few obvious problems arising from the extensive missing data in most species. We also generated a set of 100 time-calibrated trees for use in comparative analyses. Overall, we provide an improved estimate of anuran phylogeny based on the largest number of combined taxa and markers to date. More broadly, we demonstrate the potential to combine phylogenomic and supermatrix analyses in other groups of organisms.

Adenosinergic System and Neuroendocrine Syncope: What Is the Link?

Although very common, the precise mechanisms that explain the symptomatology of neuroendocrine syncope (NES) remain poorly understood. This disease, which can be very incapacitating, manifests itself as a drop in blood pressure secondary to vasodilation and/or extreme slowing of heart rate. As studies continue, the involvement of the adenosinergic system is becoming increasingly evident. Adenosine, which is an ATP derivative, may be involved in a large number of cases. Adenosine acts on G protein-coupled receptors with seven transmembrane domains. A1 and A2A adenosine receptor dysfunction seem to be particularly implicated since the activation leads to severe bradycardia or vasodilation, respectively, two cardinal symptoms of NES. This mini-review aims to shed light on the links between dysfunction of the adenosinergic system and NHS. In particular, signal transduction pathways through the modulation of cAMP production and ion channels in relation to effects on the cardiovascular system are addressed. A better understanding of these mechanisms could guide the pharmacological development of new therapeutic approaches.

Impact of 2,4-D and glyphosate-based herbicides on morphofunctional and biochemical markers in Scinax squalirostris tadpoles (Anura, Hylidae).

Understanding the effects of pesticides on non-target organisms is essential to assess the impact of these xenobiotics on the environment, allowing for a more informative and safer usage. The present study sought to evaluate the response of Scinax squalirostris tadpoles when exposed to different concentrations of two herbicides, DEZ® (i.e., dichlorophenoxyacetic acid or 2,4-D) and Roundup® Original (i.e., glyphosate). We collected 140 tadpoles between Gosner's 25 and 34 stages in a preservation area of the South American jelly palm Butia odorata. The animals were separated into eight groups and maintained in aquariums: acclimatization control (17 days), exposure control (24 days), and six exposure groups (7 days), including three concentration groups of each pesticide (4 µg/L, 15 µg/L, and 30 µg/L 2,4-D acid equivalent; 65 µg/L, 250 µg/L, and 500 µg/L glyphosate acid equivalent). Markers of body condition (length, body mass, K and Kn index) and oxidative balance (superoxide dismutase, catalase, glutathione S-transferase, TBARS, and carbonyl proteins) were analyzed. After 24 days (17 days of acclimation plus 7 days of exposure), tadpoles exposed to 15 µg/L of 2,4-D and 65 µg/L of glyphosate grew at higher than expected concentrations. They also had less lipoperoxidation than control tadpoles and higher superoxide dismutase, catalase, and glutathione S-transferase activity, specifically at the highest herbicide concentrations (2,4-D: 30 µg/L; glyphosate: 500 µg/L of glyphosate). Only the highest concentration of 2,4-D determined an increase in the levels of carbonyl proteins, indicating oxidative damage induced. DEZ® required more antioxidant defenses and induced a concentration-dependent answer of carbonylated proteins, suggesting oxidative stress and more toxic potential. These results may help government agencies make more conscious decisions regarding the usage of these chemicals and consider a balance between the conservation of amphibian species and agribusiness economic sustenance.

Deteriorating waterways: The effect of nitrate pollution on the development and physiology of the endangered southern bell frog (Litoria raniformis).

Nitrogen-based fertilizers can increase agricultural yields and crop quality, but this comes at the risk of contaminating nearby waterways. Nitrate is the most stable and abundant form of inorganic nitrogen in the environment and chronic exposure can impair performance and fitness in aquatically respiring species. But it remains unknown if these impairments are linked to disruptions in energy homeostasis. Here, we investigated the energetic cost of living in nitrate contaminated waters during early, energy-limited, larval life stages in the endangered southern bell frog (Litoria raniformis). We hypothesised that chronic nitrate exposure during development would increase energetic costs, evidenced by reductions in growth rates and body sizes, and elevations in routine heart rate (RHR) and routine metabolic rate (RMR). Following hatching, larvae were exposed to one of three nitrate treatments (0, 25 and 50 mg NO3-L-1) for 12 weeks, and survival, growth, RHR, and RMR were measured. Survival rates were similar across all treatments. Nitrate exposure caused a reduction in growth rates, resulting in larvae with significantly smaller body sizes. Compared to controls, nitrate-exposed larvae were 12% and 18% smaller in total length in the 25 and 50 mgNO3-L-1 treatments, respectively. However, RHR and RMR were independent of nitrate exposure, indicating that the 'cost of living' was similar across treatments. Observed growth reductions were therefore independent of RHR and RMR, suggesting other mechanisms were involved. Taken together, these results highlight the vulnerability of L. raniformis to nitrate during early life and suggest that the application of nitrogen-based fertilizers near critical aquatic habitats will be harmful.

From tadpole to adult frog locomotion.

The transition from larval to adult locomotion in the anuran, Xenopus laevis, involves a dramatic switch from axial to appendicular swimming including intermediate stages when the tail and hindlimbs co-exist and contribute to propulsion. Hatchling tadpole swimming is generated by an axial central pattern generator (CPG) which matures rapidly during early larval life. During metamorphosis, the developing limbs are controlled by a de novo appendicular CPG driven initially by the axial system before segregating to allow both systems to operate together or independently. Neuromodulation plays important roles throughout, but key modulators switch their effects from early inhibitory influences to facilitating locomotion. Temperature affects the construction and operation of locomotor networks and global changes in environmental temperature place aquatic poikilotherms, like amphibians, at risk. The locomotor control strategy of anurans differs from other amphibian groups such as salamanders, where evolution has acted upon the thyroid hormone pathway to sculpt different developmental outcomes.

Skin bacterial community differences among three species of co-occurring Ranid frogs.

Skin microbial communities are an essential part of host health and can play a role in mitigating disease. Host and environmental factors can shape and alter these microbial communities and, therefore, we need to understand to what extent these factors influence microbial communities and how this can impact disease dynamics. Microbial communities have been studied in amphibian systems due to skin microbial communities providing some resistance to the amphibian chytrid fungus, Batrachochytrium dendrobatidis. However, we are only starting to understand how host and environmental factors shape these communities for amphibians. In this study, we examined whether amphibian skin bacterial communities differ among host species, host infection status, host developmental stage, and host habitat. We collected skin swabs from tadpoles and adults of three Ranid frog species (Lithobates spp.) at the Mianus River Gorge Preserve in Bedford, New York, USA, and used 16S rRNA gene amplicon sequencing to determine bacterial community composition. Our analysis suggests amphibian skin bacterial communities change across host developmental stages, as has been documented previously. Additionally, we found that skin bacterial communities differed among Ranid species, with skin communities on the host species captured in streams or bogs differing from the communities of the species captured on land. Thus, habitat use of different species may drive differences in host-associated microbial communities for closely-related host species.

Background matching through fast and reversible melanin-based pigmentation plasticity in tadpoles comes with morphological and antioxidant changes.

Facultative colour change is widespread in the animal kingdom, and has been documented in many distantly related amphibians. However, experimental data testing the extent of facultative colour change, and associated physiological and morphological implications are comparatively scarce. Background matching in the face of spatial and temporal environmental variation is thought to be an important proximate function of colour change in aquatic amphibian larvae. This is particularly relevant for species with long larval periods such as the western spadefoot toad, Pelobates cultripes, whose tadpoles spend up to six months developing in temporary waterbodies with temporally variable vegetation. By rearing tadpoles on different coloured backgrounds, we show that P. cultripes larvae can regulate pigmentation to track fine-grained differences in background brightness, but not hue or saturation. We found that colour change is rapid, reversible, and primarily achieved through changes in the quantity of eumelanin in the skin. We show that this increased eumelanin production and/or maintenance is also correlated with changes in morphology and oxidative stress, with more pigmented tadpoles growing larger tail fins and having an improved redox status.

Dark or light? Preference of anuran tadpoles to background illumination in response to food and predators.

Background illumination and its intensity are crucial factors in visual interaction among organisms. In the present study, we used tadpoles of eight sympatric anuran species (Duttaphrynus melanostictus, Microhyla ornata, Uperodon globulosus, Kaloula taprobanica, Euphlyctis cyanophlyctis, Fejervarya orissaensis, Polypedates maculatus, and Polypedates teraiensis) to examine species-specific responses towards background illumination (shade and light), combined with four treatments [without food and predator (F-P-), with food and without predator (F+P-), without food and with predator (F-P+), and with food and with predator (F+P+)], with four coloured backgrounds (green, red, brown, and black) during different hours of a day (early morning, late morning, noon, and afternoon). Anuran tadpoles choose shaded sides over lighter sides, as such microhabitats are used as an effective means of camouflage, but most of the M. ornata tadpoles preferred the opposite. The observations were similar for red, green, and brown backgrounds simulating different natural conditions. The developmental stage and co-occurrence of tadpoles of multiple species do not affect their behavioural responses. These results draw attention to the importance of low illuminated/shaded backgrounds for behavioural responses of anuran tadpoles to environmental changes.