Poison Frog Research Articles

Food poisoning causes and prevention and what to know about hygiene

Food-borne diseases are the most common health problems globally, and they are particularly common in Third World countries like India due to poor public sanitation and hygiene. Broadly speaking, food poisoning refers to any illness brought on by eating food that contains bacteria or non-bacterial substances. Stated differently, it's an acute instance of gastroenteritis caused by ingesting chemicals-contaminated food or drink, animal or plant-derived poisons, or living microbes and their toxins. Acute gastroenteritis is one of the leading causes of morbidity and mortality. The most vulnerable are newborns and young children. The clinical symptoms of a foodborne infection are determined by the pathogenic mechanisms that underlie it. The main symptoms are headache, nervousness, intense thirst, abrupt vomiting, diarrhea, colicky discomfort, cold, clammy skin, slow heartbeat, rigours, and cramps. The provision of clean, drinkable water, appropriate disposal of human and animal sewage with isolation from water supplies, and fundamental food hygiene standards are all very effective ways to prevent the development of these disorders.

Anisakid larvae in the skipjack tuna Katsuwonus pelamis captured in Japanese waters: Two-year monitoring of infection levels after the outbreak of human anisakiasis in 2018

In 2018, human anisakiasis caused by the ingestion of the skipjack tuna Katsuwonus pelamis occurred frequently in Japan. This may be attributable to a heavy infection of A. simplex (s.s.) in the host's muscle tissue. In this study, we investigate infection levels of anisakid L3 larvae in skipjack tuna captured in Japanese waters afterward (2019–2020) to contribute to predict and prevent the outbreak of human anisakiasis. A total of 476 larvae were detected from 78 out of 85 skipjack tuna captured at 14 stations of the Pacific and East China Sea. The present parasitological survey suggests that infection levels in 2019–2020 were low, comparing that in 2018; in total only seven larvae were found from the host's muscle tissue. The collected larvae were identified by molecular methods to Anisakis berlandi, A. pegreffii, A. simplex (s.s.), A. typica and Skrjabinisakis physeteris (s.l.). Not only larvae of A. simplex (s.s.) but also those of A. berlandi were found from the muscle tissue and thus the latter species may also be a causative agent of human anisakiasis. In addition, this study confirmed the geographic distribution pattern that A. simplex (s.s.) is abundant in the Pacific, while A. pegreffii is dominant in the East China Sea. Our results contribute to understanding the risk of food poisoning and stock delimitation of host animals.

Sexy fingers: Pheromones in the glands of male dendrobatid frogs.

Many animals exchange chemicals during courtship and mating. In some amphibians, sexual chemical communication is mediated by pheromones produced in male breeding glands that are transferred to the female's nostrils during mating. This has been mostly studied in salamanders, despite frogs having similar glands and courtship behaviours suggestive of chemical communication. In Neotropical poison frogs (Dendrobatidae and Aromobatidae), males of many species develop breeding glands in their fingers, causing certain fingers to visibly swell. Many also engage in cephalic amplexus, whereby the male's swollen fingers are placed in close contact with the female's nares during courtship. Here, we investigate the possible roles of swollen fingers in pheromone production using whole-transcriptome sequencing (RNAseq). We examined differential gene expression in the swollen versus non-swollen fingers and toes of two dendrobatid species, Leucostethus brachistriatus and Epipedobates anthonyi, both of which have specialised mucous glands in finger IV, the latter of which has cephalic amplexus. The overwhelming pattern of gene expression in both species was strong upregulation of sodefrin precursor-like factors (SPFs) in swollen fingers, a well-known pheromone system in salamanders. The differentially expressed SPF transcripts in each species were very high (>40), suggesting a high abundance of putative protein pheromones in both species. Overall, the high expression of SPFs in the swollen fingers in both species, combined with cephalic amplexus, supports the hypothesis that these traits, widespread across members of the subfamilies Colostethinae and Hyloxalinae (ca. 141 species), are involved in chemical signalling during courtship.

Odor cues rather than personality affect tadpole deposition in a neotropical poison frog.

Animals constantly need to evaluate available external and internal information to make appropriate decisions. Identifying, assessing, and acting on relevant cues in contexts such as mate choice, intra-sexual competition, and parental care is particularly important for optimizing individual reproductive success. Several factors can influence decision-making, such as external environmental cues and the animal's own internal state, yet, we have limited knowledge on how animals integrate available information. Here, we used an entire island population (57 males, 53 females, and 1,109 tadpoles) of the neotropical brilliant-thighed poison frog Allobates femoralis to investigate how 2 factors (olfactory cues and personality traits) influence the ability of males to find and use new resources for tadpole deposition. We experimentally manipulated the location of tadpole deposition sites and their associated olfactory cues, and repeatedly measured exploration and boldness in adult males. We further reconstructed tadpole deposition choices via inferred parent-offspring relationships of adult frogs and tadpoles deposited in our experimental pools using molecular parentage analysis. We found that the discovery and use of new rearing sites were heavily influenced by olfactory cues; however, we did not find an effect of the measured behavioral traits on resource discovery and use. We conclude that in highly dynamic environments such as tropical rainforests, reliable external cues likely take priority over personality traits, helping individuals to discover and make use of reproductive resources.

Physiological state matching in a pair bonded poison frog.

More than a century ago, Charles Darwin hypothesized that theempathy-like phenotype is a phylogenetically widespread phenomenon. This idea remains contentious, due to the challenges of empirically examining emotions, and few investigations among non-mammalian vertebrates. We provide support for Darwin's hypothesis by discovering partial evidence for the most ancestral form of empathy, emotional contagion (i.e. matching another individual's emotional state), in the pair bonding mimetic poison frog, Ranitomeya imitator. We found that male corticosterone, a physiological biomarker of stress, positively correlates with female partners in experimental and semi-natural conditions. This does not appear to coincide with behavioural state-matching. However, it is specific to female partners relative to familiar female non-partners, and is independent of effects that commonly confound studies on emotional contagion. Furthermore, this physiological state-matching is irrespective of partnership longevity or lifetime reproductive output. These results physiologically indicate socially selective emotional contagion in a monogamous amphibian, and paradigms that elicit coinciding neural and behavioural indicators and morphogenic co-variation are needed for further corroboration. Further studies on ancestral forms of empathy in non-mammalian vertebrates are warranted.

Can sustainable biocommerce continue to support conservation, or will the captive breeding of offspring be its Achilles heel?

Abstract The trade in high‐value natural resources, particularly exotic plants and animals (henceforth biocommerce), can lead to both positive and negative impacts on wild populations. The exotic plant and animal hobbies are highly organized with internal cultures that are often poorly understood by non‐members; however, understanding them is of central importance for biocommerce with both direct and indirect consequences for the conservation of wild populations. Growing international demands for exotic species leaves simple questions related to the economics of biocommerce unexplored. The long‐term success of biocommerce businesses requires constant income, meaning they obtain and retain significant market proportions. Some biocommerce products can be reproduced by hobbyists and undercut business efforts based on sustainably produced exports. We analyse a test case in Neotropical poison frogs where sustainable biocommerce is burgeoning, yet (export‐based) businesses face direct market competition from the offspring produced within the countries, which receive their exports, and therefore are forced to rely on fervent customer support. Solution: We survey customers' behaviours where we find different classes of consumers, which differ in where they place higher values within the hobby. By taking into account these different classes, we gain insights and potential solutions to promote the stability of this unique type of biocommerce.

What Makes a Mimic? Orange, Red, and Black Color Production in the Mimic Poison Frog (Ranitomeya imitator).

Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and reproduction. Aposematic colors and patterns are highly variable; however, the genetic, biochemical, and physiological mechanisms producing this conspicuous coloration remain largely unidentified. Here, we identify genes potentially affecting color variation in two color morphs of Ranitomeya imitator: the orange-banded Sauce and the redheaded Varadero morphs. We examine gene expression in black and orange skin patches from the Sauce morph and black and red skin patches from the Varadero morph. We identified genes differentially expressed between skin patches, including those that are involved in melanin synthesis (e.g. mlana, pmel, tyrp1), iridophore development (e.g. paics, ppat, ak1), pteridine synthesis (e.g. gch1, pax3-a, xdh), and carotenoid metabolism (e.g. dgat2, rbp1, scarb2). In addition, using weighted correlation network analysis, we identified the top 50 genes with high connectivity from the most significant network associated with gene expression differences between color morphs. Of these 50 genes, 13 were known to be related to color production (gch1, gmps, gpr143, impdh1, mc1r, pax3-a, pax7, ppat, rab27a, rlbp1, tfec, trpm1, xdh).

Bromeliad-Dwelling Frogs Revealed by Citizen Scientists

Understanding species composition across temporal and spatial scales through participatory monitoring has contributed to the development of several studies focused on biodiversity in Neotropical ecosystems. Habitat loss and the illegal collection of bromeliads pose significant threats to bromeligenous frogs, which depend on the rainwater collected between bromeliad leaves for egg and tadpole development. In this study, we compiled a comprehensive dataset of bromeligenous frogs using data from “Projeto Bromélias” on the iNaturalist citizen science platform. Our dataset includes records of 85 species of bromeligenous frogs, representing 52% of the 164 known species that reproduce in bromeliads. These species belong to 33 genera and 10 families and are reported from 18 countries. Twenty-eight species are listed in threatened categories on a global scale. Our findings extended the known geographic distribution of four species. Notably, the green and black poison dart Frog, Dendrobates auratus, was recorded as a non-native species in Hawaii, USA. Regarding the temporal data, the number of bromeligenous records increased substantially after 2009. This study highlights the value of citizen science platforms as important tools for monitoring bromeliad inhabitants and contributing to management and conservation initiatives.

The genomics of mimicry: Gene expression throughout development provides insights into convergent and divergent phenotypes in a Müllerian mimicry system.

A common goal in evolutionary biology is to discern the mechanisms that produce the astounding diversity of morphologies seen across the tree of life. Aposematic species, those with a conspicuous phenotype coupled with some form of defence, are excellent models to understand the link between vivid colour pattern variations, the natural selection shaping it, and the underlying genetic mechanisms underpinning this variation. Mimicry systems in which species share a conspicuous phenotype can provide an even better model for understanding the mechanisms of colour production in aposematic species, especially if comimics have divergent evolutionary histories. Here we investigate the genetic mechanisms by which mimicry is produced in poison frogs. We assembled a 6.02-Gbp genome with a contig N50 of 310 Kbp, a scaffold N50 of 390 Kbp and 85% of expected tetrapod genes. We leveraged this genome to conduct gene expression analyses throughout development of four colour morphs of Ranitomeya imitator and two colour morphs from both R. fantastica and R. variabilis which R. imitator mimics. We identified a large number of pigmentation and patterning genes differentially expressed throughout development, many of them related to melanophores/melanin, iridophore development and guanine synthesis. We also identify the pteridine synthesis pathway (including genes such as qdpr and xdh) as a key driver of the variation in colour between morphs of these species, and identify several plausible candidates for colouration in vertebrates (e.g. cd36, ep-cadherin and perlwapin). Finally, we hypothesise that keratin genes (e.g. krt8) are important for producing different structural colours within these frogs.

An Ethnobotanical Study of Antidote Medicinal Plants in Kalkulam Taluk, Kanyakumari District

Ethnobotany is the field of science that deals with the association between plants and humans, the term implies the study of indigenous or traditional knowledge of plants. This ethnobotanical survey focused on prevalence of antidote medicinal plants and the traditional knowledge of that plants among the local people of Kalkulam taluk, Kanyakumari district. The information was collected from local communities. The antidote plant species that used for different types of poisons in the study area, were documented on the basis of identification of antidote plants. A total of 45 antidote medicinal plants, belonging to 25 families were collected and identified. Plant family with the highest antidote plants in the study area used for various types of poisons was Fabaceae (17%). The result of growth form analysis showed that Shrub constituted the highest proportion of antidote plants (34%), Roots (39%) were the most frequently utilized plant parts for preparation of traditional antidote remedies. Most of the antidote plants in the study area used for animal poison with the proportion of (92%). Decoction was a widely used method of preparation of traditional antidote remedies where oral administration 92% was the dominant route. The study revealed people of the Kalkulam area are well known about the antidote plants and mostly used for poisoning and post poisoning symptoms and also used as first aid therapy in poisoning cases. Keywords: Ethnobotany, Antidote, Medicinal plants, Poisons, Traditional remedies

Tadpoles rely on mechanosensory stimuli for communication when visual capabilities are poor

The ways in which animals sense the world changes throughout development. For example, young of many species have limited visual capabilities, but still make social decisions, likely based on information gathered through other sensory modalities. Poison frog tadpoles display complex social behaviors that have been suggested to rely on vision despite a century of research indicating tadpoles have poorly-developed visual systems relative to adults. Alternatively, other sensory modalities, such as the lateral line system, are functional at hatching in frogs and may guide social decisions while other sensory systems mature. Here, we examined development of the mechanosensory lateral line and visual systems in tadpoles of the mimic poison frog (Ranitomeya imitator) that use vibrational begging displays to stimulate egg feeding from their mothers. We found that tadpoles hatch with a fully developed lateral line system. While begging behavior increases with development, ablating the lateral line system inhibited begging in pre-metamorphic tadpoles, but not in metamorphic tadpoles. We also found that the increase in begging and decrease in reliance on the lateral line co-occurs with increased retinal neural activity and gene expression associated with eye development. Using the neural tracer neurobiotin, we found that axonal innervations from the eye to the brain proliferate during metamorphosis, with few retinotectal connections in recently-hatched tadpoles. We then tested visual function in a phototaxis assay and found tadpoles prefer darker environments. The strength of this preference increased with developmental stage, but eyes were not required for this behavior, possibly indicating a role for the pineal gland. Together, these data suggest that tadpoles rely on different sensory modalities for social interactions across development and that the development of sensory systems in socially complex poison frog tadpoles is similar to that of other frog species.

Early development of the glucocorticoid stress response in poison frog tadpoles.

The timing of HPA axis development differs across species. We studied the HPA axis across tadpole development in Dendrobates tinctorius . No difference in corticosterone concentration across development.No difference in corticosterone response to ACTH across development.Results suggest an early developed HPA axis is essential for their life history.

Adult poison dart frogs avoid potential heterospecific competitors using their sense of smell

AbstractOlfaction is the oldest sense in the animal kingdom. It is used during a multitude of behaviours, such as the encounter of food, the detection of predators, the recognition of habitat‐related cues or the communication with conspecifics. While the use of olfaction and chemical communication has been studied widely in some animals, it is barely known in others. Anurans (frogs and toads), for example, are well known to use acoustic and visual senses, but their chemical sense is still largely understudied. Studies concerning the chemical sense in anurans have been mostly based on the use of semiochemicals in juvenile stages, while the information on adult anurans remains limited. In this study, we analysed the behavioural response of the Neotropical poison frog Ranitomeya sirensis (Sira poison frog, Dendrobatidae) when presented with the odours of prey, novel/prey‐luring fruit, habitat, conspecific faeces and heterospecifics. For this, we offered each of the odours by placing them into one of two testing tubes fixed in an arena, with the other tube left empty as a control. We then measured the time the frogs spent in the vicinity of the odour versus the control tube and calculated a response index. While the frogs did not show a significant avoidance or attraction towards most of the tested odours, they showed a strong response towards the heterospecific odour, which was significantly avoided. This is the first evidence of a poison dart frog responding towards the odours of adult heterospecific frogs. We consider potential reasons for this strong negative reaction, such as the interspecific competition avoidance hypothesis, and discuss our results in the context of other animal species being deterred or attracted by heterospecific chemical cues.

Regulatory role of oxidative stress in retrorsine – Induced apoptosis and autophagy in primary rat hepatocytes

Pyrrolizidine alkaloids (PAs) are a group of naturally occurring alkaloids widely present in plants. PAs are highly hepatotoxic and have been documented to cause many incidents of human and animal poisoning. Retrorsine (RTS) is a pyrrolizidine alkaloid (PA) derived from the Compositae Senecio, which has been shown to cause hepatotoxicity. Human liver poisoning occurs through the consumption of RTS-contaminated food, and animals can also be poisoned by ingesting RTS-containing toxic plants. The mechanism of RTS-induced liver toxicity is not fully understood. In this study, we demonstrated that RTS-induced oxidative stress plays a pivotal role in RTS-induced liver toxicity involving apoptosis and autophagy. The results showed that RTS treatment in the cultured Primary rat hepatocytes caused cytotoxicity and release of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in a time- and dose-dependent manner. Our study showed that treatment of RTS induced ROS and MDA (malondialdehyde, a lipid peroxidation marker) in the hepatocytes, and reduced antioxidant capacity (GSH content, SOD activity), suggesting RTS treatment caused oxidative stress response in the hepatocytes. Furthermore, we found that RTS induced apoptosis and autophagy in the hepatocytes, and RTS-induced apoptosis and autophagy could be alleviated by ROS scavenger N-acetylcysteine (NAC) and the MAPK pathway inhibitors suggesting ROS/MAPK signaling pathway plays a role in RTS induced apoptosis and autophagy. Collectively, this study reveals the regulatory mechanism of oxidative stress in RTS-induced apoptosis and autophagy in the hepatocytes, providing important insights of molecular mechanisms of hepatotoxicity induced by RTS and related pyrrolizidine alkaloids in liver. This mechanism provides a basis for the prevention and treatment of PA poisoning in humans and animals.

Individual behavioral variability across time and contexts in Dendrobates tinctorius poison frogs

Individual behavioral variability across time and contexts in Dendrobates tinctorius poison frogs

Defensive alkaloid variation and palatability in sympatric poison frogs

Defensive alkaloid variation and palatability in sympatric poison frogs

Genome Assembly of the Dyeing Poison Frog Provides Insights into the Dynamics of Transposable Element and Genome-Size Evolution.

Genome size varies greatly across the tree of life and transposable elements are an important contributor to this variation. Among vertebrates, amphibians display the greatest variation in genome size, making them ideal models to explore the causes and consequences of genome size variation. However, high-quality genome assemblies for amphibians have, until recently, been rare. Here, we generate a high-quality genome assembly for the dyeing poison frog, Dendrobates tinctorius. We compare this assembly to publicly available frog genomes and find evidence for both large-scale conserved synteny and widespread rearrangements between frog lineages. Comparing conserved orthologs annotated in these genomes revealed a strong correlation between genome size and gene size. To explore the cause of gene-size variation, we quantified the location of transposable elements relative to gene features and find that the accumulation of transposable elements in introns has played an important role in the evolution of gene size in D. tinctorius, while estimates of insertion times suggest that many insertion events are recent and species-specific. Finally, we carry out population-scale mobile-element sequencing and show that the diversity and abundance of transposable elements in poison frog genomes can complicate genotyping from repetitive element sequence anchors. Our results show that transposable elements have clearly played an important role in the evolution of large genome size in D. tinctorius. Future studies are needed to fully understand the dynamics of transposable element evolution and to optimize primer or bait design for cost-effective population-level genotyping in species with large, repetitive genomes.

A One Health Approach to Mitigating Acute Pesticide Poisoning in Animals

This overview highlights the importance of adopting a one health approach to tackle the challenges associated with acute pesticide poisoning in animals. The interconnectedness of human, animal, and environmental health underscores the need of collaborative efforts. Swift veterinary care is crucial for immediate intervention, while ongoing monitoring and reporting help identify emerging threats and potential human health risks. This approach emphasizes a unified effort across disciplines to monitor, assess, regulate, educate, and respond to pesticide-related incidents. Surveillance and monitoring systems are foundational to this approach, amalgamating veterinary and human health data to discern trends and potential cross-species exposures. Emergency response plans are integral, ensuring coordinated efforts between veterinary and human health professionals in the event of pesticide poisoning incidents. Data sharing mechanisms and enhanced communication channels foster rapid response and information dissemination. Environmental conservation practices, such as habitat protection and sustainable agriculture, contribute to safeguarding ecosystems from pesticide-related harm. Community engagement is pivotal, encouraging local participation in surveillance and empowering communities to influence decisions regarding pesticide use. By fostering collaboration, promoting awareness, and integrating various expertise, this approach strives to protect the health of humans, animals, and the environment in the face of pesticide-related challenges.

Toxic to the touch: The makings of lethal mantles in pitohui birds and poison dart frogs.

How do chemically defended animals resist their own toxins? This intriguing question on the concept of autotoxicity is at the heart of how species interactions evolve. In this issue of Molecular Ecology (Molecular Ecology, 2024, 33), Bodawatta and colleagues report on how Papua New Guinean birds coopted deadly neurotoxins to create lethal mantles that protect against predators and parasites. Combining chemical screening of the plumage of a diverse collection of passerine birds with genome sequencing, the researchers unlocked a deeper understanding of how some birds sequester deadly batrachotoxin (BTX) from their food without poisoning themselves. They identified that birds impervious to BTX bear amino acid substitutions in the toxin-binding site of the voltage-gated sodium channel Nav1.4, whose function is essential for proper contraction and relaxation of vertebrate muscles. Comparative genetic and molecular docking analyses show that several of the substitutions associated with insensitivity to BTX may have become prevalent among toxic birds through positive selection. Intriguingly, poison dart frogs that also co-opted BTX in their lethal mantles were found to harbour similar toxin insensitivity substitutions in their Nav1.4 channels. Taken together, this sets up a powerful model system for studying the mechanisms behind convergent molecular evolution and how it may drive biological diversity.

Tap dancing frogs: Posterior toe tapping and feeding in Dendrobates tinctorius

AbstractAnimals have myriad adaptations to help them hunt and feed in the most efficient and effective manner. One mysterious behavior related to hunting and feeding is the posterior toe tapping behavior of some frogs. Biologists and hobbyists alike have long noticed this behavior, but there is little empirical data to explain its causes and consequences. To test the hypothesis that tapping is related to feeding and modulated by environmental context, we conducted a series of related experiments in the Dyeing poison frog, Dendrobates tinctorius. We first confirmed that tap rate was higher during feeding as has been observed in other species. Interestingly, this effect was heightened in the presence of a conspecific. We next asked whether frogs tapped less under conditions when prey were visible, but inaccessible. Finally, we asked whether D. tinctorius adjusted tap rate based on substrate characteristics and whether prey capture success was higher when tapping. In addition to confirming an association between tapping and feeding, our work demonstrates modulation of toe tapping based on social context, prey accessibility, and substrate characteristics. Based on our findings, we suggest that tapping could act to induce prey movement and thereby facilitate prey detection and capture by frogs.