Poison Frog Research Articles

Demographic Responses in a Population of the Strawberry Poison Frog (Oophaga pumilio) after Resource Manipulations

Demographic Responses in a Population of the Strawberry Poison Frog (Oophaga pumilio) after Resource Manipulations

Formal Total Synthesis of Batrachotoxin Enabled by Radical and Weix Coupling Reactions.

Batrachotoxin (1), originally isolated from a Columbian poison-dart frog, is a steroidal alkaloid. Its 6/6/6/5-membered carbocycle (ABCD-ring) contains two double bonds, one nitrogen, and five oxygen functionalities. We developed a radical-based convergent strategy and realized the total synthesis of 1 in 28 steps. The AB-ring and D-ring fragments were efficiently synthesized and linked by exploiting a powerful Et3B/O2-mediated radical coupling reaction. Vinyl triflate and vinyl bromide were then utilized for a Pd/Ni-promoted Weix coupling reaction to cyclize the C-ring. A hydroxy group of the C-ring was stereoselectively installed by a decarboxylative hydroxylation reaction to prepare an advanced intermediate of our previous total synthesis of 1.

Intraspecific divergence of sexual size dimorphism and reproductive strategies in a polytypic poison frog

AbstractIntraspecific variation in body size, both among populations and between sexes, is an important factor influencing life-history strategies. This variation might be the response to different environmental conditions, as well as natural and sexual selection, and can result in differences in behavior and reproductive strategies among populations. Here, we use the dyeing poison frog (Dendrobates tinctorius) as a model to investigate how interpopulation variation in body size and sexual size dimorphism affects reproductive strategies. As body size increased, sexual size dimorphism also increased, i.e., females were larger than males, and more so in populations with overall larger frogs. This indicates that there is a stronger selection for body size in females than in males, likely as a response to divergent reproductive investment between the sexes. Females from larger-bodied populations produced larger clutches, but the overall number of froglets produced per clutch did not differ among populations. We discuss potential causes and mechanisms that might be responsible for the observed divergence in body size, sexual size dimorphism, and reproductive strategies among populations that likely represent local adaptations. Our findings demonstrate the importance of cross-population studies, cautioning against drawing general conclusions about a species’ ecology without accounting for intraspecific variation.

Stiff-legged behaviour in the green and black poison frog Dendrobates auratus in response to simulated predation

Stiff-legged behaviour in the green and black poison frog Dendrobates auratus in response to simulated predation

Conspicuous and cryptic poison frogs are picky and prefer different meals in syntopy

Conspicuous and cryptic poison frogs are picky and prefer different meals in syntopy

Assessing of Physicochemical Parameters and Seasonal Variations in the Tinau River of Palpa, Nepal

The water quality and quantity parameters in lakes, rivers, marshes and lagoons are affected from both natural factors and human activities. The present study was undertaken to assess the quality of water samples with special reference to physicochemical properties of Tinau River. The water samples were collected from November 2021 to September, 2022 and analysed 17 physico-chemical parameters (Temperature, PH, dissolved oxygen, free CO2, total alkalinity, hardness, turbidity, Ammonia, Nitrogen, Chlorine, Chromium, Copper, Cyanide, Iron, Nitrate nitrogen, Phosphorus, Silica and Sulphide). The result physic-chemical parameters show that turbidity of water is with slightly basic property with PH 8, temperature between16-17°C, DO (9-10.1mg/L), Total alkalinity (65-98mg/l), Hardness (4.8-10.5mg/l), Free CO2 (3-4), Ammonia nitrate trace and other components are negative. This showed that research area are good to excellent quality water for different purposes. In addition, for the purpose of maintaining water quality, it is essential to understand specifics about many physico-chemical properties. These factors need additional study because they can induce water poisoning or chronic poisoning in aquatic animals.

An amphibian toxin phenotype is sexually dimorphic and shows seasonal concordant change between sexes

Sexually dimorphic phenotypes are consequential to animal survival, and this is especially apparent with defense phenotypes. Amphibians have poison glands, and several lineages maintain a neurotoxin, tetrodotoxin (TTX), which is largely considered a derived chemical defense trait. However, production pathways are unclear, and, as such, whether males and females differentially produce or appropriate toxin concentrations is not known. We evaluated the relationship between TTX concentrations, sex, and morphology by collecting trait data from more than 850 wild newts of the genus Taricha and tested for sex-based differences, potential sex-based changes to the phenotype between breeding seasons, and factors influencing toxicity. Females, regardless of reproductive status, exhibited greater concentrations than males, and temporal patterns indicate male and female trait values tend to fluctuate concordantly at short time scales, with females showing greater change over time. Tree regression results underscored the importance of size and sex to the phenotype. Sexual dimorphism and plasticity of toxins broaden the ecological roles of animal poisons beyond defense only and should recast how we model the evolution of tetrodotoxin.

Eating to the beat of the drum: vibrational parameters of toe tapping behavior in Dendrobates truncatus (Anura: Dendrobatidae)

Toe tapping is performed by certain anuran species while foraging for their prey. This behavior has been described in different frog families, with some hypotheses regarding its function, including predator-prey communication, still unverified. To understand the function of toe tapping and its potential relationship with foraging in anurans, the present research focuses on descriptive analysis of vibrational parameters of toe tapping produced during foraging in the poison dart frog Dendrobates truncatus. We implemented an experimentally designed arena that allowed us to record toe tapping vibrations using an accelerometer attached to an artificial substrate. Continuous recordings of toe tapping were obtained from 19 individuals, enabling us to identify and define the vibrational parameters, with reference to the time between attacks on prey. The average tap duration was 0.06 ± 0.01 s with an inter-tap interval of 0.15 ± 0.07 s. We also identified a pattern, displayed in 36.5% of the analyzed attacks, of progressive acceleration of toe tapping before an attack. Furthermore, we found that individuals with longer third toes were more likely to accelerate their taps. Lastly, we found no evidence of sexual dimorphism in the toe tapping behavior of Dendrobates truncatus. Describing the vibrational parameters of toe tapping in Dendrobates truncatus represents a new frontier of research in the field of foraging behavior and paves the way for hypothesis testing regarding its functionality.

The study of acute and subchronic oral toxicity of medicinal drug «Enrocolitrim» on laboratory animals

Relevance. The results of the study of the oral toxicity of the medicinal product for veterinary use «Enrocolitrim» on laboratory rodents are presented. Studies of acute toxicity in mice and rats with the determination of the hazard class are described, as well as data on the study of subchronic toxicity of the drug for 14 days in laboratory rats are presented.Methods. To determine the acute toxicity of the drug, 36 outbred rats and 50 outbred mice were used. «Enrocolytrim» was administered using an intragastric tube at doses that allow revealing a dose-dependent effect to assess LD50. Toxicity parameters were calculated according to the method of Kerber, Miller and Teintner, the nature and severity of signs of animal intoxication were visually assessed for 14 days. In a subchronic experiment, the study drug «Enrokolitrim» was studied on 40 outbred rats, of which 3 experimental and 1 control groups were formed. During the experiment, the rodents were weighed, signs of intoxication were recorded, and blood samples were taken for morphological and biochemical analyzes. Dead and euthanized animals were subjected to autopsy.Results. The obtained LD50 values with a single oral administration of the drug «Enrocolitrim» to rats and mice allowed it to be assigned the 4th hazard class – lowh–azard substances (GOST 12.1.007-76). In a subchronic 14-day experiment on rats, it was found that the dose of «Enrocolitrim» 1243 mg/kg with intragastric administration is toxic, and doses of 621.5 mg/kg and 248.6 mg/kg are inactive (safe).

Water-borne testosterone levels predict exploratory tendency in male poison frogs

Hormones play a fundamental role in mediating social behaviors of animals. However, it is less well understood to what extent behavioral variation between individuals can be attributed to variation in underlying hormonal profiles. The goal of the present study was to infer if individual androgen levels, and/or the modulation thereof, can explain among-individual variation in aggressiveness, boldness and exploration. We used as a model the dart-poison frog Allobates femoralis and took repeated non-invasive water-borne hormonal samples of individual males before (baseline) and after (experimental) a series of behavioral tests for assessing aggression, boldness, and exploratory tendency. Our results show that androgen levels in A. femoralis are quite stable across the reproductive season. Repeatability in wbT baseline levels was high, while time of day, age of the frog, and trial order did not show any significant impact on measured wbT levels. In general, experimental wbT levels after behavioral tests were lower compared to the respective baseline levels. However, we identified two different patterns with regard to androgen modulation in response to behavioral testing: individuals with low baseline wbT tended to have increased wbT levels after the behavioral testing, while individuals with comparatively high baseline wbT levels rather showed a decrease in hormonal levels after testing. Our results also suggest that baseline wbT levels are linked to the personality trait exploration, and that androgen modulation is linked to boldness in A. femoralis males. These results show that differences in hormonal profiles and/or hormonal modulation in response to social challenges can indeed explain among-individual differences in behavioral traits.

Risk Assessment and Risk Management of Incidents of Suspected Poisoning

Abstract Poisoning in livestock, horses and wildlife may be localised or large events involving single or multiple animals and can have public health, economic or medicolegal, as well as animal welfare, implications. Investigation of these incidents is required to determine the cause, assess the risk to other animals and people and instigate an appropriate risk management plan. Investigations will involve clinical examination and history taking, site visits to determine possible sources of poisoning, post-mortem examination and collection of biological (both ante and post-mortem) and environmental samples (water, soil, feed, suspect plants). Interpretation of laboratory analyses and investigations may involve a multidisciplinary team in order to formulate and implement a risk management programme. Specialist advice should be sought early in the investigation in order to ensure appropriate sampling and correct actions are undertaken. Practitioners should be aware of where and how to report incidents, where to seek advice and have some awareness of common toxicological risks, particularly local or seasonal risks, to livestock and other animals. This case study outlines some of the steps that should be undertaken when handling a case of suspected poisoning in animals and highlights some of the possible circumstances and substances that may result in toxicosis. Information © The Author 2023

Влияние гепатопротекторного фитокомплекса на выраженность эндогенной интоксикации у лабораторных крыс при экспериментальной патологии печени, вызванной гидразином

Abstract. The purpose is to study the influence of the hepatoprotective phytocomplex on the severity of endogenous intoxication in laboratory rats with experimental liver pathology caused by hydrazine. Methods. The studies were carried out on non-linear rats, formed into 3 groups (n = 10). Toxic damage to the liver in rats of groups 1 and 2 was modeled by a single intragastric administration of hydrazine at a dose of 200 mg/kg of body weight. Immediately after intoxication and for the next three weeks in 1st group, the drug fitosomin was used – daily orally in the form of boluses at a dose of 0.5 g/kg of body weight, 2nd group after intoxication received empty cereal boluses, 3rd group was intact. In dynamics, the degree of endogenous intoxication was studied by the concentration of medium mass molecules (MMM) in the blood of animals at λ = 254 and 280 nm. Scientific novelty. Experimentally new data on the pharmacological effects of the hepatoprotective phytocomplex was obtained, which includes lecithin, dihydroquercetin, extracts of milk thistle, agrimony and golden boletus. For the first time, the effectiveness of the drug fitosomin was determined to reduce the severity of the endogenous intoxication syndrome in laboratory rats with experimental liver pathology caused by hydrazine. Results. It has been determined that hydrazine-induced liver pathology in laboratory rats is accompanied by the development of endogenous intoxication syndrome with a more pronounced increase in the blood fraction of MMM 254 relative to MMM 280. The use of fitosomin leads to a weakening of the toxic effect of hydrazine both on the liver and on the body of animals as a whole. The course application of the hepatoprotective phytocomplex increases the survival rate of rats, improves their clinical condition and leads to a decrease in the concentration of MMM in the blood. The obtained results outlined the prospects for the use of the drug fitosomin in veterinary practice in case of liver damage, as well as intoxication of animals.

Evaluation of anticoagulant rodenticide sensitivity by examining in vivo and in vitro responses in avian species, focusing on raptors

Anticoagulant rodenticides (ARs) are used to control pest rodent species but can result in secondary poisoning of non-target animals, especially raptors. In the present study, differences in AR sensitivity among avian species were evaluated by comparing in vivo warfarin pharmacokinetics and effects, measuring cytochrome P450s (CYPs) expression involved in AR metabolism, and conducting in vitro inhibition assays of the AR target enzyme Vitamin K 2,3-epoxide reductase (VKOR). Oral administration of warfarin at 4 mg/kg body weight did not prolong prothrombin time in chickens (Gallus gallus), rock pigeons (Columba livia), or Eastern buzzards (Buteo japonicus). Rock pigeons and buzzards exhibited shorter plasma half-life of warfarin compared to chickens. For the metabolite analysis, 4′-hydroxywarfarin was predominantly detected in all birds, while 10-hydroxywarfarin was only found in pigeons and raptors, indicating interspecific differences in AR metabolism among birds likely due to differential expression of CYP enzymes involved in the metabolism of ARs and variation of VKOR activities among these avian species. The present findings, and results of our earlier investigations, demonstrate pronounced differences in AR sensitivity and pharmacokinetics among bird species, and in particular raptors. While ecological risk assessment and mitigation efforts for ARs have been extensive, AR exposure and adverse effects in predatory and scavenging wildlife continues. Toxicokinetic and toxicodynamic data will assist in such risk assessments and mitigation efforts.

Antagonistic effects of N-acetylcysteine on lead-induced apoptosis and oxidative stress in chicken embryo fibroblast cells

Lead (Pb) is a heavy metal that can have harmful effects on the environment, which has severe cytotoxicity in many animal tissues. N-acetylcysteine (NAC) has antioxidant activity, reducing lead-induced oxidative stress and apoptosis, but its role in chicken cells is unknown. The current study explored the antagonistic effect of NAC on lead-induced apoptosis and oxidative stress in chicken embryo fibroblast (CEF). In this study, CEF was used as a model to measure the cytotoxic effects of lead nitrate at different concentrations, demonstrating a dose-dependent effect on CEF activity. Employing inverted microscopy, the investigation of morphological alterations in CEF cells was conducted. Fluorescence staining methodology enabled the assessment of reactive oxygen species (ROS) levels within CEF cells. Moreover, an enzyme-linked immunosorbent assay was utilized to detect the presence of oxidative damage indicators encompassing superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) activity, malondialdehyde (MDA) content, and total antioxidant capacity (T-AOC) within CEF cells. Furthermore, the determination of the apoptosis rate of CEF cells was accomplished through the utilization of the Hoechst 33258 staining method in combination with the Annexin V-FITC dual staining method. By using RT-qPCR for detection, lead treatment increased expression of pro-apoptotic genes, caspase-3, and caspase-9, and reduced expression of anti-apoptotic genes, Bcl-2, and BI-1. Reduced antioxidant capacity was shown by increased ROS and MDA levels in CEF cells after lead treatment. The results showed that NAC inhibited the expression of caspase-3 and caspase-9 in lead-treated CEF cells, while NAC had a certain inhibitory effect on the relative expression of Bcl-2 and BI-1 mRNA in lead-induced CEF cells. NAC significantly reduced lead-induced oxidative damage and apoptosis. Overall, our results demonstrate a novel protective effect of NAC against lead-induced injury in chicken cells, providing a theoretical basis for future investigations of drugs that are effective in preventing lead poisoning in animals.

Study on occurrence of agrochemical poisoning in Bovines at veterinary clinics of Udgir

In view of unavailability of data on agrochemical poisoning in livestock animals in India, the present work was conducted with objective to study the epidemiological aspects of agrochemical poisoning in bovines over a period of five years. A total of 98 cases of pesticide poisoning in bovines have been reported during 2016-2020 at Veterinary Clinical Complex, College of Veterinary and Animal Sciences, Udgir with hospital prevalence of 0.39%. Among various agrochemicals, insecticide poisoning was responsible for 45.91% cases, fungicide for 17.34%, herbicides for 16.32%, unknown pesticides for 10.20%, fertilizers for 7.14% and rodenticides for 3.06% cases of poisoning in bovines. Year-wise higher number of cases were reported during 2016 (30.61%) followed by 2017, 2019 (19.38% each) and 2018 (18.36%) while, month- wise highest number of poisoning cases were reported in months of November (14.28%), December (13.26%), July and September, October (11.22% each). Season-wise highest occurrence of poisoning was observed during monsoon and post-monsoon seasons while least occurrence was observed during summer season. Age-wise highest occurrence of agrochemical poisoning was reported in 4-6 year and 0-2 year age-group animals. Species-wise occurrence of poisoning revealed highest occurrence in cattle (65.31%) than buffaloes (34.69%). Among cattle 67.18% male animals while 32.82% female animals were affected. All buffaloes confirmed for poisoning were female. The findings of the present study will be helpful for formulating strategies to reduce exposure of livestock animals to agrochemicals.

The Future of Cyanobacteria Toxicity in Estuaries Undergoing Pulsed Nutrient Inputs: A Case Study from Coastal Louisiana

Harmful cyanobacteria blooms (cyanoHABs) are a global phenomenon, especially in calm, warm, and nutrient-rich freshwater and estuarine systems. These blooms can produce various potent toxins responsible for animal poisoning and human health problems. Nutrient-rich freshwater pulsed into estuaries affects turbidity, water temperature, salinity, and nutrient concentrations and ratios at irregular intervals, creating a highly dynamic habitat. However, the underlying processes that lead to the selective development of cyanoHABs for certain species and the fate of their toxins are still uncertain. This paper draws upon the rich body of research available for one such system, the Lake Pontchartrain Estuary, Louisiana, to generate insights about future research directions in pulsed-nutrient-delivery estuaries. Toxin-producing cyanobacteria blooms in river-dominated Louisiana coastal ecosystems have already been documented at high concentrations, presenting a potential risk to human health as $2.4 billion worth of Louisiana’s fish and shellfish are consumed by millions of people throughout the US every year. Recent studies have shown that the Lake Pontchartrain Estuary, just north of New Orleans, Louisiana has been experiencing cyanoHABs, likely connected to combinations of (a) high interannual variability in nutrient loading associated with seasonal and episodic rainfall, (b) the timing, duration, and magnitude of the flood-stage Mississippi River water diverted into the Lake Pontchartrain Estuary, and (c) saltwater inputs from tropical storms. It is expected that cyanoHABs will become more frequent in Louisiana with a warming climate and changes to the timing and magnitude of river water diverted into the Lake Pontchartrain Estuary, which will play a dominant role in the development of blooms in this region. More studies are needed to focus on the environmental conditions that control the succession or/and co-existence of different cyanobacteria species and their toxins, optimally culminating in a near-term forecasting tool since this information is critical for health agencies to mitigate or to provide early warnings. Toxin forecasts for pulsed-nutrient estuaries, including Lake Pontchartrain, could directly inform state and municipal health agencies on human exposure risks to upcoming cyanobacteria toxicity events by predicting cyanobacteria species shifts, potency, and toxin modality along the freshwater-to-marine continuum while also informing a longer-term projection on how the changing climate will impact the frequency and potency of such blooms.

Perception of con- and heterospecific injury cues in tadpoles of dendrobatid, ranid and bufonid frogs (Anura)

Predator-prey interactions are vital for organismal survival. They shape anti-predator mechanisms and often depend on sensory abilities. Tadpoles use chemical cues, such as injury cues (alarm cues), to assess predation risks and modify their life-history, morphology, and behaviours accordingly. However, the prevalence of chemically mediated anti-predator responses in species with distinct ecological niches (e.g. within phytotelmata) remains unknown, hindering our understanding of the ecological significance and evolution of alarm substances. Therefore, our study aimed to investigate chemically mediated anti-predator responses in tadpoles of two Neotropical poison dart frogs, Ranitomeya sirensis and Epipedobates anthonyi (and compare their responses to two Palearctic model organisms, Rana temporaria and Bufo bufo, which are known to utilise alarm substances). Through behavioural bioassays, we exposed predator-naïve tadpoles to extracts of each species (i.e. con- and heterospecific cues), including water as a control (i.e. five treatments per species). We assessed changes in their activity before and after stimulus introduction. Our results show that E. anthonyi did not respond to any of the stimuli, whereas R. sirensis displayed increased activity levels exclusively in response to conspecific cues, but not to heterospecific cues. With this, our findings suggest a specialized recognition system in R. sirensis, potentially directed at conspecific competitors but likely unrelated to anti-predator mechanisms. In contrast, E. anthonyi may be insensitive to injury cues or utilize alternative sensory modalities to respond to acute predation events. This study sheds light on the chemical alarm response system of Neotropical poison dart frog tadpoles, providing foundational understanding of how dendrobatids react to injury cues. It prompts questions about the ecological significance and evolutionary implications of chemical communication in species facing extreme resource limitation during development and underscores the importance of comparative research for understanding chemical communication in diverse aquatic ecosystems.

THE ROLE OF SNAKE VENOM IN THE BIOTIC INTERACTION

It is highlighted the ecological significance of biotic interactions. Biotic relationships can be intra- or interspecific, positive or negative and cover a wide range of interactions, including predation, commensalism, mutualism, competition and parasitism. It is indicated that snake venoms, which are the best studied, attract the greatest attention of researchers. The role of predators in the formation of the structure and functioning of ecosystems is analyzed. It has been established that the predator–prey ecological interaction causes mutual physiological, morphological and behavioral adaptations at the individual, intra- and inter-species levels. It is noted that toxins are important adaptation that arose due to evolution. Representatives of venomous animals are present in every ecosystem, more than 250,000 species of animals use their venom for predation, as well as for defense and survival. Іnformation about the types of poisonous and venomous animals is summarized in the article. The composition of animal venoms and the pathological consequences of their influence are presented. It is noted that the lost of habitats, climate change and biological invasions pose a threat to ecological processes that are associated with the interaction between species. The importance of snakes for ecosystems, their significance for trophic network and regulating pests is highlighted. It was found that from an ecological point of view, snake venom is an important functional trait that mediates biotic interaction between several organisms. Аt the same time it is a stressful biotic factor for other living beings

Trinitroaromatic explosives: Modern application, toxicological characterization, and methods of determination

Explosives such as tetryl and picric acid, which were common in the past, now have lost their combat relevance. However, they are often used for peaceful purposes individually and in combination with other trinitroaromatic compounds (e.g., trinitrotoluene). As a result of their use, environmental pollution occurs, followed by intoxication of plants, animals, and people. Cases of explosive poisoning during their production are also described.
 The symptoms of poisoning include both of general disorders and specific phenomena such as skin staining, impaired physiological efficiency of NADPh-dependent enzymes, genotoxicity, and immunotoxicity.
 Previous scientific studies established a trend toward the development of chemical-analytical probes. Various options for the sensor surface of the device and methods for detecting compounds are considered. To determine the explosives, ion mobility spectrometry is widely used, which is very rare for the chemicaltoxicological analysis of other groups of compounds.
 Simultaneously, methods commonly used in the analysis of narcotic and psychotropic substances (gas chromatography/ combination of high-performance liquid chromatography and mass spectrometry methods) are also applicable to determine trinitroaromatic explosives. However, the presence of nitro groups in their structure complicates such an analysis. This problem can be resolved by injecting cold samples directly to the column.
 Despite the availability of various developed techniques and methods, the possibility of their application to study biological matrices remains insufficient.
 Therefore, further studies of the chemicaltoxicological nature should be conducted to establish the optimal conditions for extracting the substances in question, the parameters of instrumental analysis, and the possibility of storing samples and for solving other problems of forensic medical examination.

Alkaloid-based chemical defenses and diet in six species of Australian poison frogs in the genus Pseudophryne (Myobatrachidae)

Alkaloid-based chemical defenses and diet in six species of Australian poison frogs in the genus Pseudophryne (Myobatrachidae)