Missed chances? Sequestration and non-sequestration of alkaloids by moths (Lepidoptera)

Some butterflies and moths sequester and retain noxious phytochemicals for defence against predators. In the present study, three moth species, the garden tiger moth, Arctia caja, the death hawk moth, Acherontia atropos, and the oleander hawk moth, Daphnis nerii, were tested whether they sequester alkaloids from their host plants. Whereas A. caja consistently sequestered atropine from Atropa belladonna, also when atropine sulfate was added to the alkaloid-free diet of the larvae, A. atropos and D. nerii were found to be unable to sequester alkaloids, neither atropine nor eburnamenine from Vinca major, respectively. Instead of acquiring toxicity as chemical defence, nocturnal lifestyle and cryptic attitudes may improve their chances of survival.

Proteomic analysis of the mandibular glands from the Chinese crocodile lizard, Shinisaurus crocodilurus - Another venomous lizard?

Based on its phylogenetic relationship to monitor lizards (Varanidae), Gila monsters (Heloderma spp.), and the earless monitor Lanthanotus borneesis, the Chinese crocodile lizard, Shinisaurus crocodilurus, has been assigned to the Toxicofera clade, which comprises venomous reptiles. However, no data about composition and biological activities of its oral secretion have been reported. In the present study, a proteomic analysis of the mandibular gland of S. crocodilurus and, for comparison, of the herbivorous Solomon Island skink Corucia zebrata, was performed. Scanning electron microscopy (SEM) of the teeth from S. crocodilurus revealed a sharp ridge on the anterior surface, but no grooves, whereas those of C. zebrata possess a flattened crown with a pointed cusp. Proteomic analysis of their gland extracts provided no evidence of venom-derived peptides or proteins, strongly supporting the non-venomous character of these lizards. Data are available via ProteomeXchange with identifier PXD039424.

Unraveling the venom chemistry with evidence for histamine as key regulator in the envenomation by caterpillar Automeris zaruma

Over the past decades, envenomation by caterpillars of Automeris spp. became an increasing health problem in Latin America. Accidental contact with the stinging spines of these caterpillars cause acute local pain, itching, inflammation and skin rashes that persists for days. Even when the cause is obvious, the exact molecular mechanisms responsible for the observed symptoms are yet to be elucidated. Here, we describe for the first time, an active compound in the venom and the study of the bioactivity of the venom extracted from the spines of the caterpillar Automeris zaruma. Electrophysiological screening of a library of membrane proteins important for pain and itch enabled us to investigate and reveal the mode of action of the venom of A. zaruma. Further mass spectrometric analysis (Q-TOF-MS) made it possible to establish a link between the bioactivity and the components found in the venom. We show that the spine extract of A. zaruma contains histamine that potently activates the four types of the human histamine receptors (H1R, H2R, H3R and H4R) with a selectivity preference towards H3R and H4R. Furthermore, a modulation of the target MRGPRX2 was found. Together, these findings are the first to explain the symptomology of A. zaruma envenomation, enabling us a better understanding of caterpillar envenomation and predict that the hurdle of the scarce efficacy of the currently used antihistaminic drugs can be overcome by including H3R and H4R blockers in the clinical used medication. Such an approach might be used for other caterpillar envenomation in the world and represent a significant improvement for the well-being of the patient.

A study on the genetic population structure and the tetrodotoxin content of rough-skinned newts, Taricha granulosa (Salamandridae), from their northern range of distribution

Rough-skinned newts, Taricha granulosa, which contain tetrodotoxin (TTX), a potent neurotoxin, are widely distributed along the west-coast of North America up to British Columbia (BC), Canada, and Southeast Alaska. Their genetic population structure using DNA-microsatellites and the TTX-content of specimens from British Columbia (Prince Rupert area) and Alaska (Revillagigedo Island, Shelter Island, and Juneau) were analysed. TTX-concentrations were low in newts from BC and Revillagigedo Island, but high in specimens from mainland Juneau, which had been deliberately introduced from Shelter Island, where TTX was not detectable in the individuals sampled. No significant genetic differences were detected between these populations, which may correlate with the high intraspecies variability of TTX. It is still an open question, which factors favour or induce the toxin production in the newts.

Thriving in a hostile world: Insights from the dietary strategy of two allopatric, closely related tepui summit endemic amphibians

To date, there has been no published investigation on the trophic diversity in any tepui summit vertebrate. In this paper, we analyzed the dietary composition of a tepui summit endemic toad, Oreophrynella quelchii from Roraima-tepui, and compared it with that of O. nigra from Kukenán-tepui, to examine to what extent diet differs between these two sister species across isolated, although neighboring, tepui tops. The digestive tracts of a total of 197 toads were dissected: 111 from O. quelchii and 86 from O. nigra. The diet composition of O. quelchii was relatively diverse, with 13 major prey categories; mites (Acari, 36.5%) and beetles (Coleoptera, 21.0%) numerically dominated its diet. Despite occurring on two different tepui summits, O. quelchii and O. nigra exhibited a similar diet composition, although in O. nigra mites (Acari, 42.4%) and hymenopterans (especially ants, 16.9%) numerically dominated the diet. The present data suggest that tepui summit Oreophrynella species are flexible in their diet and are active foragers that also feed on aquatic arthropods, successful strategies in tepui competitive environments.

Acquiring toxicity of a newt, Cynops orientalis

Tetrodotoxin (TTX) contents of wild-caught Chinese red-bellied newts, Cynops orientalis, and their offspring captive-reared from eggs to metamorphosed juveniles, were analysed using post-column LC-fluorescent detection (LC-FLD) and high resolution hydrophilic interaction liquid chromatography/mass spectrometry (HR-HILIC-LC/MS). TTX was detected in the parent newts and their eggs, but not in the larvae and juveniles raised under artificial condition over 20 months. However, juveniles reared in the presence of their parents, contained TTX-concentrations up to 8.05 μg/g. The origin of TTX may be implied from a close connection between the parents and their offspring.

[Anthrenus dermatitis : Case report with suggestions regarding causes and consequences]

Beetles of the genus Anthrenus are widespread worldwide and are quite common as grain and stock pests, especially in rural regions and suburban areas. The larvae of the beetles can trigger skin and occasionally mucosal reactions upon contact. The unfamiliar but typical image of "Anthrenus dermatitis" can easily be misinterpreted if beetle larvae are not detected or a causal link with them is not suspected. In the present article, the causes of Anthrenus dermatitis are discussed using as an example the larva of the woolly flower beetle (Anthrenus verbasci). For the examination of allergic causes, a prick-to-prick test with native larval material was performed in a patient and the specific IgE was determined by CAP coupling as well as in addition to a commercially available ImmunoCAP against larvae of a related beetle species. With the help of an immunoblot, an attempt was made to determine the responsible allergens in the native larval tissue. Important anatomical fine structures of the larva of a woolly herb flower beetle were analyzed using scanning electron microscopy to understand functional processes that lead to the clinical picture of Anthrenus dermatitis. Our allergological findings suggest an IgE-mediated, immediate-type allergy.

The earless monitor lizard Lanthanotus borneensis - A venomous animal?

Based on its mandibular gland secretion, the earless monitor lizard, Lanthanotus borneensis, has been considered a venomous animal like other members of the Toxicofera group, including Heloderma. In the present study, the gland structure and teeth of L. borneensis were examined by micro-tomography (μCT) and scanning electron microscopy (SEM), respectively, and proteomic analysis of the gland extract was performed. The mandibular gland consists of six compartments with separate ducts. The pleurodont teeth of the lower and upper jaw are not grooved but possess a sharp ridge on the anterior surface. Proteomic analysis of the gland extract confirmed previous studies that kallikrein enzymes are the major biologically active components. In view of the lizard's biology, its mandibular gland secretion is obviously not needed for prey capture or defence. It seems not justified the labelling of L. borneensis as a venomous animal. However, definitively answering this question requires toxinological studies on natural prey.

Revisited - Failure of tetrodotoxin to protect red-spotted newts, Notophthalmus viridescens, from endoparasites

Red-spotted newts, Notophthalmus viridescens, contain tetrodotoxin (TTX) and its analogue 6-epiTTX in variable concentrations. In a follow-up study, newts were sampled from a pond in Pennsylvania, USA, in 2010, 2014, and 2018. Their toxin levels were assayed by liquid-chromatography-fluorescence detection (LC-FLD), and assessment of their infection with endoparasites such as nematodes and helminths was performed by histological examination of internal organs. In the 2010 and 2014 samples, average prevalence of parasite infection was 53 and 60%, respectively, but reached 100% in the 2018 sample, where metacercaria stages of the digenean trematode genus Australapatemon/Apatemon (family: Strigeidae) were predominant causing severe tissue damage in liver and kidney. Mean values of TTX and 6-epiTTX were not significantly different in parasitized or parasite-free newts over the study period, confirming previous findings that host toxicity and parasite load are not negatively correlated. Whereas the role of TTX in defence against predators is undisputed, its efficacy to prevent parasitic infections is less obvious. Toxin-resistance of various metazoan parasites may promote their widespread occurrence in poisonous newts.

The voice from the hereafter: vocalisations in three species of Atelopus from the Venezuelan Andes, likely to be extinct

Atelopus is a species-rich group of Neotropical bufonids. Present knowledge on bioacoustics in this genus is relatively poor, as vocalisations have been described in only about one fifth of the ca. 100 species known. All studied members of the genus produce vocalisations although, with a few exceptions, most species lack a middle ear. Nonetheless, hearing has been demonstrated even in earless Atelopus making bioacoustics in these toads an inspiring research field. So far, three structural call types have been identified in the genus. As sympatry is uncommon in Atelopus, calls of the same type often vary little between species. Based on recordings from the 1980s, we describe vocalisations of three Venezuelan species (A. carbonerensis, A. mucubajiensis, A. tamaense) from the Cordillera de Mérida, commonly known as the Andes of Venezuela and the Tamá Massif, a Venezuelan spur of the Colombian Cordillera Oriental. Vocalisations correspond, in part, to the previously identified call types in Atelopus. Evaluation of the vocalisations of the three species presented in this study leads us to recognise a fourth structural call type for the genus. With this new addition, the Atelopus acoustic repertoire now includes (1) pulsed calls, (2) pure tone calls, (3) pulsed short calls and (4) pure tone short calls. The call descriptions provided here are valuable contributions to the bioacoustics of these Venezuelan Atelopus species, since all of them have experienced dramatic population declines that limit possibilities of further studies.

Petrifilm™ Rapid S. aureus Count Plate Method for Rapid Enumeration of Staphylococcus aureus in Selected Foods: Collaborative Study

A rehydratable dry-film plating method for Staphylococcus aureusin foods, the 3M™ Petrifilm™ Rapid S. aureus Count Plate method, was compared with AOAC® Official MethodSM 975.55 (Staphylococcus aureus in Foods). Nine foods—instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard—were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

Chemical Synthesis, Proper Folding, Nav Channel Selectivity Profile and Analgesic Properties of the Spider Peptide Phlotoxin 1

Phlotoxin-1 (PhlTx1) is a peptide previously identified in tarantula venom (Phlogius species) that belongs to the inhibitory cysteine-knot (ICK) toxin family. Like many ICK-based spider toxins, the synthesis of PhlTx1 appears particularly challenging, mostly for obtaining appropriate folding and concomitant suitable disulfide bridge formation. Herein, we describe a procedure for the chemical synthesis and the directed sequential disulfide bridge formation of PhlTx1 that allows for a straightforward production of this challenging peptide. We also performed extensive functional testing of PhlTx1 on 31 ion channel types and identified the voltage-gated sodium (Na_v) channel Na_v1.7 as the main target of this toxin. Moreover, we compared PhlTx1 activity to 10 other spider toxin activities on an automated patch-clamp system with Chinese Hamster Ovary (CHO) cells expressing human Na_v1.7. Performing these analyses in reproducible conditions allowed for classification according to the potency of the best natural Na_v1.7 peptide blockers. Finally, subsequent in vivo testing revealed that intrathecal injection of PhlTx1 reduces the response of mice to formalin in both the acute pain and inflammation phase without signs of neurotoxicity. PhlTx1 is thus an interesting toxin to investigate Na_v1.7 involvement in cellular excitability and pain.

Coping with noxious effects of quinine by praying mantids (Mantodea) and spiders (Araneae)

Because of its bitter taste, quinine elicits strong antifeedant and toxic effects in animals including arthropods. In the present study, two mantis, Sphodromantis viridis, Hierodula membranacea, and two spider species, Nephila edulis, Selenocosmia javanensis, were offered a quinine solution or prey (crickets) contaminated or injected with quinine, which they ingested and survived without apparent toxic symptoms. Analysis of their faeces and, in the case of spiders, of silk from their web revealed that quinine was excreted over a period of 8-12 (mantids) or 7 days (spiders). Interestingly, the silk glands of the spiders served as an additional excretory organ of quinine. Both, mantids and spiders were shown to tolerate high amounts of quinine in their prey. Obviously, the bitter taste of this compound is not perceived by their gustatory receptors and consequently triggers no aversive reactions.

Poor sequestration of toxic host plant cardenolides and their rapid loss in the milkweed butterfly Danaus chrysippus (Lepidoptera: Nymphalidae: Danainae: Danaini)

Butterflies of the genus Danaus are known to sequester toxic cardenolides from milkweed host plants (Apocynaceae). In particular, Danaus plexippus efficiently sequesters and stores these compounds, whereas D. chrysippus, is considered to poorly sequester cardenolides. To estimate its sequestration capability compared with that of D. plexippus, larvae of both species were jointly reared on Asclepias curassavica and the major cardenolides of the host plant, calotropin and calactin, were analyzed in adults sampled at different time intervals after eclosion. Both cardenolides were detected in body and wings of D. plexippus. Whereas the calotropin-concentration remained constant over a period of 24 days, that of calactin steadily decreased. In the body, but not in the wings of D. chrysippus, calactin only was detected in low amounts, which was then almost completely lost during the following 8 days after eclosion, suggesting that in contrast to D. plexippus, cardenolides seem to be less important for that butterfly's defence against predators.

[Jellyfish sting injuries]

BACKGROUND

Jellyfish are distributed worldwide; they cause local skin injuries upon contact which are often followed by systemic signs of envenoming.

OBJECTIVES

Which jellyfish species are of medical importance, which skin reactions and systemic symptoms occur, which first-aid measures and treatment options exist?

METHODS

Review of the medical literature and discussion of first-aid and therapeutic options.

RESULTS

Jellyfish capable of causing skin injuries occur in almost all oceans. Several jellyfish species may cause severe, potentially lethal, systemic symptoms; they include the Portuguese man-of-war (Physalia physalis) and box jellyfish (Chironex fleckeri, Carukia barnesi, Chiropsalmus quadrigatus).

CONCLUSIONS

Among the injuries and envenoming symptoms caused by marine organisms, jellyfish dermatitis should not be underestimated. Skin reactions may not only a dermatological problem, but also be accompanied by complex systemic toxic symptoms which are a challenge for internists.

Death of a South American fur seal (Arctocephalus australis) after the ingestion of toads--evaluation of toad poisoning by toxicological analysis

Animals in zoological gardens are at risk of severe and even lethal poisoning when they accidentally ingest toads. Here we report the case of an eleven month old male South American fur seal (Arctocephalus australis) which was found dead in its outdoor enclosure in the zoo of Dortmund, Germany. Autopsy revealed the presence of two adult, partly digested common toads (Bufo bufo) in the stomach. Toxicological analysis of the stomach content using high performance liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF MS) proved the presence of bufadienolides, the major cardiotoxic components of toad poisons. Using electrochemical luminescens immunoassay (ECLIA) compounds equivalent to digitoxin were detected in the blood sample confirming the absorption of toad poison components from the intestines into the circulation potentially leading to cardiac failure. In zoological gardens special precautions are necessary to protect non-native animals from encountering toads and the risk of poisoning, particularly in early spring, the spawning period of the toads.

Poor alkaloid sequestration by arrow poison frogs of the genus Phyllobates from Costa Rica

Frogs of the genus Phyllobates from Colombia are known to contain the highly toxic alkaloid batrachotoxin, but species from Central America exhibit only very low levels or are entirely free of this toxin. In the present study alcohol extracts from 101 specimens of Phyllobates lugubris and Phyllobates vittatus and 21 of three sympatric species (Dendrobates pumilio, Dendrobates auratus, Dendrobates granuliferus) from Costa Rica were analyzed by gas chromatography-mass spectrometry. Whereas the extracts of the Dendrobates species exhibited typical profiles of toxic alkaloids, those of the two Phyllobates species contained low levels of few alkaloids only, batrachotoxin was not detected. Although the feeding pattern of the Dendrobates and Phyllobates species are similar as revealed by examination of their stomach content (mainly ants and mites), the Phyllobates species are poorly sequestering alkaloids from their food source in contrast to the Dendrobates frogs.

Chemical camouflage--a frog's strategy to co-exist with aggressive ants

Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus). The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.

Venomous secretions from marine snails of the Terebridae family target acetylcholine receptors

Venoms from cone snails (Conidae) have been extensively studied during the last decades, but those from other members of the suborder Toxoglossa, such as of Terebridae and Turridae superfamilies attracted less interest so far. Here, we report the effects of venom and gland extracts from three species of the superfamily Terebridae. By 2-electrode voltage-clamp technique the gland extracts were tested on Xenopus oocytes expressing nicotinic acetylcholine receptors (nAChRs) of rat neuronal (α3β2, α3β4, α4β2, α4β4, α7) and muscle subtypes (α1β1γδ), and expressing potassium (Kv1.2 and Kv1.3) and sodium channels (Nav1.2, 1.3, 1.4, 1.6). The extracts were shown to exhibit remarkably high inhibitory activities on almost all nAChRs tested, in particular on the α7 subtype suggesting the presence of peptides of the A-superfamily from the venom of Conus species. In contrast, no effects on the potassium and sodium channels tested were observed. The venoms of terebrid snails may offer an additional source of novel biologically active peptides.

The mitochondrial genome of the venomous cone snail Conus consors

Cone snails are venomous predatory marine neogastropods that belong to the species-rich superfamily of the Conoidea. So far, the mitochondrial genomes of two cone snail species (Conus textile and Conus borgesi) have been described, and these feed on snails and worms, respectively. Here, we report the mitochondrial genome sequence of the fish-hunting cone snail Conus consors and describe a novel putative control region (CR) which seems to be absent in the mitochondrial DNA (mtDNA) of other cone snail species. This possible CR spans about 700 base pairs (bp) and is located between the genes encoding the transfer RNA for phenylalanine (tRNA-Phe, trnF) and cytochrome c oxidase subunit III (cox3). The novel putative CR contains several sequence motifs that suggest a role in mitochondrial replication and transcription.

Tetrodotoxin does not protect red-spotted newts, Notophthalmus viridescens, from intestinal parasites

Tetrodotoxin (TTX) and its analogue 6-epiTTX had been detected in the red-spotted newt, Notophthalmus viridescens. Thirty specimens of a population from Pennsylvania, USA were histologically examined for the presence of intestinal parasites. More than 50% were found to be infected with nematodes (Trichocephalidae), trematodes or cestodes (Pseudophyllidae). The mean values of TTX and 6-epiTTX in parasitized and in non-parasitized newts were not significantly different. Using a monoclonal antibody-based immunoenzymatic technique, TTX was localized in the intestinal tissue as well as in the parasites indicating that they accumulate the toxin and suggesting that TTX and 6-epiTTX are not providing protection from parasites to the newts.

Variability of tetrodotoxin and of its analogues in the red-spotted newt, Notophthalmus viridescens (Amphibia: Urodela: Salamandridae)

Efts and adult specimens (n = 142) of the red-spotted newt Notophthalmus viridescens from various locations in Canada and USA were analyzed for the presence of tetrodotoxin (TTX) and of its analogues 6-epitetrodotoxin and 11-oxotetrodotoxin. Considerable individual variations in toxin levels were found within and among populations from New Hampshire, New York, Pennsylvania, and Virginia ranging from non-detectable to 69 μg TTX per g newt. TTX and its analogues were absent in efts and adults from various locations in the Canadian province Nova Scotia, the northernmost distribution of the newt, and in adults from Florida. Newts kept in captivity for several years and reared on toxin-free diet lost their toxicity. Bayesian and maximum likelihood phylogenetic analysis of specimens from the various populations using three phylogenetic markers (COI, ND2 and 16S RNA) revealed that populations from the northern states of the USA and Canada are genetically homogenous, whereas the newts from Florida exhibited a much higher level of genetic divergence. An exogenous source of TTX in the newts either via the food chain or by synthesis of symbiotic bacteria is suggested to explain the high variability and lack of TTX in certain populations.

The Evolution of αD-Conopeptides Targeting Neuronal Nicotinic Acetylcholine Receptors

Venoms of the marine cone snails (Conus spp.) consist of numerous proteins and peptides showing a wide variety of biological activities such as on ion-channels and receptors. Peptides acting on neuronal nicotinic acetylcholine receptors belong to several peptide superfamilies including the recently described αD-conopeptides which are homodimers of identical peptides with 47-49 amino acids. Among the venom glands of 27 Conus species analyzed by cDNA cloning, precursors of αD-conopeptides were identified in four species only: C. betulinus, C. capitaneus, C. mustelinus, and C. vexillum. Phylogenetic analysis of the relationships among the αD-conopeptides revealed that they belong to clades, which are characterized by an AVV- and EMM-motif in the signal peptide sequence.

Biological activities of aqueous and organic extracts from tropical marine sponges

We report on screening tests of 66 extracts obtained from 35 marine sponge species from the Caribbean Sea (Curaçao) and from eight species from the Great Barrier Reef (Lizard Island). Extracts were prepared in aqueous and organic solvents and were tested for hemolytic, hemagglutinating, antibacterial and anti-acetylcholinesterase (AChE) activities, as well as their ability to inhibit or activate cell protein phosphatase 1 (PP1). The most interesting activities were obtained from extracts of Ircinia felix, Pandaros acanthifolium, Topsentia ophiraphidites, Verongula rigida and Neofibularia nolitangere. Aqueous and organic extracts of I. felix and V. rigida showed strong antibacterial activity. Topsentia aqueous and some organic extracts were strongly hemolytic, as were all organic extracts from I. felix. The strongest hemolytic activity was observed in aqueous extracts from P. acanthifolium. Organic extracts of N. nolitangere and I. felix inhibited PP1. The aqueous extract from Myrmekioderma styx possessed the strongest hemagglutinating activity, whilst AChE inhibiting activity was found only in a few sponges and was generally weak, except in the methanolic extract of T. ophiraphidites.

Foraging behaviour and territoriality of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of ants

Abstract

The present study investigates foraging and territorial behaviour of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of formicine and myrmicine ants, which constitute the main food source of the frogs. Species of the formicine ant genera Brachymyrmex and Paratrechina contain highly toxic alkaloids (pumiliotoxins), which the frogs incorporate and accumulate in their skin what may serve for predator deterrence. Twelve male frogs of two populations (primary and secondary forest) in Hitoy Cerere, Costa Rica, were observed each for a full day. Calling time, feeding attempts and time spent inside and outside the core area of their territories were recorded. Furthermore, twelve males of both populations were observed during the main foraging time to determine, whether the frogs search for prey in specific patches of their territories. The ants inside the core areas of twenty four frog territories were collected and classified to genus. Ants of the genera Brachymyrmex and Paratrechina were classified to species or morphospecies, respectively. The presence of formicine and myrmicine ants in territorial areas was compared to non-territorial sites. We found that formicine ants (Brachymyrmex and Paratrechina) were more present inside the territorial core areas than outside. The higher presence of these ants in the core areas was associated with longer foraging times. We verified that toxic alkaloids of the pumiliotoxin group are present in the dendrobatid frogs of Hitoy Cerere. The results of this study suggest that toxic diet may be linked to territoriality in this frog species.

Detection of hemolytic bacteria from Palythoa caribaeorum (Cnidaria, Zoantharia) using a novel palytoxin-screening assay

Palytoxin (PTX), one of the most potent and chemically complex marine toxins, is predominantly found in zoanthid corals and sporadically in dinoflagellates. Its biosynthesis and metabolic pathways are largely unknown. However, the widespread occurrence of the toxin in phylogenetically distinct marine organisms is consistent with its production by microorganisms and subsequent accumulation in the food chain. To investigate a possible microbial origin, bacteria from two zoanthid corals (Palythoa caribaeorum, Zoanthus pulchellus) and one sponge (Neofibularia nolitangere) were isolated. More than 250 bacteria were screened for hemolysis using a newly developed PTX-screening assay of which 7% showed PTX-like hemolytic activity. 16S rRNA gene sequencing revealed that these bacterial isolates belonged to strains of Bacillus cereus group (n = 11) as well as the genera Brevibacterium (n = 4) and Acinetobacter (n = 2). The results indicate the presence of Na+/K+-ATPase toxins and possibly PTX in hemolytic bacteria from P. caribaeorum.

New conopeptides of the D-superfamily selectively inhibiting neuronal nicotinic acetylcholine receptors

The venom of cone snails (Conus spp.) is a rich source of peptides exhibiting a wide variety of biological activities. Several of these conopeptides are neuronal nicotinic acetylcholine receptor (nAChR) antagonists and belong to the A-, M-, S-, C and the recently described D-superfamily (alphaD-conopeptides). Here we describe the discovery and characterization of two alphaD-conopeptides isolated from the venom of Conus mustelinus and Conus capitaneus. Their primary structure was determined by Edman degradation, MS/MS analysis and by a PCR based approach. These peptides show close structural homology to the alphaD-VxXIIA, -B and -C conopeptides from the venom of Conus vexillum and are dimers (about 11kDa) of similar or identical peptides with 49 amino acid residues and a characteristic arrangement of ten conserved cysteine residues. These novel types of conopeptides specifically block neuronal nAChRs of the alpha7, alpha3beta2 and alpha4beta2 subtypes in nanomolar concentrations. Due to their high affinity, these new ligands may provide a tool to decipher the localisation and function of the various neuronal nAChRs.

Chemical biology of the mutualistic relationships of sea anemones with fish and crustaceans

Fish species of the genera Amphiprion and Premnas (Perciformes: Pomacentridae) as well as various crustaceans seek protection from predators among the tentacles of sea anemones, where they live essentially unharmed from stinging by the host's nematocysts. The mucous coats of anemonefish and crustaceans have been suggested as mechanisms that prevent the discharge of the nematocysts upon contact. Whereas some fish species seem to produce their own protecting mucous coating, others may acquire mucus from the sea anemone during an acclimation period, as crustaceans do. Whether the natural or acquired mucus layers contain components that inhibit nematocyst discharge or simply lack compounds stimulating the stinging cell's exocytosis is still unknown.

Crystal structure of a novel myotoxic Arg49 phospholipase A2 homolog (zhaoermiatoxin) from Zhaoermia mangshanensis snake venom: insights into Arg49 coordination and the role of Lys122 in the polarization of the C-terminus

The venom of Zhaoermia mangshanensis, encountered solely in Mt Mang in China's Hunan Province, exhibits coagulant, phosphodiesterase, l-amino acid oxidase, kallikrein, phospholipase A2 and myotoxic activities. The catalytically inactive PLA2 homolog referred to as zhaoermiatoxin is highly myotoxic and displays high myonecrotic and edema activities. Zhaoermiatoxin possesses a molecular weight of 13,972Da, consists of 121 amino-acid residues cross-linked by seven disulfide bridges and shares high sequence homology with Lys49-PLA2s from the distantly related Asian pitvipers. However, zhaoermiatoxin possesses an arginine residue at position 49 instead of a lysine, thereby suggesting a secondary Lys49-->Arg substitution which results in a catalytically inactive protein. We have determined the first crystal structure of zhaoermiatoxin, an Arg49-PLA2, from Zhaoermia mangshanensis venom at 2.05 angstroms resolution, which represents a novel member of phospholipase A2 family. In this structure, unlike the Lys49 PLA2s, the C-terminus is well ordered and an unexpected non-polarized state of the putative calcium-binding loop due to the flip of Lys122 towards the bulk solvent is observed. The orientation of the Arg-49 side chain results in a similar binding mode to that observed in the Lys49 PLA2s; however, the guadinidium group is tri-coordinated by carbonyl oxygen atoms of the putative calcium-binding loop, whereas the Nzeta atom of lysine is tetra-coordinated as a result of the different conformation adopted by the putative calcium-binding loop.

Further studies on pumiliotoxin 251D and hydroquinone content of the skin secretion of Melanophryniscus species (Anura, Bufonidae) from Uruguay

In whole animal ethanolic extracts from adult specimens of Melanophryniscus atroluteus (27 specimens) and M. devincenzii (16 specimens) as well as of two egg clutches and four tadpole samples from the latter species, the major alkaloid pumiliotoxin (PTX) 251D and hydroquinone were assayed quantitatively by gas chromatography/mass spectrometry. All toad extracts contained high concentrations of PTX 251D and hydroquinone and exhibited considerable variation in the content of these compounds among individual specimens. The extracts of the eggs and tadpoles were entirely free of alkaloids as well as hydroquinone, pointing to a dietary origin of these compounds.

Crystallization and preliminary X-ray diffraction analysis of a novel Arg49 phospholipase A2 homologue from Zhaoermia mangshanensis venom

Zhaoermiatoxin, an Arg49 phospholipase A2 homologue from Zhaoermia mangshanensis (formerly Trimeresurus mangshanensis, Ermia mangshanensis) venom is a novel member of the PLA2-homologue family that possesses an arginine residue at position 49, probably arising from a secondary Lys49-->Arg substitution that does not alter the catalytic inactivity towards phospholipids. Like other Lys49 PLA2 homologues, zhaoermiatoxin induces oedema and strong myonecrosis without detectable PLA2 catalytic activity. A single crystal with maximum dimensions of 0.2 x 0.2 x 0.5 mm was used for X-ray diffraction data collection to a resolution of 2.05 A using synchrotron radiation and the diffraction pattern was indexed in the hexagonal space group P6(4), with unit-cell parameters a = 72.9, b = 72.9, c = 93.9 A.

Tetrodotoxin and its analogue 6-epitetrodotoxin in newts (Triturus spp.; Urodela, Salamandridae) from southern Germany

Tetrodotoxin (TTX) and its analogue 6-epitetrodotoxin (6-epiTTX) were quantitatively assayed in 59 newts representing four Triturus species (Triturus alpestris, Triturus cristatus, Triturus helveticus, Triturus vulgaris) from southern Germany by a post-column fluorescent-HPLC system. Both toxins were detected in only 15 specimens of the four species. The toxins levels varied considerably among individuals (TTX: 0.11-9.0microg/g; 6-epiTTX: 0.05-17.0microg/g). 6-epiTTX was found to be the major component.