Stonefish (Synanceia spp.) Ichthyocrinotoxins: An ecological review and prospectus for future research and biodiscovery.

Marine organisms possess a diverse array of unique substances, many with wide ranging potential for applications in medicine, industry, and other sectors. Stonefish (Synanceia spp.), a bottom-dwelling fish that inhabit shallow and intertidal waters throughout the Indo-Pacific, harbour two distinct substances, a venom, and an ichthyocrinotoxin. Stonefish are well-known for the potent venom associated with their dorsal spines as it poses a significant risk to public health. Consequently, much of the research on stonefish focusses on the venom, with the aim of improving outcomes in cases of envenomation. However, there has been a notable lack of research on stonefish ichthyocrinotoxins, a class of toxin that is synthesised within specialised epithelial cells (i.e., tubercles) and exuded onto the skin. This has resulted in a substantial knowledge gap in our understanding of these animals. This review aims to bridge this gap by consolidating literature on the ecological functions and biochemical attributes of ichthyocrinotoxins present in various fish species and juxtaposing it with the current state of knowledge of stonefish ecology. We highlight the roles of ichthyocrinotoxins in predator defence, bolstering innate immunity, and mitigating integumentary interactions with parasites and detrimental fouling organisms. The objective of this review is to identify promising research avenues that could shed light on the ecological functions of stonefish ichthyocrinotoxins and their potential practical applications as therapeutics and/or industrial products.

Inter-species variation in stonefish (Synanceia spp.) ichthyocrinotoxins; an ecological perspective.

Although stonefish (Synanceia spp.) are well-known to harbour a highly noxious defensive venom in their dorsal spines, very little is known about the composition and ecological function of the ichthyocrinotoxins that they secrete onto their epidermis. This study profiled reef (Synanceia verrucosa) and estuarine (Synanceia horrida) stonefish ichthyocrinotoxins via electrophoresis, liquid chromatography, and mass spectrometry to visualise and compare the composition of these toxins between the two species. Stonefish ichthyocrinotoxins were found to be multifarious concoctions that exhibited subtle differences between reef and estuarine species. We speculate that these variations and similarities are driven by the different and similar ecology of these fish species. Further research into the activity of the toxins components is now required to better understand their ecological role.

Anti-Glioma Effect of Pseudosynanceia melanostigma Venom on Isolated Mitochondria from Glioblastoma Cells

Background: Glioblastoma is the most common primary malignant tumor of the central nervous system that occurs in the spinal cord or brain. Pseudosynanceia melanostigma is a venomous stonefish in the Persian Gulf, which our knowledge about is little. This study's goal is to investigate the toxicity of stonefish crude venom on mitochondria isolated from U87 cells. Methods: In the first stage, we extracted venom stonefish and then isolated mitochondria have exposed to different concentrations of venom. Finally, mitochondrial toxicity parameters (Succinate dehydrogenase (SDH) activity, Reactive oxygen species (ROS), cytochrome c release, Mitochondrial Membrane Potential (MMP), and mitochondrial swelling) have evaluated. Results: To determine mitochondrial parameters, we used 115, 230, and 460 µg/ml concentrations. The results of our study show that the venom of stonefish selectively increases upstream parameters of apoptosis such as mitochondrial swelling, cytochrome c release, MMP collapse and ROS. Conclusion: This study suggests that Pseudosynanceia melanostigma crude venom has selectively caused toxicity by increasing active mitochondrial oxygen radicals. This venom could potentially be a candidate for the treatment of glioblastoma.

The Geographic Distribution, Venom Components, Pathology and Treatments of Stonefish (Synanceia spp.) Venom.

Stonefish are regarded as one of the most venomous fish in the world. Research on stonefish venom has chiefly focused on the in vitro and in vivo neurological, cardiovascular, cytotoxic and nociceptive effects of the venom. The last literature review on stonefish venom was published over a decade ago, and much has changed in the field since. In this review, we have generated a global map of the current distribution of all stonefish (Synanceia) species, presented a table of clinical case reports and provided up-to-date information about the development of polyspecific stonefish antivenom. We have also presented an overview of recent advancements in the biomolecular composition of stonefish venom, including the analysis of transcriptomic and proteomic data from Synanceia horrida venom gland. Moreover, this review highlights the need for further research on the composition and properties of stonefish venom, which may reveal novel molecules for drug discovery, development or other novel physiological uses.

Is stonefish Synanceia verrucosa envenomation potentially lethal?

Stonefish sting lethality in man has been scarcely documented since the middle of the 20th century. We report three clinical cases, including one fatality, emphasizing the cardiovascular toxicity of the Synanceia verrucosa venom, and its potentially lethal effects. All clinical data have been recently collected in New Caledonia and French Polynesia.

Ecological interactions between Gulf of Mexico snappers (Teleostei: Lutjanidae) and invasive red lionfish (Pterois volitans).

Indo-Pacific red lionfish (Pterois volitans) have invaded the western Atlantic, and most recently the northern Gulf of Mexico (nGOM), at a rapid pace. Given their generalist habitat affinities and diet, and strong ecological overlap with members of the commercially valuable snapper-grouper complex, increased density and abundance of lionfish could result in significant competitive interactions with nGOM commercially important species. We experimentally investigated the intensity of behavioral interactions between lionfish and indigenous, abundant and economically important juvenile nGOM red snapper (Lutjanus campechanus), and other increasingly abundant juvenile tropical snapper species (gray snapper-L. griseus and lane snapper-L. synagris) in large outdoor mesocosms to examine snapper vulnerabilities to lionfish competition. When paired with lionfish, red snapper swimming activity (i.e., time swimming and roving around experimental tank or at structure habitat during experiments) was significantly lower than in intraspecific control trials, but gray and lane snapper swimming activities in the presence of lionfish did not significantly differ from their intraspecific controls. Additionally in paired trials, red and lane snapper swimming activities were significantly lower than those of lionfish, while no significant difference in swimming activities was observed between lionfish and gray snapper. We found that red snapper prey consumption rates in the presence of lionfish were significantly lower than in their intraspecific 3-individual control trials, but when paired together no significant differences in prey consumption rates between red snapper and lionfish were observed. When paired with lane or gray snapper, lionfish were observed having comparatively higher prey consumption than snappers, or as observed in lionfish intraspecific 1-individual controls. However, lane and gray snapper consumption rates in the presence of lionfish did not significantly differ from those in intraspecific controls. These findings suggest that competition between juvenile snappers and invasive lionfish may be variable, with lionfish exhibiting differing degrees of competitive dominance and snappers exhibiting partial competitive vulnerability and resistance to lionfish. While the degree of intensity at which these interactions may occur in nGOM reefs may differ from those observed in our findings, this study enables greater understanding of the potential ecological effects of red lionfish on native reef fishes.

Environmental and Ecological Effects of Climate Change on Venomous Marine and Amphibious Species in the Wilderness.

INTRODUCTION: Recent analyses of data show a warming trend in global average air and sea surface ocean temperatures. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, the sea level has risen, and the concentrations of greenhouse gases have increased. This article will focus on climate change and projected effects on venomous marine and amphibious creatures with the potential impact on human health. METHODS: Retrospective analysis of environmental, ecological, and medical literature with a focus on climate change, toxinology, and future modeling specific to venomous aquatic and amphibious creatures. Species included venomous jellyfish, poisonous fish, crown-of-thorns starfish, sea snakes, and toxic frogs. RESULTS: In several projected scenarios, rising temperatures, weather extremes, and shifts in seasons will increase poisonous population numbers, particularly with certain marine creatures like jellyfish and crown-of-thorns starfish. Habitat expansions by lionfish and sea snakes are projected to occur. These phenomena, along with increases in human populations and coastal development will likely increase human-animal encounters. Other species, particularly amphibious toxic frogs, are declining rapidly due to their sensitivity to any temperature change or subtle alterations in the stability of their environment. If temperatures continue to rise to record levels over the next decades, it is predicted that the populations of these once plentiful and critically important animals to the aquatic ecosystem will decline and their geographic distributions will shrink. CONCLUSION: Review of the literature investigating the effect and forecasts of climate change on venomous marine and amphibious creatures has demonstrated that temperature extremes and changes to climatic norms will likely have a dramatic effect on these toxicological organisms. The effects of climate change on these species through temperature alteration and rising coastal waters will influence each species differently and in turn potentially affect commercial industries, travel, tourism, and human health.

Biochemical and histopathological effects of the stonefish (Synanceia verrucosa) venom in rats.

The Reef Stonefish (Synanceia verrucosa) is one of the most dangerous venomous fish known, and has caused occasional human fatalities. The present study was designed to examine some of the pathological effects of the venom from this fish in Sprague Dawley rats. Crude venom was extracted from venom glands of the dorsal spines of stonefish specimens collected from coral reefs in the Gulf of Aqaba (in the northeastern branch of the Red Sea). The rats were given intramuscular injections of the venom and acute toxicity and effect on selected serum marker enzymes as well as normal architecture of vital organs were evaluated. The rat 24 h LD50 was 38 µg/kg body weight. The serum biochemical markers; alanine transaminase (ALT), lactate dehydrogenase (LDH) and creatine kinase (CK) increased after 6 h of administration of a sub lethal dose of the venom and remained significantly raised at 24 h. Amylase levels also significantly increased after venom injection. The venom caused histological damage manifested as an interstitial hemorrhage, inflammatory cell infiltration, and necrosis. The demonstrated rises in the levels of different critical biochemical parameters in the serum may have led to the observed abnormal morphological changes in these organs. These results may account for some of the clinical manifestations observed in victims of stonefish envenomation. Thus, the presented data provide further in vivo evidence of the stonefish toxic effects that may threaten human life and call for the need for special measures to be considered.

Sequence analysis of the cDNA encoding for SpCTx: a lethal factor from scorpionfish venom ( Scorpaena plumieri )

Background: Lethal factors are multifunctional oligomeric proteins found in the venomous apparatus of Scorpaeniformes fish. These toxins elicit not only an array of biological responses in vitro but also cardiovascular disorders and strong hemolytic, nociceptive and edematogenic activities in vivo. This work describes the cloning and molecular identification of two toxin subunits, denominated Sp-CTx- and Sp-CTx-, from scorpionfish venom ( Scorpaena plumieri ). Methods: The primary structures were deduced after cDNA amplification by PCR with primers from conserved sequences described in Scorpaeniformes toxins. Following DNA sequencing and bioinformatic analysis, the tridimensional structures of both subunits were modeled. Results: The translated sequences (702 amino acids, each subunit) show homology with other lethal factors, while alignment between Sp-CTx- and Sp-CTx- shows 54% identity. The subunits lack N-terminal signal sequences and display masses of approximately 80 kDa each. Both Sp-CTx subunits display a B30.2/SPRY domain at the C-terminal region with typically conserved motifs as described in these toxins. Secondary structure prediction identified six -helices 18 residues long in both and subunits, some of them amphiphilic with their N-terminal flanked by many basic residues, creating a cationic site associated with the cytolytic activity of these toxins. Antimicrobial potential sites were identified in Sp-CTx and share some features with other peptides presenting variable and broad-spectrum activity...

Occurrence of a stonefish toxin-like toxin in the venom of the rabbitfish Siganus fuscescens.

Rabbitfish belonging to the order Perciformes are well-known venomous fish that are frequently involved in human accidents. However little research has been done into either the whole venom toxicities or the structures and properties of their venom toxins. In this study, we first examined biological activities of the crude venom extract prepared from dorsal spines of Siganus fuscescens, a rabbitfish most commonly found along the coasts of Japan. As a result, the crude venom extract was shown to have mouse-lethal activity, hemolytic activity against rabbit erythrocytes, edema-forming activity and nociceptive activity, similar to the known scorpaeniform fish toxins (stonefish toxins and their analogues). Then, the primary structure of the S. fuscescens toxin was successfully elucidated by the same cDNA cloning strategy as previously employed for the toxins of some scorpaeniform fish (lionfish, devil stinger and waspfish). The S. fuscescens toxin is obviously an analogue of stonefish toxins, being composed of two kinds of subunits, an α-subunit of 703 amino acid residues and a ß-subunit of 699 amino acid residues. Furthermore, the genes encoding both subunits were cloned from genomic DNA and shown to have an architecture of three exons and two introns, as reported for those of the scorpaeniform fish toxins. This study is the first to demonstrate the occurrence of stonefish toxin-like toxins in perciform fish.

Heat deactivation of the stonefish Synanceia horrida venom - implications for first-aid management.

OBJECTIVES: To investigate the effects of temperature and hot water immersion time on neutralising venom lethality of the Australian estuarine stonefish (Synanceia horrida). DESIGN: Depths of the spines were measured while venom was extracted from S. horrida individuals. The venom was then exposed to temperatures of 4°C, 37.0°C, 40.1°C, 42.3°C, 45.0°C, 47.7°C, 55.2°C, and 60.0°C for either five or 20 minutes incubation periods. Venom samples were added to cultured human cardiomyocytes and cell viability curves were produced using the ACEA's xCELLigence real-time cell monitoring system. MAIN OUTCOME MEASURES: Determination of venom lethality on cardiomyocytes at a range of temperatures. RESULTS: The average depth of the spine required to go into a victims' flesh before the venom gland compressed and expelled venom was 18 mm. Cardiomyocytes exposed to heat-treated venom for five minutes required higher temperatures to neutralise 99% of the venom, namely 44.6°C in comparison to 42.1°C with an incubation time of 20 minutes. CONCLUSION: This study supports the use of hot water immersion therapy in the treatment of S. horrida stings. It is suggested that due to the depth of the puncture wound longer incubation times should be sought to allow heat to penetrate the deeper portions of the dermis and effectively begin venom deactivation.

[Partial finger amputation after weever sting and second-degree burn].

The greater weever (Trachinus draco) is the only venomous fish in Denmark, and if stung by the weever the venom may cause symptoms such as pain, headache, nausea, dizziness and in severe cases systemic allergic reaction or tissue necrosis. The venom is heat-labile and should therefore be treated with warm water to the afflicted area. We report a case of a patient who was stung in the second finger and because of the treatment, he got a second-degree burn, that may have enhanced the effect of the venom, thus resulting in partial finger amputation.

The Cardiovascular and Neurotoxic Effects of the Venoms of Six Bony and Cartilaginous Fish Species.

Fish venoms are often poorly studied, in part due to the difficulty in obtaining, extracting, and storing them. In this study, we characterize the cardiovascular and neurotoxic effects of the venoms from the following six species of fish: the cartilaginous stingrays Neotrygon kuhlii and Himantura toshi, and the bony fish Platycephalus fucus, Girella tricuspidata, Mugil cephalus, and Dentex tumifrons. All venoms (10-100 µg/kg, i.v.), except G. tricuspidata and P. fuscus, induced a biphasic response on mean arterial pressure (MAP) in the anesthetised rat. P. fucus venom exhibited a hypotensive response, while venom from G. tricuspidata displayed a single depressor response. All venoms induced cardiovascular collapse at 200 µg/kg, i.v. The in vitro neurotoxic effects of venom were examined using the chick biventer cervicis nerve-muscle (CBCNM) preparation. N. kuhlii, H. toshi, and P. fucus venoms caused concentration-dependent inhibition of indirect twitches in the CBCNM preparation. These three venoms also inhibited responses to exogenous acetylcholine (ACh) and carbachol (CCh), but not potassium chloride (KCl), indicating a post-synaptic mode of action. Venom from G. tricuspidata, M. cephalus, and D. tumifrons had no significant effect on indirect twitches or agonist responses in the CBCNM. Our results demonstrate that envenoming by these species of fish may result in moderate cardiovascular and/or neurotoxic effects. Future studies aimed at identifying the molecules responsible for these effects could uncover potentially novel lead compounds for future pharmaceuticals, in addition to generating new knowledge about the evolutionary relationships between venomous animals.

Relationship between food and venom production in the estuarine stonefish Synanceia horrida.

BACKGROUND: The potential costs of venom production may be significant to many marine venomous taxa. In general, the parameters that influence the rate of venom production are poorly understood, but seem to be related to feeding frequency. METHODS: This study examines the effects of starvation on venom profile and venom yield on the estuarine stonefish (Synanceia horrida). In total, the venom of eight stonefishes was tested under two feeding regimes. Over a four week period, one of the two groups underwent an episode of suspended feeding, while the other was fed on a daily basis. The effect of time on venom replacement was determined by a paired T-test. ANOVA was performed to analyze differences in venom weight between fed and unfed treatments. RESULTS: Nutritional suspension was found to have a significant effect on the quantity of venom produced. SDS-PAGE gel and FPLC revealed that the components of the venom collected from both groups were similar, indicating that four weeks is an adequate time to regenerate key venom components but not replenish initial venom quantities. CONCLUSIONS: Venom production was found to be affected by starvation.

Marine Scorpaenidae Envenomation in Travelers: Epidemiology, Management, and Prevention.

BACKGROUND: The Scorpaenidae are a large family of venomous marine fish that include scorpionfish, lionfish, and stonefish. Although most stonefish are confined to the Indo-Pacific, scorpionfish are distributed in the tropics worldwide, and two species of Indo-Pacific lionfish were inadvertently introduced into the Eastern Atlantic in the 1990s. Since then, lionfish have invaded shallow reef systems in the Eastern Atlantic, Gulf of Mexico, and Caribbean Sea. All of these regions are popular travel destinations for beachcombing, fishing, swimming, and scuba diving-recreational activities that increase risks of Scorpaenidae envenomation. METHODS: To meet the objectives of describing species-specific presenting clinical manifestations, diagnostic and treatment strategies, and outcomes of Scorpaenidae envenomation in travelers, Internet search engines were queried with the key words. RESULTS: Well-conducted, retrospective epidemiological investigations of Scorpaenidae envenomation case series concluded: (1) most cases occurred in young adult male vacationers visiting endemic regions; (2) victims sought medical attention for pain control within 2 hours of injury and presented with intense pain, edema, and erythema in affected extremities; (3) systemic manifestations and surgical interventions were relatively uncommon following initial management with hot water soaks and parenteral analgesics; (4) all cases required tetanus prophylaxis; deeply penetrating, lacerated, and necrotic wounds required antibiotic prophylaxis; and (5) equine Fab stonefish antivenom does have antigen-neutralizing cross-reactivities with both Indo-Pacific and Atlantic Scorpaenidae species and is indicated in severe scorpionfish and stonefish envenomation worldwide. CONCLUSIONS: Travel medicine practitioners should counsel their patients about Scorpaenidae envenomation risks in endemic regions and maintain a high index of suspicion regarding Scorpaenidae envenomation in all travelers returning from tropical beach and ocean holidays and reporting painful fish sting injuries.