Animal venoms and toxins Research Papers (original) (raw)

Background: Vertebrate predators use a broad arsenal of behaviors and weaponry for overcoming fractious and potentially dangerous prey. A unique array of predatory strategies occur among snakes, ranging from mechanical modes of... more

Background: Vertebrate predators use a broad arsenal of behaviors and weaponry for overcoming fractious and potentially dangerous prey. A unique array of predatory strategies occur among snakes, ranging from mechanical modes of constriction and jaw-holding in non-venomous snakes, to a chemical means, venom, for quickly dispatching prey. However, even among venomous snakes, different prey handling strategies are utilized, varying from the strike-and-hold behaviors exhibited by highly toxic elapid snakes to the rapid strike-and-release envenomation seen in viperid snakes. For vipers, this mode of envenomation represents a minimal risk predatory strategy by permitting little contact with or retaliation from prey, but it adds the additional task of relocating envenomated prey which has wandered from the attack site. This task is further confounded by trails of other unstruck conspecific or heterospecific prey. Despite decades of behavioral study, researchers still do not know the molecular mechanism which allows for prey relocation. Results: During behavioral discrimination trials (vomeronasal responsiveness) to euthanized mice injected with sizefractionated venom, Crotalus atrox responded significantly to only one protein peak. Assays for enzymes common in rattlesnake venoms, such as exonuclease, L-amino acid oxidase, metalloproteinase, thrombin-like and kallikreinlike serine proteases and phospholipase A 2 , showed that vomeronasal responsiveness was not dependent on enzymatic activity. Using mass spectrometry and N-terminal sequencing, we identified the proteins responsible for envenomated prey discrimination as the non-enzymatic disintegrins crotatroxin 1 and 2. Our results demonstrate a novel and critical biological role for venom disintegrins far beyond their well-established role in disruption of cellcell and cell-extracellular matrix interactions. Conclusions: These findings reveal the evolutionary significance of free disintegrins in venoms as the molecular mechanism in vipers allowing for effective relocation of envenomated prey. The presence of free disintegrins in turn has led to evolution of a major behavioral adaptation (strike-and-release), characteristic of only rattlesnakes and other vipers, which exploits and refines the efficiency of a pre-existing chemical means of predation and a highly sensitive olfaction system. This system of a predator chemically tagging prey represents a novel trend in the coevolution of predator-prey relationships.

Venoms of several animals have been used to study various physiopathologic processes, and also to offer opportunity to design and develop new therapeutic drugs. We briefly review certain wasp venom components and their biological effects,... more

Venoms of several animals have been used to study various physiopathologic processes, and also to offer
opportunity to design and develop new therapeutic drugs. We briefly review certain wasp venom components and their
biological effects, which may be potential sources of novel pharmacologically active compounds

The evolutionary origin and diversification of the reptilian venom system is described. The resolution of higher-order molecular phylogenetics has clearly established that a venom system is ancestral to snakes. The diversification of the... more

The evolutionary origin and diversification of the reptilian venom system is described. The resolution of higher-order molecular phylogenetics has clearly established that a venom system is ancestral to snakes. The diversification of the venom system within lizards is discussed, as is the role of venom delivery in the behavioural ecology of these taxa (particularly Varanus komodoensis). The more extensive diversification of the venom system in snakes is summarised, including its loss in some clades.

As viper snake bites are the most important cause of snake-bite mortality in several places of the world, the present study spotlighted this type of snake bites among snakebites patients received at the Poison Control Center, Ain Shams... more

As viper snake bites are the most important cause of snake-bite mortality in several places of the world, the present study spotlighted this type of snake bites among snakebites patients received at the Poison Control Center, Ain Shams Faculty of Medicine (PCCA). The study aimed at scrutinizing the epidemiology, the presenting symptoms and signs, the therapeutic procedures employed and the outcome of these cases during the year 2006. It was found that out of 140 cases of snake bites received at the center, forty patients were bitten by a viper snake. Full history taking and clinical examination were done to every case. Blood samples were drawn from every case for biochemical analysis of the coagulation profile, blood picture, CPK, AST, ALT, serum creatinine, blood urea, serum sodium and potassium, blood glucose and C3 and C4. The study revealed that most of the patients were adult males (60%) and adult females were 20%. Children represented 20% of the cases and were equally distributed betweeen both sexes. Biting was accidental in 82.5% of cases and occupational in the remaining 17.5%. Forty five per cent of the bites took place in the street and 37.5 % happened at home. The lower limbs were the site of the bite in 78.5 % of cases. Most of the bites had occurred during summer months (April through August). Winter months (November through March) showed no cases at all. The Greater Cairo was the habitat of most cases. It was found that 90% of cases presented to the center within 30 min to 3 hours after being bitten. Only 10% presented with a delay of 4 hours or more. The presenting manifestations included fang marks and alterations of pulse rate , blood pressure, respiration and body temperature. Lymphadenopathy was evident in 75% of cases. Hematological manifestation included bleeding gums, heamaturia, petechial hemorrhages and ecchymosis. Neurogenic shock and panic were evident in 95 % of the patients. The coagulation profile of the 40 cases showed significant prolongation of PT and PTT, lowering of fibrinogen level and significant increase of Fibrin Degradation Products (FDP) before treatment. CPK was relatively elevated before treatment, however, liver enzymes and renal indices were normal. Complement 3 and 4 were also relatively decreased before treatment. All the cases received antivenom therapy after being diagnosed. Two to four vials were enough in 26 cases (68 %) and 5 vials or more were needed in 14 cases (32%). Fresh frozen plasma was neecessary in 6 cases (15%) and whole blood transfusion was required to 16 cases (40%). All relatively altered biochemical parameters were normalized after treatment. No deaths occurred among the patients and all of them were treated and discharged whether from the receiving outpatient ward (24 patients) or after being admitted to the ICU (16 patients). It was concluded that the management protocol employed was effective. Investigating cases of snakebites caused by other types of snakes is recommended and exchange of information about this problem with similar health facilities should be done.

Ants (Formicidae) represent a taxonomically diverse group of hymenopterans with over 13,000 extant species, the majority of which inject or spray secretions from a venom gland. The evolutionary success of ants is mostly due to their... more

Ants (Formicidae) represent a taxonomically diverse group of hymenopterans with over 13,000 extant species, the majority of which inject or spray secretions from a venom gland. The evolutionary success of ants is mostly due to their unique eusociality that has permitted them to develop complex collaborative strategies, partly involving their venom secretions, to defend their nest against predators, microbial pathogens, ant competitors, and to hunt prey. Activities of ant venom include paralytic, cytolytic, haemolytic, allergenic, pro-inflammatory, insecticidal, antimicrobial, and pain-producing pharmacologic activities, while non-toxic functions include roles in chemical communication involving trail and sex pheromones, deterrents, and aggregators. While these diverse activities in ant venoms have until now been largely understudied due to the small venom yield from ants, modern analytical and venomic techniques are beginning to reveal the diversity of toxin structure and function. As such, ant venoms are distinct from other venomous animals, not only rich in linear, dimeric and disulfide-bonded peptides and bioactive proteins, but also other volatile and non-volatile compounds such as alkaloids and hydrocarbons. The present review details the unique structures and pharmacologies of known ant venom proteinaceous and alkaloidal toxins and their potential as a source of novel bioinsecticides and therapeutic agents.

The literature on chemical weaponry of organisms is vast and provides a rich understanding of the composition and mechanisms of the toxins and other components involved. However, an ecological or evolutionary perspective has often been... more

The literature on chemical weaponry of organisms is vast and provides a rich understanding of the composition and mechanisms of the toxins and other components involved. However, an ecological or evolutionary perspective has often been lacking and is largely limited to (1) molecular evolutionary studies of particular toxins (lacking an ecological view); (2) comparisons across different species that ignore phylogenetic relatedness (lacking an evolutionary view); or (3) descriptive studies of venom composition and toxicology that contain post hoc and untested ecological or evolutionary interpretations (a common event but essentially uninformative speculation). Conveniently, comparative biologists have prolifically been developing and using a wide range of phylogenetic comparative methods that allow us to explicitly address many ecological and evolutionary questions relating to venoms and poisons. Nevertheless, these analytical tools and approaches are rarely used and poorly known by biological toxinologists and toxicologists. In this review I aim to (1) introduce phylogenetic comparative methods to the latter audience; (2) highlight the range of questions that can be addressed using them; and (3) encourage biological toxinologists and toxicologists to either seek out adequate training in comparative biology or seek collaboration with comparative biologists to reap the fruits of a powerful interdisciplinary approach to the field.

Cnidarian envenomations are the leading cause of severe and lethal human sting injuries from marine life. The total amount of venom discharged into sting-site tissues, sometimes referred to as " venom load " , has been previously shown to... more

Cnidarian envenomations are the leading cause of severe and lethal human sting injuries from marine life. The total amount of venom discharged into sting-site tissues, sometimes referred to as " venom load " , has been previously shown to correlate with tentacle contact length and sequelae severity. Since <1% of cnidae discharge upon initial tentacle contact, effective and safe removal of adherent tentacles is of paramount importance in the management of life-threatening cubozoan stings. We evaluated whether common rinse solutions or scraping increased venom load as measured in a direct functional assay of venom activity (hemolysis). Scraping significantly increased hemolysis by increasing cnidae discharge. For Alatina alata, increases did not occur if the tentacles were first doused with vinegar or if heat was applied. However, in Chironex fleckeri, vinegar dousing and heat treatment were less effective, and the best outcomes occurred with the use of venom-inhibiting technologies (Sting No More ® products). Seawater rinsing, considered a " no-harm " alternative, significantly increased venom load. The application of ice severely exacerbated A. alata stings, but had a less pronounced effect on C. fleckeri stings, while heat application markedly reduced hemolysis for both species. Our results do not support scraping or seawater rinsing to remove adherent tentacles.

The LD50 is an important metric for venom studies and antivenom development. It has been shown that several variables in the protocol influence the LD50 value obtained, such as venom source, extraction and treatment and administration... more

The LD50 is an important metric for venom studies and antivenom development. It has
been shown that several variables in the protocol influence the LD50 value obtained, such
as venom source, extraction and treatment and administration route. These inconsistencies
reduce the utility of the results of these test for comparative studies. In
scorpion venom LD50 assays, often only the soluble fraction of the venom is used, whereas
other studies use the whole venom. We here tested the toxicity of the soluble fraction in
isolation, and of the whole venom in two different systems: chick embryos and mealworms
Tenebrio molitor. Ten microliters of venom solutions from Hadrurus arizonensis,
Leiurus quinquestriatus, Androctonus australis, Grosphus grandidieri and Heterometrus laoticus
were applied to five day old chicken embryos at stage 25e27. Our results showed no
significant differences between the LD50 based on the whole venom versus that of only the
soluble fraction and in the chicken embryo assay in four of the five scorpion species tested.
H. laoticus however, showed a significantly lower LD50 value for the whole venom than the
soluble fraction. In assays on mealworms however, this pattern was not seen. Nonetheless,
caution may be warranted when using LD50 values obtained from only the soluble fraction.
The LD50 values of the five species in this study, based on the chicken embryo assay,
showed good correlation with values from the literature based on mouse studies. This
suggests that the chick embryo assay may be an economic alternative to rodent assays for
scorpion LD50 studies.

Cubozoa-class cnidarian (box jellyfi sh) envenomations constitute a complex medical challenge and public health threat. There are currently no validated standards of care for life-threatening stings. Increasing numbers and reported... more

Cubozoa-class cnidarian (box jellyfi sh) envenomations constitute a complex medical challenge and public health threat. There are currently no validated standards of care for life-threatening stings. Increasing numbers and reported geographic ranges of serious cubozoan envenomations underscore the urgent need for mechanism-based emergency therapeutic options for lifeguards, fi rst responders and clinicians. For the most part, treatment and management approaches have been symptom-driven, utilizing therapeutics familiar to the practitioner and often based on extrapolation from other envenomation sequelae, rather than cubozoan-specifi c standardized protocols. Newly elucidated mechanisms of pathogenesis provide a context for directed clinical research to test novel therapeutic approaches that could greatly diminish human suffering and improve outcomes. The current state of our understanding about the pathophysiology of cnidarian envenomation and emerging therapeutic options for the medically relevant cubozoans will be presented.

Australia is the stronghold of the front-fanged venomous snake family Elapidae. The Australasian elapid snake radiation, which includes approximately 100 terrestrial species in Australia, as well as Melanesian species and all the world's... more

Australia is the stronghold of the front-fanged venomous snake family Elapidae. The Australasian elapid snake radiation, which includes approximately 100 terrestrial species in Australia, as well as Melanesian species and all the world's true sea snakes, may be less than 12 million years old. The incredible phenotypic and ecological diversity of the clade is matched by considerable diversity in venom composition. The clade's evolutionary youth and dynamic evolution should make it of particular interest to toxinologists, however, the majority of species, which are small, typically inoffensive, and seldom encountered by non-herpetologists, have been almost completely neglected by researchers. The present study investigates the venom composition of 28 species proteomically, revealing several interesting trends in venom composition, and reports, for the first time in elapid snakes, the existence of an ontogenetic shift in the venom composition and activity of brown snakes (Pseudonaja sp.). Trends in venom composition are compared to the snakes' feeding ecology and the paper concludes with an extended discussion of the selection pressures shaping the evolution of snake venom.

Fire ants are well-known by their aggressive stinging behavior, causing many stinging incidents of medical importance. The limited availability of fire ant venom for scientific and clinical uses has restricted, up to now, the knowledge... more

Fire ants are well-known by their aggressive stinging behavior, causing many stinging incidents of medical importance. The limited availability of fire ant venom for scientific and clinical uses has restricted, up to now, the knowledge about the biochemistry, immunology, and pharmacology of these venoms. For this study, S. invicta venom was obtained commercially and used for proteomic characterization. For this purpose, the combination of gel-based and gel-free proteomic strategies was used to assign the proteomic profile of the venom from the fire ant S. invicta. This experimental approach permitted the identification of 46 proteins, which were organized into four different groups according to their potential role in fire ant venom: true venom components, housekeeping proteins, body muscle proteins, and proteins involved in chemical communication. The active venom components that may not present toxic roles were classified into three subgroups according to their potential functions: self-venom protection, colony asepsis, and chemical communication. Meanwhile, the proteins classified as true toxins, based on their functions after being injected into the victims' bodies by the fire ants, were classified in five other subgroups: proteins influencing the homeostasis of the victims, neurotoxins, proteins that promote venom diffusion, proteins that cause tissue damage/inflammation, and allergens.

Abstract: Cnidarians are the oldest extant lineage of venomous animals. Despite their simple anatomy, they are capable of subduing or repelling prey and predator species that are far more complex and recently evolved. Utilizing... more

Abstract: Cnidarians are the oldest extant lineage of venomous animals. Despite their
simple anatomy, they are capable of subduing or repelling prey and predator species that are
far more complex and recently evolved. Utilizing specialized penetrating nematocysts,
cnidarians inject the nematocyst content or “venom” that initiates toxic and immunological
reactions in the envenomated organism. These venoms contain enzymes, potent pore
forming toxins, and neurotoxins. Enzymes include lipolytic and proteolytic proteins that
catabolize prey tissues. Cnidarian pore forming toxins self-assemble to form robust
membrane pores that can cause cell death via osmotic lysis. Neurotoxins exhibit rapid ion
channel specific activities. In addition, certain cnidarian venoms contain or induce the
release of host vasodilatory biogenic amines such as serotonin, histamine, bunodosine and
caissarone accelerating the pathogenic effects of other venom enzymes and porins. The
cnidarian attacking/defending mechanism is fast and efficient, and massive envenomation
of humans may result in death, in some cases within a few minutes to an hour after sting.
The complexity of venom components represents a unique therapeutic challenge and probably
reflects the ancient evolutionary history of the cnidarian venom system. Thus, they are
invaluable as a therapeutic target for sting treatment or as lead compounds for drug design.

The episodic nature of natural selection and the accumulation of extreme sequence divergence in venom-encoding genes over long periods of evolutionary time can obscure the signature of positive Darwinian selection. Recognition of the true... more

The episodic nature of natural selection and the accumulation of extreme sequence divergence in venom-encoding genes over long periods of evolutionary time can obscure the signature of positive Darwinian selection. Recognition of the true biocomplexity is further hampered by the limited taxon selection, with easy to obtain or medically important species typically being the subject of intense venom research, relative to the actual taxonomical diversity in nature. This holds true for scorpions, which are one of the most ancient terrestrial venomous animal lineages. The family Buthidae that includes all the medically significant species has been intensely investigated around the

Toxins and venom components that target voltage-gated sodium (NaV) channels have evolved numerous times due to the importance of this class of ion channels in the normal physiological function of peripheral and central neurons as well as... more

Toxins and venom components that target voltage-gated sodium (NaV) channels have evolved numerous times due to the importance of this class of ion channels in the normal physiological function of peripheral and central neurons as well as cardiac and skeletal muscle. NaV channel activators in particular have been isolated from the venom of spiders, wasps, snakes, scorpions, cone snails and sea anemone and are also produced by plants, bacteria and algae. These compounds have provided key insight into the molecular structure, function and pathophysiological roles of NaV channels and are important tools due to their at times exquisite subtype-selectivity. We review the pharmacology of NaV channel activators with particular emphasis on mammalian isoforms and discuss putative applications for these compounds.

Ecuador harbors one of the most diverse Neotropical scorpion faunas, hereby updated to 47 species contained within eight genera and five families, which inhabits the “Costa” (n = 17), “Sierra” (n = 34), “Oriente” (n = 16) and “Insular” (n... more

Ecuador harbors one of the most diverse Neotropical scorpion faunas, hereby updated to 47 species contained within
eight genera and five families, which inhabits the “Costa” (n = 17), “Sierra” (n = 34), “Oriente” (n = 16) and “Insular” (n = 2)
biogeographical regions, corresponding to the western coastal, Andean, Amazonian, and the Galápagos archipelago
regions, respectively. The genus Tityus Koch, in the family Buthidae, responsible for severe/fatal accidents elsewhere in
northern South America and the Amazonia, is represented in Ecuador by 16 species, including T. asthenes, which has
caused fatalities in Colombia and Panama, and now in the Ecuadorian provinces of Morona Santiago and Sucumbíos.
Underestimation of the medical significance of scorpion envenoming in Ecuador arises from the fact that Centruroides
margaritatus (Gervais) (family Buthidae) and Teuthraustes atramentarius Simon (family Chactidae), whose venoms show
low toxicity towards vertebrates, frequently envenom humans in the highly populated Guayas and Pichincha
provinces. This work also updates the local scorpion faunal endemicity (74.5 %) and its geographical distribution,
and reviews available medical/biochemical information on each species in the light of the increasing problem of
scorpionism in the country. A proposal is hereby put forward to classify the Ecuadorian scorpions based on their
potential medical importance

Understanding how biotic interactions shape the genomes of the interacting species is a long-sought goal of evolutionary biology that has been hampered by the scarcity of tractable systems in which specific genomic features can be linked... more

Understanding how biotic interactions shape the genomes of the interacting species is a long-sought goal of evolutionary biology that has been hampered by the scarcity of tractable systems in which specific genomic features can be linked to complex phenotypes involved in interspecific interactions. In this review we present the compelling case of evolved resistance to the toxic challenge of venomous or poisonous animals as one such system. Animal venoms and poisons can be comprised of few or of many individual toxins. Here we show that resistance to animal toxins has evolved multiple times across metazoans, although it has been documented more often in phyla that feed on chemically-armed animals than in prey of venomous predators. We review three types of gene-product based resistance: 1) toxin scavenging, where molecules produced by the envenomed organism bind and inactivate the toxins; 2) target-site insensitivity, including landmark cases of convergent changes that make the molecules normally targeted by animal toxins refractory, and; 3) off-target repurposing, where envenomed organisms overcome toxicity by exploiting the function of toxins to alter their physiological effect. We finish by discussing the evolutionary processes that likely played a role in the origin and maintenance of toxin resistance. We conclude that antagonistic interactions involving poisonous or venomous animals are unparalleled models for investigating microevolutionary processes involved in coevolution and linking them to macroevolutionary patterns.

Background: The explosive radiation and diversification of the advanced snakes (superfamily Colubroidea) was associated with changes in all aspects of the shared venom system. Morphological changes included the partitioning of the mixed... more

Background: The explosive radiation and diversification of the advanced snakes (superfamily Colubroidea) was associated with changes in all aspects of the shared venom system. Morphological changes included the partitioning of the mixed ancestral glands into two discrete glands devoted for production of venom or mucous respectively, as well as changes in the location, size and structural elements of the venom-delivering teeth. Evidence also exists for homology among venom gland toxins expressed across the advanced snakes. However, despite the evolutionary novelty of snake venoms, in-depth toxin molecular evolutionary history reconstructions have been mostly limited to those types present in only two front-fanged snake families, Elapidae and Viperidae. To have a broader understanding of toxins shared among extant snakes, here we first sequenced the transcriptomes of eight taxonomically diverse rear-fanged species and four key viperid species and analysed major toxin types shared across the advanced snakes. Results: Transcriptomes were constructed for the following families and species: Colubridae-Helicops leopardinus, Heterodon nasicus, Rhabdophis subminiatus; Homalopsidae-Homalopsis buccata; Lamprophiidae-Malpolon monspessulanus, Psammophis schokari, Psammophis subtaeniatus, Rhamphiophis oxyrhynchus; and Viperidae-Bitis atropos, Pseudocerastes urarachnoides, Tropidolaeumus subannulatus, Vipera transcaucasiana. These sequences were combined with those from available databases of other species in order to facilitate a robust reconstruction of the molecular evolutionary history of the key toxin classes present in the venom of the last common ancestor of the advanced snakes, and thus present across the full diversity of colubroid snake venoms. In addition to differential rates of evolution in toxin classes between the snake lineages, these analyses revealed multiple instances of

Enzyme-cleaved antibodies are used widely for the treatment of envenoming. Such products should comprise only ‘highly pure’ immunoglobulin fragments since Fc or other contaminating protein fragments or their aggregates may lead to side... more

Enzyme-cleaved antibodies are used widely for the treatment of envenoming. Such products should comprise only ‘highly pure’ immunoglobulin fragments since Fc or other contaminating protein fragments or their aggregates may lead to side effects. The digestion of ovine antiserum and its purified IgG were investigated using pepsin and trypsin. Trypsin was effective at digesting purified IgG but unsuitable for the direct digestion of serum. In contrast, pepsin was highly effective at digesting all unwanted serum components to low molecular weight (≤13 kDa) fragments while leaving the ~100-kDa F(ab′)2 intact. The optimum pH for pepsin digestion was between 3.25 and 3.50. The effects of salt concentration and pH on the digestion products were investigated by size exclusion chromatography under various conditions, which revealed a pH-dependent aggregation of some of the low molecular weight Fc and non-IgG fragments. These high molecular weight aggregates were not shown by SDS-PAGE. Unwanted low molecular weight fragments could be removed simply by diafiltration with a 30-kDa nominal molecular weight cutoff membrane and piperazine buffer (containing 150 mM NaCl, pH 6), leaving an F(ab′)2 solution contaminated only with some pepsin and a small amount of the aggregated low molecular weight fragments. These highly acidic contaminants were then removed easily using an anion exchange column and the F(ab′)2 produced following a subsequent concentration step was essentially free from pepsin and aggregates with a purity of over 96% and a yield of 19.3 g F(ab′)2/l serum. This novel, high yield method for processing serum to highly pure F(ab′)2 avoids salt precipitation and centrifugation and should be suitable for large-scale production.

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated... more

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. The...

Serum Anti Ular Bisa (SABU) is the only snake antivenom produced locally in Indonesia; however, its effectiveness has not been rigorously evaluated. This study aimed to assess the protein composition and neutralization efficacy of SABU.... more

Serum Anti Ular Bisa (SABU) is the only snake antivenom produced locally in Indonesia; however, its effectiveness has not been rigorously evaluated. This study aimed to assess the protein composition and neutralization efficacy of SABU. SDS polyacrylamide gel electrophoresis, size-exclusion liquid chromatography and shotgun proteomics revealed that SABU consists of F(ab') 2 but a significant amount of dimers, protein aggregates and contaminant albumins. SABU moderately neutralized Calloselasma rhodostoma venom (potency of 12.7 mg venom neutralized per ml antivenom, or 121.8 mg venom per g antivenom protein) and Bungarus fasciatus venom (0.9 mg/ml; 8.5 mg/g) but it was weak against the venoms of Naja sputatrix (0.3 mg/ml; 2.9 mg/g), Naja sumatrana (0.2 mg/ml; 1.8 mg/g) and Bungarus candidus (0.1 mg/ml; 1.0 mg/g). In comparison, NPAV, the Thai Neuro Polyvalent Antivenom, outperformed SABU with greater potencies against the venoms of N. sputatrix (0.6 mg/ml; 8.3 mg/g), N. sumatrana (0.5 mg/ml; 7.1 mg/g) and B. candidus (1.7 mg/ml; 23.2 mg/g). The inferior efficacy of SABU implies that a large antivenom dose is required clinically for effective treatment. Besides, the antivenom contains numerous impurities e.g., albumins that greatly increase the risk of hypersensitivity. Together, the findings indicate that the production of SABU warrants further improvement. Indonesia is a vast archipelago extending more than 5000 km from east to west in the equatorial region. Its rich herpetofauna includes more than 10 venomous snake species that distribute in two major ecozones divided by the Wallace's line. On the eastern side of the Wallace's line on the Sahul Shelf, there are the Australian elapid fauna, while snakes inhabiting islands west of the Wallace's line on the Sunda Shelf are mostly common or similar species found in the Malay Archipelago. Java and Sumatra are two huge, densely populated islands on the Sunda Shelf, and they are also natural habitat to many Indonesian snakes. In these islands, the spitting cobras (Naja sputatrix in Java and Lesser Sunda; Naja sumatrana in Sumatra and Kalimantan), the Malayan krait (Bungarus candidus) (Sumatra and Java) and the Malayan pit viper (Calloselasma rhodostoma in Java) are listed under WHO Category 1 of medical importance 1. Other species of medical importance include the Russell's viper (Daboia siamensis) and green pit vipers of Trimeresurus complex, the geographical distributions of which are relatively limited in the country. Although snakebite is likely affecting the Indonesian population at a large scale 1 , unfortunately, comprehensive epidemiological study of snakebite in this country remains extremely scarce 2. Snakebite envenomation has been aptly described as a disease of poverty that affects heavily the poor or rural population in the developing tropical countries 3,4. Prior to the year 2015, it was obscurely listed under " Other Categories " of the Neglected Tropical Diseases by the WHO, lacking systematic attention and official global support program. In 2015, the world saw the de-listing of this critical health problem from the mentioned list of WHO Neglected Tropical Diseases. In fact, the persistent underestimation of snakebite morbidity and mortality has made it the most neglected condition among many other diseases in the tropics 5 , and toxinology experts have called on WHO and governments to re-establish snakebite as a neglected tropical disease 6. Regional toxinologists are also taking up proactive approaches to tackle the various challenges associated with snakebite envenomation.

Recientemente la fauna de equinodermos fue catalogada en el Sistema Arrecifal Lobos-Tuxpan (SALT), sin embargo faltaron por ser explorados los arrecifes del polígono Tuxpan, por lo que el objetivo del presente trabajo fue registrar la... more

Recientemente la fauna de equinodermos fue catalogada en el Sistema Arrecifal Lobos-Tuxpan (SALT), sin embargo faltaron por ser explorados los arrecifes del polígono Tuxpan, por lo que el objetivo del presente trabajo fue registrar la riqueza de especies de los arrecifes Tanhuijo, Enmedio y Tuxpan a fin de completar la lista faunística de equinodermos del SALT. Entre el 2015-2016 se realizaron muestreos en la planicie arrecifal y en las pendientes de sotavento y barlovento revisando minuciosamente varios hábitats bentónicos: corales masivos, montículos de coral muerto con algas, debajo de rocas, arena con escombros y pastos marinos, así también en macroalgas y esponjas. Se registraron un total de 40 especies de equinodermos, las clases más representativas en número de especies fueron Ophiuroidea y Echinoidea con 14 y 11 especies respectivamente. Al menos el 67.5% de las especies se registraron en los tres arrecifes estudiados. Se registró mayor riqueza de equinodermos en el arrecife Enmedio con 39 especies. En general, los hábitats más comunes donde se observaron equinodermos fueron en corales masivos, rocas coralinas con algas y debajo de rocas. Se añaden nueve registros más a la fauna de equinodermos del SALT, incrementándose el listado sistemático a 51 especies para la zona norte de Veracruz. En el SALT, los equinodermos constituyen el tercer grupo faunístico mejor estudiado después de peces y corales Palabras ClaVe: lista faunística, asociaciones ofiuras-esponjas, hábitats bentónicos, Veracruz.

Millions of years of evolution have fine-tuned the ability of venom peptides to rapidly incapacitate both prey and potential predators. Toxicofera reptiles are characterized by serous-secreting mandibular or maxillary glands with... more

Millions of years of evolution have fine-tuned the ability of venom peptides to rapidly incapacitate both prey and potential predators. Toxicofera reptiles are characterized by serous-secreting mandibular or maxillary glands with heightened levels of protein expression. These glands are the core anatomical components of the toxicoferan venom system, which exists in myriad points along an evolutionary continuum. Neofunctionalisation of toxins is facilitated by positive selection at functional hotspots on the ancestral protein and venom proteins have undergone dynamic diversification in helodermatid and varanid lizards as well as advanced snakes. A spectacular point on the venom system continuum is the long-glanded blue coral snake (Calliophis bivirgatus), a specialist feeder that preys on fast moving, venomous snakes which have both a high likelihood of prey escape but also represent significant danger to the predator itself. The maxillary venom glands of C. bivirgatus extend one quarter of the snake's body length and nestle within the rib cavity. Despite the snake's notoriety its venom has remained largely unstudied. Here we show that the venom uniquely produces spastic paralysis, in contrast to the flaccid paralysis typically produced by neurotoxic snake venoms. The toxin responsible, which we have called calliotoxin (δ-elapitoxin-Cb1a), is a three-finger toxin (3FTx). Calliotoxin shifts the voltage-dependence of Na V 1.4 activation to more hyperpolarised potentials, inhibits inactivation, and produces large ramp currents, consistent with its profound effects on contractile force in an isolated skeletal muscle preparation. Voltage-gated sodium channels (Na V) are a particularly attractive pharmacological target as they are involved in almost all physiological processes including action potential generation and conduction. Accordingly, venom peptides that interfere with Na V function provide a key defensive and predatory advantage to a range of invertebrate venomous species including cone snails, scorpions, spiders, and anemones. Enhanced activation or delayed inactivation of sodium channels by toxins is associated with the extremely rapid onset of tetanic/excitatory paralysis in envenomed prey animals. A strong selection pressure exists for the evolution of such toxins where there is a high chance of prey escape. However, despite their prevalence in other venomous species, toxins causing delay of sodium channel inhibition have never previously been described in vertebrate venoms. Here we show that Na V modulators, convergent with those of invertebrates, have evolved in the venom of the long-glanded coral snake. Calliotoxin represents a functionally novel class of 3FTx and a structurally novel class of Na V toxins that will provide significant insights into the pharmacology and physiology of Na V. The toxin represents a remarkable case of functional convergence between invertebrate and vertebrate venom systems in response to similar selection pressures. These results underscore the dynamic evolution of the Toxicofera reptile system and reinforces the value of using evolution as a roadmap for biodiscovery.

Saw-scaled vipers (genus Echis) are one of the leading causes of snakebite morbidity and mortality in parts of Sub-Saharan Africa, the Middle East, and vast regions of Asia, constituting a public health burden exceeding that of almost any... more

Saw-scaled vipers (genus Echis) are one of the leading causes of snakebite morbidity and mortality in parts of Sub-Saharan Africa, the Middle East, and vast regions of Asia, constituting a public health burden exceeding that of almost any other snake genus globally. Venom-induced consumption coagulopathy, owing to the action of potent procoagulant toxins, is one of the most relevant clinical manifestations of envenomings by Echis spp. Clinical experience and prior studies examining a limited range of venoms and restricted antivenoms have demonstrated for some antivenoms an extreme lack of antivenom cross-reactivity between different species of this genus, sometimes resulting in catastrophic treatment failure. This study undertook the most comprehensive testing of Echis venom effects upon the coagulation of human plasma, and also the broadest examination of antivenom potency and cross-reactivity, to-date. 10 Echis species/populations and four antivenoms (two African, two Asian) were studied. The results indicate that the venoms are, in general, potently procoagulant but that the relative dependence on calcium or phospholipid cofactors is highly variable. Additionally, three out of the four antivenoms tested demonstrated only a very narrow taxonomic range of effectiveness in preventing coagulopathy, with only the SAIMR antivenom displaying significant levels of cross-reactivity. These results were in conflict with previous studies using prolonged preincubation of antivenom with venom to suggest effective crossreactivity levels for the ICP Echi-Tab antivenom. These findings both inform upon potential clinical effects of envenomation in humans and highlight the extreme limitations of available treatment. It is hoped that this will spur efforts into the development of antivenoms with more comprehensive coverage for bites not only from wild snakes but also from specimens widely kept in zoological collections.

Phospholipases A2 enzymes are found in many mammalian tissues and in animal venoms. Those present in bee venom (bvPLA2) and snake venom (svPLA2) have been studied more particularly for their biological activities of interest. Although... more

Phospholipases A2 enzymes are found in many mammalian tissues and in animal venoms. Those present in bee venom (bvPLA2) and snake venom (svPLA2) have been studied more particularly for their biological activities of interest. Although they belong to the same family of secreted PLA2 (sPLA2), bvPLA2 and svPLA2 differ from a structural and functional point of view. In this review, we describe the morphological characteristics of these two enzymes and the structural determinants that govern their functions. After describing their cytotoxicity, we compared their biological activities, including antimicrobial, anti-tumor, anti-inflammatory, anti-neurodegenerative, and anti-nociceptive effects. In addition, we highlighted their therapeutical applications and deduced that bvPLA2 has better potential than svPLA2 in biotechnological and pharmaceutical innovations.

Snakebite is a neglected tropical disease that disproportionately affects the poor. Antivenom is the only specific and effective treatment for snakebite, but its distribution is severely limited by several factors, including the... more

Snakebite is a neglected tropical disease that disproportionately affects the poor. Antivenom is the only specific and effective treatment for snakebite, but its distribution is severely limited by several factors, including the prohibitive cost of some products. Papua New Guinea (PNG) is a snakebite hotspot but the high costs of Australian antivenoms (thousands of dollars per treatment) makes it unaffordable in PNG. A more economical taipan antivenom has recently been developed at the Instituto Clodomiro Picado (ICP) in Costa Rica for PNG and is currently undergoing clinical trials for the treatment of envenomations by coastal taipans (Oxyuranus scutellatus). In addition to potentially having the capacity to neutralise the effects of envenomations of non-PNG taipans, this antivenom may have the capacity to neutralise coagulotoxins in venom from closely related brown snakes (Pseudonaja spp.) also found in PNG. Consequently, we investigated the cross-reactivity of taipan antivenom across the venoms of all Oxyuranus and Pseudonaja species. In addition, to ascertain differences in venom biochemistry that influence variation in antivenom efficacy, we tested for relative cofactor dependence. We found that the new ICP taipan antivenom exhibited high selectivity for Oxyuranus venoms and only low to moderate cross-reactivity with any Pseudonaja venoms. Consistent with this genus level distinction in antivenom efficacy were fundamental differences in the venom biochemistry. Not only were the Pseudonaja venoms significantly more procoagulant, but they were also much less dependent upon the cofactors calcium and phospholipid. There was a strong correlation between antivenom efficacy, clotting time and cofactor dependence. This study sheds light on the structure-function relationships of the procoagulant toxins within these venoms and may have important clinical implications including for the design of next-generation antivenoms.

Lancehead pit-vipers (Bothrops genus) are an extremely diverse and medically important group responsible for the greatest number of snakebite envenomations and deaths in South America. Bothrops atrox (common lancehead), responsible for... more

Lancehead pit-vipers (Bothrops genus) are an extremely diverse and medically important group responsible for the greatest number of snakebite envenomations and deaths in South America. Bothrops atrox (common lancehead), responsible for majority of snakebites and related deaths within the Brazilian Amazon, is a highly adaptable and widely distributed species, whose venom variability has been related to several factors, including geographical distribution and habitat type. This study examined venoms from four B. atrox populations (Belterra and Santarém, PA; Pres. Figueiredo, AM and São Bento, MA), and two additional Bothrops species (B. jararaca and B. neuwiedi) from Southeastern region for their coagulotoxic effects upon different plasmas (human, amphibian, and avian). The results revealed inter– and intraspecific variations in coagulotoxicity, including distinct activities between the three plasmas, with variations in the latter two linked to ecological niche occupied by the snakes. Also examined were the correlated biochemical mechanisms of venom action. Significant variation in the relative reliance upon the cofactors calcium and phospholipid were revealed, and the relative dependency did not significantly correlate with potency. Relative levels of Factor X or prothrombin activating toxins correlated with prey type and prey escape potential. The antivenom was shown to perform better in neutralising prothrombin activation activity than neutralising Factor X activation activity. Thus, the data reveal new information regarding the evolutionary selection pressures shaping snake venom evolution, while also having significant implications for the treatment of the envenomed patient. These results are, therefore, an intersection between evolutionary biology and clinical medicine. Key Contribution: Substantial variations in the procoagulant activity of the Bothrops genus—the most medically important snake group in South America—were documented; including intra-specific venom variations across B. atrox populations. This study provides important insights the role of prey type in shaping venom evolution and about relative neutralisation by antivenoms.

Despite extensive study of poisonous and venomous organisms and the toxins they produce, a review of the literature reveals inconsistency and ambiguity in the definitions of 'poison' and 'venom'. These two terms are frequently conflated... more

Despite extensive study of poisonous and venomous organisms and the toxins they produce, a review of the literature reveals inconsistency and ambiguity in the definitions of 'poison' and 'venom'. These two terms are frequently conflated with one another, and with the more general term, 'toxin.' We therefore clarify distinctions among three major classes of toxins (biological, environmental, and anthropogenic or man-made), evaluate prior definitions of venom which differentiate it from poison, and propose more rigorous definitions for poison and venom based on differences in mechanism of delivery. We also introduce a new term, 'toxungen', thereby partitioning toxic biological secretions into three categories: poisons lacking a delivery mechanism, i.e. ingested, inhaled, or absorbed across the body surface; toxungens delivered to the body surface without an accompanying wound; and venoms, delivered to internal tissues via creation of a wound. We further propose a system to classify toxic organisms with respect to delivery mechanism (absent versus present), source (autogenous versus heterogenous), and storage of toxins (aglandular versus glandular). As examples, a frog that acquires toxins from its diet, stores the secretion within cutaneous glands, and transfers the secretion upon contact or ingestion would be heteroglandular-poisonous; an ant that produces its own toxins, stores the secretion in a gland, and sprays it for defence would be autoglandular-toxungenous; and an anemone that produces its own toxins within specialized cells that deliver the secretion via a penetrating wound would be autoaglandular-venomous. Adoption of our scheme should benefit our understanding of both proximate and ultimate causes in the evolution of these toxins.

A B S T R A C T Night adders (Causus species within the Viperidae family) are amphibian specialists and a common source of snakebite in Africa. Some species are unique in that they have the longest venom glands of any viper, extending... more

A B S T R A C T Night adders (Causus species within the Viperidae family) are amphibian specialists and a common source of snakebite in Africa. Some species are unique in that they have the longest venom glands of any viper, extending approximately 10% of the body length. Despite their potential medical importance and evolutionary novelty, their venom has received almost no research attention. In this study, venoms from a short-glanded species (C. lichtensteinii) and from a long-glanded species (C. rhombeatus) were compared using a series of proteomic and bioactivity testing techniques to investigate and compare the toxin composition and functioning of the venoms of these two species. Both C. rhombeatus and C. lichtensteinii were similar in overall venom composition and inhibition of blood coagulation through non-clotting proteolytic cleavage of fibrinogen. While the 1D gel profiles were very similar to each other in the toxin types present, 2D gel analyses revealed isoformic differences within each toxin classes. This variation was congruent with differential efficacy of South African Institute for Medical Research snake polyvalent antivenom, with C. lichtensteinii unaffected at the dose tested while C. rhombeatus was moderately but significantly neutralized. Despite the variation within toxin classes, the similarity in overall venom biochemistry suggests that the selection pressure for the evolution of long glands served to increase venom yield in order to subjugate proportionally large anurans as a unique form of niche partitioning, and is not linked to significant changes in venom function. These results not only contribute to the body of venom evolution knowledge but also highlight the limited clinical management outcomes for Causus envenomations.

A B S T R A C T A paradigm of venom research is adaptive evolution of toxins as part of a predator-prey chemical arms race. This study examined differential co-factor dependence, variations relative to dietary preference, and the impact... more

A B S T R A C T A paradigm of venom research is adaptive evolution of toxins as part of a predator-prey chemical arms race. This study examined differential co-factor dependence, variations relative to dietary preference, and the impact upon relative neutralisation by antivenom of the procoagulant toxins in the venoms of a clade of Australian snakes. All genera were characterised by venoms rich in factor Xa which act upon endogenous prothrombin. Examination of toxin sequences revealed an extraordinary level of conservation, which indicates that adaptive evolution is not a feature of this toxin type. Consistent with this, the venoms did not display differences on the plasma of different taxa. Examination of the prothrombin target revealed endogenous blood proteins are under extreme negative selection pressure for diversification, this in turn puts a strong negative selection pressure upon the toxins as sequence diversification could result in a drift away from the target. Thus this study reveals that adaptive evolution is not a consistent feature in toxin evolution in cases where the target is under negative selection pressure for diversification. Consistent with this high level of toxin conservation, the antivenom showed extremely high-levels of cross-reactivity. There was however a strong statistical correlation between relative degree of phospholipid-dependence and clotting time, with the least dependent venoms producing faster clotting times than the other venoms even in the presence of phospholipid. The results of this study are not only of interest to evolutionary and ecological disciplines, but also have implications for clinical toxinology.

Australia is the stronghold of the front-fanged venomous snake family Elapidae. The Australasian elapid snake radiation, which includes approximately 100 terrestrial species in Australia, as well as Melanesian species and all the world's... more

Australia is the stronghold of the front-fanged venomous snake family Elapidae. The Australasian elapid snake radiation, which includes approximately 100 terrestrial species in Australia, as well as Melanesian species and all the world's sea snakes, is less than 12 million years old. The incredible phenotypic and ecological diversity of the clade is matched by considerable diversity in venom composition. The clade's evolutionary youth and dynamic evolution should make it of particular interest to toxinologists, however, the majority of species, which are small, typically inoffensive, and seldom encountered by non-herpetologists, have been almost completely neglected by researchers. The present study investigates the venom composition of 28 species proteomically, revealing several interesting trends in venom composition, and reports, for the first time in elapid snakes, the existence of an ontogenetic shift in the venom composition and activity of brown snakes (Pseudonaja sp.). Trends in venom composition are compared to the snakes' feeding ecology and the paper concludes with an extended discussion of the selection pressures shaping the evolution of snake venom.

Centruroides tecomanus is a medically important scorpion of the state of Colima (Mexico). This communication reports the identification of venom components of this scorpion with biological activity over insects/crickets (Acheta... more

Centruroides tecomanus is a medically important scorpion of the state of Colima (Mexico). This
communication reports the identification of venom components of this scorpion with biological activity
over insects/crickets (Acheta domestica), crustaceans/fresh water shrimps (Cambarellus montezumae), and
mammalians/mice (Mus musculus, strain CD1). It also describes the pharmacological effects on cell lines
in culture (L5178Y cells, HeLa cells, HuTu cells and Jurkat E6-1 cells), as well as on several types of
bacteria (see below). The soluble venom of this scorpion was fractionated by high-performance liquid
chromatography (HPLC) and collected separately in twelve independent fractions collected over 60 min
run (5 min time apart each other). The HPLC components of fraction VII were lethal to all three species
used for assay. The IVth fraction had a toxic effect on freshwater shrimps. In this species, fractions VI, VII
and VIII were all lethal. For crickets, fractions V and VI were toxic and fraction VII was lethal. In mouse,
the lethal components were found in fraction VII, whereas fraction VIII was toxic, but not lethal, at the
doses assayed. The molecular weight of peptides from the various group of fractions were identified by
mass spectrometry determination. Components lethal to mice showed molecular weights from 7013 to
7487 Da. Two peptides were obtained in homogeneous form and shown to be lethal to the three species
of animal used for assay. The soluble venom tested on L5178Y cell line survival was shown to be cytotoxic,
at 10e100 mg/mL concentration, when compared to control murine splenocytes (p ¼ 0.007). The
soluble venom applied to Hela, Hutu and Jurkat cell lines did not show cytotoxic effects at these concentrations.
On the contrary, it seems to have a proliferative effect. However the HPLC fractions I, III, VI
and XII do have a cytotoxic effect on Jurkat E06-1 cells in culture at 200 mg/mL concentration. The
antimicrobial activity of the venom fractions on Staphylococcus aureus (gram-positive), Escherichia coli,
Pseudomonas aeruginosa y Salmonella spp (gram-negative) was measured, using the liquid inhibition
growth system. The four strains of bacteria used were susceptible to fractions III and IV, affecting all four
bacterial strains at concentrations below 5 mg/mL.

It has been previously shown that octopus venoms contain novel tachykinin peptides that despite being isolated from an invertebrate, contain the motifs characteristic of vertebrate tachykinin peptides rather than being more like... more

It has been previously shown that octopus venoms contain novel tachykinin peptides that despite being isolated from an invertebrate, contain the motifs characteristic of vertebrate tachykinin peptides rather than being more like conventional invertebrate tachykinin peptides. Therefore, in this study we examined the effect of three variants of octopus venom tachykinin peptides on invertebrate and vertebrate tissues. While there were differential potencies between the three peptides, their relative effects were uniquely consistent between invertebrate and vertebrae tissue assays. The most potent form (OCT-TK-III) was not only the most anionically charged but also was the most structurally stable. These results not only reveal that the interaction of tachykinin peptides is more complex than previous structure-function theories envisioned, but also reinforce the fundamental premise that animal venoms are rich resources of novel bioactive molecules, which are useful investigational ligands and some of which may be useful as lead compounds for drug design and development.

The use of California harvester ants (Pogonomyrmex californicus) for visionary and therapeutic ends was an important but poorly-documented tradition in native south-central California. In this brief report, a confirmation of the... more

The use of California harvester ants (Pogonomyrmex californicus) for visionary and therapeutic ends was an important but poorly-documented tradition in native south-central California. In this brief report, a confirmation of the taxonomic identity of the red ant species used in Califomia is presented, and the descriptive record of its use is supplemented with additional ethnographic accounts. This taxonomic identification of this species is of particular importance, as visionary red ant ingestion provides the only well-documented case of the widespread use of an insect as an hallucinogenic agent.

The Asian genus Boiga (Colubridae) is among the better studied non-front-fanged snake lineages, because their bites have minor, but noticeable, effects on humans. Furthermore, B. irregularis has gained worldwide notoriety for successfully... more

The Asian genus Boiga (Colubridae) is among the better studied non-front-fanged snake lineages, because their bites have minor, but noticeable, effects on humans. Furthermore, B. irregularis has gained worldwide notoriety for successfully invading Guam and other nearby islands with drastic impacts on the local bird populations. One of the factors thought to allow B. irregularis to become such a noxious pest is irditoxin, a dimeric neurotoxin composed of two three-finger toxins (3FTx) joined by a covalent bond between two newly evolved cysteines. Irditoxin is highly toxic to diapsid (birds and reptiles) prey, but roughly 1000 × less potent to synapsids (mammals). Venom plays an important role in the ecology of all species of Boiga, but it remains unknown if any species besides B. irregularis produce irditoxin-like dimeric toxins. In this study, we use transcriptomic analyses of venom glands from five species [B. cynodon, B. dendrophila dendrophila, B. d. gemmicincta, B. irregularis (Brisbane population), B. irregularis (Sulawesi population), B. nigriceps, B. trigonata] and proteomic analyses of B. d. dendrophila and a representative of the sister genus Toxicodryas blandingii to investigate the evolutionary history of 3FTx within Boiga and its close relative. We found that 92.5% of Boiga 3FTx belong to a single clade which we refer to as denmotoxin-like because of the close relation between these toxins and the monomeric denmotoxin according to phy-logenetic, sequence clustering, and protein similarity network analyses. We show for the first time that species beyond B. irregularis secrete 3FTx with additional cysteines in the same position as both the A and B subunits of irditoxin. Transcripts with the characteristic mutations are found in B. d. dendrophila, B. d. gemmicincta, B. irregularis (Brisbane population), B. irregularis (Sulawesi population), and B. nigriceps. These results are confirmed by proteomic analyses that show direct evidence of dimerization within the venom of B. d. dendrophila, but not T. blandingii. Our results also suggest the possibility of novel dimeric toxins in other genera such as Telescopus and Trimorphodon. All together, this suggests that the origin of these peculiar 3FTx is far earlier than was appreciated and their evolutionary history has been complex.

As trophic adaptations, rattlesnake venoms can vary in composition depending on several intrinsic and extrinsic factors. Ontogenetic changes in venom composition have been documented for numerous species, but little is known of the... more

As trophic adaptations, rattlesnake venoms can vary in composition depending on several intrinsic and extrinsic factors. Ontogenetic changes in venom composition have been documented for numerous species, but little is known of the potential age-related changes in many rattlesnake species found in México. In the current study, venom samples collected from adult and neonate Crotalus polystictus from Estado de México were subjected to enzymatic and electrophoretic analyses, toxicity assays (LD 50), and MALDI-TOF mass spectrometry, and a pooled sample of adult venom was analyzed by shotgun proteomics. Electrophoretic profiles of adult males and females were quite similar, and only minor sex-based variation was noted. However, distinct differences were observed between venoms from adult females and their neonate offspring. Several prominent bands, including P-I and P-III snake venom metalloproteinases (SVMPs) and disintegrins (confirmed by MS/MS) were present in adult venoms and absent/greatly reduced in neonate venoms. Age-dependent differences in SVMP, kallikrein-like, phospholipase A 2 (PLA 2), and L-amino acid oxidase (LAAO) activity levels were confirmed by enzymatic activity assays, and like many other rattlesnake species, venoms from adult snakes have higher SVMP activity than neonate venoms. Conversely, PLA 2 activity was approximately 2.5 × greater in venoms from neonates, likely contributing to the increased toxicity (neonate venom LD 50 = 4.5 µg/g) towards non-Swiss albino mice when compared to adult venoms (LD 50 = 5.5 µg/g). Thrombin-like (TLE) and phosphodiesterase activities did not vary significantly with age. A significant effect of sex (between adult male and adult female venoms) was also observed for SVMP, TLE, and LAAO activities. Analysis of pooled adult venom by LC-MS/MS identified 14 toxin protein families, dominated by bradykinin-inhibitory peptides, SVMPs (P-I, P-II and P-III), disintegrins, PLA 2 s, C-type-lectins, CRiSPs, serine proteinases, and LAAOs (96% of total venom proteins). Neonate and adult C. polystictus in this population consume almost exclusively mammals, suggesting that age-based differences in composition are related to physical differences in prey (e.g., surface-to-volume ratio differences) rather than taxonomic differences between prey. Venoms from adult C. polystictus fit a Type I pattern (high SVMP activity, lower toxicity), which is characteristic of many larger-bodied rattlesnakes of North America. Key Contribution: We provide a detailed analysis of the venom of a rattlesnake that occupies mid-elevation habitat in México. Venoms from neonate and adult Crotalus polystictus show distinct differences in SVMP, kallikrein-like, LAAO, and PLA 2 activities and disintegrin content. Venomics of pooled adult C. polystictus venom identified many major venom components that are common in rattlesnake venoms, with bradykinin-inhibitory peptide constituting 36% of the venom proteome. Crotalus polystictus shows a pattern of venom ontogeny similar to other rattlesnakes that produce a type I venom.

Pseudechis (black snakes) is an Australasian elapid snake genus that inhabits much of mainland Australia, with two representatives confined to Papua New Guinea. The present study is the first to analyse the venom of all 9 described... more

Pseudechis (black snakes) is an Australasian elapid snake genus that inhabits much of mainland Australia, with two representatives confined to Papua New Guinea. The present study is the first to analyse the venom of all 9 described Pseudechis species (plus one undescribed species) to investigate the evolution of venom composition and functional activity. Proteomic results demonstrated that the typical Pseudechis venom profile is dominated by phospholipase A 2 toxins. Strong cytotoxicity was the dominant function for most species. P. porphyriacus, the most basal member of the genus, also exhibited the most divergent venom composition, being the only species with appreciable amounts of procoagulant toxins. The relatively high presence of factor Xa recovered in P. porphyriacus venom may be related to a predominantly amphibian diet. Results of this study provide important insights to guide future ecological and toxinological investigations.

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated... more

While snake venoms have been the subject of intense study, comparatively little work has been done on lizard venoms. In this study, we have examined the structural and functional diversification of anguimorph lizard venoms and associated toxins, and related these results to dentition and predatory ecology. Venom composition was shown to be highly variable across the 20 species of Heloderma, Lanthanotus, and Varanus included in our study. While kallikrein enzymes were ubiquitous, they were also a particularly multifunctional toxin type, with differential activities on enzyme substrates and also ability to degrade alpha or beta chains of fibrinogen that reflects structural variability. Examination of other toxin types also revealed similar variability in their presence and activity levels. The high level of venom chemistry variation in varanid lizards compared to that of helodermatid lizards suggests that venom may be subject to different selection pressures in these two families. These results not only contribute to our understanding of venom evolution but also reveal anguimorph lizard venoms to be rich sources of novel bioactive molecules with potential as drug design and development lead compounds.

The " function debate " in the philosophy of biology and the " venom debate " in the science of toxinology are conceptually related. Venom systems are complex multifunctional traits that have evolved independently numerous times... more

The " function debate " in the philosophy of biology and the " venom debate " in the science of toxinology are conceptually related. Venom systems are complex multifunctional traits that have evolved independently numerous times throughout the animal kingdom. No single concept of function, amongst those popularly defended, appears adequate to describe these systems in all their evolutionary contexts and extant variations. As such, a pluralistic view of function, previously defended by some philosophers of biology, is most appropriate. Venom systems, like many other functional traits, exist in nature as points on a continuum and the boundaries between " venomous " and " non-venomous " species may not always be clearly defined. This paper includes a brief overview of the concept of function, followed by in-depth discussion of its application to venom systems. A sound understanding of function may aid in moving the venom debate forward. Similarly, consideration of a complex functional trait such as venom may be of interest to philosophers of biology.

Toxic weaponry in the form of venom and poison has evolved in most groups of animals, including all four major lineages of tetrapods. Moreover, the evolution of such traits has been linked to several key aspects of the biology of toxic... more

Toxic weaponry in the form of venom and poison has evolved in most groups of animals, including all four major lineages of tetrapods. Moreover, the evolution of such traits has been linked to several key aspects of the biology of toxic animals including life-history and diversification. Despite this, attempts to investigate the macroevolutionary patterns underlying such weaponry are lacking. In this study we analyse patterns of venom and poison evolution across reptiles, amphibians, mammals, and birds using a suite of phylogenetic comparative methods. We find that each major lineage has a characteristic pattern of trait evolution, but mammals and reptiles evolve under a surprisingly similar regime, whilst that of amphibians appears to be particularly distinct and highly contrasting compared to other groups. Our results also suggest that the mechanism of toxin acquisition may be an important distinction in such evolutionary patterns; the evolution of biosynthesis is far less dynamic than that of sequestration of toxins from the diet. Finally, contrary to the situation in amphibians, other tetrapod groups show an association between the evolution of toxic weaponry and higher diversification rates. Taken together, our study provides the first broad-scale analysis of macroevolutionary patterns of venom and poison throughout tetrapods.