Adaptive trade-offs between vertebrate defence and insect predation drive Amazonian ant venom evolution.

Stinging ants have diversified into various ecological niches, and selective pressures may have contributed to shape the composition of their venom. To explore the drivers underlying venom variation in ants, we sampled 15 South American rainforest species and recorded a range of traits, including ecology, morphology and venom bioactivities. Principal component analysis of both morphological and venom bioactivity traits reveals that stinging ants display two functional strategies where species have evolved towards either an exclusively offensive venom or a multi-functional venom.

Exaptation of an evolutionary constraint enables behavioural control over the composition of secreted venom in a giant centipede.

Venoms are biochemical arsenals that have emerged in numerous animal lineages, where they have co-evolved with morphological and behavioural traits for venom production and delivery. In centipedes, venom evolution is thought to be constrained by the morphological complexity of their venom glands due to physiological limitations on the number of toxins produced by their secretory cells. Here we show that the uneven toxin expression that results from these limitations have enabled Scolopendra morsitans to regulate the composition of their secreted venom despite the lack of gross morphologically complex venom glands.

χ-Conotoxins are an Evolutionary Innovation of Mollusk-Hunting Cone Snails as a Counter-Adaptation to Prey Defense.

Mollusk-hunting (molluscivorous) cone snails belong to a monophyletic group in Conus, a genus of venomous marine snails. The molluscivorous lineage evolved from ancestral worm-hunting (vermivorous) snails ∼18 Ma. To enable the shift to a molluscivorous lifestyle, molluscivorous cone snails must solve biological problems encountered when hunting other gastropods, namely: (i) preventing prey escape and (ii) overcoming the formidable defense of the prey in the form of the molluscan shell, a problem unique to molluscivorous Conus.

Venom exaptation and adaptation during the trophic switch to blood-feeding by kissing bugs.

Kissing bugs are known to produce anticoagulant venom that facilitates blood-feeding. However, it is unknown how this saliva evolved and if the venom produced by the entomophagous ancestors of kissing bugs would have helped or hindered the trophic shift. In this study, we show that venoms produced by extant predatory assassin bugs have strong anticoagulant properties mediated chiefly by proteolytic degradation of fibrinogen, and additionally contain anticoagulant disulfide-rich peptides.

Phylogeny, envenomation syndrome, and membrane permeabilising venom produced by Australia's electric caterpillar Comana monomorpha.

Zygaenoidea is a superfamily of lepidopterans containing many venomous species, including the Limacodidae (nettle caterpillars) and Megalopygidae (asp caterpillars). Venom proteomes have been recently documented for several species from each of these families, but further data are required to understand the evolution of venom in Zygaenoidea. In this study, we examined the 'electric' caterpillar from North-Eastern Australia, a limacodid caterpillar densely covered in venomous spines.

Structural analysis of a U-superfamily conotoxin containing a mini-granulin fold: Insights into key features that distinguish between the ICK and granulin folds.

We are entering an exciting time in structural biology where artificial intelligence can be used to predict protein structures with greater accuracy than ever before. Extending this level of accuracy to the predictions of disulfide-rich peptide structures is likely to be more challenging, at least in the short term, given the tight packing of cysteine residues and the numerous ways that the disulfide bonds can potentially be linked. It has been previously shown in many cases that several disulfide bond connectivities can be accommodated by a single set of NMR-derived structural data without significant violations.

Peptide toxins that target vertebrate voltage-gated sodium channels underly the painful stings of harvester ants.

Harvester ants (genus Pogonomyrmex) are renowned for their stings which cause intense, long-lasting pain, and other neurotoxic symptoms in vertebrates. Here, we show that harvester ant venoms are relatively simple and composed largely of peptide toxins. One class of peptides is primarily responsible for the long-lasting local pain of envenomation via activation of peripheral sensory neurons.

Identification of sodium channel toxins from marine cone snails of the subgenera Textilia and Afonsoconus.

Voltage-gated sodium (Na) channels are transmembrane proteins that play a critical role in electrical signaling in the nervous system and other excitable tissues. µ-Conotoxins are peptide toxins from the venoms of marine cone snails (genus Conus) that block Na channels with nanomolar potency. Most species of the subgenera Textilia and Afonsoconus are difficult to acquire; therefore, their venoms have yet to be comprehensively interrogated for µ-conotoxins.

Ant venoms contain vertebrate-selective pain-causing sodium channel toxins.

Stings of certain ant species (Hymenoptera: Formicidae) can cause intense, long-lasting nociception. Here we show that the major contributors to these symptoms are venom peptides that modulate the activity of voltage-gated sodium (Na) channels, reducing their voltage threshold for activation and inhibiting channel inactivation. These peptide toxins are likely vertebrate-selective, consistent with a primarily defensive function.

Pain-causing stinging nettle toxins target TMEM233 to modulate Na1.7 function.

Voltage-gated sodium (Na) channels are critical regulators of neuronal excitability and are targeted by many toxins that directly interact with the pore-forming α subunit, typically via extracellular loops of the voltage-sensing domains, or residues forming part of the pore domain. Excelsatoxin A (ExTxA), a pain-causing knottin peptide from the Australian stinging tree Dendrocnide excelsa, is the first reported plant-derived Na channel modulating peptide toxin. Here we show that TMEM233, a member of the dispanin family of transmembrane proteins expressed in sensory neurons, is essential for pharmacological activity of ExTxA at Na channels, and that co-expression of TMEM233 modulates the gating properties of Na1.

Characterisation of Elevenin-Vc1 from the Venom of : A Structural Analogue of α-Conotoxins.

Elevenins are peptides found in a range of organisms, including arthropods, annelids, nematodes, and molluscs. They consist of 17 to 19 amino acid residues with a single conserved disulfide bond. The subject of this study, elevenin-Vc1, was first identified in the venom of the cone snail ( , , 11-18).

Intra-colony venom diversity contributes to maintaining eusociality in a cooperatively breeding ant.

Background: Eusociality is widely considered to evolve through kin selection, where the reproductive success of an individual's close relative is favored at the expense of its own. High genetic relatedness is thus considered a prerequisite for eusociality. While ants are textbook examples of eusocial animals, not all ants form colonies of closely related individuals.

Venom composition and pain-causing toxins of the Australian great carpenter bee Xylocopa aruana.

Most species of bee are capable of delivering a defensive sting which is often painful. A solitary lifestyle is the ancestral state of bees and most extant species are solitary, but information on bee venoms comes predominantly from studies on eusocial species. In this study we investigated the venom composition of the Australian great carpenter bee, Xylocopa aruana Ritsema, 1876.

Neurotoxic and cytotoxic peptides underlie the painful stings of the tree nettle Urtica ferox.

The stinging hairs of plants from the family Urticaceae inject compounds that inflict pain to deter herbivores. The sting of the New Zealand tree nettle (Urtica ferox) is among the most painful of these and can cause systemic symptoms that can even be life-threatening; however, the molecular species effecting this response have not been elucidated. Here we reveal that two classes of peptide toxin are responsible for the symptoms of U.

Physiological constraints dictate toxin spatial heterogeneity in snake venom glands.

Background: Venoms are ecological innovations that have evolved numerous times, on each occasion accompanied by the co-evolution of specialised morphological and behavioural characters for venom production and delivery. The close evolutionary interdependence between these characters is exemplified by animals that control the composition of their secreted venom. This ability depends in part on the production of different toxins in different locations of the venom gland, which was recently documented in venomous snakes.

Proteotranscriptomics reveals the secretory dynamics of teratocytes, regulators of parasitization by an endoparasitoid wasp.

Parasitoid wasps have evolved sophisticated mechanisms of host regulation that establish a favorable environment for the development of immature parasitoids. While maternal venom and symbiotic virus-like particles are well-known mechanisms of host regulation, another less-studied mechanism is the secretion of host regulation factors by cells called teratocytes, extra-embryonic cells released during parasitoid larval eclosion. Consequently, identification and characterization of teratocyte secretory products has not been reported in detail for any parasitoid wasp.

A peptide toxin in ant venom mimics vertebrate EGF-like hormones to cause long-lasting hypersensitivity in mammals.

Venoms are excellent model systems for studying evolutionary processes associated with predator-prey interactions. Here, we present the discovery of a peptide toxin, MIITX-Mg1a, which is a major component of the venom of the Australian giant red bull ant and has evolved to mimic, both structurally and functionally, vertebrate epidermal growth factor (EGF) peptide hormones. We show that Mg1a is a potent agonist of the mammalian EGF receptor ErbB1, and that intraplantar injection in mice causes long-lasting hypersensitivity of the injected paw.

A pain-causing and paralytic ant venom glycopeptide.

Ants (Hymenoptera: Formicidae) are familiar inhabitants of most terrestrial environments. Although we are aware of the ability of many species to sting, knowledge of ant venom chemistry remains limited. Herein, we describe the discovery and characterization of an -linked glycopeptide (Mg7a) as a major component of the venom of the ant .

Venom composition of the endoparasitoid wasp Cotesia flavipes (Hymenoptera: Braconidae) and functional characterization of a major venom peptide.

Endoparasitoid wasps use complex biochemical arsenals to suppress the normal humoral and cellular immune responses of their hosts in order to transform them into a suitable environment for development of their eggs and larvae. Venom injected during oviposition is a key component of this arsenal, but the functions of individual venom toxins are still poorly understood. Furthermore, there has been little investigation of the potential biotechnological use of these venom toxins, for example for control of agricultural pests.