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1.
Nat Ecol Evol ; 2024 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-39496866

RESUMEN

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. We show that this control is probably achieved by a combination of this heterogenous toxin distribution with a dual mechanism of venom secretion that involves neuromuscular innervation as well as stimulation via neurotransmitters. Our results suggest that behavioural control over venom composition may be an overlooked aspect of venom biology and provide an example of how exaptation can facilitate evolutionary innovation and novelty.

2.
BMC Biol ; 22(1): 135, 2024 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-38867210

RESUMEN

BACKGROUND: Evolution of novelty is a central theme in evolutionary biology, yet studying the origins of traits with an apparently discontinuous origin remains a major challenge. Venom systems are a well-suited model for the study of this phenomenon because they capture several aspects of novelty across multiple levels of biological complexity. However, while there is some knowledge on the evolution of individual toxins, not much is known about the evolution of venom systems as a whole. One way of shedding light on the evolution of new traits is to investigate less specialised serial homologues, i.e. repeated traits in an organism that share a developmental origin. This approach can be particularly informative in animals with repetitive body segments, such as centipedes. RESULTS: Here, we investigate morphological and biochemical aspects of the defensive telopodal glandular organs borne on the posterior legs of venomous stone centipedes (Lithobiomorpha), using a multimethod approach, including behavioural observations, comparative morphology, proteomics, comparative transcriptomics and molecular phylogenetics. We show that the anterior venom system and posterior telopodal defence system are functionally convergent serial homologues, where one (telopodal defence) represents a model for the putative early evolutionary state of the other (venom). Venom glands and telopodal glandular organs appear to have evolved from the same type of epidermal gland (four-cell recto-canal type) and while the telopodal defensive secretion shares a great degree of compositional overlap with centipede venoms in general, these similarities arose predominantly through convergent recruitment of distantly related toxin-like components. Both systems are composed of elements predisposed to functional innovation across levels of biological complexity that range from proteins to glands, demonstrating clear parallels between molecular and morphological traits in the properties that facilitate the evolution of novelty. CONCLUSIONS: The evolution of the lithobiomorph telopodal defence system provides indirect empirical support for the plausibility of the hypothesised evolutionary origin of the centipede venom system, which occurred through functional innovation and gradual specialisation of existing epidermal glands. Our results thus exemplify how continuous transformation and functional innovation can drive the apparent discontinuous emergence of novelties on higher levels of biological complexity.


Asunto(s)
Artrópodos , Animales , Artrópodos/fisiología , Venenos de Artrópodos/química , Evolución Biológica , Transcriptoma , Filogenia
3.
Mar Drugs ; 21(9)2023 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-37755094

RESUMEN

Sea anemones are known to produce a diverse array of toxins with different cysteine-rich peptide scaffolds in their venoms. The serine peptidase inhibitors, specifically Kunitz inhibitors, are an important toxin family that is believed to function as defensive peptides, as well as prevent proteolysis of other secreted anemone toxins. In this study, we isolated three serine peptidase inhibitors named Anthopleura cascaia peptide inhibitors I, II, and III (ACPI-I, ACPI-II, and ACPI-III) from the venom of the endemic Brazilian sea anemone A. cascaia. The venom was fractionated using RP-HPLC, and the inhibitory activity of these fractions against trypsin was determined and found to range from 59% to 93%. The spatial distribution of the anemone peptides throughout A. cascaia was observed using mass spectrometry imaging. The inhibitory peptides were found to be present in the tentacles, pedal disc, and mesenterial filaments. We suggest that the three inhibitors observed during this study belong to the venom Kunitz toxin family on the basis of their similarity to PI-actitoxin-aeq3a-like and the identification of amino acid residues that correspond to a serine peptidase binding site. Our findings expand our understanding of the diversity of toxins present in sea anemone venom and shed light on their potential role in protecting other venom components from proteolysis.

4.
Nat Commun ; 14(1): 2977, 2023 05 23.
Artículo en Inglés | MEDLINE | ID: mdl-37221205

RESUMEN

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 (NaV) channels, reducing their voltage threshold for activation and inhibiting channel inactivation. These peptide toxins are likely vertebrate-selective, consistent with a primarily defensive function. They emerged early in the Formicidae lineage and may have been a pivotal factor in the expansion of ants.


Asunto(s)
Venenos de Hormiga , Hormigas , Toxinas Biológicas , Animales , Dolor , Canales de Sodio , Vertebrados
5.
BMC Biol ; 21(1): 121, 2023 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-37226201

RESUMEN

BACKGROUND: The ShK toxin from Stichodactyla helianthus has established the therapeutic potential of sea anemone venom peptides, but many lineage-specific toxin families in Actiniarians remain uncharacterised. One such peptide family, sea anemone 8 (SA8), is present in all five sea anemone superfamilies. We explored the genomic arrangement and evolution of the SA8 gene family in Actinia tenebrosa and Telmatactis stephensoni, characterised the expression patterns of SA8 sequences, and examined the structure and function of SA8 from the venom of T. stephensoni. RESULTS: We identified ten SA8-family genes in two clusters and six SA8-family genes in five clusters for T. stephensoni and A. tenebrosa, respectively. Nine SA8 T. stephensoni genes were found in a single cluster, and an SA8 peptide encoded by an inverted SA8 gene from this cluster was recruited to venom. We show that SA8 genes in both species are expressed in a tissue-specific manner and the inverted SA8 gene has a unique tissue distribution. While the functional activity of the SA8 putative toxin encoded by the inverted gene was inconclusive, its tissue localisation is similar to toxins used for predator deterrence. We demonstrate that, although mature SA8 putative toxins have similar cysteine spacing to ShK, SA8 peptides are distinct from ShK peptides based on structure and disulfide connectivity. CONCLUSIONS: Our results provide the first demonstration that SA8 is a unique gene family in Actiniarians, evolving through a variety of structural changes including tandem and proximal gene duplication and an inversion event that together allowed SA8 to be recruited into the venom of T. stephensoni.


Asunto(s)
Anémonas de Mar , Animales , Anémonas de Mar/genética , Genómica , Inversión Cromosómica , Cisteína , Disulfuros
6.
Toxins (Basel) ; 15(3)2023 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-36977115

RESUMEN

Aculeate hymenopterans use their venom for a variety of different purposes. The venom of solitary aculeates paralyze and preserve prey without killing it, whereas social aculeates utilize their venom in defence of their colony. These distinct applications of venom suggest that its components and their functions are also likely to differ. This study investigates a range of solitary and social species across Aculeata. We combined electrophoretic, mass spectrometric, and transcriptomic techniques to characterize the compositions of venoms from an incredibly diverse taxon. In addition, in vitro assays shed light on their biological activities. Although there were many common components identified in the venoms of species with different social behavior, there were also significant variations in the presence and activity of enzymes such as phospholipase A2s and serine proteases and the cytotoxicity of the venoms. Social aculeate venom showed higher presence of peptides that cause damage and pain in victims. The venom-gland transcriptome from the European honeybee (Apis mellifera) contained highly conserved toxins which match those identified by previous investigations. In contrast, venoms from less-studied taxa returned limited results from our proteomic databases, suggesting that they contain unique toxins.


Asunto(s)
Himenópteros , Toxinas Biológicas , Animales , Abejas , Ponzoñas/toxicidad , Proteómica , Transcriptoma
7.
Nat Commun ; 14(1): 1036, 2023 02 23.
Artículo en Inglés | MEDLINE | ID: mdl-36823422

RESUMEN

Multivalent ligands of ion channels have proven to be both very rare and highly valuable in yielding unique insights into channel structure and pharmacology. Here, we describe a bivalent peptide from the venom of Xibalbanus tulumensis, a troglobitic arthropod from the enigmatic class Remipedia, that causes persistent calcium release by activation of ion channels involved in muscle contraction. The high-resolution solution structure of φ-Xibalbin3-Xt3a reveals a tandem repeat arrangement of inhibitor-cysteine knot (ICK) domains previously only found in spider venoms. The individual repeats of Xt3a share sequence similarity with a family of scorpion toxins that target ryanodine receptors (RyR). Single-channel electrophysiology and quantification of released Ca2+ stores within skinned muscle fibers confirm Xt3a as a bivalent RyR modulator. Our results reveal convergent evolution of RyR targeting toxins in remipede and scorpion venoms, while the tandem-ICK repeat architecture is an evolutionary innovation that is convergent with toxins from spider venoms.


Asunto(s)
Canal Liberador de Calcio Receptor de Rianodina , Venenos de Escorpión , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Calcio/metabolismo , Rianodina/farmacología , Secuencia de Aminoácidos , Péptidos/química , Venenos de Escorpión/farmacología , Venenos de Escorpión/química
8.
Protein Sci ; 32(2): e4566, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36644825

RESUMEN

Receptor avidity through multivalency is a highly sought-after property of ligands. While readily available in nature in the form of bivalent antibodies, this property remains challenging to engineer in synthetic molecules. The discovery of several bivalent venom peptides containing two homologous and independently folded domains (in a tandem repeat arrangement) has provided a unique opportunity to better understand the underpinning design of multivalency in multimeric biomolecules, as well as how naturally occurring multivalent ligands can be identified. In previous work, we classified these molecules as a larger class termed secreted cysteine-rich repeat-proteins (SCREPs). Here, we present an online resource; ScrepYard, designed to assist researchers in identification of SCREP sequences of interest and to aid in characterizing this emerging class of biomolecules. Analysis of sequences within the ScrepYard reveals that two-domain tandem repeats constitute the most abundant SCREP domain architecture, while the interdomain "linker" regions connecting the functional domains are found to be abundant in amino acids with short or polar sidechains and contain an unusually high abundance of proline residues. Finally, we demonstrate the utility of ScrepYard as a virtual screening tool for discovery of putatively multivalent peptides, by using it as a resource to identify a previously uncharacterized serine protease inhibitor and confirm its predicted activity using an enzyme assay.


Asunto(s)
Disulfuros , Péptidos , Secuencia de Aminoácidos , Péptidos/química , Secuencias Repetidas en Tándem , Aminoácidos
9.
BMC Biol ; 21(1): 5, 2023 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-36617555

RESUMEN

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. One such example is the ectatommine ant Rhytidoponera metallica, which predominantly forms queen-less colonies that have such a low intra-colony relatedness that they have been proposed to represent a transient, unstable form of eusociality. However, R. metallica is among the most abundant and widespread ants on the Australian continent. This apparent contradiction provides an example of how inclusive fitness may not by itself explain the maintenance of eusociality and raises the question of what other selective advantages maintain the eusocial lifestyle of this species. RESULTS: We provide a comprehensive portrait of the venom of R. metallica and show that the colony-wide venom consists of an exceptionally high diversity of functionally distinct toxins for an ant. These toxins have evolved under strong positive selection, which is normally expected to reduce genetic variance. Yet, R. metallica exhibits remarkable intra-colony variation, with workers sharing only a relatively small proportion of toxins in their venoms. This variation is not due to the presence of chemical castes, but has a genetic foundation that is at least in part explained by toxin allelic diversity. CONCLUSIONS: Taken together, our results suggest that the toxin diversity contained in R. metallica colonies may be maintained by a form of group selection that selects for colonies that can exploit more resources and defend against a wider range of predators. We propose that increased intra-colony genetic variance resulting from low kinship may itself provide a selective advantage in the form of an expanded pharmacological venom repertoire. These findings provide an example of how group selection on adaptive phenotypes may contribute to maintaining eusociality where a prerequisite for kin selection is diminished.


Asunto(s)
Hormigas , Animales , Hormigas/genética , Ponzoñas , Australia , Reproducción , Conducta Social
10.
BMC Biol ; 20(1): 148, 2022 06 27.
Artículo en Inglés | MEDLINE | ID: mdl-35761243

RESUMEN

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. Here, we test the hypothesis that the distinct spatial distributions of toxins in snake venom glands are an adaptation that enables the secretion of venoms with distinct ecological functions. RESULTS: We show that the main defensive and predatory peptide toxins are produced in distinct regions of the venom glands of the black-necked spitting cobra (Naja nigricollis), but these distributions likely reflect developmental effects. Indeed, we detected no significant differences in venom collected via defensive 'spitting' or predatory 'biting' events from the same specimens representing multiple lineages of spitting cobra. We also found the same spatial distribution of toxins in a non-spitting cobra and show that heterogeneous toxin distribution is a feature shared with a viper with primarily predatory venom. CONCLUSIONS: Our findings suggest that heterogeneous distributions of toxins are not an adaptation to controlling venom composition in snakes. Instead, it likely reflects physiological constraints on toxin production by the venom glands, opening avenues for future research on the mechanisms of functional differentiation of populations of protein-secreting cells within adaptive contexts.


Asunto(s)
Venenos de Serpiente , Serpientes , Animales , Venenos de Serpiente/química
11.
Mol Biol Evol ; 39(5)2022 05 03.
Artículo en Inglés | MEDLINE | ID: mdl-35512366

RESUMEN

Ribbon worms are active predators that use an eversible proboscis to inject venom into their prey and defend themselves with toxic epidermal secretions. Previous work on nemertean venom has largely focused on just a few species and has not investigated the different predatory and defensive secretions in detail. Consequently, our understanding of the composition and evolution of ribbon worm venoms is still very limited. Here, we present a comparative study of nemertean venom combining RNA-seq differential gene expression analyses of venom-producing tissues, tandem mass spectrometry-based proteomics of toxic secretions, and mass spectrometry imaging of proboscis sections, to shed light onto the composition and evolution of predatory and defensive toxic secretions in Antarctonemertes valida. Our analyses reveal a wide diversity of putative defensive and predatory toxins with tissue-specific gene expression patterns and restricted distributions to the mucus and proboscis proteomes respectively, suggesting that ribbon worms produce distinct toxin cocktails for predation and defense. Our results also highlight the presence of numerous lineage-specific toxins, indicating that venom evolution is highly divergent across nemerteans, producing toxin cocktails that might be finely tuned to subdue different prey. Our data also suggest that the hoplonemertean proboscis is a highly specialized predatory organ that seems to be involved in a variety of biological functions besides predation, including secretion and sensory perception. Overall, our results advance our knowledge into the diversity and evolution of nemertean venoms and highlight the importance of combining different types of data to characterize toxin composition in understudied venomous organisms.


Asunto(s)
Conducta Predatoria , Proteoma , Animales , Proteómica , Ponzoñas/genética
12.
Gigascience ; 112022 05 18.
Artículo en Inglés | MEDLINE | ID: mdl-35640874

RESUMEN

Venoms have evolved >100 times in all major animal groups, and their components, known as toxins, have been fine-tuned over millions of years into highly effective biochemical weapons. There are many outstanding questions on the evolution of toxin arsenals, such as how venom genes originate, how venom contributes to the fitness of venomous species, and which modifications at the genomic, transcriptomic, and protein level drive their evolution. These questions have received particularly little attention outside of snakes, cone snails, spiders, and scorpions. Venom compounds have further become a source of inspiration for translational research using their diverse bioactivities for various applications. We highlight here recent advances and new strategies in modern venomics and discuss how recent technological innovations and multi-omic methods dramatically improve research on venomous animals. The study of genomes and their modifications through CRISPR and knockdown technologies will increase our understanding of how toxins evolve and which functions they have in the different ontogenetic stages during the development of venomous animals. Mass spectrometry imaging combined with spatial transcriptomics, in situ hybridization techniques, and modern computer tomography gives us further insights into the spatial distribution of toxins in the venom system and the function of the venom apparatus. All these evolutionary and biological insights contribute to more efficiently identify venom compounds, which can then be synthesized or produced in adapted expression systems to test their bioactivity. Finally, we critically discuss recent agrochemical, pharmaceutical, therapeutic, and diagnostic (so-called translational) aspects of venoms from which humans benefit.


Asunto(s)
Proteómica , Ponzoñas , Animales , Investigación , Serpientes/genética , Transcriptoma , Ponzoñas/química , Ponzoñas/genética
13.
Proc Natl Acad Sci U S A ; 119(7)2022 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-35131940

RESUMEN

Venoms are excellent model systems for studying evolutionary processes associated with predator-prey interactions. Here, we present the discovery of a peptide toxin, MIITX2-Mg1a, which is a major component of the venom of the Australian giant red bull ant Myrmecia gulosa 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. These data reveal a previously undescribed venom mode of action, highlight a role for ErbB receptors in mammalian pain signaling, and provide an example of molecular mimicry driven by defensive selection pressure.


Asunto(s)
Venenos de Hormiga/química , Hormigas/fisiología , Hipersensibilidad a las Drogas , Factor de Crecimiento Epidérmico/química , Toxinas Biológicas/química , Secuencia de Aminoácidos , Animales , Mordeduras y Picaduras de Insectos , Ratones , Imitación Molecular
14.
Mar Drugs ; 20(2)2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-35200669

RESUMEN

(1) Background: G protein-coupled inward-rectifier potassium (GIRK) channels, especially neuronal GIRK1/2 channels, have been the focus of intense research interest for developing drugs against brain diseases. In this context, venom peptides that selectively activate GIRK channels can be seen as a new source for drug development. Here, we report on the identification and electrophysiological characterization of a novel activator of GIRK1/2 channels, AsKC11, found in the venom of the sea anemone Anemonia sulcata. (2) Methods: AsKC11 was purified from the sea anemone venom by reverse-phase chromatography and the sequence was identified by mass spectrometry. Using the two-electrode voltage-clamp technique, the activity of AsKC11 on GIRK1/2 channels was studied and its selectivity for other potassium channels was investigated. (3) Results: AsKC11, a Kunitz peptide found in the venom of A. sulcata, is the first peptide shown to directly activate neuronal GIRK1/2 channels independent from Gi/o protein activity, without affecting the inward-rectifier potassium channel (IRK1) and with only a minor effect on KV1.6 channels. Thus, AsKC11 is a novel activator of GIRK channels resulting in larger K+ currents because of an increased chord conductance. (4) Conclusions: These discoveries provide new insights into a novel class of GIRK activators.


Asunto(s)
Venenos de Cnidarios/química , Canales de Potasio Rectificados Internamente Asociados a la Proteína G/efectos de los fármacos , Péptidos/farmacología , Animales , Cromatografía de Fase Inversa , Femenino , Canales de Potasio Rectificados Internamente Asociados a la Proteína G/metabolismo , Espectrometría de Masas , Técnicas de Placa-Clamp , Péptidos/química , Péptidos/aislamiento & purificación , Xenopus laevis
15.
Proc Natl Acad Sci U S A ; 119(5)2022 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-35074873

RESUMEN

The King Baboon spider, Pelinobius muticus, is a burrowing African tarantula. Its impressive size and appealing coloration are tempered by reports describing severe localized pain, swelling, itchiness, and muscle cramping after accidental envenomation. Hyperalgesia is the most prominent symptom after bites from P. muticus, but the molecular basis by which the venom induces pain is unknown. Proteotranscriptomic analysis of P. muticus venom uncovered a cysteine-rich peptide, δ/κ-theraphotoxin-Pm1a (δ/κ-TRTX-Pm1a), that elicited nocifensive behavior when injected into mice. In small dorsal root ganglion neurons, synthetic δ/κ-TRTX-Pm1a (sPm1a) induced hyperexcitability by enhancing tetrodotoxin-resistant sodium currents, impairing repolarization and lowering the threshold of action potential firing, consistent with the severe pain associated with envenomation. The molecular mechanism of nociceptor sensitization by sPm1a involves multimodal actions over several ion channel targets, including NaV1.8, KV2.1, and tetrodotoxin-sensitive NaV channels. The promiscuous targeting of peptides like δ/κ-TRTX-Pm1a may be an evolutionary adaptation in pain-inducing defensive venoms.


Asunto(s)
Nociceptores/efectos de los fármacos , Papio/metabolismo , Péptidos/farmacología , Venenos de Araña/farmacología , Arañas/metabolismo , Potenciales de Acción/efectos de los fármacos , Animales , Ganglios Espinales/efectos de los fármacos , Hiperalgesia/tratamiento farmacológico , Canales Iónicos/metabolismo , Ratones , Dolor/tratamiento farmacológico , Tetrodotoxina/farmacología
16.
Mol Ecol ; 31(3): 866-883, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34837433

RESUMEN

The phylum Cnidaria is the oldest extant venomous group and is defined by the presence of nematocysts, specialized organelles responsible for venom production and delivery. Although toxin peptides and the cells housing nematocysts are distributed across the entire animal, nematocyte and venom profiles have been shown to differ across morphological structures in actiniarians. In this study, we explore the relationship between patterns of toxin expression and the ecological roles of discrete anatomical structures in Telmatactis stephensoni. Specifically, using a combination of proteomic and transcriptomic approaches, we examined whether there is a direct correlation between the functional similarity of regions and the similarity of their associated toxin expression profiles. We report that the regionalization of toxin production is consistent with the partitioning of the ecological roles of venom across envenomating structures, and that three major functional regions are present in T. stephensoni: tentacles, epidermis and gastrodermis. Additionally, we find that most structures that serve similar functions not only have comparable putative toxin profiles but also similar nematocyst types. There was no overlap in the putative toxins identified using proteomics and transcriptomics, but the expression patterns of specific milked venom peptides were conserved across RNA-sequencing and mass spectrometry imaging data sets. Furthermore, based on our data, it appears that acontia of T. stephensoni may be transcriptionally inactive and only mature nematocysts are present in the distal portions of the threads. Overall, we find that the venom profile of different anatomical regions in sea anemones varies according to its ecological functions.


Asunto(s)
Venenos de Cnidarios , Anémonas de Mar , Animales , Proteómica , Anémonas de Mar/genética , Análisis de Secuencia de ARN , Transcriptoma
17.
iScience ; 24(10): 103175, 2021 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-34693225

RESUMEN

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 O-linked glycopeptide (Mg7a) as a major component of the venom of the ant Myrmecia gulosa. Electron transfer dissociation and higher-energy collisional dissociation tandem mass spectrometry were used to localize three α-N-acetylgalactosaminyl residues (α-GalNAc) present on the 63-residue peptide. To allow for functional studies, we synthesized the full-length glycosylated peptide via solid-phase peptide synthesis, combined with diselenide-selenoester ligation-deselenization chemistry. We show that Mg7a is paralytic and lethal to insects, and triggers pain behavior and inflammation in mammals, which it achieves through a membrane-targeting mode of action. Deglycosylation of Mg7a renders it insoluble in aqueous solution, suggesting a key solubilizing role of the O-glycans.

18.
Toxins (Basel) ; 13(7)2021 06 29.
Artículo en Inglés | MEDLINE | ID: mdl-34209745

RESUMEN

Phylum Cnidaria is an ancient venomous group defined by the presence of cnidae, specialised organelles that serve as venom delivery systems. The distribution of cnidae across the body plan is linked to regionalisation of venom production, with tissue-specific venom composition observed in multiple actiniarian species. In this study, we assess whether morphological variants of tentacles are associated with distinct toxin expression profiles and investigate the functional significance of specialised tentacular structures. Using five sea anemone species, we analysed differential expression of toxin-like transcripts and found that expression levels differ significantly across tentacular structures when substantial morphological variation is present. Therefore, the differential expression of toxin genes is associated with morphological variation of tentacular structures in a tissue-specific manner. Furthermore, the unique toxin profile of spherical tentacular structures in families Aliciidae and Thalassianthidae indicate that vesicles and nematospheres may function to protect branched structures that host a large number of photosynthetic symbionts. Thus, hosting zooxanthellae may account for the tentacle-specific toxin expression profiles observed in the current study. Overall, specialised tentacular structures serve unique ecological roles and, in order to fulfil their functions, they possess distinct venom cocktails.


Asunto(s)
Venenos de Cnidarios/genética , Anémonas de Mar/anatomía & histología , Anémonas de Mar/genética , Animales , Transcriptoma
19.
Toxicon X ; 9-10: 100070, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34195606

RESUMEN

Snakebite envenoming is a neglected tropical disease that may claim over 100,000 human lives annually worldwide. Snakebite occurs as the result of an interaction between a human and a snake that elicits either a defensive response from the snake or, more rarely, a feeding response as the result of mistaken identity. Snakebite envenoming is therefore a biological and, more specifically, an ecological problem. Snake venom itself is often described as a "cocktail", as it is a heterogenous mixture of molecules including the toxins (which are typically proteinaceous) responsible for the pathophysiological consequences of envenoming. The primary function of venom in snake ecology is pre-subjugation, with defensive deployment of the secretion typically considered a secondary function. The particular composition of any given venom cocktail is shaped by evolutionary forces that include phylogenetic constraints associated with the snake's lineage and adaptive responses to the snake's ecological context, including the taxa it preys upon and by which it is predated upon. In the present article, we describe how conceptual frameworks from ecology and evolutionary biology can enter into a mutually enlightening relationship with clinical toxinology by enabling the consideration of snakebite envenoming from an "ecological stance". We detail the insights that may emerge from such a perspective and highlight the ways in which the high-fidelity descriptive knowledge emerging from applications of -omics era technologies - "venomics" and "antivenomics" - can combine with evolutionary explanations to deliver a detailed understanding of this multifactorial health crisis.

20.
Biochem Pharmacol ; 192: 114693, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34302796

RESUMEN

In the face of increasing drug resistance, the development of new anthelmintics is critical for controlling nematodes that parasitise livestock. Although hymenopteran venom toxins have attracted attention for applications in agriculture and medicine, few studies have explored their potential as anthelmintics. Here we assessed hymenopteran venoms as a possible source of new anthelmintic compounds by screening a panel of ten hymenopteran venoms against Haemonchus contortus, a major pathogenic nematode of ruminants. Using bioassay-guided fractionation coupled with liquid chromatography-tandem mass spectrometry, we identified four novel anthelmintic peptides (ponericins) from the venom of the neotropical ant Neoponera commutata and the previously described ponericin M-PONTX-Na1b from Neoponera apicalis venom. These peptides inhibit H. contortus development with IC50 values of 2.8-5.6 µM. Circular dichroism spectropolarimetry indicated that the ponericins are unstructured in aqueous solution but adopt α-helical conformations in lipid mimetic environments. We show that the ponericins induce non-specific membrane perturbation, which confers broad-spectrum antimicrobial, insecticidal, cytotoxic, hemolytic, and algogenic activities, with activity across all assays typically correlated. We also show for the first time that ponericins induce spontaneous pain behaviour when injected in mice. We propose that the broad-spectrum activity of the ponericins enables them to play both a predatory and defensive role in neoponeran ants, consistent with their high abundance in venom. This study reveals a broader functionality for ponericins than previously assumed, and highlights both the opportunities and challenges in pursuing ant venom peptides as potential therapeutics.


Asunto(s)
Venenos de Hormiga/farmacología , Antihelmínticos/farmacología , Antiinfecciosos/farmacología , Hemolíticos/farmacología , Insecticidas/farmacología , Péptidos/farmacología , Secuencia de Aminoácidos , Animales , Venenos de Hormiga/genética , Venenos de Hormiga/aislamiento & purificación , Antihelmínticos/aislamiento & purificación , Antiinfecciosos/aislamiento & purificación , Hormigas , Brugia Malayi/efectos de los fármacos , Brugia Malayi/fisiología , Calliphoridae , Relación Dosis-Respuesta a Droga , Células HEK293 , Haemonchus/efectos de los fármacos , Haemonchus/fisiología , Hemolíticos/aislamiento & purificación , Humanos , Insecticidas/aislamiento & purificación , Masculino , Ratones , Ratones Endogámicos C57BL , Péptidos/genética , Péptidos/aislamiento & purificación , Ovinos
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