scholarly journals Venom duct origins of prey capture and defensive conotoxins in piscivorous Conus striatus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. W. A. Himaya ◽  
Ai-Hua Jin ◽  
Brett Hamilton ◽  
Subash K. Rai ◽  
Paul Alewood ◽  
...  
Keyword(s):  
Adaptive Evolution ◽  
Prey Capture ◽  
High Abundance ◽  
Dietary Shift ◽  
Species Radiation ◽  
Cone Snails ◽  
Conus Striatus

AbstractThe venom duct origins of predatory and defensive venoms has not been studied for hook-and-line fish hunting cone snails despite the pharmacological importance of their venoms. To better understand the biochemistry and evolution of injected predatory and defensive venoms, we compared distal, central and proximal venom duct sections across three specimens of C. striatus (Pionoconus) using proteomic and transcriptomic approaches. A total of 370 conotoxin precursors were identified from the whole venom duct transcriptome. Milked defensive venom was enriched with a potent cocktail of proximally expressed inhibitory α-, ω- and μ-conotoxins compared to milked predatory venom. In contrast, excitatory κA-conotoxins dominated both the predatory and defensive venoms despite their distal expression, suggesting this class of conotoxin can be selectively expressed from the same duct segment in response to either a predatory or defensive stimuli. Given the high abundance of κA-conotoxins in the Pionoconus clade, we hypothesise that the κA-conotoxins have evolved through adaptive evolution following their repurposing from ancestral inhibitory A superfamily conotoxins to facilitate the dietary shift to fish hunting and species radiation in this clade.

scholarly journals The α1-adrenoceptor inhibitor ρ-TIA facilitates net hunting in piscivorous Conus tulipa

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mriga Dutt ◽  
Jean Giacomotto ◽  
Lotten Ragnarsson ◽  
Åsa Andersson ◽  
Andreas Brust ◽  
...  
Keyword(s):  
Escape Response ◽  
Prey Capture ◽  
Active Components ◽  
Defensive Strategies ◽  
Adrenoceptor Antagonist ◽  
Low Concentrations ◽  
Aquarium Water ◽  
Cone Snails ◽  
Behaviour Models ◽  
Receptor Agonists And Antagonists

AbstractCone snails use separately evolved venoms for prey capture and defence. While most use a harpoon for prey capture, the Gastridium clade that includes the well-studied Conus geographus and Conus tulipa, have developed a net hunting strategy to catch fish. This unique feeding behaviour requires secretion of “nirvana cabal” peptides to dampen the escape response of targeted fish allowing for their capture directly by mouth. However, the active components of the nirvana cabal remain poorly defined. In this study, we evaluated the behavioural effects of likely nirvana cabal peptides on the teleost model, Danio rerio (zebrafish). Surprisingly, the conantokins (NMDA receptor antagonists) and/or conopressins (vasopressin receptor agonists and antagonists) found in C. geographus and C. tulipa venom failed to produce a nirvana cabal-like effect in zebrafish. In contrast, low concentrations of the non-competitive adrenoceptor antagonist ρ-TIA found in C. tulipa venom (EC50 = 190 nM) dramatically reduced the escape response of zebrafish larvae when added directly to aquarium water. ρ-TIA inhibited the zebrafish α1-adrenoceptor, confirming ρ-TIA has the potential to reverse the known stimulating effects of norepinephrine on fish behaviour. ρ-TIA may act alone and not as part of a cabal, since it did not synergise with conopressins and/or conantokins. This study highlights the importance of using ecologically relevant animal behaviour models to decipher the complex neurobiology underlying the prey capture and defensive strategies of cone snails.

scholarly journals Prey-Capture Strategies of Fish-Hunting Cone Snails: Behavior, Neurobiology and Evolution

2015 ◽  
Vol 86 (1) ◽  
pp. 58-74 ◽  
Author(s):  
Baldomero M. Olivera ◽  
Jon Seger ◽  
Martin P. Horvath ◽  
Alexander E. Fedosov
Keyword(s):  
Phylogenetic Trees ◽  
Prey Capture ◽  
Food Resource ◽  
Hunting Behavior ◽  
Molecular Features ◽  
Extant Species ◽  
Biochemical Components ◽  
Cone Snails ◽  
Physical Features ◽  
Radular Tooth

The venomous fish-hunting cone snails (Conus) comprise eight distinct lineages evolved from ancestors that preyed on worms. In this article, we attempt to reconstruct events resulting in this shift in food resource by closely examining patterns of behavior, biochemical agents (toxins) that facilitate prey capture and the combinations of toxins present in extant species. The first sections introduce three different hunting behaviors associated with piscivory: ‘taser-and-tether', ‘net-engulfment' and ‘strike-and-stalk'. The first two fish-hunting behaviors are clearly associated with distinct groups of venom components, called cabals, which act in concert to modify the behavior of prey in a specific manner. Derived fish-hunting behavior clearly also correlates with physical features of the radular tooth, the device that injects these biochemical components. Mapping behavior, biochemical components and radular tooth features onto phylogenetic trees shows that fish-hunting behavior emerged at least twice during evolution. The system presented here may be one of the best examples where diversity in structure, physiology and molecular features were initially driven by particular pathways selected through behavior.

scholarly journals Specialized insulin is used for chemical warfare by fish-hunting cone snails

2015 ◽  
Vol 112 (6) ◽  
pp. 1743-1748 ◽  
Author(s):  
Helena Safavi-Hemami ◽  
Joanna Gajewiak ◽  
Santhosh Karanth ◽  
Samuel D. Robinson ◽  
Beatrix Ueberheide ◽  
...  
Keyword(s):  
Nervous System ◽  
Blood Glucose ◽  
Energy Metabolism ◽  
Ion Channels ◽  
Posttranslational Modifications ◽  
Prey Capture ◽  
Chemical Warfare ◽  
Small Fish ◽  
Venom Component ◽  
Cone Snails

More than 100 species of venomous cone snails (genus Conus) are highly effective predators of fish. The vast majority of venom components identified and functionally characterized to date are neurotoxins specifically targeted to receptors, ion channels, and transporters in the nervous system of prey, predators, or competitors. Here we describe a venom component targeting energy metabolism, a radically different mechanism. Two fish-hunting cone snails, Conus geographus and Conus tulipa, have evolved specialized insulins that are expressed as major components of their venoms. These insulins are distinctive in having much greater similarity to fish insulins than to the molluscan hormone and are unique in that posttranslational modifications characteristic of conotoxins (hydroxyproline, γ-carboxyglutamate) are present. When injected into fish, the venom insulin elicits hypoglycemic shock, a condition characterized by dangerously low blood glucose. Our evidence suggests that insulin is specifically used as a weapon for prey capture by a subset of fish-hunting cone snails that use a net strategy to capture prey. Insulin appears to be a component of the nirvana cabal, a toxin combination in these venoms that is released into the water to disorient schools of small fish, making them easier to engulf with the snail’s distended false mouth, which functions as a net. If an entire school of fish simultaneously experiences hypoglycemic shock, this should directly facilitate capture by the predatory snail.

Pharmacology of predatory and defensive venom peptides in cone snails

2017 ◽  
Vol 13 (12) ◽  
pp. 2453-2465 ◽  
Author(s):  
Jutty Rajan Prashanth ◽  
Sebastien Dutertre ◽  
Richard James Lewis
Keyword(s):  
Prey Capture ◽  
Venom Peptides ◽  
Venom Evolution ◽  
Cone Snails ◽  
Potential Therapeutics

Cone snails use distinct venoms for defence and prey capture. The pharmacology of these neurotoxic peptides have been extensively studied for pharmacological probes, venom evolution mechanisms and potential therapeutics.

scholarly journals Non-Peptidic Small Molecule Components from Cone Snail Venoms

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhenjian Lin ◽  
Joshua P. Torres ◽  
Maren Watkins ◽  
Noemi Paguigan ◽  
Changshan Niu ◽  
...  
Keyword(s):  
Small Molecules ◽  
Small Molecule ◽  
Prey Capture ◽  
Marine Biodiversity ◽  
Cone Snail ◽  
Pharmacological Agents ◽  
Basal Clade ◽  
Initial Discovery ◽  
Cone Snails ◽  
Pharmaceutical Agents

Venomous molluscs (Superfamily Conoidea) comprise a substantial fraction of tropical marine biodiversity (>15,000 species). Prior characterization of cone snail venoms established that bioactive venom components used to capture prey, defend against predators and for competitive interactions were relatively small, structured peptides (10–35 amino acids), most with multiple disulfide crosslinks. These venom components (“conotoxins, conopeptides”) have been widely studied in many laboratories, leading to pharmaceutical agents and probes. In this review, we describe how it has recently become clear that to varying degrees, cone snail venoms also contain bioactive non-peptidic small molecule components. Since the initial discovery of genuanine as the first bioactive venom small molecule with an unprecedented structure, a broad set of cone snail venoms have been examined for non-peptidic bioactive components. In particular, a basal clade of cone snails (Stephanoconus) that prey on polychaetes produce genuanine and many other small molecules in their venoms, suggesting that this lineage may be a rich source of non-peptidic cone snail venom natural products. In contrast to standing dogma in the field that peptide and proteins are predominantly used for prey capture in cone snails, these small molecules also contribute to prey capture and push the molecular diversity of cone snails beyond peptides. The compounds so far characterized are active on neurons and thus may potentially serve as leads for neuronal diseases. Thus, in analogy to the incredible pharmacopeia resulting from studying venom peptides, these small molecules may provide a new resource of pharmacological agents.

Omnivorous diet of the endangered Pygmy Bluetongue Lizard, Tiliqua adelaidensis

2007 ◽  
Vol 28 (4) ◽  
pp. 560-565 ◽  
Author(s):  
Michael Bull ◽  
Mark Hutchinson ◽  
Aaron Fenner
Keyword(s):  
Plant Material ◽  
Prey Capture ◽  
South Australia ◽  
High Abundance ◽  
Diet Change ◽  
Omnivorous Diet

Abstract We used scats from 71 individuals to determine the diet of the endangered Pygmy Bluetongue Lizard, Tiliqua adelaidensis, from South Australia. As predicted both from its previously reported behaviour as an ambush forager, and from its relatively small size, this scincid lizard feeds largely on arthropod prey, and the prey in the diet change opportunistically over the spring and summer. As expected, the species is less herbivorous than larger species in the same or related genera. However plant material is included in the diet to a greater extent as the summer progresses. Conservation of this species may rely on maintaining a high abundance of arthropod prey, and a habitat where efficient prey capture is possible, and on retaining appropriate plants in the species' habitat.

scholarly journals Insights into the origins of fish hunting in venomous cone snails from studies of Conus tessulatus

2015 ◽  
Vol 112 (16) ◽  
pp. 5087-5092 ◽  
Author(s):  
Joseph W. Aman ◽  
Julita S. Imperial ◽  
Beatrix Ueberheide ◽  
Min-Min Zhang ◽  
Manuel Aguilar ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Prey Capture ◽  
Sequence Similarity ◽  
Cone Snail ◽  
Evolutionary Transitions ◽  
Voltage Gated ◽  
Channel Inactivation ◽  
Voltage Gated Sodium Channels ◽  
Cone Snails

Prey shifts in carnivorous predators are events that can initiate the accelerated generation of new biodiversity. However, it is seldom possible to reconstruct how the change in prey preference occurred. Here we describe an evolutionary “smoking gun” that illuminates the transition from worm hunting to fish hunting among marine cone snails, resulting in the adaptive radiation of fish-hunting lineages comprising ∼100 piscivorous Conus species. This smoking gun is δ-conotoxin TsVIA, a peptide from the venom of Conus tessulatus that delays inactivation of vertebrate voltage-gated sodium channels. C. tessulatus is a species in a worm-hunting clade, which is phylogenetically closely related to the fish-hunting cone snail specialists. The discovery of a δ-conotoxin that potently acts on vertebrate sodium channels in the venom of a worm-hunting cone snail suggests that a closely related ancestral toxin enabled the transition from worm hunting to fish hunting, as δ-conotoxins are highly conserved among fish hunters and critical to their mechanism of prey capture; this peptide, δ-conotoxin TsVIA, has striking sequence similarity to these δ-conotoxins from piscivorous cone snail venoms. Calcium-imaging studies on dissociated dorsal root ganglion (DRG) neurons revealed the peptide’s putative molecular target (voltage-gated sodium channels) and mechanism of action (inhibition of channel inactivation). The results were confirmed by electrophysiology. This work demonstrates how elucidating the specific interactions between toxins and receptors from phylogenetically well-defined lineages can uncover molecular mechanisms that underlie significant evolutionary transitions.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

KOMPOSISI JENIS DAN KELIMPAHAN IKAN DI PERAIRAN TELUK DORERI, MANOKWARI

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Maria Massora
Keyword(s):  
Fish Species ◽  
Economic Value ◽  
High Abundance ◽  
Abundance Index

<em>A study was done to search the composition and abundance of fish species in the waters of the Doreri Gulf the District of Manokwari, from September - October 2005.  The fish catchments wash about 143 specimens consist of 49 species included in 23 families.  The species of fish with a high abundance index consists of Nemipterus celebicus, Upeneus sundaicus, and Upeneus sulphureus.  Those fishes have a high economic value in the market of Manokwari</em>

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