Cone snail venoms provide a largely untapped source of novel peptide drug leads. To enhance the discovery phase, a detailed comparative proteomic analysis was undertaken on milked venom from the mollusk-hunting cone snail, Conus textile, from three different geographic locations (Hawai'i, American Samoa and Australia's Great Barrier Reef). A novel milked venom conopeptide rich in post-translational modifications was discovered, characterized and named α-conotoxin TxIC. We assign this conopeptide to the 4/7 α-conotoxin family based on the peptide's sequence homology and cDNA pre-propeptide alignment. Pharmacologically, α-conotoxin TxIC demonstrates minimal activity on human acetylcholine receptor models (100 μM, <5% inhibition), compared to its high paralytic potency in invertebrates, PD50 = 34.2 nMol Kg-1. The non-post-translationally modified form, [Pro]2,8[Glu]16α-conotoxin TxIC, demonstrates differential selectivity for the α3β2 isoform of the nicotinic acetylcholine receptor with maximal inhibition of 96% and an observed IC50 of 5.4 ± 0.5 μM. Interestingly its comparative PD50 (3.6 μMol Kg-1) in invertebrates was ∼100 fold more than that of the native peptide. Differentiating α-conotoxin TxIC from other α-conotoxins is the high degree of post-translational modification (44% of residues). This includes the incorporation of γ-carboxyglutamic acid, two moieties of 4-trans hydroxyproline, two disulfide bond linkages, and C-terminal amidation. These findings expand upon the known chemical diversity of α-conotoxins and illustrate a potential driver of toxin phyla-selectivity within Conus.

Blackwater diving,'' or nighttime SCUBA diving in epipelagic environments, has become highly popular in recent years because lay participants encounter animals that are difficult and expensive to observe through other methods. These same observations can be priceless for researchers working with these species, so an interface between the scientific communities and recreational divers would be mutually beneficial. In this paper, we describe one such interface through the photography, collection, and DNA barcoding of larval fishes from the island of Hawaii. The images and videos from this activity provide an exciting window into the epipelagic environment and the way larval fishes appear and swim within it. Blackwater diving allows us to see the often-elaborate appendages and other specializations of these larvae as they appear in situ, prior to extensive net and fixation damage. However, blackwater diving remains an almost exclusively recreational pursuit, particularly popular among underwater photographers, who have little interest in (or object to) collecting specimens for scientists. Nonetheless, a logical next step is careful hand collection of specimens for scientific study. Growing numbers of recreational divers around the world have access to an otherwise expensive-to-research habitat. Here we present, for the first time, in situ and post-fixation photos of larval fishes that were hand collected and fixed in 95% ethanol by blackwater divers operating out of Kona, Hawaii, with DNA barcode identifications congruent with morphology and pigmentation where possible. With the right motivation, blackwater diving could augment research in the pelagic ocean and significantly enhance natural history collections and our knowledge of the larvae of marine fishes.

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