Sea anemones use an arsenal of peptide neurotoxins accumulated in special stinging cells (nematocytes) for defense and predation. Intriguingly, genomic analysis of Nematostella vectensis revealed only a single toxin, Nv1 (N. vectensis toxin 1), encoded by multiple extremely conserved genes. We examined the toxic potential of Nv1 and whether it is produced by the three developmental stages (embryo, planula, and polyp) of Nematostella. Nv1 was expressed in recombinant form and, similarly to Type I sea anemone toxins, inhibited the inactivation of voltage-gated sodium channels. However, in contrast to the other toxins, Nv1 revealed high specificity for insect over mammalian voltage-gated sodium channels. Transcript analysis indicated that multiple Nv1 loci are transcribed at all developmental stages of N. vectensis, whereas splicing of these transcripts is restricted to the polyp stage. This finding suggests that regulation of Nv1 synthesis is posttranscriptional and that the embryo and planula stages do not produce the Nv1 toxin. This rare phenomenon of intron retention at the early developmental stages is intriguing and raises the question as to the mechanism enabling such differential expression in sea anemones.
Bibliographical noteFunding Information:
This article is dedicated to the memory of Prof. Andre Menez. M.G. and D.G. were supported by United States–Israel Binational Agricultural Research and Development Grants IS-3928-06 and IS-4066-07 and by Israeli Science Foundation Grant 909/04. J.R.F. was supported by Environmental Protection Agency Grant F5E11155 (together with A.M.R.) and National Science Foundation Grant FP-91656101-0 (together with J.C.S.). A.M.R. was supported by a Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by The Beacon Institute for Rivers and Estuaries and the J. Seward Johnson Fund.
- Nematostella vectensis
- intron retention
- recombinant expression
- sea anemone toxins