Posted by Stephanie A. Smith, Ph.D., on Thu, March 12, 2015
In eager anticipation of March Madness, I figured now would be a good time for the next installment of the HAB Five. Nodularin is a close cousin of microcystin, and is also toxic to the liver. Nodularin is a cyclic pentapeptide, while microcystin is a cyclic heptapeptide. There are 7 naturally-occurring forms of nodularin, and two of them are actually not even toxic. While the limited studies available suggest that nodularin is as potent or more potent than microcystins, it has received not nearly as much study over the years. Enough has gone on to yield the following 5 interesting facts, though:
- Unlike microcystin, which appears to be produced by a number (maybe as many as 8) of genera of cyanobacteria, nodularin is pretty much mainly found in the genus Nodularia, and organisms of that genus are mainly found in brackish water.
Nodularia spumigena was the first cyanobacterium to be officially reported to cause animal poisonings. The title of the report in an 1878 issue of the still-popular journal Nature was telling: “Poisonous Australian lake.” (Francis, G. 1878. Nature 18:11)
- One of the largest algae blooms ever recorded was primarily due to Nodularia, and it was in the Baltic Sea in July 2010, and it covered 377,000 km2 in size (approximately the size of Germany).
- Structurally nodularin is so similar to microcystin that the most popular tool for measuring the microcystins, the ADDA kit from Abraxis, cannot distinguish between them.
- There’s an oddball out there called motuporin, which was isolated from a marine sponge in Papau New Guinea (deSilva et al., Tetrahedron Lett. 1992 33:1561). Structurally, it is a nodularin (sometimes it’s called Nodularin-V). But who makes it…the sponge or a symbiotic cyanobacterium?
Next month, when I will likely have been crowned the winner of Beagle Bioproducts’ March Madness pool, we’ll talk about cylindrospermopsin!