First purported images of ciguatoxin-3C by cryogenic and transmission electron microscopy

Abstract

Marine biotoxins in seafood products are responsible for human illnesses and seafood production losses. Ciguatera poisoning (CP) is the most commonly reported non-bacterial seafood-related illness worldwide and is caused by the consumption of fish or shellfish containing ciguatoxins (CTXs), a class of polycyclic polyether marine biotoxins with highly complex chemical structures. Reliable laboratory testing in clinical samples for CTXs is not available and many analogues remain structurally unresolved. CTXs have a proposed backbone size of 3 nm but have never been directly observed. Herein, the first purported images of CTX-3C obtained by Cryogenic Electron Microscopy (Cryo-EM) and in the presence of gold nanoparticles with attached antibodies by Transmission Electron Microscopy (TEM) are presented. TEM image was captured based on a sample preparation optimization technique using anti-ciguatoxins CTX-3C [1C49] Ab00350–1.1 purified antibodies, gold nanoparticles, and a concentration of synthetic CTX-3C molecules combined for imaging. We discuss how other existing instrumentations with atomic resolutions exceeding <0.1 nm could be applied using this preparatory method to observe, with greater detail, the common backbone of all known CTXs and its proposed wider adoption towards other marine biotoxins. Conventional detection methods for marine toxins have drawbacks, applying cutting-edge existing technologies such as TEMs to directly observe never-before-seen marine toxins can contribute to the fundamental science of marine toxins research.