An examination of microcystin-LR accumulation and toxicity using tethered bilayer lipid membranes (tBLMs)

Abstract

Microcystin-LR (MC-LR) is a potent cyanobacterial toxin responsible for animal and human poisonings worldwide. MC-LR is found in organisms throughout the foodweb, however there is conjecture regarding whether it biomagnifies. Few studies have investigated how MC-LR interacts with lipid membranes, a determinant of biomagnification potential. We tested whether 1 µM MC-LR irreversibly associates with lipid bilayers or causes the creation of pore defects upon short and long-term exposure. Using tethered bilayer lipid membranes (tBLMs), we observed an increase in membrane conduction in tBLMs, representing an interaction of microcystin-LR with the lipid bilayer and a change in membrane packing properties. However, there were minimal changes in membrane capacitance upon short and long-term exposure, and MC-LR exhibited a rapid off-rate. Upon 24 h exposure to the toxin, no lipophilic multimeric complexes were detected capable of altering the toxin's off-rate. There was no evidence of the creation of new pores. This study demonstrates that MC-LR does not irreversibly imbed itself into lipids membranes after short or long-term exposure and suggests MC-LR does not biomagnify through the food web via lipid storage.

Bacterial Adherence to Plant and Animal Surfaces Via Adhesin-Lipid Interactions

“…The cyanotoxin class of hepatotoxic MC is responsible for animal and human poisoning cases due to bioaccumulation in the liver. This study demonstrated that contrary to the original hypothesis, MC-Leucine Arginine (LR) membrane exposure leads only to small and transient variations in the membrane capacitance, showing that MC-LR is not able to accumulate in cell membranes and modify their integrity (Facey et al 2019).…”

A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production

“…Cyanotoxin-containing blooms occur throughout the world and are responsible for sporadic episodes of animal illness and death, as well as human poisonings from municipal and recreational water supplies [9,10,11]. Cyanotoxins are highly variable in terms of their molecular structure, production triggers and modes of toxicity [4,11,12]. Effects range from skin irritation to cancer or even fatalities [3,13].…”