Cytoskeleton-based lipid transport in a parasitic protozoan, Giardia lamblia.

Abstract

The early-divergent protozoan Giardia lamblia, which is a major cause of waterborne enteric disease worldwide, was shown to possess limited lipid synthesis ability and to depend upon preformed lipid molecules for energy production and membrane biosynthesis. Therefore, questions regarding how Giardia imports and utilizes exogenous lipids are important. Using fluorescent lipids and fatty acids as reporter molecules, we show that anti-actin and anti-microtubule agents affect the uptake, intracellular movement and recycling of fluorescent lipids in Giardia, which indicates that lipid transport in this protozoan parasite, as in higher eukaryotes, is dependent upon cytoskeleton filaments. We propose that actin/microtubule-based lipid and vesicular transport, which is operative in Giardia, could be an ancient cellular process that most probably evolved before the emergence of the mitochondrion and other characteristic eukaryotic organelles.