Antioxidant Role for Lipid Droplets in a Stem Cell Niche of Drosophila

SummaryStem cells reside in specialized microenvironments known as niches. During Drosophila development, glial cells provide a niche that sustains the proliferation of neural stem cells (neuroblasts) during starvation. We now find that the glial cell niche also preserves neuroblast proliferation under conditions of hypoxia and oxidative stress. Lipid droplets that form in niche glia during oxidative stress limit the levels of reactive oxygen species (ROS) and inhibit the oxidation of polyunsaturated fatty acids (PUFAs). These droplets protect glia and also neuroblasts from peroxidation chain reactions that can damage many types of macromolecules. The underlying antioxidant mechanism involves diverting PUFAs, including diet-derived linoleic acid, away from membranes to the core of lipid droplets, where they are less vulnerable to peroxidation. This study reveals an antioxidant role for lipid droplets that could be relevant in many different biological contexts

MIMS images from 3 planes and data from a full-thickness study.

<p><b>A</b>) ¹²C¹⁴N quantitative atomic mass images of a mouse sperm head extracted from planes 30, 100 and 200 out of 284 (image field = 15 µm×15 µm; 256×256 pixels; acquisition time per plane = 5.5 mins; total acquisition time = 27 hrs). Green circles: ROIs in sperm head (“N”) and in trehalose film (“T”) used to generate plots of ¹⁸O/¹⁶O values and ²⁸Si counts. <b>B</b>) ¹⁸O/¹⁶O ratios (circles) and ²⁸Si counts (diamonds) extracted from each plane from the ROIs shown in (A). The spikes in the ²⁸Si curves show the point at which the trehalose film (red diamonds) and the sperm head (orange diamonds) have been completely sputtered through. The vertical grey stripe indicates end of sperm head sputtering and the start of silicon exposure.</p

Reflection differential interference micrographs of two preparation methods.

<p><b>A</b>) Mouse sperm deposited drop-wise onto a silicon chip. <b>B</b>) Sperm prepared with spin casting. Bar is 50 µm.</p