ИСТИНА

Contrary to metabolically-active RPE lipid droplets, cone drops are known first of all as tiny intracellular optical devices representing the same time both high-refraction lenses (due to drop geometry and refractive index of lipids), and color filters having unique absorption due to high concentration of carotenoids dissolved in lipids. Regarded as optical (i.e.,‘physical’) devices, cone oil-drops are routinely considered metabolically inert. However, as it had been recently found, carotenoid content of bird cone oil-drops may depend not only on diet (which seems rather natural), but (almost incredibly) even on illumination condition [Knott et al., 2010]. Metabolic aspects of these events were described at molecular level [Tomey et al., 2015]. In this context, of special interest become obvious data on active cone oil-droplet metabolism observed under electron microscope in birds and frogs (contained under bright, but not exactly defined illumination). Close apposition of ellipsoid mitochondria to droplet body (a), (b) loss of their distinct borders with droplet, (c) changes of their internal cristae, and (d) fine-structure changes of the droplet lipid mass, are surprisingly identical at the subcellular level picture of both big, metabolically-active frog RPE droplets and cone droplets of frogs and birds.