Chlorophyll derivatives enhance invertebrate red-light and ultraviolet phototaxis

Abstract

Chlorophyll derivatives are known to enhance vision in vertebrates. They are thought to bind visual pigments (i.e., opsins apoproteins bound to retinal chromophores) directly within the retina. Consistent with previous findings in vertebrates, here we show that chlorin e6 — a chlorophyll derivative — enhances photophobicity in a flatworm (Dugesia japonica), specifically when exposed to UV radiation (λ = 405 nm) or red light (λ = 660 nm). This is the first report of chlorophyll derivatives acting as modulators of invertebrate phototaxis, and in general the first account demonstrating that they can artificially alter animal response to light at a behavioral level. Our findings show that the interaction between chlorophyll derivatives and opsins virtually concerns the vast majority of bilaterian animals, and also occurs in visual systems based on rhabdomeric (rather than ciliary) opsins.

Structural and Functional Consequences of the Weak Binding of Chlorin e6 to Bovine Rhodopsin

“…To confirm that Ce6 actually enhances bovine rhodopsin's sensitivity to red light as reported in a number of previous studies (8,10,11,34), we applied our Ce6 subtraction protocol to rhodopsin illuminated with red light (see Materials and Methods). We were able to confirm that the presence of Ce6 enhances bleaching rates not only in retina extracts, but also in our purified system containing only bovine rhodopsin, dodecyl maltoside and Ce6 (Fig.…”

First‐Pass Metabolism of Chlorophylls in Mice

“…These studies implied the intravenous administration of chlorin e 6 photosensitizers and the posterior localization of these compounds in the liver and other tissues . In addition, the presence of chlorin e 6 in the retina of several animals have been shown to enhance the red vision . However, our data reveal (Table ) that a chlorin e 6 counterpart is accumulated in liver because of the metabolism of parent derivatives through processes that modify the macrocycle, rather than through intravenous administration, an unprecedented result in the literature.…”

“…Recent discoveries have shown the specific functions of several chlorophyll metabolites of developing in animal tissues, including the production of ATP, the regulation of the redox status in plasma, implications as visual pigments, and activation of specific nuclear receptors that could control lipid abnormalities in common diseases such as obesity, diabetes, and hyperlipidemia among others. Evidently, the origin of chlorophyll metabolites present in the animal body is circumscribed to the diet.…”

Artificially altered gravity elicits cell homeostasis imbalance in planarian worms, and cerium oxide nanoparticles counteract this effect

“…The asexual strain GI of the planarian Dugesia japonica (Tricladida Dugesiidae) 41 was bred in artificial water (CaCl 2 2.5 mM, NaHCO 3 0.8 mM, MgSO 4 0.4 mM, KCl 0.077 mM in distilled water) at 18°C 42 . Planarians were transferred to ESA‐ESTEC, in Noordwijk (The Netherlands), in boxes filled with artificial water at the temperature of about 22°C.…”