Mitochondria are specifically vulnerable to 420nm light in drosophila which undermines their function and is associated with reduced fly mobility

Abstract

Increased blue light exposure has become a matter of concern as it has a range of detrimental effects, but the mechanisms remain unclear. Mitochondria absorb short wavelength light but have a specific absorbance at 420nm at the lower end of the human visual range. This 420nm absorption is probably due to the presence of porphyrin. We examine the impact of 420nm exposure on drosophila melanogaster mitochondria and its impact on fly mobility. Daily 15 mins exposures for a week significantly reduced mitochondrial complex activities and increased mitochondrial inner membrane permeability, which is a key metric of mitochondrial health. Adenosine triphosphate (ATP) levels were not significantly reduced and mobility was unchanged. There are multiple options for energy/time exposure combinations, but we then applied single 420nm exposure of 3h to increase the probability of an effect on ATP and mobility, and both were significantly reduced. ATP and mitochondrial membrane permeability recovered and over corrected at 72h post exposure. However, despite this, normal mobility did not return. Hence, the effect of short wavelengths on mitochondrial function is to reduce complex activity and increasing membrane permeability, but light exposure to reduce ATP and to translate into reduced mobility needs to be sustained.

Lethal effect of blue light on Asian tiger mosquito, Aedes albopictus (Diptera: Culicidae)

“…albopictus through all developmental stages except for eggs. For example, mitochondria are known to specifically absorb ~ 420-nm light, and this absorption is attributed to the presence of porphyrins 38 . In addition, it has been reported that the absorption of wavelengths of ~ 420 nm by porphyrins interacts with triplet oxygen molecules to form radicals and ROS, leading to cell death [39][40][41][42][43] .…”

Chronic blue light leads to accelerated aging in Drosophila by impairing energy metabolism and neurotransmitter levels

“…There is increasing evidence that BL has the potential to damage human eyes contributing to diseases ranging from glaucoma (Ouyang et al, 2020) to retinal degeneration and age-related maculopathy (Algvere et al, 2006); however, little is known about the mechanisms of damage. Recent research on BL effects focused on human retina-related cells in vitro and suggest that BL can increase reactive oxygen species (ROS), cause DNA damage, impair mitochondrial function, and damage lysosomes (Ouyang et al, 2020;Kam et al, 2021). An in vivo model of acute BL phototoxicity was developed in the fruit fly, Drosophila melanogaster.…”

Systemic glucose levels are modulated by specific wavelengths in the solar light spectrum that shift mitochondrial metabolism

“…Optical stimulation of mitochondria with specific wavelengths present in natural light modulates their respiration rate, ATP production and impacts on general physiology, a process known as photobiomodulation. 420 nm light is absorbed by mitochondria [ 1 ], specifically the chromophore porphyrin located in the inner mitochondrial membrane. Following 420 nm absorption, porphyrins interact with molecular triplet oxygen to form singlet oxygen, superoxide anion, and hydroxyl radicals.…”

“…670 nm and other longer wavelengths differs in their impact. They are not absorbed by mitochondria directly [ 1 , 3 , 4 ]. Instead, the mechanism of action is proposed to be via light absorption by nanoscopic interfacial water layer surrounding mitochondrial ATP rotor pumps.…”