Biology subjects

Jeffery, G.

Publications and source records attributed to Jeffery, G..

8 recordsLinked to original sources

bioRxiv2026

The Hidden Cost of Blue Light: Multiorgan Pathology Induced by LED Exposure in Mice

Life evolved under broad-spectrum sunlight (300-3500 nm), but most modern light-emitting diodes (LEDs) emit within a restricted visible range (350-650 nm) leaving lighting environments that are short-wavelength dominant. We ask if chronic 450nm exposure dominant in LEDs alters metabolism and organ integrity in ageing mice environmentally exposed at 13 mW/cm{superscript 2} for 5 h/day over 40 weeks, at an intensity within the range of human environmental exposures. Mice exhibited progressive weight gain despite reduced food intake, with altered glucose tolerance and insulin sensitivity over time. White adipose tissue mass increased, while brown adipose tissue weight and UCP1 protein levels remained unchanged. Relative organ weights (heart, liver, kidney, testis) were each reduced by ~10%, with histopathology revealing fat deposition, hepatocellular degeneration, renal tubular damage, steatosis, and impaired testicular architecture. These findings demonstrate that chronic 450 nm light exposure is associated with metabolic alterations and multiorgan pathology in mice.

pathology↗

bioRxiv2026

Importance of the Unseen: Near-Infrared Light Regulates Human Glucose Levels in the Built Environment

Life evolved under broad spectrum sunlight (300-2500nm), but in the modern built environment under standard Light Emitting Diode (LED) illumination is restricted to around 400-650nm. Different wavelengths influence metabolism via mitochondria. 670-900nm support mitochondrial function while those in the Soret band (420-450nm) undermine mitochondrial ability. Under LED lighting, metabolism is challenged with reduced mitochondria ability, and hence, reduced demand for blood sugars that are required to produce adenosine triphosphates (ATP). As longer wavelengths enhance mitochondrial performance, they increase demand for blood sugars, reducing serum glucose. Here we change the lighting in windowless offices providing either standard LED desk lamps or those supplemented with 850nm in real-world environments. This was for two hours every morning over three days. We then assessed blood sugars with two independent methods, an oral glucose tolerance test and continuous glucose monitoring. Subjects exposed to standard LEDs had significantly increased blood sugars, while those exposed to lamps with added 850nm had significantly reduced blood sugars. These real-world data highlight the importance of light in controlling metabolism. They raise issues concerning public health in interior environments where we now spend >90% of our lives.

physiology↗

bioRxiv2026

Metabolism in the Solar Photon Field A physical framework for photon-assisted modulation of mitochondrial electron-transfer kinetics

Within a single human lifetime, the spectral environment has been fundamentally reshaped. Broadband daylight, rich in infrared (IR) photons arising from solar and atmospheric physics, has been replaced in the built environment by narrow, engineered spectra that largely exclude long wavelengths. While modern lighting is optimised for vision, the non-visual photobiology of metabolism may depend on spectral components that are now absent. When expressed in photon-energy units, the solar spectrum exhibits a broad maximum near 0.75 eV. This range overlaps with the activation and reorganisation energies governing mitochondrial electron-transfer kinetics. Within a Marcus-type framework, IR photons are therefore positioned to modulate rate-limiting metabolic steps by biasing barrier-crossing probabilities rather than supplying chemical energy. These wavelengths also penetrate deeply into tissue in a scattering-dominated regime, forming a diffuse internal photon field capable of interacting with distributed mitochondrial networks. We propose the term photometabolism: a solar-driven, non-photosynthetic modulation of core metabolic processes. A scaling analysis shows that photon interception in this band varies with body mass in parallel with basal metabolic rate, suggesting that ambient sunlight provides sufficient flux to influence metabolic kinetics across the biosphere. These findings have implications for physiology, ecology and the design of indoor environments whose lighting spectra increasingly diverge from their evolutionary context.

biophysics↗

bioRxiv2023

A Ray of Light Against Age Related Neurodegeneration

Mitochondrial function declines with age and many pathological processes of neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Through combined theoretical Monte Carlo light modelling and practical 31P Magnetisation Transfer Magnetic Resonance Spectroscopy (MT-MRS) we quantify the effects of 670 nm PBM treatment on healthy aging brains. 31P MT-MRS revealed a significant increase in the rate of ATP flux after PBM in a sample of older adults. Light modelling shows 1% absorption in grey matter and confirms absorption peaks at 670 and 820 nm. Our study provides evidence of PBM therapeutic efficacy and strengthens confidence in PBM as an acceptable healthcare technology to improve mitochondrial function and human health.

neuroscience↗

bioRxiv2022

Mitochondrial decline in the ageing old world primate retina: little evidence for difference between the centre and periphery

Mitochondrial decline is a key feature of ageing. The retina has more mitochondria than any other tissue and ages rapidly. To understand human retinal ageing it is critical to examine old world primates that have similar visual systems to humans, and do so across central and peripheral regions, as there is evidence for early central decline. Hence, we examine mitochondrial metrics in young and ageing Macaca fascicularis retinae. In spite of reduced ATP with age, primate mitochondrial complex activity did not decline. But mitochondrial membrane potentials were reduced significantly, and concomitantly, mitochondrial membrane permeability increased. The mitochondrial marker Tom20 declined significantly, consistent with reduced mitochondria number, while VDAC, a voltage dependent anion channel and diffusion pore associated with apoptosis increased significantly. In spite of these clear age-related changes, there was almost no evidence for regional differences between the centre and the periphery. Primate cones do not die with age, but many showed marked structural decline with vacuous spaces in proximal inner segments normally occupied by endoplasmic reticulum (ER), that regulate mitochondrial autophagy. In many peripheral cones, ER was displaced by the nucleus that transposed across the outer limiting membrane and could become embedded in mitochondrial populations. These data are consistent with significant changes in retinal mitochondria in old world primate ageing but provide little if any evidence that aged central mitochondria suffer more than those in the periphery.

neuroscience↗

bioRxiv2021

Long wavelength light that improves aged mitochondrial function selectively increases cytokine expression in serum and the retina

Aged mitochondrial function can be improved with long wavelength light exposure. This reduces cellular markers of inflammation and can improve system function from fly though to human. Here, we ask what impact 670nm light has on cytokine expression using a 40 cytokine array in blood serum and retina in C57Bl6 mice. There was a relatively uniform increase in cytokine expression between 3 and 12 months of age in serum and retina. 670nm exposure was delivered daily for a week in 12 month old mice. This shifted patterns of cytokine expression in both serum and retina inducing a selective increase with some in serum increasing >5 fold. Changes in retina were smaller. In serum there were major increases in IL-7, 6, 13, 16 and 23, also in TNF- and CXCL 9 and 10. In retina the increases were found mainly in some IL (interleukins) and CXCLs (chemokines). A few cytokines were reduced by light exposure. Changes in serum cytokines implies that long wavelengths impacts systemically even to unexposed tissues deep in the body. In the context of wider literature, increased cytokine expression may be protective. However, their upregulation by light merits further analysis as cytokines upregulation can also be negative.

molecular biology↗

bioRxiv2021

The morning burst: Shifting daily patterns of ATP production in Drosophila and temporal windows for their improvement in ageing

Mitochondria produce energy for cell function via adenosine triphosphate (ATP) and are regulated by a molecular 24h clock. Here we use Drosophila melanogaster to reveal shifts in whole animal ATP production over 24h, showing a marked peak in the morning that declines around midday and remains low from then through to the following morning. Mitochondrial membrane potential and ATP production has been shown previously to improve after long wavelength exposure, but apparently not at all times. Hence, to explore this further we exposed flies to 670nm at different times. Exposures between 08.00 and 11.00 resulted in a significant increase in ATP, while exposures at other times had no effect. Within the morning window, not all times were equally effective, however, 670nm exposure mid-morning when ATP production was maximal did not increase ATP, possibly because mitochondria lacked spare capacity at this time. Hence, in the morning there is a complex dynamic relationship between long wavelength light and mitochondria. Mitochondrial function and the influence of long wavelengths are conserved across species from fly to human, and determining the time points for light administration to improve function in ageing and disease is of key importance. Our data progress this search and reveal the outline of these times.

physiology↗

bioRxiv2020

Red light corrects neonicotinoid induced immunodeficiency and impaired respiration in poisoned bumblebees

Neonicotinoid pesticides undermine mitochondrial function in insects including bumblebees, reducing ATP, mobility and leading to death. They also reduce bumblebee immunocompetency leaving them vulnerable to pathogen attack. This undermines key pollinators critical in the agricultural economy. However, 670nm light exposure improves mitochondrial function undermined by age or disease, increasing respiratory chain efficiency, improving ATP production, mobility and survival in bumblebees and fruit flies. Here we show that 670nm restores immunocompetence, improving hemocyte counts and hemolymph anti-microbial action. Additionally, we measure whole body respiration in vivo in individual bumblebees revealing that it is a functional metric of both neonicotinoid impact and light induced mitochondrial protection. Critically we show that only 1 min 670nm exposure is sufficient to correct respiratory deficits induced by pesticide and restore normal immune ability. Longer exposures are not more effective. Further, single 1 min exposure protects respiration and immunity for approximately 3-6 days. Hence, 670nm impact is not dose dependent but switch like. These data provide a compelling rational for 670nm application to protect pollinators on which a major part of the agro economy is based and who are being challenged by aggressive pesticide application.

immunology↗