scholarly journals The photobiology of the human circadian clock

2021 ◽  
Author(s):  
Robin A. Schoonderwoerd ◽  
Mischa de Rover ◽  
Jan A.M. Janse ◽  
Lydiane Hirschler ◽  
Channa R. Willemse ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Blue Light ◽  
Light Exposure ◽  
Light Response ◽  
Modern Society ◽  
Light Levels ◽  
Custom Made ◽  
General Expectation ◽  
Excitatory Responses ◽  
Direct Measures

In modern society, the widespread use of artificial light at night disrupts the suprachiasmatic nucleus (SCN), which serves as our central circadian clock. Existing models describe excitatory responses of the SCN to primarily blue light, but direct measures in humans are absent. The combination of state-of-the-art neuroimaging techniques and custom-made MRI compatible LED devices allowed to directly measure the light response of the SCN. In contrast to the general expectation, we found that SCN activity was suppressed by light. The suppressions were observed not only in response to narrowband blue light (λmax: 470nm) but remarkably, also in response to green (λmax: 515nm) and orange (λmax: 590nm), but not to violet light (λmax: 405nm). The broadband sensitivity of the SCN implies that strategies on light exposure should be revised: enhancement of light levels during daytime is possible with wavelengths other than blue, while during nighttime, all colors are potentially disruptive.

Photobiology of the symbiotic acoel flatworm Symsagittifera roscoffensis: algal symbiont photoacclimation and host photobehaviour

2010 ◽  
Vol 91 (1) ◽  
pp. 163-171 ◽  
Author(s):  
João Serôdio ◽  
Raquel Silva ◽  
João Ezequiel ◽  
Ricardo Calado
Keyword(s):  
Photosynthetic Activity ◽  
Light Exposure ◽  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Light Response ◽  
High Light ◽  
Symbiotic Association ◽  
Light Levels ◽  
Light Gradient ◽  
Custom Made

The symbiotic association between the acoel flatworm Symsagittifera roscoffensis and the prasinophyte microalgae Tetraselmis convolutae was studied regarding its photophysiology and photobehaviour. The photoacclimation status and the photophysiological responses to high light of the algal endosymbiont were studied non-destructively on individual S. roscoffensis using pulse amplitude modulated fluorometry. Specimens collected in an intertidal sandy shore were characterized regarding the maximum quantum yield of photosystem II (PSII), Fv/Fm, and the light response of photosynthetic activity, by constructing rapid light-response curves of the relative electron transport rate of PSII, rETR. The studied population could be considered as high light-acclimated when compared with other intertidal photosynthetic organisms (e.g. macroalgae), with the light-saturation parameter Ek averaging 250 μmol m−2 s−1. Light stress experiments showed S. roscoffensis to be able to withstand the exposure to high light without displaying signs of photoinhibition, suggesting the operation of efficient physiological photoprotective processes. The photobehaviour of S. roscoffensis was studied by characterizing the distribution of the flatworms under a light gradient, using a custom-made photoaccumulation chamber. The results showed a photoaccumulation pattern evidencing a clear avoidance of extreme low or high light levels, and with maximum photoaccumulation values being found for a range of irradiances (150–400 μmol m−2 s−1) that generally coincided with the optima for photosynthetic activity. This matching between the optimum light levels for photosynthetic activity and photoaccumulation suggested that S. roscoffensis may use vertical migration as a form of behavioural photoprotection. This behavioural response may be used to rapidly and flexibly control light exposure, avoiding photodamage to the endosymbiont photosynthetic apparatus by direct exposure to sunlight.

scholarly journals Transcriptome sequencing and global analysis of blue light-responsive genes provide clues for high carotenoid yields in Blakeslea trispora

2021 ◽  
Author(s):  
Xin Ge ◽  
Ruiqing Li ◽  
Xiaomeng Zhang ◽  
Jingyi Zhao ◽  
Yanan Zhang ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Exposure ◽  
Global Analysis ◽  
Light Response ◽  
Carotenoid Biosynthesis ◽  
Blakeslea Trispora ◽  
Rna Seq ◽  
Significant Differential Expression ◽  
Blue Light Response ◽  
Transcription Data

Abstract Blakeslea trispora has great potential uses in industrial production because of the excellent capability of producing a large quantity of carotenoids. However, the mechanism of light induced carotenoid biosynthesis even the structural and regulatory genes in pathways remain unclear. In this paper, we reported the first transcriptome study in B. trispora in which we have carried out global survey of expression changes of genes participated in blue light response. We verified that the yield of β-carotene reaching to 3-fold when transferred from darkness to blue light for 24 h and the enhancement of transcription levels of carRA and carB presented a positive correlation with the increase in carotenoid production. RNA-seq analysis revealed that 1124 genes were upregulated and 740 genes were downregulated respectively after blue light exposure. Annotation through GO, KEGG, Swissprot and COG databases showed 11119 unigenes compared well with known gene sequences, 5514 unigenes were classified into Gene Ontology, and 4675 unigenes were involved in distinct pathways. Among the blue light responsive genes, 4 genes (carG1, carG3, carRA and carB) identified to function in carotenoid metabolic pathways were dominantly upregulated. We also discovered that 142 TF genes belonging to 45 different superfamilies showed significant differential expression (p≤ 0.05), 62 of which were obviously repressed by blue light. The detailed profile of transcription data will not only allow us to conduct further functional genomics study in B. trispora, but also enhance our understanding of potential metabolic pathway and regulatory network involved in light regulated carotenoid synthesis.

scholarly journals Personalized Office Lighting for Circadian Health and Improved Sleep

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4569 ◽  
Author(s):  
Charikleia Papatsimpa ◽  
Jean-Paul Linnartz
Keyword(s):  
Time Window ◽  
Light Exposure ◽  
Mathematical Optimization ◽  
Modern Society ◽  
Well Being ◽  
Daily Activities ◽  
Circadian Pacemaker ◽  
Light Levels ◽  
Office Lighting ◽  
The Impact

In modern society, the average person spends more than 90% of their time indoors. However, despite the growing scientific understanding of the impact of light on biological mechanisms, the existing light in the built environment is designed predominantly to meet visual performance requirements only. Lighting can also be exploited as a means to improve occupant health and well-being through the circadian functions that regulate sleep, mood, and alertness. The benefits of well-lit spaces map across other regularly occupied building types, such as residences and schools, as well as patient rooms in healthcare and assisted-living facilities. Presently, Human Centric Lighting is being offered based on generic insights on population average experiences. In this paper, we suggest a personalized bio-adaptive office lighting system, controlled to emit a lighting recipe tailored to the individual employee. We introduce a new mathematical optimization for lighting schedules that align the 24-h circadian cycle. Our algorithm estimates and optimizes parameters in experimentally validated models of the human circadian pacemaker. Moreover, it constrains deviations from the light levels desired and needed to perform daily activities. We further translate these into general principles for circadian lighting. We use experimentally validated models of the human circadian pacemaker to introduce a new algorithm to mathematically optimize lighting schedules to achieve circadian alignment to the 24-h cycle, with constrained deviations from the light levels desired for daily activities. Our suggested optimization algorithm was able to translate our findings into general principles for circadian lighting. In particular, our simulation results reveal: (1) how energy constrains drive the shape of optimal lighting profiles by dimming the light levels in the time window that light is less biologically effective; (2) how inter-individual variations in the characteristic internal duration of the day shift the timing of optimal lighting exposure; (3) how user habits and, in particular, late-evening light exposure result in differentiation in late afternoon office lighting.

scholarly journals Difference in autonomic nervous effect of blue light depending on the angle of incidence on the eye

2020 ◽  
Author(s):  
Emi Yuda ◽  
Yutaka Yoshida ◽  
Norihiro Ueda ◽  
Junichiro Hayano
Keyword(s):  
Heart Rate ◽  
Blue Light ◽  
Light Exposure ◽  
Biological Effects ◽  
Modern Society ◽  
Order Effect ◽  
Angle Of Incidence ◽  
Tablet Devices ◽  
Light Emitting Devices ◽  
Significant Difference

Abstract Objective: Blue light has been attributed to the adverse biological effects caused by the use of smartphones and tablet devices at night. However, it is not realistic to immediately avoid nighttime exposure to blue light in the lifestyle of modern society, so other effective methods to reduce the unwanted influences should be investigated. Earlier studies reported that inferior retinal light exposure causes greater melatonin suppression than superior retinal exposure. We examined whether the autonomic responses to blue light depends on the angle of incidence on the eye. Results: In eight healthy subjects, blue light from organic electroluminescent lighting device (15.4 lx at subjects’ eye) was exposed from 6 angles (0º, 30º, 45º, 135º, 150º, and 180º) for 5 min each with a 10-min interval of darkness. After adjusting the order effect of angles, however, no significant difference was detected in autonomic indices of heart rate variability with the angle of incidence, except that the exposure from 45º caused lower heart rate than exposures from 0º, 150º, and 180º. Further researches on the physiological properties of the biological effects of blue light are needed to control and reduce the health risks of using blue-light-emitting devices.

scholarly journals Difference in autonomic nervous effect of blue light depending on the angle of incidence on the eye

2020 ◽  
Author(s):  
Emi Yuda ◽  
Yutaka Yoshida ◽  
Norihiro Ueda ◽  
Junichiro Hayano
Keyword(s):  
Heart Rate ◽  
Blue Light ◽  
Light Exposure ◽  
Biological Effects ◽  
Modern Society ◽  
Order Effect ◽  
Angle Of Incidence ◽  
Tablet Devices ◽  
Light Emitting Devices ◽  
Significant Difference

Abstract Objective: Blue light has been attributed to the adverse biological effects caused by the use of smartphones and tablet devices at night. However, it is not realistic to immediately avoid nighttime exposure to blue light in the lifestyle of modern society, so other effective methods to reduce the unwanted influences should be investigated. Earlier studies reported that inferior retinal light exposure causes greater melatonin suppression than superior retinal exposure. We examined whether the autonomic responses to blue light depends on the angle of incidence on the eye. Results: In eight healthy subjects, blue light from organic electroluminescent lighting device (15.4 lx at subjects’ eye) was exposed from 6 angles (0º, 30º, 45º, 135º, 150º, and 180º) for 5 min each with a 10-min interval of darkness. After adjusting the order effect of angles, however, no significant difference was detected in autonomic indices of heart rate variability with the angle of incidence, except that the exposure from 45º caused lower heart rate than exposures from 0º, 150º, and 180º. Further researches on the physiological properties of the biological effects of blue light are needed to control and reduce the health risks of using blue-light-emitting devices.

scholarly journals Antimicrobial Effect Of Visible Blue Light Used In A Minimally Invasive Intramedullary Fracture Stabilization System

2019 ◽  
Vol 4 (5) ◽  
pp. 216-222 ◽  
Author(s):  
Guido W. Van ◽  
Peter D. Croughs ◽  
Tjebbe Hagenaars ◽  
Michael H.J. Verhofstad ◽  
Esther M.M. Van
Keyword(s):  
Blue Light ◽  
Exposure Time ◽  
Side Effect ◽  
Light Exposure ◽  
Agar Plate ◽  
Future Research ◽  
Stabilization System ◽  
Temporary Reduction ◽  
Fracture Stabilization ◽  
Custom Made

Abstract. Introduction: Since 2009, the IlluminOss® System is being used as an intramedullary fracture treatment. The system is characterized by the use of blue light to polymerize liquid monomer after its infusion in a polyethylene terephthalate balloon. Very few infections of the material have been observed, which might be explained by the possible antimicrobial side-effect of the blue light used in this intramedullary fracture stabilization system. This study aimed to assess this antimicrobial (side-)effect on S. aureus.Methods: A suspension of 1.5 x 103 CFU/ml of 8325-4 S. aureus was placed into five, custom made, black delrin cylinders. The implant was placed into the cylinders and the light source was activated for 200, 400, 600, 800, or 1,000 seconds. 100 µL of the light exposed suspension was grafted on blood agar and placed in a 35 degrees Celsius incubator for 24 hours. Colonies on each agar plate were counted and compared to the control plates (no blue light exposure).Results: The control plates showed a mean of 85 ± 15 colonies per plate. A statistically significant decrease was observed after 600 seconds of exposure time; mean colony count of 63 ± 4 (p <0.05). The absolute reduction was 24 ± 14 after 600 seconds exposure time. At 800 and 1,000 seconds, no statistically significant reduction was found compared with the control plates (means 72 ± 10 and 83 ± 14 colonies, respectively).Conclusions: In this study only a temporary reduction of S. aureus was observed.If future research regarding the antimicrobial characteristics of blue light used in the IlluminOss® System is desired, it should focus on the need for oxygen and its availability and the dose and manner of applying the light.

Nighttime Blue Light Exposure and Breast Cancer

2021 ◽  
pp. 30-33
Author(s):  
David Jaynes ◽  
Paul Switzer
Keyword(s):  
Breast Cancer ◽  
Risk Factor ◽  
Blue Light ◽  
Shift Work ◽  
Light Exposure ◽  
Night Shift ◽  
Background Information ◽  
Common Disease ◽  
Essential Information ◽  
Night Shift Work

The purpose of this article is to provide background information and the current understanding of a less familiar cause of female breast cancer; exposure to ultraviolet light at night. Breast cancer is a common disease that causes significant morbidity and mortality in women. There are several risk factors for breast cancer, most of which are genetic and environmental in nature. An often-overlooked risk factor is exposure to blue light during night shift work, which decreases melatonin production. One of the many cancer-preventing properties of melatonin is to limit estrogen production. Increased lifetime exposure to estrogen is a well-known cause of breast cancer. Awareness of nighttime blue light exposure as a breast cancer risk factor by women doing night shift work and those exposed to nighttime light via smartphones and laptops, is essential information to know so that protective measures can be taken.

scholarly journals DASH-type cryptochromes – solved and open questions

2020 ◽  
Vol 401 (12) ◽  
pp. 1487-1493
Author(s):  
Stephan Kiontke ◽  
Tanja Göbel ◽  
Annika Brych ◽  
Alfred Batschauer
Keyword(s):  
Dna Repair ◽  
Circadian Clock ◽  
Blue Light ◽  
Dna Repair Enzymes ◽  
Repair Enzymes ◽  
Open Questions ◽  
Essential Components ◽  
Repair Activity ◽  
Almost All ◽  
Uv Lesions

AbstractDrosophila, Arabidopsis, Synechocystis, human (DASH)-type cryptochromes (cry-DASHs) form one subclade of the cryptochrome/photolyase family (CPF). CPF members are flavoproteins that act as DNA-repair enzymes (DNA-photolyases), or as ultraviolet(UV)-A/blue light photoreceptors (cryptochromes). In mammals, cryptochromes are essential components of the circadian clock feed-back loop. Cry-DASHs are present in almost all major taxa and were initially considered as photoreceptors. Later studies demonstrated DNA-repair activity that was, however, restricted to UV-lesions in single-stranded DNA. Very recent studies, particularly on microbial organisms, substantiated photoreceptor functions of cry-DASHs suggesting that they could be transitions between photolyases and cryptochromes.

Effects of pre-bedtime blue-light exposure on ratio of deep sleep in healthy young men

2021 ◽  
Author(s):  
Masao Ishizawa ◽  
Takuya Uchiumi ◽  
Miki Takahata ◽  
Michiyasu Yamaki ◽  
Toshiaki Sato
Keyword(s):  
Blue Light ◽  
Light Exposure ◽  
Young Men ◽  
Deep Sleep

scholarly journals A priori checking of the light-response and data quality before extended data collection in pump–probe photocrystallography experiments

2017 ◽  
Vol 73 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Philip Coppens ◽  
Anna Makal ◽  
Bertrand Fournier ◽  
Katarzyna N. Jarzembska ◽  
Radosław Kamiński ◽  
...  
Keyword(s):  
Data Collection ◽  
Light Exposure ◽  
A Priori ◽  
Light Response ◽  
Response Ratio ◽  
Full Data ◽  
Pump Probe ◽  
Ratio Correlation ◽  
Induced Signal

In picosecond and slower pump–probe diffraction experiments, collection of response–ratio correlation sets prior to full data collection provides an invaluable confirmation of the existence of a light-induced signal prior to full data collection. If a response to light exposure is observed, the quality of the data being collected can be assessed. A number of such correlation plots both for synchrotron and in-house pump–probe data collection are presented.

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