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Few studies have been devoted to the effects of color on fish and most of them are not directly concerned with stress. As far as we know, this is the first study showing such a cortisol-suppressing effect of environmental light color in fish. Other reports have focused on the effects of environmental color on behavior 4,5,16 , growth and survival 6. Effects of color background on chromatophore-regulating hormones have also been reported and Groneveld et al. However, the present study supports the idea that color influences this axis, thus showing that color may affect different biological systems.

The effects of environmental color have been investigated using mainly background color instead of light color. Although background color is probably more useful for recommendations of color of interior aquarium walls, light color - like those used in the present study - may also have practical consequences for indoor fish production or even fish transportation.

Moreover, if the light color has an effect on fish physiology, the color of the inner walls of containers or aquaria should also be chosen accordingly. Which color should this be? The present study showed that blue light was an effective inhibitor of the stress-induced cortisol response in the Nile tilapia. However, other colors have been shown to improve fish welfare in other species, such as green and blue in Sardinops caerulea 4 , Oplegnathus fasciatus , Monocanthus cirrhifer , Cybium niphonium , Spheroides niphobles and Sphyraena japonica 5 , green in Brycon cephalus 10 , and light grey in perch larvae, Perca fluviatilis 6.

In diurnal fish, vision is the main sensory modality 4 and cone cells have been reported to be present 1,2 , thus supporting an evolutionary significance for color discrimination in fish. Since in natural habitats environmental color is a characteristic which varies according to place, and may even change over time in the same habitat, the effect of color on the fish's life is expected to be associated with the predominant habitat color. According to Levine and MacNichol Jr. Therefore, color effects on a fish's life seem to be a species-dependent phenomenon which may be related to specific habitat characteristics.

Fanta 16 argues that a blue background increases aggression in the Nile tilapia, and suggests that this color is not adequate for holding containers for this species. Conversely, the present data show that blue light has a protective role against stress for this same species. In fact, Schreck 18 suggests that conditions inducing behaviors differing from the standard pattern of the species may be supposed to be stressors, thus indicating that behaviors are reliable indicators of stress in fish.

However, behavior interpretation must consider the environmental and evolutionary history of each species. Thus, aggression in the Nile tilapia should be interpreted considering its territorial habits In fact, intraspecific aggression in territorial species is a natural behavior expected to be expressed when the fish are adjusted to their environment stressors might decrease intraspecific aggression.

Thus, the increased aggression caused by the blue background in the Nile tilapia reported by Fanta 16 may indicate that the fish were more comfortable. This fish was more aggressive under green light and grew almost three times as much in this color, a finding supporting that this increased intraspecific aggression might imply that these fish were unstressed. Therefore, we reinforce that blue light improves the welfare of the Nile tilapia.

UL weighs in on human-centric lighting, certifying an LED for low blue levels

A last comment concerns the effect of light intensity or light color. Light intensity has been shown to affect several processes in fish 19,20 and light color or color background may affect light intensity. In the present study, the light intensities measured in lux of blue and green colors were the same, but the impact of these colors on the fish was strongly different.

Thus, light intensity was probably not involved. The control condition showed a much higher light intensity; even so, these fish reacted in a manner similar to that of fish under green color with a low lux value. Of course, these comments do not consider other light characteristics, such as wavelength. However, the present study emphatically shows that light color affects the life of Nile tilapia, opening new possibilities for further studies. Color vision in fish. Scientific American , Nicol JAC Some aspects of photoreception and vision in fishes.

Academic Press, London. Heichenbach-Klinke HH Enfermedades de los Peces. Editora Acribia, Zaragoza, Spain.

How Blue Light Affects Mental Health

Behavior and reactions of the pacific sardine, Sardinops caerulea Girard , under the influence of white and colored lights and darkness. Proceedings of the California Academy of Sciences , The influence of wave lengths of light on the behavior of young fish. Tank wall colour and light level affect growth and survival of Eurasian perch larvae Perca fluviatilis L.

Aquaculture , Social control of growth in fish. Brazilian Journal of Medical and Biological Research , Effect of confinement stress on circulating levels of growth hormone and two prolactins in freshwater-adapted tilapia Oreochromis niloticus. The UL certification is the latest recognition of a link between modern LED lighting and human health. The science of human-centric lighting, also known as circadian lighting or lighting for health and wellbeing, is still very much in its early days.

While many scientists believe that there is a link, not all experts agree on the specific causes and effects. For example, the American Medical Association has recommended that when municipalities install new streetlights, they should use K or warmer. But that strict CCT perspective clashes with the spectral power perspective that others advocate. Rather, other factors associated with late night iPad use were the culprit — factors such as screen brightness as well as the general stimulation of usage.

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The finding was a surprise because blue light from gadgets at night has gained a reputation for being a particular culprit in sleep disturbance. The discussions and debates will not be going to bed anytime soon. LEDs Magazine will continue to update you. Blue-free white light breaks the paradigm of circadian lighting. Circadian scientists who have studied light's impact win Nobel.

Multi-channel SSL system enhances health and wellbeing in residential retrofit - Part 1. At a plugfest in Valencia, Spain, nine companies won certification for TALQ-compliant products, paving the way for interoperable smart city networks and applications from multiple vendors. Feedback on our previous PoE blog has shown a range from compliments to concerns with regard to the technology.

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Materials and Methods: Two cell lines and irradiation with blue light were used. Cell mortality and a possible mechanism of action were investigated. These results led us to expose a patient with haemorrhagic cutaneous melanoma metastasis to blue light. Irradiation led to an immediate arrest of haemorrhage, an inhibition of tumour growth and extensive tumour necrosis 24h after irradiation. Conclusion: Exposure to blue light may offer new approaches to the treatment of superficial skin carcinomas in humans.

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Melanoma is highly resistant to conventional chemotherapeutic agents and novel approaches are needed especially to treat subcutaneous tumours. Photodynamic therapy using cancer-designed photosensitizers and laser beams has been increasingly used in clinical medicine. The visible light at a wavelength corresponding to the drug absorption activates these agents and induces highly cytotoxic products: singlet molecular oxygen and oxygen radicals 1. Most papers have used red and sometimes infrared light to penetrate deeper into tissues and these wavelengths have previously displayed significant efficacy in treating pigmented melanoma.

Blue light has rarely been used in photodynamic therapy due to its poor penetration in the skin. The effects of blue light have mainly been used in humans to treat hyperbilirubinaemia in infantile jaundice 2. In a limited number of studies, blue light has been shown to disrupt mitosis and mitochondrial activity 3. Other studies have suggested that blue light exerts a cytostatic effect on B16 melanoma cells 4. Recently, Lockwood et al. For this reason, blue light has been proposed for a treatment of various carcinomas including melanoma, haematopoietic cell line carcinomas, squamous cell carcinoma etc.

The mechanisms by which blue light interacts with its biological targets and provokes cellular damage still remain unclear. In this study, the effects of blue light on melanoma cells and endothelial cells in comparison to red light were examined. Also a patient with haemorrhagic subcutaneous metastasis of melanoma was exposed to blue light. The culture medium was changed every 3 days. The cells were subcultured by dispersal with trypsin-EDTA and replated at a split. PDT L. A mobile unit was equipped with a three module-reflecting head revolving around two axes.

The special arrangement of the lamps and special reflector geometry for optimal intensity created a homogenous irradiation field and thus uniform and intense irradiation. These lamps irradiated within the nm range with a maximum at nm. The irradiation unit was ventilated by integrated fans. PhotoDyn At a distance of 25cm from the device length of the spacing rod , the area of the homogeneous irradiation field had a diameter of 10 cm.

The orange filter allows red light therapy with a spectrum from nm to nm with a maximum at nm.

Irradiation protocol. No photosensitizer was added to the wells. The fluence rate was 10 W per cm 2. The distance between the end of the optical fiber and the microplates were set to 37 cm blue light and 25 cm red Light. During cell illumination temperature was monitored at the top of the microplate.

Cytotoxic and photocytotoxic studies. Cell viability was measured by the MTT [3- 4.

Effects of blue light on enzymes

Optical density measurements were performed before and then immediately after the end of irradiation, and 24 h, 48 h, 72 h and 96 h after the end of the irradiation. Phototoxicity of red and blue light on murine melanoma B16F10 cells. To determine the accuracy of the MTT assays for each experiment, two measurement points were routinely checked using the trypan blue exclusion test on a random basis. Lipid peroxidation.

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Lipid peroxidation products malondialdehyde MDA , other aldehydes and lipid hydroxiperoxides reacts with thiobarbituric acid TBA to yield a complex so called TBARS , spectroscopically detected at nm. The reaction is favored under acidic conditions and at high temperature. The reaction was stopped by cooling test tubes in ice. The colored complex was extracted by addition of 1 ml n -butanol, for which absorbance was measured at nm on a Shimadzu UVPC spectrophotometer.

Statistical analysis. For comparison between the visible light blue or red exposure group and the control group, the Kruskal-Wallis test was used to detect differences in the average. Phototoxicity of blue and red light on bovine endothelial cells, by the colorimetric MTT assay.

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