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What is blue light?

What is blue light?



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What is the "blue light" often discussed in relation to human melatonin production, sleep/wake cycles, etc.? A Google search seems to define it as light of a particular wavelength, suggesting that it literally means "light that's blue in color," but many articles seem to attribute blue light to the light emitted from computer/TV/etc. screens, which is not inherently blue in color.

What exactly is blue light? For example, would adjusting the "blueness" of a colored light bulb, as if raising and lowering the "B" slider in an "RGB" color selector (raising "B" in the morning and lowering "B" in the evening), have at least a hypothetical positive impact on human circadian rhythms?


Blue light means wavelengths that appear to the human eye as blue when they are presented alone. This light is important for sleep/wake cycle regulation because this is the wavelength that cells that participate in this regulation respond to.

"White light" is light that covers the full visible spectrum; sunlight, for example, is fairly white. However, that light contains plenty of blue light as well as all the other colors - there is no actual wavelength for "white," it is a collection of all the other wavelengths.

Similarly, TVs and other screens emit red, green, and blue light. Because of our makeup of photoreceptors, this is sufficient to mimic any visible color. When referring to the blue light of televisions, people are referring to that blue component. If you disabled the blue channel somehow you would get a very strange picture but also activate less the cells that sense daylight based on blue light.

The reason screens are so problematic is that people stare directly at them and take in a lot of light. Other sources of bright, whitish light would have the same effect.


Blue light may not be as bad for sleep as suspected, new study argues

For the last few years, general scientific consensus has suggested the blue light spectrum coming out of our modern devices can significantly disrupt our circadian rhythms. To balance this, many devices now come with night modes, offering yellow or sepia screen filters designed to cut out the most problematic blue spectrums of light. Now a new study from the University of Manchester is questioning that common consensus, arguing perceived color can also influence circadian clocks, and novel animal studies may reveal exposure to yellow light at night could be confusing our body clocks.

Alongside the rods and cones in our eyes we have a small amount of innately photosensitive cells. These cells are designed to not help us see, but rather sense light as part of our circadian management system. When these specific retinal cells sense light, they produce a molecule called melanopsin, which directly tells certain parts of our brain to stay awake and alert. As well as suppressing melatonin, melanopsin has been found to help regulate and set our body's circadian rhythm.

The popular blue light hypothesis arose from research finding melanopsin is most sensitive to a wavelength of light around 480 nanometers. This is a blue spectrum of light, and it tends to be the most prominent spectrum displayed by the LED screens used in many of our modern digital devices, from smartphones to laptops.

“There is lots of interest in altering the impact of light on the clock by adjusting the brightness signals detected by melanopsin but current approaches usually do this by changing the ratio of short and long wavelength light this provides a small difference in brightness at the expense of perceptible changes in color,” explains Tim Brown, corresponding author on the new study. “We argue that this is not the best approach, since the changes in color may oppose any benefits obtained from reducing the brightness signals detected by melanopsin.”

To study the particular influence of color on circadian systems the researchers conducted a series of experiments on mice with altered cone spectral sensitivity. Using polychromatic lighting the study discovered yellow light conferred a greater impact on the animals’ circadian behaviors than blue light.

The researchers go on to hypothesize this innate circadian relationship with color can be related to the organic changes in light composition across twilight in any 24-hour period. The suggestion is the shift towards blue light that accompanies the sun setting is a fundamental influence on our circadian clock.

“We show the common view that blue light has the strongest effect on the clock is misguided in fact, the blue colors that are associated with twilight have a weaker effect than white or yellow light of equivalent brightness,” says Brown.

This certainly isn’t the first research to explore how the chromatic characteristics of light influence circadian rhythms. However, it is the first to explicitly suggest the perceived color of light can be as influential to circadian systems as spectrums of light that modulate melanopsin.

The research seems implicitly critical of those digital device “night modes” which add a warm yellow hue to screens in the evening. But it is important to note that this new study was only conducted on mice, and although the researchers are confident there is evidence to suggest the effect detected could extend to humans, there is no evidence that the perceived color of light is significantly influential on human circadian systems. In fact, some research has been conducted revealing interventions such as wearing amber-tinted glasses for an hour or two before going to bed may enhance the quality of a person’s sleep.

While it may be clear blue wavelengths of light activate circadian-regulating mechanisms in the human brain, it is not clear yet whether a yellow-filter on a device’s screen markedly influences the human circadian system. So you don’t necessarily need to go and switch off that night mode on your laptop just yet.


What&rsquos the explanation for these mysterious blues?

In the case of birds, there is no one principle mechanism. Different birds follow a variety of mechanisms, from microscopic bead design to maintaining a uniform crystal structure. The bluejay feather consists of the bead design, which is quite messy in nature. These beads scatter light in such a manner that only blue light is able to escape, whereas peacock feathers have microscopic lamallae that cause the interference. Also, if you have blue eyes, that blue is also based on the structure &ndash not any pigments!

Bluejay feather & Peacock feather (Photo Credit: Thomas Bresson / Wikimedia Commons & Flickr)

How does it work?

Before we look at how butterflies to do it, we need to understand a bit of physics. Now, this appearance of the color blue is due to the microscopic structure of the scales and a concept called interference of light.

Interference of light takes place when two rays of light collide. This results in either a ray of light with higher intensity (Constructive Interference CI) or no light at all (Destructive interference DI). Light is basically a wave, and as such, it has crests and troughs. When the two rays collide and the crests or troughs overlap one another, CI takes place and the waves are said to be &lsquoin phase&rsquo. However, if a crest overlaps a trough, then DI takes place and the waves are said to be &lsquoout of phase&rsquo.

Thus, when we zoom into the structure of the scale, we can observe ridge-like structures that are parallel to one another. When light hits the ridges and its branches, some of the light will reflect off the top layer, while the rest enters the branch. A part of the light that passes through the branch is reflected off the bottom layer of the same branch. This gives us two rays of light with equal wavelength and intensity. For most colors, the reflected light rays will be &lsquoout of phase&rsquo, so we don&rsquot see those colors. However, in the case of the color blue, the two light rays that reflect off the ridge are perfectly &lsquoin phase&rsquo, meaning that they do not cancel each other out, allowing us to see the blue color. The light rays passing through are also bending at the correct angle, which helps cause the blue color.

Representation of ridges and how they function (Blue Morpho Butterfly)

The only butterfly that is known to produce a blue pigment is called the &lsquoOlivewing&rsquo butterfly. Until now, little has been known about this unique creature or how it produces the pigment (Florida Museum of National History).

Can they lose their blue color?

What if we change the refractive index of the wings, i.e., change the angle at which the light bends while passing through the ridges won&rsquot that put the rays &ldquoout of phase&rdquo? If that happens, we won&rsquot be able to see the blue color. The question is, how can we change the refractive index? By simply filling the space in the ridges with some other material instead of air! Every material has its own refractive index, as they bend light at different angles, which means that even water can change the angle. If that&rsquos the case, these butterflies will lose their color as soon as it rains, right? The answer is &ldquoNo&rdquo. Thanks to evolution, the wings are made of a material that is naturally water resistant! The feathers are covered with a hydrophobic coating that helps them stay dry.


Blue-light photoreceptors in higher plants

In the past few years great progress has been made in identifying and characterizing plant photoreceptors active in the blue/UV-A regions of the spectrum. These photoreceptors include cryptochrome 1 and cryptochrome 2, which are similar in structure and chromophore composition to the prokaryotic DNA photolyases. However, they have a C-terminal extension that is not present in photolyases and lack photolyase activity. They are involved in regulation of cell elongation and in many other processes, including interfacing with circadian rhythms and activating gene transcription. Animal cryptochromes that play a photoreceptor role in circadian rhythms have also been characterized. Phototropin, the protein product of the NPH1 gene in Arabidopsis, likely serves as the photoreceptor for phototropism and appears to have no other role. A plasma membrane protein, it serves as photoreceptor, kinase, and substrate for light-activated phosphorylation. The carotenoid zeaxanthin may serve as the chromophore for a photoreceptor involved in blue-light-activated stomatal opening. The properties of these photoreceptors and some of the downstream events they are known to activate are discussed.


Daily exposure to blue light may accelerate aging, even if it doesn't reach your eyes

Prolonged exposure to blue light, such as that which emanates from your phone, computer and household fixtures, could be affecting your longevity, even if it's not shining in your eyes.

New research at Oregon State University suggests that the blue wavelengths produced by light-emitting diodes damage cells in the brain as well as retinas.

The study, published today in Aging and Mechanisms of Disease, involved a widely used organism, Drosophila melanogaster, the common fruit fly, an important model organism because of the cellular and developmental mechanisms it shares with other animals and humans.

Jaga Giebultowicz, a researcher in the OSU College of Science who studies biological clocks, led a research collaboration that examined how flies responded to daily 12-hour exposures to blue LED light -- similar to the prevalent blue wavelength in devices like phones and tablets -- and found that the light accelerated aging.

Flies subjected to daily cycles of 12 hours in light and 12 hours in darkness had shorter lives compared to flies kept in total darkness or those kept in light with the blue wavelengths filtered out. The flies exposed to blue light showed damage to their retinal cells and brain neurons and had impaired locomotion -- the flies' ability to climb the walls of their enclosures, a common behavior, was diminished.

Some of the flies in the experiment were mutants that do not develop eyes, and even those eyeless flies displayed brain damage and locomotion impairments, suggesting flies didn't have to see the light to be harmed by it.

"The fact that the light was accelerating aging in the flies was very surprising to us at first," said Giebultowicz, a professor of integrative biology. "We'd measured expression of some genes in old flies, and found that stress-response, protective genes were expressed if flies were kept in light. We hypothesized that light was regulating those genes. Then we started asking, what is it in the light that is harmful to them, and we looked at the spectrum of light. It was very clear cut that although light without blue slightly shortened their lifespan, just blue light alone shortened their lifespan very dramatically."

Natural light, Giebultowicz notes, is crucial for the body's circadian rhythm -- the 24-hour cycle of physiological processes such as brain wave activity, hormone production and cell regeneration that are important factors in feeding and sleeping patterns.

"But there is evidence suggesting that increased exposure to artificial light is a risk factor for sleep and circadian disorders," she said. "And with the prevalent use of LED lighting and device displays, humans are subjected to increasing amounts of light in the blue spectrum since commonly used LEDs emit a high fraction of blue light. But this technology, LED lighting, even in most developed countries, has not been used long enough to know its effects across the human lifespan."

Giebultowicz says that the flies, if given a choice, avoid blue light.

"We're going to test if the same signaling that causes them to escape blue light is involved in longevity," she said.

Eileen Chow, faculty research assistant in Giebultowicz's lab and co-first author of the study, notes that advances in technology and medicine could work together to address the damaging effects of light if this research eventually proves applicable to humans.

"Human lifespan has increased dramatically over the past century as we've found ways to treat diseases, and at the same time we have been spending more and more time with artificial light," she said. "As science looks for ways to help people be healthier as they live longer, designing a healthier spectrum of light might be a possibility, not just in terms of sleeping better but in terms of overall health."

In the meantime, there are a few things people can do to help themselves that don't involve sitting for hours in darkness, the researchers say. Eyeglasses with amber lenses will filter out the blue light and protect your retinas. And phones, laptops and other devices can be set to block blue emissions.

"In the future, there may be phones that auto-adjust their display based on the length of usage the phone perceives," said lead author Trevor Nash, a 2019 OSU Honors College graduate who was a first-year undergraduate when the research began. "That kind of phone might be difficult to make, but it would probably have a big impact on health."


Difference Between GFP and EGFP

Definition

GFP: A wild-type protein that exhibits green fluorescence under blue or UV light and naturally occurs in the jellyfish, Aequorea Victoria

EGFP: A variant of the wild-type GFP with higher-intensity emission with respect to GFP

Stands for

GFP: Green Fluorescence protein

EGFP: Enhanced green fluorescence protein

Origin

GFP: Wild-type

EGFP: Mutant

64 th Amino Acid

GFP: Phenylalanine

EGFP: Leucine

65 th Amino Acid

GFP: Serine

EGFP: Threonine

Brightness of the Color

GFP: Bright green

EGFP: Brighter green

Excitation Peaks

GFP: Two peaks (395 nm and 490 nm)

EGFP: Single peak (490 nm)

Folding Efficiency at 37 °C

Conclusion

GFP is the wild-type protein that exhibits bright green fluorescence when exposed to blue or UV light. EGFP is a variant of GFP that exhibits higher-intensity fluorescence when compared to GFP. Thus, the main difference between GFP and EGFP is the intensity of the green fluorescence each protein emit.

Reference:

1. Arpino, James A. J., et al. “Crystal Structure of Enhanced Green Fluorescent Protein to 1.35 Å Resolution Reveals Alternative Conformations for Glu222.” PLOS Medicine, Public Library of Science, journals.plos.org/plosone/article?id=10.1371/journal.pone.0047132.

Image Courtesy:

1. “Gfp and fluorophore” By Raymond Keller (Raymond Keller (talk)), under auspices of Crystal Protein. – Own work (Public Domain) via Commons Wikimedia
2. “Fgams ppat egfp puncta” By Zhao A, Tsechansky M, Swaminathan J, Cook L, Ellington AD, et al. (2013) Transiently Transfected Purine Biosynthetic Enzymes Form Stress Bodies. PLoS ONE 8(2): e56203. doi:10.1371/journal.pone.0056203 (CC BY 3.0) via Commons Wikimedia

About the Author: Lakna

Lakna, a graduate in Molecular Biology & Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things


What is blue light? - Biology

Where Are You Exposed to Blue Light?

The largest source of blue light is sunlight. In addition, there are many other sources:

  • Fluorescent light
  • CFL (compact fluorescent light) bulbs
  • LED light
  • Flat screen LED televisions
  • Computer monitors, smart phones, and tablet screens

Blue light exposure you receive from screens is small compared to the amount of exposure from the sun. And yet, there is concern over the long-term effects of screen exposure because of the close proximity of the screens and the length of time spent looking at them. According to a recent NEI-funded study, children’s eyes absorb more blue light than adults from digital device screens.

Blue light is needed for good health:

  • It boosts alertness, helps memory and cognitive function and elevates mood.
  • It regulates circadian rhythm – the body’s natural wake and sleep cycle. Exposure to blue light during daytime hours helps maintain a healthful circadian rhythm. Too much exposure to blue light late at night (through smart phones, tablets, and computers) can disturb the wake and sleep cycle, leading to problems sleeping and daytime tiredness.
  • Not enough exposure to sunlight in children could affect the growth and development of the eyes and vision. Early studies show a deficiency in blue light exposure could contribute to the recent increase in myopia/nearsightedness.

How Does Blue Light Affect the Eyes?

Almost all visible blue light passes through the cornea and lens and reaches the retina. This light may affect vision and could prematurely age the eyes. Early research shows that too much exposure to blue light could lead to:

parts of the eye

Digital eyestrain: Blue light from computer screens and digital devices can decrease contrast leading to digital eyestrain. Fatigue, dry eyes, bad lighting, or how you sit in front of the computer can cause eyestrain. Symptoms of eyestrain include sore or irritated eyes and difficulty focusing.

Retina damage: Studies suggest that continued exposure to blue light over time could lead to damaged retinal cells. This can cause vision problems like age-related macular degeneration.

What Can You Do to Protect Your Eyes from Blue Light?

If constant exposure to blue light from smart phones, tablets, and computer screens is an issue, there are a few ways to decrease exposure to blue light:

Screen time: Try to decrease the amount of time spent in front of these screens and/or take frequent breaks to give your eyes a rest.

Filters: Screen filters are available for smart phones, tablets, and computer screens. They decrease the amount of blue light given off from these devices that could reach the retina in our eyes.

Computer glasses: Computer glasses with yellow-tinted lenses that block blue light can help ease computer digital eye strain by increasing contrast.

Anti-reflective lenses: Anti-reflective lenses reduce glare and increase contrast and also block blue light from the sun and digital devices.

Intraocular lens (IOL): After cataract surgery, the cloudy lens will be replaced with an intraocular lens (IOL). The lens naturally protects the eye from almost all ultraviolet light and some blue light. There are types of IOL that can protect the eye and retina from blue light.

Talk to an eye care professional about options about ways to protect your family and your eyes from blue light.


Light Filtration

Most light sources emit a broad range of wavelengths that cover the entire visible light spectrum. In many instances, however, it is desirable to produce light that has a restricted wavelength spectrum. This can be easily accomplished through the use of specialized filters that transmit some wavelengths and selectively absorb or reflect unwanted wavelengths.

Color filters are usually constructed using transparent pieces of dyed glass, plastic, lacquered gelatin (e.g. Wratten filters) that have been treated to selectively transmit the desired wavelengths while restricting others. The two most common types of filters in use today are absorption filters that absorb unwanted wavelengths and interference filters that remove selected wavelengths by internal destructive interference and reflection. In any filter, a small amount of the incident light is reflected from the surface regardless of the filter construction and a small portion of the light is also absorbed. However, these artifacts are usually very minimal and do not interfere with the primary function of the filter.

Absorption Filters - These filters are generally constructed of dyed glass, lacquered gelatin, or synthetic polymers (plastics) and have a wide range of applications. They are used to create special effects in a number of photography applications and are widely employed in the cinema industry. In addition, absorption filters are commonly found in signs and traffic signals and as directional signals on automobiles, boats, and airplanes. The diagram below (Figure 1) illustrates a magenta filter that is designed to adapt to a camera lens. We have also constructed an interactive Java tutorial that describes how lacquered gelatin and glass filters work.

In Figure 1, the three incident waves are colored red, green, and blue but are intended to represent all the colors that comprise white light. The filter selectively transmits the red and blue portions of the incident white light spectrum, but absorbs most of the green wavelengths. As discussed in our section on primary colors, the color magenta is obtained by subtracting green from white light. The light-modulating properties of a typical color filter are illustrated in Figure 2. In this case we are examining a color correction filter that adds a factor of 50 color compensating (cc) units to incident light. The details of color correction filters will be discussed in the color correction section below.

In Figure 2 above, absorption is plotted against the visible wavelengths that are passed through the magenta filter. The peak intensity of absorbed light falls at about 550 nanometers, right in the center of the green region of visible wavelengths. The filter also absorbs some light in the blue and red regions, indicating this filter is not perfect and a small portion of all wavelengths do not pass through. A perfect filter would have a very sharp peak centered in the green region that trailed off to zero absorption at non-green wavelengths, but this is all but impossible to accomplish with real-world visible absorption filters that can be manufactured at reasonable prices. This type of unwanted absorption is often termed secondary absorption and is common to most filters.

Absorption Filters

Explore how gelatin and glass absorption filters are used to pass a specific band of wavelengths.

Interference Filters - These filters differ from absorption filters in the fact that they reflect and destructively interfere with unwanted wavelengths as opposed to absorbing them. The term dichroic arises from the fact that the filter appears one color under illumination with transmitted light and another with reflected light. In the case of the magenta dichroic filter illustrated below in Figure 3, green light is reflected from the face of the filter and magenta light is transmitted from the other side of the filter.

Dichroic filters are manufactured using multi-layered thin film coatings that are deposited onto optical-grade glass using vacuum deposition. These filters have four basic design types: short wavelength pass, long wavelength pass, bandpass and notch filters. Dichroic filters are far more accurate and efficient in their ability to block unwanted wavelengths when compared to gel and glass absorption filters. Short and long wavelength pass dichroic filters act as the names imply and allow transmission of only narrow bands of short or long wavelengths, reflecting the unwanted wavelengths. Bandpass dichroic filters are the most common and are designed to transmit selected wavelengths in the visible region. The diagram below (Figure 4) illustrates the transmission spectrum of a typical bandpass dichroic filter.

In this graph we have plotted the wavelengths that are transmitted by the filter versus the percentage of transmission. Note that the wavelength maximum is at 550 nanometers--right in the center of the green region. This filter is much more effective than the glass or lacquered gel magenta filter discussed above because there is virtually no passage of unwanted wavelengths and secondary transmission is almost nonexistent. The final type of dichroic filters are known as notch wavelength filters, which operate by "notching out" or eliminating unwanted wavelengths. Notch filters are effectively the opposite of bandpass dichroic filters. To use the example illustrated in the plot, a notch filter would pass the red and blue color wavelengths that are blocked with the bandpass filter.

Dichroic filters are commonly used for a number of applications including specialized filtration for optical microscopy and photography. High-quality color enlargers employ dichroic filters (instead of absorption filters) to finely tune the color of light that is passed through the color negative or transparency. This allows the photographer a high degree of color correction control over photographic prints.

Color Correction - Photographers and microscopists often must make slight corrections in the color of the illumination in photographic enlargers and microscope optical paths to insure accurate color rendition. This is usually done with Kodak Color Compensation (abbreviated CC) filters that can be placed in the light path of the enlarger or microscope. Although we refer to the Kodak filters here, there are a wide variety of manufacturers that produce these filters made with dyed gels or dichroic glass. These filters are labeled with a number that corresponds to the filter's light-absorbing ability, typically in the somewhat arbitrary range of 05, 10, 20, 30, 40, and 50 as illustrated in the table below for cyan filters.

Filter
Designation
Light
Transmitted
Approximate
Transmission
Peak Filter
Density
05 (CC05C)8.9
units
89%0.05
10 (CC10C)7.9
units
79%0.10
20 (CC20C)6.3
units
63%0.20
30 (CC30C)5
units
50%0.30
40 (CC40C)4
units
40%0.40
50 (CC50C)3.2
units
32%0.50
Table 1

As the numbers increase, more light is absorbed because the filters are increasingly darker. In the example above, a cyan filter range from 05 to 50 is featured where the background color for the table corresponds to the approximate filter color. The 30 cyan filter (referred to as a CC50C (cyan) filter) reduces the intensity of the complementary color by 50% or one exposure step (f-stop). The CC filters are available as Wratten filters (sized at 2" × 2" or 3" × 3") in 6 different colors: blue, yellow, green, magenta, cyan and red and in several densities (as illustrated in Tables 1 and 2). The easiest way to remember their use is to consult the "color compensating triangle", shown in Figure 5 below.

Just follow the arrows from vertex to opposite side or from side to opposite vertex. You can also refer to Table 2 for the correct CC filter color. For example, a green cast is removed by use of a CC magenta filter. The appropriate density of the chosen CC filter has to be determined by test exposures. See John Delly's "Photography Through The Microscope" for color illustrations of color casts.

Color to be
reduced
Color
compensating
Filter
required
BlueYellowCCY
CyanRedCCR
GreenMagentaCCM
YellowBlueCCB
RedCyanCCC
MagentaGreenCCG
Table 2

When conducting experiments involving photomicrography (photography through the microscope) we often add color compensating filters into the light path. This is most easily accomplished by shaping the filter into a circle with scissors and inserting into the light path just behind the diffusion filter. Alternatively, Kodak sells small metal frames that hold Wratten filters which can be placed on the light port of the microscope just above the field diaphragm. This allows for a global color correction in the resulting photomicrographs.

Contributing Authors

Mortimer Abramowitz - Olympus America, Inc., Two Corporate Center Drive., Melville, New York, 11747.

Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.


Light intensity varies depending on the lamp source and there are specific high and low light intensity fixtures, lamps, and bulbs. For example, high intensity discharge lamps emit a high light intensity, while fluorescent lamps are considered a “cool” or low intensity light source.

Different light intensities have specific uses when it comes to horticulture. For example, young plants require cooler light intensities than vegetative and blooming plants. In addition, indoor growing requires a higher intensity of light in general, because, unlike a greenhouse, there isn’t any natural light source coming in, and the intensity of the lamp(s) has to compensate for that.

Meanwhile, lower light intensity is more desirable when artificial lighting is not the primary lighting source.


What Gives the Morpho Butterfly Its Magnificent Blue?

There are more than 140,000 species of butterflies and moths in the world, fluttering on every continent except Antarctica. Their wings contain countless patterns and colors, providing critical tools for camouflage, finding mates and scaring off predators.

A Bay Area professor is trying to learn more about how those colors develop and evolve &ndash by going very, very small.

Nipam Patel, a professor in the Molecular & Cell Biology Department at the University of California, Berkeley, studies the thousands of tiny cells, known as scales, on butterflies&rsquo wings.

From a distance, the rows and rows of scales look like vivid patterns that decorate a butterfly's wings. But up close, each scale is like a dab of paint in a Pointillist painting or a tile in a mosaic they represent an individual unit of color.

Lepidoptera, the name of the order that encompasses butterflies and moths, translates to "scaly wings" -- as seen here on the wing of Morpho peleides. (Nipam Patel / UC Berkeley)

"Each scale is. a single cell, and as far as cells go, they are huge, much larger than the typical cells in our bodies," says Patel, who also works in Berkeley&rsquos Integrative Biology Department. "A human blood cell is about 10 microns in size -- a pretty typical size for a cell in our bodies. A butterfly scale is. a huge one, about 50 microns across and 200-250 microns long."

Morpho peleides scale image (15kx) taken with a scanning electron microscope. (Ryan Null / UC Berkeley)

Some butterfly scales are colored by pigments. But others rely on something called &ldquostructural color&rdquo -&ndash the production of color by nano-sized elaborate shapes that reflect and bend light. Structural color is why we perceive the Morpho butterfly, a dazzling type of blue butterfly found in South America, Mexico and Central America, as bright blue, along with peacock feathers, iridescent beetles and blue eyes.

"Blue is one the rarest colors made as a pigment," notes Ryan Null, a graduate student in Patel's lab. "Most animals can't produce blue pigments."

Varying species of Morpho butterflies. (Jenny Oh/KQED)

One area of ongoing research in the lab centers on structural color in butterflies as it relates to evolutionary developmental biology. The researchers are working to understand how nanostructures in butterflies&rsquo wings are built during the third stage of a their life cycle, known as pupal development. Patel and Null wanted to observe how structural color takes shape on the wings.

Because this normally occurs inside a Morpho's opaque pupa and isn't visible, they remove wings from pupae, grow them in a Petri dish, then study the process. Like developing a photograph or brushing paint on a blank canvas, colors and patterns slowly appear on the ghostly white wings over time &ndash as shown in short time-lapse movies they've filmed of several different butterfly species.

http://www.youtube.com/watch?v=ZJEw79Eafck
Ridges on the scales&rsquo surface are a key component that affects how the wing refracts light. (Video courtesy of Nipam Patel / UC Berkeley)

The scientists, who use high-powered microscopes to study their subjects, hope that by focusing on the very tiny, their research could be applied in innovative ways in the future.

"What's cool about this work is that in contrast to the way people currently mimic naturally occurring structural colors -- by using industrial processes deposit layers of heavy metals by electricity that's expensive and energy-intensive -- butterflies and moths have evolved a way to create these stunning colors with a string of sugar molecules," says Null.

"They appear to be the basic components of all animal cells. The genetic program controlling the creation of the nanostructures is elegant, robust and done in a way that is not hazardous to the life of the animal. If we can figure out how the butterflies do what they do, we have the potential to apply what we learn to a vast array of problems like creating cars that have their "paint" grown from the surface of their sheet metal, vivid cosmetics that are inherently safe for use with minimal testing, and even making solar cells more efficient."

Morpho rhetenor from Nipam Patel's specimen collection. (Jenny Oh/KQED)