Why is there lutein in your vitamin pill
and what does that have to do with Drosophila vision?

William S. Stark
SLU Biology Department Seminar
http://starklab.slu.edu/Seminar2007.htm
Fall, 2007

Recent Biology seminars:
Microscopy of Drosophila's 6 rhodopsins, Fall, 2002
Vision in the Ultraviolet, Fall 2005

Funding (and conflict of interest disclosure)

Research
$350 Undergraduate Research Fund
College of Arts and Sciences
Neil Patel "The effect of zeaxanthin and other carotenoids in the health of Drosophila eyes"

Travel to Association for Research in Vision and Ophthalmology (ARVO) 2007 meeting
$2000 Dennis and Laura Gierhart (charitable giving account)
Grant ID 3676725

Background (Drosophila)

Fly food (the snotty term, Drosophila medium) usually contains yellow corn meal.

Serendipity, trying white corn meal, and using a retinoid free medium, started me on a lifelong interest in vitamin A deprivation and replacement. This picture shows Freeze fracture EM of rhabdomeric microvilli of vitamin A replete and deprived Drosophila
Harris, W.A., Ready, D.F., Lipson, E.D., Hudspeth, A.J. and Stark, W.S. Vitamin A deprivation and Drosophila photopigments. Nature, 1977, 266, 648-650.

Decades later:
I had worked out the visualization of all 6 Drosophila rhodopsins.
and
I had worked out GFP reporter for vitamin A induced rhodopsin gene transcription
Stark, W. S., Thomas, C. F. Microscopy of multiple visual receptor types in Drosophila, Molecular Vision, 2004, 2004; 10:943-955

Why is Lutein in your vitamin?

(that's a good question!)

Before she retired in 1990, Lynette Feeney-Burns gave me several of her photographs including this one of a monkey retina fed a chow rich in carotenoids. Note the yellow pigmentation, the macular pigments.

Beta-carotene is the best known carotenoid, a dimer of vitamin A. The macular pigments were first identified as lutein and zeaxanthin.

Many years ago, I met John Landrum, a chemist from Florida International University, and Richard Bone (second from left), a physicist from Florida International University. They gave me enough zeaxanthin and lutein for one study:

Stark, W.S., Schilly, D., Christianson, J.S., Bone, R.A. and Landrum,J.T. Photoreceptor specific efficiencies of beta-carotene, zeaxanthin and lutein for photopigment formation deduced from receptor mutant Drosophila melanogaster.Journal of Comparative Physiology, 1990, 166, 429-436.

But that is beside the point.

They did psychophysical studies addressed to the macular pigments and were the first to identify the macular pigments as lutein and zeaxanthin. Eventually, in a bold experiment, they ate large amounts and showed, by studying their own vision, that their macular pigments increased.

Their work was far more elegant than mine, but I already have mine on my web site, so I'll use mine (1987) to give you an idea: A subject reports what he sees, and the difference between photopic spectral sensitivities on and off of fovea are due mainly to absorbance by macular pigments.

Photopic sensitivities to ultraviolet and visible wavelengths and the effects of the macular pigments in human aphakic observers. Current Eye Research, 1987, 6, 631-638.

By then, numerous studies had suggested that
(1) blue light damaged photoreceptors
(2) macular pigments decreased blue light to foveal cones
and
(3) these were the receptors lost in AMD (age-related macular degeneration)

It was soon after I saw their study that I started to notice that lutein was in vitamins.

The chromophore of Drosophila rhodopsin

Take a look again at the carotenoids.

Beta carotene is a dimer of vitamin A, retinol. The aldehyde, retinal, is the chromophore of most vertebrate rhodopsins (some fish rhodopsins are based on vitamin A2, dehydroretinol). Many insect rhodopsins are based on 3-hydroxyretinol. Zeaxanthin is a dimer of the 3-hydroxylated chromophore, and lutein is a dimer half of which is this chromophore.

Going beyond my laboratory's previous studies, we used these carotenoids in the diet

(1) as precursors of the visual pigment's chromophore.
and
(2) to assay for activation of opsin's promoter

For 10 years, I have been going to this dinner at the ARVO (Association for Research in Vision and Ophthalmology). As you see, it is called the "Macula and nutrition group," but my first invitation referred to "investigators and students interested in the role of carotenoids in the eye." You'll be happy to note that there are many carotenoids in the food served. Also, noting that these pix are on my server, I am obviously the self-appointed photo-journalist for the event.

Here I met Wolfgang Schalch (left) of a company (formerly Roche, now DSM "don't spend money"), and, after the appropriate Material Transfer Agreement, they gave me enough zeaxanthin and lutein for one study:

Stark, W. S. Effects of lutein and zeaxanthin as chromophore precursors and in regulating opsin gene expression in Drosophila. Association for Research in Vision and Ophthalmology, 2006, Fort Lauderdale, FL (*Investigative Ophthalmology and Visual Science, 2006, 47).

Here is Dennis Gierhart (left), Chairman and Chief Scientific Officer of ZeaVision. I've only known him for a few years, amazingly, since his company is here in St. Louis and markets a nutritional supplement, EyePromise. The formula indicates that zeaxanthin. as well as lutein, is included.

Here are containers and smears.

Here is Mark Sankoorikal, an undergraduate who worked in my lab on the zeaxanthin-EyePromise project. He's not always dressed like this, but I'm now on the premed (oh, bite my tongue, pre health professional) committee and have access to such embarrassing photos (and I always threaten people with putting embarrassing pix on the internet). And, while I'm on a roll, here is one of his partners in crime, Samir Sharma. Also Nilay Patel worked on this.

Enough family photos, here's some data they obtained:

This photo shows that EyePromise serves as a precursor for R1-6 rhodopsin and that it also activates the promoter of the gene for R7's rhodopsin.
This photograph is a better demonstration that EyePromise serves as a precursor for R1-6 rhodopsin.

Where do we go? (human studies)

People cherish their eyesight; understanding the causes and prevention of blindness is so important for the quality of life -- I use this site of one of many possible links to state that a lot of funding (public and private), information and publications, and marketing center around preventing loss of vision.

Follow this reasoning:

(1) Many studies, including my own my own, suggest that blue and ultraviolet light is especially damaging to photoreceptors.

(2) Many studies, including my own, demonsrtrate that macular pigments block blue light to foveal cones.

(3) Many studies, starting with those of Bone and Landrum, show that diet can increase macular pigment optical density (MPOD)

(4) Foveal cone-mediated vision is lost in age-related macular degeneration (AMD)

Thus, testing MPOD is useful

My eye doctor (oh, bite my tongue, eye care professional), Dr. Susan Yang, is also the eye doctor of a few other people in this department. She, and her family, are close friends. So she did me the favor of carefully doing the refraction on my aphakic eye.

Here is a self-portrait, looking even goofier than ever (even goofier than my premed students), but hey, at least I still have both ears. The minus correction for my right eye is for myopia. The strong plus correction for the left eye is because I had cataract surgery in 1959. Since the lens blocks UV, human UV vision has always been one of my interests, one topic in my last seminar.

The life expectancy after cataract surgery is about 5 years since most people get surgery when they are old. Also, most people get intraocular lens implants that block UV. My retina is uniquely useful for study, exposed to UV for 48 years so far. The conventional wisdom is that UV is damaging.

Here is "quantifeye," a clinical psychophysical apparatus marketed for ophthalmologists and optometrists to quantify patient's macular pigments. They get a reading of 0.43 (optical density) for my right eye, much lower for my left eye.

Is that because of poor vision or low macular pigment optical density?

Before I explain my method for demonstrating to subjects whether they have healthy macular pigments, here's a reminder of what everybody (hopefully) learned about polarized light.

I posted this picture of macular pigments on my BIOL 347 (General physiology lab) site in conjunction with a demonstration for students of Haidinger's brushes. The optics are shown here. I see Haidinger's brushes clearly with both eyes.

Here's Maxwell's spot. Stare at the green. Then you'll se a dot in the middle of the blue.

There are thus several qualitative assays that do not rely on visual acuity. These could be refined into quantitative tests.

Am I losing macular pigments? Am I losing eyesight? If so, is it because I lack UV protection from the lens? Or because I lack macular pigments? Or both? These optics, shown here, can also be used to study sensitivity.

This page was last updated 9/6/07

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