Monday, March 28, 2016

merely a pigment of the imagination – part 1

European Starling
I recently was asked to design some birds for a mural here in Shreveport to be painted by the public. I got to pick which birds, and made my list of Passerines that are local, attractive, colorful, recognizable, and easily translatable to paint-by-numbers. I was zooming through the designs, recommending Pantones with excitement until I crashed into a little brick wall called the European Starling.

People are attracted to bright colors. Butterflies, beetles, amphibians, and of course birds bear colors that span from Roy to G. Biv. You and I are sadly not as colorful (though current trends on Pinterest are trying their hardest to change that – somebody stop the madness).  We're all pretty much shades of brown and blacks, and when lined up on a spectrum, really don't show that much variation from one person to the next.

So melanin-y. (Wikipedia)
We’re colored primarily via pigments called melanins. Our two primary types of melanins are eumelanin (blacks and browns) and pheomelanin (reddish browns). The infinite combinations of quantities of eumelanins and pheomaelanins comprise the spectrum of human coloration, spanning from skin to hair to eye color and characterize mammalian coloration. Birds also utilize melanins, as is finely exemplified by the Red-tailed Hawk to the right.

Reds, oranges, and yellows also are results of pigments. Carotenoids are the family of pigments that give animals these beautiful fire colors and, as a rule, cannot be manufactured by animals’ cells. Instead, they have to acquire them from the environment via diet. Cue back to the amazing story about Cedar Waxwing’s tail tips turning orange due to the consumption of both yellow and red honeysuckle berries, and flamingos being pink dependent on their consumption of crustaceans in their shallow wading pools.

Though not as common, another coloration mechanism exists in birds. Pigments called porphyrins are identifiable by their fluorescence when exposed to ultraviolet light. Unlike melanins or carotenoids, which are lipids (fats), porphyrins are modified amino acids and can reflect back greens, brilliant reds, pinks and even browns when exposed to white light. In fact, I noticed a few years back when working with a Barred Owl that it had a soft pink tinge to the underside of its wings. After some research, I discovered that that pink tinge was due to the presence of porphyrins in owl plumage. Had I shown a UV light on that owl, it would have lit up like a Christmas tree (read the paper here).

So what about blues? Where do they come from? And why couldn’t I draw that European Starling? These questions lead us into a whole different box of cookies called structural coloration – a mechanism of producing color without a pigment. Blue, and the colors of an iridescent surface like a European Starling, do not exist as physical entities within feathers. No molecule or "thing" exists within feathers that is actually blue-colored or iridescent-colored. In fact, one might say such colors are merely pigments of the imagination...

Hold your bated breath. Part two on structural coloration headed your way.

TEASER. (Wikipedia)

Wednesday, March 23, 2016

wham bam thank you ma'am

Summer of 2008 was one of my best yet. It was filled with early morning fishing trips, catching my first bass on a fly rod, southern home cooking and mowing the lawn using my dad’s 360 degree riding lawn mower. I can still smell that summer when I think about it – including a prominent olfactory memory of Calamine anti-itch lotion.

As the summer came to a close, my dad and I decided to plan a father-daughter hiking trip before I headed back to college. We started training by walking the neighborhood with our packs and slowly adding gallons of water each week to increase the weight. At the time, I thought he was trying to get in shape to keep up with me. Now, I see it was him who was worried about my then 95-lb little body trying to carry a whole pack for three days; and he was right to worry – it took me a few weeks to build up the stamina. Once August rolled around, we were ready and headed up to a wilderness area in Arkansas with only our packs in the bed of the truck.

We spent most of the first day hiking down, and took our first break at a stream. I sat on a log wearing a gray shirt tee shirt and my trusty khaki shorts. Once we rested up we began hiking up. And up. And up. We took another break and I sat down another log to chug some water. We repeated this several times until light started to get dim, we found an area to set up camp. I ate dinner, also sitting on a log in my khaki shorts, and then we turned in.

The bugs were deafening that night. I don’t think either one of us got any sleep. You’d think it would be silent in the middle of a wilderness area at night, but not in Arkansas and not in the middle of the summer. I remember asking myself, as I tossed in my tiny hot tent that night, if I should be worried about any of the bugs.

The next day was more of the same, until about halfway through the day I began to hurt… and itch. And burn. My under-butt region and the tops of my thighs began to itch past the limits of what I thought was humanly possible. A quick trip behind a tree and a peek at my behind revealed to me that my butt had turned red. So red that the individual bites were indiscernible until closer inspection. Chiggers – how had I not thought to beware the chiggers in my little khaki shorts?

Redbugs, or chiggers as we call them in the South, are not actually bugs. They’re arachnids, like spiders and scorpions and belong to the genus Trombicula. They’re a type of mite barely big enough to see with the naked eye when they’re adults and are cute little vegetarians that eat plants. But the babies, well, let me tell you about the babies.

Larval redbugs feed on skin. They like to find tight, protected spots like YOUR PANTIES or fat folds to burrow into your skin and secrete enzymes that start to digest it. And then they slurp it up. The slurping and chewing causes extreme irritation and itching to their hosts. They’ll stay attached for up to five days, and then drop off of your body like you never meant anything to them at all. They don’t even take you out for breakfast the next morning – wham bam thank you ma’am.

Upon returning home from our hiking trip, I counted 110 chigger bites on my butt and upper thighs, and an additional 70 or so elsewhere. I’m sure I was not my usual frickin delightful self for those few days as I lamented wearing my loose-fitting shorts and sitting on so many chigger-infested logs like a dope. I had to take Tylenol PM to sleep at night for a week.

Despite their panty fetishes, chiggers really are pretty non-invasive parasites. They don’t suck blood and don’t enter your body past your superficial layer of skin. Parasites can get so much worse than little baby redbugs munching on some skin cells. Still, if you're not a southerner and find yourself in our neck of the woods during the summer, take precautions. No one deserves to be used like that.

Monday, March 21, 2016

tiny lab monkeys but without the guilt

The husband of a dear friend (hi MK and Andy!) recently challenged me to incorporate a fruit fly into an illustration. Obviously, I made a hipster fruit fly logo because that’s what everyone has been missing in their lives. A few folks asked me what the G, T, C, and A meant in the illustration – so, here it is.

Drosophila melanogaster is a species of fruit fly that has been used as a model organism in labs for about a hundred years, like tiny lab monkeys but without the guilt. In 1909, an entomologist named Charles Woodworth suggested they be used to study genetics, kind of like Gregor Mendel used pea plants. Woodworth’s idea was brilliant.

Drosophila are sexually dimorphic, meaning it’s easy to tell males from females by appearance. This is useful when it comes time to mate them. Secondly, they have only four chromosomes, which are easily observed during times of genetic activity. They have several discreet physical traits that are genetically determined, like eye color, wing shape, bristles, and body color. They breed quickly and a lot- allowing people to observe multiple generations in a reasonable amount of time. Lastly, they’re easy and cheap to maintain. They’re frickin fruit flies.

For decades people have been studying these guys. They’ve given us insight into how basic genetics, beyond the white or red pea plant blooms, operate in a system founded on DNA. In 2000, we completed sequencing the entire genome of Drosophila melanogaster- that is, the sequence of 139,500,000 G’s, C’s, T’s, and A’s that make a fruit fly a fruit fly.

Not only can you look up every single nitrogenous base (G, C, T, or A) present in a red-eyed, black-bodied, curly-winged, bristleless fruit fly, you can look up where those genes reside, what sequences control them, and what bits of DNA don’t do anything.

One might ask what good it does to have such an intimate genetic knowledge of a fruit fly, and one might be totally justified in asking that question. The answer is this: 75% of known human genes that cause disease are present in the fruit fly’s genome. About 50% of their coding DNA also codes in us. By studying the fruit fly’s genome, we’re studying how things like diabetes and cancer work. And that’s important.

So if you haven’t hugged a fruit fly today… don’t. They smell weird. But do tell it thank you for its service to science.