One author is ScIU guest writer Melanie Chin, a graduate student in IU’s Department of Biology and Program in Neuroscience.
This post is part of a series featuring amazing science images and the stories behind them. Comment below with your guess and read on to see if you are correct!
There is no argument that the photo below is beautiful, but you might be surprised by what it is depicting. In fact, I might argue that this photo shows us something we encounter almost every day and, unfortunately, is thought of as far less magical and majestic. It is funny how a new perspective really does change our view!
First, this image depicts something that is symmetrical and quite colorful. You also might notice that there is a core, some bubbly wings, and something that looks like antennae. So, what is it? An ethereal butterfly?
Before spilling the unbelievable truth, I will first explain what you are seeing in this photo in greater detail. The colors in this image are used to describe the depth of the structures being depicted. In this particular image, blue and cool colors indicate that something is close to the surface, whereas warmer colors indicate deeper structures. The variety of colors in this image indicate that this is something with substantial volume, substance, and structural complexity!
One of these structural complexities is the colored blobs outlining the “wings” — they almost resemble little cells. In fact, that is exactly what they are! More specifically, they are glia, cells in the brain that are not neurons. Traditionally, it was thought to that glia were only present to provide structural support for neurons, like a scaffold; however, recent research shows that this is not the complete story. Now, it is well-established that while glial cells do provide support, they also have a wide array of other critical functions including: (1) maintaining the cellular chemical environment to keep neurons safe, (2) helping neurons conduct electrical signals, and (3) helping in injury recovery by removing harmful substances and repairing or removing dying cells. Due to the variety of purposes glia serve, it may not be surprising that the human nervous system is made up of billions of neurons, but approximately ten times more glial cells!
So, getting back to the image: it depicts a subset of glia in the Drosophila larval brain. The outlines of these circle-shaped glia are prominent and colorful because these cells have been “stained” to show us where a gene called No mechanoreceptor potential-C (nompC) is found.
nompC codes for a mechanosensitive ion channel — a protein that causes a chemical change in neurons when it senses a physical change. For example, when you grip your Starbucks cup, the mechanosensitive ion channels in the skin of your hand actually change shape in response to you touching the cup. In other words, you are physically changing these receptors by pressing the cup against your skin. This change in shape alerts neurons connected to these “activated” channels to send signals from your hand to your brain, telling your brain that you are holding an object.
In Drosophila (fruit fly) larvae, this protein has a role in maintaining coordination and gentle touch responses, which allow flies to sense something as soft as the touch of an eyelash. This image is the first evidence of its presence in the larval brain, suggesting that nompC may have an undiscovered role in detecting physical changes around the brain surface. You may be asking, why does a brain need to detect these physical changes?
This ability is important because physical changes in the brain could be anything from a mild bump to a high impact event, such as concussion, which arises from the brain being forced at high speeds into the inner surface of the skull — imagine shaking a clump of jello in a jar. The presence of the nompC receptor in the fly brain gives us a possible model to study traumatic brain injury, a very prevalent problem for humans today, in an experimental environment. In the Tracey Lab at IU, we use a simple device to deliver a consistent, high impact traumatic event to fruit flies. We then study the role of genes, including nompC, in this type of traumatic brain injury.
While nompC is not present in the human brain, there are many human proteins with similar properties. In fact, about 75% of human disease-causing genes have an equivalent gene in fruit flies, making them an excellent model to answer scientific questions in a simpler system. Specifically, flies breed quickly, have simple and well-understood DNA and nervous systems, and can be studied in large numbers with minimal ethical concerns compared to mammals, such as rodents or humans. A larger goal of the Tracey Lab is to understand the genetic basis of nociception, or the sensing of painful environmental stimuli. This type of work could lead to the discovery of novel targets for the therapeutic treatment of pain disorders.
This explanation is all to say that this is a picture of a brain — the brain of a larval stage fruit fly — that could provide insight into potential new roles for mechanosensitive ion channels in the fly brain and yours.