Study Guide

Animal Systems In the Real World

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  • Health

    Whenever you come down with a nasty case of the sniffles, people are more than willing to offer their favorite in a whole slew of remedies, like sticking your head over boiling water or drinking water through a paper towel. But the one that everyone's heard of is the classic bowl of chicken noodle soup. Is it an old wives' tale or is there some nugget of truth to the age-old adage? The idea that chicken soup can fix what ails you is nothing new, and probably dates back to the 12th century or earlier. For an idea to stick around so long, there's got to be something to it, right?

    If you sit down and think about potential therapeutic advantages to chicken noodle soup, you might recognize some obvious things that would help your cold. A hearty bowl of soup will improve nutrition and hydration. Perhaps that's why it helps our colds. Or maybe it's simply a placebo effect—if enough people tell you that chicken noodle soup can treat a cold, you start to believe them. The power of your own positive thinking can actually lead to some therapeutic benefits.

    Chicken Soup. There's no cure like a bowl of piping hot chicken noodle soup.

    All of these reasons may be true, but none seems particularly compelling. We can find nutrition and hydration from lots of different sources, whether it be split pea soup, orange juice, or a thirst-quenching Gatorade. And there's nothing about the placebo effect that says it has to be applied to chicken noodle soup.

    In fact, one scientific study suggests there might be actual bona fide proof behind the health benefits of Grandma's chicken noodle soup. 

    What exactly happens to the immune system during a cold or other upper respiratory infection? A type of virus called rhinovirus usually causes these infections, and the innate immune system responds by sending white blood cells called "neutrophils" to the infection site. The movement of these neutrophils to the infection site is called chemotaxis. It's a pretty snazzy name, but we do have to wonder whether that mode of transportation is tough to hail in Times Square.

    When neutrophils attach to the epithelial layer of the lungs, they contribute to inflammation. Remember, inflammation means increased blood flow and warmth, which are part of the immune system's arsenal for fighting invaders. But inflammation also carries some not so fun side effects, which is why we feel the cruddy feelings. Thank goodness for daytime television, or we aren't sure how we'd survive.

    We know, we know: what about the chicken noodle soup? Well, a group of scientists in Omaha slaved away in both the kitchen and laboratory and found that Grandma's chicken noodle soup decreases neutrophil chemotaxis migration.

    Still prefer English? Simply put, a piping hot bowl of soup might decrease how many neutrophils show up to fight the virus, which in turn reduces the inflammation. Less inflammation means less symptoms and yucky feelings. This study wasn't conducted in humans, but it still does suggest that the adage for chicken soup to cure a common cold has at least something going for it.

    Now, there's nothing to say some other group of enterprising (or hungry) scientists may find some other reason why chicken noodle soup always seems to hit the spot when you're battling a stuffy nose. But for now, it looks like Grandma might have some scientific knowhow to back up her good intentions when she hits the kitchen.

  • Research

    Many years ago scientists realized that the same antibodies produced by B cells that normally fight off a cold could advance medical research. So they set off to design and produce antibodies that sought out particular proteins in the body (perhaps some that were a part of a neuronal receptor).

    Making antibodies is complicated and time consuming, so we aren't going to belabor the details here. Just to give you the basics, research antibodies are made by "immunizing" an animal with a particular antigen. Scientists inject the antigen into a lab mouse, and its own immune system launches an attack. The mouse's B cells make lots of antibodies that react to that particular antigen. Scientists can then snag those antibodies, isolating them from the rest of the stuff inside a mouse, and add them to a piece of bodily tissue. These newly synthesized antibodies then bind to that particular protein the scientists had in mind.

    In the lab, scientists use antibodies in a technique called immunohistochemistry to visualize particular proteins. Each antibody is developed to recognize a particular protein, and when these same antibodies are attached to a fluorescent tag, scientists can see where the protein hangs out in a particular tissue—just look for the glowing parts. Essentially, when the fluorescent tags are excited with specific wavelengths of light, they glow.

    Scientists have been able to take some amazing pictures of the body this way. But not only do these pictures look totally awesome, this immunohistochemistry technique has expanded our knowledge of how the body works.

    The cool part about all of this is how research has used antibodies to help treat diseases. Take cancer for example. Chemotherapy, a common type of cancer treatment, has all sorts of nasty side effects. Patients lose their hair, they lose weight, and their immune system suffers because the treatment hits all cells, both cancerous and not. The idea is that if researchers are able to locate particular cancer cells, cancer therapy could be more direct, and a patient would experience fewer side effects as we reduce the number of healthy cells caught in the chemo crossfire.

    Different types of cancer cells express different types of surface proteins and/or antigens, so researchers use this characteristic to their advantage to create antibodies that recognized a specific cancer cell antigen. When they inject these antibodies into animals, the antibodies seek out the cancer cells and destroy them. To provide cancer therapy, scientists use these antibodies in different ways.

    First, they let the antibodies point out the cancer cell to the patient's immune system, and let it attack those cells specifically. It took years to develop this technique, but it is extremely useful in treating lymphoma. Because lymphomas come from B cells, and all B cells express a particular protein called CD20, the antibodies target both healthy and non-healthy B cells. Once they "tag" these cells, the patient's own immune system can kick in to destroy all B cells.

    Since cancerous cells grow like crazy, blocking their ability to grow is another way to specifically fight those cells. Cancer cells express lots of growth factors and secrete growth signals to blood vessels to keep growing. Antibodies that are specifically on the lookout for these growth signals can help prevent the cancerous cells from growing, and cut off the cell's blood supply. Researchers used this technique to develop drugs that target different types of cancers, including colon cancer. 

    A more specific way to directly attack cancer cells is by attaching radioactive drugs to the antibody. So not only is the antibody hunting down cancer cells to call in reinforcements, but it's packing heat as well. Essentially, the antibody-tagged cancer cell receives a small dose of radiation for as long as the antibody remains attached. Since the antibody is attaching to cancer cells in particular, the radioactive particles are only bound to cancerous cells (and leave the healthy ones alone), which means the side effects from radiation are less severe. This is how a drug that's used to treat non-Hodgkin's lymphoma works.

    Antibodies have helped scientists treat other diseases too. They've been approved, in various forms, to treat cardiovascular diseases, transplant rejection, and multiple sclerosis. It's amazing what we've been able to get these antibodies to do.

  • Environment

    Pheromones are another type of chemical that sends out signals. The key difference with pheromones is that those messages are sent outside the body as a way to communicate with others of the same species. (Keep in mind that they are fundamentally different than hormones since hormones act within the body, but their main purpose is the same: communication.) 

    Although lots of animals emit pheromones to communicate territory or reproductive behaviors, the most advanced pheromone system belongs to tiny honey bees. The most complex pheromone is the Queen Retinue Pheromone from queen bees. 

    Honey bees use pheromones to communicate all sorts of things: their attractiveness and desire to mate, their location, and the need to be on the defensive when there's an animal nearby. 

    Honey bee. If you aren't a queen bee, your life revolves around her.

    Before we get into any details about these pheromones and the hierarchical and royal society of bees, let's go over honey bees 101, in case you somehow missed out on bee science. First, there are three different kinds of bees: queens, drones, and worker bees. The queen is supreme, and her main goal in life is to make babies. Heck, she lays nearly 2000 eggs in a day. (She basically does nothing else.) Drones are male bees whose sole purpose in life is to mate with a queen—whether it's his queen or one from another colony. Mating is so important that once they've done the deed, drones go belly up and die. The worker bees are sterile female bees that do all the work: cleaning the hive, making the honey, doting on the queen bee. What a life.

    It's only when bees cover a larvae with a chemical called royal jelly that a queen is made. (So regal.) Unlike humans, these bees don't have to come from one royal family tree or another; they just need to get coated in that special jelly.

    Once she's born, this virgin queen fights with any older queen bees to take over the hive. Most young queens die before she gets to become a mom. If she happens to survive, she'll fly around hoping to mate with about 15 different drone bees. It's the drone's sweet kiss of death, since they drop like flies once they've inseminated their queen.

    The queen bee saves and stores all the sperm from this mating soiree since it's likely to be her last. She'll continue to lay fertilized eggs for the rest of her life. If she doesn't mate with enough drones and runs out of sperm, she'll lay unfertilized eggs that later become drones. 

    How do pheromones fit into this hierarchical society of honey bees? Queen bees actually produce a number of chemicals that are collectively known as Queen Retinue Pheromone (QRP). These chemicals are released from glands in her head and abdomen, and both attract mating drones and keep female worker bees sterile. That way she ensures that she's the only female able to make baby bees.

    If you are chemically savvy, or just have a weird passion for chemical compound names, try some of the QRP chemicals on for size: 9-oxodec-(E)-2-enoic acid, 9-hydroxydec-(E)-2-enoic acid, methyl para-hydroxybenzoate, and 2-(4-hydroxy-3-methoxyphenyl)ethanol. Who knows? Maybe it'll show up on your next spelling test.

    As long as the queen bee is healthy, life continues the same way: laying eggs day in and day out. But if her ovaries malfunction and aren't healthy anymore, she releases less QRP and the colony writes her off. They won't even hesitate at killing the royal bee once her baby-making capabilities have gone awry. The drones will mate with a new queen. Bee-making is serious business.

    Another cool part about these queen bee pheromones is that they let her colony know how well she mated. Essentially, if she mated with many drones, her pheromones attract more bees than if she didn't have too many takers. If there are two queen bees in a colony, the more promiscuous one wins and gets all the attention.

    There's no way to be quite sure, but this queen bee was probably pretty successful in that whole mating thing.

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