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What Is Chemotaxis?

Two unicellular organisms.
Researchers who work in microbiology labs may study chemotaxis.
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  • Written By: Mary McMahon
  • Edited By: Nancy Fann-Im
  • Last Modified Date: 20 August 2014
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There is enough iron in the human body to make a nail.  more...

September 22 ,  1862 :  US President Abraham Lincoln announced his preliminary Emancipation Proclamation.  more...

Chemotaxis is movement of small organisms and single cells in response to chemical signals in the surrounding environment. This plays a role in a number of biological processes, from fertilization to fighting infections. Research on chemotaxis includes exploration into how small organisms move, when they respond to chemical signals, and what can interrupt these processes. Researchers work in microbiology labs with access to high-resolution microscopy and other tools for studying processes that occur on a very minute level.

In chemotaxis, individual cells, unicellular organisms, and small multicellular organisms respond to chemicals by moving closer or further away from them. They have receptors sensitive to particular chemicals of interest or concern so they can respond to them, using a variety of techniques for movement. Chemoattractants are chemicals that tend to increase the desire to approach a given chemical source, while chemorepellants encourage organisms or cells to move in the opposite direction.

Sexual reproduction relies on chemotaxis to allow sperm to migrate toward an egg, following chemoattractants produced by the egg so it can complete fertilization. During fetal development, chemotaxis also plays a role in the movement of cells as the organism develops; budding nerve cells, for example, start to distribute themselves to map out the nervous system. Errors in this process can result in birth defects or miscarriages, if the growing fetus develops abnormalities incompatible with life.

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The immune system uses cells like neutrophils and macrophages to detect infectious organisms and neutralize them, relying on chemotaxis to sniff out chemicals produced by these cells so it can track them down. Conversely, microorganisms can respond to chemorepellants in toxins to avoid them, drifting further away from the chemicals until they reach a safe zone. These two examples show how the process is used by individual cells as well as complete organisms to navigate their environment, relying on chemical signals to decide how, when, and where to move.

Chemicals can interrupt chemotaxis by confusing or disorienting cells, leading them to make mistakes. If cell motility is limited by environmental factors, this can also result in errors where organisms may move away from sources of nutrition or closer to toxins. Problems with cell migration can also develop in situations like nerve injuries, where the growing new cells attempting to replace damaged older cells may grow in the wrong direction due to orientation mistakes. Researchers have an interest in learning more about these processes, as they can be important for treating injuries and disease as well as addressing infertility.

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irontoenail
Post 3

If you need to see chemotaxis in action, there are some pretty good videos online. I've seen one with examples of neutrophil chemotaxis.

I mean, it doesn't really look like much, it's just a cell moving in a particular direction.

It's interesting to think that this happens every time you injure yourself though, as the neutrophils race towards the site to help prevent infection.

But, anyway, if you need to see the cells in action for a class or something, there are a wide range of videos available.

KoiwiGal
Post 2

@croydon - Damage can affect the movement of sperm but there might be other factors as well. disrupting chemicals present in the womb, for example which make the sperm think they should move away from the egg.

In fact, I've thought that that might be a good form of birth control. If they could come up with a method of inserting or producing a chemical which makes the sperm move away from the egg, that could be very non-intrusive, easy way of preventing pregnancy through chemotaxis. The definition of a morning after pill is one that you can use after you've had sex that prevents pregnancy, but often people object to the fact that the sperm and the egg have fused, even if they don't attach to the womb wall.

If you could prevent the fusing by this method, you've stopped the process they object to altogether.

And it could be used before sex as well, although I think that it wouldn't be as reliable as barrier methods or the pill.

croydon
Post 1

It's so interesting that something as simple as a sperm cell is able to navigate towards an egg. I've always thought it was more that there were so many of them that some of them were lucky enough to stumble into the right direction, but they actually follow a chemical signal.

It's no wonder they are so worried about fertility lately, as I've heard that often sperm seem to have become confused and swim in circles instead of the direction they are supposed to go. I didn't realize what an issue this must be for couples who are trying to get pregnant until I read this article.

I suppose it would only take a little bit of damage to confuse sperm and I've heard even things like cell phones aren't all that good for them.

It makes you wonder if we are heading towards a science fiction scenario where people have to go to extreme lengths in order to get children.

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