|Nope. This island does not represent your genes. (Source)|
What some people may not realize is that "environment" to a scientist talking about genetics may be something very different from "environment" to a non-scientist reading a news article. While a scientist may be vividly imagining a bustling microenvironment of native molecules in the way only scientists seem to do, the general reader may simply be thinking about "toxins" or "chemicals." That's why Double X Science is here to help with a primer on what those scientist types may mean when they talk about genes and environment. See how useful we are? Tell your friends! (Speaking of environmental influences... ).
Where does environment begin and end? Let's begin at the end
No gene is an island. Your genes consist in part of a special code that is really an instruction manual. Your cells rely on internal translators to decode these instructions and use them as a guide to make various proteins, the molecules that give your cells, tissues, organs, organ systems, and you much of their structure and function. Proteins do thousands of jobs, from breaking down food to building and replacing tissues (news release) to governing cell division. Most of your cells are engaged in making proteins, a complex, exquisitely regulated and multi-step process. But they don't do it in a vacuum.
That code the cell uses to build the protein? That instruction manual is susceptible to all kinds of interference. Pages get torn out or folded over or stuck together. The words of the code can be changed, sometimes subtly, sometimes unmistakably, and all kinds of factors can jumble up those words so that cell ends up making a protein that isn't quite what was intended. It's even possible to use the cellular version of Liquid Paper(TM) to mask the code so that the cell doesn't recognize its existence. Sometimes, these changes have no observable effect. Sometimes, they have big bad effects, such as disease, or helpful outcomes, such as disease resistance.
That code sits in a cell in a body (you) made of trillions of cells doing hundreds of different jobs, taking in things from the environment, playing host to millions of other organisms (themselves an environment), altering and shifting with every passing second as the whole system works to keep you together and functioning within certain acceptable limits for human life. All of these processes can influence the code, leading the cell to use it, change it, use only certain parts of it, Liquid Paper over it, tweak what results from its instructions, or just ignore it. It's impossible for any code in that situation to function in the total absence of influence from its environment, in part because the code itself is just the beginning. Much of the environment's influence is reflected in what the cell does with the instructions, not just what the instructions say.
This multitude of environmental influences is one reason that even people with identical genetic codes can have differences in diseases we think of as being largely genetic. No gene--no code--is an island. You are not your genes. You are your genes and your environment.
No nucleus is an island. Most of our genes are packaged neatly with the rest of our DNA around molecular spools inside a cellular vault called the nucleus. This vault is a choosy sentry, letting in only certain molecules carrying proper ID. Yet inside the nucleus, there is an environment. This environment is not "toxins" or "chemicals," the things that many people probably think of when someone says "environment" and talks about genes. But it is a busy place with its own milieu. Some parts of the code are in use, some sit quiet, and many molecules bustle and hustle to maintain, copy, process, or protect these important instructions. Every little bit of this hustle and bustle can influence some aspect of what happens to a code in the nucleus, interfering with or enhancing its use or resulting in accidental changes that may have big effects further down the line. The nucleus is the final stop in the chain of environmental influence, wherever that influence may originate.
No cell is an island. Outside of that vault is the big, wide world of the cell. The cell is the molecular version of a busy metropolis (see beautiful video, The Inner Life of the Cell, below), a complex system of cellular highways that the cell uses to deliver packages internally, take in deliveries from the outside world, and transfer the millions of molecules it's using and making to the right places at the right time. There's a generator, a recycling center, guards at the gate, and a protein production facility and processing plant, complete with a post office. And that cell sits in an environment, usually, of many many other cells, also busy with their duties. What happens outside of that cell affects the inside of the cell, altering traffic flows, protein production and packaging, signaling and delivery along the routes, and, ultimately, processes inside the vault called the nucleus, the final destination in the chain of environmental effects. From outside the cell, through the cell, and to the nucleus, every step along the way is one that environment can affect, all the way down to what the cell does with its genes--the codes--for the proteins it makes.
No tissue or organ is an island. A lot of cells working together to do the same thing in your body make up a tissue. Tissues combined together to perform a function are an organ. Let's take the organ named after living, the liver. It keeps you alive by filtering your blood and reconstructing substances that might harm your cells into less-harmful compounds. Just about everything you ingest gets passed through here. When the liver takes up something like ethanol, the alcohol we ingest at wine o' clock, and gets to work making it less awful for your body, guess what does that work? The cells that make up the liver. The liver's environment is their environment is each individual cell's environment, and eventually, the influence will pass to the nucleus, the final destination in the chain of environmental influence, where the code lies.
You are not an island. And whatever you encounter in this world may well influence you right down to the level of your genes. But while many people might think of "toxins" or "chemicals" when they think of environmental influences on genes, your chemical exposures--and chemicals include oxygen, water, body fluids, nutrients and not-so-nutrients in your foods, medications you may take--are among many, many examples of environmental factors that may reach via a chain reaction all the way to your genes. Some of these factors affect your genes by way of your sensory system: A hug, an angry encounter, a sick child, a laugh with a friend--you respond to each of these environmental influences, often by way of hormones that have a chat with your cells. Your cells respond by adjusting how they use the code in the nucleus so that in the face of anger or love or worry, your body still functions within the essential parameters of life. Below, we list with tongue slightly in cheek a sampling of other factors that constitute an "environment" that could influence your genes and how your cell uses them and the proteins they encode. Whether you know it or not, you're encountering a million factors every day, big and small, that may trigger some effect way down there in the nuclear vaults of your cells, one that reverberates body wide.
Some examples of "environment" that might influence genes
Environmental influence on genes and how your cells use their instructions and the resulting proteins can come from almost anywhere, any factor, from outside of you and within you. It's not just about exposures to "bad" chemicals or "toxins." While the list of potential environmental factors influencing genes and how the cell uses them is practically infinite, we give you just a few examples for thought below:
- Your parents, siblings, friends, extended family, co-workers, soccer team--you know, other people
- The billions of microbes that live on you and in you
- Lifestyle factors like diet, exercise, sleep, stress
- A dusty house
- A clean house
- Hormones, from inside and out
- The womb and factors therein
- Playing outside
- Playing inside
- Having sex
- Abstaining from sex
- Your job
- Other genes
- Learning things
- Not learning things
- Birth order
- Watching sports
- Playing sports
- Sitting a lot
- Standing a lot
- The Sun (and just about everything under it)
By Emily Willingham, DXS managing editor
These views are the opinion of the author and do not necessarily either reflect or disagree with those of the DXS editorial team.