Some publishers accept only plain text About the Author boxes, so you must write a plain text version for each article you submit.
Here's how a plain text About the Author box might look:
Joe Hammerhead has been a professional contractor for 25 years. Learn how you can cut your project time in half with his revolutionary new toolbox organizer at http://www.joeshardwaresupplies.com.
Be sure to include a fully qualified link (for example http://www.joeshardwaresupplies.com) in your plain text About the Author box. This way all your readers will know how to find you. And many content management systems used by editors and publishers will automatically convert them into clickable links. Even better!