More About Pitx1 Expression
In the stickleback fish, pelvic-fin reduction resulted from changes in the regulatory switch elements of the Pitx1 gene. In the marine ancestor, the Pitx1 gene is activated in the pelvic-fin region during development to generate the fin. In the pelvic-reduced stickleback, the regulatory switch that normally turns on the Pitx1 gene is either missing or non-functional.
Pitx1 Expression Background
In the development of the stickleback fish, the Pitx1 gene performs different jobs in different parts of the fish at different times. Pitx1 is expressed during the development of the pituitary gland (from which the gene's name derives), the jaw, and the pelvis and its associated spines. Multiple switch regions upstream of the Pitx1 gene manage this differential expression. A mutation or inactivation of one of the switch regions affects only a particular part of the fish, allowing Pitx1 to continue functioning elsewhere. This developmental mechanism explains how the freshwater Paxton Lake stickleback could quickly evolve to lose its pelvis and spines—only the switch region controlling Pitx1 in the pelvis would have to be affected.
From Lecture Three of the 2005 Holiday Lectures Series "Evolution: Constant Change and Common Threads"
Pitx1 Expression Teaching Tips
The animations in this section have a wide variety of classroom applications. Use the tips below to get started but look for more specific teaching tips in the near future. Please tell us how you are using the animations in your classroom by sending e-mail to firstname.lastname@example.org.
- Use the animations to make abstract scientific ideas visible and concrete.
- Explain important scientific principles through the animations. For example, the biological clocks animations can be used to demonstrate the fundamentals of transcription and translation.
- Make sure that students learn the material by repeating sections of the animations as often as you think necessary to reinforce underlying scientific principles. You can start, restart, and play back sections of the animations.
- Urge students to use the animations in accordance with their own learning styles. Students who are more visually oriented can watch the animations first and read the text later, while others might prefer to read the explanations first and then view the graphics.
- Incorporate the animations into Web-based learning modules that you create to supplement your classroom curricula.
- Encourage students to incorporate the animations into their own Web-based projects.
The 2005 Holiday Lectures Series "Evolution: Constant Change and Common Threads"
Pitx1 Expression Credits
Director: Dennis Liu, Ph.D.
Scientific Direction: David M. Kingsley, Ph. D.
Scientific Content: Satoshi Amagai, Ph.D.
Animator: Blake Porch