Transgenic Fly Lab Introduction

Welcome to the Virtual Transgenic Fly Lab. The lab will familiarize you with the science and techniques used to make transgenic flies. Transgenic organisms, which contain DNA that is inserted experimentally, are used to study many biological processes. In this lab, you will create a transgenic fly to study circadian rhythms. (Click here for more on experimental design.) The fly glows only when a certain gene involved in circadian rhythms is activated. After making the glowing fly, you will use it to explore basic principles of circadian biology and genetics.

Teachers: Click here for more information on how this exercise can be used in your classes.

Basic Steps

1. Make transgenic flies.

• Prepare DNA that will be incorporated into the fly genome.
• Prepare fly embryos.
• Inject fly embryos with DNA.
• Breed flies.
• Select transgenic progeny.
• Examine light output from transgenic adults.

The period gene is a key component of the fly's molecular clock (Bargiello, et al., 1984; Darlington et al. 1998; Wager-Smith, and Kay, 2000; Young 2000). The period (or per) gene's transcription and translation oscillate in a regular pattern that has a period of 24 hours. A mutation in this gene results in a fly with an altered period; the name period was therefore given to this gene (Konopka and Benzer 1971). (Click here for more on the discovery of the period gene.) This predictable pattern is harnessed in the experiments here to provide a window into how clock molecules change. Specifically, part of the period gene is linked to the luciferase gene (per-luc) such that whenever the period gene is "on," light is produced in the cells where period gene transcription is occurring (Brandes et al. 1996). This elegant model allows us to look at changes in genes simply by looking at the glow of these transgenic flies.




2. Use transgenic flies to study circadian rhythms and genetics.

• Measure per-luc gene expression (that is, light emissions) under different light-dark conditions.
• Examine different fly body parts for per-luc expression.

Learning Objectives

• Understand how recombinant DNA technology is used to produce transgenic flies.
• Use light production as an external marker of internal molecular events.
• Explore the relationship between genes and behavior.
• Understand how transgenic organisms can be used to explore complex biological processes.
• Learn that all organisms contain an internal molecular clock that regulates daily rhythms.

Throughout each exercise, this window will display information explaining what you are doing. All the interactions, however, will be done inside the interactive window to the left. The small gray box below the interactive window will give you specific instructions on what objects to click on.