“Only nature can paint the gorgeous colors and patterns on a butterfly’s wings. But scientists said on Monday that they have mastered the first steps and hope in time to control the entire coloring system, making it possible to design living butterfly wings. The patterning and colors on butterflies’ wings are governed by suites of genes. The new Crispr-Cas gene-editing technique now makes it much easier to figure out what a gene does by deleting it and seeing what happens. A group led by Linlin Zhang and Robert D. Reed of Cornell University has found that a gene called optix has a remarkable role: It controls all the color in a butterfly’s wing. When optix is deleted from the Gulf fritillary’s eggs, the resulting adult butterflies, which are mostly deep brown, wear a ghostly black and silver livery.” N. Wade, The New York Times
ESL Voices Lesson Plan for this post with Answer Key
“That’s because in the absence of the optix gene, the butterfly’s scales produce melanin, a black pigment, instead of the usual chestnut coloring. The biologists had already suspected that optix played a role in activating the butterfly’s brown pigment. But they were surprised that the black pigment was turned on in the absence of optix.
A further surprise came when they turned off the optix gene in a second species, the buckeye. The butterfly’s usual browns and yellows disappeared, replaced by scales of a blazing iridescent blue.
A second group, led by Anyi Mazo-Vargas of Cornell University and Araud Martin of George Washington University, has explored the role of a gene called WntA, which plays a powerful role in the patterning of butterflies’ wings.
The standard pattern of nymphalid butterflies, a 90-million-year-old family of some 6,000 different species, consists of four bands, parallel to the body, that run between it and the edge of the wings. The second band, called the central symmetry system, contains the pattern in the middle of the wings, and the third band holds the eye spots.
Dr. Martin’s team found that when they delete the WntA gene with the Crispr technique, the central symmetry system band disappears entirely from the wings of the speckled wood and buckeye butterflies.
But in other species, the loss of WntA has very different effects, suggesting that the gene has been adapted many times to play different patterning roles as new butterfly species evolved.
In the monarch butterfly, for instance, loss of WntA affects an almost invisible white line that edges the distinctive black lines that delineate the wing’s veins. In the absence of WntA, the white lines expand into the areas between the veins, replacing the distinctive orange pigment.
‘A big question in evolutionary biology is how do you rewire these gene networks,’ Dr. Reed said.
Both Dr. Reed and Dr. Martin are enthralled by the ease and power of the Crispr gene-editing tool, invented in 2012. Before, they could infer what a gene might do but couldn’t prove it.”
NOTE: Lessons can also be used with native English speakers.
Level: Intermediate – Advanced
Language Skills: Reading, writing, and speaking. Vocabulary and grammar activities are included.
Time: Approximately 2 hours.
Materials: Student handout (from this lesson) and access to news article.
Objective: Students will read and discuss the article with a focus on improving reading comprehension and learning new vocabulary. At the end of the lesson students will express their personal views on the topic through group work and writing.
I. Pre-Reading Activities
The K-W-L chart is used to activate students’ background knowledge of a topic in order to enhance their comprehension skills.
Directions: Have students use the KWL chart to list the information they already know about butterflies in general. Later in the Post- Reading segment of the lesson, students can fill in what they’ve learned about the topic.
II. While Reading Activities
Directions: Students are to infer the meanings of the words in bold taken from the article. They may use a dictionary, thesaurus, and Word Chart for assistance.
- “That knocked our socks off,” Dr. Reed said.
- The butterfly’s scales can produce melanin.
- There are many species of butterflies.
- One study shows how species evolve different forms.
- A DNA molecule specifies the 3-D structures of the body.
- When butterflies evolved they recruited a different set of genes.
- The standard pattern of nymphalid butterflies had changed.
- Scientists found that when they delete the WntA gene the central symmetry system band disappears entirely.
- The white lines expand into the areas between the veins on the monarch butterfly.
- The monarch butterfly has a distinctive orange pigment.
Directions: Place students in groups and after they have read the entire article, have them complete the following sentences taken from the article. They can use the words and terms from the list provided, or provide their own terms. They are to find the meanings of any new vocabulary.
The WntA___ becomes ___in the ___stage, impressing its patterning ___on the ___wing structures. Dr. Martin sees the WntA___ as a sketching___ that the outline of the wing -___and the optix gene studied by Dr. Reed’s group as a “paintbrush” ___that fills in the color.
WORD LIST: defines, gene, design, embryonic, tool, information, gene, active, caterpillar, gene
Grammar Focus: Prepositions
Directions: The following sentences are from the news article. For each sentence choose the correct preposition from the choices listed. Note that not all prepositions listed are in the article.
Prepositions: in, for, of, with, by, on, at, to, as, into, across, around, over, through, from, during, up, off,
The biologists had already suspected that optix played a role ___activating the butterfly’s brown pigment. But they were surprised that the black pigment was turned ___ ___the absence ___optix. Dr. Reed hopes___ time ___understand the patterning mechanism so well that he will be able ___recreate the pattern ___one butterfly’s wings___those ___a second species. But understanding butterfly wing patterning is just a step___ addressing larger questions___evolutionary biology.
III. Post Reading Activities
Directions: Have students use the WH-question format to discuss or to write the main points from the article.
Who or What is the article about?
Where does the action/event take place?
When does the action/event take place?
Why did the action/event occur?
How did the action/event occur?
Discussion for Comprehension /Writing
Directions: Place students in groups Have each group list 3 questions they would like to ask any person mentioned in the article. Groups share questions as a class.
1-Minute Free Writing Exercise
Directions: Allow students 1 minute to write down one new idea they’ve learned from the reading. Ask them to write down one thing they did not understand in the reading. Review the responses as a class. Note: For the lower levels allow more time for this writing activity.