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May 10, 2011

Evolution and Medicine – a New Approach for High School Biology

Evolution and Medicine – a New Approach for High School Biology

May 10, 2011

Paul Beardsley

Section IIntroduction

Biological Sciences Curriculum Study

• Established in 1958

• Nonprofit organization

• Three main areas of emphasis– Curriculum Development– Professional Development– Research and Evaluation

NIH Curriculum Supplement Series

Free curriculum supplements http://science.education.nih.gov

NIH – Evolution and Medicine• Sponsored by: 

– National Institute of General Medical Sciences– National Institute of Neurological Disorders and Stroke– National Eye Institute– National Heart, Lung, and Blood Institute– National Institute of Allergy and Infectious Diseases– National Institute on Drug Abuse– National Institute of Dental and Craniofacial Research– National Institute on Aging– National Cancer Institute– National Center for Research Resources– Office of the Director

• What features would you like to see in a short curriculum that focuses on evolution?

Evolution is Relevant— Hillis 2007

• Ten Ways to Improve Evolution Coverage in Biology Textbooks…

1. Demonstrate that evolutionary research is current and ongoing

3. Use fresh examples.

4. Show how evolution is relevant to human lives.

Let’s pause for questions from the audience

Section 2

Overview of Evolution and Medicine

Engage: Ideas about the role of evolution in medicine

• Students provide initial explanations for the evolution of MRSA.

• Students examine data from Pax6, consider how common ancestry explains the value of model organisms.

Adapted from: Washington NL, Haendel MA, Mungall CJ, Ashburner M, Westerfield M, et al. 2009. Linking Human Diseases to Animal Models Using Ontology-Based Phenotype Annotation. PLoS Biology 7(11): e1000247. doi:10.1371/journal.pbio.1000247

Explore: Investigating Lactose Intolerance and Evolution

• Students investigate lactase persistence in humans

– Perform a lab experiment

– Provide initial explanations for patterns

– Study the genetic basis for lactase persistence

– Compare alternative

hypotheses

Explain: Evolutionary processes and patterns inform medicine

• Students solve a medical mystery involving alpha-thalassemia

• Apply natural selection to explain the disease’s high incidence.

Explain: Evolutionary processes and patterns inform medicine

• Students compare sequences across species for gene associated with cleft palette.

• Students explain the results in terms of common ancestry

• Explain how natural selection conserved certain sequences

Elaborate: Using evolution to understand influenza Align sequences of

the hemagglutinin gene

Learn about the hemagglutinin region and the immune system

Relate principles of natural selection to the need for new vaccines

Evaluate: Evaluating evolutionary explanations

• Students evaluate an article about the evolution of vitamin C synthesis written for a school publication

• Compare each example of natural selection encountered in the supplement.

Let’s pause for questions from the audience

Section 3

Lesson 1— Anaridia: An Eye Disease

• Students learn about the rare disease aniridia, caused by mutations in Pax6.

• Students investigate data on Pax6 and contribute their ideas.

What can you infer about the Pax6 gene from the protein sequences from these four species?

Adapted from: Washington NL, Haendel MA, Mungall CJ, Ashburner M, Westerfield M, et al. 2009. Linking Human Diseases to Animal Models Using Ontology-Based Phenotype Annotation. PLoS Biology 7(11): e1000247. doi:10.1371/journal.pbio.1000247

On the basis of the pictures, do you think the function of the Pax6 gene is similar in all four species? Explain your reasoning.

Transition to model species…

• Does the evolutionary tree suggest that the mouse is more closely related to the zebrafish or the fruit fly?

• How would students answer?– A. Zebrafish– B. Fruitfly– C. Don’t know

Do you think that the common ancestor of fruit flies, zebrafish, mice, and humans had a gene similar to Pax6?

How does shared ancestry explain why scientists can use model organisms to learn about human health?

Let’s pause for questions from the audience

Section 4

Lactose Intolerance and Evolution

Explore: Investigating Lactose Intolerance and Evolution

• Students hear about an Asian teenager who moved to the US and began to suffer digestive problems after consuming milk.

• Investigate simulated lactase samples from patients around the world

Lesson 2: Lactose Intolerance and Evolution

Working site

Lesson 2: Lactase Intolerance and Evolution

Working site

Lesson 2: Lactase Intolerance and Evolution

Working site

Gender

Age

What type of mutation causes the difference between lactase persistence and lactase nonpersistence?

A mutation to the coding region

for the lactase enzyme

A mutation to a regulatory region

for the production of lactase

Scientists have identified specific mutations that cause lactase persistence…

Thinking about genetics

What does it mean for the evolution of lactase persistence if all people who are lactase persistent don’t have Mutation 1?

Explaining the Evolution of Lactase Persistence

1.Culture-historical hypothesis: In populations that herd and milk cows, goats, or camels, lactase persistence provides a selective advantage due to a higher level of nutrition or increased access to water

Explaining the Evolution of Lactase Persistence

2. Calcium hypothesis: •Vitamin D helps the body absorb calcium. We can make vitamin D when UV light penetrates the skin. •Lactose also helps the body absorb calcium found in milk. •In populations exposed to low levels of UV light, lactase persistence provides a selective advantage (higher level of calcium)

Figure 1: The following image shows the average daily ultraviolet (UV) exposure across Earth’s surface. Darker colors indicate greater UV exposure.

Image copyright George Chaplin. Adapted with permission. American Journal of Physical Anthropology, 107(2), 1998, pp. 221-224. Copyright 1998 Wiley-Liss, Inc.

ApproximateTime period

Number of skeletons examined

Possible cases of rickets

3000 BCE 616 6*

CE 400-1000 635 0

CE 800-1100 1055 6

CE 1200 364 1

* Some researchers interpret these skeletons differently and claim that they do not show evidence of rickets.

Let’s pause for questions from the audience

Section 5

Using Evolution to Guide Research

• Students learn about cleft lip and palate

• Gene Irf6 is associated with one form of cleft lip and palate

• Irf6 is active in mice as sides of mouth fuse

• Goal: identify sections of the Irf6 gene that have remained the same over large amounts of time.

Species Time since common ancestry with humans (millions of years)

Nucleotides that are the same (number)

Similarity with human sequence (%)

Chimpanzee 8 1,685 99 Orangutan 15 1,653 97 Rhesus monkey

30 1,628 96

Dog 97 1,221 72 Horse 97 1,209 71 Cat 97 1,149 68 Cow 97 891 52 Rat 91 612 36 Mouse 91 573 34 Guinea pig 91 572 34 Armadillo 105 1,039 61 Opossum 176 518 30

• How much time is involved in the comparison of all four species?

• A – 30 million years• B – 20 million years• C – 10 Million years• D – None of these

Questions about how to calculate time for an evoprint?

• Imagine you had an evoprint with these four species. How much time would be represented in this evoprint?

• Advanced classes: 3rd position in codon

• How does evolution explain why certain regions of the Irf6 gene have not changed over large amounts of time?

Let’s pause for questions from the audience

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