REVIVING AN ENDANGERED TOPIC IN HIGH SCHOOL SCIENCE CLASSROOMS

by Matt Stevens

Randy Good became concerned last spring when he saw weeds overtaking a plot of land at Azusa High School. Good had taught biology and chemistry at the school for 14 years, and he lamented the sorry state of the field that had once been used for a popular horticulture class. Since the departure of a teacher only two years earlier, horticulture had dropped off the schedule of classes.

“I thought I’d better do something,” he says, “before the students lost the field as well as a greenhouse that had been used for the class.”

Good persuaded the principal to revive the class and then signed on to teach it this fall. He got an early start this summer by playing the role of student at The Huntington’s Botanical Center.

The “Grounding in Botany” course began in 2004 through a grant from the National Science Foundation. For two years, biologist Martha Kirouac, an educator at The Huntington, ran a one-week summer workshop for 15 to 20 Southern California high school science teachers, who received small stipends as well as grants for classroom supplies upon completion of the course. This year a grant from the Arthur Vining Davis Foundations helped expand the program to five weeks and brought in Huntington Botanical Educator Mike Kerkman as an additional instructor.

“We’re trying to improve high school teachers’ understanding of botany and developmental biology,” says Kirouac. “If we engage them in these topics, then they can teach the basics with greater ease, confidence, and enthusiasm.”

Immersion for some and refresher for others, the course balances lectures and labs with guest presentations from professors and graduate students from Caltech and UC Irvine.

Gerard Besina, who teaches biology at Paramount High School, relished the opportunity to experience the labs as his students will be experiencing them.

“Grounding in Botany is inquiry based—meaning we are discovering things as we go,” says Besina, who has long kept plants in his classroom but never quite found a place for them in his lectures and labs.

This kind of approach encourages students to ask questions that they can then answer through further exploration. Besina and Good hope their enthusiasm is infectious, but they are also realistic when it comes to addressing one of the most common questions from their students: “Will we have to know this for the test?”

If the subject has anything to do with plants, the answer is probably no. The No Child Left Behind Act of 2001 introduced strict curriculum standards in many subject areas, including biology. Unfortunately, botany has fallen by the wayside, given that the standards emphasize examples from animal biology in addressing topics such as genetics, cell growth, and evolution.

But “plants have tremendous power in the classroom,” says Kirouac. “They can be used in lessons on a surprising number of topics that might be hard to illustrate otherwise.”

On the first day of class, Kirouac and Kerkman passed out containers, fluorescent lights, and Wisconsin Fast Plant seeds. This variety of Brassica rapa earned its nickname after a botanist from the University of Wisconsin accelerated its development cycle through years of selective breeding. The weedy-looking plant—which is related to bok choy, turnips, and rapini—goes from seed to flower to new seeds in about five weeks. The teachers would follow the life cycle of this plant and study not only its development, but the genetics and cells that make development possible.

This little plant is ideal for countless teachers who have limited resources, financial or otherwise. With just a little water and electricity, students have a model organism at their disposal. Like fruit flies, the Fast Plant has a relatively small genome and is amenable to genetic manipulation. Kirouac herself has used everything from fungus in high school to worms in her Caltech doctoral dissertation to explore how differential gene expression is established in cells. (That is, finding out how a toe cell knows to become a toe cell rather than a finger cell, given that the cells of a particular organism all possess the same DNA.) Worms go from egg to adult to new eggs in just three days, making them great candidates for graduate students but perhaps a bit too fast for the high school setting. Students have little trouble maintaining plants, and they can also mix up their menu with beans, radishes, corn, and a variety of other garden-variety specimens—which all possess a range of strengths and weaknesses, depending on the type of questions students might be asking.              

Plants can also provide tangible case studies when a corresponding example from the animal world is impractical. Take cancer, for example. Plants develop tumors, although their cells don’t travel to other parts of the “body” and metastasize into cancer as humans know it. Nonetheless, students can safely conduct experiments and observe out-of-control growth of abnormal cells by infecting sunflower plants with a type of bacterium that induces plant cell growth and division. This lab invariably leads to a discussion of cell division, the differences between animal and plant cells, or the different methods of cancer treatment.

After directing the teachers through the lab in the second week of the course, complete with information on how to order and dispose of the bacteria, Kirouac led the group on a walk through the gardens on a quest to find trees infected with crown gall—those large, bulbous growths that are essentially tumors. (On finding one example, Kirouac assured the group that such a condition is somewhat common and does not usually threaten the survival of a tree.)

Jim Folsom, the Marge and Sherm Telleen Director of the Botanical Gardens, showed how easy it was to exploit the variety of specimens on the Huntington grounds to teach lessons great and small. He took his turn as guest lecturer by leading a field trip through the various gardens, all the while asking deceptively simple questions.

“Which part of this tree is a leaf?” he asked as he positioned the group underneath a Caryota palm tree in The Huntington’s Jungle Garden. Also known as the giant fishtail palm, the tree has massive, fern-like leaves that could each be mistaken for a collection of distinct, smaller leaves. The teachers sensed the trick question but nonetheless stumbled through their answers.

In no time at all, Folsom had jumped from a description of leaves, stems, and roots to a discussion of the plant’s shoot apical meristem. Before giving anyone a chance to say the mouthful five times really fast, Folsom explained that an apical meristem is essentially a growing tip—the node where plant cells develop into flower buds, leaves, or stems. The shoot apical meristem is the primary growing tip that continues to push upward while leaving the entire architecture of a plant in its wake, including other meristems.              

Folsom picked up a long stem and spun it gently, marveling at the concentric arrangement of the flowers and leaves. “It’s like counting the rings on a tree stump,” he explained, showing that the repeating pattern of flowers and stems tells its own story of measurable units of time. With each stop in the garden Folsom managed to take something familiar and convince teachers they were seeing it for the first time.             

Folsom reminded teachers they didn’t need exotic plants and more than a hundred acres at their disposal in order to hook students. “Sure, kids get excited about Venus flytraps, but a head of lettuce will do,” he said. “And you can eat it afterward!”

It turns out that Folsom’s discussion of the shoot apical meristem was a prerequisite for a guest lecture in week four from Elliot Meyerowitz, the George W. Beadle Professor of Biology and chair of the Department of Biology at Caltech. Think of the meristem as the botanical equivalent of the stem cell—both contain undifferentiated cells that have yet to form into a specific cell, be it for a leaf, stem, or flower or an ear, nose, or throat. Meyerowitz has spent the better part of his career trying to figure out how the cells of those growing tips “decide” their fates.

Meyerowitz explained that the model organism of choice in his lab is the Arabidopsis thaliana, more commonly known as thale cress—a small plant related to cabbage and mustard, not to mention the Wisconsin Fast Plant. With tweezers, small brushes, and a fair dose of patience, Meyerowitz and his colleagues can cross-pollinate mutations of the plant—monkeying with the normal four-whorl pattern of the organs of the flowers: four sepals in the outer whorl, then four petals, six stamens, and finally two carpels. While the mutations always contain four whorls (with the customary 4-4-6-2 pattern), the locations of the organs can be altered almost at will.

Meyerowitz is trying to disprove his own theory by testing and testing again. Every configuration he comes up with is consistent with his ABC model—A, B, and C being three distinct gene functions that act in a variety of combinations to specify the location of an organ.

Randy Good is a decade removed from graduate school, so he enjoyed interspersing simulations of high school labs with graduate-style seminars. In addition to Meyerowitz, the teachers heard from José Luis Reichmann, the director of the Gene Expression Center at Caltech, who spoke about microarrays, which allow scientists to profile RNA expression in a genome and compare expression levels under different conditions.

All the cells of a particular organism have the same DNA, but “RNA expression gives the cells their careers,”  Kirouac pointed out. “This microarray technique allows the scientists to better understand how a cell reaches its career goals.”

Eric Mjolsness, an associate professor in the Department of Information and Computer Science at UC Irvine, explained how he applies computation and mathematical models to biological observation. It was Mjolsness’ collaboration with Meyerowitz that brought the high school teachers to The Huntington in the first place. Their work on a project called “The Computable Plant” earned the grant from the National Science Foundation, which included an outreach component as a requirement for funding. The two scientists turned to The Huntington, which brought in Kirouac and later, Kerkman, to bridge the gap between high school curricula and the research world.

Kirouac, Kerkman, and the guest lecturers worked together to emphasize that a model is an extension of a hypothesis. So how practical is it to subject high school teachers to such sophisticated models?

“I look at this program as giving me more tools for my tool belt,” says Mike Milburn, who teaches biology, physical science, and earth science at the Soledad Enrichment Action Charter School in Hollywood. “The more tools I have, the more I can pick and choose from to better communicate a lesson in class.”             

Good appreciated the interplay of regular course lessons and master classes. “If I had heard Meyerowitz’s lecture on my own before taking Grounding in Botany, I wouldn’t have understood most of it.” But instead he was able to parse the details with Meyerowitz after the lecture.

Yet despite the rigor of the guest lectures, Kirouac and Kerkman attempt to present practical tools that can meet teachers’ day-to-day needs in the classroom. The entire set of 31 labs—plus handouts, lecture material, and PowerPoint presentations, including those from guest lecturers—are loaded onto a CD for each teacher. And each lab cross-references the California state standard that it fulfills. Additionally, Kirouac and Kerkman will continue to work with the teachers throughout the academic year in five follow-up workshops.

Joan Stevens, who took the class in the summer of 2004, has a literal interpretation of the term “continuing education.” She has become a fixture at every Huntington professional development opportunity for high school science teachers. A botanist by training, she is embarrassed to admit that before taking the Huntington classes, she hardly used plants in her science classes at Arcadia High School.

But now she conducts numerous labs using plants as a model system in her Advanced Placement biology and environmental science classes, citing a few favorites from her stint at The Huntington. “Students love hands-on activities,” Stevens says. “And they like dirt!”

Stevens developed friendships with the colleagues she met through The Huntington’s courses and shares strategies all the time. “It’s such a treat to connect with teachers from schools throughout Southern California,” she says.

Time will tell if Good will reap the same benefits. For starters, he might want to change his plans a bit regarding that weed-infested field at his high school. In the last week of the course, Kirouac and Kerkman took the teachers to a weedy corner of The Huntington grounds to look at the adaptations and habits of invasive plants. They then ran a lab using computational methods to predict the invasiveness of these plants. As the saying goes, if someone gives you lemons…then devise a high school science lab that shows how citric acid inhibits the reaction rate of catechol oxidation.

Matt Stevens is editor of Huntington Frontiers. Applications for next summer’s Grounding in Botany course are due in the spring. You can find more information at http://www.huntington.org/Education/gib.html.

How a rare Huntington plant might help explain the origin of flowers

What if your research on the evolutionary origin of flowers hinges on a rare plant found in its native habitat only in the far reaches of Namibia and Angola?

Botanist Michael Frohlich faced such a dilemma when he realized he needed to take a close look at the genes of Welwitschia, a bizarre plant that produces just two leaves that grow continuously and get ripped to shreds by the dry desert winds. Individual specimens can live as long as 1,500 years.

Welwitschia is a gymnosperm, which means it produces seeds in exposed structures like cones rather than hidden within the pistils of flowers, as in angiosperms. But the reproductive structure of Welwitschia cones bears an uncanny resemblance to that of flowers—sterile bracts like sepals surround male units with female structures in the center. Botanists have long been trying to explain the origin of flowers, which Darwin once dubbed the “abominable mystery.” Could cones like Welwitschia’s be precursors to the remarkable flower structure?

In the mid-1980s botanists proposed the Anthophyte theory, which said that all flowering plants shared three close gymnosperm relatives, two of which were extinct. This left the Gnetales, a small order that includes Welwitschia. The theory arose from morphological studies—that is, physical observations of shapes, sizes, and structures, including fossil evidence of the two extinct groups.

By the time Frohlich took a sabbatical from his teaching position at Union College, in Schenectady, N.Y., in 1993, technology had advanced so much that botanists were able to study the genes that control individual flower organs. Frohlich spent the year in the Caltech lab of Elliot Meyerowitz, who had already identified the combinatorial relationship of three gene functions in Arabidopsis plants by observing various homeotic mutations—the phenomenon of an organ growing in the wrong location, such as a stamen growing where a petal should be, or vice versa. His so-called ABC model could be applied to other plants, and Frohlich was eager to use it in his work. If the cones of Welwitschia were indeed homologous to flowers, the ABC genes of Welwitschia should be active in the cone in a fashion consistent with Meyerowitz’s model.

As luck would have it, Frohlich did not have to travel all the way to southern Africa to get Welwitschia samples for genetic testing. Caltech is just a few blocks from The Huntington. “Several botanical gardens in the United States have small Welwitschia plants,” says Frohlich, “but only The Huntington has large plants that make many cones—and cones were essential for my project.” He got to work extracting live tissues.

The results did not support the Anthophyte theory after all. Gnetales were closer to other gymnosperms than they were to flowering plants. But Frohlich turned his attention to a different gene after discovering that it appears twice in Welwitschia and other gymnosperms: one copy of the gene is expressed in the production of male cones, while the other is expressed in female cones.

Frohlich hadn’t been the first to notice this gene (called LEAFY, but don’t let that confuse you) or to realize that there is only one copy in angiosperms and that it signals the plant to make flowers. But in 2000, he and his research partner, David S. Parker, found that the lone gene in flowering plants derived from the male-expressed gene of ancient gymnosperms, which led them to propose the Mostly Male Theory of flower evolutionary origins.

In 2002, Frohlich helped found the Floral Genome Project (www.floralgenome.org). By mapping the genomes of 13 flowering plants and two gymnosperms (one of which is Welwitschia), the research team hopes to make further progress in solving the “abominable mystery.” They are now using Welwitschia samples from The Huntington to conduct microarrays—a procedure that helps measure activity of individual genes. This project is part of a growing field called evo-devo—or evolutionary-developmental biology—which combines evolutionary studies, taxonomy, morphology, and molecular genetics.

“We couldn’t have come this far without the use of Welwitschia from The Huntington,” says Frohlich, who is now a botanist at the Natural History Museum in London.

Matt Stevens

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