The pearl crescent (Phyciodes tharos) is one of the most abundant small butterflies in eastern North America. Favoring open, sunny areas like roadsides, fields, and gardens as their habitat, pearl crescents lay their eggs on the underside of aster leaves. Asters contain a chemical known as germacrene D, a chiral product (its mirror images cannot be superimposed on one another) containing only one chiral center (an atom that is bound to four different atoms). The two different mirror images of germacrene D are referred to as enantiomers and differ in the direction they rotate plane polarized light: the (+) enantiomer rotates it to the right while the (-) enantiomer rotates it to the left. Previous research has shown that asters produce varying amounts of each enantomeric form of germacrene D and that the ratio between the two enantiomers varies not only between different aster species but also between different individuals within the same species. Studies indicate that some insects are able to distinguish between the two enantiomers through the use of their olfactory receptor neuron, and it is strongly believed that female pearl crescents prefer to lay their eggs on aster plants that contain higher amounts of (-)-germacrene D.
Student researchers under the advisement of Robin Kinnel, the Silas D. Childs Professor of Chemistry, have been working on what is affectionately known as "the butterfly project." The goal of the project is to extract the chemical from natural sources and to synthesize it in the lab in order to show unambiguously that it is (-)-germacrene D and not (+)-germacrene D that acts as a chemical stimulus for the egg laying of P. tharos.
Last summer, Amy Klockowski '09 (Rome, N.Y.) worked to isolate and extract pure germacrene D from two different species of plant: Goldenrod (Solidago altissima) and New England Aster (Aster novae-angliae). This summer, Klockowski is continuing her work on the butterfly project by attempting to synthesize optically pure (+)-germacrene D. To synthesize the germacrene D, she needs to create two starting materials: cryptone and allene. Thus far, she has successfully synthesized both cryptone from S-perillyl alcohol and allene, which exists in the gas phase at room temperature. She is currently in the process of testing her samples' purity and optical rotation. Her next steps include a series of photochemical reactions, which will complete the synthesis of (+)-Germacrene D. In the future, Klockowski says it will be possible to use the germacrene D she is synthesizing to see how pearl crescent antennae (which contain the olfactory receptor neurons) react to a sample of pure (+)-germacrene and pure (-)-germacrene.
Klockowski is chemistry major with a history minor and a member of the woman's rugby team. She also works at Café Opus and regularly engages in volunteer activities.
-- by Nick Berry '09
Student researchers under the advisement of Robin Kinnel, the Silas D. Childs Professor of Chemistry, have been working on what is affectionately known as "the butterfly project." The goal of the project is to extract the chemical from natural sources and to synthesize it in the lab in order to show unambiguously that it is (-)-germacrene D and not (+)-germacrene D that acts as a chemical stimulus for the egg laying of P. tharos.
Last summer, Amy Klockowski '09 (Rome, N.Y.) worked to isolate and extract pure germacrene D from two different species of plant: Goldenrod (Solidago altissima) and New England Aster (Aster novae-angliae). This summer, Klockowski is continuing her work on the butterfly project by attempting to synthesize optically pure (+)-germacrene D. To synthesize the germacrene D, she needs to create two starting materials: cryptone and allene. Thus far, she has successfully synthesized both cryptone from S-perillyl alcohol and allene, which exists in the gas phase at room temperature. She is currently in the process of testing her samples' purity and optical rotation. Her next steps include a series of photochemical reactions, which will complete the synthesis of (+)-Germacrene D. In the future, Klockowski says it will be possible to use the germacrene D she is synthesizing to see how pearl crescent antennae (which contain the olfactory receptor neurons) react to a sample of pure (+)-germacrene and pure (-)-germacrene.
Klockowski is chemistry major with a history minor and a member of the woman's rugby team. She also works at Café Opus and regularly engages in volunteer activities.
-- by Nick Berry '09
