Cameron Lait, Mentor

Loading samples of regurgitant into the High Performance Liquid Chromatograph to identify the compounds that are in it. The monitor at top center displays the results of the analysis.

Loading the ultracentrifuge with vials containing microsomes and cytosol that were previously separated from other material. The ultracentrifuge will be run at 32,000 RPM at 4°C for 90 minutes to isolate the microsomes for protein analysis.

A close-up look at tobacco leaf damage by the tobacco hornworm, Manduca sexta. This plant was sprayed with the amino acid valine.

Manduca sexta feeding on the tobacco plant control.

Mirian's Abstract:

Coupling of Amino Acids to Linolenic Acid in vitro by Tobacco Hornworm Microsomes.

Plants actively produce and release volatile chemical signals in response to fatty acid amide (FAA) elicitors found in the oral secretions of attacking Lepidopterous herbivores. These volatile chemicals play a major role in enabling natural enemies of the herbivores, such as insect parasitoids, to locate hosts. The FAA elicitors N-linolenoyl-L-glutamine and N-linolenoyl-L-glutamic acid have been identified in tobacco hornworm (THW) oral secretions and it was recently determined that enzymes present in several of the caterpillar's tissues were involved with their biosynthesis. The specificity of enzymes responsible for the coupling of amino acids to linolenic acid to yield elicitors has not been previously studied. We determined that 4 hydrophilic (polar) and 4 hydrophobic amino acids could be coupled to linolenic acid by THW microsomes at an optimum pH of 8.0. Glutamic acid, found in one of the THW elicitors, did not couple to linolenic acid under the same experimental conditions as the other amino acids that did couple.