Receptor+Chemotaxis

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 * How Worms Find Food and Avoid Toxins Using G Protein-Coupled Receptors to Detect Volatile Chemicals: Testing for Hexane with Caenorhabditis elegans. Hagop Toghramadjian, Sarah Hays **

The purpose of this lab was to test the chemotaxis response of the nematode worm //C. elegans// to previously identified attractants and repellants. Once the assay was established, the next step was to test chemotaxis response to a potential soil toxin. To accomplish this task, wild-type and mutant strains of //C. elegans// were obtained from the stock center at the University of Minnesota. Adult worms were isolated and placed onto chemotaxis assay plates. The volatile odorants were dissolved in ethanol and placed at one end of the plate, and a control drop of ethanol was placed on the opposite side. //C. elegans// were allowed to chemotax for 2-3 hours and then their relative movement towards or away from the volatile odorant was recorded. Wild-type and mutant //C. elegans// differed in their chemotaxis response to the previously characterized odorants. In addition, an attraction to the potential soil toxin hexane, was observed. In phase two, the concentration of hexane was varied in order to observe the //C. elegans// response to increased concentration. When matched with the isoamyl alcohol, acetone and octanol models, //C.elegans//' response to hexane indicated repulsion, though response varied for different types of the worm. //Caenorhabditis elegans //’ apparent repulsion from hexane may prove very useful in testing for the pollutant, especially because the worm can detect very low concentrations.

Keywords: //C// //aenorhabditis ////elegans, //hexane, isoamyl alcohol, acetone, octanol, gasoline pollution, chemotaxis, attraction, indifference, repulsion, wild type

apparatus: http://www.etsy.com/listing/88344894/mediterranean-dreams-adjustable-ring?ref=sr_gallery_5&ga_search_submit=&ga_search_query=rings&ga_order=most_relevant&ga_ship_to=US&ga_view_type=gallery&ga_page=3&ga_search_type=handmade&ga_facet=handmade Figure 1: Pipetting the worms onto the chemotaxis plate

Summary Graphic

Key Sources: Bargmann, C. (2006). Chemosensation in C. elegans. //WormBook//. Retrieved February 16, 2012, from [|http://www.wormbook.org/chapters/www_chemosensation/chemosensation.html#sec1_3]

Liao, C., Gock, A., Michie, M., Morton, B., Anderson, A., & Trowell, S. (2010). Behavioural and Genetic Evidence for C. elegans' Ability to Detect Volatile Chemicals Associated with Explosives //PLoS ONE, 5 // <span style="font-family: 'Times New Roman',serif; font-size: 12pt;"> (9) DOI: <span style="color: windowtext; font-family: 'Times New Roman',serif; font-size: 12pt;">[|10.1371/journal.pone.0012615]

//Hofler C. & Koelle M. R. (2011). AGS-3 and RIC-8 Activate Gαo during Food Deprivation. The Journal of Neuroscience, 31, 11553-11562.//

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;">Shields, J.D. (2007). Autologous Chemotaxis as a Mechanism of Tumor Cell Homing to Lymphatics via Interstitial Flow and Autocrine CCR7 Signaling. //Cancer Cell//, 11, 526538.

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;">Schmitz, C., Kinge, P. & Hutter, H. (2007) Axon Guidance Genes Identified in a Large-Scale RNAi screen using the RNAi-hypersensitive //Caenorhabditis elegans// strains //nre 1(hdR20)lin-15b(hd126). Proceedings of the National Academy of Sciences,// 104, 834 839

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;">Terrill, W. F. & Dusenbery, D. B. (1996). Threshold Chemosensitivity and Hypothetical Chemoreceptor Function of the nematode //Caenorhabditis elegans. Journal of Chemical Ecology,// 22, <span class="pagination" style="font-family: 'Times New Roman','serif'; font-size: 16px;">1463-1475

<span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Titus, M, personal communication, January 7, 2012