Janzen, Laine et al. (2011) International Worm Meeting "Forward screen for mutants lacking a food block on olfactory adaptation."

L'Etoile, Noelle, Cha, Amanda, Ghafari, Ghazal, Llamas, Sara, Young, Jared, Janzen, Laine, Stinson, Pilar, Summers, Stephanie

[International Worm Meeting, 2011]

Context cues play a role in compulsive and addictive behaviors by endowing accompanying stimuli with increased salience. For example, olfactory cues such as food odors accompany the reinforcing stimulus of the food itself, and thus stimulate cravings for the reinforcing stimulus. We suggest important modulation of odor processing may occur in olfactory sensory neurons, and indeed recent studies have indicated that responses to odors may be modified early in the olfactory pathway (1,2). Olfactory adaptation is a basic form of learning that causes desensitization of an organism to an odorant after a prolonged period of exposure. Studies have shown that adaptation to an odorant can be repressed by the presence of food in the model organism C.elegans (3,4). This block of adaptation involves inhibition of changes in the primary sensory neuron which are associated with olfactory adaptation. As part of a larger project to study the molecular, cell biological, and circuit level mechanisms by which food-derived signals affect odor signaling and long-term plasticity in the model organism C.elegans, this project will attempt to identify new genes involved in the inhibition of long-term neuronal plasticity by food signaling in the sensory neuron (AWC). To identify new genes involved in the food block on adaptation, we are using an unbiased forward genetic screen to isolate mutants. This foundational project will contribute to a larger endeavor to reveal how rewarding stimuli alter signal processing within the primary sensory neuron and may inspire therapies for controlling debilitating compulsive behaviors, such as over eating or drug addiction. 1. Li W, Howard JD, Parrish TB, Gottfried JA. Aversive learning enhances perceptual and cortical discrimination of indiscriminable odor cues. Science. 2008 Mar 28;319(5871):1842-5. 2. Doucette W, Gire DH, Whitesell J, Carmean V, Lucero MT, Restrepo D. Associative Cortex Features in the First Olfactory Brain Relay Station, Neuron. 2011 Mar;69(6):1176-1187. 3. L'Etoile ND, Coburn CM, Eastham J, Kistler A, Gallegos G, Bargmann CI. The cyclic GMP-dependent protein kinase EGL-4 regulates olfactory adaptation in C. elegans. Neuron. 2002 Dec 19;36(6):1079-89. 4. Colbert HA, Bargmann CI. Environmental signals modulate olfactory acuity, discrimination, and memory in Caenorhabditis elegans. Learn Mem. 1997 Jul-Aug;4(2):179-91.

Cha, Amanda et al. (2013) International Worm Meeting "A forward screen to identify genes involved in the blockage of olfactory adaptation by food in C. elegans."

Knight, Jamie, Young, Jared, Engelhardt, Marie, Kettellapper, Kelsi, L'Etoile, Noelle, Summers, Stephanie, Cha, Amanda, Stinson, Pilar, Janzen, Laine, Ghafari, Ghazal

[International Worm Meeting, 2013]

C. elegans is attracted to specific odors sensed by the paired AWC olfactory sensory neurons; however, the attraction decreases if exposure occurs in the absence of food, referred to as olfactory adaptation. We seek to further explore odor processing and its interaction with food sensory signals in the model organism C. elegans. Adaptation in C. elegans to particular odorants does not occur when exposure is accompanied by Escherichia coli, a food source for the worm. Here we report results from a forward screen to identify genes involved in the block of olfactory adaptation by food. In the forward screen, F2 mutants were isolated based on their lack of attraction to an odor after the odor was presented along with food. The screen was carried out and 33 worms isolated as possibly interesting mutants. Further analysis, aimed at identifying lines with robust phenotypes, is focused on 7 of these lines.

Stingl P (1997) Int J Dermatol "Onchocerciasis: clinical presentation and host parasite interactions in patients of southern Sudan."

Stingl P

[Int J Dermatol, 1997]

BACKGROUND: Onchocerciasis, an infection by the filarial nematode Onchoverca volvulus, is widely distributed in tropical Africa and of great dermatologic interest. This study analyses the dermatologic presentation and tries to determine the correlations between clinical disease and host parasite interactions in onchocerciasis patients of the Southern Sudan. METHODS: We performed clinical and histopathologic investigations in patients with onchocerciasis in the Wau District, Bahr el Ghazal Province, Southern Sudan. As well as a detailed clinical skin examination, skin biopsies were taken, processed, and investigated for type and degree of host tissue response. Parasitologic, clinical, and histopathologic findings were evaluated. RESULTS: Onchocerciasis appears with a variety of severe skin lesions. Central is a pruritic rash. Long-standing cases develop extensive pigmentary changes and impressive signs of skin tissue exhaustion. Cellular host tissue responses to degenerating skin microfilariae seem to play a key role in the development of skin pathology. The degree of host response appears to be inversely proportional to the host's microfilarial load. CONCLUSIONS: Onchocerciasis represents a health problem of great dermatologic importance in Southern Sudan. The study results demonstrate clinical variations in onchocerciasis and provide support for the existence of a disease spectrum.