Profiles

Sara Wasserman

Graduate Student

The ability to evaluate external and internal environmental sensory information is critical across sensory modalities. Temperature recognition is especially crucial for the survival of a number of species. Many organisms depend upon the ability to sense the temperature of their urroundings and their internal temperature and respond accordingly to locate food, keep from drying out, and respond to painfully hot or cold thermal stimuli. The molecular and physiological mechanisms underlying thermosensation remain largely uncharacterized. C. elegans provides a good model system in which to study the molecular and neuronal basis of thermosensory behaviors. The behavior of C. elegans on a spatial or temporal thermal gradient is dependent on a ‘memory’ of their cultivation temperature (Tc). When encountering ambient temperature higher than their cultivation temperature, worms move down the gradient towards colder temperatures (cryophilic behavior). At temperatures of Tc ± 2°C, worms orient perpendicular to the gradient and track isotherms. The memory of the Tc is plastic, and can be reset upon exposure of worms to a new temperature for a prolonged period of time (Figure 1).

While many of the neurons involved in producing the thermotaxis behavior have been identified (Figure 2), the complete neuronal circuit driving this complex behavior remains to be fully characterized. Many genes have also been implicated in mediating this behavior, but we do not yet have a full understanding of their role in generating different aspects of this behavior.

My research is aimed at identifying and characterizing key genes that produce and regulate thermotaxis behavior. I am collaborating with the lab of Aravi Samuel at Harvard to apply quantitative biophysical assays to analyze thermotaxis behaviors. I am also performing calcium imaging experiments in individual neurons to identify the mechanistic basis of the observed phenotypes. As no temperature receptor has been identified in C. elegans, my experiments strive to identify and characterize putative thermo-receptors as well as molecules that contribute to downstream processing of thermal inputs. The characterization of these candidates will also help to further elucidate the neurons involved in specific aspects of this behavior, and define the mechanisms underlying long-term thermosensory behavioral plasticity and isothermal tracking.

Sengupta Lab Publications:

Biron, D.*, Wasserman, S.*, Thomas, J.H., Samuel, A.D., and Sengupta, P. (2008). An olfactory neuron responds stochastically to temperature and modulates Caenorhabditis elegans thermotactic behavior. Proc Natl Acad Sci U S A 105, 11002-11007. [PubMed] (*equal contributors)

Biron, D., Shibuya, M., Gabel, C., Wasserman, S.M., Clark, D.A., Brown, A., Sengupta, P., and Samuel, A.D. (2006). A diacylglycerol kinase modulates long-term thermotactic behavioral plasticity in C. elegans. Nat Neurosci 9, 1499-1505. [PubMed]