Wada Laboratory

We are interested in how an individual’s phenotype, beyond its genetic programming, is shaped by maternal cues, stress hormones, and nutritional and toxicological stressors.

 

Our research has examined how early exposures to stress hormone and toxicants affect health of individuals. The first sign of distress is a rise in plasma glucocorticoids (GCs), including corticosterone and cortisol. This is thought to increase fitness of individuals by facilitating behaviors and physiology to escape from and withstand the stressful situation. However, GCs can be detrimental when chronically elevated, as GCs slow down growth and disrupt neurogenesis. This cost-benefit balance is especially important for altricial species where extensive development takes place outside of the protection of the womb or egg. We conducted a series of experiments to determine how suboptimal incubation temperatures and early exposure to GCs, mercury, or nutritional stress affect stress physiology in several song birds. We found that young hatched from eggs that were incubated at suboptimal temperature transiently increases adrenocortical responses to capture and handling stress. In contrast, early exposure to mercury through nestling diet and maternal deposition of mercury into eggs suppresses adrenocortical responses to handling stress. Food restriction often elevates GCs in birds. When nestlings are food restricted during nestling period did not alter growth rate. In contrast, food restriction during a juvenile period increased somatic growth, body fat, and immune function.

 

We are also interested in the effects of developmental stress on gene expression and epigenetic modification related to stress physiology. 

 

For more details, please click below for related articles on the topic.

 

Kriengwatana B, Wada H, Macmillan A, MacDougall-Shackleton SA (2013). Juvenile nutritional stress affects growth rate, adult organ mass, and innate immune function in zebra finches (Taeniopygia guttata). Physiological and Biochemical Zoology 86 (6): 769-781.

Wada H, Bergeron CM, McNabb FMA, Todd BD, Hopkins WA (2011). Dietary mercury has no observable effects on thyroid-mediated processes and fitness-related traits in wood frogs. Environmental Science & Technology 45: 7915–7922.

Bergeron CM, Bodinof CM, Budischak SA, Wada H, Unrine JM, Hopkins WA (2011). Counterbalancing effects of maternal mercury exposure during different stages of early ontogeny. Environmental Pollution 409: 4746-4752.

Wada H, Cristol DA, McNabb FMA, and Hopkins WA (2009). Suppressed adrenocortical responses and triiodothyronine levels in birds near a mercury-contaminated river. Environmental Science and Technology 43, 6031-6038.