The Taste of Blood

<p>Human blood and floral nectar are both appetizing meals to a hungry female mosquito, yet each meal fulfills a distinct nutritional requirement. While protein obtained from blood is required for females to develop eggs and successfully reproduce, carbohydrates supplied from plant nectar are sufficient for energy metabolism in both females and males. To procure essential nutrients from these distinct food sources, females employ two mutually exclusive feeding programs with unique sensory appendages, meal sizes, digestive tract targets, and metabolic fates. When a female is ready to reproduce, she must selectively seek the taste of blood and ignore the sweet taste of nectar. How does she flexibly modify her preference for the taste of blood to select the feeding program that satisfies her current metabolic needs? Here we investigated the syringe-like blood-feeding appendage, the stylet, and discovered a population of sexually dimorphic chemosensory neurons that are the first neurons to contact blood as a mosquito bites her victim. Using pan-neuronal GCaMP calcium imaging, we found that stylet neurons robustly respond to blood and its components but are insensitive to nectar-specific sugars. The complex mixture of blood is detected by four functionally distinct stylet neuron classes, each tuned to specific blood components associated with diverse taste qualities. Surprisingly, one subset contained polymodal "Integrator" neurons that responded only to mixtures of blood components belonging to distinct taste qualities. What functional role does taste quality integration play in Ae. aegypti? We discovered that Integrator neurons selectively respond to physiological levels of blood glucose only in the presence of additional blood components like NaCl and NaHCO₃. Integrator neurons, like all remaining stylet neurons, are insensitive to nectar-specific sugars. Since glucose is the only redundant cue in blood and nectar, this unconventional taste coding mechanism confers context-specific information to distinguish between glucose present in blood versus nectar. Together these experiments reveal that specialized stylet neurons innately encode the distinction between blood and nectar at the very first level of sensory detection. This innate ability to recognize blood is the basis of global vector-borne disease transmission and is a remarkable example of how specialists can adopt exceptional neural coding strategies to thrive in their niche.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Thesis

Year

2021

Author dc:creator

• Jove, Veronica

Contributors dc:contributor

• Leslie B. Vosshall

• mosquito feeding behavior
• stylet neurons
• taste coding
• blood detection
• nectar discrimination
• vector-borne disease
• Life Sciences

Repository record dc:identifier

https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/608

OAI identifier oai:identifier

oai:digitalcommons.rockefeller.edu:student_theses_and_dissertations-1613