Abraham Beyene: "Imaging neuronal chemical efflux using DNA-carbon nanotube hybrid materials"

Hosted by the Optical Interest Group, Janelia Group Leader Abraham Beyene will present "Imaging neuronal chemical efflux using DNA-carbon nanotube hybrid materials."

Abstract: Neurons are the building blocks of the nervous system and constitute the key units of information processing in the brain. To carry out their function, neurons need to be able to communicate with each other. One primary mechanism of communication between neurons is through chemical signalling molecules that are released by one neuron and get “sensed” by other neurons. Synapses are the primary location where chemical signalling occurs. Despite the central role that synapses play in information processing in the brain, many tools that are used to study them do not enable direct measurement of the chemicals they release. This is because most neurochemical measurements rely on ensemble averages from population of synapses and have poor spatial resolution. In my lab, we develop technologies that enables us to visualize the spatiotemporal dynamics of release with single synapse resolution. We do this for a class of signalling molecules in the brain called monoamines which are released by neurons that play key roles in learning, motivation, attention, and other related behaviours. To enable measuring chemical efflux at the spatial resolution of a single synapse, my lab uses the brain’s dopamine neurons as a model and employs tools that are inspired by materials chemistry. In particular, near infrared (NIR) fluorescent single wall carbon nanotubes (SWCNT) possess advantageous photophysical properties that can be leveraged for applications in neurobiology. SWCNTs fluoresce in the near infrared region of the spectrum (~ 900—1300 nm), which is suitable for imaging in biological specimens because of reduced scattering of NIR photons and minimal tissue autofluorescence. SWCNT exhibit superior photostability and are non-photobleaching on time scales of interest to imaging in biology. To take advantage of their photophysical properties, SWCNTs need to be disperse in solution through surface functionalization with molecular complexes. Single strand DNA oligonucleotides (ssDNA) are among a wide range of molecular motifs that are employed for this purpose. In this talk, I will introduce ssDNA-SWCNT hybrid materials that serves as a fluorescent turn-on sensor for a class of neuromodulators called catecholamines, of which dopamine is one. The turn-on response is driven by quenching of intrinsic SWCNT fluorescence caused by certain sequences of ssDNA, which is rescued by catecholamines, including dopamine. I will discuss what we know so far about the mechanistic basis of this class of sensors. Moreover, I will talk about the progress we’ve made in the lab to measure the spatiotemporal dynamics of the catecholamine neuromodulator dopamine, with the spatial resolution of a single synapse, and quantal sensitivity, using optical technologies developed from ssDNASWCNT hybrid materials. In conclusion, my talk will demonstrate how a hybrid between an inorganic nanoparticle and one of the central molecules in biology, DNA, form supramolecular complexes that have enabled us to visualize chemical efflux from synapses, and allowed us to embark on several studies that otherwise would not be possible using conventional methods of inquiry.

More information about Janelia’s Optical Interest Group can be found here: https://www.janelia.org/OIG

Видео Abraham Beyene: "Imaging neuronal chemical efflux using DNA-carbon nanotube hybrid materials" канала Howard Hughes Medical Institute (HHMI)