Ernie Hwaun

All Publications

• Creation of an albino squid line by CRISPR-Cas9 and its application for invivo functional imaging of neural activity. Current biology : CB Ahuja, N., Hwaun, E., Pungor, J. R., Rafiq, R., Nemes, S., Sakmar, T., Vogt, M. A., Grasse, B., Diaz Quiroz, J., Montague, T. G., Null, R. W., Dallis, D. N., Gavriouchkina, D., Marletaz, F., Abbo, L., Rokhsar, D. S., Niell, C. M., Soltesz, I., Albertin, C. B., Rosenthal, J. J. 2023

  Abstract

  Cephalopods are remarkable among invertebrates for their cognitive abilities, adaptive camouflage, novel structures, and propensity for recoding proteins through RNA editing. Due to the lack of genetically tractable cephalopod models, however, the mechanisms underlying these innovations are poorly understood. Genome editing tools such as CRISPR-Cas9 allow targeted mutations in diverse species to better link genes and function. One emerging cephalopod model, Euprymna berryi, produces large numbers of embryos that can be easily cultured throughout their life cycle and has a sequenced genome. As proof of principle, we used CRISPR-Cas9 in E.berryi to target the gene for tryptophan 2,3 dioxygenase (TDO), an enzyme required for the formation of ommochromes, the pigments present in the eyes and chromatophores of cephalopods. CRISPR-Cas9 ribonucleoproteins targeting tdo were injected into early embryos and then cultured to adulthood. Unexpectedly, the injected specimens were pigmented, despite verification of indels at the targeted sites by sequencing in injected animals (G0s). A homozygote knockout line for TDO, bred through multiple generations, was also pigmented. Surprisingly, a gene encoding indoleamine 2,3, dioxygenase (IDO), an enzyme that catalyzes the same reaction as TDO in vertebrates, was also present in E.berryi. Double knockouts of both tdo and ido with CRISPR-Cas9 produced an albino phenotype. We demonstrate the utility of these albinos for invivo imaging of Ca2+ signaling in the brain using two-photon microscopy. These data show the feasibility of making gene knockout cephalopod lines that can be used for live imaging of neural activity in these behaviorally sophisticated organisms.

  View details for DOI 10.1016/j.cub.2023.05.066

  View details for PubMedID 37343558

• Topological supramolecular network enabled high-conductivity, stretchable organic bioelectronics. Science (New York, N.Y.) Jiang, Y., Zhang, Z., Wang, Y. X., Li, D., Coen, C. T., Hwaun, E., Chen, G., Wu, H. C., Zhong, D., Niu, S., Wang, W., Saberi, A., Lai, J. C., Wu, Y., Wang, Y., Trotsyuk, A. A., Loh, K. Y., Shih, C. C., Xu, W., Liang, K., Zhang, K., Bai, Y., Gurusankar, G., Hu, W., Jia, W., Cheng, Z., Dauskardt, R. H., Gurtner, G. C., Tok, J. B., Deisseroth, K., Soltesz, I., Bao, Z. 2022; 375 (6587): 1411-1417

  Abstract

  Intrinsically stretchable bioelectronic devices based on soft and conducting organic materials have been regarded as the ideal interface for seamless and biocompatible integration with the human body. A remaining challenge is to combine high mechanical robustness with good electrical conduction, especially when patterned at small feature sizes. We develop a molecular engineering strategy based on a topological supramolecular network, which allows for the decoupling of competing effects from multiple molecular building blocks to meet complex requirements. We obtained simultaneously high conductivity and crack-onset strain in a physiological environment, with direct photopatternability down to the cellular scale. We further collected stable electromyography signals on soft and malleable octopus and performed localized neuromodulation down to single-nucleus precision for controlling organ-specific activities through the delicate brainstem.

  View details for DOI 10.1126/science.abj7564

  View details for PubMedID 35324282

• Recruitment and inhibitory action of hippocampal axo-axonic cells during behavior. Neuron Dudok, B., Szoboszlay, M., Paul, A., Klein, P. M., Liao, Z., Hwaun, E., Szabo, G. G., Geiller, T., Vancura, B., Wang, B., McKenzie, S., Homidan, J., Klaver, L. M., English, D. F., Huang, Z. J., Buzsaki, G., Losonczy, A., Soltesz, I. 2021

  Abstract

  The axon initial segment of hippocampal pyramidal cells is a key subcellular compartment for action potential generation, under GABAergic control by the "chandelier" or axo-axonic cells (AACs). Although AACs are the only cellular source of GABA targeting the initial segment, their invivo activity patterns and influence over pyramidal cell dynamics are not well understood. We achieved cell-type-specific genetic access to AACs in mice and show that AACs in the hippocampal area CA1 are synchronously activated by episodes of locomotion or whisking during rest. Bidirectional intervention experiments in head-restrained mice performing a random foraging task revealed that AACs inhibit CA1 pyramidal cells, indicating that the effect of GABA on the initial segments in the hippocampus is inhibitory invivo. Finally, optogenetic inhibition of AACs at specific track locations induced remapping of pyramidal cell place fields. These results demonstrate brain-state-specific dynamics of a critical inhibitory controller of cortical circuits.

  View details for DOI 10.1016/j.neuron.2021.09.033

  View details for PubMedID 34648750

• Alternating sources of perisomatic inhibition during behavior. Neuron Dudok, B., Klein, P. M., Hwaun, E., Lee, B. R., Yao, Z., Fong, O., Bowler, J. C., Terada, S., Sparks, F. T., Szabo, G. G., Farrell, J. S., Berg, J., Daigle, T. L., Tasic, B., Dimidschstein, J., Fishell, G., Losonczy, A., Zeng, H., Soltesz, I. 2021

  Abstract

  Interneurons expressing cholecystokinin (CCK) and parvalbumin (PV) constitute two key GABAergic controllers of hippocampal pyramidal cell output. Although the temporally precise and millisecond-scale inhibitory regulation of neuronal ensembles delivered by PV interneurons is well established, the invivo recruitment patterns of CCK-expressing basket cell (BC) populations has remained unknown. We show in the CA1 of the mouse hippocampus that the activity of CCK BCs inversely scales with both PV and pyramidal cell activity at the behaviorally relevant timescales of seconds. Intervention experiments indicated that the inverse coupling of CCK and PV GABAergic systems arises through a mechanism involving powerful inhibitory control of CCK BCs by PV cells. The tightly coupled complementarity of two key microcircuit regulatory modules demonstrates a novel form of brain-state-specific segregation of inhibition during spontaneous behavior.

  View details for DOI 10.1016/j.neuron.2021.01.003

  View details for PubMedID 33529646

• Supramammillary regulation of locomotion and hippocampal activity. Science (New York, N.Y.) Farrell, J. S., Lovett-Barron, M., Klein, P. M., Sparks, F. T., Gschwind, T., Ortiz, A. L., Ahanonu, B., Bradbury, S., Terada, S., Oijala, M., Hwaun, E., Dudok, B., Szabo, G., Schnitzer, M. J., Deisseroth, K., Losonczy, A., Soltesz, I. 2021; 374 (6574): 1492-1496

  Abstract

  [Figure: see text].

  View details for DOI 10.1126/science.abh4272

  View details for PubMedID 34914519