Microfluidics for electrophysiology, imaging, and behavioral analysis of<i>Hydra</i>

Badhiwala, Krishna N.; Gonzales, D.; Vercosa, Daniel G.; Avants, Benjamin W.; Robinson, Jacob T.

doi:10.1039/c8lc00475g

Cited by 32 publications

(34 citation statements)

References 88 publications

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“…Whenever one introduces a new tool, it is important to compare performance with existing methods and demonstrate that the advantages of the new tool are sufficient to make its adoption worthwhile. While anesthetics were and continue to be most frequently used to relax Hydra prior to fixation for histological and immunohistochemistry studies (Hausman & Burnett 1971; Benos et al 1977; Münder et al 2013; Buzgariu et al 2018), the advent of modern molecular tools have brought with it an increased use for in vivo applications (Takahashi & Hamaue 2010; Badhiwala et al 2018; Lommel et al 2017). Table 1 provides an overview of the various anesthetics that have been reported in the literature for use in Hydra and examples of their respective applications.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, a reversible way of slowing or preventing the animal’s movements would greatly facilitate a wide range of experiments. The search for a reliable and reversible relaxant in Hydra has driven the field to try an array of compounds, with the most prominent ones being urethane (Macklin 1976; Benos et al 1977; Münder et al 2013; Takahashi & Hamaue 2010; Buzgariu et al 2018), heptanol (Smith et al 2000; Rentzsch et al 2005), and chloretone (Badhiwala et al 2018; Lommel et al 2017; Loomis 1955; Kepner & Hopkins 1938). Urethane and heptanol have broad effects on Hydra.…”

Section: Introductionmentioning

confidence: 99%

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Linalool acts as a fast and reversible anesthetic inHydra

Goel

Wang

Martin

et al. 2019

Preprint

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15The ability to make transgenic Hydra lines has opened the door for quantitative in vivo studies of 16 Hydra regeneration and physiology. These studies commonly include excision, grafting and 17 transplantation experiments along with high-resolution imaging of live animals, which can be 18 challenging due to the animal's response to touch and light stimuli. While various anesthetics 19 have been used in Hydra studies over the years, they tend to be toxic over the course of a few 20 hours or their long-term effects on animal health have not been studied. Here we show that the 21 monoterpenoid linalool is a useful anesthetic for Hydra. Linalool is easy to use, non-toxic, fast 22 acting, and reversible. It has no detectable long-term effects on cell viability or cell proliferation. 23 We demonstrate that the same animal can be immobilized in linalool multiple times at intervals 24 of several hours for repeated imaging over 2-3 days. This uniquely allows for in vivo imaging of 25 dynamic processes such as head regeneration. We further directly compare linalool to currently 26 used anesthetics and show its superior performance. Because linalool, which is frequently 27 utilized in perfumes and cosmetic products, is also non-hazardous to humans, it will be a useful 28 tool for Hydra research in both research and teaching contexts. 29 30 31 112

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Linalool acts as a fast and reversible anesthetic inHydra

Goel

Wang

Martin

et al. 2019

Preprint

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“…In addition, the availability of markers specific to neuronal subtypes will enable precise alterations to neural circuits. Nervous system function in such engineered animals can be tested using newly developed microfluidic tools that allow for simultaneous electrical and optical recordings in behaving animals (84).…”

Section: Discussionmentioning

confidence: 99%

Stem cell differentiation trajectories inHydraresolved at single-cell resolution

Siebert

Farrell

Cazet

et al. 2018

Preprint

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The adult Hydra polyp continuously renews all of its cells using three separate stem cell populations, but the genetic pathways enabling homeostatic tissue maintenance are not well understood. We used Drop-seq to sequence transcriptomes of 24,985 single Hydra cells and identified the molecular signatures of a broad spectrum of cell states, from stem cells to terminally differentiated cells. We constructed differentiation trajectories for each cell lineage and identified the transcription factors expressed along these trajectories, thus creating a comprehensive molecular map of all developmental lineages in the adult animal. We unexpectedly found that neuron and gland cell differentiation transits through a common progenitor state, suggesting a shared evolutionary history for these secretory cell types. Finally, we have built the first gene expression map of the Hydra nervous system. By producing a comprehensive molecular description of the adult Hydra polyp, we have generated a resource for addressing fundamental questions regarding the evolution of developmental processes and nervous system function.

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“…By separating Hydra from fluid flow, the animal can be rapidly heated/cooled (by flowing water at controlled temperatures through the bottom stimulus flow channels) without undesired mechanical stimulation from high flow rates (avoided due to the glass coverslip separation). To construct the double layer chip, we first fabricated the top immobilization layer by molding PDMS from a master mold adapted from a 2 mm diameter x 100 μm tall chemical perfusion chip (designed as previously described) [31]. Briefly, a circular observation chamber designed specifically for Hydra was patterned using soft lithography on a silicon substrate, and a ~5mm thick layer of PDMS was molded from this master mold.…”

Section: Microfluidic Device Fabricationmentioning

confidence: 99%

“…Volumetric imaging was performed using a confocal microscope (Nikon TI Eclipse) with animals immobilized in chemical perfusion microfluidic chips (see Badhiwala et al [31]) and chemically paralyzed with 1:5000 linalool. Animals were imaged three times a week (one day after the control animals were fed) over two weeks.…”

Section: Longitudinal Imaging Of the Entire Nervous Systemmentioning

confidence: 99%

Stable behavioral and neural responses to thermal stimulation despite large changes in theHydra vulgarisnervous system

Tzouanas

et al. 2019

Preprint

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Nervous systems are remarkable for supporting stable animal behavior despite dramatic changes to neurons' number and connectivity. An ideal model organism to study this phenomenon would have: 1) dynamic neural architecture 2) transgenic reporters of neural activity, 3) a small, transparent body, and 4) well-defined sensory-motor behaviors. While Hydra vulgaris possesses the first three advantages, it currently lacks well-characterized sensory-motor responses. Here, we show the first quantitative measurements of Hydra's behavioral responses to thermal stimulation and associated neural activity.Specifically, we find that Hydra elongate and then contract when heated. This behavior is accompanied by synchronous, periodic activity of neurons in the animal's peduncle. We find that the frequency of these neural oscillations is nearly the same even if the number of neurons change by a factor of two.These observations suggest that Hydra provides a rich model for studying how animals maintain stable sensory-motor responses within dynamic neural circuit architectures.One sentence summary: Here we show that Hydra have a group of thermally responsive neurons that encodes the absolute temperature of a thermal stimulus and that this encoding is independent of the number of neurons in the animal.

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Microfluidics for electrophysiology, imaging, and behavioral analysis ofHydra

Abstract: Microfluidic devices allow scalable and customizable solutions for multi-modal interrogation of these soft, deformable Hydra.

Cited by 32 publications

References 88 publications

Linalool acts as a fast and reversible anesthetic inHydra

Linalool acts as a fast and reversible anesthetic inHydra

Stem cell differentiation trajectories inHydraresolved at single-cell resolution

Stable behavioral and neural responses to thermal stimulation despite large changes in theHydra vulgarisnervous system

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