Image velocimetry and spectral analysis enable quantitative characterization of larval zebrafish gut motility

Ganz, Julia; Baker, Ryan; Hamilton, M. Kristina; Melançon, Ellie; Diba, Parham; Eisen, Judith S; Parthasarathy, Raghuveer

doi:10.1111/nmo.13351

Cited by 35 publications

(51 citation statements)

References 43 publications

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“…To test this expulsion-based mechanism more directly, we assessed whether the abundance of Δmot and Δche could be rescued in ret −/− mutant zebrafish hosts, which have reduced intestinal transport because of a dysfunctional enteric nervous system [32,42]. Humans with ret mutations can develop Hirschsprung disease, which is an affliction characterized by intestinal dysmotility and altered gut microbiome composition [43,44].…”

Section: Plos Biologymentioning

confidence: 99%

“…Zebrafish lines used in this study included: University of Oregon stock wild-type ABCxTU; zebrafish carrying the ret1 hu2846 mutant allele [32,42]; zebrafish carrying the Tg(tnfa:GFP) transgene [45]; and zebrafish carrying the Tg(mpeg1:mCherry) transgene [46]. Double transgenic animals included Tg(tnfa:GFP) x Tg(mpeg1:mCherry) and Tg(tnfa:GFP) x Tg(mpx:mCherry) [67].…”

Section: Zebrafish Linesmentioning

confidence: 99%

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Swimming motility of a gut bacterial symbiont promotes resistance to intestinal expulsion and enhances inflammation

et al. 2020

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Some of the densest microbial ecosystems in nature thrive within the intestines of humans and other animals. To protect mucosal tissues and maintain immune tolerance, animal hosts actively sequester bacteria within the intestinal lumen. In response, numerous bacterial pathogens and pathobionts have evolved strategies to subvert spatial restrictions, thereby undermining immune homeostasis. However, in many cases, it is unclear how escaping host spatial control benefits gut bacteria and how changes in intestinal biogeography are connected to inflammation. A better understanding of these processes could uncover new targets for treating microbiome-mediated inflammatory diseases. To this end, we investigated the spatial organization and dynamics of bacterial populations within the intestine using larval zebrafish and live imaging. We discovered that a proinflammatory Vibrio symbiont native to zebrafish governs its own spatial organization using swimming motility and chemotaxis. Surprisingly, we found that Vibrio's motile behavior does not enhance its growth rate but rather promotes its persistence by enabling it to counter intestinal flow. In contrast, Vibrio mutants lacking motility traits surrender to host spatial control, becoming aggregated and entrapped within the lumen. Consequently, nonmotile and nonchemotactic mutants are susceptible to intestinal expulsion and experience large fluctuations in absolute abundance. Further, we found that motile Vibrio cells induce expression of the proinflammatory cytokine tumor necrosis factor alpha (TNFα) in gut-associated macrophages and the liver. Using inducible genetic switches, we demonstrate that swimming motility can be manipulated in situ to modulate the spatial organization, persistence, and inflammatory activity of gut bacterial populations. Together, our findings suggest that host spatial control over resident microbiota plays a broader role in regulating the abundance and persistence of gut bacteria than simply protecting mucosal tissues. Moreover, we show that intestinal flow and bacterial motility are potential targets for therapeutically managing bacterial spatial organization and inflammatory activity within the gut. PLOS BIOLOGYPLOS Biology | https://doi.

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Section: Plos Biologymentioning

confidence: 99%

Section: Zebrafish Linesmentioning

confidence: 99%

Swimming motility of a gut bacterial symbiont promotes resistance to intestinal expulsion and enhances inflammation

et al. 2020

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“…During this developmental stage, until roughly 7 days post-fertilization, larvae need not be fed and are sustained on yolk-derived nutrients, enabling maintenance under gnotobiotic conditions. The larval intestine is, however, highly active beginning at 3.5 days (25) and exhibits a range of motility patterns, including coordinated peristalsis-like movements that are controlled by the enteric nervous system and can act on resident bacteria (14,26). After the colonization period, three-dimensional image stacks were acquired using a custom-built light sheet fluorescence microscope described in detail elsewhere (12).…”

Section: Experimental Designmentioning

confidence: 99%

Bacterial Cohesion Predicts Spatial Distribution in the Larval Zebrafish Intestine

Schlomann

Wiles

Wall

et al. 2018

Biophysical Journal

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Are there general biophysical relationships governing the spatial organization of the gut microbiome? Despite growing realization that spatial structure is important for population stability, interbacterial competition, and host functions, it is unclear in any animal gut whether such structure is subject to predictive, unifying rules or if it results from contextual, species-specific behaviors. To explore this, we used light sheet fluorescence microscopy to conduct a high-resolution comparative study of bacterial distribution patterns throughout the entire intestinal volume of live, larval zebrafish. Fluorescently tagged strains of seven bacterial symbionts, representing six different species native to zebrafish, were each separately monoassociated with animals that had been raised initially germ-free. The strains showed large differences in both cohesion-the degree to which they auto-aggregate-and spatial distribution. We uncovered a striking correlation between each strain's mean position and its cohesion, whether quantified as the fraction of cells existing as planktonic individuals, the average aggregate size, or the total number of aggregates. Moreover, these correlations held within species as well; aggregates of different sizes localized as predicted from the pan-species observations. Together, our findings indicate that bacteria within the zebrafish intestine are subject to generic processes that organize populations by their cohesive properties. The likely drivers of this relationship-peristaltic fluid flow, tubular anatomy, and bacterial growth and aggregation kinetics-are common throughout animals. We therefore suggest that the framework introduced here of biophysical links between bacterial cohesion and spatial organization should be useful for directing explorations in other host-microbe systems, formulating detailed models that can quantitatively map onto experimental data, and developing new tools that manipulate cohesion to engineer microbiome function.

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“…We provide both a qualitative and a quantitative description of the relevant dynamics, beginning with the following conceptual model: single cells of Enterobacter replicate to form small clusters, which then aggregate to form larger clusters under the influence of intestinal flow. Large clusters are transported by the rhythmic contractions of the gut [8, 7, 14] and stochastically expelled from the host [8, 7]. The individual bacteria and small clusters that remain within the intestine serve as a reservoir that reseeds the next population, and the process of replication, aggregation, and expulsion repeats.…”

Section: Introductionmentioning

confidence: 99%

Low-dose antibiotics can collapse gut bacterial populations via a gelation transition

Schlomann

Wiles

Wall

et al. 2019

Preprint

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Antibiotics can profoundly alter the intestinal microbiome even at the sublethal concentrations often encountered through environmental contamination. The mechanisms by which low-dose antibiotics induce large yet highly variable changes in gut communities have remained elusive. We therefore investigated the impact of antibiotics on intestinal bacteria using larval zebrafish, whose experimental tractability enables high-resolution in vivo examination of response dynamics. Live imaging revealed that sublethal doses of the common antibiotic ciprofloxacin lead to severe drops in bacterial abundance, coincident with changes in spatial organization that increase susceptibility to intestinal expulsion. Strikingly, our data can be mapped onto a physical model of living gels that links bacterial aggregation and expulsion to nonequilibrium abundance dynamics, providing a framework for predicting the impact of antibiotics on the intestinal microbiome.2 1 inhibitory levels of many bacteria, antibiotics can lead to major and highly variable changes 3 in the gut microbiome through mechanisms that remain mysterious [2, 3, 4]. Sublethal 4 antibiotics can also significantly alter animal physiology, a well-known example being the 5 intentional growth enhancement of livestock, possibly through pathways mediated by the 6 microbiome [2]. Low concentrations of antibiotics are often present in the environment as 7 byproducts of unchecked agricultural and biomedical use, generating public health concerns 8 associated with the emergence of drug resistance [5] as well as more direct impacts on human 9 health [6]. It is therefore crucial to uncover the mechanisms by which sublethal antibiotics 10 can reshape gut microbial communities. Understanding which particular bacterial strains are 11 resilient or susceptible to antibiotic perturbations will allow us to predict the consequences 12 of environmental contamination and harness antibiotics as a therapeutic tool for reshaping 13 gut communities. 14 In vitro studies have shown that low-dose antibiotics can induce major morphological and 15 behavioral changes in bacteria. In particular, they can promote a transition to a more 16 aggregated growth mode marked by reduced flagellar motility, reduced division rates, and 17 increased formation of adherent biofilms [5]. We therefore hypothesized that changes in the 18 physical structure of intestinal bacterial populations play a major role in determining antibi-19 otic response dynamics. This notion is supported by our previous work showing that natural 20 bacterial aggregates are highly susceptible to intestinal transport driven by the propulsive 21 forces within the vertebrate gut. For example, imaging-based studies in larval zebrafish have 22 revealed that human-derived Vibrio cholerae can use its Type VI Secretion System to en-23 hance intestinal contractions and dispel aggregated resident bacteria [7]; that disruption of 24 transport by perturbation of the enteric nervous system can neutralize inter-bacterial compe-25 tition [8]; and that the...

show abstract

Image velocimetry and spectral analysis enable quantitative characterization of larval zebrafish gut motility

Abstract: Our image analysis approach enables insights into gut dynamics in a wide variety of developmental and physiological contexts and can also be extended to analyze other types of cell movements.

Cited by 35 publications

References 43 publications

Swimming motility of a gut bacterial symbiont promotes resistance to intestinal expulsion and enhances inflammation

Swimming motility of a gut bacterial symbiont promotes resistance to intestinal expulsion and enhances inflammation

Bacterial Cohesion Predicts Spatial Distribution in the Larval Zebrafish Intestine

Low-dose antibiotics can collapse gut bacterial populations via a gelation transition

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