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Zebrafish larvae require specific strains of bacteria to allow for normal neurobehavioral development.
Citation:
Kvasnicka, A., D. Phelps, T. Catron, N. Brinkman, S. Keely, E. Anneken, C. Wood, AND T. Tal. Zebrafish larvae require specific strains of bacteria to allow for normal neurobehavioral development. NCSOT, RTP, NC, October 30, 2017.
Impact/Purpose:
Intestinal microbes are thought to influence mood, anxiety, and increasingly, brain development. To determine the role of microbiota in zebrafish nervous system development, we used axenic (microbe-free) zebrafish and axenic zebrafish colonized on day 1 with either a diverse mixture of bacteria harvested from an aquaculture facility or with single strains of bacteria isolated from 10 day old zebrafish. A standard locomotor behavioral assay was used as a functional readout of the microbiota-gut-brain axis. This study showed that axenic zebrafish colonized with single strains of Actinetobacter, Comamonas, or Comamonadaceae develop a normal behavioral phenotype at 10 days of life. We also showed that colonization with a single strain of Vibrio resulted in abnormal behavioral development. This finding replicates an earlier observation we made with another strain of Vibrio (Phelps et al. Scientific Reports. 2017.). It is currently unknown whether and how microbiota might influence the developmental neurotoxicity of environmental chemicals. These data raise the possibility that environmental chemicals that target microbiota may harbor the ability to select for microbes that allow for abnormal behavioral development.
Description:
There is an increasing appreciation of the relationship between gut microbiota and nervous system development and function. We previously showed that axenic (microbe-free) larvae are hyperactive at 10 days post fertilization (dpf), relative to colonized zebrafish larvae. Interestingly, while exposure to heat-killed bacteria or microbe associated molecular patterns failed to block hyperactivity in axenic larvae, colonization of axenic larvae with Aeromonas veronii or Vibrio cholerae produced locomotor hypoactivity relative to colonized controls. These data suggest that there is a developmental requirement for certain types of microbes in order to generate normal behavior. To address this hypothesis, eight bacterial isolates were obtained from 10 dpf conventionally colonized zebrafish larvae. 16S rRNA gene sequencing identified four unique isolates: Actinetobacter, Vibrio, Comamonas, and Comamonadaceae. Colonization of axenic embryos on day 1 with 100 cells/mL of Actinobacter, Comamonas, or Comamonadaceae resulted in normal behavioral profiles that were identical to colonized control larvae at 8 dpf. In comparison, axenic embryos colonized with Vibrio bacteria were hypoactive relative to control larvae. Vibrio-related hypoactivity was prevented in axenic larvae colonized with 25 cells/mL each of Actinetobacter, Vibrio, Comamonas, and Comamonadaceae. Taken together, these data suggest that certain bacterial taxa are sufficient to drive normal neurobehavioral development and that developmental colonization with two different strains of Vibrio resulted in behavioral hypoactivity. These findings raise the possibility that environmental chemicals that target microbiota may harbor the ability to select for microbes that allow for abnormal behavioral development.