Research presented in the PLOS Biology journal suggests that microorganisms have a substantial impact on the social development of zebrafish, influencing the neural pruning process in the brain as it develops. If microbiota is missing in the early stages of development, social behavior is hindered and neural connections become more dense. However, introducing intestinal bacteria can rectify this, underlining the vital role of microbiota in neural pruning and social behavior in zebrafish larvae.
Germ-free larvae showed alterations in neural connections due to diminished pruning by immune cells.
A team led by Joseph Bruckner at the University of Oregon, US, has published a study in the open access journal PLOS Biology. The study reveals that microorganisms play a crucial part in the normal social development of zebrafish by affecting the pruning of neural connections in the brain as it develops.
Zebrafish larvae’s transparent skin allows scientists to observe neural development closely. The team conducted several experiments exploring the neuronal and social development of zebrafish larvae raised either with or without their typical microbiota during the first week of development.
Their findings suggest that the early absence of microbes impedes the social behavior of larval zebrafish at 14 days, even if their normal microbiota is reintroduced a week prior. Compared to larvae with normal microbiota, the brains of these germ-free larvae had fewer microglia (immune cells) in their forebrains and showed denser, more intricate neural branching. Single-cell RNA sequencing showed these microglia also had reduced levels of complement c1q, a gene involved in the pruning of neural connections known as synapses.
In a genetic experiment, reducing the microglia without affecting the microbiota had a similar outcome, increasing neural density and branching relative to controls. Normal neural and social development was re-established in germ-free larvae by introducing various bacterial groups native to the zebrafish intestine. This shows that the pruning activity of microglia is influenced by common features across many types of bacteria.
The study is the first of its kind to confirm that microglia are necessary for neural connection pruning in zebrafish larvae, and that an intact microbiota is critical for normal pruning and fish social behavior. The findings also highlight a crucial developmental window during the first week of larval development when the microbiota stimulates microglial localization to the forebrain to prune neural connections.
Eisen notes, “Studying zebrafish social interactions gives us insights into how essential social interactions are for both animals and humans. We found that symbiotic bacteria boost social behavior by enhancing the ability of microglia, the brain’s immune cells, to remodel recognized ‘social’ neurons in the zebrafish brain.”
For further information on this study, refer to Researchers Uncover a Gut-Brain Connection for Social Development.
Reference: “The microbiota promotes social behavior by modulating microglial remodeling of forebrain neurons” by Joseph J. Bruckner, Sarah J. Stednitz, Max Z. Grice, Dana Zaidan, Michelle S. Massaquoi, Johannes Larsch, Alexandra Tallafuss, Karen Guillemin, Philip Washbourne and Judith S. Eisen, 1 November 2022, PLOS Biology. DOI: 10.1371/journal.pbio.3001838
I accept the use of Google Analytics and related cookies across the TrendMD network (widget, website, blog). Learn more. Yes or No?
Table of Contents
Frequently Asked Questions (FAQs) about Gut Microbiota and Social Behavior in Zebrafish
What is the main finding of the study published in PLOS Biology about zebrafish?
The study suggests that gut microorganisms play a significant role in the social development of zebrafish by influencing the neural pruning process in the developing brain. An early absence of these microorganisms can lead to hindered social behavior and denser neural connections, but reintroducing intestinal bacteria can restore normal development.
How did the researchers observe the social development of the zebrafish?
The researchers utilized the unique characteristic of zebrafish larvae’s transparent skin to observe their neuronal development. They conducted a series of experiments comparing the development of zebrafish larvae raised with and without their normal microbiota during the first week of their lives.
What are the effects of an early absence of microbes on zebrafish larvae?
Early absence of microbes was found to inhibit the social behavior of zebrafish larvae. These germ-free larvae had fewer immune cells known as microglia in their forebrains and exhibited denser, more complex neural branching patterns compared to their counterparts with normal microbiota.
How does the gut microbiota influence the neural development of zebrafish?
According to the study, the gut microbiota appears to affect the pruning of neural connections in the developing brain of zebrafish. The findings also suggest that microglia, immune cells in the brain, require a fully functioning microbiota to prune these neural connections effectively.
What does the study suggest about the relationship between microglia and gut microbiota in zebrafish?
The study shows that reducing the number of microglia genetically (without affecting the gut microbiota) leads to increased neural density and branching – a result similar to what is seen in germ-free zebrafish larvae. This indicates that the pruning activity of microglia is influenced by the presence of gut microbiota. Moreover, the introduction of various bacterial groups native to the zebrafish intestine was able to restore normal neural and social development in germ-free larvae.
More about Gut Microbiota and Social Behavior in Zebrafish
- Original PLOS Biology article
- Zebrafish social behavior: an overview of studies and implications
- Impact of gut microbiota on neurological development and behavior
- Understanding neural pruning
5 comments
wow, thats some complex science right there. who knew fish and bacteria had such a close relationship??
Amazing work by these researchers. It’s mindblowing to see how gut bacteria can influence social behavior…in a fish!
never thought id say this but, Go science! Shows us just how interconnected life really is.
The detail about neural pruning is particularly fascinating. Never knew microbiota had a role in it. Can’t wait to read more about this.
Love zebrafish, never knew they had such a complex biology. Wonder if this applies to other species too?