The Presence or Absence of Intestinal Microbiota Affects Lipid Deposition and Related Genes Expression in Zebrafish (Danio rerio)

Abstract

Understanding how intestinal microbiota alters energy homeostasis and lipid metabolism is a critical process in energy balance and health. However, the exact role of intestinal microbiota in the regulation of lipid metabolism in fish remains unclear. Here, we used two zebrafish models (germ-free and antibiotics-treated zebrafish) to identify the role of intestinal microbiota in lipid metabolism. Conventional and germ-free zebrafish larvae were fed with egg yolk. Transmission electron microscopy was used to detect the presence of lipid droplets in the intestinal epithelium. The results showed that, microbiota increased lipid accumulation in the intestinal epithelium. The mRNA sequencing technology was used to assess genes expression level. We found majority of the differentially expressed genes were related to lipid metabolism. Due to the limitation of germ-free zebrafish larvae, antibiotics-treated zebrafish were also used to identify the relationship between the gut microbiota and the host lipid metabolism. Oil-red staining showed antibiotics-treated zebrafish had less intestinal lipid accumulation than control group. The mRNA expression of genes related to lipid metabolism in liver and intestine was also quantified by using real-time PCR. The results indicated that apoa4, hsl, cox15, slc2a1a, and lss were more related to intestinal bacteria in fish, while the influence of intestinal microbiota on the activity of fabp6, acsl5, cd36, and gpat2 was different between the liver and intestine. This study identified several genes regulated by intestinal microbiota. Furthermore, the advantages and disadvantages of each model have been discussed. This study provides valuable information for exploring host-microbiota interactions in zebrafish in future.

Intestinal microbiota lipid metabolism varies across rainbow trout (Oncorhynchus mykiss ) phylogeographic divide

“…We postulate that the observed differences in lipid metabolism across this phylogeographic divide results from an increased ability of eastern Cascade fish to absorb and utilize dietary lipids compared to western Cascade fish due to host genetic differences controlling microbiota content. Recent studies using germ-free zebrafish have noted differences in gene expression of lipid deposition genes based on microbiota composition, but did not evaluate whether or not these differences also occur on a strain-specific basis (Sheng et al 2018). Should our finding be validated by additional studies that indicate differences in muscle lipid content are present across this divide it has significant implications for understanding co-evolutionary processes, commercial fishing industry improvement and aquaculture.…”

“…A comparative study of germ‐free and conventionally reared zebrafish showed genes associated with lipid absorption and biosynthesis upregulated in control groups (Sheng et al . ). Additionally, the term ‘metagenome’ describes the combination of host genes and the genes present in trillions of gut microbes that colonize vertebrates, with the vast majority inhabiting the distal gut.…”

“…Recent studies using germ‐free zebrafish have noted differences in gene expression of lipid deposition genes based on microbiota composition, but did not evaluate whether or not these differences also occur on a strain‐specific basis (Sheng et al . ). Should our finding be validated by additional studies that indicate differences in muscle lipid content are present across this divide it has significant implications for understanding co‐evolutionary processes, commercial fishing industry improvement and aquaculture.…”

“…Most believe the interactions are mutualistic, as exemplified by bacteria known to help host organisms acquire nutrients and intestinal microbiota that increase lipid bioavailability in host intestinal epithelium and liver (Semova et al 2012;Sullam et al 2012). A comparative study of germfree and conventionally reared zebrafish showed genes associated with lipid absorption and biosynthesis upregulated in control groups (Sheng et al 2018). Additionally, the term 'metagenome' describes the combination of host genes and the genes present in trillions of gut microbes that colonize vertebrates, with the vast majority inhabiting the distal gut.…”

The effect of acyl-CoA synthetase long-chain family member 5 on triglyceride synthesis in bovine preadipocytes

“…Bu et al (2010) conducted a series of trials in which knockdown ACSL5 could decrease hepatic secretion in neutral lipid synthesis (Bu and Mashek, 2010). The activity of ACSL5 could affect intestinal microbial relationships and affect lipid metabolism further (Sheng et al, 2018). Overall, the above studies indicate that ACSL5 plays an important role in the fat metabolism pathway of mammalian animals.…”