Effects Of Tris(1,3-dichloro-2-propyl) Phosphate Of Environmental Concentrations On Intestinal Structure And Microbial Community Of Zebrafish

Tris(1,3-dichloroisopropyl)phosphate(TDCIPP)is a synthetic organic phosphorus flame retardant,which has been widely used in recent years and widely exists in the water environment.TDCIPP exposure could cause reproductive toxicity,growth toxicity and neurotoxicity in zebrafish,but its effect on the zebrafish intestine was unknown.In recent years,more and more studies have shown that chemical exposure will cause fish intestinal damage and intestinal microorganism changes,and intestinal health and intestinal microorganisms of fish are closely related to life activities such as fish growth,development and reproduction.The results of previous research in our laboratory showed that the environmental dose of TDCIPP could significantly reduce the body length and weight of zebrafish and inhibite the growth and development of zebrafish.In this experiment,the effect of environmental dose TDCIPP on the intestinal health and intestinal flora of zebrafish was investigated,and the possible mechanism of growth and development toxicity of TDCIPP was explored.1.Zebrafish embryos were exposed to environmental doses(0,30,300,and 3000ng/L)of TDCIPP for 3 months,and their effects on growth were examined.HE(Hematoxylin-eosin staining)was used to observe intestinal sections,and we measured intestinal oxidative stress levels(oxide dismutase(SOD),catalase(CAT),glutathione(GSH)and glutathione peroxidase(GPx)),serotonin(5-HT),tight junction protein ZO-2(TJP2),ethoxyisoprene-O-deethylase(EROD)and interleukin-1?(IL-1?)levels to assess TDCIPP exposure on zebras Impact of fish intestinal health.The results showed that TDCIPP significantly reduced the body weight and body length of females,but had no significant effect on males.At the same time,the intestinal damage of female zebrafish increased with the increase of exposure concentration.Including injury,rupture and even shedding of the intestinal villi apex,significant decrease of TJP2 content and significant increase of EROD activity,but no significant change in males except for GPx.Our resultssuggested that exposure to TDCIPP led to intestinal damage and inhibition of female growth in zebrafish.2.16 s rRNA gene sequencing was used to detect the effect of TDCIPP exposure on zebrafish intestinal microorganisms,and further explored the relationship among intestinal physiological indicators,growth indicators and intestinal flora.TDCIPP exposure significantly increased the species richness and Alpha diversity of the intestinal flora of male zebrafish,but there was no significant change in females.Increased diversity of gut flora in the gut of male fish that might be a self-protection mechanism for male fish from gut damage.Further analysis revealed that TDCIPP exposure increased pathogenic bacteria(Legionella and Flavobacterium)in the gut of female fish.Correlation analysis showed that Legionella genus and body length had a significant negative correlation.It indicates that TDCIPP might inhibit the growth and development of female fish by affecting the composition of intestinal colonies.