Assessing The Impact Of Wastewater From The Ta Lai Fabric And Brocade Craft Village, Tan Phu District, Dong Nai Province, On The Development And Gene Expression In Zebrafish (Danio Rerio)

Abstract

Wastewater from traditional dyeing and weaving craft villages is a complex pollution source, containing both organic matter and heavy metals, but comprehensive assessments of their toxicity remain limited. This study aimed to systematically evaluate the impact of wastewater from the Ta Lai craft village (Tan Phu, Dong Nai) on the development, heavy metal accumulation, and molecular-level responses in zebrafish (Danio rerio). Zebrafish embryos were exposed to different concentrations of wastewater (0%, 25%, 50%, 75%, 100%) from the 1-2 cell stage until 7 days post fertilization (dpf). Hatching rate, malformation rate, heart rate, and body length were monitored. Heavy metal content accumulated in larvae was quantified by ICP-MS. The expression of genes related to oxidative stress (sod1, sod2), metal detoxification (mt1, mt2), and cell cycle (cdk4, cdk6) was analyzed by RT-qPCR. The wastewater was slightly acidic (pH=5.8) and contained levels of COD (485 mg/L), BOD (285 mg/L), Chromium (2.85 mg/L), and Lead (1.20 mg/L) exceeding permissible limits. Wastewater exposure inhibited the hatching rate (only 10.5% at 100% concentration), drastically increased the malformation rate (95.8%), caused heart rate irregularities, and reduced larval body length in a concentration-dependent manner. Analysis showed significant bioaccumulation of Chromium (45.2 ng/g) and Lead (18.6 ng/g) in larval bodies. At the molecular level, the expression of sod1, sod2, mt1, and mt2 genes was strongly upregulated (from 4.5 to 7.1 fold), while the expression of cdk4 and cdk6 was suppressed (only 0.35 and 0.28 fold, respectively). Wastewater from the Ta Lai craft village causes severe developmental toxicity, leads to heavy metal accumulation, and induces molecular disorders in zebrafish. These results provide crucial scientific evidence highlighting the necessity for effective wastewater treatment measures before discharge to protect aquatic ecosystems and public health.