Elsevier

Aquatic Toxicology

Volume 235, June 2021, 105838
Aquatic Toxicology

Transcriptomic responses predict the toxic effect of parental co-exposure to dibutyl phthalate and diisobutyl phthalate on the early development of zebrafish offspring

https://doi.org/10.1016/j.aquatox.2021.105838Get rights and content

Highlights

  • l

    Combined exposure of parent fish to DBP and DiBP did not affect zebrafish reproduction

  • l

    Combined exposure of parent fish to DBP and DiBP disturbed early development of zebrafish offspring

  • l

    Combined exposure of parent fish to DBP and DiBP affected three molecular functions in F1 larvae

  • l

    Toxic mechanisms of parental individual and combined exposure were different

Abstract

Dibutyl phthalate (DBP) and diisobutyl phthalate (DiBP) have been reported to exhibit reproductive toxicity in vertebrates. However, the combined effect of DBP and DiBP on offspring of exposed parents remains unclear, especially for aquatic organisms such as fish. The aims of this study were to assess the effects of parental co-exposure to DBP and DiBP on early development of zebrafish offspring, and to explore the potential molecular mechanisms involved. The early developmental indicators and transcriptomic profiles of F1 larvae were examined after parental exposure to DBP, DiBP and their mixtures (Mix) for 30 days. Results showed that parental exposure to DBP and DiBP, alone or in combination, resulted in increased hatchability at 48 hpf and heart rate at 96 hpf, and increased the prevalence of malformations and mortality in F1 larvae. Generalized linear model (GLM) suggested an antagonistic interactive effect between DBP and DiBP on mortality and malformations of F1 larvae. The transcriptomic analysis revealed that the molecular mechanisms of parental co-exposure were different from those of either chemical alone. Disruption of molecular functions involved unfolded protein binding, E-box binding and photoreceptor activity in F1 larvae. These findings provide initial insights in the potential mechanism of action of parental co-exposure to DBP and DiBP.

Introduction

Phthalate esters (PAEs) have been classified as endocrine-disrupting compounds (EDCs) (Xu et al., 2020). PAEs are frequently used in the production of polyvinylchloride (PVC) plastic, cosmetics and food packaging materials. Since PAEs are added to polymers without covalent bonds, they can slowly be released into the environment during production and consumption (Benjamin et al., 2017). Di-n-butyl phthalate (DBP) is one of the common PAEs widely used in the production of resins, polymers and adhesives (Liao et al., 2010). It has been found in surface water, atmosphere, and soil. For example, in surface water of the East London harbor, concentrations of DBP were reported to range between 1.0 and 1028.1 μg L−1 (Fatoki and Noma 2002). In atmospheric particles in the vicinity of Chaohu Lake in China, the detected concentration of DBP ranged from 304-499 pg cm−3 (He et al., 2019). Concentration of DBP in agricultural soils in Shandong Peninsula in China were between 0 and 9.855 mg kg−1 (Li et al., 2016). The United States Environmental Protection Agency (USEPA) and China have listed DBP as a priority controllable hazardous substance due to its toxicity to organisms (Liao et al., 2010). As a result, alternative compounds with similar application characteristics begin to be widely used. Diisobutyl phthalate (DiBP) is an isomer of DBP, which has been used as a substitute for DBP to improve the flexibility and durability of industrial and consumer products. Biomonitoring studies showed that there has been an increase in DiBP exposures in recent years (Yost et al., 2019). In aquatic environments, it has been reported that the concentration of DiBP can reach μg L−1 levels (He et al., 2019).

PAEs can accumulate in aquatic organisms from polluted water and through the food chain. For example, DBP and DiBP have been detected in fish of the Asan Lake of Korea (Lee et al., 2019). It has been found that food fish sold in Hong Kong supermarkets contained 0.16-0.94 μg g−1 wet weight (ww) of DBP and 0.43-2.08 μg/g wet weight of DiBP (Cheng et al., 2013). Moreover, the detected concentration of DBP in wild marine fish from the East China Sea was 78.7 ng g−1 (ww), which is much higher than concentrations reported in wild marine fish from the United States and Canada (Hu et al., 2016). Therefore, considering the accumulation of DBP and DiBP in aquatic organisms, further studies are needed to evaluate their potential risks.

The accumulation of DBP and DiBP in parents may affect the development of offspring. For example, human exposure to DBP during pregnancy was shown to induce abnormal development of germ cells in male offspring (Arbuckle et al., 2016). Moreover, testosterone levels in fetal testes were reduced after maternal exposure of rats to DBP from gestation day (GD) 12-19 (Lehmann et al., 2004). Similar to DBP, exposure of GD 0-21 pregnant mice to DiBP (450 mg kg−1 per day) decreased the testosterone concentrations of serum and testes in offspring (Wang et al., 2017). These studies indicated that DBP and DiBP might undergo maternal transfer to the embryo. Compared to mammals, studies on parental transmission for DBP and DiBP in aquatic organisms are scarce, and the potential adverse effects on fish offspring remain unclear.

In fish, parental transfer of some reproductive toxicants, such as polybrominated diphenyl ethers (PBDEs), bisphenol A (BPA) and organochlorine pesticides (OPs) have been observed to interfere with the developmental of their offspring (Chen et al., 2012; Dong et al., 2018; Peng et al., 2012). PAEs are lipophilic and thus accumulate in lipids. In fact, maternally deposited lipids are important nutrition source for early embryo development of fish offspring, and PAEs can be maternally transferred to the embryo through the yolk (Fraher et al., 2016; Qiu et al., 2019b).

There are a variety of PAE compounds in waters, and aquatic organisms are generally exposed to the mixtures of these compounds. Previous studies have shown that exposure to mixtures of PAEs may result in synergistic, additive, or antagonistic effects on different endpoints in aquatic organisms (Chen et al., 2014; Chen et al., 2015). Furthermore, zebrafish embryos exposed to mixtures of DBP (5 μgL−1 and 500 μg/L) and DEP (5 μg/L and 500 μg/L) for 96h had a reduction of acetylcholinesterase activity embryos, showing their potential for causing neurotoxicity (Xu et al., 2013). Considering DiBP is a substitute for DBP, it is reasonable to assume that there is a simultaneous existence of DBP and DiBP in aquatic environments (Cheng et al., 2013; Lee et al., 2019). However, despite increasing awareness of the combined toxicity of DBP and DiBP, there is limited knowledge about their potential interactions and their parental transfer effect. Therefore, we hypothesise that parental exposure to DBP and DiBP may influence the early development of offspring in fish.

Our previous study suggested that combined exposure to DBP and DiBP exerted potential toxicity to ovaries of adult zebrafish at the molecular level (Chen et al., 2019). In the present study, we further studied the effect of parental co-exposure to DBP and DiBP on early development of zebrafish offspring. Our objectives were to investigate whether parental co-exposure could affect the reproduction of zebrafish and pose adverse effects to the offspring, and to assess the interactive effects between DBP and DiBP, and to reveal the potential toxic mechanisms through transcriptomic analysis.

Section snippets

Chemicals

DBP (CAS#84-74-2, purity > 99%), DiBP (CAS#84-69-5, purity > 99%) and the solvent dimethyl sulfoxide (DMSO) (CAS#67-68-5, purity ≥99.5%) were obtained from Sigma-Aldrich. Analytical grade chemical reagents were used throughout the experiment.

Zebrafish maintenance and exposure

The laboratory animal care and use guidelines released by the National Institutes of Health in China were strictly respected during the experiment. The experiment was authorized by the Animal Protection and Utilization Committee in Jiangsu University

Analysis of DBP and DiBP in exposure solutions and F1 embryos

The measured DBP and DiBP concentrations after exposure solution renewal (T0) were 90.5%-99.9% and 95.0%-98.5% of the nominal concentrations, respectively (Table S3). DBP concentrations in the F1 embryos after parental exposure to 11, 113 and 1133 μg L−1 were 12.7±1.3, 64.9±2.5, 113.8±0.7 ng g−1 wet weight, respectively (Fig. 2). Concentrations of DiBP in the F1 embryos after parental exposure to 10, 103 and 1038 μg L−1 were 9.4±3.1, 53.7±0.5, 99.2±2.3 ng g−1 wet weight, respectively. Measured

Discussion

DBP and DiBP are ubiquitous reproductive toxicants that have caused widespread concern about their potential toxic effects in offspring. In this study, 4-month old zebrafish were used to evaluate the combined effect of parental DBP and DiBP exposure on their reproduction and the early development of their offspring. Data showed that while exposure to the greatest concentrations of the individual compounds significantly inhibited fecundity, no comparable effects occurred when parent fish were

Conclusion

This study demonstrated that parental co-exposure to DBP and DiBP could induce early developmental toxicity of zebrafish offspring. The transcriptomic response analysis based on GO an KEGG revealed that changes of molecular functions involving unfolded protein binding, E-box binding and photoreceptor activity in F1 larvae from parental co-exposure may produce adverse effects on eye development in offspring. Different from F1 larvae from parental co-exposure, the effects on gene transcripts of

Author contributions

Hui Chen: Writing, Conceptualization, Methodology, Software, Investigation, Writing Original Draft, Data Curation

Weiwei Feng: Writing: Review & Editing.

Kun Chen: Validation, Formal analysis, Visualization, Software.

Xuchun Qiu: Validation, Formal analysis, Visualization.

Hai Xu: Resources, Writing - Review & Editing, Supervision

Guanghua Mao: Writing: Review & Editing

Ting Zhao: Writing: Review & Editing

Xiangyang Wu: Resources, Writing - Review & Editing, Supervision, Data Curation.

Liuqing Yang:

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Priority Academic Program Development of Jiangsu Higher Education Institutions and Collaborative Innovation Center of Technology and Material of Water Treatment. This work was financially supported by State Key Laboratory of Environmental Chemistry and Ecotoxicology Open Fund KF 2017-19.

References (54)

  • Y. He et al.

    The occurrence, composition and partitioning of phthalate esters (PAEs) in the water-suspended particulate matter (SPM) system of Lake Chaohu China

    Sci Total Environ.

    (2019)
  • X.L. Hu et al.

    Phthalate monoesters as markers of phthalate contamination in wild marine organisms

    Environ Pollut

    (2016)
  • Y.M. Lee et al.

    Distribution of phthalate esters in air, water, sediments, and fish in the Asan Lake of Korea

    Environ Int

    (2019)
  • K.K. Li et al.

    Distribution of phthalate esters in agricultural soil with plastic film mulching in Shandong Peninsula

    East China. Chemosphere.

    (2016)
  • C.S. Liao et al.

    Bioremediation of endocrine disruptor di-n-butyl phthalate ester by Deinococcus radiodurans and Pseudomonas stutzeri

    Chemosphere

    (2010)
  • M. Lombo et al.

    Transgenerational inheritance of heart disorders caused by paternal bisphenol A exposure

    Environ Pollut

    (2015)
  • X.C. Qiu et al.

    Tributyltin and perfluorooctane sulfonate play a synergistic role in promoting excess fat accumulation in Japanese medaka (Oryzias latipes) via in ovo exposure

    Chemosphere

    (2019)
  • X.C. Qiu et al.

    Combined toxicities of tributyltin and polychlorinated biphenyls on the development and hatching of Japanese medaka (Oryzias latipes) embryos via in ovo nanoinjection

    Chemosphere

    (2019)
  • A.M. Saillenfait et al.

    Developmental toxic effects of diisobutyl phthalate, the methyl-branched analogue of di-n-butyl phthalate, administered by gavage to rats

    Toxicol Lett

    (2006)
  • S.M. Samaee et al.

    Efficacy of the hatching event in assessing the embryo toxicity of the nano-sized TiO2 particles in zebrafish: A comparison between two different classes of hatching-derived variables

    Ecotox Environ Safe

    (2015)
  • G. Vatine et al.

    It's time to swim! Zebrafish and the circadian clock

    Febs Letters

    (2011)
  • W. Wang et al.

    Long-term bisphenol S exposure induces fat accumulation in liver of adult male zebrafish (Danio rerio) and slows yolk lipid consumption in F1 offspring

    Chemosphere

    (2019)
  • X.Y. Wang et al.

    Gestational and lactational exposure to di-isobutyl phthalate via diet in maternal mice decreases testosterone levels in male offspring

    Chemosphere

    (2017)
  • N. Xu et al.

    Effects of combined exposure to 17α-ethynylestradiol and dibutyl phthalate on the growth and reproduction of adult male zebrafish (Danio rerio)

    Ecotoxicol Environ Saf

    (2014)
  • S. Xu et al.

    Exposure to phthalates impaired neurodevelopment through estrogenic effects and induced DNA damage in neurons

    Aquat Toxicol

    (2020)
  • F. Yadetie et al.

    RNA-Seq analysis of transcriptome responses in Atlantic cod (Gadus morhua) precision-cut liver slices exposed to benzo a pyrene and 17 alpha-ethynylestradiol

    Aquat Toxicol

    (2018)
  • E.E. Yost et al.

    Hazards of diisobutyl phthalate (DIBP) exposure: A systematic review of animal toxicology studies

    Environ Int

    (2019)
  • Cited by (19)

    • The neurotoxicity and mechanism of TBBPA-DHEE exposure in mature zebrafish (Danio rerio)

      2023, Comparative Biochemistry and Physiology Part - C: Toxicology and Pharmacology
    View all citing articles on Scopus
    View full text