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Nanomaterials have attracted much attention in the biomedical field. Black phosphorus quantum dots (BPQDs) have shown great potential in biomedical applications, but their potential risks to biosafety and environmental stability have not been fully evaluated. In the present study, zebrafish (Danio rerio) embryos were exposed to 0, 2.5, 5 and 10 mg/L BPQDs from 2 to 144 h post-fertilization (hpf) to explore developmental toxicity. The results showed that exposure to BPQDs for 96 h induced developmental malformations (tail deformation, yolk sac edema, pericardial edema, and spinal curvature) in zebrafish embryos. ROS and antioxidant enzyme activities (CAT, SOD, MDA and T-AOC) were substantially altered and the acetylcholinesterase (AChE) enzyme activity was significantly decreased in the BPQDs exposed groups. Locomotor behavior was inhibited after BPQDs exposure for 144 h in zebrafish larvae. A significant increase in 8-OHdG content indicates DNA oxidative damage in embryos. In addition, obvious apoptotic fluorescence signals were detected in the brain, spine, yolk sac and heart. At the molecular level, the mRNA transcript levels of key genes related to skeletal development (igf1, gh, MyoD and LOX), neurodevelopment (gfap, pomca, bdnf and Mbpa), cardiovascular development (Myh6, Nkx2.5, Myl7, Tbx2b, Tbx5 and Gata4) and apoptosis (p53, Bax, Bcl-2, apaf1, caspase-3 and caspase-9) were abnormal after BPQDs exposure. In conclusion, BPQDs induced morphological malformations, oxidative stress, locomotor behavior disorders, DNA oxidative damage and apoptosis in zebrafish embryos. This study provides a basis for further study on the toxic effects of BPQDs. [Display omitted] • BPQDs caused developmental toxicity in the zebrafish embryos. • BPQDs induced oxidative stress, oxidative DNA damage and apoptosis in zebrafish embryos. • BPQDs induced developmental neurotoxicity and decreased locomotor behavior. [ABSTRACT FROM AUTHOR]

Dechlorane Plus (DP) is a widely used chlorinated flame retardant, which has been extensively detected in the environment. Although DP content in the surface water is low, it can pose a continuous exposure risk to aquatic organisms due to its strong bioaccumulation. Considering that the related studies on the toxicity mechanism of DP exposure are limited, the effect of DP on carp embryo development was evaluated. In the present work, carp embryos were exposed to different concentrations (0, 30, 60, and 120 μg/L) of DP at 3 h post-fertilization (hpf). The expression levels of neural and skeletal development-associated genes, such as sox2, sox19a, Mef2c and BMP4 , were detected with quantitative PCR, and the changes in different developmental toxicity endpoints were observed. Our results demonstrated that the expression levels of sox2, sox19a, Mef2c and BMP4 were significantly altered and several developmental abnormalities were found in DP-exposed carp embryos, such as DNA damage, increased mortality rate, delayed hatching time, reduced hatching rate, decreased body length, and increased morphological deformities. In addition, the activities of reactive oxygen species and malondialdehyde were remarkably higher in 60 and 120 μg/L DP exposure groups than in control group. These results suggest that DP can exhibit a unique modes of action, which lead to aberration occurrence in the early development stage of common carps, which may be related to some gene damage and oxidative stress. Besides, the parameters evaluated here can be used as tools to access the environmental risk for biota and humans exposed to DP. Image 1 • DP has embryotoxic effects on common carp. • DP could delay embryo development and even cause embryo death. • DP exposure could induce DNA damage and oxidative stress. • ROS and MDA may play an important role in DP-induced developmental deformity. [ABSTRACT FROM AUTHOR]

Ovary development is a complex process involving numerous genes; the molecular mechanism underlying the ovary development of carp is still unknown. Here we used Illumina HiSeq™ 2500 to explore the transcriptome of undifferentiated gland (PG), juvenile ovary (OJ) and adult ovary (OA) of Yellow River carp ( Cyprinus carpio ). A total of 58,749 unigenes were obtained, comprising 45,707 known genes and 13,042 new genes. We identified differentially-expressed genes (DEGs) during development and characterized the functional properties of DEGs by comparison with the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes databases. qRT-PCR was used to analyze the expression of 22 DEGs and the results corresponded with those of RNA-Seq. Among DEGs between PG and OJ, some upstream regulators of gonad development were upregulated in PG, such as cyp19a and sox9 , while some oocyte-specific genes were upregulated in OJ, such as nobox, bmp15 and zp2 . Among DEGs between OJ and OA, many oocyte physiological function-related genes were upregulated in OA, such as fem-1 and foxl2 . GO analysis showed a higher number of DEGs from PG–OJ analysis were assigned to reproduction terms. Furthermore, our investigation has also revealed DEGs identified from PG–OJ analysis were enriched in several important functional pathways, such as Fanconi anemia and the notch signal pathway. These data suggested a dynamic shift in gene expression during ovary development, and DEGs between PG and OJ provided crucial candidate gene data for the study of ovarian differentiation. Additionally, a total of 1,776,769 single nucleotide polymorphisms and 157,279 INDEs were revealed from transcriptome data. This result will contribute to knowledge of ovary differentiation of Yellow River carp. [ABSTRACT FROM AUTHOR]

[Display omitted] • The toxicity effects of mixture and MCPA-Na were compared. • The herbicide mixtures caused a more serious lethal effect and teratogenicity. • The herbicide mixtures produced synergistic effect among embryos. • Explored the potential mechanism of synergistic effect caused by herbicide mixtures. Herbicides may pose considerable danger to non-target aquatic organisms and further threaten human health. The present investigation was aimed to assess the effects of 2-methyl-4-chlorophenoxy acetic acid (MCPA-Na) on Cyprinus carpio embryos. Embryos were exposed to six concentrations of MCPA-Na (0, 52, 54, 56, 58 and 60 mg/L) for 96 h. A series of symptoms were observed in developmental embryos during MCPA-Na exposure, including increased death, hatching inhibited and morphological deformities. Further, MCPA-Na exposure leading to a series of morphological changes (pericardial edema, tail deformation, and spine deformation) in embryos, which were consistent with modifications in the associated genes. In this work, we also investigated the joint toxicity of herbicides (MCPA-Na and cyhalofop-butyl) commonly used in paddy fields on carp embryos, using the 96 h-LC 50 of herbicides (59.784 mg/L MCPA-Na and 1.472 mg/L cyhalofop-butyl) and confirmed that a synergistic effect existing in the binary mixtures. [ABSTRACT FROM AUTHOR]

• We investigated the impacts of progesterone on the crucian carp. • Progesterone can affect the expression of genes in the cricadian rhythm and HPG axes. • The sex ratio shifted toward females following exposure to progesterone. Progesterone (P4) is an extensively applied progestin in human and veterinary medicine that has been widely detected in ambient aquatic environments, which can be detrimental to the health of aquatic organisms. Here we investigate the long-term effects of P4 on the transcription of genes related to the circadian rhythm signaling pathway and hypothalamic-pituitary-gonadal (HPG) axes in the crucian carp, which may have a potentially negative on endocrine-disrupting and sex differentiation impacts. Our results suggest that the expression of genes associated with the circadian rhythm signaling pathway are altered following exposure for 10, 20, 30, 40, 50 and 60 d, leading to disorders in the endocrine system disorders and the regulation of HPG axes-related gene expression. These maladies may affect gonadal development and the reproductive systems of crucian carp and provide a plausible mechanism for the observed change in sex ratio toward females after 180 d. [ABSTRACT FROM AUTHOR]