Functional disruption in epidermal barrier enhances toxicity and accumulation of graphene oxide

Cadmium-induced reproductive toxicity combined with a correlation to the oogenesis process and competing endogenous RNA networks based on a Caenorhabditis elegans model

Accumulation of the heavy metal Cadmium (Cd) in the ovaries and placenta can affect the structure and function of these organs and induce female reproductive toxicity. This toxicity may be due to Cd's similarity to estrogen and its ability to disrupt endocrine systems. However, the exact molecular mechanism by which Cd causes reproductive toxicity at the transcriptome level remains poorly understood. Hence, this study aimed to observe Cd-induced reproductive damage at the gene level, scrutinize the repercussions of Cd exposure on oogenesis, and explicate the putative pathogenesis of Cd-induced oogenesis based on Caenorhabditis elegans (C. elegans) as an in vivo model. The results showed that Cd exposure significantly decreased the number of offspring and prolonged the reproductive span of C. elegans. Cd exposure also reduced the number of cells in mitosis and the pachytene and diakinesis stages of meiosis, thereby disrupting oogenesis. Combined with transcriptional sequencing and bioinformatics analysis, a total of 3167 DEmRNAs were identified. Regarding gene expression, cul-6, mum-2, and vang-1 were found to be related to Cd-induced reproductive toxicity, and their competing endogenous RNA networks were constructed. We observed that mutations of mom-2 and vang-1 in the Wnt pathway could induce susceptibility to Cd-caused meiosis injury. In conclusion, the results indicated that Cd could impair the oogenesis of C. elegans and the Wnt pathway might serve as a protective mechanism against Cd reproductive toxicity. These findings contribute to a better understanding of the damaging effects and molecular biological mechanisms of Cd on the human reproductive system.

CdTe-QDs Affect Reproductive Development of Plants through Oxidative Stress

With the continuous development of industry, an increasing number of nanomaterials are widely used. CdTe-QDs is a nanomaterial with good optical properties, but its release into the natural environment may pose a potential threat. The toxicity of nanoparticles in plants is beginning to be questioned, and the effect on phytotoxicity is unclear. In this study, we simulated air pollution and soil pollution (CdTe-QDs concentrations of 0, 0.2, 0.4, 0.8 mmol/L) by spraying and watering the seedlings, respectively. We determined the transport pathways of CdTe-QDs in Arabidopsis thaliana and their effects on plant reproductive growth. Spraying CdTe-QDs concentration >0.4 mmol/L significantly inhibited the formation of fruit and decreased the number of seeds. Observation with a laser confocal scanning microscope revealed that CdTe-QDs were mainly transported in plants through the vascular bundle, and spraying increased their accumulation in the anthers and ovaries. The expression level of genes associated with Cd stress was analyzed through RT-qPCR. CdTe-QDs significantly increased the expression levels of 10 oxidative stress-related genes and significantly decreased the expression levels of four cell-proliferation-related genes. Our results reveal for the first time the transport of CdTe-QDs in Arabidopsis flowers and demonstrate that QDs can cause abnormal pollen morphology, form defects of pollen vitality, and inhibit pollen tube growth in Arabidopsis through oxidative damage. These phenomena ultimately lead to the inability of Arabidopsis to complete the normal fertilization process and affect the reproductive growth of the plant.

The Caenorhabditis elegans cuticle plays an important role against toxicity to bisphenol A and bisphenol S

Caenorhabditis elegans represents a favorite non-mammalian animal model, which is often used to study the effect of foreign substances on living organisms. Its epidermal barrier is a primary biological barrier that protects nematodes from the toxicity of chemicals. In this study, we investigated the effect of Bisphenol A (BPA), an endocrine disrupting chemical, and its structural analog Bisphenol S (BPS), which is often used as a substitute for BPA in some products, on the behavior of C. elegans wild type (N2) and C. elegans bli-1 mutant strain, which is characterized by the production of abnormal cuticle blisters. We found that exposure of C. elegans wild type (N2), as well as its mutant strain bli-1, to selected concentrations of BPA (0.1, 0.5, 1 and 5 µM) and BPS (0.1, 0.5, 1 and 5 µM) resulted in significant changes in reproduction, habituation behavior, and body length of nematodes. Based on our findings, we can conclude that BPS, which was supposed to be a safer alternative to BPA, caused almost identical detrimental effects on C. elegans behavior. Furthermore, compared to the wild type of C. elegans, these effects were more pronounced in the bli-1 strain, which is characterized by a mutation in an individual collagen gene responsible for proper cuticle formation, underlying the role of the epidermal barrier in bisphenol toxicity. Taken together, our data indicate the potential risks of using BPS as a BPA alternative.

Sublethal toxicity of graphene oxide in Caenorhabditis elegans under multi-generational exposure

Nanomaterials have received increasing attentions owing to their potential hazards to the environment and human health; however, the multi-generational toxicity of graphene oxide under consecutive multi-generational exposure scenario still remains unclear. In the present study, Caenorhabditis elegans as an in vivo model organism was employed to explore the multi-generational toxicity effects of graphene oxide and the underlying mechanisms. Endpoints including development and lifespan, locomotion behaviors, defecation cycle, brood sizes, and oxidative response were evaluated in the parental generation and subsequent five filial generations. After continuous exposure for several generations, worms grew smaller and lived shorter. The locomotion behaviors were reduced across the filial generations and these reduced trends were following the impairments of locomotion-related neurons. In addition, the extended defecation cycles from the third filial generation were in consistency with the relative size reduction of the defecation related neuron. Simultaneously, the fertility function of the nematode was impaired under consecutive exposure as reduced brood sizes and oocytes numbers, increased apoptosis of germline, and aberrant expression of reproductive related genes ced-3, ced-4, ced-9, egl-1 and ced-13 were detected in exposed worms. Furthermore, the antioxidant enzyme, SOD-3 was significantly increased in the parent and filial generations. Thus, continuous multi-generational exposure to graphene oxide caused damage to the neuron development and the reproductive system in nematodes. These toxic effects could be reflected by indicators such as growth inhibition, shortened lifespan, and locomotion behavior impairment and induced oxidative response.

Vitellogenin expression, DNA damage, health status of cells and catalase activity in Acheta domesticus selected according to their longevity after graphene oxide treatment

The increased use of graphene oxide (GO) raises worrisome questions regarding its possible threat to various ecosystems. Invertebrates represent valuable organisms for environmental studies. The lifespan can influence the ability to cope with toxins, especially those that act via oxidative stress. Two strains of Acheta domesticus, which are selected for longevity, were tested. The main aim was to investigate how GO, when administrated in food, affects: the condition of cells, DNA stability, ROS generation and the reproduction potential (the Vitellogenin (Vg) protein expression). The "recovery effect" - after removing GO from the diet for 15 days - was also measured. The results revealed different responses to GO in the wild (H) and long-living (D) strains. The D strain had a higher catalase activity compared to the H strain on the 25th day of the imago stage. Removing GO from the food resulted in a decrease in the catalase activity to the level of the control. On the 5th day of the imago stage, the H strain had a higher cell mortality than the D strain in the GO-intoxicated groups. There was more DNA damage in the H strain compared to the long-living strain. A remedial effect was seen after the GO was removed from the diet. The total Vg protein expression was higher in the H strain and lower in the D strain. The results indicated a GO concentration-dependent outcome. In both strains, removing the GO from the food led to a high Vg expression. The Vg expression after GO treatment, particularly translation and post-translational processing, should be studied in detail in the future. The D strain of crickets had more specialized mechanisms for maintaining homeostasis than the H strain. Organisms can fight off negative effects of GO, especially when they have systems that are well developed against oxidative stress.

Exposure to MPA-capped CdTe quantum dots causes reproductive toxicity effects by affecting oogenesis in nematode Caenorhabditis elegans

Quantum dots (QDs), considered as a type of excellent semiconductor nanomaterial, are widely employed and have a number of important applications. However, QDs have the potential to produce adverse effects and toxicity with the underlying molecular mechanisms not well understood. Herein, Caenorhabditis elegans was used for in vivo toxicity assessment to detect the reproductive toxicity of CdTe QDs. We found that exposure to CdTe QDs particles (≥ 50 mg/L) resulted in a defect in reproductive capacity, dysfunctional proliferation and differentiation, as well as an imbalance in oogenesis by reducing the number of cells in pachytene and diakinesis. Further, we identified a SPO-11 and PCH-2 mediated toxic mechanism and a GLP-1/Notch mediated protective mechanism in response to CdTe QDs particles (≥ 50 mg/L). Taken together, these results demonstrate the potential adverse impact of CdTe QDs (≥ 50 mg/L) exposure on oogenesis and provide valuable data and guidelines for evaluation of QD biocompatibility.