Oocyte Development and Quality in Young and Old Mice following Exposure to Atrazine

Screening and characterization of 133 physiologically-relevant environmental chemicals for reproductive toxicity

Reproduction is a functional outcome that relies on complex cellular, tissue, and organ interactions that span the developmental period to adulthood. Thus, the assessment of its disruption by environmental chemicals would benefit significantly from scalable and innovative approaches to testing using functionally comparable reproductive models such as the nematode C. elegans. We adapted a previously described low-throughput in vivo chromosome segregation assay using C. elegans predictive of reproductive toxicity and leveraged available public data sources (ToxCast, ICE) to screen and characterize 133 physiologically-relevant chemicals in a high-throughput manner. The screening outcome was further validated in a second, independent in vivo assay assessing embryonic viability. In total, 13 chemicals were classified as reproductive toxicants with the two most active chemicals belonging to the large family of Quaternary Ammonium Compounds (QACs) commonly used as disinfectants but with limited available reproductive toxicity data. We compared the results from the C. elegans assay with ToxCast in vitro data compiled from 700+ cell response assays and 300+ signaling pathways-based assays. We did not observe a difference in the bioactivity or in the average potency (AC50) between the top and bottom chemicals. However, the intended target categories were significantly different between the classified chemicals with, in particular, an over-representation of steroid hormone targets for the high Z-score chemicals. Taken together, these results point to the value of in vivo models that scale to high-throughput level for reproductive toxicity assessment and to the need to prioritize the assessment of QACs impacts on reproduction.

Screening and characterization of 133 physiologically-relevant environmental chemicals for reproductive toxicity

Reproduction is a functional outcome that relies on complex cellular, tissue, and organ interactions that span the developmental period to adulthood. Thus, the assessment of its disruption by environmental chemicals is remarkably painstaking in conventional toxicological animal models and does not scale up to the number of chemicals present in our environment and requiring testing. We adapted a previously described low-throughput in vivo chromosome segregation assay using C. elegans predictive of reproductive toxicity and leveraged available public data sources (ToxCast, ICE) to screen and characterize 133 physiologically-relevant chemicals in a high-throughput manner. The screening outcome was further validated in a second, independent in vivo assay assessing embryonic viability. In total, 13 chemicals were classified as reproductive toxicants with the two most active chemicals belonging to the large family of Quaternary Ammonium Compounds (QACs) commonly used as disinfectants but with limited available reproductive toxicity data. We compared the results from the C. elegans assay with ToxCast in vitro data compiled from 700+ cell response assays and 300+ signaling pathways-based assays. We did not observe a difference in the bioactivity or in average potency (AC50) between the top and bottom chemicals. However, the intended target categories were significantly different between the classified chemicals with, in particular, an over-representation of steroid hormone targets for the high Z-score chemicals. Taken together, these results point to the value of in vivo models that scale to high-throughput level for reproductive toxicity assessment and to the need to prioritize the assessment of QACs impacts on reproduction.

Spatial distribution and ecological-health risks associated with herbicides in soils and crop kernels of the black soil region in China

Herbicides are vital inputs for food production; however, their associated risks and hazards are pressing concerns. In black soil, the cumulative toxic effects of compound herbicides and potential risks to humans are not yet fully understood. Thus, this study conducted a comprehensive investigation to assess herbicide residue characteristics and the associated ecological health risks in representative black soil regions where major food crops (maize, soybean, and rice) are cultivated. Findings revealed that the soil harbored a collective presence of 29 herbicides, exhibiting total concentrations ranging from 111.92 to 996.14 μg/kg dry weight (dw). This can be attributed to the extensive use of herbicides over the years and their long half-lives, which results in the accumulation of multiple herbicide residues in the soil. Similarly, the total herbicide levels in maize, soybean, and rice kernels were 1173-61,564, 1721-9342, and 3775-8094 ng/kg dw, respectively. Multiple herbicide residues at all monitored sites were attributed to continuous crop barriers in soybean fields and the adoption of soybean and maize crop rotations. Notably, herbicides pose ecological risks in the black soil region, exhibiting high-risk levels of 79 %, 24 %, and 14 % at the sites monitored for oxyfluorfen, clomazone, and butachlor, respectively. Carcinogenic atrazine exhibited low- and medium-risk levels in 34 % and 63 % of soil samples, respectively. These results can serve as a scientific basis for establishing herbicide residue thresholds in agricultural soils within black soil areas and for implementing effective control measures to prevent herbicide contamination in agricultural ecosystems.

Effect of atrazine on testicular toxicity involves accommodative disorder of xenobiotic metabolizing enzymes system and testosterone synthesis in European quail (Coturnix coturnix)

Due to the wide use of atrazine (ATR), the concern has increased regarding the negative impact of ATR on reproduction. Nevertheless, the reproductive effects caused by different exposure concentrations and the severity of toxic damage are poorly understood. In organisms, ATR is metabolized and degraded through phase II enzyme systems, and changes in cytochrome P450 (CYP) enzymes may have a regulatory role in the harm of ATR. However, less information is available on the induction of CYPs by ATR in avian organisms, and even less on its effects on the testis. Birds are exposed to ATR mainly through food residues and contaminated water, the purpose of this study was to examine reproductive toxicity by different exposure concentrations and elaborate metabolic disorders caused by ATR in European quail (Coturnix coturnix). In this study, the quail were given ATR at 50 mg/kg, 250 mg/kg and 500 mg/kg by oral gavage for 45 days, and the testicular weight coefficients, histopathology and ultrastructure of testes, primary biochemical functions, sex steroid hormones, critical protein levels in the testosterone synthesis pathway, the expression of genes involved CYPs, gonad axis and nuclear receptors expression were investigated. Altogether, testicular coefficient decreased significantly in the high-dose group (1.22%) compared with the control group (3.03%) after 45 days of ATR exposure, and ATR is a potent CYP disruptor that acts through the NXRs and steroid receptor subfamily (APND, CAR, ERND and ERα) without a dose-dependent manner. Notably, ATR interfered with the homeostasis of hormones by triggering the expression of hormones on the gonad axis (LH and E2). These results suggest that exposure to ATR can cause testicular toxicity involving accommodative disorder of phase II enzyme and testosterone synthesis in European quail.

Clinical Significance of Application of Chromosomal Karyotyping of Villus Tissues

Purpose

Karyotype analysis of villus chromosomes in spontaneous abortion by high-throughput ligation-dependent probe amplification (HLPA) was performed to explore relationship between spontaneous abortion and chromosomal abnormalities in spontaneous abortion tissues.

Patients and Methods

The karyotypes of chromosomes of villus tissues from 516 patients with spontaneous abortion who were admitted to our hospital between 2014 and 2019 were analyzed. The data were grouped by the age (ie, ≤29, 30-35, and ≥36 years old) in which embryonic chromosomal abnormality rate, and abnormal distribution of chromosome number in abortion tissue of 294 patients.

Results

The examination of 516 samples of spontaneous abortion tissues showed that the chromosomes of 294 samples were abnormal, and the abnormality rate was 60.97%. Among 294 samples with chromosomal abnormalities, 136 (89.47%) samples had numerical chromosomal abnormalities, 15 (9.87%) samples had structural chromosomal abnormalities, and 1 (0.07%) sample had uniparental disomy. A total of 308 couples voluntarily underwent peripheral blood chromosome analysis. The results showed that 56 couples had abnormality in one or both spouses, and rate of embryonic chromosomal abnormality in these 26 cases with chromosomal abnormalities was 100%.

Conclusion

Numerical and structural chromosomal abnormalities are among the important causes of embryonic arrest, while the increase in age could also be a high-risk factor for embryonic chromosomal abnormality. Therefore, examination of the karyotypes of embryo chorionic villus may help understand the reasons of embryonic arrest, which could provide important guidance for more genetic counseling for patients with early spontaneous abortion, as well as improving the preconception preparation.

Atrazine Toxicity: The Possible Role of Natural Products for Effective Treatment

There are various herbicides which were used in the agriculture industry. Atrazine (ATZ) is a chlorinated triazine herbicide that consists of a ring structure, known as the triazine ring, along with a chlorine atom and five nitrogen atoms. ATZ is a water-soluble herbicide, which makes it capable of easily infiltrating into majority of the aquatic ecosystems. There are reports of toxic effects of ATZ on different systems of the body but, unfortunately, majority of these scientific reports were documented in animals. The herbicide was reported to enter the body through various routes. The toxicity of the herbicide can cause deleterious effects on the respiratory, reproductive, endocrine, central nervous system, gastrointestinal, and urinary systems of the human body. Alarmingly, few studies in industrial workers showed ATZ exposure leading to cancer. We embarked on the present review to discuss the mechanism of action of ATZ toxicity for which there is no specific antidote or drug. Evidence-based published literature on the effective use of natural products such as lycopene, curcumin, Panax ginseng, Spirulina platensis, Fucoidans, vitamin C, soyabeans, quercetin, L-carnitine, Telfairia occidentalis, vitamin E, Garcinia kola, melatonin, selenium, Isatis indigotica, polyphenols, Acacia nilotica, and Zingiber officinale were discussed in detail. In the absence of any particular allopathic drug, the present review may open the doors for future drug design involving the natural products and their active compounds.

Reproductive toxicity of combined effects of endocrine disruptors on human reproduction

Confluence of environmental, genetic, and lifestyle variables is responsible for deterioration of human fecundity. Endocrine disruptors or endocrine disrupting chemicals (EDCs) may be found in a variety of foods, water, air, beverages, and tobacco smoke. It has been demonstrated in experimental investigations that a wide range of endocrine disrupting chemicals have negative effects on human reproductive function. However, evidence on the reproductive consequences of human exposure to endocrine disrupting chemicals is sparse and/or conflicting in the scientific literature. The combined toxicological assessment is a practical method for assessing the hazards of cocktails of chemicals, co-existing in the environment. The current review provides a comprehensive overview of studies emphasizing the combined toxicity of endocrine disrupting chemicals on human reproduction. Endocrine disrupting chemicals interact with each other to disrupt the different endocrine axes, resulting in severe gonadal dysfunctions. Transgenerational epigenetic effects have also been induced in germ cells, mostly through DNA methylation and epimutations. Similarly, after acute or chronic exposure to endocrine disrupting chemicals combinations, increased oxidative stress (OS), elevated antioxidant enzymatic activity, disrupted reproductive cycle, and reduced steroidogenesis are often reported consequences. The article also discusses the concentration addition (CA) and independent action (IA) prediction models, which reveal the importance of various synergistic actions of endocrine disrupting chemicals mixtures. More crucially, this evidence-based study addresses the research limitations and information gaps, as well as particularly presents the future research views on combined endocrine disrupting chemicals toxicity on human reproduction.