Ecotoxicological effects of commercial herbicides on the reproductive system of aquatic arthropod Limnocoris submontandoni (Hemiptera: Naucoridae)

Worldwide, conventional agriculture makes extensive use of pesticides. Although the effects of herbicides are relatively well known in terms of environmental impacts on non-target organisms, there is very little scientific evidence regarding the impacts of herbicide residues on aquatic arthropods from tropical conservation areas. This study evaluates for the first time the toxicity of the herbicides ametryn, atrazine, and clomazone on the aquatic insect Limnocoris submontandoni (Hemiptera: Naucoridae). The lethal concentration (LC50) of herbicides was evaluated for these insects, as well as the effect of the herbicides on the insects’ tissues and testicles. The estimated LC50 was 1012.41, 192.42, and 46.09 mg/L for clomazone, atrazine, and ametryn, respectively. Spermatocyte and spermatid changes were observed under the effect of atrazine, and effects on spermatogenesis were observed for some concentrations of clomazone, with apparent recovery after a short time. Our results provide useful information on the effects of herbicide residues in aquatic systems. This information can help minimize the risk of long-term reproductive effects in non-target species that have been previously overlooked in ecotoxicology studies.

Born without night: The consequence of the no-night environment on reproductive performance in diurnal zebra finches

We investigated the consequence of no night environment (constant light, LL) on reproductive performance in zebra finches in the parent (P) and subsequent F1 generation. As a measure of the overall effects on the metabolic reproductive health, we monitored daily activity behaviour, recorded song and cheek patch size in males, and measured body size and hormone levels. As compared to controls under 12 h light: 12 h darkness (12:12 h LD), both P and F1 pairs showed a compromised reproductive success, as evidenced by fewer fledglings and viable offsprings with longer fledging durations, and increased offspring mortality with successive three clutches under LL. The overall negative effect of the no-night environment was increased in the F1generation. As compared to P pairs, F1pairs had more failed nesting and breeding attempts, took longer to initiate reproduction, incubated fewer eggs, produced fewer viable offspring with longer fledging duration, and showed increased offspring mortality. Consistent with negative reproductive effects, P males showed significant changes in the motif duration and other spectral features of song, and both F1 and F2 males copied poorly the song of their parent under LL. Plasma corticosterone and sex hormones (testosterone in males and estradiol in females) levels were significantly lower under LL. Daily plasma melatonin rhythm persisted but with a reduced amplitude under LL. These results demonstrate the importance of night in reproduction in a continuously breeding diurnal species, and give insights into the possible impact on physiology of animals whose surrounding environment is consistently losing the darkness of night.

A Review of Per- and Polyfluorinated Alkyl Substance Impairment of Reproduction

In this review article, we compiled peer-reviewed literature describing PFAS exposure and reproductive effects in animals and humans. The aim was to compare environmental occurrence and effects of the most prominent long-chain PFAS compounds and their short-chain replacements. Long-chain PFAS compounds are known to persist in the environment due to their chemical stability, and also known to bioaccumulate; hence, these compounds are being replaced globally. Indeed, PFOA and PFOS are considered long-chain “forever pollutants,” and thus the potential reproductive risk may continue for decades. Much less is known about their short-chain replacements despite the fact that they becoming more widespread in the environment. Short-chain PFAS are generally less bioaccumulative than long-chain, but they are more mobile and persistent in aquatic ecosystems. The three most prominent of these are commonly referred to as GenX, ADONA and F53B. The short-chain PFAS have similar physical and chemical properties as their predecessors; however, because they are relatively new, much less is known about the potential to disrupt reproduction. Indeed, high-quality epidemiological studies are needed to determine associations between short-chain PFAS exposure and effects on reproductive health. However, epidemiological evidence is mounting that long-chain PFAS exposure is associated with reproductive effects (i.e., decrease in fertility, reduced fetal growth and birth weight, pregnancy-induced hypertension and preeclampsia, thyroid hormone disruption during pregnancy, and preterm birth). Evidence from animal models and human cell lines indicates that short-chain PFAS similarly affect reproductive endpoints; however, epidemiological studies are scarce and inconsistent. Although short-chain PFAS have been quantified in drinking water and sediment worldwide, most of these studies did not focus on quantitation of GenX, ADONA, and F53B. There are also many other short-chain PFAS byproducts of manufacturing that have yet to be identified and studied. When sum total concentration of long- and short-chain PFAS are considered, the concentration rises by an order or magnitude or greater, as will the risk of exposure and subsequent reproductive effects.

Animal Toxicology Studies on the Male Reproductive Effects of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin: Data Analysis and Health Effects Evaluation

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known environmental poison that exist in the environment for many years. However, its effect on the male reproductive system has not been clearly stated. We conducted a meta-analysis of the effect of TCDD on the male reproductive system of rodents about TCDD. Results showed that that TCDD exposure reduced the testis weight (weighted mean difference [WMD]: −0.035, 95% confidence interval [CI]: −0.046 to −0.025), sperm count (WMD: −35, 95% CI: −42.980 to −27.019), and blood testosterone concentration (WMD: −0.171, 95% CI: −0.269 to −0.073). According to our research results, TCDD can cause damage to the male reproductive system of rodents through direct or indirect exposure. In order to further explore the potential hazards of TCDD to humans, more human-related research needs to be carried out.

Reproductive Deficits Induced by Prenatal Anti-Mullerian Hormone Exposure Require Androgen Receptor in Kisspeptin Cells

Polycystic ovary syndrome (PCOS) is a common reproductive disorder characterized by elevated androgens and anti-Mullerian hormone (AMH). These hormones remain elevated throughout pregnancy, and potential effects of hormone exposure on offspring from women with PCOS remain largely unexplored. Expanding on recent reports of prenatal AMH exposure in mice, we have fully characterized the reproductive consequences of prenatal AMH (pAMH) exposure throughout the lifespan of first- and second-generation offspring of both sexes. We also sought to elucidate mechanisms underlying pAMH-induced reproductive effects. There is a known reciprocal relationship between AMH and androgens, and in PCOS and PCOS-like animal models, androgen feedback is dysregulated at the level the hypothalamus. Kisspeptin neurons express androgen receptors and play a critical role in sexual development and function. We therefore hypothesized that pAMH-induced reproductive phenotypes would be mediated by androgen signaling at the level of kisspeptin cells. We tested the pAMH model in kisspeptin-specific androgen receptor knockout (KARKO) mice and found that virtually all pAMH-induced phenotypes assayed are eliminated in KARKO offspring compared to littermate controls. By demonstrating the necessity of androgen receptor in kisspeptin cells to induce pAMH phenotypes, we have advanced understanding of the interactions between AMH and androgens in the context of prenatal exposure, which could have significant implications for children of women with PCOS.

Effects of deoxynivalenol exposure at peripuberty over testicles of rats: structural and functional alterations

Deoxynivalenol (DON) is related to reduced reproductive performance in males and females in several species. Children and adolescents showed a high risk of exposure to DON, however, no study has evaluated reproductive effects of DON at puberty. The present study aimed to evaluate the effects of DON at peripuberty on the testicles of pubertal rats. To achieve this, 10 Wistar rats (28 days old) were fed for 28 days with a DON-contaminated diet (9.4 mg/kg) or a control diet. After the experimental period, rats (56 days old) were euthanised and the following evaluations were performed in the testicles: dynamics of spermatogenesis, tubular morphometry, number of Sertoli cells and Leydig cells, analysis of caspase-3 expression, and the index of cell proliferation using the nucleolus organising regions (NOR) method. Ingestion of DON-contaminated diet induced a significant reduction in the number of Sertoli and Leydig cells and the number of seminiferous tubules in stage XIV. A significant increase in the number of NORs in seminiferous tubules in stage I-VI was observed in animals receiving the DON diet. No significant difference was noted in tubular morphometry or caspase-3 expression. Taken together, our results unravelled that the peripubertal exposure to DON compromised the testicular structure of pubertal rats, changing the dynamics of spermatogenesis.

Maternal occupation as a nail technician or hairdresser during pregnancy and birth defects, National Birth Defects Prevention Study, 1997–2011

ObjectiveNail technicians and hairdressers may be exposed to chemicals with potential reproductive effects. While studies have examined birth defects in children of hairdressers, those in children of nail technicians have not been evaluated. We investigated associations between selected birth defects and maternal occupation as a nail technician or hairdresser versus a non-cosmetology occupation during pregnancy.MethodsWe analysed population-based case–control data from the multisite National Birth Defects Prevention Study, 1997–2011. Cases were fetuses or infants with major structural birth defects; controls were live-born infants without major birth defects. Expert raters classified self-reported maternal jobs as nail technician, combination nail technician-hairdresser, hairdresser, other cosmetology work or non-cosmetology work. We used logistic regression to calculate adjusted ORs and 95% CIs for associations between occupation during pregnancy and birth defects, controlling for age, smoking, education and race/ethnicity.ResultsSixty-one mothers worked as nail technicians, 196 as hairdressers, 39 as combination nail technician-hairdressers and 42 810 as non-cosmetologists. The strongest associations among nail technicians included seven congenital heart defect (CHD) groups (ORs ranging from 2.7 to 3.5) and neural tube defects (OR=2.6, CI=0.8 to 8.4). Birth defects most strongly associated with hairdressing included anotia/microtia (OR=2.1, CI=0.6 to 6.9) and cleft lip with cleft palate (OR=2.0, CI=1.1 to 3.7). All oral cleft groups were associated with combination nail technician-hairdresser work (ORs ranging from 4.2 to 5.3).ConclusionsSmall samples resulted in wide CIs. Still, results suggest associations between maternal nail technician work during pregnancy and CHDs and between hairdressing work and oral clefts.