Ascertaining sensitive exposure biomarkers of various metal(loid)s to embryo implantation

Close relationships exist between metal(loid)s exposure and embryo implantation failure (EIF) from animal and epidemiological studies. However, there are still inconsistent results and lacking of sensitive metal(loid) exposure biomarkers associated with EIF risk. We aimed to ascertain sensitive metal(loid) biomarkers to EIF and provide potential biological explanations. Candidate metal(loid) biomarkers were measured in the female hair (FH), female serum (FS), and follicular fluid (FF) with various exposure time periods. An analytical framework was established by integrating epidemiological association results, comprehensive literature searching, and knowledge-based adverse outcome pathway (AOP) networks. The sensitive biomarkers of metal(loid)s along with potential biological pathways to EIF were identified in this framework. Among the concerned 272 candidates, 45 metal(loid)s biomarkers across six time periods and three biomatrix were initially identified by single-metal(loid) analyses. Two biomarkers with counterfactual results according to literature summary results were excluded, and a total of five biomarkers were further determined from 43 remained candidates in mixture models. Finally, four sensitive metal(loid) biomarkers were eventually assessed by overlapping AOP networks information, including Se and Co in FH, and Fe and Zn in FS. AOP networks also identified key GO pathways and proteins involved in regulation of oxygen species biosynthetic, cell proliferation, and inflammatory response. Partial dependence results revealed Fe in FS and Co in FH at their low levels might be potential sensitive exposure levels for EIF. Our study provided a typical framework to screen the crucial metal(loid) biomarkers and ascertain that Se and Co in FH, and Fe and Zn in FS played an important role in embryo implantation.

Determination of Time Progression and Sensitive Biomarkers of Maternal Zinc Depletion in Broiler Chickens and Pekin Ducks Fed a Zinc-Deficient Diet

Two experiments were performed to assess maternal zinc (Zn) depletion in broiler chickens and Pekin ducks fed a Zn-deficient diet. The time of Zn depletion was assessed based on growth performance, and sensitive biomarkers were determined based on tissue Zn content via a linear regression model. A total of 200 1-day-old male broiler chickens (experiment 1) and 200 1-day-old male Pekin ducks (experiment 2) were randomly allocated to 2 diets with 10 replicate cages (10 birds/cage). The two diets were a zinc-deficient diet (ZnD, 20.42 mg Zn/kg) and a control zinc diet (CON, 84.77 mg Zn/kg). In experiment 1, compared to CON, ZnD decreased (P < 0.05) the body weight (days 7, 14, and 21), body weight gain, feed intake (days 1-7, 1-14, and 1-21), and the Zn content of plasma (days 7 and 21), pancreas (days 7, 14, and 21), and tibia in broiler chickens. The R² of a linear model was greater at day 7 than at day 14 or day 21 for pancreatic Zn content in broiler chickens. In experiment 2, compared to CON, ZnD also decreased (P < 0.05) the body weight (days 7, 14, and 21), body weight gain (days 1-7, 1-14, and 1-21), and feed intake (days 1-14 and 1-21) and increased (P < 0.05) the feed-to-gain ratio (days 1-7 and 1-14) in ducks. Compared with CON, ZnD reduced (P < 0.05) the Zn content of the pancreas (days 7, 14, and 21), tibia (days 7, 14, and 21), and skin (days 14 and 21) and increased (P < 0.05) the Zn content of the plasma (day 21) and skin (day 7) in ducks. The R² of a linear model was greater at day 7 than at days 14 or 21 for skin Zn content in ducks. The results indicated that the maternal Zn was depleted by 7 days of age in both birds; the sensitive biomarker for broiler chickens is pancreatic Zn content, and for ducks, it is skin Zn content.

Short-term personal PM2.5 exposure and change in DNA methylation of imprinted genes: Panel study of healthy young adults in Guangzhou city, China

DNA methylation (DNAm) plays a significant role in deleterious health effects inflicted by fine particulate matter (PM_2.5) on the human body. Recent studies have reported that DNAm of imprinted control regions (ICRs) in imprinted genes may be a sensitive biomarker of environmental exposure. Less is known about specific biomarkers of imprinted genes after PM_2.5 exposure. The relationship between PM_2.5 and its chemical constituents and DNAm of ICRs in imprinted genes after short-term exposure was investigated to determine specific human biomarkers of its adverse health effects. A panel study was carried out in healthy young people in Guangzhou, China. Mixed-effects models were used to evaluate the influence of PM_2.5 and its constituent exposure on DNAm while controlling for potential confounders. There was no significant correlation between DNAm and personal PM_2.5 exposure mass. DNAm changes in eight ICRs (L3MBTL1, NNAT, PEG10, GNAS Ex1A, MCTS2, SNURF/SNRPN, IGF2R, and RB1) and a non-imprinted gene (CYP1B1) were significantly associated with PM_2.5 constituents. Compared to non-imprinted genes, imprinted gene methylation was more susceptible to interference with PM_2.5 constituent exposure. Among those genes, L3MBTL1 was the most sensitive to personal PM_2.5 constituent exposure. Moreover, transition metals derived from traffic sources (Cd, Fe, Mn, and Ni) significantly influenced DNAm of the imprinted genes, suggesting the importance of more targeted measures to reduce toxic constituents. Bioinformatics analysis indicated that imprinted genes (RB1) may be correlated with pathways and diseases (non-small cell lung cancer, glioma, and bladder cancer). The present study suggests that screening the imprinted gene for DNAm can be used as a sensitive biomarker of PM_2.5 exposure. The results will provide data for prevention of PM_2.5 exposure and a novel perspective on potential mechanisms on an epigenetic level.