Decontamination promotes the release of incorporated organic contaminants in hair: Novel insights into non-invasive biomonitoring.

Human hair is increasingly employed as a non-invasive biomonitoring matrix for exposure to organic contaminants (OCs). Decontamination procedures are generally needed to remove external contamination from hair prior to analysis of OCs. Despite various existing decontamination protocols, their impacts on internally incorporated (endogenous) OCs in hair remain poorly understood. This study aims to quantitatively assess the impact of decontamination procedures on endogenous OCs in hair, and investigate optimal decontamination processes and factors influencing the removal of endogenous OCs. In this study, guinea pig was exposed to 6 OCs (triphenyl phosphate (TPHP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and tri-n-butyl phosphate (TNBP), bisphenol A (BPA), perfluorooctanoic acid (PFOA), and phenanthrene (PHE)), and 6 decontamination procedures with different solvents (methanol, n-hexane, acetone, ultrapure water, Triton X-100, and sodium dodecyl sulfate) were used to rinse exposed guinea pig hair. All OCs and three metabolites (diphenyl phosphate (DPHP), dibutyl phosphate (DBP), and bis(1,3-dichloro-2-propyl) phosphate (BDCPP)) were detected in the majority of washing solutions. The decontamination procedures apparently resulted in the release of endogenous OCs from hair. The percentages of residual OCs in hair exhibited a linear or exponential decrease with more washing cycles. Furthermore, the residuals of OCs in hair washed with organic and aqueous solvents showed negative correlations with molecular weight, polarizability, and their initial concentrations. Although these findings need to be validated with a broader range of OCs, the results obtained in this study provide compelling evidence that current hair decontamination procedures have significant impacts on the analysis of endogenous OCs in hair. Therefore, it is important to interpret quantitative data on hair OC concentrations with caution and to thoroughly consider each decontamination procedure during analysis.

Tracing semi-quantitatively the absorption and removal of organic pollutants in human hair based on secondary ion mass spectrometry.

Human hair has become a promising non-invasive matrix in assessing exposure to environmental organic pollutants (OPs). However, exogenous contaminants, which were absorbed into the hair via sweat, sebum, and air particles/dust, could contribute to OP levels in hair and interfere with the precise exposure assessment. So far, the microscopic mechanisms underlying the absorption of exogenous OPs into hair remain inadequately understood. This study focused on the in-situ investigation of the diffusion processes of exogenous OPs into the hair structure using secondary ion mass spectrometry (SIMS) and isotopic tracer techniques. Results showed that the relative signal intensities of deuterium-labeled tris(1,3-dichloro-2-propyl) phosphate (TDCPP), 1-hydroxypyrene (1-OH-Pry), and bisphenol A (BPA) in the hair cortex were notably elevated after a 6-hour exposure. Diffusion coefficients of contaminants were related to their molecular weight, and absorption volumes to their water solubility and molecular structures. Exposure duration and solvent influenced the rate of diffusion and absorption volumes. The distribution of deuterium-labeled molecules in exposed hair samples after washing with two different solvents (acetone or water) was similar to that before washing. Our findings revealed the diffusion of OPs in hair cross-sections, indicating exogenous contributions to contaminants that are biologically incorporated into the hair.

Pseudopregnant mice generated from Piwil1 deficiency sterile mice.

Vasectomized mice play a key role in the production of transgenic mice. However, vasectomy can cause great physical and psychological suffering to mice. Therefore, there is an urgent need to find a suitable replacement for vasectomized mice in the production of transgenic mice. In this study, we generated C57BL/6J mice (Piwil1 D633A-INS99, Piwil1mt/mt) with a 99-base insertion in the Miwi (Piwil1) gene using CRISPR/Cas9 technology and showed that Piwil1mt/+ heterozygous mice were normally fertile and that homozygous Piwil1mt/mt males were sterile and females were fertile. Transplantation of normal fertilized eggs into wild pseudopregnant females following mating with Piwil1mt/mt males produced no Piwil1mt/mt genotype offspring, and the number of offspring did not differ significantly from that of pseudopregnant mice following mating and breeding with ligated males. The CRISPR‒Cas9 system is available for generating Miwi-modified mice, and provides a powerful resource to replace ligated males in assisted reproduction research.

Melanin-mediated accumulation of polycyclic aromatic hydrocarbons in human hair: Insights from biomonitoring and cell exposure studies.

While human hair is widely used to monitor micro-organic contaminants (MOCs), their incorporation mechanisms are poorly understood. Melanin, known to facilitate the accumulation of drugs in hair, hasn't been studied in the field of MOCs. Here, polycyclic aromatic hydrocarbons (PAHs), a class of priority MOCs, were investigated through hair biomonitoring as well as cell exposure experiments. PAH concentrations and melanin contents were measured in black and white hairs from the same individual. The results showed that five dominant PAHs (phenanthrene, fluoranthene, pyrene, benzo[a]anthracene and chrysene) in black hair (0.66 ng/g - 35.1 ng/g) were significantly higher than those in white hair (0.52 ng/g - 29.6 ng/g). Melanin contents in black hair (14.9 - 48.9 ng/g) were markedly higher than in white hair (0.35 - 2.15 ng/g) and were correlated to PAH concentrations, hinting melanin-mediated accumulation of PAHs in hair. The in vitro experiment using murine melanoma cells demonstrates that PAH levels in cells were affected by melanin, suggesting the affinity of melanin to PAHs. Both biomonitoring and cell exposure experiment implicate the pivotal role of melanin in PAH accumulation in hair. Therefore, to ensure the accuracy of hair biomonitoring for MOCs, attention must be paid to the melanin content uniformity.

The non-redundant functions of PIWI family proteins in gametogenesis in golden hamsters.

The piRNA pathway is essential for female fertility in golden hamsters and likely humans, but not in mice. However, the role of individual PIWIs in mammalian reproduction remains poorly understood outside of mice. Here, we describe the expression profiles, subcellular localization, and knockout-associated reproductive defects for all four PIWIs in golden hamsters. In female golden hamsters, PIWIL1 and PIWIL3 are highly expressed throughout oogenesis and early embryogenesis, while knockout of PIWIL1 leads to sterility, and PIWIL3 deficiency results in subfertility with lagging zygotic development. PIWIL1 can partially compensate for TE silencing in PIWIL3 knockout females, but not vice versa. PIWIL1 and PIWIL4 are the predominant PIWIs expressed in adult and postnatal testes, respectively, while PIWIL2 is present at both stages. Loss of any PIWI expressed in testes leads to sterility and severe but distinct spermatogenesis disorders. These findings illustrate the non-redundant regulatory functions of PIWI-piRNAs in gametogenesis and early embryogenesis in golden hamsters, facilitating study of their role in human fertility.

Single-cell transcriptome reveals dominant subgenome expression and transcriptional response to heat stress in Chinese cabbage.

BACKGROUND: Chinese cabbage (Brassica rapa ssp. pekinensis) experienced a whole-genome triplication event and thus has three subgenomes: least fractioned, medium fractioned, and most fractioned subgenome. Environmental changes affect leaf development, which in turn influence the yield. To improve the yield and resistance to different climate scenarios, a comprehensive understanding of leaf development is required including insights into the full diversity of cell types and transcriptional networks underlying their specificity. RESULTS: Here, we generate the transcriptional landscape of Chinese cabbage leaf at single-cell resolution by performing single-cell RNA sequencing of 30,000 individual cells. We characterize seven major cell types with 19 transcriptionally distinct cell clusters based on the expression of the reported marker genes. We find that genes in the least fractioned subgenome are predominantly expressed compared with those in the medium and most fractioned subgenomes in different cell types. Moreover, we generate a single-cell transcriptional map of leaves in response to high temperature. We find that heat stress not only affects gene expression in a cell type-specific manner but also impacts subgenome dominance. CONCLUSIONS: Our study highlights the transcriptional networks in different cell types and provides a better understanding of transcriptional regulation during leaf development and transcriptional response to heat stress in Chinese cabbage.

Organophosphate flame retardants and diesters in the urine of e-waste dismantling workers: associations with indoor dust and implications for urinary biomonitoring.

Indoor dust ingestion is one of the main pathways for human exposure to organophosphate flame retardants (PFRs). The urinary concentrations of diesters (DAPs) are usually used as biomarkers to assess human exposure to PFRs. In this study, the PFR and DAP levels were measured in morning and evening urine samples of 30 workers from an e-waste dismantling site in southern China. The indoor dust samples were also collected from workshops and houses for analyzing associations between PFR and DAP levels in urine and dust. Tris(1-chloro-2-propyl) phosphate (TCIPP) and triphenyl phosphate (TPHP) were the dominant PFRs in dust, while bis(2-chloroethyl) phosphate (BCEP) and diphenyl phosphate (DPHP) were the major DAPs in dust. A significant positive correlation was observed between TPHP and DPHP concentrations in dust (p < 0.001), suggesting their potentially same source and the degradation of TPHP to form DPHP. TCIPP and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the predominant PFRs, and BCEP, bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and DPHP were the main DAPs in both the morning and evening urine samples. The DPHP levels in evening urine samples were significantly correlated with TPHP and DPHP levels (p < 0.01) in dust. A similar correlation was found for the BCEP levels in the evening urine samples and the TCEP and BCEP levels (p < 0.01) in dust. These results indicated that in addition to being biotransformed from their respective parent PFRs, direct ingestion from indoor dust could also be the potential source for urinary DPHP and BCEP. Since relatively low detection frequencies were observed for bis(1-chloro-2-propyl) phosphate (BCIPP) and bis(butoxyethyl) phosphate (BBOEP) in urine, they may not be the major metabolites of TCIPP and tris(2-butoxyethyl) phosphate (TBOEP), respectively, in the human body. However, BDCIPP can be considered a useful biomarker because it is a unique metabolite of TDCIPP and has high detection frequencies in urine samples. The results of this study indicated the limitations of solely using urinary DAPs as biomarkers for the evaluation of human exposure to PFRs, and certain PFRs as well as hydroxylated PFRs (OH-PFRs) should also be considered for urinary biomonitoring in future studies.

[A new nor-sesquiterpene from Cassia occidentalis and its bioactivity].

The phytochemistry investigation on the Cassia occidentalis, a Dai Medicine, was carried out. The C. occidentalis was extracted with ethanol and then partitioned with EtOAc. The EtOAc soluble materials were subjected repeatedly to column chromatography on silica gel and preparative RP-HPLC, leading to isolation of a nor-sesquiterpene, 3-isopropyl-1,6-dimethoxy-5-methyl-naphthalen-7-ol (1), and a sesquiterpene, 2,7-dihydroxy-4-isopropyl-6-methyl-naphthalene-1-carbaldehyde (2). Their structures were determined by means of spectroscopic studies. Compound 1 is a new compound. Compound 2 is also isolated from C. occidentalis for the first time. In addition, the cytotoxicity of compound 1 for NB4, A549, SHSY5Y, PC3, and MCF7 cells line was assayed by using the MTT method, and it displayed potential cytotoxicity for the tested cancer cell-line with IC50 valves of (1.8±0.2), (1.2±0.2), (0.9±0.1), (2.2±0.3), (2.6±0.3) µmol•L⁻¹, respectively.