High-density genetic map construction and identification of a locus controlling weeping trait in an ornamental woody plant (Prunus mume Sieb. et Zucc).

High-density genetic map is a valuable tool for fine mapping locus controlling a specific trait especially for perennial woody plants. In this study, we firstly constructed a high-density genetic map of mei (Prunus mume) using SLAF markers, developed by specific locus amplified fragment sequencing (SLAF-seq). The linkage map contains 8,007 markers, with a mean marker distance of 0.195 cM, making it the densest genetic map for the genus Prunus. Though weeping trees are used worldwide as landscape plants, little is known about weeping controlling gene(s) (Pl). To test the utility of the high-density genetic map, we did fine-scale mapping of this important ornamental trait. In total, three statistic methods were performed progressively based on the result of inheritance analysis. Quantitative trait loci (QTL) analysis initially revealed that a locus on linkage group 7 was strongly responsible for weeping trait. Mutmap-like strategy and extreme linkage analysis were then applied to fine map this locus within 1.14 cM. Bioinformatics analysis of the locus identified some candidate genes. The successful localization of weeping trait strongly indicates that the high-density map constructed using SLAF markers is a worthy reference for mapping important traits for woody plants.

Dietary and inhalation exposure to polycyclic aromatic hydrocarbons and urinary excretion of monohydroxy metabolites--a controlled case study in Beijing, China.

Daily dietary and inhalation exposures to 16 parent polycyclic aromatic hydrocarbons (PAHs) and urinary excretion of 13 monohydroxy metabolites (OHPAHs) were monitored for 12 non-smoking university students in Beijing, China, during a controlled feeding experiment. The relationship between the urinary excretion of OHPAHs and the uptake of PAHs was investigated. The results suggest severe exposure of the subjects to PAHs via both dietary and inhalation pathways. Large increase of most urinary OHPAHs occurred after the ingestion of lamb kabob. Higher concentrations of OHPAHs were observed for female subjects, with the intakes of parent PAHs lower than those by males, likely due to the gender differences in metabolism. It appears that besides 1-PYR, metabolites of PHE could also be used as biomarkers to indicate the short-term dietary exposure to PAHs and urinary 3-BaA may serve as the biomarker for inhalation intake of high molecular weight PAHs.

Occurrence and exposure to polycyclic aromatic hydrocarbons and their derivatives in a rural Chinese home through biomass fuelled cooking.

The concentration and composition of PAHs emitted from biomass cooking fuel were characterized in a rural non-smoking household in northern China. Twenty-two parent PAHs (pPAHs), 12 nitro-PAHs (nPAHs), and 4 oxy-PAHs (oPAHs) were measured in the kitchen, bedroom, and outdoors during both summer and winter. The most severe contamination occurred in the kitchen in the winter, where the daily mean concentrations of pPAHs, nPAHs, and oPAHs were 7500 ± 4100, 38 ± 29, and 8400 ± 9200 ng/m(3), respectively. Our results suggest that the nPAHs were largely from secondary formation in ambient air while oPAHs were either from primary emission of biomass burning or secondary formation from pPAHs in the kitchen. The daily mean benzo(a)pyrene equivalent exposure concentration was as high as 200 ± 160 ng/m(3) in the winter for the housewife who did the cooking compared to 59 ± 37 ng/m(3) for the control group that did not cook.

Cell absorption induced desorption of hydrophobic organic contaminants from digested soil residue.

Oral ingestion of contaminated soil is an important pathway of human exposure to hydrophobic organic contaminants (HOCs), particularly for children in developing countries. The mobilization potential of various contaminants from ingested soil is often characterized using an in vitro gastrointestinal model, based on the quantities of contaminants remaining in digestive fluid after digestion and separation. Recently, it was experimentally demonstrated that a large fraction of mobilized contaminants sorbed on the digested residue could be released if the dissolved fraction was removed by intestinal absorption. This hypothesis was further tested in this study. Soil spiked with dichlorodiphenyltrichloroethane and its metabolites (DDXs) and polycyclic aromatic hydrocarbons (PAHs) was digested using an in vitro gastrointestinal model. A human colon carcinoma cell line (Caco-2) was cultured in digestive fluid with or without soil residue (pre-equilibrated with the soil) for 2h. A large proportion of the contaminants (37-68%) was sorbed on the digested residue. Without this residue, 66±13% of DDXs and 73±14% of PAHs dissolved in the fluid, as means and standard deviations, were absorbed by the cell monolayer after exposure. With both digestive fluid and residue, the sorbed fraction of PAHs and DDXs decreased by 38-92%, while the ratios of the cellular to the dissolved concentrations were 2.7-2.8 times higher than those without the residue. This supported the hypothesis that the cell absorption of dissolved HOCs induces desorption of the sorbed fraction from digestive residue, and the desorbed HOCs can be absorbed as well.

Mobilization of soil-bound residue of organochlorine pesticides and polycyclic aromatic hydrocarbons in an in vitro gastrointestinal model.

A previous study on mobilization of organochlorine pesticides (OCPs) in contaminated soils from the field revealed that the total amount of OCPs measured in digestive fluid and chyme of an in vitro gastrointestinal model was higher than the quantity directly extracted using a solvent extraction without digestion, providing a clue that the bound residue of OCPs might be mobilized. This hypothesis was tested in this study for both OCPs and polycyclic aromatic hydrocarbons (PAHs). Three contaminated surface soil samples with different organic carbon (OC) contents were collected from the field, and extracted with a solvent with and without digestion in an in vitro gastrointestinal model. It was found that bound residues of OCPs and PAHs were mobilized to a certain extent during digestion. The ratios of the mobilized bound residues over the total quantities extracted after digestion (R(b)) varied from 0 to 0.96 for individual compounds. The R(b) was positively correlated with OC content. Among the five constitutes of digestive juice, bile salt was the only one that served to mobilize the bound residues and the extractability of bile salt was constant over a concentration range from 2 to 20 mg/mL. The mobilization process followed typical first-order kinetics. The calculated rate constants suggest that mobilization was fast and 90% of extracted bound residues of OCPs and PAHs were mobilized within 2.4 and 4.8 h, respectively.