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North Richmond, CA, United States

Sercu B.,University of California at Santa Barbara | Jones A.D.G.,ENVIRON International Corporation | Wu C.H.,Lawrence Berkeley National Laboratory | Wu C.H.,Food and Drug Laboratory Branch | And 6 more authors.
Microbial Ecology | Year: 2013

In situ chemical oxidation with permanganate has become an accepted remedial treatment for groundwater contaminated with chlorinated solvents. This study focuses on the immediate and short-term effects of sodium permanganate (NaMnO4) on the indigenous subsurface microbial community composition in groundwater impacted by trichloroethylene (TCE). Planktonic and biofilm microbial communities were studied using groundwater grab samples and reticulated vitreous carbon passive samplers, respectively. Microbial community composition was analyzed by terminal restriction fragment length polymorphism and a high-density phylogenetic microarray (PhyloChip). Significant reductions in microbial diversity and biomass were shown during NaMnO4 exposure, followed by recovery within several weeks after the oxidant concentrations decreased to <1 mg/L. Bray-Curtis similarities and nonmetric multidimensional scaling showed that microbial community composition before and after NaMnO4 was similar, when taking into account the natural variation of the microbial communities. Also, 16S rRNA genes of two reductive dechlorinators (Desulfuromonas spp. and Sulfurospirillum spp.) and diverse taxa capable of cometabolic TCE oxidation were detected in similar quantities by PhyloChip across all monitoring wells, irrespective of NaMnO4 exposure and TCE concentrations. However, minimal biodegradation of TCE was observed in this study, based on oxidized conditions, concentration patterns of chlorinated and nonchlorinated hydrocarbons, geochemistry, and spatiotemporal distribution of TCE-degrading bacteria. © 2012 Springer Science+Business Media, LLC.

She J.,Environmental Health Laboratory Branch | She Y.,Food and Drug Laboratory Branch | Song W.,Food and Drug Laboratory Branch
Science China Chemistry | Year: 2010

In an effort to investigate the status of human exposure to PBDEs in China, available monitoring data in human specimens (including breast milk, serums, and blood) was collected from the general population as well as specific groups that are occupationally exposed. PBDEs exposure profiles and concentration levels were compared with their counterparts in the United States of America. It was found that PBDE burdens in general Chinese population are one order lower and have different congener profiles from that in the US, showing higher percentages of BDE-28 or BDE-153 in human specimens from China. Workers and residents in electronic wastes recycling regions or areas of commercial PBDE manufacturing have the highest PBDE exposure levels reported worldwide, which are close or higher than the exposure levels of the general population in the US. Highly brominated congeners, such as BDE-207 and 209, are among the major PBDE congeners, and BDE-209 has the highest percentage (above 50%) for all occupational populations studied. Principal components analysis (PCA) demonstrates that the exposure of the general population in the US is closely related to penta-BDE while the human burden in China is not. The PBDE in indoor air (gas phase) in the US is highly correlated with the PBDE burden in the general population in the US, indicating a major exposure pathway. For the occupationally exposed populations in China, the congener profiles are closely related to the commercial deca-BDE products. Examination of exposure profiles for general and occupational populations in China suggests that it is essential to include more highly brominated congeners, such as BDE-207 and 209, in future human exposure studies, in order to assess the real burdens and profiles of PBDEs exposure in China. Strict pollution prevention and occupational protection procedures are in need in China to avoid the PBDE contamination problem that has occurred in the US. © Science China Press and Springer-Verlag Berlin Heidelberg 2010.

English P.,California Environmental Health Tracking Program | Blount B.,Centers for Disease Control and Prevention | Wong M.,California Environmental Health Tracking Program | Copan L.,Environmental Health Investigations Branch | And 5 more authors.
PLoS ONE | Year: 2011

Exposure to perchlorate is ubiquitous in the United States and has been found to be widespread in food and drinking water. People living in the lower Colorado River region may have perchlorate exposure because of perchlorate in ground water and locally-grown produce. Relatively high doses of perchlorate can inhibit iodine uptake and impair thyroid function, and thus could impair neurological development in utero. We examined human exposures to perchlorate in the Imperial Valley among individuals consuming locally grown produce and compared perchlorate exposure doses to state and federal reference doses. We collected 24-hour urine specimen from a convenience sample of 31 individuals and measured urinary excretion rates of perchlorate, thiocyanate, nitrate, and iodide. In addition, drinking water and local produce were also sampled for perchlorate. All but two of the water samples tested negative for perchlorate. Perchlorate levels in 79 produce samples ranged from non-detect to 1816 ppb. Estimated perchlorate doses ranged from 0.02 to 0.51 μg/kg of body weight/day. Perchlorate dose increased with the number of servings of dairy products consumed and with estimated perchlorate levels in produce consumed. The geometric mean perchlorate dose was 70% higher than for the NHANES reference population. Our sample of 31 Imperial Valley residents had higher perchlorate dose levels compared with national reference ranges. Although none of our exposure estimates exceeded the U. S. EPA reference dose, three participants exceeded the acceptable daily dose as defined by bench mark dose methods used by the California Office of Environmental Health Hazard Assessment.

Abromaitis S.,University of California at San Francisco | Abromaitis S.,Food and Drug Laboratory Branch | Nelson C.S.,University of California at San Francisco | Previte D.,University of Massachusetts Amherst | And 5 more authors.
PLoS ONE | Year: 2013

The bacterial pathogen Bartonella quintana is passed between humans by body lice. B. quintana has adapted to both the human host and body louse vector niches, producing persistent infection with high titer bacterial loads in both the host (up to 105 colony-forming units [CFU]/ml) and vector (more than 108 CFU/ml). Using a novel custom microarray platform, we analyzed bacterial transcription at temperatures corresponding to the host (37°C) and vector (28°C), to probe for temperature-specific and growth phase-specific transcriptomes. We observed that transcription of 7% (93 genes) of the B. quintana genome is modified in response to change in growth phase, and that 5% (68 genes) of the genome is temperature-responsive. Among these transcriptional changes in response to temperature shift and growth phase was the induction of known B. quintana virulence genes and several previously unannotated genes. Hemin binding proteins, secretion systems, response regulators, and genes for invasion and cell attachment were prominent among the differentially-regulated B. quintana genes. This study represents the first analysis of global transcriptional responses by B. quintana. In addition, the in vivo experiments provide novel insight into the B. quintana transcriptional program within the body louse environment. These data and approaches will facilitate study of the adaptation mechanisms employed by Bartonella during the transition between human host and arthropod vector. © 2013 Abromaitis et al.

Abromaitis S.,University of California at San Francisco | Abromaitis S.,Food and Drug Laboratory Branch | Koehler J.E.,University of California at San Francisco
Journal of Bacteriology | Year: 2013

Bartonella quintana is a vector-borne bacterial pathogen that causes fatal disease in humans. During the infectious cycle, B. quintana transitions from the hemin-restricted human bloodstream to the hemin-rich body louse vector. Because extracytoplasmic function (ECF) sigma factors often regulate adaptation to environmental changes, we hypothesized that a previously unstudied B. quintana ECF sigma factor, RpoE, is involved in the transition from the human host to the body louse vector. Thegenomic context of B. quintana rpoE identified it as a member of the ECF15 family of sigma factors found only in alphaproteobacteria. ECF15 sigma factors are believed to be the master regulators of the general stress response in alphaproteobacteria. Inthis study, we examined the B. quintana RpoE response to two stressors that are encountered in the body louse vector environment, a decreased temperature and an increased hemin concentration. We determined that the expression of rpoE is significantly upregulated at the body louse (28°C) versus the human host (37°C) temperature. rpoE expression also was upregulated when B.quintana was exposed to high hemin concentrations. In vitro and in vivo analyses demonstrated that RpoE function is regulated by a mechanism involving the anti-sigma factor NepR and the response regulator PhyR. The δrpoE δnepR mutant strain of B.quintana established that RpoE-mediated transcription is important in mediating the tolerance of B. quintana to high heminconcentrations. We present the first analysis of an ECF15 sigma factor in a vector-borne human pathogen and conclude thatRpoE has a role in the adaptation of B. quintana to the hemin-rich arthropod vector environment. © 2013, American Society for Microbiology.

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