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Applied and Environmental Microbiology Dec 2020Hexachlorobenzene (HCB), as one of the persistent organic pollutants (POPs) and a possible human carcinogen, is especially resistant to biodegradation. In this study,...
Hexachlorobenzene (HCB), as one of the persistent organic pollutants (POPs) and a possible human carcinogen, is especially resistant to biodegradation. In this study, HcbA1A3, a distinct flavin-N5-peroxide-utilizing enzyme and the sole known naturally occurring aerobic HCB dechlorinase, was biochemically characterized. Its apparent preference for HCB in binding affinity revealed that HcbA1 could oxidize only HCB rather than less-chlorinated benzenes such as pentachlorobenzene and tetrachlorobenzenes. In addition, the crystal structure of HcbA1 and its complex with flavin mononucleotide (FMN) were resolved, revealing HcbA1 to be a new member of the bacterial luciferase-like family. A much smaller substrate-binding pocket of HcbA1 than is seen with its close homologues suggests a requirement of limited space for catalysis. In the active center, Tyr362 and Asp315 are necessary in maintaining the normal conformation of HcbA1, while Arg311, Arg314, Phe10, Val59, and Met12 are pivotal for the substrate affinity. They are supposed to place HCB at a productive orientation through multiple interactions. His17, with its close contact with the site of oxidation of HCB, probably fixes the target chlorine atom and stabilizes reaction intermediates. The enzymatic characteristics and crystal structures reported here provide new insights into the substrate specificity and catalytic mechanism of HcbA1, which paves the way for its rational engineering and application in the bioremediation of HCB-polluted environments. As an endocrine disrupter and possible carcinogen to human beings, hexachlorobenzene (HCB) is especially resistant to biodegradation, largely due to difficulty in its dechlorination. The lack of knowledge of HCB dechlorinases limits their application in bioremediation. Recently, an HCB monooxygenase, HcbA1A3, representing the only naturally occurring aerobic HCB dechlorinase known so far, was reported. Here, we report its biochemical and structural characterization, providing new insights into its substrate selectivity and catalytic mechanism. This research also increases our understanding of HCB dechlorinases and flavin-N5-peroxide-utilizing enzymes.
Topics: Bacterial Proteins; Catalysis; Escherichia coli; Hexachlorobenzene; Microorganisms, Genetically-Modified; Mixed Function Oxygenases; Nocardioides; Substrate Specificity
PubMed: 33097503
DOI: 10.1128/AEM.01965-20 -
Environmental Health Perspectives Jan 1999Persistent organic pollutants (POPs) can travel thousands of miles, accumulate in the food chain, and persist in the environment, taking as long as centuries to degrade....
Persistent organic pollutants (POPs) can travel thousands of miles, accumulate in the food chain, and persist in the environment, taking as long as centuries to degrade. POPs are known to play a role in birth defects, cancer, immune system dysfunction, and reproductive problems in wildlife. While the effects of POPs on human health are unclear, many researchers believe that long-term exposure contributes to increasing rates of birth defects, fertility problems, greater susceptibility to disease, diminished intelligence, and certain cancers. Twelve POPs have been identified by the United Nations Environment Programme as requiring urgent regulatory attention. They include the pesticides aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, and toxaphene. Of the remaining three POPs, polychlorinated biphenyls are industrial products (used in electrical transformers), and dioxins and furans are unintentional by-products of industrial processes.
Topics: Aldrin; Chlordan; DDT; Dieldrin; Dioxins; Endrin; Environmental Exposure; Furans; Heptachlor; Hexachlorobenzene; Humans; Hydrocarbons, Chlorinated; Insecticides; Mirex; Polychlorinated Biphenyls; Toxaphene
PubMed: 9872725
DOI: 10.1289/ehp.99107a18 -
Frontiers in Endocrinology 2022There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause... (Review)
Review
There are many organochlorine pollutants in the environment, which can be directly or indirectly exposed to by mothers, and as estrogen endocrine disruptors can cause damage to the lactation capacity of the mammary gland. In addition, because breast milk contains a lot of nutrients, it is the most important food source for new-born babies. If mothers are exposed to organochlorine pesticides (OCPs), the lipophilic organochlorine contaminants can accumulate in breast milk fat and be passed to the infant through breast milk. Therefore, it is necessary to investigate organochlorine contaminants in human milk to estimate the health risks of these contaminants to breastfed infants. In addition, toxic substances in the mother can also be passed to the fetus through the placenta, which is also something we need to pay attention to. This article introduces several types of OCPs, such as dichlorodiphenyltrichloroethane (DDT), methoxychlor (MXC), hexachlorocyclohexane (HCH), endosulfan, chlordane, heptachlorand and hexachlorobenzene (HCB), mainly expounds their effects on women's lactation ability and infant health, and provides reference for maternal and infant health. In addition, some measures and methods for the control of organochlorine pollutants are also described here.
Topics: Environmental Pollutants; Female; Humans; Hydrocarbons, Chlorinated; Infant; Milk, Human; Pesticide Residues; Pesticides; Pregnancy
PubMed: 35757428
DOI: 10.3389/fendo.2022.890307 -
International Journal of Environmental... Mar 2022To identify bioaccumulation patterns of α-, β- hexachlorocyclohexane (HCH) and dicofol in relation to sociodemographic, dietary, and lifestyle factors, adipose tissue...
To identify bioaccumulation patterns of α-, β- hexachlorocyclohexane (HCH) and dicofol in relation to sociodemographic, dietary, and lifestyle factors, adipose tissue samples of 387 subjects from GraMo cohort in Southern Spain were analyzed. Potential predictors of these organochlorine pesticides (OCP) levels were collected by face-to-face interviews and assessed by multivariable linear and logistic regression. OCPs were detected in 84.2% (β-HCH), 21.7% (α-HCH), and 19.6% (dicofol) of the population. β-HCH levels were positively related to age, body mass index (BMI), mother's occupation in agriculture during pregnancy, living in Poniente and Alpujarras, white fish, milk and water consumption, and negatively related to being male, living near to an agricultural area, working ≥10 years in agriculture, and beer consumption. Detectable α-HCH levels were positively related to age, BMI, milk consumption, mother's occupation in agriculture during pregnancy, and negatively with residence in Poniente and Alpujarras, Granada city, and Granada Metropolitan Area. Residence near to an agricultural area, smoking habit, white fish and water consumption, and living in Poniente and Alpujarras, Granada city and Granada Metropolitan Area were negatively associated with detectable dicofol levels. Our study revealed different bioaccumulation patterns of α, β-HCH and dicofol, probably due to their dissimilar period of use, and emphasize the need for assessing the exposure to frequently overlooked pollutants.
Topics: Adipose Tissue; Animals; Bioaccumulation; Dicofol; Female; Hexachlorocyclohexane; Humans; Hydrocarbons, Chlorinated; Male; Pesticides; Pregnancy; Spain
PubMed: 35329028
DOI: 10.3390/ijerph19063344 -
Molecules (Basel, Switzerland) Jun 2023A diverse spectrum of organisms, such as fungi, bacteria, and actinomycetes, can degrade and transform organic matter, including wood, into valuable nutrients. A... (Review)
Review
A diverse spectrum of organisms, such as fungi, bacteria, and actinomycetes, can degrade and transform organic matter, including wood, into valuable nutrients. A sustainable economy has the goal of efficiently using waste as raw materials, and in this optic, it uses biological preparations more and more often, supporting the decomposition of lignocellulosic waste. With reference to wood wastes, which are produced in a substantial amount by the forest and wood industry, one of the possibilities to biodegrade such lignocellulosic material is the composting process. In particular, microbiological inoculum containing dedicated fungi can contribute to the biodegradation of wood waste, as well as the biotransformation of substances from the protection of wood, such as pentachlorophenol (PCP), lindane (hexachlorobenzene) and polycyclic aromatic hydrocarbons (PAHs). The purpose of this research was to produce a literature review in terms of the selection of decay fungi that could potentially be used in toxic biotransformation unions. The findings of the literature review highlighted how fungi such as , , and might be ingredients of biological consortia that can be effectively applied in composting wood waste containing substances such as pentachlorophenol, lindane, and polycyclic aromatic hydrocarbons (PAHs).
Topics: Trametes; Pentachlorophenol; Wood; Hexachlorocyclohexane; Biotransformation; Biodegradation, Environmental; Polycyclic Aromatic Hydrocarbons
PubMed: 37375379
DOI: 10.3390/molecules28124823 -
Frontiers in Endocrinology 2022Multiple studies have shown associations between exposure to endocrine disrupting chemicals (EDCs) and reduced fertility in women. However, little is known about the...
Multiple studies have shown associations between exposure to endocrine disrupting chemicals (EDCs) and reduced fertility in women. However, little is known about the target organs of chemical disruption of female fertility. Here, we focus on the hormone-sensitive uterine lining, the endometrium, as a potential target. Decidualization is the morphological and functional change that endometrial stromal cells undergo to support endometrial receptivity, which is crucial for successful implantation, placentation, and pregnancy. We investigated the effect of nine selected EDCs on primary human endometrial stromal cell decidualization The cells were exposed to a decidualization-inducing mixture in the presence or absence of 1 μM of nine different EDCs for nine days. Extent of decidualization was assessed by measuring the activity of cAMP dependent protein kinase, Rho-associated coiled-coil containing protein kinase, and protein kinase B in lysates using photoluminescent probes, and secretion of prolactin into the media by using ELISA. Decidualization-inducing mixture upregulated activity of protein kinases and prolactin secretion in cells derived from all women. Of the tested chemicals, dichlorodiphenyldichloroethylene (p,p'-DDE), hexachlorobenzene (HCB) and perfluorooctanesulfonic acid (PFOS) significantly reduced decidualization as judged by the kinase markers and prolactin secretion. In addition, bisphenol A (BPA) reduced prolactin secretion but did not significantly affect activity of the kinases. None of the EDCs was cytotoxic, based on the assessment of total protein content or activity of the viability marker casein kinase 2 in lysates. These results indicate that EDCs commonly present in the blood circulation of reproductive-aged women can reduce decidualization of human endometrial stromal cells . Future studies should focus on detailed hazard assessment to define possible risks of EDC exposure to endometrial dysfunction and implantation failure in women.
Topics: Adult; Cells, Cultured; Decidua; Endocrine Disruptors; Female; Humans; Insulin-Like Growth Factor Binding Protein 1; Pregnancy; Prolactin; Stromal Cells
PubMed: 36060944
DOI: 10.3389/fendo.2022.903505 -
Report on Carcinogens : Carcinogen... 2011
Topics: Animals; Carcinogens; Coloring Agents; Environmental Exposure; Fungicides, Industrial; Government Regulation; Hexachlorobenzene; Humans; United States
PubMed: 21852845
DOI: No ID Found -
Current Environmental Health Reports Dec 2018Endocrine disrupting chemicals (EDCs) potentially have a role in causing hypospadias malformation through modifiable in-utero exposure. Considering the emerging... (Review)
Review
PURPOSE OF REVIEW
Endocrine disrupting chemicals (EDCs) potentially have a role in causing hypospadias malformation through modifiable in-utero exposure. Considering the emerging literature on the role of potential endocrine disrupting substances on the occurrence of hypospadias and the potential to inform public health efforts to prevent the occurrence of these malformations, we have summarized the current literature, identified areas of consensus, and highlighted areas that warrant further investigation.
RECENT FINDINGS
Pharmaceuticals, such as diethylstilbestrol, progestin fertility treatments, corticosteroids, and valproic acid, have all been associated with hypospadias risk. Data on exposure to dichlorodiphenyltrichloroethane and hexachlorobenzene pesticides, as well as non-persistent pollutants, particularly phthalates, is less consistent but still compelling. Improving exposure assessment, standardizing sample timing to relevant developmental windows, using clear case identification and classification schemes, and elucidating dose-response relationships with EDCs will help to provide clearer evidence. Promising directions for future research include identification of subgroups with genetic hypospadias risk factors, measurement of intermediate outcomes, and study of EDC mixtures that will more accurately represent the total fetal environment.
Topics: Endocrine Disruptors; Environmental Exposure; Environmental Pollutants; Female; Hexachlorobenzene; Humans; Hydrocarbons, Chlorinated; Hypospadias; Infant; Male; Occupational Exposure; Pesticides; Pregnancy; Prenatal Exposure Delayed Effects
PubMed: 30578470
DOI: 10.1007/s40572-018-0214-z -
Current Opinion in Pediatrics Apr 2008Although environmental levels of polychlorinated biphenyls and certain organochlorine pesticides--hexachlorobenzene, dichlorodiphenyl trichloroethane and its primary... (Review)
Review
PURPOSE OF REVIEW
Although environmental levels of polychlorinated biphenyls and certain organochlorine pesticides--hexachlorobenzene, dichlorodiphenyl trichloroethane and its primary metabolite, dichlorodiphenyl dichloroethene--are generally on the decline, early-life exposures to these prevalent contaminants continue. The review will describe current understanding of the potential neurodevelopmental consequences of low-level exposures to these contaminants.
RECENT FINDINGS
Animal models suggest that early-life exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene or hexachlorobenzene are associated with decreased cognitive or behavioral function in later development. Despite almost 30 years of research, however, results of human studies are inconsistent regarding the nature of the observed effects and their persistence over time. Overall, epidemiologic studies support modest associations of primarily prenatal polychlorinated biphenyl exposures with differences in neuromotor development, decrements in cognition and behavioral deficits, particularly regarding attention and impulse control. There are limited published human data regarding potential neurodevelopmental toxicities of early-life exposures to dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene.
SUMMARY
Exposures to polychlorinated biphenyls, dichlorodiphenyl trichloroethane/dichlorodiphenyl dichloroethene and hexachlorobenzene are likely detrimental to neurodevelopment. Effective control of exposure is complicated by variable exposure sources and variable contaminant levels in food, particularly fish, for which it is important to balance the risk of contaminants with nutritional benefits.
Topics: Child; Child Behavior Disorders; Cohort Studies; Developmental Disabilities; Environmental Exposure; Environmental Pollutants; Female; Hexachlorobenzene; Humans; Neuropsychological Tests; Pesticides; Polychlorinated Biphenyls; Pregnancy; Prenatal Exposure Delayed Effects; Prospective Studies
PubMed: 18332718
DOI: 10.1097/MOP.0b013e3282f6a4e9