Self-generated oxygen gradients control collective aggregation of photosynthetic microbes.

For billions of years, photosynthetic microbes have evolved under the variable exposure to sunlight in diverse ecosystems and microhabitats all over our planet. Their abilities to dynamically respond to alterations of the luminous intensity, including phototaxis, surface association and diurnal cell cycles, are pivotal for their survival. If these strategies fail in the absence of light, the microbes can still sustain essential metabolic functionalities and motility by switching their energy production from photosynthesis to oxygen respiration.

Flood-induced transport of PAHs from streambed coal tar deposits.

We assessed whether coal tar present in contaminated streambed sediments can be mobilized by flood events and be re-deposited in an adjacent floodplain. The study was conducted within a contaminated urban stream where coal tar wastes were released into a 4-km reach from a coke plant in Chattanooga, Tennessee, USA. Sediments containing visible amounts of coal tar were dredged from the streambed in 1997-98 and 2007 as part of a cleanup effort.

Standardized application of yeast bioluminescent reporters as endocrine disruptor screen for comparative analysis of wastewater effluents from membrane bioreactor and traditional activated sludge.

A standardized protocol is demonstrated for bioluminescent strains Saccharomyces cerevisiae BLYES, BLYAS and BLYR as high-throughput screening tools to monitor the estrogenic, androgenic and toxic potencies in wastewater. The sensitivity and reproducibility of the assay in wastewater monitoring was evaluated for 7 day semi-continuous batch reactor using activated sludge with hormones spiked raw sewage. Yeast bioluminescent assay successfully captured the rapid removal of estrogenic and androgenic activities in the bioreactors, and demonstrated rapid response (≤4 h) with good reproducibility.

Extraction of 3,4,4'-Trichlorocarbanilide from Rat Fecal Samples for Determination by High Pressure Liquid Chromatography-Tandem Mass Spectrometry.

Triclocarban (3,4,4'-Trichlorocarbanilide; TCC) in the environment has been well documented. Methods have been developed to monitor TCC levels from various matrices including water, sediment, biosolids, plants, blood and urine; however, no method has been developed to document the concentration of TCC in fecal content after oral exposure in animal studies. In the present study, we developed and validated a method that uses liquid extraction coupled with HPLC-MS/MS determination to measure TCC in feces.

Early life triclocarban exposure during lactation affects neonate rat survival.

Triclocarban (3,4,4'-trichlorocarbanilide; TCC), an antimicrobial used in bar soaps, affects endocrine function in vitro and in vivo. This study investigates whether TCC exposure during early life affects the trajectory of fetal and/or neonatal development. Sprague Dawley rats were provided control, 0.

A computational approach predicting CYP450 metabolism and estrogenic activity of an endocrine disrupting compound (PCB-30).

Endocrine disrupting chemicals influence growth and development through interactions with the hormone system, often through binding to hormone receptors such as the estrogen receptor. Computational methods can predict endocrine disrupting chemical activity of unmodified compounds, but approaches predicting activity following metabolism are lacking. The present study uses a well-known environmental contaminant, PCB-30 (2,4,6-trichlorobiphenyl), as a prototype endocrine disrupting chemical and integrates predictive (computational) and experimental methods to determine its metabolic transformation by cytochrome P450 3A4 (CYP3A4) and cytochrome P450 2D6 (CYP2D6) into estrogenic byproducts.

C60 reduces the bioavailability of mercury in aqueous solutions.

The effects of C60 on mercury bioavailability and sorption were investigated at different C60 dosages, reaction times, and pH ranges using the merR::luxCDABE bioluminescent bioreporter Escherichia coli ARL1. The results demonstrated that the bioavailability of mercury (Hg(2+)) decreased with increasing C60 dosage. Approximately 30% of aqueous mercury became biologically unavailable 2h after interaction with C60 at a mass ratio of C60 to mercury as low as 0.

Lack of androgenicity and estrogenicity of the three monomers used in Eastman's Tritan™ copolyesters.

Eastman Tritan™ copolyester, a novel plastic from Eastman is manufactured utilizing three monomers, di-methylterephthalate (DMT), 1,4-cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) in various ratios. As with most any polymer, the monomers along with the high molecular weight oligomers, whose toxicity is most commonly represented by the monomers, make up the predominate amount of free chemicals available for leaching into the environment and/or foods. In light of the high level of public concern about the presence of endocrine (primarily estrogenic) activity ascribed to certain plastics and chemicals in the environment, Tritan's™ monomers were evaluated using QSAR for binding to the androgen receptor and estrogen receptors (alpha and beta) as well as a battery of in vitro and in vivo techniques to determine their potential androgenicity or estrogenicity.

Detection of dichloromethane with a bioluminescent (lux) bacterial bioreporter.

The focus of this research effort was to develop an autonomous, inducible, lux-based bioluminescent bioreporter for the real-time detection of dichloromethane. Dichloromethane (DCM), also known as methylene chloride, is a volatile organic compound and one of the most commonly used halogenated solvents in the U.S.

Activation of group IVC phospholipase A(2) by polycyclic aromatic hydrocarbons induces apoptosis of human coronary artery endothelial cells.

Exposure to environmental pollutants, such as polycyclic aromatic hydrocarbons (PAHs) found in coal tar mixtures and tobacco sources, is considered a significant risk factor for the development of heart disease in humans. The goal of this study was to determine the influence of PAHs present at a Superfund site on human coronary artery endothelial cell (HCAEC) phospholipase A(2) (PLA(2)) activity and apoptosis. Extremely high levels of 12 out of 15 EPA high-priority PAHs were present in both the streambed and floodplain sediments at a site where an urban creek and its adjacent floodplain were extensively contaminated by PAHs and other coal tar compounds.

The association between nC60 and 17α-ethinylestradiol (EE2) decreases EE2 bioavailability in zebrafish and alters nanoaggregate characteristics.

Manufactured nanoparticles (NPs) released into surface waters will associate with other substances and these interactions may affect environmental fate and bioavailability of NPs and the associated substances. We investigated the association between aqueous aggregates of C(60) (nC(60)) and synthetic estrogen, 17α-ethinylestradiol (EE2), and considered nC(60) physicochemistry and EE2 bioavailability (by measuring vitellogenin (vtg1A/B) gene expression) in zebrafish. Bioavailability of EE2 was reduced with increasing concentration of nC(60) (P < 0.

No bioavailability of 17α-ethinylestradiol when associated with nC60 aggregates during dietary exposure in adult male zebrafish (Danio rerio).

The C(60) fullerene is a manufactured carbon nanoparticle (CNP) that could pose a risk to humans and other organisms after release into the environment. In surface waters, C(60) is likely to be present as aggregates of nC(60) and these aggregates can associate with other substances that are toxic. Our goal was to evaluate the association of a model contaminant [17α-ethinylestradiol (EE2)] with nC(60) and determine bioavailability of EE2 after accumulation by a filter feeding organism [Brine shrimp (BS) Artemia sp.

Phosphatidylserine synthase and phosphatidylserine decarboxylase are essential for cell wall integrity and virulence in Candida albicans.

Phospholipid biosynthetic pathways play crucial roles in the virulence of several pathogens; however, little is known about how phospholipid synthesis affects pathogenesis in fungi such as Candida albicans. A C. albicans phosphatidylserine (PS) synthase mutant, cho1 Delta/Delta, lacks PS, has decreased phosphatidylethanolamine (PE), and is avirulent in a mouse model of systemic candidiasis.

Attributing effects of aqueous C60 nano-aggregates to tetrahydrofuran decomposition products in larval zebrafish by assessment of gene expression.

Background: C(60) is a highly insoluble nanoparticle that can form colloidal suspended aggregates in water, which may lead to environmental exposure in aquatic organisms. Previous research has indicated toxicity from C(60) aggregate; however, effects could be because of tetrahydrofuran (THF) vehicle used to prepare aggregates.

Objective: Our goal was to investigate changes in survival and gene expression in larval zebrafish Danio rerio after exposure to aggregates of C(60) prepared by two methods: a) stirring and sonication of C(60) in water (C(60)-water); and b) suspension of C(60) in THF followed by rotovaping, resuspension in water, and sparging with nitrogen gas (THF-C(60)).

Distribution and transport of coal tar-derived PAHs in fine-grained residuum.

We investigated the distribution and transport of coal tar-derived polycyclic aromatic hydrocarbons (PAHs) in fine-grained residuum and alluvial floodplain deposits that underlie a former manufactured gas plant. All 16 USEPA priority pollutant PAHs are present at this site and have penetrated the entire 4-5m thickness of clayey sediments, which unconformably overly limestone bedrock. Concentrations of less hydrophobic PAHs (e.

Disposition of genistein in rainbow trout (Oncorhynchus mykiss) and siberian sturgeon (Acipenser baeri).

Genistein (G) is a xenoestrogen from soy present in fish diet. In vivo, a 50-fold difference in sensitivity to genistein on vitellogenin (VTG) synthesis was found when comparing trout and sturgeon. This difference was not linked to the estrogen receptor affinity nor to the sensitivity of induction of the VTG pathway.

Tilapia (Oreochromis niloticus) vitellogenins: development of homologous and heterologous ELISAs and analysis of vitellogenin pathway through the ovarian follicle.

Vitellogenin (VTG) of Oreochromis niloticus was again purified, due to the conflicting results found in the literature. Three purification processes have been used: electrophoresis and electro-elution, double chromatography (gel filtration and ion-exchange chromatography) and single ion-exchange chromatography. Using SDS-PAGE we confirmed in all cases the presence of two polypeptidic forms of plasma VTG of 130 kDa (VTG1) and 170 kDa (VTG2).

Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil.

Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3.

Abundance of dioxygenase genes similar to Ralstonia sp. strain U2 nagAc is correlated with naphthalene concentrations in coal tar-contaminated freshwater sediments.

We designed a real-time PCR assay able to recognize dioxygenase large-subunit gene sequences with more than 90% similarity to the Ralstonia sp. strain U2 nagAc gene (nagAc-like gene sequences) in order to study the importance of organisms carrying these genes in the biodegradation of naphthalene. Sequencing of PCR products indicated that this real-time PCR assay was specific and able to detect a variety of nagAc-like gene sequences.

Binding affinities of hepatic nuclear estrogen receptors for phytoestrogens in rainbow trout (Oncorhynchus mykiss) and Siberian sturgeon (Acipenser baeri).

Phytoestrogens are dietary estrogenic contaminants capable of inducing vitellogenin synthesis in rainbow trout and Siberian sturgeon. A competitive-binding assay on their hepatic estrogen receptors (ER) was performed to determine the relative affinity of phytoestrogens compared to estradiol (E(2)). Phytoestrogen concentrations used were 1000 times higher than for E(2), except for genistein and formononetin.

Effects of dietary phytoestrogens in vivo and in vitro in rainbow trout and Siberian sturgeon: interests and limits of the in vitro studies of interspecies differences.

A study of the effects of dietary genistein on trout and sturgeon in vivo showed that sturgeon was sensitive to 20 ppm of genistein, whereas trout was not. To analyze the origin of this interspecies difference in sensitivity, a cell culture technique was developed with hepatocytes from sturgeon and compared to results obtained with hepatocytes from trout in the same system. The hepatocyte culture proved to be useful as bioassay for estrogenicity.

[Comparison of the effects of gonadotropic preparations of the carp and stellate sturgeon pituitaries on in vivo and in vitro oocyte maturation in the Siberian sturgeon Acipenser baeri brandt].

Injections of 2.5 mg/kg of stellate sturgeon (Acipenser stellatus Pall.) pituitary extract and 5 mg/kg of carp (Cyprinus carpio L.

Effect of genistein-enriched diets on the endocrine process of gametogenesis and on reproduction efficiency of the rainbow trout Oncorhynchus mykiss.

Three practical diets were formulated to contain 0, 500, or 1000 ppm genistein. The three diets were distributed for 1 year to groups of rainbow trout undergoing their first gametogenesis and until spawning. Growth performance of rainbow trout was not affected by dietary treatments.

Seasonal variations and maturity stages in relation to differences in serum levels of gonadal steroids, vitellogenin, and thyroid hormones in the common dentex (Dentex dentex).

Seasonal variations in serum concentrations of 17beta-estradiol (E(2)), vitellogenin (Vg), testosterone (T), 11 ketotestosterone (11-KT), and thyroid hormones (T(4), l-thyroxine; and T(3), 3,5, 3'-triiodo-l-thyronine) were investigated during the first, second, and third reproductive cycles in intensively reared populations of common dentex, Dentex dentex, and correlated with gonadal development and spawning. In females, there were baseline E(2) values (<0.10 ng/ml) and negligible Vg concentrations during the postspawning and pregametogenesis period (June to December), and these increased thereafter to peak during the spawning period.

Synthesis of haptens and conjugates for ELISAs of phytoestrogens. Development of the immunological tests.

Seven carboxylic acid haptens of isoflavonoids were synthesized, with the spacer arm on the oxygen atom at the C7 position for one series, with formononetin, daidzein, equol, biochanin A, and genistein, and at the C8 position for a second series, with only formononetin and daidzein. The different haptens were coupled to bovine serum albumin (BSA) and to swine thyroglobulin (Thyr). Polyclonal antibodies were generated against the BSA conjugates.