BackgroundC60 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 C60 aggregate; however, effects could be because of tetrahydrofuran (THF) vehicle used to prepare aggregates.ObjectiveOur goal was to investigate changes in survival and gene expression in larval zebrafish Danio rerio after exposure to aggregates of C60 prepared by two methods: a) stirring and sonication of C60 in water (C60–water); and b) suspension of C60 in THF followed by rotovaping, resuspension in water, and sparging with nitrogen gas (THF–C60).ResultsSurvival of larval zebrafish was reduced in THF–C60 and THF–water but not in C60–water. The greatest differences in gene expression were observed in fish exposed to THF–C60 and most (182) of these genes were similarly expressed in fish exposed to THF–water. Significant up-regulation (3- to 7-fold) of genes involved in controlling oxidative damage was observed after exposure to THF–C60 and THF–water. Analyses of THF–C60 and THF–water by gas chromatography–mass spectrometry did not detect THF but found THF oxidation products γ-butyrolactone and tetrahydro-2-furanol. Toxicity of γ-butyrolactone (72-hr lethal concentration predicted to kill 50% was 47 ppm) indicated effects in THF treatments can result from γ-butyrolactone toxicity.ConclusionThis research is the first to link toxic effects directly to a THF degradation product (γ-butyrolactone) rather than to C60 and may explain toxicity attributed to C60 in other investigations. The present work was first presented at the meeting “Overcoming Obstacles to Effective Research Design in Nanotoxicology” held 24–26 April 2006 in Cambridge, Massachusetts, USA.

A strong immunoreactivity for ferritin was observed in the neuritic (senile) plaques in Alzheimer's disease hippocampus. The ferritin accumulation was almost exclusively associated with the microglia, which appeared to have proliferated greatly. These cells were also positive for HLA-DR, a putative marker for reactive microglia. In contrast, in the diffuse plaques, which were without neuritic pathology, the ferritin-stained microglia appeared to be normal. Microglia were seen frequently in contact with neurons undergoing neurofibrillary changes but only the tangles in the extracellular space were ferritin positive. No ferritin was detected, by Western blots, in paired helical filaments isolated from Alzheimer's disease brain, suggesting that ferritin was most likely weakly associated with and was not a constituent of these fibrils. No correlation between increased ferritin/microglia activity and blood-brain barrier leakage was detected. Ferritin, an iron-storage protein, might have a role in the formation of amyloid through the action of free radicals generated during the release of iron from the ferritin molecule. Alternatively, the ferritin/microglia system might be secondarily involved in the removal and processing of the amyloid.

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Ferritin was isolated from the livers and brains of two groups of rats, one of which was fed aluminum chloride (100 ,uM) for 1 year in the drinking water. Brain tissue contained about one-third ofthe amount offerritin found in the liver. While brain ferritin from normal rats contained 42.1 ± 14.3 mol of aluminum, that from the aluminum-fed group contained 115.4 ± 48.3 mol of aluminum per mol of ferritin. Liver ferritin from both groups contained similar amounts of both aluminum and iron, and the amounts were less than that found associated with brain ferritin. Ferritin isolated from the brains of patients who died of Alzheimer disease contained more aluminum and more iron than that from age-matched controls. Human brain ferritin is composed of two types of subunits-about 70% heavy chain (Mr, 22,000) and 30% light chain (Mr,19,500). The isoelectric focusing pattern of human brain ferritin was considerably different from that of human liver. Only 5 of the 20 brain ferritin bands migrated similarly to the acidic isoferritins from the liver, and the major component of brain ferritin, representing 30% of the total ferritin, had a pI of 8.0.

Traditional methods for quantifying specific catabolic bacterial populations underestimate the true population count due to the limitations of the necessary laboratory cultivation methods. Likewise, in situ activity is also difficult to assess in the laboratory without altering the sample environment. To circumvent these problems and achieve a true in situ bacterial population count and activity measurement, new methods based on molecular biological analysis of bacterial nucleic acids were applied to soils heavily contaminated with polycyclic aromatic hydrocarbons (PAH). In addition, a naphthalene-lux reporter system was used to determine bioavailability of naphthalene within these soils. DNA extracted from seven PAH-contaminated soils and hybridized with the nahA gene probe indicated that the naphthalene degradative genes were present in all samples in the range of 0.06 to 0.95 ng/100 microliters DNA extract which was calculated to represent 3.2 x 10(6) to 1.1 x 10(10) cells/g soil (assuming one copy of these genes per cell). 14C-naphthalene mineralization was observed in all contaminated soils with 14CO2 mineralization rates ranging from 3.2 x 10(-5) to 304,920.0 x 10(-5) micrograms g soil-1 h-1. Phenanthrene, anthracene, and benzo(a)pyrene were mineralized also in several soils. Messenger RNA transcripts of nahA were isolated and quantified from 4 soils. Only one soil tested, soil B, was inducible with salicylate above the in situ nahA gene transcript level. Two of the soils, C and G, were already fully induced in situ. The naphthalene mineralization rate correlated positively with the amount of nahA gene transcripts present (r = 0.99). Naphthalene was bioavailable in soils A, D, E, G, and N as determined by a bioluminescent response from the naphthalene-lux reporter system. Taken together, these data provided information on what the naphthalene-degrading bacterial population was experiencing in situ and what approaches would be necessary to increase activity.

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Depleted uranium (DU) is a by-product of the uranium enrichment process and shares chemical properties with natural and enriched uranium. To investigate the toxic effects of environmental DU exposure on the immune system, we examined the influences of DU (in the form of uranyl nitrate) on viability and immune function as well as cytokine gene expression in murine peritoneal macrophages and splenic CD4+ T cells. Macrophages and CD4+ T cells were exposed to various concentrations of DU, and cell death via apoptosis and necrosis was analyzed using annexin-V/propidium iodide assay. DU cytotoxicity in both cell types was concentration dependent, with macrophage apoptosis and necrosis occurring within 24 hr at 100 μM DU exposure, whereas CD4+ T cells underwent cell death at 500 μM DU exposure. Noncytotoxic concentrations for macrophages and CD4+ T cells were determined as 50 and 100 μM, respectively. Lymphoproliferation analysis indicated that macrophage accessory cell function was altered with 200 μM DU after exposure times as short as 2 hr. Microarray and real-time reverse-transcriptase polymerase chain reaction analyses revealed that DU alters gene expression patterns in both cell types. The most differentially expressed genes were related to signal transduction, such as c-jun, NF-κ Bp65, neurotrophic factors (e.g., Mdk), chemokine and chemokine receptors (e.g., TECK/CCL25), and interleukins such as IL-10 and IL-5, indicating a possible involvement of DU in cancer development, autoimmune diseases, and T helper 2 polarization of T cells. The results are a first step in identifying molecular targets for the toxicity of DU and the elucidation of the molecular mechanisms for the immune modulation ability of DU.