Chemical Transformations of 2D Kaolinic Clay Mineral Surfaces from Sulfuric Acid Exposure.

A combined experimental and computational approach is used to investigate the chemical transformations of kaolinite and metakaolin surfaces when exposed to sulfuric acid. These clay minerals are hydrated ternary metal oxides and are shown to be susceptible to degradation by loss of Al as the water-soluble salt Al2(SO4)3, due to interactions between H2SO4 and aluminum cations. This degradation process results in a silica-rich interfacial layer on the surfaces of the aluminosilicates, most prominently observed in metakaolin exposed to pH environments of less than 4. Our observations are supported by XPS, ATR-FTIR, and XRD experiments. Concurrently, DFT methodologies are used to probe the interactions between the clay mineral surfaces and H2SO4 as well as other sulfur-containing adsorbates. An analysis performed using a DFT + thermodynamics model shows that the surface transformation processes that lead to the loss of Al and SO4 from metakaolin are favorable at pH below 4; however, such transformations are not favorable for kaolinite, a result that agrees with our experimental efforts. The data obtained from both experimental techniques and computational studies support that the dehydrated surface of metakaolin interacts more strongly with sulfuric acid and provide atomistic insight into the acid-induced transformations of these mineral surfaces.

Volatile organic compounds emitted by filamentous fungi isolated from flooded homes after Hurricane Sandy show toxicity in a Drosophila bioassay.

Superstorm Sandy provided an opportunity to study filamentous fungi (molds) associated with winter storm damage. We collected 36 morphologically distinct fungal isolates from flooded buildings. By combining traditional morphological and cultural characters with an analysis of ITS sequences (the fungal DNA barcode), we identified 24 fungal species that belong to eight genera: Penicillium (11 species), Fusarium (four species), Aspergillus (three species), Trichoderma (two species), and one species each of Metarhizium, Mucor, Pestalotiopsis, and Umbelopsis. Then, we used a Drosophila larval assay to assess possible toxicity of volatile organic compounds (VOCs) emitted by these molds. When cultured in a shared atmosphere with growing cultures of molds isolated after Hurricane Sandy, larval toxicity ranged from 15 to 80%. VOCs from Aspergillus niger 129B were the most toxic yielding 80% mortality to Drosophila after 12 days. The VOCs from Trichoderma longibrachiatum 117, Mucor racemosus 138a, and Metarhizium anisopliae 124 were relatively non-toxigenic. A preliminary analysis of VOCs was conducted using solid-phase microextraction-gas chromatography-mass spectrometry from two of the most toxic, two of the least toxic, and two species of intermediate toxicity. The more toxic molds produced higher concentrations of 1-octen-3-ol, 3-octanone, 3-octanol, 2-octen-1-ol, and 2-nonanone; while the less toxic molds produced more 3-methyl-1-butanol and 2-methyl-1-propanol, or an overall lower amount of volatiles. Our data support the hypothesis that at certain concentrations, some VOCs emitted by indoor molds are toxigenic.

Aspergillus: a primer for the novice.

Aspergillus is a genus of molds named after the morphological structure that bears asexual spores, the aspergillum, which resembles a liturgical device. This genus contains several species of positive or negative economic importance in industry, agriculture and medicine. The majority of aspergilli, including most species of economic importance, are known to reproduce only by asexual spores. Genome projects have been completed for A. fumigatus, A. nidulans, A. niger and A. oryzae; several other species are also being sequenced. The data from these genome projects have been useful in elucidating aspects of phylogeny, the evolution of sexuality and the extent of secondary metabolite diversity. To date, however, the impact on drug discovery, diagnosis of aspergillosis, and our understanding of fungal pathogenesis has been less pronounced.

Dose enhancement effects to the nucleus and mitochondria from gold nanoparticles in the cytosol.

Gold nanoparticles (GNPs) have shown potential as dose enhancers for radiation therapy. Since damage to the genome affects the viability of a cell, it is generally assumed that GNPs have to localise within the cell nucleus. In practice, however, GNPs tend to localise in the cytoplasm yet still appear to have a dose enhancing effect on the cell. Whether this effect can be attributed to stress-induced biological mechanisms or to physical damage to extra-nuclear cellular targets is still unclear. There is however growing evidence to suggest that the cellular response to radiation can also be influenced by indirect processes induced when the nucleus is not directly targeted by radiation. The mitochondrion in particular may be an effective extra-nuclear radiation target given its many important functional roles in the cell. To more accurately predict the physical effect of radiation within different cell organelles, we measured the full chemical composition of a whole human lymphocytic JURKAT cell as well as two separate organelles; the cell nucleus and the mitochondrion. The experimental measurements found that all three biological materials had similar ionisation energies ∼70 eV, substantially lower than that of liquid water ∼78 eV. Monte Carlo simulations for 10-50 keV incident photons showed higher energy deposition and ionisation numbers in the cell and organelle materials compared to liquid water. Adding a 1% mass fraction of gold to each material increased the energy deposition by a factor of ∼1.8 when averaged over all incident photon energies. Simulations of a realistic compartmentalised cell show that the presence of gold in the cytosol increases the energy deposition in the mitochondrial volume more than within the nuclear volume. We find this is due to sub-micron delocalisation of energy by photoelectrons, making the mitochondria a potentially viable indirect radiation target for GNPs that localise to the cytosol.

Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing.

Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with (110 m)Ag showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 µg/kg (0.002-3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability.

Nonrandom chromosome structural aberrations and oncogene loci in human malignant melanoma.

Short-term cultures of 10 malignant melanomas derived from 8 patients were analyzed cytogenetically. The chromosome composition of the tumors was found to be similar in terms of modal number and structural and numerical aberrations, especially the nonrandom nature of breakpoints. Six chromosomes were consistently involved in marker formation. Aberrations of chromosomes #1 and #9 were identified in every tumor, whereas structural alterations of chromosome #2 were found in 9 tumors. In contrast, aberrations of chromosomes #6, #3, and #7 were identified in 7, 7, and 8 of the tumors, respectively. The nonrandom breakpoints on these chromosomes frequently coincided with known oncogenic loci and resulted in morphologically identical marker chromosomes. Consecutive lesions were obtained for two patients. Common markers were identified in both cases, indicating the clonal origin of the tumors. In addition, many marker chromosomes characteristic of the individual lesions were also identified. The presence of these lesion-specific markers indicates the nonrandom selective nature of the metastatic process and suggests the possible heterogeneity of the original tumor cell population.

Na+/Ca2+ exchange activity is increased in Alzheimer's disease brain tissues.

These studies were performed to determine the changes that occur in Na+/Ca2+ exchange activity in Alzheimer's disease (AD) brain tissues. Cerebral plasma membrane vesicles were purified by sucrose density gradient centrifugation from frozen postmortem hippocampal/temporal cortex tissue slices derived from age matched brains of normal, AD and non-Alzheimer dementia (NAD) origin (autopsy confirmed). Membrane marker assays (Na/K ATPase, muscarinic receptor, cytochrome c oxidase) revealed no change in membrane purity across different preparations. Thin-section electron microscopy revealed predominantly intact unilamellar vesicles. Vesicles were preincubated for 15 min (37 degrees C) in buffer containing 132 mM NaCl, 5 mM KCl, 1.3 mM MgCl2, 10 mM glucose and 10 mM HEPES (pH 7.4). Ca2+ uptake was initiated by diluting vesicles 20-fold with buffer containing either 132 mM NaCl or 132 mM choline chloride and 45CaCl2 then terminated by addition of 200 microM LaCl3 and rapid filtration. Ca2+ content increased rapidly at first and then maintained a steady plateau for up to 5 min. When the Ca2+ ionophore A23187 (10 microM) with 100 microM EGTA was added after 4 min, Ca2+ content was reduced to 10% of its original value. Ruthenium red (10 microM) had no effect on Ca2+ content. Na(+)-dependent Ca2+ uptake (Ca2+ content measured in choline chloride minus that measured in NaCl) was increased in AD brains as evidenced by both an increase in the initial rise in Ca2+ content and in elevated values of peak plateau Ca2+ content.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophoretic karyotype analysis in fungi.

The resolution of chromosomal-sized DNAs by PFGE has many applications that include karyotyping, strain identification of similar species, characterization of transformed strains, building of linkage maps, and preparation of DNA for genomic analysis. Successful electrophoretic separation of chromosomes is an empiric process in which the initial concentration of intact chromosome-sized DNA and the optimization of electrophoretic parameters are the most important experimental variables. Nonetheless, inherent attributes of the genome architecture of certain species may thwart success. When a karyotype contains numerous chromosomes of the same size and/or many large (greater than 8 Mb) chromosomes, no amount of manipulation of the electrophoretic parameters will resolve individual chromosome bands using present technology. Further, fungi display a surprising amount of intraspecific variation in both chromosome number and size, making it difficult to establish a standard "reference" karyotype for many species. Although PFGE is not a panacea for bringing genetics to species that lack classical genetic systems, it often does provide a way for developing a molecular linkage map in the absence of a formal genetic system. It is far faster than parasexual analysis in the discovery of linkage relationships. For genomics projects, DNA can be recovered from pulsed field gels and used to prepare chromosome-specific libraries. Where whole genome sequencing strategies are used, chromosomes separated by PFGE provide an anchor for sequencing data. Electrophoretic karyotypes can be probed with anonymous pieces of DNA from bacterial artificial chromosome (BAC) contigs, thereby facilitating the building of physical maps. In conclusion, despite its shortcomings, the PFGE technique underlies much of our current understanding of the physical nature of the fungal genome.

Mycotechnology: the role of fungi in biotechnology.

Fungi have been important in both ancient and modern biotechnological processes. Processes and products that utilize fungi include baking, brewing, and the production of antibiotics, alcohols, enzymes, organic acids, and numerous pharmaceuticals. The advent of recombinant DNA technology and large scale genomics analysis has placed yeasts and filamentous fungi in the forefront of contemporary commercial applications. The term 'mycotechnology' is introduced here to describe the enormous impact of fungi on biotechnology.

A new sterigmatocystin-producing Emericella variant from agricultural desert soils.

An unusual, sterigmatocystin-producing taxon with characteristics of both Emericella nidulans (anamorph Aspergillus nidulans) and Emericella rugulosa (anamorph Aspergillus rugulovalvus, formerly A. rugulosus) was isolated repeatedly during a mycofloral survey of desert cotton field soils where aflatoxin is a chronic problem. Members of this taxon had ascospores with smooth convex walls like E. nidulans but grew slowly like E. rugulosa; moreover, they were similar to an industrial echinocandin B-producing strain which had been classified as "Aspergillus nidulans var. roseus." These new desert isolates were compared with "A. nidulans var. roseus" and representative wild-type isolates of E. nidulans and E. rugulosa using traditional morphological characters, secondary metabolite profiles of mycelial extracts, and Southern blot analysis of genomic DNA. The desert isolates and "A. nidulans var. roseus shared morphological, physiological and molecular characters with E. rugulosa. These isolates constitute a new non-rugulose variant of E. rugulosa.

A comparison of enumeration techniques for Cryptosporidium parvum oocysts.

A variety of methods have been used to enumerate Cryptosporidium parvum oocysts from source or drinking waters. The reliability of these counting methods varies, in part, with suspension density, sample purity, and other factors. Frequently, the method of determination of suspension density is not reported by authors. To confound the problem, each method of counting has large inherent variation. There is a relationship between suspension density, overall number of organisms counted, and counting mechanism accuracy that should be accounted for when selecting a counting mechanism. This study selected a maximum acceptable coefficient of variation (CV) to be 10%. A method was considered unreliable if this standard was not achieved. Flow cytometry achieved this standard at 486 oocysts/ml. Counting with a Coulter counter achieved this level of reliability at about 1,230 oocysts/ml. Neither chamber slides nor fluorescent antibody-stained well slides ever demonstrated less than 10% CV. However, estimates of the minimum required concentrations were 5,100 oocysts/ml and approximately 6,500 oocysts/ml, respectively. The hemacytometer provided counts accurate to a 10% CV at a concentration of at least 60,000 organisms/ml. Of the methods tested, flow cytometry provided the least amount of variability at low suspension densities.

Mineralization of benzo[a]pyrene by Marasmiellus troyanus, a mushroom isolated from a toxic waste site.

Mycelia from the mushroom Marasmiellus troyanus were grown in the presence of radiolabeled benzo[a]pyrene in liquid culture. After 15 days, 8.1% of the label from M. troyanus cultures was recovered in CO2 as compared to 1.1% for Phanerochaete chrysosporium and 0.2% for Aspergillus niger. M. troyanus efficiently transformed B[a]P into water soluble metabolites with 64% of the label recovered in the water soluble fraction as compared to 11.7% for P. chrysosporium and 4.1% for A. niger. Glucuronic acid and sulfate conjugates of B[a]P were identified from the aqueous fraction of cultures of M. troyanus, after 17 days.

Testing methods for detection of Cryptosporidium spp in water samples.

A large waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, USA in 1993 prompted a search for ways to prevent large-scale waterborne outbreaks of protozoan parasitoses. Methods for detecting Cryptosporidium parvum play an integral role in strategies that lead to appropriate treatment of surface water, but are criticized because they produce results that are highly variable. The US Environmental Protection Agency developed a set of criteria to evaluate detection methods for protozoan parasites in water. As a consequence, the Agency has had to develop approaches to reducing uncertainty of evaluations. The variability and accuracy of various methods of producing small numbers of Cryptosporidium spp oocysts were tested. The least variable and most accurate method was used to spike seven surface water, and one tap water sample to compare 4 detection methods that had been reported in the literature. The least variable and most accurate method for spiking specified numbers of oocysts into samples was found to be flow cytometry. The most effective of the methods tested for detection in surface, tap and reagent water was solid phase cytometry.

The touch inventory for elementary-school-aged children: test-retest reliability and mother-child correlations.

OBJECTIVE: The Touch Inventory for Elementary-School-Aged Children (TIE) is a self-report screening assessment for tactile defensiveness. The purpose of this study was to examine test-retest reliability of the TIE and to evaluate agreement between children's TIE scores and scores that mothers gave their children on a modified version of the TIE. METHOD: Twenty-nine children, 6 to 12 years of age, were available for the test-retest portion of the study and were assessed with the TIE with a 1-week interval between sessions. Their mothers completed a modified version of the TIE. RESULTS: Results indicated significant test-retest reliability (r = .91, p < .001), although a more conservative Kappa indicated only moderate agreement. The correlation between mothers' ratings and children's ratings was less significant (r = .56, p = .001), and Kappas were slight or fair, indicating considerable disagreement between mothers and children. CONCLUSION: These results suggest that using information from both mothers and children might provide a more complete picture of tactile defensiveness, but further research is needed before using a mother's assessment when the TIE is implemented as a standard procedure.

Live attenuated malaria vaccine designed to protect through hepatic CD8⁺ T cell immunity.

Our goal is to develop a vaccine that sustainably prevents Plasmodium falciparum (Pf) malaria in ≥80% of recipients. Pf sporozoites (PfSPZ) administered by mosquito bites are the only immunogens shown to induce such protection in humans. Such protection is thought to be mediated by CD8(+) T cells in the liver that secrete interferon-γ (IFN-γ). We report that purified irradiated PfSPZ administered to 80 volunteers by needle inoculation in the skin was safe, but suboptimally immunogenic and protective. Animal studies demonstrated that intravenous immunization was critical for inducing a high frequency of PfSPZ-specific CD8(+), IFN-γ-producing T cells in the liver (nonhuman primates, mice) and conferring protection (mice). Our results suggest that intravenous administration of this vaccine will lead to the prevention of infection with Pf malaria.