air-sampled-filter-analysis-for-endotoxins-and-dna-content

Air-sampled Filter Analysis for Endotoxins and DNA Content

Outdoor aerosol research commonly uses particulate matter sampled on filters. This procedure enables various characterizations of the collected particles ...

Weizmann Institute of Science

Max Planck Institute

Atmospheric aerosols scatter and absorb solar radiation leading to variable effects on Earth's radiative balance. Aerosols individually comprising mixtures of different components ("internally mixed") interact differently with light than mixtures of aerosols, each comprising a different single component ("externally mixed"), even if the relative fractions of the different components are equal. In climate models, the optical properties of internally mixed aerosols are generally calculated by using electromagnetic "mixing rules", which average the refractive indices of the individual components in different proportions, or by using coated-sphere Mie scattering codes, which solve the full light scattering problem assuming that the components are divided into two distinct layers. Because these calculation approaches are in common use, it is important to validate them experimentally. In this article, we present a broad perspective on the optical properties of internally mixed aerosols based on a series of laboratory experiments and theoretical calculations. The optical properties of homogenously mixed aerosols comprised of non-absorbing and weakly absorbing compounds, and of coated aerosols comprised of strongly absorbing, non-absorbing, and weakly absorbing compounds in different combinations are measured using pulsed and continuous wave cavity ring down aerosol spectrometry (CRD-AS). The success of electromagnetic mixing rules and Mie scattering codes in reproducing the measured aerosol extinction values is discussed.

Interaction of internally mixed aerosols with light.

Increased susceptibility to allergies has been documented in the Western world in recent decades. However, a comprehensive understanding of its causes is not yet available. It is therefore essential to understand trends and mechanisms of allergy-inducing agents, such as fungal conidia. In this study, we investigated the hypothesis that environmental conditions linked to global atmospheric changes can affect the allergenicity of Aspergillus fumigatus, a common allergenic fungal species in indoor and outdoor environments and in airborne particulate matter. We show that fungi grown under present-day CO2 levels (392 ppm) exhibit 8.5 and 3.5 fold higher allergenicity compared to fungi grown at preindustrial (280 ppm) and double (560 ppm) CO2 levels, respectively. A corresponding trend is observed in the expression of genes encoding for known allergenic proteins and in the major allergen Asp f1 concentrations, possibly due to physiological changes such as respiration rates and the nitrogen content of the fungus, influenced by the CO2 concentrations. Increased carbon and nitrogen levels in the growth medium also lead to a significant increase in the allergenicity. We propose that climatic changes such as increasing atmospheric CO2 levels and changes in the fungal growth medium may impact the ability of allergenic fungi such as A. fumigatus to induce allergies.

Changes in atmospheric CO2 influence the allergenicity of Aspergillus fumigatus.

Marine aerosols, that are very common in the highly populated coastal cities and communities, may contain biological constituents. Some of this biological fraction of marine aerosols, such as cyanobacteria and plankton debris, may influence human health by inflammation and allergic reactions when inhaled. In this study we identify and compare sources for endotoxins sampled on filters in an on-shore and more-inland site. Filter analysis included endotoxin content, total bacteria, gram-negative bacteria and cyanobacteria genome concentrations as well as ion content in order to identify possible sources for the endotoxins. Satellite images of chlorophyll-a levels and back trajectory analysis were used to further study the cyanobacteria blooms in the sea, close to the trajectory of the sampled air. The highest endotoxin concentrations found in the shoreline site were during winter (3.23±0.17 EU/m(3)), together with the highest cyanobacteria genome (1065.5 genome/m(3)). The elevated endotoxin concentrations were significantly correlated with cyanobacterial levels scaled to the presence of marine aerosol (r=0.90), as well as to chlorophyll-a (r=0.96). Filters sampled further inland showed lower and non-significant correlation between endotoxin and cyanobacteria (r=0.70, P value=0.19), suggesting decrease in marine-originated endotoxin, with possible contributions from other sources of gram-negative non-cyanobacteria. We conclude that marine cyanobacteria may be a dominant contributor to elevated endotoxin levels in coastal areas.

Marine aerosol as a possible source for endotoxins in coastal areas.

Understanding the chemical interactions of common allergens in urban environments may help to decipher the general increase in susceptibility to allergies observed in recent decades. In this study, asexual conidia of the allergenic mold Aspergillus fumigatus were exposed to air pollution under natural (ambient) and controlled (laboratory) conditions. The allergenic activity was measured using two immunoassays and supported by a protein mass spectrometry analysis. The allergenicity of the conidia was found to increase by 2-5 fold compared to the control for short exposure times of up to 12h (accumulated exposure of about 50 ppb NO2 and 750 ppb O3), possibly due to nitration. At higher exposure times, the allergenicity increase lessened due to protein deamidation. These results indicate that during the first 12h of exposure, the allergenic potency of the fungal allergen A. fumigatus in polluted urban environments is expected to increase. Additional work is needed in order to determine if this behavior occurs for other allergens.

Article	Year
Interaction of internally mixed aerosols with light. Physical chemistry chemical physics : PCCP\| PubMed ID: 20024440	2010
Changes in atmospheric CO2 influence the allergenicity of Aspergillus fumigatus. Global change biology\| PubMed ID: 23568517	2013
Marine aerosol as a possible source for endotoxins in coastal areas. The Science of the total environment\| PubMed ID: 25201818	2014
Impact of urban air pollution on the allergenicity of Aspergillus fumigatus conidia: Outdoor exposure study supported by laboratory experiments. The Science of the total environment\| PubMed ID: 26410711	2016

Naama Lang-Yona

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