Biology subjects

Maltz, M. R.

Publications and source records attributed to Maltz, M. R..

5 recordsLinked to original sources

bioRxiv2025

Lung microbiomes variable responses to dust exposure

Inhalation of dust is significant and relevant to health effects. As pollution and climate change worsen in dryland regions, wind currents entrain loose sediment and dust. This potentially disperses toxic geochemical and microbial burdens throughout the region. When inhaled environmental dust and host-associated microbiomes mingle, they pose exposure risks to host respiratory health. The Salton Sea, Californias largest lake, is shrinking thus exposing nearby communities to playa dust. Therefore, we analyze the effect of Salton Sea dust exposure in murine models to relate lung microbial communities and respiratory health. We used an environmental chamber to expose mice to dust filtrate or ambient air and examined the effects of those exposures on lung microbiomes. We found that lung microbial composition varied by dust exposure. Furthermore, dust elicited neutrophil recruitment and immune responses more than mice exposed to ambient air. Sources of dust differentially affected the composition of the lung core microbiome. Lung microbial diversity correlated with neutrophil recruitment as lungs associated with inflammatory responses harbored more diverse microbiomes. Although Salton Sea dust influences dust microbiomes and prevalent taxa, these responses were variable. The composition of lungs exposed to dust collected further from the Sea was more similar to lungs from ambient air exposures; in contrast, dust collected near the Sea yielded lung microbiomes that clustered further from lungs exposed to ambient air. As lakes continue to dry out, we expect greater public health risks in proximal dryland regions, which may correlate with dust microbial dispersal-related changes to lung microbiomes. ImportanceDust inhalation can lead to health effects, especially when toxic chemicals and microbes mix in with the dust particles. As Californias Salton Sea dries up, it exposes lake bottom sediments to wind, which disperses the dried sediments. To mimic the effect of inhaling Salton Sea dust, we collected and filtered airborne dust to use in exposure experiments with mice in environmental chambers. We predicted that inhaling small dust particles, chemicals, and microbial residues found in this dust would affect mouse respiratory health, or change the microbes found inside their lungs. We found that inhaling dust led to lung inflammation and the dust source influenced the type of microbes found inside mouse lungs. As lakes continue to dry out, we expect greater health risks and changes to lung microbiomes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/648223v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@11e791eorg.highwire.dtl.DTLVardef@1a1a853org.highwire.dtl.DTLVardef@31ee4aorg.highwire.dtl.DTLVardef@135f40_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2022

Aerosolized Desert Dusts Collected Near a Drying Lake and Pulmonary Inflammation in Mice: Implications for Environmental Exposures and Asthma

BackgroundA high incidence of asthma is prevalent among residents near the Salton Sea, a large inland terminal lake in southern California. This arid region has high levels of ambient particulate matter (PM); yet while high PM levels are often associated with asthma in many environments, it is possible that the rapidly retreating lake may contribute components with a specific role in promoting asthma symptoms. ObjectivesOur hypothesis is that asthma may be higher in residents closest to the Salton Sea due to chronic exposures to playa dust. Playa emissions may be concentrating dissolved material from the lake, with microbial components capable of inducing pulmonary innate immune responses. Such inflammatory responses may contribute to the development of asthma-like symptoms in residents. To test this hypothesis, we used a mouse model of aerosol exposures to assess the effects of playa dust. MethodsFrom dust collected around the Salton Sea region, aqueous extracts were used to generate aerosols, which were injected into an environmental chamber for mouse exposure studies. We compared the effects of exposure to Salton Sea aerosols, as well as to known immunostimulatory reference materials. Acute 48-hour and chronic 7-day exposures were compared, with lungs analyzed for inflammatory cell recruitment and gene expression. ResultsDust from sites nearest to the Salton Sea triggered lung neutrophil inflammation that was stronger at 48-hours but reduced at 7-days. This acute inflammatory profile and kinetics resembled the response to innate immune ligands LTA and LPS while distinct from the classic allergic response to Alternaria. ConclusionLung inflammatory responses to Salton Sea dusts are similar to acute innate immune responses, raising the possibility that microbial components are entrained in the dust, promoting inflammation. This effect highlights the health risks at drying terminal lakes from inflammatory components in dust emissions from exposed lakebed.

pharmacology and toxicology↗

bioRxiv2019

Ecological and genomic attributes of novel bacterial taxa that thrive in subsurface soil horizons

While most bacterial and archaeal taxa living in surface soils remain undescribed, this problem is exacerbated in deeper soils owing to the unique oligotrophic conditions found in the subsurface. Additionally, previous studies of soil microbiomes have focused almost exclusively on surface soils, even though the microbes living in deeper soils also play critical roles in a wide range of biogeochemical processes. We examined soils collected from 20 distinct profiles across the U.S. to characterize the bacterial and archaeal communities that live in subsurface soils and to determine whether there are consistent changes in soil microbial communities with depth across a wide range of soil and environmental conditions. We found that bacterial and archaeal diversity generally decreased with depth, as did the degree of similarity of microbial communities to those found in surface horizons. We observed five phyla that consistently increased in relative abundance with depth across our soil profiles: Chloroflexi, Nitrospirae, Euryarchaeota, and candidate phyla GAL15 and Dormibacteraeota (formerly AD3). Leveraging the unusually high abundance of Dormibacteraeota at depth, we assembled genomes representative of this candidate phylum and identified traits that are likely to be beneficial in low nutrient environments, including the synthesis and storage of carbohydrates, the potential to use carbon monoxide (CO) as a supplemental energy source, and the ability to form spores. Together these attributes likely allow members of the candidate phylum Dormibacteraeota to flourish in deeper soils and provide insight into the survival and growth strategies employed by the microbes that thrive in oligotrophic soil environments.\n\nImportanceSoil profiles are rarely homogeneous. Resource availability and microbial abundances typically decrease with soil depth, but microbes found in deeper horizons are still important components of terrestrial ecosystems. By studying 20 soil profiles across the U.S., we documented consistent changes in soil bacterial and archaeal communities with depth. Deeper soils harbored distinct communities compared to the more commonly studied surface horizons. Most notably, we found that the candidate phylum Dormibacteraeota (formerly AD3) was often dominant in subsurface soils, and we used genomes from uncultivated members of this group to identify why these taxa are able to thrive in such resource-limited environments. Simply digging deeper into soil can reveal a surprising amount of novel microbes with unique adaptations to oligotrophic subsurface conditions.

microbiology↗

bioRxiv2018

Inoculation with Pisolithus tinctorius may ameliorate acid rain impacts on soil microbial communities associated with Pinus massoniana seedlings

Human activities accelerate acidification, particularly as acid rain, which may have lasting impacts on soil abiotic and biotic parameters. However, the effects of acidification on aboveground vegetation, belowground communities, and carbon cycling remains unresolved. We examined the effects of long-term acidic treatments and Pisolithus inoculation on plants, soils, and microbial communities in pine plantations and found that exposure to severely-acidic treatments diminished plant performance, altered microbial communities, and decreased organic matter, nitrate, and available phosphorus. Although we did not detect any benefits of Pisolithus inoculation for Pinus seedlings impacted by severely-acidic treatments, when these severe treatments were inoculated with Pisolithus, both soil properties and microbial community composition shifted. We posit that inoculation with Pisolithus may alleviate stressful environmental conditions, and change the structure of mycorrhizal fungal communities. Although acidification may alter biogeochemical cycles and constrain aboveground and belowground communities, Pisolithus inoculation may provide benefits to some components of forested ecosystems.

ecology↗

bioRxiv2018

Establishment and Characterization of a Multi-Purpose Large Animal Exposure Chamber for Investigating Health Effects

Air pollution poses a significant threat to the environment and human health. Most in-vivo health studies conducted regarding air pollutants, including particulate matter (PM) and gas phase pollutants, have been either through traditional medical intranasal treatment or using a tiny chamber, which limit animal activities. In this study, we designed and tested a large, whole-body, multiple animal exposure chamber with uniform dispersion and exposure stability for animal studies. The chamber simultaneously controls particle size distribution and PM mass concentration. Two different methods were used to generate aerosol suspension through either soluble material (Alternaria extract), liquid particle suspension (Nanosilica solution) or dry powder (silica powder). We demonstrate that the chamber system provides well controlled and characterized whole animal exposures, where dosage is by inhalation of particulate matter.

bioengineering↗