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At least 487 records · Page 27Linked to original sources
USGS2006

Nonlinear inversion of potential-field data using a hybrid-encoding genetic algorithm

Using a genetic algorithm to solve an inverse problem of complex nonlinear geophysical equations is advantageous because it does not require computer gradients of models or "good" initial models. The multi-point search of a genetic algorithm makes it easier to find the globally optimal solution while avoiding falling into a local extremum. As is the case in other optimization approaches, the search efficiency for a genetic algorithm is vital in finding desired solutions successfully in a multi-dimensional model space. A binary-encoding genetic algorithm is hardly ever used to resolve an optimization problem such as a simple geophysical inversion with only three unknowns. The encoding mechanism, genetic operators, and population size of the genetic algorithm greatly affect search processes in the evolution. It is clear that improved operators and proper population size promote the convergence. Nevertheless, not all genetic operations perform perfectly while searching under either a uniform binary or a decimal encoding system. With the binary encoding mechanism, the crossover scheme may produce more new individuals than with the decimal encoding. On the other hand, the mutation scheme in a decimal encoding system will create new genes larger in scope than those in the binary encoding. This paper discusses approaches of exploiting the search potential of genetic operations in the two encoding systems and presents an approach with a hybrid-encoding mechanism, multi-point crossover, and dynamic population size for geophysical inversion. We present a method that is based on the routine in which the mutation operation is conducted in the decimal code and multi-point crossover operation in the binary code. The mix-encoding algorithm is called the hybrid-encoding genetic algorithm (HEGA). HEGA provides better genes with a higher probability by a mutation operator and improves genetic algorithms in resolving complicated geophysical inverse problems. Another significant result is that final solution is determined by the average model derived from multiple trials instead of one computation due to the randomness in a genetic algorithm procedure. These advantages were demonstrated by synthetic and real-world examples of inversion of potential-field data. ?? 2005 Elsevier Ltd. All rights reserved.

Computers & Geosciences↗
USGS2007

Peptidomic analysis of skin secretions supports separate species status for the tailed frogs, Ascaphus truei and Ascaphus montanus

The tailed frog Ascaphus truei Stejneger, 1899 is the most primitive extant anuran and the sister taxon to the clade of all other living frogs. The species occupies two disjunct ranges in the Northwest region of North America: the Cascade Mountains and coastal area from British Columbia to Northern California, and an inland range in the northern Rocky Mountains and the Blue and Wallowa mountains. A previous study led to the isolation of eight peptides with antimicrobial activity (termed the ascaphins) from skin secretions of A. truei from the coastal range. The present study has used peptidomic analysis to identify the products of orthologous ascaphin genes in electrically-stimulated skin secretions from inland range specimens. Structural characterization of the peptides demonstrated that ascaphins from the inland range contained the following amino acid substitutions compared with orthologs from the coastal range frogs: ascaphin-1 (Ala 12 → Glu), ascaphin-3 (Asp 4 → Glu), ascaphin-4 (Ala 19 → Ser), ascaphin-5 (Lys 12 → Thr), and ascaphin-7 (Gly 8 → Ser and Ser 20 → Asn). Orthologs of ascaphins-2, -6, and -8 were not identified but a paralog of ascaphin-5, identical to ascaphin-5 from coastal range frogs, was found. The data support the claims, derived from analysis of the nucleotide sequences of mitochondrial genes, that the inland populations of the tailed frog should be recognized as a distinct species, the Rocky Mountain tailed frog Ascaphus montanus and that the divergence of the species from A. truei probably occurred in the late Miocene (approximately 10 Mya).

Comparative Biochemistry and Physiology, Part D: G↗
USGS2017

Prior knowledge-based approach for associating contaminants with biological effects: A case study in the St. Croix River basin, MN, WI, USA

Evaluating potential adverse effects of complex chemical mixtures in the environment is challenging. One way to address that challenge is through more integrated analysis of chemical monitoring and biological effects data. In the present study, water samples from five locations near two municipal wastewater treatment plants in the St. Croix River basin, on the border of MN and WI, USA, were analyzed for 127 organic contaminants. Known chemical-gene interactions were used to develop site-specific knowledge assembly models (KAMs) and formulate hypotheses concerning possible biological effects associated with chemicals detected in water samples from each location. Additionally, hepatic gene expression data were collected for fathead minnows ( Pimephales promelas ) exposed in situ , for 12 d, at each location. Expression data from oligonucleotide microarrays were analyzed to identify functional annotation terms enriched among the differentially-expressed probes. The general nature of many of the terms made hypothesis formulation on the basis of the transcriptome-level response alone difficult. However, integrated analysis of the transcriptome data in the context of the site-specific KAMs allowed for evaluation of the likelihood of specific chemicals contributing to observed biological responses. Thirteen chemicals (atrazine, carbamazepine, metformin, thiabendazole, diazepam, cholesterol, p-cresol, phenytoin, omeprazole, ethyromycin, 17β-estradiol, cimetidine, and estrone), for which there was statistically significant concordance between occurrence at a site and expected biological response as represented in the KAM, were identified. While not definitive, the approach provides a line of evidence for evaluating potential cause-effect relationships between components of a complex mixture of contaminants and biological effects data, which can inform subsequent monitoring and investigation.

Minnesota, Wisconsin↗
USGS2018

Respiratory hazard assessment of combined exposure to complete gasoline exhaust and respirable volcanic ash in a multicellular human lung model at the air-liquid interface

Communities resident in urban areas located near active volcanoes can experience volcanic ash exposures during, and following, an eruption, in addition to sustained exposures to high concentrations of anthropogenic air pollutants ( e.g., vehicle exhaust emissions). Inhalation of anthropogenic pollution is known to cause the onset of, or exacerbate, respiratory and cardiovascular diseases. It is further postulated similar exposure to volcanic ash can also affect such disease states. Understanding of the impact of combined exposure of volcanic ash and anthropogenic pollution to human health, however, remains limited. The aim of this study was to assess the biological impact of combined exposure to respirable volcanic ash (from Soufrière Hills volcano (SHV), Montserrat and Chaitén volcano (ChV), Chile; representing different magmatic compositions and eruption styles) and freshly-generated complete exhaust from a gasoline vehicle. A multicellular human lung model (an epithelial cell-layer composed of A549 alveolar type II-like cells complemented with human blood monocyte-derived macrophages and dendritic cells cultured at the air-liquid interface) was exposed to diluted exhaust (1:10) continuously for 6 h, followed by immediate exposure to the ash as a dry powder (0.54 ± 0.19 μg/cm 2 and 0.39 ± 0.09 μg/cm 2 for SHV and ChV ash, respectively). After an 18 h incubation, cells were exposed again for 6 h to diluted exhaust, and a final 18 h incubation (at 37 °C and 5% CO 2 ). Cell cultures were then assessed for cytotoxic, oxidative stress and (pro-)inflammatory responses. Results indicate that, at all tested (sub-lethal) concentrations, co-exposures with both ash samples induced no significant expression of genes associated with oxidative stress ( HMOX1, NQO1 ) or production of (pro-)inflammatory markers (IL-1β, IL-8, TNF-α) at the gene and protein levels. In summary, considering the employed experimental conditions, combined exposure of volcanic ash and gasoline vehicle exhaust has a limited short-term biological impact to an advanced lung cell in vitro model.

Environmental Pollution↗
USGS2021

Effects-based monitoring of bioactive compounds associated with municipal wastewater treatment plant effluent discharge to the South Platte River, Colorado, USA

Previous studies have detected numerous organic contaminants and in vitro bioactivities in surface water from the South Platte River near Denver, Colorado, USA. To evaluate the temporal and spatial distribution of selected contaminants of emerging concern, water samples were collected throughout 2018 and 2019 at 11 sites within the S. Platte River and surrounding tributaries with varying proximities to a major wastewater treatment plant (WWTP). Water samples were analyzed for pharmaceuticals, pesticides, steroid hormones, and wastewater indicators and screened for in vitro biological activities. Multiplexed, in vitro assays that simultaneously screen for agonistic activity against 24 human nuclear receptors detected estrogen receptor (ER), peroxisome proliferator activated receptor-gamma (PPARγ), and glucocorticoid receptor (GR) bioactivities in water samples near the WWTP outflow. Targeted in vitro bioassays assessing ER, GR, and PPARγ agonism corroborated bioactivities for ER (up to 55 ± 9.7 ng/L 17β-estradiol equivalents) and GR (up to 156 ± 28 ng/L dexamethasone equivalents), while PPARγ activity was not confirmed. To evaluate the potential in vivo significance of the bioactive contaminants, sexually-mature fathead minnows were caged at six locations upstream and downstream of the WWTP for 5 days after which targeted gene expression analyses were performed. Significant up-regulation of male hepatic vitellogenin was observed at sites with corresponding in vitro ER activity. No site-related differences in GR-related transcript abundance were detected in female adipose or male livers, suggesting observed environmental concentrations of GR-active contaminants do not induce a detectable in vivo response. In line with the lack of detectable targeted in vitro PPARɣ activity, there were no significant effects on PPARɣ-related gene expression. Although the chemicals responsible for GR and PPAR-mediated bioactivities are unknown, results from the present study provide insights into the significance (or lack thereof) of these bioactivities relative to short-term in situ fish exposures.

Environmental Pollution↗
USGS2019

Assessment of the potential for in-plume sulphur dioxide gas-ash interactions to influence the respiratory toxicity of volcanic ash

Background Volcanic plumes are complex environments composed of gases and ash particles, where chemical and physical processes occur at different temperature and compositional regimes. Commonly, soluble sulphate- and chloride-bearing salts are formed on ash as gases interact with ash surfaces. Exposure to respirable volcanic ash following an eruption is potentially a significant health concern. The impact of such gas-ash interactions on ash toxicity is wholly un-investigated. Here, we study, for the first time, whether the interaction of volcanic particles with sulphur dioxide (SO 2 ) gas, and the resulting presence of sulphate salt deposits on particle surfaces, influences toxicity to the respiratory system, using an advanced in vitro approach. Methods To emplace surface sulphate salts on particles, via replication of the physicochemical reactions that occur between pristine ash surfaces and volcanic gas, analogue substrates (powdered synthetic volcanic glass and natural pumice) were exposed to SO 2 at 500 °C, in a novel Advanced Gas-Ash Reactor, resulting in salt-laden particles. The solubility of surface salt deposits was then assessed by leaching in water and geochemical modelling. A human multicellular lung model was exposed to aerosolised salt-laden and pristine (salt-free) particles, and incubated for 24 h. Cell cultures were subsequently assessed for biological endpoints, including cytotoxicity (lactate dehydrogenase release), oxidative stress (oxidative stress-related gene expression; heme oxygenase 1 and NAD(P)H dehydrogenase [quinone] 1) and its (pro-)inflammatory response (tumour necrosis factor α, interleukin 8 and interleukin 1β at gene and protein levels). Results In the lung cell model no significant effects were observed between the pristine and SO 2 -exposed particles, indicating that the surface salt deposits, and the underlying alterations to the substrate, do not cause acute adverse effects in vitro . Based on the leachate data, the majority of the sulphate salts from the ash surfaces are likely to dissolve in the lungs prior to cellular uptake. Conclusions The findings of this study indicate that interaction of volcanic ash with SO 2 during ash generation and transport does not significantly affect the respiratory toxicity of volcanic ash in vitro . Therefore, sulphate salts are unlikely a dominant factor controlling variability in in vitro toxicity assessments observed during previous eruption response efforts.

Environmental Research↗
USGS2016

Estimating microcystin levels at recreational sites in western Lake Erie and Ohio

Cyanobacterial harmful algal blooms (cyanoHABs) and associated toxins, such as microcystin, are a major global water-quality issue. Water-resource managers need tools to quickly predict when and where toxin-producing cyanoHABs will occur. This could be done by using site-specific models that estimate the potential for elevated toxin concentrations that cause public health concerns. With this study, samples were collected at three Ohio lakes to identify environmental and water-quality factors to develop linear-regression models to estimate microcystin levels. Measures of the algal community (phycocyanin, cyanobacterial biovolume, and cyanobacterial gene concentrations) and pH were most strongly correlated with microcystin concentrations. Cyanobacterial genes were quantified for general cyanobacteria, general Microcystis and Dolichospermum , and for microcystin synthetase ( mcyE ) for Microcystis , Dolichospermum , and Planktothrix. For phycocyanin, the relations were different between sites and were different between hand-held measurements on-site and nearby continuous monitor measurements for the same site. Continuous measurements of parameters such as phycocyanin, pH, and temperature over multiple days showed the highest correlations to microcystin concentrations. The development of models with high R 2 values (0.81–0.90), sensitivities (92%), and specificities (100%) for estimating microcystin concentrations above or below the Ohio Recreational Public Health Advisory level of 6 μg L −1 was demonstrated for one site; these statistics may change as more data are collected in subsequent years. This study showed that models could be developed for estimates of exceeding a microcystin threshold concentration at a recreational freshwater lake site, with potential to expand their use to provide relevant public health information to water resource managers and the public for both recreational and drinking waters.

Ohio↗
USGS2015

Characterization of the extremely arsenic-resistant Brevibacterium linens strain AE038-8 isolated from contaminated groundwater in Tucumán, Argentina

Brevibacterium linens AE038-8, isolated from As-contaminated groundwater in Tucumán (Argentina), is highly resistant to arsenic oxyanions, being able to tolerate up to 1 M As(V) and 75 mM As(III) in a complex medium. Strain AE038-8 was also able to reduce As(V) to As(III) when grown in complex medium but paradoxically it could not do this in a defined minimal medium with sodium acetate and ammonium sulfate as carbon and nitrogen sources, respectively. No oxidation of As(III) to As(V) was observed under any conditions. Three copies of the ars operon comprising arsenic resistance genes were found on B. linens AE038-8 genome. In addition to the well known arsC , ACR3 and arsR , two copies of the arsO gene of unknown function were detected.

Tucumán↗
USGS2021

Coalescent methods reconstruct contributions of natural colonization and stocking to origins of Michigan inland Cisco (Coregonus artedi)

Fish population structure in previously glaciated regions is often influenced by natural colonization processes and human-mediated dispersal, including fish stocking. Endemic populations are of conservation interest because they may contain rare and unique genetic variation. While coregonines are native to certain Michigan inland lakes, some were stocked with fish from Great Lakes sources, calling into question the origin of extant populations. While most stocking targeted lake whitefish ( Coregonus clupeaformis ), cisco ( C. artedi ) were also stocked from the Great Lakes to inland waterbodies. We used population genetic data (microsatellite genotypes and mitochondrial (mt)DNA sequences), coalescent modeling, and approximate Bayesian computation to investigate the origins of 12 inland Michigan cisco populations. The spatial distribution of mtDNA haplotypes suggests Michigan is an introgression zone for two ancestral cisco lineages associated with separate glacial refugia. Low levels of genetic diversity and high levels of genetic divergence were observed for populations located well inland of the Great Lakes relative to populations occupying waterbodies near the Great Lakes. Estimates of recent Great Lakes gene flow ranged from 27 to 48% for populations near the Great Lakes shoreline but were substantially lower (under 8%) for populations further inland. Inland lakes with elevated recent gene flow estimates may have been recipients of stocked coregonine fry, including cisco. Low levels of genetic diversity paired with a high likelihood of endemism as indicated by strong genetic divergence and low Great Lakes population inputs suggest the analyzed cisco populations occupying southern Michigan kettle lakes are of elevated conservation interest.

Michigan↗
USGS2018

A transcriptome resource for the Arctic Cod (Boreogadus saida)

Arctic Cod ( Boreogadus saida ) serve as an important link in Arctic food webs and are thus considered an important species for environmental monitoring. RNA-Seq was conducted on samples from wild-collected individuals representing various age classes and tissue types to obtain as complete a transcriptome as possible on an Illumina MiSeq, which resulted in a total of 64,457 transcripts with an average length of 295 bp. We identified well-known genes that are associated with temperature change or response to pollutants. This RNA-Seq effort provides the first insight into the B. saida transcriptome, which can be a starting point for investigations identifying genes for local adaptation and genomic responses to future environmental change.

Marine Genomics↗
USGS2014

Avian influenza virus ecology in Iceland shorebirds: intercontinental reassortment and movement

Shorebirds are a primary reservoir of avian influenza viruses (AIV). We conducted surveillance studies in Iceland shorebird populations for 3 years, documenting high serological evidence of AIV exposure in shorebirds, primarily in Ruddy Turnstones ( Arenaria interpres ; seroprevalence = 75%). However, little evidence of virus infection was found in these shorebird populations and only two turnstone AIVs (H2N7; H5N1) were able to be phylogenetically examined. These analyses showed that viruses from Iceland shorebirds were primarily derived from Eurasian lineage viruses, yet the H2 hemagglutinin gene segment was from a North American lineage previously detected in a gull from Iceland the previous year. The H5N1 virus was determined to be low pathogenic, however the PB2 gene was closely related to the PB2 from highly pathogenic H5N1 isolates from China. Multiple lines of evidence suggest that the turnstones were infected with at least one of these AIV while in Iceland and confirm Iceland as an important location where AIV from different continents interact and reassort, creating new virus genomes. Mounting data warrant continued surveillance for AIV in wild birds in the North Atlantic, including Canada, Greenland, and the northeast USA to determine the risks of new AI viruses and their intercontinental movement in this region.

Infection, Genetics and Evolution↗
USGS2016

Detection of hepatitis E virus and other livestock-related pathogens in Iowa streams

Manure application is a source of pathogens to the environment. Through overland runoff and tile drainage, zoonotic pathogens can contaminate surface water and streambed sediment and could affect both wildlife and human health. This study examined the environmental occurrence of gene markers for livestock-related bacterial, protozoan, and viral pathogens and antibiotic resistance in surface waters within the South Fork Iowa River basin before and after periods of swine manure application on agricultural land. Increased concentrations of indicator bacteria after manure application exceeding Iowa's state bacteria water quality standards suggest that swine manure contributes to diminished water quality and may pose a risk to human health. Additionally, the occurrence of HEV and numerous bacterial pathogen genes for Escherichia coli , Enterococcus spp., Salmonella sp., and Staphylococcus aureus in both manure samples and in corresponding surface water following periods of manure application suggests a potential role for swine in the spreading of zoonotic pathogens to the surrounding environment. During this study, several zoonotic pathogens were detected including Shiga-toxin producing E. coli , Campylobacter jejuni , pathogenic enterococci, and S. aureus ; all of which can pose mild to serious health risks to swine, humans, and other wildlife. This research provides the foundational understanding required for future assessment of the risk to environmental health from livestock-related zoonotic pathogen exposures in this region. This information could also be important for maintaining swine herd biosecurity and protecting the health of wildlife near swine facilities.

Iowa↗
USGS2017

Effect of salinity on mercury methylating benthic microbes and their activities in Great Salt Lake, Utah

Surface water and biota from Great Salt Lake (GSL) contain some of the highest documented concentrations of total mercury (THg) and methylmercury (MeHg) in the United States. In order to identify potential biological sources of MeHg and controls on its production in this ecosystem, THg and MeHg concentrations, rates of Hg(II)-methylation and MeHg degradation, and abundances and compositions of archaeal and bacterial 16 rRNA gene transcripts were determined in sediment along a salinity gradient in GSL. Rates of Hg(II)-methylation were inversely correlated with salinity and were at or below the limits of detection in sediment sampled from areas with hypersaline surface water. The highest rates of Hg(II)-methylation were measured in sediment with low porewater salinity, suggesting that benthic microbial communities inhabiting less saline environments are supplying the majority of MeHg in the GSL ecosystem. The abundance of 16S rRNA gene transcripts affiliated with the sulfate reducer Desulfobacterium sp. was positively correlated with MeHg concentrations and Hg(II)-methylation rates in sediment, indicating a potential role for this taxon in Hg(II)-methylation in low salinity areas of GSL. Reactive inorganic Hg(II) (a proxy used for Hg(II) available for methylation) and MeHg concentrations were inversely correlated with salinity. Thus, constraints imposed by salinity on Hg(II)-methylating populations and the availability of Hg(II) for methylation are inferred to result in higher MeHg production potentials in lower salinity environments. Benthic microbial MeHg degradation was also most active in lower salinity environments. Collectively, these results suggest an important role for sediment anoxia and microbial sulfate reducers in the production of MeHg in low salinity GSL sub-habitats and may indicate a role for salinity in constraining Hg(II)-methylation and MeHg degradation activities by influencing the availability of Hg(II) for methylation.

Utah↗
USGS2019

Mixed-chemical exposure and predicted effects potential in wadeable southeastern USA streams

Complex chemical mixtures have been widely reported in larger streams but relatively little work has been done to characterize them and assess their potential effects in headwaterstreams. In 2014, the United States Geological Survey (USGS) sampled 54 Piedmont streams over ten weeks and measured 475 unique organic compounds using five analytical methods. Maximum and median exposure conditions were evaluated in relation to watershed characteristics and for potential biological effects using multiple lines of evidence. Results demonstrate that mixed-contaminant exposures are ubiquitous and varied in sampled headwater streams. Approximately 56% (264) of the 475 compounds were detected at least once across all sites. Cumulative maximum concentrations ranged 1,922–162,346 ng L −1 per site. Chemical occurrence significantly correlated to urban land use but was not related to presence/absence of wastewater treatment facility discharges. Designed bioactive chemicals represent about 2/3rd of chemicals detected, notably pharmaceuticals and pesticides, qualitative evidence for possible adverse biological effects. Comparative Toxicogenomics Database chemical-gene associations applied to maximum exposure conditions indicate >12,000 and 2,900 potential gene targets were predicted at least once across all sites for fish and invertebrates, respectively. Analysis of cumulative exposure-activity ratios provided additional evidence that, at a minimum, transient exposures with high probability of molecular effects to vertebrates were common. Finally, cumulative detections and concentrations correlated inversely with invertebrate metrics from in-stream surveys. The results demonstrate widespread instream exposure to extensive contaminant mixtures and compelling multiple lines of evidence for adverse effects on aquatic communities.

Science of the Total Environment↗
USGS2020

Poultry litter as potential source of pathogens and other contaminants in groundwater and surface water proximal to large-scale confined poultry feeding operations

Manure from livestock production has been associated with the contamination of water resources. To date, research has primarily focused on runoff of these contaminants from animal operations into surface water, and the introduction of poultry-derived pathogenic zoonoses and other contaminants into groundwater is under-investigated. We characterized pathogens and other microbial and chemical contaminants in poultry litter, groundwater, and surface water near confined poultry feeding operations (chicken layer, turkey) at 9 locations in Iowa and one in Wisconsin from May and June 2016. Results indicate that poultry litter from large-scale poultry confined feeding operations is a likely source of environmental contamination and that groundwater is also susceptible to such poultry-derived contamination. Poultry litter, groundwater, and surface water samples had detections of viable bacteria growth (Salmonella spp., enterococci, staphylococci, lactobacilli), multi-drug resistant Salmonella DT104 flost and int genes, F+ RNA coliphage (group I and IV), antibiotic resistance genes (ARGs; blaDHA, blaOXA-48, blaTEM, blaCMY-2, tetM), phytoestrogens (biochanin A, daidzein, formononetin), and a progestin (progesterone). In addition, mcr-1 (a colistin ARG), was detected in a groundwater sample and in another groundwater sample, antibiotic resistant isolates were positive for Brevibacterium spp., a potential signature of poultry in the environment. Detectable estrogenicity was not measured in poultry litter, but was observed in 67% of the surface water samples and 22% were above the U.S. Environmental Protection Agency trigger level of 1 ng/L. The transport of microbial pathogens to groundwater was significantly greater (p < 0.001) than the transport of trace organic contaminants to groundwater in this study. In addition to viable pathogens, several clinically important ARGs were detected in litter, groundwater, and surface water, highlighting the need for additional research on sources of these contaminants in livestock dominated areas.

Iowa, Wisconsin↗
USGS2023

Multi-omics responses in tree swallow (Tachycineta bicolor) nestlings from the Maumee Area of Concern, Maumee River, Ohio

A multi-omics approach was utilized to identify altered biological responses and functions, and to prioritize contaminants to assess the risks of chemical mixtures in the Maumee Area of Concern (AOC), Maumee River, OH, USA. The Maumee AOC is designated by the United States Environmental Protection Agency as having significant beneficial use impairments, including degradation of fish and wildlife populations, bird or animal deformities or reproduction problems, and loss of fish and wildlife habitat. Tree swallow ( Tachycineta bicolor ) nestlings were collected at five sites along the Maumee River, which included wastewater treatment plants (WWTPs) and industrial land-use sites. Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo p dioxins and furans (PCDD/Fs), and chlorinated pesticide concentrations were elevated in Maumee tree swallows, relative to a remote reference site, Star Lake, WI, USA. Liver tissue was utilized for non-targeted transcriptome and targeted metabolome evaluation. A significantly differentially expressed gene cluster related to a downregulation in cell growth and cell cycle regulation was identified when comparing all Maumee River sites with the reference site. There was an upregulation of lipogenesis genes, such as PPAR signaling ( HMGCS2 , SLC22A5 ), biosynthesis of unsaturated fatty acids (FASN, SCD, ELOVL2, and FADS2), and higher lipogenesis related metabolites, such as docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) at two industrial land-use sites, Ironhead and Maumee, relative to WWTP sites (Perrysburg and SideCut), and the reference site. Toledo Water, in the vicinity of the other two industrial sites and also adjacent to a WWTP, showed a mix of signals between industrial land-use and WWTP land-use. PAHs, oxychlordane, and PBDEs were determined to be the most likely causes of the differentiation in biological responses, including de novo lipogenesis and biosynthesis of unsaturated fatty acids.

Ohio↗
USGS2024

Hormetic and transcriptomic responses of the toxic alga Prymnesium parvum to glyphosate

Growth of the toxic alga Prymnesium parvum is hormetically stimulated with environmentally relevant concentrations of glyphosate. The mechanisms of glyphosate hormesis in this species, however, are unknown. We evaluated the transcriptomic response of P. parvum to glyphosate at concentrations that stimulate maximum growth and where growth is not different from control values, the zero-equivalent point (ZEP). Maximum growth occurred at 0.1 mg l −1 and the ZEP was 2 mg l −1 . At 0.1 mg l −1 , upregulated transcripts outnumbered downregulated transcripts by one order of magnitude. Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that the upregulated transcriptome is primarily associated with metabolism and biosynthesis. Transcripts encoding heat shock proteins and co-chaperones were among the most strongly upregulated, and several others were associated with translation, Redox homeostasis, cell replication, and photosynthesis. Although most of the same transcripts were also upregulated at concentrations ≥ZEP, the proportion of downregulated transcripts greatly increased as glyphosate concentrations increased. At the ZEP, downregulated transcripts were associated with photosynthesis, cell replication, and anion transport, indicating that specific interference with these processes is responsible for the nullification of hormetic growth. Transcripts encoding the herbicidal target of glyphosate, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), were upregulated at concentrations ≥ZEP but not at 0.1 mg l −1 , indicating that disruption of EPSPS activity occurred at high concentrations and that nullification of hormetic growth involves the direct interaction of glyphosate with this enzyme. Results of this study may contribute to a better understanding of glyphosate hormesis and of anthropogenic factors that influence P. parvum biogeography and bloom formation.

Science of the Total Environment↗
USGS2025

Soil-microbial communities respond less than plant communities to synthetic- or bio-herbicides applied to address the exotic grass-fire cycle in rangelands

The exotic grass-fire cycle is degrading semiarid rangelands, such as the vast areas of shrub-steppe in North America now invaded by fire-promoting cheatgrass. Chemical- or bio-herbicides are sprayed onto soils to inhibit the invaders, but information on chemical- or bio-herbicide impacts to soil microbial communities is limited. We asked how the soil-microbiome responded to the bioherbicide Pseudomonas fluorescens strain ACK55 in comparison to the separate and combined effects of a conventional pre-emergent chemical herbicide, imazapic, in two cheatgrass-invaded sagebrush-steppe sites. First-year microbial responses were evaluated using targeted sequencing of the 16S and LSU rRNA genes for bacteria+archaea and fungi, respectively, and were related to plant-community responses. A strong cheatgrass reduction with imazapic at one site was accompanied by a small shift in bacteria+archaea (16S) community composition with no effect on microbial alpha diversity, and this shift was small in comparison to natural microbiome variation between sites. ACK55 was not detected in soil a year after application, and it caused only transient and marginally significant reductions in annual grass cover accompanied by small reductions in soil fungi species richness. Full-length sequencing of the ACK55 16S rRNA gene and phylogenetic analyses revealed that ACK55 is more likely P. salmonii than P. fluorescens . Knowledge gaps remain on the duration and consequences of microbial-community shifts with imazapic and why molecular analyses showed ACK55 did not persist in soils. Confusion regarding microbial biopesticides can result where isolation, effectiveness testing, commercial release, and regulation are not guided by molecular taxonomic analyses.

Idaho↗