Timing of antibiotic administration determines the spread of plasmid-encoded antibiotic resistance during microbial range expansion.

Plasmids are the main vector by which antibiotic resistance is transferred between bacterial cells within surface-associated communities. In this study, we ask whether there is an optimal time to administer antibiotics to minimize plasmid spread in new bacterial genotypes during community expansion across surfaces. We address this question using consortia of Pseudomonas stutzeri strains, where one is an antibiotic resistance-encoding plasmid donor and the other a potential recipient.

Machine Learning-Based Hazard-Driven Prioritization of Features in Nontarget Screening of Environmental High-Resolution Mass Spectrometry Data.

Nontarget high-resolution mass spectrometry screening (NTS HRMS/MS) can detect thousands of organic substances in environmental samples. However, new strategies are needed to focus time-intensive identification efforts on features with the highest potential to cause adverse effects instead of the most abundant ones. To address this challenge, we developed MLinvitroTox, a machine learning framework that uses molecular fingerprints derived from fragmentation spectra (MS2) for a rapid classification of thousands of unidentified HRMS/MS features as toxic/nontoxic based on nearly 400 target-specific and over 100 cytotoxic endpoints from ToxCast/Tox21.

Methods comparison for detecting trends in herbicide monitoring time-series in streams.

An inadvertent consequence of pesticide use is aquatic pesticide pollution, which has prompted the implementation of mitigation measures in many countries. Water quality monitoring programs are an important tool to evaluate the efficacy of these mitigation measures. However, large interannual variability of pesticide losses makes it challenging to detect significant improvements in water quality and to attribute these improvements to the application of specific mitigation measures.

Importance of artificial high flows in maintaining the ecological integrity of a regulated river.

Artificial high flows attempt to simulate natural flood pulses in flow-regulated rivers with the intent to improve their ecological integrity. The long-term use of such high flow events have shown beneficial ecological effects on various rivers globally. However, such responses are often non-linear and characterized by underlying feedback mechanisms among ecosystem components.

A legacy of invasive sun corals: Distinct mobile invertebrate assemblages at near-reef coral-dominated rubble.

Fast-growing and reproducing sun corals have successfully invaded rocky reefs around the Atlantic Ocean, markedly reducing the diversity of fouling invertebrates and macroalgae, and profoundly changing the composition of reef-associated mobile invertebrates. Here, we address sun-coral rubble depositions and report, for the first time, the effects of sun corals on near-reef soft-bottom invertebrate assemblages. Abundance, richness and diversity were higher at rubble habitats compared to bare sandy grounds, which could be a positive effect of substrate complexity.

Modernizing persistence-bioaccumulation-toxicity (PBT) assessment with high throughput animal-free methods.

The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union's chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment.

Importance of Dietary Uptake for in Situ Bioaccumulation of Systemic Fungicides Using Gammarus pulex as a Model Organism.

Bioaccumulation of organic contaminants from contaminated food sources might pose an underestimated risk toward shredding invertebrates. This assumption is substantiated by monitoring studies observing discrepancies of predicted tissue concentrations determined from laboratory-based experiments compared with measured concentrations of systemic pesticides in gammarids. To elucidate the role of dietary uptake in bioaccumulation, gammarids were exposed to leaf material from trees treated with a systemic fungicide mixture (azoxystrobin, cyprodinil, fluopyram, and tebuconazole), simulating leaves entering surface waters in autumn.

Microbial assessment of water, sanitation, and hygiene (WaSH) in temporary and permanent settlements two years after Nepal 2015 earthquake.

Disaster-induced displacement often causes people to live in temporary settlements that have limited infrastructure and access to water, sanitation, and hygiene (WaSH). Reducing the risk of diarrheal diseases in such situations requires knowing how housing influences the presence of pathogens in water and the interaction between human settlements and exposure to pathogens. A cross-sectional study was conducted in May 2017 in two communities hard-hit by the Nepal 2015 earthquake: one recovered with newly reconstructed houses, and one recovered with residents still living in sheet metal temporary shelters constructed after the earthquake.

Conserved Molecular Players Involved in Human Nose Morphogenesis Underlie Evolution of the Exaggerated Snout Phenotype in Cichlids.

Instances of repeated evolution of novel phenotypes can shed light on the conserved molecular mechanisms underlying morphological diversity. A rare example of an exaggerated soft tissue phenotype is the formation of a snout flap in fishes. This tissue flap develops from the upper lip and has evolved in one cichlid genus from Lake Malawi and one genus from Lake Tanganyika.

Monitoring contaminants of emerging concern in aquatic systems through the lens of citizen science.

Global urbanization trends have led to the widespread increasing occurrence of contaminants of emerging concern (CECs) such as pharmaceuticals, personal care products, pesticides, and micro- and nano-plastics in aquatic systems. Even at low concentrations, these contaminants pose a threat to aquatic ecosystems. To better understand the effects of CECs on aquatic ecosystems, it is important to measure concentrations of these contaminants present in these systems.

Ozonation of lake water and wastewater: Identification of carbonous and nitrogenous carbonyl-containing oxidation byproducts by non-target screening.

Ozonation of drinking water and wastewater is accompanied by the formation of disinfection byproducts (DBPs) such as low molecular weight aldehydes and ketones from the reactions of ozone with dissolved organic matter (DOM). By applying a recently developed non-target workflow, 178 carbonous and nitrogenous carbonyl compounds were detected during bench-scale ozonation of two lake waters and three secondary wastewater effluent samples and full-scale ozonation of secondary treated wastewater effluent. An overlapping subset of carbonyl compounds (20%) was detected in all water types.

Long-term preservation of biomolecules in lake sediments: potential importance of physical shielding by recalcitrant cell walls.

Even though lake sediments are globally important organic carbon (OC) sinks, the controls on long-term OC storage in these sediments are unclear. Using a multiproxy approach, we investigate changes in diatom, green algae, and vascular plant biomolecules in sedimentary records from the past centuries across five temperate lakes with different trophic histories. Despite past increases in the input and burial of OC in sediments of eutrophic lakes, biomolecule quantities in sediments of all lakes are primarily controlled by postburial microbial degradation over the time scales studied.

Deposit-feeding worms control subsurface ecosystem functioning in intertidal sediment with strong physical forcing.

Intertidal sands are global hotspots of terrestrial and marine carbon cycling with strong hydrodynamic forcing by waves and tides and high macrofaunal activity. Yet, the relative importance of hydrodynamics and macrofauna in controlling these ecosystems remains unclear. Here, we compare geochemical gradients and bacterial, archaeal, and eukaryotic gene sequences in intertidal sands dominated by subsurface deposit-feeding worms () to adjacent worm-free areas.

Microbial population dynamics decouple growth response from environmental nutrient concentration.

How the growth rate of a microbial population responds to the environmental availability of chemical nutrients and other resources is a fundamental question in microbiology. Models of this response, such as the widely used Monod model, are generally characterized by a maximum growth rate and a half-saturation concentration of the resource. What values should we expect for these half-saturation concentrations, and how should they depend on the environmental concentration of the resource? We survey growth response data across a wide range of organisms and resources.

Genomic basis of Y-linked dwarfism in cichlids pursuing alternative reproductive tactics.

Sexually antagonistic selection, which favours different optima in males and females, is predicted to play an important role in the evolution of sex chromosomes. Body size is a sexually antagonistic trait in the shell-brooding cichlid fish Lamprologous callipterus, as "bourgeois" males must be large enough to carry empty snail shells to build nests whereas females must be small enough to fit into shells for breeding. In this species, there is also a second male morph: smaller "dwarf" males employ an alternative reproductive strategy by wriggling past spawning females into shells to fertilize eggs.

Putative metabolism of Ca. Accumulibacter via the utilization of glucose.

Ca. Accumulibacter was the predominant microorganism (relative FISH bio-abundance of 67 ± 5%) in a lab-scale sequential batch reactor that accomplished enhanced biological phosphorus removal (EBPR) while using glucose and acetate as the carbon sources (1:1 COD-based ratio). Both organic compounds were completely anaerobically consumed.

Fungal hyphae regulate bacterial diversity and plasmid-mediated functional novelty during range expansion.

The amount of bacterial diversity present on many surfaces is enormous; however, how these levels of diversity persist in the face of the purifying processes that occur as bacterial communities expand across space (referred to here as range expansion) remains enigmatic. We shed light on this apparent paradox by providing mechanistic evidence for a strong role of fungal hyphae-mediated dispersal on regulating bacterial diversity during range expansion. Using pairs of fluorescently labeled bacterial strains and a hyphae-forming fungal strain that expand together across a nutrient-amended surface, we show that a hyphal network increases the spatial intermixing and extent of range expansion of the bacterial strains.

Speed it up: How temperature drives toxicokinetics of organic contaminants in freshwater amphipods.

The acceleration of global climate change draws increasing attention towards interactive effects of temperature and organic contaminants. Many studies reported a higher sensitivity of aquatic invertebrates towards contaminant exposure with increasing or fluctuating temperatures. The hypothesis of this study was that the higher sensitivity of invertebrates is associated with the changes of toxicokinetic processes that determine internal concentrations of contaminants and consequently toxic effects.

Seasonal drivers and risks of aquatic pesticide pollution in drought and post-drought conditions in three Mediterranean watersheds.

The Western Cape in South Africa has a Mediterranean climate, which has in part led to an abundance of agriculturally productive land supporting the wheat, deciduous fruit, wine, and citrus industries. South Africa is the leading pesticide user in Sub-Saharan Africa. There is limited data on the pesticide pollution of surface water over different seasons in low- and middle-income countries.

Genome-wide base editor screen identifies regulators of protein abundance in yeast.

Proteins are key molecular players in a cell, and their abundance is extensively regulated not just at the level of gene expression but also post-transcriptionally. Here, we describe a genetic screen in yeast that enables systematic characterization of how protein abundance regulation is encoded in the genome. The screen combines a CRISPR/Cas9 base editor to introduce point mutations with fluorescent tagging of endogenous proteins to facilitate a flow-cytometric readout.

Pesticide exposure and cortical brain activation among farmworkers in Costa Rica.

Background: Previous epidemiological studies have reported associations of pesticide exposure with poor cognitive function and behavioral problems. However, these findings have relied primarily on neuropsychological assessments. Questions remain about the neurobiological effects of pesticide exposure, specifically where in the brain pesticides exert their effects and whether compensatory mechanisms in the brain may have masked pesticide-related associations in studies that relied purely on neuropsychological measures.

Biodegradation of poly(butylene succinate) in soil laboratory incubations assessed by stable carbon isotope labelling.

Using biodegradable instead of conventional plastics in agricultural applications promises to help overcome plastic pollution of agricultural soils. However, analytical limitations impede our understanding of plastic biodegradation in soils. Utilizing stable carbon isotope (C-)labelled poly(butylene succinate) (PBS), a synthetic polyester, we herein present an analytical approach to continuously quantify PBS mineralization to CO during soil incubations and, thereafter, to determine non-mineralized PBS-derived C remaining in the soil.

Ecology and evolution of competitive trait variation in natural phytoplankton communities under selection.

Competition for limited resources is a major force in structuring ecological communities. Species minimum resource requirements (R*s) can predict competitive outcomes and evolve under selection in simple communities under controlled conditions. However, whether R*s predict competitive outcomes or demonstrate adaptive evolution in naturally complex communities is unknown.

Rearing performance of black soldier fly () on municipal biowaste in the outdoor ambient weather conditions of Pakistan and Indonesia.

The availability and continuous supply of black soldier fly larvae (BSFL) is crucial for efficient operation of a BSF biowaste recycling facility. Its rearing performance was for the first time investigated in Pakistan under outdoor ambient weather conditions. Comparison of the findings with the BSF rearing performance of Indonesia's facility highlights the life stages needing special attention.