Polystyrene micro- and nanoplastics cause placental dysfunction in mice†.

Maternal exposure to microplastics and nanoplastics has been shown to result in fetal growth restriction in mice. In this study, we investigated the placental and fetal hemodynamic responses to plastics exposure in mice using high-frequency ultrasound. Healthy, pregnant CD-1 dams were given either 106 ng/L of 5 µm polystyrene microplastics or 106 ng/L of 50 nm polystyrene nanoplastics in drinking water throughout gestation and were compared with controls. Maternal exposure to both microplastics and nanoplastics resulted in evidence of placental dysfunction that was highly dependent on the particle size. The umbilical artery blood flow increased by 48% in the microplastic-exposed group and decreased by 25% in the nanoplastic-exposed group compared to controls (p < 0.05). The microplastic- and nanoplastic-exposed fetuses showed a significant decrease in the middle cerebral artery pulsatility index of 10% and 13%, respectively, compared to controls (p < 0.05), indicating vasodilation of the cerebral circulation, a fetal adaptation that is part of the brain sparing response to preserve oxygen delivery. Hemodynamic markers of placental dysfunction and fetal hypoxia were more pronounced in the group exposed to polystyrene nanoplastics, suggesting nanoplastic exposure during human pregnancy has the potential to disrupt fetal brain development, which in turn may cause suboptimal neurodevelopmental outcomes.

Metabolomics revealed disruptions in amino acid and antioxidant biochemistry in Daphnia magna exposed to industrial effluents associated with plastic and polymer production.

Industrial wastewater effluents are a major source of chemicals in aquatic environments, and many of these chemicals may negatively impact aquatic life. In this study, the crustacean Daphnia magna, a common model organism in ecotoxicity studies, was exposed for 48 h to nine different industrial effluent samples from manufacturing facilities associated with the production of plastics, polymers, and coating products at a range of dilutions: 10, 25, 50, 100% (undiluted). A targeted metabolomic-based approach using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify polar metabolites from individual daphnids that survived the 48 h exposure. Multivariate analyses and metabolite changes revealed metabolic perturbations across all effluent samples studied, with non-monotonic responses and both up and downregulation relative to the unexposed control. Pathway analyses indicated the disruption of similar and distinct pathways, mostly connected to protein synthesis, amino acid metabolism, and antioxidant processes. Overall, we observed disruptions in Daphnia biochemistry that were similar across the effluent samples, but with unique features for each effluent sample. Additionally, non-monotonic heightened responses suggested additive and/or synergistic interactions between the chemicals within the industrial effluents. These findings demonstrate that targeted metabolomic approaches are a powerful tool for the biomonitoring of aquatic ecosystems in the context of complex mixtures, such as industrial wastewater effluents.

Brewing alcohol 101: An undergraduate experiment utilizing benchtop NMR for quantification and process monitoring.

In recent years there has been a renewed interest in benchtop NMR. Given their lower cost of ownership, smaller footprint, and ease of use, they are especially suited as an educational tool. Here, a new experiment targeted at upper-year undergraduates and first-year graduate students follows the conversion of D-glucose into ethanol at low-field. First, high and low-field data on D-glucose are compared and students learn both the Hz and ppm scales and how J-coupling is field-independent. The students then acquire their own quantitative NMR datasets and perform the quantification using an Electronic Reference To Access In Vivo Concentration (ERETIC) technique. To our knowledge ERETIC is not currently taught at the undergraduate level, but has an advantage in that internal standards are not required; ideal for following processes or with future use in flow-based benchtop monitoring. Using this quantitative data, students can relate a simple chemical process (fermentation) back to more complex topics such as reaction kinetics, bridging the gaps between analytical and physical chemistry. When asked to reflect on the experiment, students had an overwhelmingly positive experience, citing agreement with learning objectives, ease of understanding the protocol, and enjoyment. Each of the respondents recommended this experiment as a learning tool for others. This experiment has been outlined for other instructors to utilize in their own courses across institutions, with the hope that a continued expansion of low-field NMR will increase accessibility and learning opportunities at the undergraduate level.

Low-field, not low quality: 1D simplification, selective detection, and heteronuclear 2D experiments for improving low-field NMR spectroscopy of environmental and biological samples.

Understanding environmental change is challenging and requires molecular-level tools to explain the physicochemical phenomena behind complex processes. Nuclear magnetic resonance (NMR) spectroscopy is a key tool that provides information on both molecular structures and interactions but is underutilized in environmental research because standard "high-field" NMR is financially and physically inaccessible for many and can be overwhelming to those outside of disciplines that routinely use NMR. "Low-field" NMR is an accessible alternative but has reduced sensitivity and increased spectral overlap, which is especially problematic for natural, heterogeneous samples. Therefore, the goal of this study is to investigate and apply innovative experiments that could minimize these challenges and improve low-field NMR analysis of environmental and biological samples. Spectral simplification (JRES, PSYCHE, singlet-only, multiple quantum filters), selective detection (GEMSTONE, DREAMTIME), and heteronuclear (reverse and CH3/CH2/CH-only HSQCs) NMR experiments are tested on samples of increasing complexity (amino acids, spruce resin, and intact water fleas) at-high field (500 MHz) and at low-field (80 MHz). A novel experiment called Doubly Selective HSQC is also introduced, wherein 1H signals are selectively detected based on the 1H and 13C chemical shifts of 1H-13C J-coupled pairs. The most promising approaches identified are the selective techniques (namely for monitoring), and the reverse and CH3-only HSQCs. Findings ultimately demonstrate that low-field NMR holds great potential for biological and environmental research. The multitude of NMR experiments available makes NMR tailorable to nearly any research need, and low-field NMR is therefore anticipated to become a valuable and widely used analytical tool moving forward.

Slice through the water-Exploring the fundamental challenge of water suppression for benchtop NMR systems.

Benchtop NMR provides improved accessibility in terms of cost, space, and technical expertise. In turn, this encourages new users into the field of NMR spectroscopy. Unfortunately, many interesting samples in education and research, from beer to whole blood, contain significant amounts of water that require suppression in 1H NMR in order to recover sample information. However, due to the significant reduction in chemical shift dispersion in benchtop NMR systems, the sample signals are much closer to the water resonance compared to those in a corresponding high-field NMR spectrum. Therefore, simply translating solvent suppression experiments intended for high-field NMR instruments to benchtop NMR systems without careful consideration can be problematic. In this study, the effectiveness of several popular water suppression schemes was evaluated for benchtop NMR applications. Emphasis is placed on pulse sequences with no, or few, adjustable parameters making them easy to implement. These fall into two main categories: (1) those based on Pre-SAT including Pre-SAT, PURGE, NOESY-PR, and g-NOESY-PR and (2) those based on binomial inversion including JRS and W5-WATERGATE. Among these schemes, solvent suppression sequences based on Pre-SAT offer a general approach for easy solvent suppression for samples with higher analyte concentrations (sucrose standard and Redbull™). However, for human urine, binomial-like sequences were required. In summary, it is demonstrated that highly efficient water suppression approaches can be implemented on benchtop NMR systems in a simple manner, despite the limited spectral dispersion, further illustrating the potential for widespread implementation of these approaches in education and research.

HR-MAS DREAMTIME NMR for Slow Spinning ex Vivo and in Vivo Samples.

HR-MAS NMR is a powerful tool, capable of monitoring molecular changes in intact heterogeneous samples. However, one of the biggest limitations of 1H NMR is its narrow spectral width which leads to considerable overlap in complex natural samples. DREAMTIME NMR is a highly selective technique that allows users to isolate suites of metabolites from congested spectra. This permits targeted metabolomics by NMR and is ideal for monitoring specific processes. To date, DREAMTIME has only been employed in solution-state NMR, here it is adapted for HR-MAS applications. At high spinning speeds (>5 kHz), DREAMTIME works with minimal modifications. However, spinning over 3-4 kHz leads to cell lysis, and if maintaining sample integrity is necessary, slower spinning (<2.5 kHz) is required. Very slow spinning (≤500 Hz) is advantageous for in vivo analysis to increase organism survival; however, sidebands from water pose a problem. To address this, a version of DREAMTIME, termed DREAMTIME-SLOWMAS, is introduced. Both techniques are compared at 2500, 500, and 50 Hz, using ex vivo worm tissue. Following this, DREAMTIME-SLOWMAS is applied to monitor key metabolites of anoxic stress in living shrimp at 500 Hz. Thus, standard DREAMTIME works well under MAS conditions and is recommended for samples reswollen in D2O or spun >2500 Hz. For slow spinning in vivo or intact tissue samples, DREAMTIME-SLOWMAS provides an excellent way to target process-specific metabolites while maintaining sample integrity. Overall, DREAMTIME should find widespread application wherever targeted molecular information is required from complex samples with a high degree of spectral overlap.

Maternal exposure to polystyrene nanoplastics alters fetal brain metabolism in mice.

INTRODUCTION: Plastics used in everyday materials accumulate as waste in the environment and degrade over time. The impacts of the resulting particulate micro- and nanoplastics on human health remain largely unknown. In pregnant mice, we recently demonstrated that exposure to nanoplastics throughout gestation and during lactation resulted in changes in brain structure detected on MRI. One possible explanation for this abnormal postnatal brain development is altered fetal brain metabolism. OBJECTIVES: To determine the effect of maternal exposure to nanoplastics on fetal brain metabolism. METHODS: Healthy pregnant CD-1 mice were exposed to 50 nm polystyrene nanoplastics at a concentration of 106 ng/L through drinking water during gestation. Fetal brain samples were collected at embryonic day 17.5 (n = 18-21 per group per sex) and snap-frozen in liquid nitrogen. Magic angle spinning nuclear magnetic resonance was used to determine metabolite profiles and their relative concentrations in the fetal brain. RESULTS: The relative concentrations of gamma-aminobutyric acid (GABA), creatine and glucose were found to decrease by 40%, 21% and 30% respectively following maternal nanoplastic exposure when compared to the controls (p < 0.05). The change in relative concentration of asparagine with nanoplastic exposure was dependent on fetal sex (p < 0.005). CONCLUSION: Maternal exposure to polystyrene nanoplastics caused abnormal fetal brain metabolism in mice. The present study demonstrates the potential impacts of nanoplastic exposure during fetal development and motivates further studies to evaluate the risk to human pregnancies.

Soil organic matter molecular composition with long-term detrital alterations is controlled by site-specific forest properties.

Forest ecosystems are important global soil carbon (C) reservoirs, but their capacity to sequester C is susceptible to climate change factors that alter the quantity and quality of C inputs. To better understand forest soil C responses to altered C inputs, we integrated three molecular composition published data sets of soil organic matter (SOM) and soil microbial communities for mineral soils after 20 years of detrital input and removal treatments in two deciduous forests: Bousson Forest (BF), Harvard Forest (HF), and a coniferous forest: H.J. Andrews Forest (HJA). Soil C turnover times were estimated from radiocarbon measurements and compared with the molecular-level data (based on nuclear magnetic resonance and specific analysis of plant- and microbial-derived compounds) to better understand how ecosystem properties control soil C biogeochemistry and dynamics. Doubled aboveground litter additions did not increase soil C for any of the forests studied likely due to long-term soil priming. The degree of SOM decomposition was higher for bacteria-dominated sites with higher nitrogen (N) availability while lower for the N-poor coniferous forest. Litter exclusions significantly decreased soil C, increased SOM decomposition state, and led to the adaptation of the microbial communities to changes in available substrates. Finally, although aboveground litter determined soil C dynamics and its molecular composition in the coniferous forest (HJA), belowground litter appeared to be more influential in broadleaf deciduous forests (BH and HF). This synthesis demonstrates that inherent ecosystem properties regulate how soil C dynamics change with litter manipulations at the molecular-level. Across the forests studied, 20 years of litter additions did not enhance soil C content, whereas litter reductions negatively impacted soil C concentrations. These results indicate that soil C biogeochemistry at these temperate forests is highly sensitive to changes in litter deposition, which are a product of environmental change drivers.

Exploring Proton-Only NMR Experiments and Filters for Daphnia In Vivo: Potential and Limitations.

Environmental metabolomics provides insight into how anthropogenic activities have an impact on the health of an organism at the molecular level. Within this field, in vivo NMR stands out as a powerful tool for monitoring real-time changes in an organism's metabolome. Typically, these studies use 2D 13C-1H experiments on 13C-enriched organisms. Daphnia are the most studied species, given their widespread use in toxicity testing. However, with COVID-19 and other geopolitical factors, the cost of isotope enrichment increased ~6-7 fold over the last two years, making 13C-enriched cultures difficult to maintain. Thus, it is essential to revisit proton-only in vivo NMR and ask, "Can any metabolic information be obtained from Daphnia using proton-only experiments?". Two samples are considered here: living and whole reswollen organisms. A range of filters are tested, including relaxation, lipid suppression, multiple-quantum, J-coupling suppression, 2D 1H-1H experiments, selective experiments, and those exploiting intermolecular single-quantum coherence. While most filters improve the ex vivo spectra, only the most complex filters succeed in vivo. If non-enriched organisms must be used, then, DREAMTIME is recommended for targeted monitoring, while IP-iSQC was the only experiment that allowed non-targeted metabolite identification in vivo. This paper is critically important as it documents not just the experiments that succeed in vivo but also those that fail and demonstrates first-hand the difficulties associated with proton-only in vivo NMR.

SASSY NMR: Simultaneous Solid and Solution Spectroscopy.

Synergism between different phases gives rise to chemical, biological or environmental reactivity, thus it is increasingly important to study samples intact. Here, SASSY (SimultAneous Solid and Solution spectroscopY) is introduced to simultaneously observe (and differentiate) all phases in multiphase samples using standard, solid-state NMR equipment. When monitoring processes, the traditional approach of studying solids and liquids sequentially, can lead to information in the non-observed phase being missed. SASSY solves this by observing the full range of materials, from crystalline solids, through gels, to pure liquids, at full sensitivity in every scan. Results are identical to running separate 13 C CP-MAS solid-state and 13 C solution-state experiments back-to-back but requires only a fraction of the spectrometer time. After its introduction, SASSY is applied to process monitoring and finally to detect all phases in a living freshwater shrimp. SASSY is simple to implement and thus should find application across all areas of research.

Gas Chromatography-(Cyclic) Ion Mobility Mass Spectrometry: A Novel Platform for the Discovery of Unknown Per-/Polyfluoroalkyl Substances.

Per- and polyfluoroalkyl substances (PFASs) have been widely used since the 1940s in industry and everyday household products. They also persist in the environment and bioaccumulate in humans and wildlife. Despite these concerns, the identities of most PFASs in environmental and biological samples are unknown. Herein, we describe a novel cyclic ion mobility mass spectrometer (cIMS), hyphenated with gas chromatography (GC) atmospheric pressure chemical ionization, that can reveal the presence of unknown PFASs on the basis of the ratio of their mass and collision cross section (CCS). Prediction of the CCS of ca. 20,000 chemicals used in industry and commerce indicates that most compounds characterized by CCS values that are less than the sum of 100 Å2 and one-fifth of their mass are either PFASs or polybrominated flame retardants. When this filter is applied to GC-cIMS data collected from a set of 20 indoor dust samples, PFAS compounds are revealed without prior knowledge of their occurrence. Validation of this approach was performed using SRM 2585, a standard reference material of household dust, by comparing the PFASs detected with those (tentatively) identified in previous studies. Chlorofluoro phthalimides tentatively identified previously were confirmed with a synthesized standard. The method also reveals the presence of chlorofluoro n-alkanes as an emerging class of "forever chemicals" that contaminate the indoor environment.

Exploring the Applications of Carbon-Detected NMR in Living and Dead Organisms Using a 13C-Optimized Comprehensive Multiphase NMR Probe.

Comprehensive multiphase-nuclear magnetic resonance (CMP-NMR) is a non-invasive approach designed to observe all phases (solutions, gels, and solids) in intact samples using a single NMR probe. Studies of dead and living organisms are important to understand processes ranging from biological growth to environmental stress. Historically, such studies have utilized 1H-based phase editing for the detection of soluble/swollen components and 1H-detected 2D NMR for metabolite assignments/screening. However, living organisms require slow spinning rates (∼500 Hz) to increase survivability, but at such low speeds, complications from water sidebands and spectral overlap from the modest chemical shift window (∼0-10 ppm) make 1H NMR challenging. Here, a novel 13C-optimized E-Free magic angle spinning CMP probe is applied to study all phases in ex vivo and in vivo samples. This probe consists of a two-coil design, with an inner single-tuned 13C coil providing a 113% increase in 13C sensitivity relative to a traditional multichannel single-CMP coil design. For organisms with a large biomass (∼0.1 g) like the Ganges River sprat (ex vivo), 13C-detected full spectral editing and 13C-detected heteronuclear correlation (HETCOR) can be performed at natural abundance. Unfortunately, for a single living shrimp (∼2 mg), 13C enrichment was still required, but 13C-detected HETCOR shows superior data relative to heteronuclear single-quantum coherence at low spinning speeds (due to complications from water sidebands in the latter). The probe is equipped with automatic-tuning-matching and is compatible with automated gradient shimming─a key step toward conducting multiphase screening of dead and living organisms under automation in the near future.

Placental metabolite profiles in late gestation for healthy mice.

INTRODUCTION: During pregnancy, appropriate placental metabolism is essential for fetuses to reach their growth potential. However, metabolic mechanisms during pregnancy remain poorly understood. Determination of the levels of placental metabolites in healthy pregnancy and how they change throughout gestation is critical for understanding placental function. OBJECTIVE: To determine the effects of gestational age on placental metabolites using healthy pregnant mice. METHODS: In the present study, we collected placental tissue samples from healthy pregnant mice at three timepoints in late gestation (n = 16 placentas per gestational age). Metabolite profiles were determined using 1H high-resolution magic angle spinning magnetic resonance spectroscopy (HRMAS MRS). RESULTS: Using HRMAS MRS, we identified 14 metabolites in murine placental tissue samples. The relative concentration of 12 of the 14 metabolites remains unchanged throughout late gestation. Lysine was found to decrease significantly (p = 0.04) and glucose showed an inverted U-shape relationship (p = 0.03) with gestational age. CONCLUSION: This study demonstrated the feasibility of HRMAS MRS to determine relative metabolite concentrations in murine placental tissue. These findings establish baseline levels of placental tissue metabolite profiles and will serve as reference ranges for future studies using mouse models of fetal distress.

Maternal exposure to polystyrene microplastics alters placental metabolism in mice.

INTRODUCTION: The rapid growth in the worldwide use of plastics has resulted in a vast accumulation of microplastics in the air, soil and water. The impact of these microplastics on pregnancy and fetal development remains largely unknown. In pregnant mice, we recently demonstrated that exposure to micro- and nanoplastics throughout gestation resulted in significant fetal growth restriction. One possible explanation for reduced fetal growth is abnormal placental metabolism. OBJECTIVES: To evaluate the effect of maternal exposure to microplastics on placental metabolism. METHODS: In the present study, CD-1 pregnant mice were exposed to 5 µm polystyrene microplastics in filtered drinking water at one of four concentrations (0 ng/L (controls), 102 ng/L, 104 ng/L, 106 ng/L) throughout gestation (n = 7-11/group). At embryonic day 17.5, placental tissue samples were collected (n = 28-44/group). Metabolite profiles were determined using 1 H high-resolution magic angle spinning magnetic resonance spectroscopy. RESULTS: The relative concentration of lysine (p = 0.003) and glucose (p < 0.0001) in the placenta were found to decrease with increasing microplastic concentrations, with a significant reduction at the highest exposure concentration. Multivariate analysis identified shifts in the metabolic profile with MP exposure and pathway analysis identified perturbations in the biotin metabolism, lysine degradation, and glycolysis/gluconeogenesis pathways. CONCLUSION: Maternal exposure to microplastics resulted in significant alterations in placental metabolism. This study highlights the potential impact of microplastic exposure on pregnancy outcomes and that efforts should be made to minimize exposure to plastics, particularly during pregnancy.

Comparison of sub-lethal metabolic perturbations of select legacy and novel perfluorinated alkyl substances (PFAS) in Daphnia magna.

Per- and polyfluoroalkyl substances (PFAS) are a class of pollutants of concern due to their ubiquitous presence, persistence, and toxicity in aquatic environments. Legacy PFAS pollutants such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been more widely studied in aquatic environments. However, replacement PFAS, such as ammonium perfluoro (2-methyl-3-oxahexanoate; GenX) are increasingly being detected with little known information surrounding their toxicity. Here, Daphnia magna, a model organism for freshwater ecotoxicology was used to compare the acute sub-lethal toxicity of PFOS, PFOA, GenX, and PFAS mixtures. Using liquid chromatography with tandem mass spectrometry (LC-MS/MS), the targeted polar metabolic profile extracted from single Daphnia was quantified to investigate perturbations in the exposure groups versus the unexposed organisms. Multivariate statistical analyses demonstrated significant non-monotonic separation in PFOA, GenX, and PFAS mixture exposures. Sub-lethal exposure to concentrations of PFOS did not lead to significant separation in multivariate analyses. Univariate statistics and pathway analyses were used to elucidate the mode of action of PFAS exposure. Exposure to all individual PFAS led to significant perturbations in many amino acids including cysteine, histidine, tryptophan, glycine, and serine. These perturbations are consistent with biochemical pathway disruptions in the pantothenate and Coenzyme A (CoA) biosynthesis, thiamine metabolism, histidine metabolism, and aminoacyl-tRNA biosynthesis pathways. Overall, the collected metabolomic data is consistent with disruptions in energy metabolism and protein synthesis as the primary mode of action of sub-lethal PFAS exposure. Secondary modes of action among individual pollutant exposures demonstrated that the structural properties (carboxylic acid vs. sulfonic acid group) may play a role in the metabolic perturbations observed. Sub-lethal exposure to PFAS mixtures highlighted a mixed response when compared to the individual pollutants (PFOS, PFOA, and GenX). Overall, this study emphasizes the niche capability of environmental metabolomics to differentiate secondary modes of action from metabolic perturbations in both single pollutant and pollutant mixtures within the same chemical class.

Data-Independent Identification of Suspected Organic Pollutants Using Gas Chromatography-Atmospheric Pressure Chemical Ionization-Mass Spectrometry.

The identity of an unknown environmental pollutant is reflected by the mass and dissociation chemistry of its (quasi)molecular ion. Gas chromatography-atmospheric pressure chemical ionization-mass spectrometry (GC-APCI-MS) increases the yield of molecular ions (compared to conventional electron ionization) by collisional cooling. Scanning quadrupole data-independent acquisition (SQDIA) permits unbiased, unattended selection of (quasi)molecular ions and acquisition of structure-diagnostic collision-induced dissociation mass spectra, while minimizing interferences, by sequentially cycling a quadrupole isolation window through the m/z range. This study reports on the development of a suspect screening method based on industrial compounds with bioaccumulation potential. A comparison of false and correct identifications in a mixed standard containing 30 analytes suggests that SQDIA results in a markedly lower false-positive rate than standard DIA: 5 for SQDIA and 82 for DIA. Electronic waste dust was analyzed using GC and quadrupole time-of-flight MS with APCI and SQDIA acquisition. A total of 52 brominated, chlorinated, and organophosphorus compounds were identified by suspect screening; 15 unique elemental compositions were identified using nontargeted screening; 17 compounds were confirmed using standards and others identified to confidence levels 2, 3, or 4. SQDIA reduced false-positive identifications, compared to experiments without quadrupole isolation. False positives also varied by class: 20% for Br, 37% for Cl, 75% for P, and >99% for all other classes. The structure proposal of a previously reported halogenated compound was revisited. The results underline the utility of GC-SQDIA experiments that provide information on both the (quasi)molecular ions and its dissociation products for a more confident structural assignment.

Comprehensive Multiphase NMR Probehead with Reduced Radiofrequency Heating Improves the Analysis of Living Organisms and Heat-Sensitive Samples.

Comprehensive multiphase (CMP) NMR, first described in 2012, combines all of the hardware components necessary to analyze all phases (solid, gel, and solution) in samples in their natural state. In combination with spectral editing experiments, it can fully differentiate phases and study the transfer of chemical species across and between phases, providing unprecedented molecular-level information in unaltered natural systems. However, many natural samples, such as swollen soils, plants, and small organisms, contain water, salts, and ionic compounds, making them electrically lossy and susceptible to RF heating, especially when using high-strength RF fields required to select the solid domains. While dedicated reduced-heating probes have been developed for solid-state NMR, to date, all CMP-NMR probes have been based on solenoid designs, which can lead to problematic sample heating. Here, a new prototype CMP probe was developed, incorporating a loop gap resonator (LGR) for decoupling. Temperature increases are monitored in salt solutions analogous to those in small aquatic organisms and then tested in vivo on Hyalella azteca (freshwater shrimp). In the standard CMP probe (solenoid), 80% of organisms died within 4 h under high-power decoupling, while in the LGR design, all organisms survived the entire test period of 12 h. The LGR design reduced heating by a factor of ∼3, which allowed 100 kHz decoupling to be applied to salty samples with generally ≤10 °C sample heating. In addition to expanding the potential for in vivo research, the ability to apply uncompromised high-power decoupling could be beneficial for multiphase samples containing true crystalline solids that require the strongest possible decoupling fields for optimal detection.

Expanding current applications and permitting the analysis of larger intact samples by means of a 7 mm CMP-NMR probe.

Comprehensive multiphase NMR combines the ability to study and differentiate all phases (solids, gels, and liquids) using a single NMR probe. The general goal of CMP-NMR is to study intact environmental and biological samples to better understand conformation, organization, association, and transfer between and across phases/interfaces that may be lost with conventional sample preparation such as drying or solubilization. To date, all CMP-NMR studies have used 4 mm probes and rotors. Here, a larger 7 mm probehead is introduced which provides ∼3 times the volume and ∼2.4 times the signal over a 4 mm version. This offers two main advantages: (1) the additional biomass reduces experiment time, making 13C detection at natural abundance more feasible; (2) it allows the analysis of larger samples that cannot fit within a 4 mm rotor. Chicken heart tissue and Hyalella azteca (freshwater shrimp) are used to demonstrate that phase-based spectral editing works with 7 mm rotors and that the additional biomass from the larger volumes allows detection with 13C at natural abundance. Additionally, a whole pomegranate seed berry (aril) and an intact softgel capsule of hydroxyzine hydrochloride are used to demonstrate the analysis of samples too large to fit inside a conventional 4 mm CMP probe. The 7 mm version introduced here extends the range of applications and sample types that can be studied and is recommended when 4 mm CMP probes cannot provide adequate signal-to-noise (S/N), or intact samples are simply too big for 4 mm rotors.

Endocrine Disruptor Exposure Causes Infochemical Dysregulation and an Ecological Cascade from Zooplankton to Algae.

Endocrine disruption is intimately linked to controlling the population of pollutant-exposed organisms through reproduction and development dysregulation. This study investigated how endocrine disruption in a predator organism could affect prey species biology through infochemical communication. Daphnia magna and Chlorella vulgaris were chosen as model prey and predator planktons, respectively, and fenoxycarb was used for disrupting the endocrine system of D. magna. Hormones as well as endo- and exometabolomes were extracted from daphnids and algal cells and their culture media and analyzed using liquid chromatography with tandem mass spectrometry. Biomolecular perturbations of D. magna under impaired offspring production and hormone dysregulation were observed. Differential biomolecular responses of the prey C. vulgaris, indicating changes in methylation and infochemical communication, were subsequently observed under the exposure to predator culture media, containing infochemicals released from the reproducibly normal and abnormal D. magna, as results of fenoxycarb exposure. The observed cross-species transfer of the endocrine disruption consequences, initiated from D. magna, and mediated through infochemical communication, demonstrates a novel discovery and emphasizes the broader ecological risk of endocrine disruptors beyond reproduction disruption in target organisms.

Which of the (Mixed) Halogenated n-Alkanes Are Likely To Be Persistent Organic Pollutants?

Short-chain polychlorinated n-alkanes are ubiquitous industrial chemicals widely recognized as persistent organic pollutants. They represent only a small fraction of the 184,600 elemental compositions (C10-25) and the myriad isomers of all possible (mixed) halogenated n-alkanes (PXAs). This study prioritizes the PXAs on the basis of their potential to persist, bioaccumulate, and undergo long-range transport guided by quantitative structure-property relationships (QSPRs), density functional theory (DFT), chemical fate models, and partitioning space. The QSPR results narrow the list to 966 elemental compositions, of which 352 (23 Br, 83 Cl/F, 119 Br/Cl, and 127 Br/F) are likely constituents of substances used as lubricants, plasticizers, and flame retardants. Complementary DFT calculations suggest that an additional 1367 elemental compositions characterized by a greater number of carbon and fluorine atoms but fewer chlorine and bromine atoms may also pose a risk. The results of this study underline the urgent need to identify and monitor these suspected pollutants, most appropriately using mass spectrometry. We estimate that the resolving power required to distinguish ∼74% of the prioritized elemental compositions from the most likely interferents, i.e., chlorinated alkanes, is approximately 60,000 (full width at half-maximum). This indicates that accurate identification of the PXAs is achievable using most high-resolution mass spectrometers.