Crystallographic and chemical signatures in coral skeletal aragonite

Corals nucleate and grow aragonite crystals, organizing them into intricate skeletal structures that ultimately build the world’s coral reefs. Crystallography and chemistry have profound influence on the material properties of these skeletal building blocks, yet gaps remain in our knowledge about coral aragonite on the atomic scale. Across a broad diversity of shallow-water and deep-sea scleractinian corals from vastly different environments, coral aragonites are remarkably similar to one another, confirming that corals exert control on the carbonate chemistry of the calcifying space relative to the surrounding seawater. Nuances in coral aragonite structures relate most closely to trace element chemistry and aragonite saturation state, suggesting the primary controls on aragonite structure are ionic strength and trace element chemistry, with growth rate playing a secondary role. We also show how coral aragonites are crystallographically indistinguishable from synthetic abiogenic aragonite analogs precipitated from seawater under conditions mimicking coral calcifying fluid. In contrast, coral aragonites are distinct from geologically formed aragonites, a synthetic aragonite precipitated from a freshwater solution, and mollusk aragonites. Crystallographic signatures have future applications in understanding the material properties of coral aragonite and predicting the persistence of coral reefs in a rapidly changing ocean.

Application of Single-Particle Mass Spectrometer to Obtain Chemical Signatures of Various Combustion Aerosols

A single-particle mass spectrometer (SPMS) with laser ionization was constructed to determine the chemical composition of single particles in real time. The technique was evaluated using various polystyrene latex particles with different sizes (125 nm, 300 nm, 700 nm, and 1000 nm); NaCl, KCl, MgCO3, CaCO3, and Al2O3 particles with different chemical compositions; an internal mixture of NaCl and KCl; and an internal mixture of NaCl, KCl, and MgCl2 with different mixing states. The results show that the SPMS can be useful for the determination of chemical characteristics and mixing states of single particles in real time. The SPMS was then applied to obtain the chemical signatures of various combustion aerosols (diesel engine exhaust, biomass burning (rice straw), coal burning, and cooking (pork)) based on their single-particle mass spectra. Elemental carbon (EC)-rich and EC-organic carbon (OC) particles were the predominant particle types identified in diesel engine exhaust, while K-rich and EC-OC-K particles were observed among rice straw burning emissions. Only one particle type (ash-rich particles) was detected among coal burning emissions. EC-rich and EC-OC particles were observed among pork burning particles. The single-particle mass spectra of the EC or OC types of particles differed among various combustion sources. The observed chemical signatures could be useful for rapidly identifying sources of atmospheric fine particles. In addition, the detected chemical signatures of the fine particles may be used to estimate their toxicity and to better understand their effects on human health.

Experimental induction of resins as a tool to understand variability in ambers

Amber is chiefly known as a preservational medium of biological inclusions, but it is itself a chemofossil, comprised of fossilised plant resin. The chemistry of today's resins has been long investigated as a means of understanding the botanical sources of ambers. However, little is known about the chemical variability of resins and consequently about that of the ambers that are derived from particular resins. We undertook experimental resin production in Araucariacean plants to clarify how much natural resin variability is present in two species, Agathis australis and Wollemia nobilis, and whether different resin exudation stimuli types can be chemically identified and differentiated. The latter were tested on the plants, and the resin exudates were collected and investigated with Fourier-transform infrared attenuated total reflection (FTIR-ATR) spectroscopy to give an overview of their chemistry for comparisons, including multivariate analyses. The Araucariacean resins tested did not show distinct chemical signatures linked to a particular resin-inducing treatment. Nonetheless, we did detect two separate groupings of the treatments for Agathis, in which the branch removal treatment and mimicked insect-boring treatment-derived resin spectra were more different from the resin spectra derived from other treatments. This appears linked to the lower resin viscosities observed in the branch- and insect-treatment-derived resins. However the resins, no matter the treatment, could be distinguished from both species. The effect of genetic variation was also considered using the same stimuli on both the seed-grown A. australis derived from wild-collected populations and on clonally derived W. nobilis plants with natural minimal genetic diversity. The variability in the resin chemistries collected did reflect the genetic variability of the source plant. We suggest that this natural variability needs to be taken into account when testing resin and amber chemistries in the future.

Analysis of melanotic Plasmodium spp. capsules in mosquitoes reveal eumelanin-pheomelanin composition and identify AgMesh as a modulator of parasite infection

Melanins are structurally complex pigments produced by organisms in all domains of life from bacteria to animals, including humans. In insects, melanins are essential for survival and have key roles in cuticle sclerotization, wound healing and innate immunity. In this study, we used a diverse set of molecular, biochemical, and imaging approaches to characterize mosquito melanin involved in innate immune defense (melanotic capsules ). We observed that melanotic capsules enclosing Plasmodium berghei ookinetes were composed of an acid-resistant and highly hydrophobic material with granular appearance, which are characteristic properties of melanins. Spectroscopical analyses reveal chemical signatures of eumelanins and pheomelanin. Furthermore, using an enrichment approach for the proteomic analysis, we identified a set of 14 of acid-resistant mosquito proteins embedded within the melanin matrix possibly related to an anti- Plasmodium response. Among these, Ag Mesh, a highly conserved protein among insect species that contains domains suggesting a role in immune recognition and function. We targeted Ag Mesh for further study using a RNAi-based gene silencing approach in mosquitos and challenged them with two Plasmodium spp. Surprisingly, Ag Mesh gene silencing in mosquitos was associated with reduced parasite infection, implying an important role in facilitating vector infection by Plasmodium spp. Our results provide a new approach to study aspects of insect melanogenesis that revealed proteins associated with melanotic capsule, one of which was strongly implicated in the pathogenesis of Plasmodium spp. mosquito infection. Given the conservation of Ag Mesh among disease-transmitting insect vector species, future analysis of this protein could provide fertile ground for the identification of strategies that block transmission of disease to humans.

Traffic, Drugs, Mental Health, and Disinfectants: Changes in Sewage Sludge Chemical Signatures During a COVID-19 Community Lockdown

<p>The COVID-19 pandemic and related shutdowns have caused changes in everyday activities for many people, and signs of those changes are present in the chemical signatures of sewage sludge produced during the pandemic. We analyzed primary sewage sludge samples from a wastewater treatment plant in New Haven, CT USA collected between March 19 and June 30, 2020. This time period encompassed the first wave of the COVID-19 pandemic, the initial statewide stay at home order, and the first phase of reopening. We used liquid chromatography coupled with high resolution mass spectrometry and targeted and suspect screening strategies to identify contaminants in the sludge. We and found evidence of increasing opioid, cocaine, and antidepressant use, as well as upward trends in chemicals used in disinfectants and sunscreens during the study period. Benzotriazole, an anti-corrosion chemical associated with traffic pollution, decreased through the stay-at-home period, and increased during reopening. Hydroxychloroquine, a drug that received significant attention for its potential to treat COVID-19, had elevated concentrations in the week following the implementation of the United States Emergency Use Authorization. Our results directly relate to nationwide reports of increased demand for fentanyl, antidepressants, and other medications, as well as reports of increased drug overdose deaths during the pandemic. Though wastewater surveillance during the pandemic has largely focused on measuring SARS-CoV-2 RNA concentrations, chemical analysis can also show trends that are important for revealing the public and environmental health effects of the pandemic. </p>