Supplement from Export of ice nucleating particles from watersheds: results from the Amazon and Tocantins River Plumes

Numerical data shown in Figure 2 of the manuscript

N and O Isotope Fractionation in Nitrate during Chemolithoautotrophic Denitrification by <i>Sulfurimonas gotlandica</i>

Chemolithoautotrophic denitrification is an important mechanism of nitrogen loss in the water column of euxinic basins, but its isotope fractionation factor is not known. <i>Sulfurimonas gotlandica</i> GD1^T, a recently isolated bacterial key player in Baltic Sea pelagic redoxcline processes, was used to determine the isotope fractionation of nitrogen and oxygen in nitrate during denitrification. Under anoxic conditions, nitrate reduction was accompanied by nitrogen and oxygen isotope fractionation of 23.8 ± 2.5‰ and 11.7 ± 1.1‰, respectively. The isotope effect for nitrogen was in the range determined for heterotrophic denitrification, with only the absence of stirring resulting in a significant decrease of the fractionation factor. The relative increase in δ¹⁸O_NO3 to δ¹⁵N_NO3 did not follow the 1:1 relationship characteristic of heterotrophic, marine denitrification. Instead, δ¹⁸O_NO3 increased slower than δ¹⁵N_NO3, with a conserved ratio of 0.5:1. This result suggests that the periplasmic nitrate reductase (Nap) of <i>S. gotlandica</i> strain GD1^T fractionates the N and O in nitrate differently than the membrane-bound nitrate reductase (Nar), which is generally prevalent among heterotrophic denitrifiers and is considered as the dominant driver for the observed isotope fractionation. Hence in the Baltic Sea redoxcline, other, as yet-unidentified factors likely explain the low apparent fractionation

Detection of enteric colonization with third-generation cephalosporin-resistant Enterobacteriaceae in returned soldiers and previously reported detection rates in selected African and Asian countries (in alphabetic order).

<p>Detection of enteric colonization with third-generation cephalosporin-resistant Enterobacteriaceae in returned soldiers and previously reported detection rates in selected African and Asian countries (in alphabetic order).</p

Detection of third-generation cephalosporin-resistant Enterobacteriaceae per year and yearly percentage of respective detections.

<p>Detection of third-generation cephalosporin-resistant Enterobacteriaceae per year and yearly percentage of respective detections.</p

Detection of third-generation cephalosporin-resistant Enterobacteriaceae in returning soldiers.

<p>Detection of third-generation cephalosporin-resistant Enterobacteriaceae in returning soldiers.</p

Comparison of trypanosome survival times in cerebrospinal-fluid and/or HMI-9 medium.

<p>AnTat1.1 was isolated 11 days <i>p.i.</i> from rat blood, separated from blood cells and adjusted to a cell density of 5*10⁴ parasites in 100 µl of the respective solution. Contamination of csf with blood did not exceed 20%, as judged from the erythrocyte count. <i>Rattus norvegicus</i> csf supported survival of the parasites only for some 30 hours (▴) and could not be prolonged by supplementing 33 mM glucose (data not shown). However, in a mixture of csf and HMI-9 medium (1∶1), trypanosomes survived significantly longer (i.e. approx. 45 h, ▪). As HMI-9 medium (<b>♦</b>) contains all nutrients in excess, it supports growth of trypanosomes for approximately 56 h, even if diluted with saline solution (1∶1, X).</p

Changes of trypanosomal morphology during the course of infection.

<p><b>a,</b> Scanning electron micrographs of typical stumpy, intermediate and slender form trypanosomes. The size of the pictured trypanosome is 17 µm, 22 µm and 26 µm, respectively. <b>b,</b> Blood samples of 3 infected rats were analyzed for trypanosome titer up to 20 days (♦ [cells/ml]), shown is a representative curve. Additionally, the overall length of the parasites (n = 27) was measured and grouped into stumpy forms (up to 17 µm), intermediate forms (17–23 µm) and slender forms (longer than 23 µm). Intermediate forms (▪ [%]) represent proliferating trypanosomes. Slender forms (▴ [%]) increase continuously at low level during the course of infection and reach up to 40% after 20 days <i>p.i</i>. Distribution of stumpy forms is not explicitly shown but can be calculated as the difference to 100%. <b>c,</b> Comparison of trypanosomes isolated from blood or brain of infected rats. AnTat1.1 has been isolated from rat blood (4 days <i>p.i.</i>, red bars) and rat brain (35 days <i>p.i.</i>, blue bars). The overall length of parasites (n = 96) was measured from the back of the trypanosome to the tip of the flagellum (see inset). We here show that the brain isolate contains a significant amount of trypanosomes longer than 23 µm.</p

Simultaneous ¹⁵N Online Analysis in NH₄⁺, NO₂^–, NO₃^–, and N₂O to Trace N₂O Production Pathways in Nitrogen-Polluted Aqueous Environments

Engineered nitrogen (N) removal processes in water treatment plants and N-transformation reactions in polluted environments represent prominent sources of the potent greenhouse gas, nitrous oxide (N2O). The relevance of microbial and abiotic formation pathways can be assessed by using 15N tracer techniques. While 15N–N2O analysis with optical analyzers is straightforward, the quantification of atom % 15N of inorganic N compounds, such as ammonium (NH4+), nitrite (NO2–), and nitrate (NO3–), requires discrete sample analyses that are time-consuming and labor-intensive. In this study, we developed an automated sample preparation unit, coupled to a membrane inlet quadrupole mass spectrometer, for the online, quasi-simultaneous analysis of atom % 15N in NH4+, NO2–, and NO3–. This technique was designed and validated for 15N-spiking applications at moderate (100–200 μmol L–1, 1 atom % 15N) to high (2–3 mmol L–1, 33 atom % 15N) dissolved inorganic N concentrations typically encountered in sewer systems or contaminated watersheds. The high potential of the developed system, in combination with 15N–N2O analysis by Fourier-transform infrared spectroscopy, to constrain N transformations and sources of N2O was demonstrated in a feasibility study, where nitrifier denitrification was identified as the primary N2O formation pathway during the partial NH4+ oxidation to NO2– in a lab-scale sequencing batch reactor

Electron micrographs showing the location of trypanosomes more than 20 days after blood infection.

<p><b>a,</b> Trypanosomes (T) are in close proximity to pial cells (PC) within the subarachnoid space (SAS); BP brain parenchyma. <b>b,</b> Trypanosomes (T) are located intimately between pial cells (PC) at the intersection between subarachnoid space and <i>pia mater</i>. <b>c,</b> Area of the <i>pia mater</i> containing densly packed trypanosomes between pial cells. A, astroglial endfeet forming the <i>glia limitans</i>; SAS, subarachnoid space. <b>d,</b> Detail of c. Astrocytes (A) forming the <i>glia limitans</i> (lower line of vertical arrows). The upper line of vertical arrows marks the mesothelium. The horizontal arrow labels a tight junction between two pial cells. Trypanosomes (T) are seen between pial cells. <b>e, </b><i>Glia limitans</i> (labelled by two arrows) marks the border between brain parenchyma (BP) and <i>pia mater</i> (PM); A, foot of an astrocyte. In this image trypanosomes (T) are located within the dilated <i>glial limitans</i> (asterisks). <b>f,</b> A trypanosome located between pial cells (PC). The two arrows point to the two flagella proving that the parasites are capable of cell division at this location.</p

Simultaneous ¹⁵N Online Analysis in NH₄⁺, NO₂^–, NO₃^–, and N₂O to Trace N₂O Production Pathways in Nitrogen-Polluted Aqueous Environments

Engineered nitrogen (N) removal processes in water treatment plants and N-transformation reactions in polluted environments represent prominent sources of the potent greenhouse gas, nitrous oxide (N2O). The relevance of microbial and abiotic formation pathways can be assessed by using 15N tracer techniques. While 15N–N2O analysis with optical analyzers is straightforward, the quantification of atom % 15N of inorganic N compounds, such as ammonium (NH4+), nitrite (NO2–), and nitrate (NO3–), requires discrete sample analyses that are time-consuming and labor-intensive. In this study, we developed an automated sample preparation unit, coupled to a membrane inlet quadrupole mass spectrometer, for the online, quasi-simultaneous analysis of atom % 15N in NH4+, NO2–, and NO3–. This technique was designed and validated for 15N-spiking applications at moderate (100–200 μmol L–1, 1 atom % 15N) to high (2–3 mmol L–1, 33 atom % 15N) dissolved inorganic N concentrations typically encountered in sewer systems or contaminated watersheds. The high potential of the developed system, in combination with 15N–N2O analysis by Fourier-transform infrared spectroscopy, to constrain N transformations and sources of N2O was demonstrated in a feasibility study, where nitrifier denitrification was identified as the primary N2O formation pathway during the partial NH4+ oxidation to NO2– in a lab-scale sequencing batch reactor