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Consortia of multicellular magnetotactic bacteria (MMB) are currently the only known example of bacteria without a unicellular stage in their life cycle. Because of their recalcitrance to cultivation, most previous studies of MMB have been limited to microscopic observations. To study the biology of these unique organisms in more detail, we use multiple culture-independent approaches to analyze the genomics and physiology of MMB consortia at single-cell resolution. We separately sequenced the metagenomes of 22 individual MMB consortia, representing 8 new species, and quantified the genetic diversity within each MMB consortium. This revealed that, counter to conventional views, cells within MMB consortia are not clonal. Single consortia metagenomes were then used to reconstruct the species-specific metabolic potential and infer the physiological capabilities of MMB. To validate genomic predictions, we performed stable isotope probing (SIP) experiments and interrogated MMB consortia using fluorescence in situ hybridization (FISH) combined with nanoscale secondary ion mass spectrometry (NanoSIMS). By coupling FISH with bioorthogonal noncanonical amino acid tagging (BONCAT), we explored their in situ activity as well as variation of protein synthesis within cells. We demonstrate that MMB consortia are mixotrophic sulfate reducers and that they exhibit metabolic differentiation between individual cells, suggesting that MMB consortia are more complex than previously thought. These findings expand our understanding of MMB diversity, ecology, genomics, and physiology, as well as offer insights into the mechanisms underpinning the multicellular nature of their unique lifestyle.

In nanomedicine, determining the spatial distribution of particles and drugs, together and apart, at high resolution within tissues, remains a major challenge because each must have a different label or detectable feature that can be observed with high sensitivity and resolution. We prepared nanoparticles capable of enzyme-directed assembly of particle therapeutics (EDAPT), containing an analogue of the Pt(II)-containing drug oxaliplatin, an 15N-labeled monomer in the hydrophobic block of the backbone of the polymer, the near-infrared dye Cy5.5, and a peptide that is a substrate for tumor metalloproteinases in the hydrophilic block. When these particles reach an environment rich in tumor associated proteases, the hydrophilic peptide substrate is cleaved, causing the particles to accumulate through a morphology transition, locking them in the tumor extracellular matrix. To evaluate the distribution of drug and EDAPT carrier in vivo, the localization of the isotopically labeled polymer backbone was compared to that of Pt by nanoscale secondary ion mass spectrometry (NanoSIMS). The correlation of NanoSIMS with super-resolution fluorescence microscopy revealed the release of the drug from the nanocarrier and colocalization with cellular DNA within tumor tissue. The results confirmed the dependence of particle accumulation and Pt(II) drug delivery on the presence of a Matrix Metalloproteinase (MMP) substrate and demonstrated antitumor activity. We conclude that these techniques are powerful for the elucidation of the localization of cargo and carrier, and enable a high-resolution assessment of their performance following in vivo delivery.

In the Amazon basin, particles containing mixed sodium salts are routinely observed and are attributed to marine aerosols transported from the Atlantic Ocean. Using chemical imaging analysis, we show that, during the wet season, fungal spores emitted by the forest biosphere contribute at least 30% (by number) to sodium salt particles in the central Amazon basin. Hydration experiments indicate that sodium content in fungal spores governs their growth factors. Modeling results suggest that fungal spores account for ~69% (31-95%) of the total sodium mass during the wet season and that their fractional contribution increases during nighttime. Contrary to common assumptions that sodium-containing aerosols originate primarily from marine sources, our results suggest that locally-emitted fungal spores contribute substantially to the number and mass of coarse particles containing sodium. Hence, their role in cloud formation and contribution to salt cycles and the terrestrial ecosystem in the Amazon basin warrant further consideration.

The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orbulina universa, which forms a spherical terminal shell, is paced by the diurnal light/dark cycle. Whether Mg-heterogeneity is also diurnally paced in species with more complex shell morphologies is unknown. Here we show that high Mg/Ca-calcite forms at night in cultured specimens of the multi-chambered species Neogloboquadrina dutertrei. Our results demonstrate that N. dutertrei adds a significant amount of calcite, and nearly all Mg-bands, after the final chamber forms. These results have implications for interpreting patterns of calcification in N. dutertrei and suggest that diurnal Mg-banding is an intrinsic component of biomineralization in planktic foraminifera.

Understanding biomineralization relies on imaging chemically heterogeneous organic–inorganic interfaces across a hierarchy of spatial scales. Further, organic minority phases are often responsible for emergent inorganic structures from the atomic arrangement of different polymorphs, to nano- and micrometer crystal dimensions, up to meter size mollusk shells. The desired simultaneous chemical and elemental imaging to identify sparse organic moieties across a large field-of-view with nanometer spatial resolution has not yet been achieved. Here, we combine nanoscale secondary ion mass spectroscopy (NanoSIMS) with spectroscopic IR s-SNOM imaging for simultaneous chemical, molecular, and elemental nanoimaging. At the example of Pinctada margaritifera mollusk shells we identify and resolve ~ 50 nm interlamellar protein sheets periodically arranged in regular ~ 600 nm intervals. The striations typically appear ~ 15 µm from the nacre-prism boundary at the interface between disordered neonacre to mature nacre. Using the polymorph distinctive IR-vibrational carbonate resonance, the nacre and prismatic regions are consistently identified as aragonite ( ν ¯ a = 860 cm−1) and calcite ( ν ¯ c = 880 cm−1), respectively. We observe previously unreported morphological features including aragonite subdomains encapsulated in extensions of the prism-covering organic membrane and regions of irregular nacre tablet formation coincident with dispersed organics. We also identify a ~ 200 nm region in the incipient nacre region with less well-defined crystal structure and integrated organics. These results show with the identification of the interlamellar protein layer how correlative nano-IR chemical and NanoSIMS elemental imaging can help distinguish different models proposed for shell growth in particular, and how organic function may relate to inorganic structure in other biomineralized systems in general. [ABSTRACT FROM AUTHOR]

Oxygen isotopes are a valuable tool for determining the role of supracrustal rocks in the genesis of magmas and help constrain the source regions of plutonism in the northern Appalachian mountains of North America. Zircons from 35 igneous or metaigneous rocks mainly from southern New England, USA, were analyzed for [sup.18]O/[sup.16]O to locate and investigate the origin of anomalous [δ.sup.18]O magmas and to evaluate the regional meteoric water-rock interaction. [δ.sup.18]O values of the zircons obtained using the laser fluorination technique vary between 2.3 [per thousand] and 11.0‰, relative to Vienna Standard Mean Ocean Water (VSMOW). Zircons from two plutons in the Avalon terrane reveal the presence of anomalously low- [δ.sup.18]O ( Les isotopes de l'oxygene sontun outil important pour determiner le role des roches supracrustales dans lagenese des magmas et ils aident a delimiter les regions sources du plutonisme dans le nord des montagnes appalachiennes de l'Amerique du Nord. Des zircons provenant de 35 roches ignees ou meta-ignees, principalement du sud de la NouvelleAngleterre, ont ete analyses pour [sup.18]O/[sup.16]O afin de localiser et d'etudier l'origine des magmas a anomalie [δ.sup.18]O et d'evaluer les interactions regionales entre l'eau meteorique et les roches. Les valeurs [δ.sup.18]O des zircons, obtenues au moyen de la technique de fluoration au laser, varient entre 2,3 ‰ et 11,0 ‰ VSMOW (eau oceanique moyenne normalisee de Vienne). Les zircons provenant de deux plutons du terrane d'Avalon revelent la presence de zircons a teneur [δ.sup.18]O anormalement basse (> (Ordovicien tardif a Silurien precoce) du nord du Connecticut (zircon [δ.sup.18]O en vrac = 7,56 ‰) indiquent l'incorporation de quantites importantes de composantes sedimentaires a teneur elevee [δ.sup.18]Oa partir des regions sources plus anciennes dans ces magmas. Les terranes d'Avalon et de Gander du sud-est de la Nouvelle-Angleterre et la bordure est de Laurentia ont subi de longs historiques d'enfouissement ou de subduction, de fusion et d'assimilation de roches provenant de la surface au cours du Neoproterozoique et du milieu du Paleozoique. [Traduit par lar Redaction], Introduction Compared with other rock-forming minerals such as quartz and feldspar, zircon is highly resistant to oxygen isotopic exchange during post-crystallization hydrothermal alteration (e.g., Valley 2003) and thus can be [...]

Zircons from 71 diverse rocks from the Qinling-Tongbai-Dabie-Sulu orogenic belt in east-central China and, for comparison, eight from adjoining areas in the South China and North China blocks, have been analyzed for in situ [sup.18]O/[sup.16]O ratio and/or U-Pb age to further constrain the spatial distribution and genesis of Neoproterozoic low-δ[sup.18]O magmas, that is, δ[sup.18]O(zircon) ≤ 4 [per thousand] VSMOW. In many metaigneous rock samples from Tongbai-Dabie-Sulu, including high-pressure and ultrahigh-pressure eclogites and associated granitic orthogneisses, average δ[sup.18]O values for Neoproterozoic 'igneous' zircon cores (i.e., 800-600 Ma) vary from -0.9 to 6.9[per thousand], and from -9.9 to 6.8 ‰ for Triassic metamorphic rims (i.e., 245-200 Ma). The former extend to values lower than zircons in primitive magmas from the Earth's mantle (ca. 5-6 ‰). The average Δ[sup.18]O (metamorphic zircon--'igneous' zircon) values vary from -11.6 to 0.9‰. The large volume of Neoproterozoic low-δ[sup.18]O igneous protoliths at Tongbai-Dabie-Sulu is matched only by the felsic volcanic rocks of the Snake River Plain hotspot track, which terminates at the Yellowstone Plateau. Hence, the low-δ[sup.18]O values at Tongbai-Dabie-Sulu are proposed to result from shallow subcaldera processes by comparison with Yellowstone, where repeated caldera-forming magmatism and hydrothermal alteration created similar low-δ[sup.18]O magmas. However, the possibility of involvement of meltwaters from local continental glaciations, rather than global Neoproterozoic glaciations, cannot be precluded. Our data indicate that Neoproterozoic low-δ[sup.18]O magmas that are either subduction- or rift-related are present locally along the western margin of the South China Block (e.g., Baoxing Complex). It appears that Neoproterozoic [sup.18]O-depletion events in the South China Block as the result of hydrothermal alteration and magmatism affected a much larger area than was previously recognized. Keywords Zircon * Oxygen isotopes * Ultrahigh-pressure metamorphism * Qinling-Tongbai-Dabie-Sulu orogenic belt * South China Block, Introduction Zircon may preserve pristine igneous structures and compositions even in highly metamorphosed or hydrothermally altered rocks including oscillatory zoning as revealed by scanning electron microscopy--cathodoluminescence (SEM-CL) imaging, magmatic ages, [...]