Fungal Ferromanganese Mineralisation in Cretaceous Dinosaur Bones from the Gobi Desert, Mongolia

Chemical Gardens Mimic Electron Paramagnetic Resonance Spectra and Morphology of Biogenic Mn Oxides

Manganese (Mn) oxides are ubiquitous in nature and occur as both biological and abiotic minerals, but empirically distinguishing between the two remains a problem. Recently, electron paramagnetic resonance (EPR) spectroscopy has been proposed for this purpose. It has been reported that biogenic Mn oxides display a characteristic narrow linewidth in contrast to their pure abiotic counterparts, which is explained in part by the large number of cation vacancies that form within the layers of biogenic Mn oxides. It was, therefore, proposed that natural samples that display a narrow EPR linewidth, ΔHpp < 580G, could be assigned to a biogenic origin. However, in poorly crystalline or amorphous solids, both dipolar broadening and exchange narrowing simultaneously determine the linewidth. Considering that the spectral linewidth is governed by several mechanisms, this approach might be questioned. In this study, we report synthetic chemical garden Mn oxide biomorphs that exhibit both morphologically life-like structures and narrow EPR linewidths, suggesting that a narrow EPR line may be unsuitable as reliable evidence in assessment of biogenicity.

In situ SEM/EDS compositional characterization of osteocytes and blood vessels in fossil and extant turtles on untreated bone surfaces; different preservational pathways microns away

Osteocytes and blood vessels are the main cellular and tissue components of the bone tissue of vertebrates. Evidence of these soft-tissue microstructures has been widely documented in the fossil record of Mesozoic and Cenozoic turtles. However, all these studies have characterized morphologically and elementally these microstructures via isolation from the fossilized bone matrix where they were preserved or in ground sections, which could raise skepticism about the results due to potential cross-contamination or reagents effects. Fossil turtle bones from three different localities with distinct preservation environments and geological settings, including Mongolemys elegans from the Late Cretaceous of Mongolia, Allaeochelys crassesculpta from the Eocene of Germany, and a podocnemidid indet. from the Miocene of Colombia are studied here. Bone from two extant turtle species, Lepidochelys olivacea, and Podocnemis lewyana, as well as a commercial chicken Gallus gallus were used for comparisons. Scanning Electron Microscopy-Energy Dispersive Spectroscopy analyses performed directly on untreated fresh surfaces show that osteocytes-like in the fossil turtle bone are mostly composed of iron and manganese. In contrast, the in situ blood vessels-like of the fossil turtles, as well as those from the extant taxa are rich in elements typically organic in origin (carbon and nitrogen), which are absent to minimally present in the surrounding bone or rock matrix; this suggests a possible endogenous composition for these fossil structures. Also, the results presented here show that although originally both (osteocytes and blood vessels) are organic soft components of bone as evidenced in the extant turtles and chicken, they can experience completely different preservational pathways only microns away from each other in the same fossil bone.

Portraying manganese biofilms via a merger of EPR spectroscopy and cathodic polarization

Microbial biofilms on stainless steel surfaces exposed to water from a freshwater pond were dominated by manganese-oxidizing bacteria, as initially diagnosed by microscopy and elemental analysis. The application of electron paramagnetic resonance (EPR) spectroscopy revealed conspicuous sextet (six-line) patterns that intensified with immersion time, implying the gradual accumulation of Mn(II) in the biofilms. Correspondingly, cathodic polarization designated the manganese oxide (MnO_x) reduction peak in the form of a distinctive 'nose', which grew increasingly more negative with biofilm growth. The progressive expansion of cathodic current densities and the concurrent area-under-the-curve also allowed the quantification of microbially mediated MnO_x deposition_. Furthermore, the merger of EPR and cathodic polarization techniques yielded key insights, in tandem with Mn speciation data, into the pathways of microbial manganese transformations in biofilms, besides providing meaningful interpretations of prevailing literature. Accordingly, the natural freshwater biofilm was inferred as one supporting a complete manganese cycle encompassing multiple redox states.

Yeast-Derived β-Glucan in Cancer: Novel Uses of a Traditional Therapeutic

An increased understanding of the complex mechanisms at play within the tumor microenvironment (TME) has emphasized the need for the development of strategies that target immune cells within the TME. Therapeutics that render the TME immune-reactive have a vast potential for establishing effective cancer interventions. One such intervention is β-glucan, a natural compound with immune-stimulatory and immunomodulatory potential that has long been considered an important anti-cancer therapeutic. β-glucan has the ability to modulate the TME both by bridging the innate and adaptive arms of the immune system and by modulating the phenotype of immune-suppressive cells to be immune-stimulatory. New roles for β-glucan in cancer therapy are also emerging through an evolving understanding that β-glucan is involved in a concept called trained immunity, where innate cells take on memory phenotypes. Additionally, the hollow structure of particulate β-glucan has recently been harnessed to utilize particulate β-glucan as a delivery vesicle. These new concepts, along with the emerging success of combinatorial approaches to cancer treatment involving β-glucan, suggest that β-glucan may play an essential role in future strategies to prevent and inhibit tumor growth. This review emphasizes the various characteristics of β-glucan, with an emphasis on fungal β-glucan, and highlights novel approaches of β-glucan in cancer therapy.

Cretaceous dinosaur bone contains recent organic material and provides an environment conducive to microbial communities

Fossils were thought to lack original organic molecules, but chemical analyses show that some can survive. Dinosaur bone has been proposed to preserve collagen, osteocytes, and blood vessels. However, proteins and labile lipids are diagenetically unstable, and bone is a porous open system, allowing microbial/molecular flux. These 'soft tissues' have been reinterpreted as biofilms. Organic preservation versus contamination of dinosaur bone was examined by freshly excavating, with aseptic protocols, fossils and sedimentary matrix, and chemically/biologically analyzing them. Fossil 'soft tissues' differed from collagen chemically and structurally; while degradation would be expected, the patterns observed did not support this. 16S rRNA amplicon sequencing revealed that dinosaur bone hosted an abundant microbial community different from lesser abundant communities of surrounding sediment. Subsurface dinosaur bone is a relatively fertile habitat, attracting microbes that likely utilize inorganic nutrients and complicate identification of original organic material. There exists potential post-burial taphonomic roles for subsurface microorganisms.

50 years of scanning electron microscopy of bone-a comprehensive overview of the important discoveries made and insights gained into bone material properties in health, disease, and taphonomy

Bone is an architecturally complex system that constantly undergoes structural and functional optimisation through renewal and repair. The scanning electron microscope (SEM) is among the most frequently used instruments for examining bone. It offers the key advantage of very high spatial resolution coupled with a large depth of field and wide field of view. Interactions between incident electrons and atoms on the sample surface generate backscattered electrons, secondary electrons, and various other signals including X-rays that relay compositional and topographical information. Through selective removal or preservation of specific tissue components (organic, inorganic, cellular, vascular), their individual contribution(s) to the overall functional competence can be elucidated. With few restrictions on sample geometry and a variety of applicable sample-processing routes, a given sample may be conveniently adapted for multiple analytical methods. While a conventional SEM operates at high vacuum conditions that demand clean, dry, and electrically conductive samples, non-conductive materials (e.g., bone) can be imaged without significant modification from the natural state using an environmental scanning electron microscope. This review highlights important insights gained into bone microstructure and pathophysiology, bone response to implanted biomaterials, elemental analysis, SEM in paleoarchaeology, 3D imaging using focused ion beam techniques, correlative microscopy and in situ experiments. The capacity to image seamlessly across multiple length scales within the meso-micro-nano-continuum, the SEM lends itself to many unique and diverse applications, which attest to the versatility and user-friendly nature of this instrument for studying bone. Significant technological developments are anticipated for analysing bone using the SEM.

Dead and buried? Variation in post-mortem histories revealed through histotaphonomic characterisation of human bone from megalithic graves in Sweden

This study investigates possible variation in post-mortem histories during the Neolithic period in southwestern Sweden based on microscopic studies of human bone. Numerous megalithic graves were built in this region and good preservation conditions have left a rich skeletal record. After more than a hundred years of research, it is still a controversy whether or not these skeletal assemblages were the result of primary burials, or ossuaries where skeletonized remains were deposited. In this study we apply histological analysis to obtain insights into post-mortem histories and taphonomic processes affecting the human remains, potentially including funerary rituals. This type of analysis records the condition and traces of degradation found in skeletal material at a microscopic level. Human skeletal material from four different megalithic tombs in the Falbygden area has been sampled and analysed by thin-section light microscopy, and by scanning electron microscopy. The results of the study provide evidence of variation and changes in burial conditions for skeletal remains from the different graves, also for remains from the same grave. Extent of bioerosion varied, from extensive to moderate/arrested, to none. Bone samples from the same graves also differed in the type of staining and mineral inclusions, showing that the non-bioeroded samples relatively early post-mortem must have experienced an anoxic environment, and later a change to an aerated environment. This could be taken as an indication of primary burial somewhere else, but more likely reflect a special micro-environment occurring temporarily in some graves and parts of graves after the tombs were filled with soil and sealed by roof slabs. The study illustrates the usefulness of bone histological analysis in the reconstruction of post-mortem histories, revealing variations not discernible at macro-level that may aid in the interpretations of funerary rituals. However, the results also highlight the issues of equifinality. Based on current data and knowledge, several scenarios are possible. Further histotaphonomic work is advisable, including archaeological remains from megalithic tombs, and bones from taphonomic experiments.