Primordial synthesis of amines and amino acids in a 1958 Miller H2S-rich spark discharge experiment

Archived samples from a previously unreported 1958 Stanley Miller electric discharge experiment containing hydrogen sulfide (H(2)S) were recently discovered and analyzed using high-performance liquid chromatography and time-of-flight mass spectrometry. We report here the detection and quantification of primary amine-containing compounds in the original sample residues, which were produced via spark discharge using a gaseous mixture of H(2)S, CH(4), NH(3), and CO(2). A total of 23 amino acids and 4 amines, including 7 organosulfur compounds, were detected in these samples. The major amino acids with chiral centers are racemic within the accuracy of the measurements, indicating that they are not contaminants introduced during sample storage. This experiment marks the first synthesis of sulfur amino acids from spark discharge experiments designed to imitate primordial environments. The relative yield of some amino acids, in particular the isomers of aminobutyric acid, are the highest ever found in a spark discharge experiment. The simulated primordial conditions used by Miller may serve as a model for early volcanic plume chemistry and provide insight to the possible roles such plumes may have played in abiotic organic synthesis. Additionally, the overall abundances of the synthesized amino acids in the presence of H(2)S are very similar to the abundances found in some carbonaceous meteorites, suggesting that H(2)S may have played an important role in prebiotic reactions in early solar system environments.     

Characterization of Eyjafjallajokull volcanic ash particles and a protocol for rapid risk assessment

On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions.     

Melanin-concentrating hormone peptidergic system: Comparative morphology between muroid species

Melanin-concentrating hormone (MCH) is a conserved neuropeptide, predominantly located in the diencephalon of vertebrates, and associated with a wide range of functions. While functional studies have focused on the use of the traditional mouse laboratory model, critical gaps exist in our understanding of the morphology of the MCH system in this species. Even less is known about the nontraditional animal model Neotomodon alstoni (Mexican volcano mouse). A comparative morphological study among these rodents may, therefore, contribute to a better understanding of the evolution of the MCH peptidergic system. To this end, we employed diverse immunohistochemical protocols to identify key aspects of the MCH system, including its spatial relationship to another neurochemical population of the tuberal hypothalamus, the orexins. Three-dimensional (3D) reconstructions were also employed to convey a better sense of spatial distribution to these neurons. Our results show that the distribution of MCH neurons in all rodents studied follows a basic plan, but individual characteristics are found for each species, such as the preeminence of a periventricular group only in the rat, the lack of posterior groups in the mouse, and the extensive presence of MCH neurons in the anterior hypothalamic area of Neotomodon. Taken together, these data suggest a strong anatomical substrate for previously described functions of the MCH system, and that particular neurochemical and morphological features may have been determinant to species-specific phenotypes in rodent evolution.     

Pozzolanic Activity Assessment of LUSI (LUmpur SIdoarjo) Mud in Semi High Volume Pozzolanic Mortar

LUSI mud obtained from the mud volcano in Sidoarjo, Indonesia, is a viable aluminosilicate material to be utilized as pozzolanic material. LUSI is an abbreviation of the local name of the mud, i.e., Lumpur Sidoarjo, meaning Sidoarjo mud. This paper reports the results of an investigation to assess the pozzolanic activity of LUSI mud, especially in semi high volume pozzolanic mortar. In this case, the amount of mud incorporated is between 30% to 40% of total cementitious material, by mass. The content of SiO₂ in the mud is about 30%, whilst the total content of SiO₂, Fe₂O₃ and Al₂O₃ is more than 70%. Particle size and degree of partial cement replacement by treated LUSI mud affect the compressive strength, the strength activity index (SAI), the rate of pozzolanic activity development, and the workability of mortar incorporating LUSI mud. Manufacturing semi high volume LUSI mud mortar, up to at least 40% cement replacement, is a possibility, especially with a smaller particle size of LUSI mud, less than 63 μm. The use of a larger percentage of cement replacement by LUSI mud does not show any adverse effect on the water demand, as the flow of the fresh mortar increased with the increase of percentage of LUSI mud usage.     

Prokaryotic diversity of an active mud volcano in the Usu City of Xinjiang, China

The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi-arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem.     

Dysfunction of dendritic cells in aged C57BL/6 mice leads to failure of natural killer cell activation and of tumor eradication

The reciprocal activation of dendritic cells (DCs) and natural killer cells (NKs) plays a key role in both innate and adaptive immunity. The effect of aging on this cross-talk, a critical step in virus disease control and tumor immunology, has not been reported. Splenic DCs and NKs were purified from both young and old C57BL/6 mice and cocultured in the presence of polyinosinic:polycytidylic acid (poly I:C). The resulting activation of NKs was measured as expression of CD69 and secretion of IFN-γ. However, DCs from old mice could not activate NKs from either young or old mice in vitro or in vivo. In contrast, DCs from young mice efficiently activated NKs from both young and old mice. DCs from old mice were deficient in poly I:C-stimulated secretion of IL-15, IL-18, and IFN-α. Gene expression analysis revealed many other differences between DCs of old and young mice. Young mice strongly eradicated MHC class I-negative NK-sensitive RMA-S lymphoma mutant tumor cells, but old mice did not, in concert with the previous report that mousepox kills aged, but not young, C57BL/6 mice. Furthermore, a similar dysfunction of DC and its key role in NK activation was found in 27 out of 55 healthy human donors.Natural killer cells (NKs) and dendritic cells (DCs) are key players in the immune system. Previous studies have shown that their cross-talk plays a central role in the NK functions in tumor immunity and viral diseases (reviewed by ref. 1). DCs were reported to prime NK-mediated antitumor responses in 1999 (2). A few years later, the reciprocal interaction of DCs and NKs during viral infection was also described (3). Cytokines from DCs as well as cell–cell contact were shown to enhance NK function. DCs secreted IL-12 and IL-18, which promoted cytokine production by NKs (4, 5). Further, membrane-bound IL-15/15Rα on DCs is important in promoting NK survival and proliferation (6–8), and type I IFNs are crucial in the induction of NK cytotoxicity. In addition, some surface molecules on DCs—for example, CD40, CD48, CD70, CD80, CD86, major histocompatibility complex class I-related chain A/B (MICA/B), leukocyte function-associated Ag-1 (LFA-1), and chemokine (C-X3-C motif) ligand 1 (CX3CL1)—have been reported to be involved in the effect of DCs on NKs (1).It is well known that aged humans are more susceptible to malignancies and infectious diseases and less responsive to vaccination because of immunosenescence—that is, progressive deterioration in immune function with aging. Increasing evidence shows aging affects many cells in both innate immunity and adaptive immunity (9). For example, impairment of DC and macrophage functions, including phagocytic activity, cytokine secretion, wound repair, and antigen presentation, were observed (10, 11). In T cells, a shift from the naïve to memory phenotype, a decreased proliferative response, and impaired cytolytic activity were found (12). Some of these defects in cell functions are intrinsic, whereas others might be the consequence of the complicated interactions between immune cells (13). As key cells in innate immunity, functional changes in both NKs and DCs with aging were described. For example, increased numbers of NKs, decreased NK cytotoxicity on a per-cell basis, and reduced levels of cytokines and chemokines upon activation were reported in humans (14). Importantly, aged C57BL/6 mice lost their resistance to mousepox due to a decrease in numbers of NKs and impaired trafficking, a phenomenon not found in several other mouse strains (15). For DCs, aging leads to decreased dendritic cell-specific CD209 (DC-SIGN) expression on immature bone marrow-derived cells (BMDCs) without affecting their function in T-cell priming and Toll-like receptor (TLR) response (16, 17). In a tumor antigen system, BMDCs from aged mice were less efficient in stimulating antigen-specific T cells and displayed defective trafficking (18). However, to our knowledge, the effect of aging on DC-induced NK activation has not been studied. DC/NK cross-talk is a critical factor in maturation of the immune system, affecting both innate and adaptive immunity. In the present work, CD11c+ DCs and DX5+ (CD49b) NKs purified from the spleens of young and aged C57BL/6 mice were cocultured in the presence of polysinosinic:polycytidylic acid (poly I:C), together with corresponding in vivo experiments, to study the effect of aging on this system.     

Microstructure and Durability Performance of Mortars with Volcanic Powder from Calbuco Volcano (Chile) after 4 Hardening Years

One of the most popular ways to lessen the impact of the cement industry on the environment consists of substituting clinker by additions. The service life required for real construction elements is generally long, so it would be interesting to obtain information about the effects of new additions after a hardening period of several years. Analyzed here are the effects of the incorporation of volcanic ashes, coming from Calbuco volcano’s last eruption (Chile), as clinker replacement, in the durability and pore structure of mortars, after approximately 4 hardening years (1500 days), in comparison with reference specimens without additions. The substitution percentages of clinker by volcanic powder studied were 10% and 20%. The microstructure was characterized with mercury intrusion porosimetry and impedance spectroscopy. In order to evaluate the pozzolanic activity of the volcanic powder after 1500 days, differential thermal analyses were performed. Water absorption after immersion, steady-state diffusion coefficient and length change were also studied. In accordance with the results obtained, the 10% and 20% substitution of clinker by volcanic powder from the Calbuco volcano showed beneficial effects in the mortars after 4 years, especially regarding the microstructure and chloride diffusion, without noticeable influence in their water absorption.     

From the Cover: Geothermal activity helps life survive glacial cycles

Climate change has played a critical role in the evolution and structure of Earth’s biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this “geothermal glacial refugia” hypothesis has yet been undertaken, but Antarctica provides a unique setting for doing so. The continent has experienced repeated glaciations that most models indicate blanketed the continent in ice, yet many Antarctic species appear to have evolved in almost total isolation for millions of years, and hence must have persisted in situ throughout. How could terrestrial species have survived extreme glaciation events on the continent? Under a hypothesis of geothermal glacial refugia and subsequent recolonization of nongeothermal regions, we would expect to find greater contemporary diversity close to geothermal sites than in nongeothermal regions, and significant nestedness by distance of this diversity. We used spatial modeling approaches and the most comprehensive, validated terrestrial biodiversity dataset yet created for Antarctica to assess spatial patterns of diversity on the continent. Models clearly support our hypothesis, indicating that geothermally active regions have played a key role in structuring biodiversity patterns in Antarctica. These results provide critical insights into the evolutionary importance of geothermal refugia and the history of Antarctic species.Climate change has played a fundamental role in the evolution and structure of Earth’s biodiversity (1, 2). Many contemporary diversity and distribution patterns, for example, appear to have been driven largely by the glacial and interglacial cycles of the Pleistocene, particularly latitudinal range changes with species moving toward glaciers that are receding (or away from those that are growing) (3, 4). Recent evidence indicates, however, that diverse life must have persisted throughout the Last Glacial Maximum (LGM) within areas thought to have been covered by large ice sheets (5–8).Several disparate studies raise the possibility that geothermal areas might act as long-term refugia for a range of species under glacial conditions. These studies include the inferred persistence of a subterranean amphipod species in geothermally created refugia under the Icelandic ice cap (9), of a Patagonian crab in hot springs (10), of bryophytes on the isolated South Sandwich Islands of the maritime Antarctic (11), and of marine life during Snowball Earth glaciations in the Neoproterozoic (12). No comprehensive assessment of this “geothermal glacial refugia” hypothesis (11) has, however, yet been undertaken.The isolated and heavily glaciated continent of Antarctica presents an ideal physical setting in which to test this hypothesis. A striking discrepancy exists between geological and glaciological evidence that Antarctica was heavily glaciated at the LGM [with ice extending offshore to the edge of the continental shelf for the West Antarctic Ice Sheet and at least to midshelf areas for much of the East Antarctic Ice Sheet (13)] and biological evidence indicating that many Antarctic terrestrial taxa have existed on the continent for millions of years (e.g., refs. 14–19). Indeed, it is becoming increasingly apparent that, with the exception of highly mobile marine birds and mammals, little natural colonization of Antarctica has occurred since the LGM (3). How did Antarctic terrestrial species [many of which are endemic (19–22)] that require an ice-free habitat, such as microarthropods, nematodes, and mosses, survive on what is thought to have been a continent almost completely covered in ice?Geothermal sites may hold the answer. Numerous Antarctic volcanoes are currently active or have been active since and during the LGM, and these form three general clusters: the northern Antarctic Peninsula, Marie Byrd Land, and Victoria Land (23) (Fig. 1A). Ice-free terrain close to active craters, lower altitude ice-free geothermal ground (e.g., heated ground and ponds, steam fields, fumaroles), and ice caves formed by geothermal steam (24) could have existed throughout the Pleistocene (11), providing habitable environments that allowed Antarctic plants and invertebrates to survive on the continent. Recent geological estimates of ice thicknesses during the past 10 million years suggest that the ice cover was generally thinner than was previously thought, raising the likelihood of small, ice-free rocky patches (“nunataks”) being present (25, 26). However, although such nunataks could have harbored some life, many nunatak fauna are unique to such environments or to specific parts of the continent (27–29), and nunataks thus cannot explain the persistence of a wider range of Antarctic species, especially coastal species, throughout the LGM (30). Similarly, although the McMurdo Dry Valleys are known to have been partly ice-free at the LGM (31, 32), supporting some life, typically low moisture levels drastically limit diversity in this region (24, 25). Areas of greater biodiversity in Antarctica are usually thought to represent refugia of some kind that must have escaped the full consequences of various periods of glaciation, mostly as a consequence of typical geophysical features, such as permanently ice-free ridges or ablation valleys (33, 34). By contrast, little mention is made of the possibility of geothermal glacial refugia for anything but currently heated sites.Open in a separate windowFig. 1.(A) Map of sites used in modeling analyses, classified as large volcanic (red), small volcanic (orange), nonvolcanic geothermal (pink), or nongeothermal (yellow). The circles show sampling units as used in the modeling analyses; these sites were areas with a radius of 100 km centered on an ice-free geothermal (e.g., volcano summit) or nongeothermal site, with species richness for each unit used as the modeling response variable [models tested effects of (i) a unit being geothermal or not and (ii) distance of nongeothermal units from the nearest geothermal]. The Antarctic Peninsula and “continental” Antarctica were analyzed separately; the division between these regions is indicated by a black dashed line. Broadly, there are three “clusters” of volcanoes in Antarctica, which are indicated here by dashed red ellipses. (B) Partial dependence plot shows the relationship of the estimated species richness (S_jack2) with distance from geothermal sites (green solid line and right y axis) and relationship of the log of the contribution of sites to nestedness (blue dashed line and left y axis) with increasing distance from the nearest geothermal site, for plants on the Antarctic Peninsula.Here, through broad-scale spatial analysis of terrestrial biodiversity patterns in Antarctica, we directly test the geothermal refugia hypothesis. Nearly 39,000 spatially explicit occurrence records of 1,823 taxa south of 60° S have recently been compiled into the most comprehensive biodiversity database of Antarctic terrestrial taxa available to date (35). We used this dataset and spatial modeling approaches to assess diversity patterns in Antarctica in relation to the locations of geothermal areas. Postglacial population expansion away from LGM refugia is typically marked by a distinct reduction in diversity in recolonized vs. refugial regions (36–39) [including intraspecific genetic diversity (15, 31, 32)]. Under a hypothesis that geothermal refugia allowed persistence of Antarctic species throughout recent glacial periods, species richness is predicted to be highest close to geothermally active areas and lower in nonactive regions, with significant nestedness (40) of taxa from high- to low-richness areas, consistent with postglacial recolonization of more distant sites by a subset of the refugial taxa.