Detecting ancient life : Investigating the nature and origin of possible stromatolites and associated calcite from a one billion year old lake

ATB acknowledges the hospitality of the North West Highlands Geopark in July 2017. DW acknowledges funding from the Australian Research Council via the Future Fellowship scheme (FT 140100321).Peer reviewedPostprin

Paleoecology and paleoceanography of the Athel silicilyte, Ediacaran-Cambrian boundary, Sultanate of Oman

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100–200 m) at the Ediacaran–Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time-equivalent shallow-water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent-extractable bitumen, and measured whole-rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient-rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment-starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans

Residents\u27 Perceptions of Community and Environmental Impacts From Development of Natural Gas in the Marcellus Shale: A Comparison of Pennsylvania and New York Cases

Communities experiencing rapid growth due to energy development (‘boomtowns’) have reported positive and negative impacts on community and individual well-being. The perceptions of impacts vary according to stage of energy development as well as experience with extractive industries. Development of the Marcellus Shale provides an opportunity to examine these impacts over time and across geographic and historical contexts. This paper describes case study research in Pennsylvania and New York to document preliminary impacts of development occurring there. Cases vary by level of development and previous extractive history. The study finds that, in areas with low population density, higher levels of development lead to a broader awareness of natural gas impacts, both positive and negative. Participants draw from the regional history of extraction to express environmental concern despite direct, local experience. Our findings suggest the need to track these perceptions during development, and as individuals and communities react and adapt to the impacts

Public perception of the relationship between climate change and unconventional gas development ('fracking') in the US

Fracking’, or unconventional gas development via hydraulic fracturing (hereafter ‘UGD’), has been closely tied to global climate change in academic discourse. Researchers have debated the life cycle emissions of shale gas versus coal, rates of methane leakage from wellhead production and transmission infrastructure, the extent to which coal would be displaced by gas as a source of energy, the appropriate time-scale for accounting for the global warming potentials of methane and carbon dioxide, surface versus airborne methane measurements, and the effect of lowered energy prices on gas consumption. Little research, however, has examined the degree to which these potential connections between UGD and climate change are relevant to the general public. This article presents two surveys, one of a representative national (US) sample and one of a representative sample of residents in the Marcellus Shale region of Pennsylvania and New York. It examines whether respondents associated UGD with climate change, and the relationship between this association and their support for, or opposition to, UGD. The results reveal that beliefs about many other potential impacts of UGD explain more variation in support and opposition than do beliefs about UGD’s association with climate change. Furthermore, most other impacts of UGD are viewed as having more effect on quality of life if they were to occur, at least amongst the Marcellus Shale survey sample. The article concludes with implications of the findings for policy and communication on UGD

Response of Quercus ilex seedlings to Phytophthora spp. root infection in a soil infestation test

[EN] Phytophthora species are the main agents associated with oak (Quercus spp.) decline, together with the changing environmental conditions and the intensive land use. The aim of this study was to evaluate the susceptibility of Quercus ilex to the inoculation with eight Phytophthora species. Seven to eight month old Q. ilex seedlings grown from acorns, obtained from two Spanish origins, were inoculated with P. cinnamomi, P. cryptogea, P. gonapodyides, P. megasperma, P. nicotianae, P. plurivora, P. psychrophila and P. quercina. All Phytophthora inoculated seedlings showed decline and symptoms including small dark necrotic root lesions, root cankers, and loss of fine roots and tap root. The most aggressive species were P. cinnamomi, P. cryptogea, P. gonapodyides, P. plurivora and P. psychrophila followed by P. megasperma., while Phytophthora quercina and P. nicotianae were the less aggressive species. Results obtained confirm that these Phytophthora species could constituted a threat to Q. ilex ecosystems and the implications are further discussed.The authors are grateful to A. Solla and his team from the Centro Universitario de Plasencia-Universidad de Extremadura (Spain) for helping in the acorns collection and to the CIEF (Centro para la Investigación y Experimentación Forestal, Generalitat Valenciana, Valencia, Spain) for providing the acorns. This research was supported by funding from the project AGL2011- 30438-C02-01 (Ministerio de Economía y Competitividad, Spain).Mora-Sala, B.; Abad Campos, P.; Berbegal Martinez, M. (2018). Response of Quercus ilex seedlings to Phytophthora spp. root infection in a soil infestation test. European Journal of Plant Pathology. https://doi.org/10.1007/s10658-018-01650-6SÁlvarez, L. A., Pérez-Sierra, A., Armengol, J., & García-Jiménez, J. (2007). 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The Plant Pathogen Phytophthora andina Emerged via Hybridization of an Unknown Phytophthora Species and the Irish Potato Famine Pathogen, P. infestans

Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c

The Ascomycete Verticillium longisporum Is a Hybrid and a Plant Pathogen with an Expanded Host Range

Hybridization plays a central role in plant evolution, but its overall importance in fungi is unknown. New plant pathogens are thought to arise by hybridization between formerly separated fungal species. Evolution of hybrid plant pathogens from non-pathogenic ancestors in the fungal-like protist Phytophthora has been demonstrated, but in fungi, the most important group of plant pathogens, there are few well-characterized examples of hybrids. We focused our attention on the hybrid and plant pathogen Verticillium longisporum, the causal agent of the Verticillium wilt disease in crucifer crops. In order to address questions related to the evolutionary origin of V. longisporum, we used phylogenetic analyses of seven nuclear loci and a dataset of 203 isolates of V. longisporum, V. dahliae and related species. We confirmed that V. longisporum was diploid, and originated three different times, involving four different lineages and three different parental species. All hybrids shared a common parent, species A1, that hybridized respectively with species D1, V. dahliae lineage D2 and V. dahliae lineage D3, to give rise to three different lineages of V. longisporum. Species A1 and species D1 constituted as yet unknown taxa. Verticillium longisporum likely originated recently, as each V. longisporum lineage was genetically homogenous, and comprised species A1 alleles that were identical across lineages

The Endogenous Th17 Response in NO<inf>2</inf>-Promoted Allergic Airway Disease Is Dispensable for Airway Hyperresponsiveness and Distinct from Th17 Adoptive Transfer

Severe, glucocorticoid-resistant asthma comprises 5-7% of patients with asthma. IL-17 is a biomarker of severe asthma, and the adoptive transfer of Th17 cells in mice is sufficient to induce glucocorticoid-resistant allergic airway disease. Nitrogen dioxide (NO2) is an environmental toxin that correlates with asthma severity, exacerbation, and risk of adverse outcomes. Mice that are allergically sensitized to the antigen ovalbumin by exposure to NO2 exhibit a mixed Th2/Th17 adaptive immune response and eosinophil and neutrophil recruitment to the airway following antigen challenge, a phenotype reminiscent of severe clinical asthma. Because IL-1 receptor (IL-1R) signaling is critical in the generation of the Th17 response in vivo, we hypothesized that the IL-1R/Th17 axis contributes to pulmonary inflammation and airway hyperresponsiveness (AHR) in NO2-promoted allergic airway disease and manifests in glucocorticoid-resistant cytokine production. IL-17A neutralization at the time of antigen challenge or genetic deficiency in IL-1R resulted in decreased neutrophil recruitment to the airway following antigen challenge but did not protect against the development of AHR. Instead, IL-1R-/- mice developed exacerbated AHR compared to WT mice. Lung cells from NO2-allergically inflamed mice that were treated in vitro with dexamethasone (Dex) during antigen restimulation exhibited reduced Th17 cytokine production, whereas Th17 cytokine production by lung cells from recipient mice of in vitro Th17-polarized OTII T-cells was resistant to Dex. These results demonstrate that the IL-1R/Th17 axis does not contribute to AHR development in NO2-promoted allergic airway disease, that Th17 adoptive transfer does not necessarily reflect an endogenously-generated Th17 response, and that functions of Th17 responses are contingent on the experimental conditions in which they are generated. © 2013 Martin et al