Episodic, compression-driven fluid venting in layered sedimentary basins

Fluid venting phenomena are prevalent in sedimentary basins globally. Offshore, these localised fluid-expulsion events are archived in the geologic record via the resulting pockmarks at the sea-floor. Venting is widely interpreted to occur via hydraulic fracturing, which requires near-lithostatic pore pressures for initiation. One common driver for these extreme pressures is horizontal tectonic compression, which pressurises the entire sedimentary column over a wide region. Fluid expulsion leads to a sudden, local relief of this pressure, which then gradually recharges through continued compression, leading to episodic venting. Pressure recharge will also occur through pressure diffusion from neighboring regions that remain pressurised, but the combined role of compression and pressure diffusion in episodic venting has not previously been considered. Here, we develop a novel poroelastic model for episodic, compression-driven venting. We show that compression and pressure diffusion together set the resulting venting period. We derive a simple analytical expression for this venting period, demonstrating that pressure diffusion can significantly reduce the venting period associated with a given rate of compression and allowing this rate of compression to be inferred from observations of episodic venting. Our results indicate that pressure diffusion is a major contributor to episodic fluid venting in mudstone-dominated basins

Episodic fluid venting from sedimentary basins fuelled by pressurised mudstones

Subsurface sandstone reservoirs sealed by overlying, low-permeability layers provide capacity for long-term sequestration of anthropogenic waste. Leakage can occur if reservoir pressures rise sufficiently to fracture the seal. Such pressures can be generated within the reservoir by vigorous injection of waste or, over thousands of years, by natural processes. In either case, the precise role of intercalated mudstones in the long-term evolution of reservoir pressure remains unclear; these layers have variously been viewed as seals, as pressure sinks or as pressure sources. Here, we use the geological record of episodic fluid venting in the Levant Basin to provide striking evidence for the pressure-source hypothesis. We use a Bayesian framework to combine recently published venting data, which record critical subsurface pressures since $\sim$2 Ma, with a stochastic model of pressure evolution to infer a pressure-recharge rate of $\sim$30 MPa/Myr. To explain this large rate, we quantify and compare a range of candidate mechanisms. We find that poroelastic pressure diffusion from mudstones provides the most plausible explanation for these observations, amplifying the $\sim$1 MPa/Myr recharge caused by tectonic compression. Since pressurised mudstones are ubiquitous in sedimentary basins, pressure diffusion from mudstones is likely to promote seal failure globally

In Planta Production of Flock House Virus Transencapsidated RNA and Its Potential Use as a Vaccine

We have developed a transencapsidated vaccine delivery system based on the insect virus, Flock House virus (FHV). FHV is attractive due to its small genome size, simple organization, and non-pathogenic characteristics. With the insertion of a Tobacco mosaic virus (TMV) origin of assembly (Oa), the independently replicating FHV RNA1 can be transencapsidated by TMV coat protein. In this study we demonstrated that the Oa adapted FHV RNA1 transencapsidation process can take place in planta, by using a bipartite plant expression vector system, where TMV coat protein is expressed by another plant virus vector, Foxtail mosaic virus (FoMV). Dual infection in the same cell by both FHV and FoMV was observed. Though an apparent classical coat protein-mediated resistance repressed FHV expression, this was overcome by delaying inoculation of the TMV coat protein vector by three days after FHV vector inoculation. Expression of transgene marker in animals by these in vivo generated transencapsidated nanoparticles was confirmed by mouse vaccination, which also showed an improved vaccine response compared to similar in vitro produced vaccines

Nanoparticle Encapsidation of Flock House Virus by Auto Assembly of Tobacco Mosaic Virus Coat Protein

Tobacco Mosaic virus (TMV) coat protein is well known for its ability to self-assemble into supramolecular nanoparticles, either as protein discs or as rods originating from the ~300 bp genomic RNA origin-of-assembly (OA). We have utilized TMV self-assembly characteristics to create a novel Flock House virus (FHV) RNA nanoparticle. FHV encodes a viral polymerase supporting autonomous replication of the FHV genome, which makes it an attractive candidate for viral transgene expression studies and targeted RNA delivery into host cells. However, FHV viral genome size is strictly limited by native FHV capsid. To determine if this packaging restriction could be eliminated, FHV was adapted to express enhanced green fluorescent protein (GFP), to allow for monitoring of functional FHV RNA activity. Then TMV OA was introduced in six 3\u27 insertion sites, with only site one supporting functional FHV GFP expression. To create nanoparticles, FHV GFP-OA modified genomic RNA was mixed in vitro with TMV coat protein and monitored for encapsidation by agarose electrophoresis and electron microscopy. The production of TMV-like rod shaped nanoparticles indicated that modified FHV RNA can be encapsidated by purified TMV coat protein by self-assembly. This is the first demonstration of replication-independent packaging of the FHV genome by protein self-assembly

Nematode associates and susceptibility of a protected slug (Geomalacus maculosus) to four biocontrol nematodes

The impact of selected entomopathogenic nematodes and Phasmarhabditis hermaphrodita on the European-Union-protected slug Geomalacus maculosus and the sympatric Lehmannia marginata was investigated. There was no significant difference in mortality between slugs treated with nematodes and their controls. The presence of P. hermaphrodita in two G. maculosus cadavers may be the result of necromenic behaviour. This study constitutes the first record of P. californica in Europe

Cheating the locals: invasive mussels steal and benefit from the cooling effect of indigenous mussels

The indigenous South African mussel Perna perna gapes during periods of aerial exposure to maintain aerobic respiration. This behaviour has no effect on the body temperatures of isolated individuals, but when surrounded by conspecifics, beneficial cooling effects of gaping emerge. It is uncertain, however, whether the presence of the invasive mussel Mytilus galloprovincialis limits the ability of P. perna for collective thermoregulation. We investigated whether varying densities of P. perna and M. galloprovincialis influences the thermal properties of both natural and artificial mussel beds during periods of emersion. Using infrared thermography, body temperatures of P. perna within mixed artificial beds were shown to increase faster and reach higher temperatures than individuals in conspecific beds, indicating that the presence of M. galloprovincialis limits the group cooling effects of gaping. In contrast, body temperatures of M. galloprovincialis within mixed artificial mussel beds increased slower and exhibited lower temperatures than for individuals in beds comprised entirely of M. galloprovincialis. Interestingly, differences in bed temperatures and heating rates were largely dependent on the size of mussels, with beds comprised of larger individuals experiencing less thermal stress irrespective of species composition. The small-scale patterns of thermal stress detected within manipulated beds were not observed within naturally occurring mixed mussel beds. We propose that small-scale differences in topography, size-structure, mussel bed size and the presence of organisms encrusting the mussel shells mask the effects of gaping behaviour within natural mussel beds. Nevertheless, the results from our manipulative experiment indicate that the invasive species M. galloprovincialis steals thermal properties as well as resources from the indigenous mussel P. perna. This may have significant implications for predicting how the co-existence of these two species may change as global temperatures continue to rise

The novel sodium channel modulator GS‐458967 (GS967) is an effective treatment in a mouse model of SCN8A encephalopathy

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144249/1/epi14196.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144249/2/epi14196-sup-0001-SupInfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144249/3/epi14196_am.pd