Combined approach to estimate the depth of the magma surface in a shallow conduit at Aso volcano, Japan

Open-vent volcanoes provide opportunities to perform various methods of observation that can be used to study shallow plumbing systems. The depth of the magma–air interface in the shallow portion of the conduit can be used as an indicator of the volcanic activity of open-vent volcanoes. Although there are many methods used to estimate the depth, most of them cannot constrain the depth to a narrow range due to other unknown parameters. To constrain the depth more accurately, we combine two methods commonly used for estimating the depth of the magma–air interface. They consider the acoustic resonant frequency and the time delay of arrivals between the seismic and infrasound signals of explosions. Both methods have the same unknown parameters: the depth of the magma–air interface and the sound velocity inside the vent. Therefore, these unknowns are constrained so that both the observed resonant frequency and time delay can be explained simultaneously. We use seismo-acoustic data of Strombolian explosions recorded in the vicinity of Aso volcano, Japan, in 2015. The estimated depths and the sound velocities are 40–200 m and 300–680 m/s, respectively. The depth range is narrower than that of a previous study using only the time delay of arrivals. However, only a small amount of the observed data can be used for the estimation, as the rest of the data cannot provide realistic depths or sound velocities. In particular, a wide distribution of the observed time delay data cannot be explained by our simple assumptions. By considering a more complicated environment of explosions, such as source positions of explosions distributed across the whole surface of a lava pond in the conduit, most of the observed data can be used for estimation. This suggests that the factor controlling the observed time delay is not as simple as generally expected

Biosensing Techniques in Yeast: G-Protein Signaling and Protein-Protein Interaction Assays for Monitoring Ligand Stimulation and Oligomer Formation of Heterologous GPCRs

Guanine nucleotide-binding proteins (G-proteins) act as transducers of external stimuli for intracellular signaling, and control various cellular processes in cooperation with seven transmembrane G-protein-coupled receptors (GPCRs). Because GPCRs constitute the largest family of eukaryotic membrane proteins and enable the selective recognition of a diverse range of molecules (ligands), they are the major molecular targets in pharmaceutical and medicinal fields. In addition, GPCRs have been known to form heteromers as well as homomers, which may result in vast physiological diversity and provide opportunities for drug discovery. G-proteins and their signal transduction machinery are universally conserved in eukaryotes; thereby, the yeast Saccharomyces cerevisiae has been used to construct artificial in vivo GPCR biosensors. In this chapter, we focus on the yeast-based GPCR biosensors that can detect ligand stimulation and oligomer formation, and summarize their techniques using the G-protein signaling and protein-protein interaction assays

Temporal variation in the depth of the magma surface at Aso volcano in 2014–2015

Monitoring the depth of the magma surface at open-vent volcanoes can be a practical tool to infer temporal variations in the magma supply during an eruption. We focus on the magmatic eruption of Aso volcano in 2014–2015 to estimate the temporal change in the depth of the magma surface, and show that this needs to be coupled with an understanding of the shallow conduit geometry if it is to be done in a representative manner. The eruption lasted 5 months from November 2014 and ending with a crater floor collapse in May 2015. During the eruption, we recorded seismo-acoustic waveforms related to frequent Strombolian explosions. The infrasound signals show several distinct peak frequencies derived from acoustic resonance inside the vent. We estimate the depth of the magma surface using the time delay of seismo-acoustic signals and the peak frequency of infrasound signals. In addition, the temporal variation in the shape of the conduit is constrained by the overtone frequency of the acoustic resonance. From the beginning of the eruption to early-January 2015, the magma surface was located at a depth of ∼ 200 m, and the conduit was a cylindrical pipe. Later, between January and February, the magma surface rose to ∼ 120 m, and the shape of the conduit changed to a conical frustum flaring inside. This finding indicates that the magma was injected into the shallow conduit and that it heated and weakened the conduit wall near the magma surface. Before the cessation of the magmatic eruption, the magma surface dropped by approximately 70 m. This magma drainage and, primarily, the instability of the conduit shape caused the crater floor to collapse. We show the possibility of tracking and assessing the depth of the magma surface and the shallow conduit geometry even with limited seismo-acoustic observations

Targeting cancer cell-specific RNA interference by siRNA delivery using a complex carrier of affibody-displaying bio-nanocapsules and liposomes

BACKGROUND: Small interfering RNA (siRNA) has attracted attention in the field of nucleic acid medicine as a RNA interference (RNAi) application that leads to gene silencing due to specific messenger RNA (mRNA) destruction. However, since siRNA is unstable in blood and unable to cross the cell membrane, encapsulation of siRNA into a carrier is required. RESULTS: In this study, we used a carrier that combined Z(HER2)-displaying bio-nanocapsule (derived from hepatitis B virus surface antigen) and liposomes in a complex in order to investigate the feasibility of effective and target-cell-specific RNAi applications. As a result, by observing RNAi only in HER2-expressing breast cancer cells, using our proposed methodology, we successfully demonstrated target-cell-specific delivery and effective function expression of siRNA. CONCLUSIONS: These findings show that, in the field of nucleic acid medicine, Z(HER2)-BNC/LP can be a useful carrier for siRNA delivery, and could also become a useful tool for gene silencing and to accomplish protein knock-down

A display of pH-sensitive fusogenic GALA peptide facilitates endosomal escape from a Bio-nanocapsule via an endocytic uptake pathway

BACKGROUND: An affibody-displaying bio-nanocapsule (Z(HER2)-BNC) with a hepatocyte specificity derived from hepatitis B virus (HBV) was converted into an affibody, Z(HER2), that recognizes HER2 receptors. This affibody was previously reported to be the result of the endocytosis-dependent specific uptake of proteins and siRNA into target cancer cells. To assist the endosomal escape of inclusions, a helper lipid with pH-sensitive fusogenic ability (1,2-dioleoyl-sn-glycero-3-phos phoethanolamine; DOPE) was conjugated with a Z(HER2)-BNC. FINDINGS: In this study, we displayed a pH-sensitive fusogenic GALA peptide on the surface of a particle in order to confer the ability of endosomal escape to a Z(HER2)-BNC. A GALA-displaying Z(HER2)-BNC purified from yeast uneventfully formed a particle structure. Furthermore, endosomal escape of the particle was facilitated after endocytic uptake and release of the inclusions to the cytoplasm without the cell toxicity. CONCLUSION: The genetic fusion of a GALA peptide to the virus-like particle confers the ability of endosomal escape