Striped catfish (Pangasianodon hypophthalmus) exploit food sources across anaerobic decomposition- and primary photosynthetic production-based food chains.

Dietary information from aquatic organisms is instrumental in predicting biological interactions and understanding ecosystem functionality. In freshwater habitats, generalist fish species can access a diverse array of food sources from multiple food chains. These may include primary photosynthetic production and detritus derived from both oxic and anoxic decomposition. However, the exploitation of anoxic decomposition products by fish remains insufficiently explored. This study examines feeding habits of striped catfish (Pangasianodon hypophthalmus) at both adult and juvenile stages within a tropical reservoir, using stable carbon, nitrogen, and sulfur isotope ratios (δ13C, δ15N, and δ34S, respectively) and fatty acid (FA) analyses. The adult catfish exhibited higher δ15N values compared to primary consumers that feed on primary photosynthetic producers, which suggests ingestion of food sources originating from primary photosynthetic production-based food chains. On the other hand, juvenile catfish demonstrated lower δ15N values than primary consumers, correlating with low δ34S value and large proportions of bacterial FA but contained small proportions of polyunsaturated FA. This implies that juveniles utilize food sources from both anoxic decomposition and primary photosynthetic production-based food chains. Our results indicate that food chains based on anoxic decomposition can indeed contribute to the dietary sources of tropical fish species.

Film-Shaped Self-Powered Electro-Osmotic Micropump Array.

This paper reports a new concept of a film-shaped micropump array for biomedical perfusion. The detailed concept, design, fabrication process, and performance evaluation using prototypes are described. In this micropump array, an open circuit potential (OCP) is generated by a planar biofuel cell (BFC), which in turn generates electro-osmotic flows (EOFs) in multiple through-holes arranged perpendicular to the micropump plane. The micropump array is thin and wireless, so it can be cut like postage stamps, easily installed in any small location, and can act as a planar micropump in solutions containing the biofuels glucose and oxygen. Perfusion at local sites are difficult with conventional techniques using multiple separate components such as micropumps and energy sources. This micropump array is expected to be applied to the perfusion of biological fluids in small locations near or inside cultured cells, cultured tissues, living organisms, and so on.

Major contribution of sulfide-derived sulfur to the benthic food web in a large freshwater lake.

In freshwater systems, contributions of chemosynthetic products by sulfur-oxidizing bacteria in sediments as nutritional resources in benthic food webs remain unclear, even though chemosynthetic products might be an important nutritional resource for benthic food webs in deep-sea hydrothermal vents and shallow marine systems. To study geochemical aspects of this trophic pathway, we sampled sediment cores and benthic animals at two sites (90 and 50 m water depths) in the largest freshwater (mesotrophic) lake in Japan: Lake Biwa. Stable carbon, nitrogen, and sulfur isotopes of the sediments and animals were measured to elucidate the sulfur nutritional resources for the benthic food web precisely by calculating the contributions of the incorporation of sulfide-derived sulfur to the biomass and of the biogeochemical sulfur cycle supporting the sulfur nutritional resource. The recovered sediment cores showed increases in 34 S-depleted sulfide at 5 cm sediment depth and showed low sulfide concentration with high δ34 S in deeper layers, suggesting an association of microbial activities with sulfate reduction and sulfide oxidation in the sediments. The sulfur-oxidizing bacteria may contribute to benthic animal biomass. Calculations based on the biomass, sulfur content, and contribution to sulfide-derived sulfur of each animal comprising the benthic food web revealed that 58%-67% of the total biomass sulfur in the benthic food web of Lake Biwa is occupied by sulfide-derived sulfur. Such a large contribution implies that the chemosynthetic products of sulfur-oxidizing bacteria are important nutritional resources supporting benthic food webs in the lake ecosystems, at least in terms of sulfur. The results present a new trophic pathway for sulfur that has been overlooked in lake ecosystems with low-sulfate concentrations.

Bionic eye system mimicking microfluidic structure and intraocular pressure for glaucoma surgery training.

Among increasing eye diseases, glaucoma may hurt the optic nerves and lead to vision loss, the treatment of which is to reduce intraocular pressure (IOP). In this research, we introduce a new concept of the surgery simulator for Minimally Invasive Glaucoma Surgery (MIGS). The concept is comprised of an anterior eye model and a fluidic circulatory system. The model made of flexible material includes a channel like the Schlemm's canal (SC) and a membrane like the trabecular meshwork (TM) covering the SC. The system can monitor IOP in the model by a pressure sensor. In one of the MIGS procedures, the TM is cleaved to reduce the IOP. Using the simulator, ophthalmologists can practice the procedure and measure the IOP. First, considering the characteristics of human eyes, we defined requirements and target performances for the simulator. Next, we designed and manufactured the prototype. Using the prototype, we measured the IOP change before and after cleaving the TM. Finally, we demonstrated the availability by comparing experimental results and target performances. This simulator is also expected to be used for evaluations and developments of new MIGS instruments and ophthalmic surgery robots in addition to the surgical training of ophthalmologists.

A force measurement platform for a vitreoretinal surgical simulator using an artificial eye module integrated with a quartz crystal resonator.

To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane (ILM) peeling, we developed an artificial eye module comprising a quartz crystal resonator (QCR) force sensor and a strain body that serves as a uniform force transmitter beneath a retinal model. Although a sufficiently large initial force must be loaded onto the QCR force sensor assembly to achieve stable contact with the strain body, the highly sensitive and wide dynamic-range property of this sensor enables the eye module to detect the slight forceps contact force. A parallel-plate strain body is used to achieve a uniform force sensitivity over the 4-mm-diameter ILM peeling region. Combining these two components allowed for a measurable force range of 0.22 mN to 29.6 N with a sensitivity error within -11.3 to 4.2% over the ILM peeling area. Using this eye module, we measured the applied force during a simulation involving artificial ILM peeling by an untrained individual and compensated for the long-term drift of the obtained force data using a newly developed algorithm. The compensated force data clearly captured the characteristics of several types of motion sequences observed from video recordings of the eye bottom using an ophthalmological microscope. As a result, we succeeded in extracting feature values that can be potentially related to trainee skill level, such as the mean and standard deviation of the pushing and peeling forces, corresponding, in the case of an untrained operator, to 122.6 ± 95.2 and 20.4 ± 13.2 mN, respectively.

Trait Plasticity among Invasive Populations of the Ant Technomyrmex brunneus in Japan.

Characters in invasive populations often differ from those in the native range, and the ability to express different characters may enhance invasive potential. Ants are among the most pervasive and damaging invasive species, by virtue of their transportability and broad-ranging ecological interactions. Their success is often attributed to the ability to exhibit different characteristics in invasive populations, including the formation of large, unicolonial associations ('supercolonies'). It remains unclear, however, if such characteristics are a product or cause of the ecological dominance of invasive ants, and the advancement of our understanding has likely been restrained by the fact that studies to date have focused on a few globally important species with well-established invasions. In this study, we take advantage of an ongoing invasion of the tramp ant Technomyrmex brunneus in Japan to assess trait plasticity in the invasive range of this species. We find evidence for plasticity in social structure among island populations, with a supercolony evident on one of the three islands studied. Interestingly, we found no evidence of lower genetic diversity in this population, though natural isotope data indicate it was operating at a lower trophic level than other populations. These findings add weight to arguments that invasive species may benefit from the capacity to adaptively mould themselves to new ecological contexts.

Evolution of Reactions of a Fluoride Shuttle Battery at the Surfaces of BiF3 Microclusters Studied by In†Situ Raman Microscopy.

Fluoride shuttle batteries (FSBs), which utilize defluorination of metal fluorides and fluorination of the resultant metals, are expected to have high energy densities. In situ Raman microscopy was conducted during FSB reactions of a nearly-2D cluster of orthorhombic BiF3 microparticles partly embedded in a gold-plated film (o-BiF3 /gold). At a high overpotential, defluorination of the surface of an o-BiF3 particle (or cluster) was almost completed within approximately 120 s. At a low over potential, defluorination proceeded from the contours of the cluster that was in contact with the gold to the center of the cluster, suggesting that the rate-limiting process was electronic diffusion. Conversely, fluorination proceeded uniformly at the surface of the cluster to form BiF3 with a cubic structure (c-BiF3 ). The results will lead to the establishment of a strategy for efficient use of active materials with low electronic and ionic conductivities.

Microbial community structure in deep natural gas-bearing aquifers subjected to sulfate-containing fluid injection.

In the natural gas field located in central Japan, high concentrations of natural gases and iodide ions are dissolved in formation water and commercially produced in deep aquifers. In the iodine recovery process, the produced formation water is amended with sulfate, and this fluid is injected into gas-bearing aquifers, which may lead to infrastructure corrosion by hydrogen sulfide. In this study, we examined the microbial community in aquifers subjected to sulfate-containing fluid injection. Formation water samples were collected from production wells located at different distances from the injection wells. The chemical analysis showed that the injection fluid contained oxygen, nitrate, nitrite and sulfate, in contrast to the formation water, which had previously been shown to be depleted in these components. Sulfur isotopic analysis indicated that sulfate derived from the injection fluid was present in the sample collected from near the injection wells. Quantitative and sequencing analysis of dissimilatory sulfite reductase and 16S rRNA genes revealed that sulfate-reducing bacteria (SRB), sulfur-oxidizing bacteria, and anaerobic methanotrophic archaea (ANME) in the wells located near injection wells were more abundant than those in wells located far from the injection wells, suggesting that fluid injection stimulated these microorganisms through the addition of oxygen, nitrate, nitrite and sulfate to the methane-rich aquifers. The predominant taxa were assigned to the ANME-2 group, its sulfate-reducing partner SEEP-SRB1 cluster and sulfur-oxidizing Epsilonproteobacteria. These results provide important insights for future studies to support the development of natural gas and iodine resources in Japan.

Discovery and biogeochemistry of asphalt seeps in the North São Paulo Plateau, Brazilian Margin.

An initial multiple biogeochemical dataset was acquired from the first discovered asphalt seeps in the Brazil margin during deep-sea dive surveys in 2013 using a manned submersible. These surveys were conducted on the outer escarpment of the North São Paulo Plateau. Sediment cores taken from the submersible were processed for pore water and sediment biogeochemistry. The silica concentration, as a chemical geothermometer, showed a steep gradient in the pore water, which indicates the possibility of an active brine system operating in the seepage area. Rare earth elements were used as powerful tracers of chemical processes. Low rare earth element concentrations in both asphalt and Fe-Mn oxyhydroxide-phase sediments suggests that rare earth elements were released during the oil fractionation and biodegradation processes and further depleted under the reducing environment. The main bacterial communities of the sediment were Proteobacteria in the asphalt sites, while at non-asphalt sites, the main bacterial communities of sediment were Firmicutes. Stable carbon and nitrogen isotopes were used to determine the food sources of the heterotrophs, and results suggest that asphalt probably provides a carbon source for these benthic animals. This study may provide useful information to clarify the impact of heavy hydrocarbon seepage on the marine ecosystem.

Evaluation of the effect of the 2011 Tsunami on coastal forests by means of multiple isotopic analyses of tree-rings.

The March 2011 Mega-Tsunami in eastern Japan damaged at different degrees the black pine (Pinus thunbergii) forests along the coast. In order to evaluate the recovery of black pine four years later, tree-ring samples from 9 trees for the period 2002-2014 were analyzed for ring growth and stable isotopes (δ13C, δ15N and δ18O). The results showed that annual tree-ring width decreased approximately 70 % from the year 2011 to 2014 compared to the period previous to the tsunami (2002-2010). The multiple isotopic analyses showed that the reduction in growth was caused by soil salinity that prompted stomatal closure and an abrupt increase of tree-ring δ13C. Sea water deposition in the soil did not affect tree-ring δ18O values. Two years after the tsunami, decreasing tree-ring δ13C values caused by apparently photosynthetic recovery did not translate into radial tree-growth, indicating a possible shift in carbon allocation to foliage and mainly roots as a defense mechanism to sodium toxicity. The dual δ13C-δ18O model explains neither the limited growth nor the subsequent recovery in δ13C. Similarly tree-ring δ15N indicated that there was no difference in nitrogen availability before and after the tsunami, suggesting that nutrients were not a limitation but rather soil salinity.

Evaluation of nutrient and energy sources of the deepest known serpentinite-hosted ecosystem using stable carbon, nitrogen, and sulfur isotopes.

The Shinkai Seep Field (SSF) in the southern Mariana forearc discovered in 2010 is the deepest (~5,700 m in depth) known serpentinite-hosted ecosystem dominated by a vesicomyid clam, Calyptogena (Abyssogena) mariana. The pioneering study presumed that the animal communities are primary sustained by reducing fluid originated from the serpentinization of mantle peridotite. For understanding the nutrient and energy sources for the SSF community, this study conducted four expeditions to the SSF and collected additional animal samples such as polychaetes and crustaceans as well as sediments, fragments of chimneys developing on fissures of serpentinized peridotite, seeping fluid on the chimneys, and pore water within the chimneys. Geochemical analyses of seeping fluids on the chimneys and pore water of the chimneys revealed significantly high pH (~10) that suggest subseafloor serpentinization controlling fluid chemistry. Stable isotope systematics (carbon, nitrogen, and sulfur) among animals, inorganic molecules, and environmental organic matter suggest that the SSF animal community mostly relies on the chemosynthetic production while some organisms appear to partly benefit from photosynthetic production despite the great depth of SSF.

Interface structure between tetraglyme and graphite.

Clarification of the details of the interface structure between liquids and solids is crucial for understanding the fundamental processes of physical functions. Herein, we investigate the structure of the interface between tetraglyme and graphite and propose a model for the interface structure based on the observation of frequency-modulation atomic force microscopy in liquids. The ordering and distorted adsorption of tetraglyme on graphite were observed. It is found that tetraglyme stably adsorbs on graphite. Density functional theory calculations supported the adsorption structure. In the liquid phase, there is a layered structure of the molecular distribution with an average distance of 0.60 nm between layers.

In†Situ Raman Spectroscopic Studies on Concentration of Electrolyte Salt in Lithium-Ion Batteries by Using Ultrafine Multifiber Probes.

Lithium-ion batteries have attracted considerable attention due to their high power density. The change in concentration of salt in the electrolyte solution in lithium-ion batteries during operation causes serious degradation of battery performance. Herein, a new method of in situ Raman spectroscopy with ultrafine multifiber probes was developed to simultaneously study the concentrations of ions at several different positions in the electrolyte solution in deep narrow spaces between the electrodes in batteries. The total amount of ions in the electrolyte solution clearly changed during operation due to the low permeability of the solid-electrolyte interphase (SEI) at the anode for Li+ permeation. The permeability, which is a key factor to achieve high battery performance, was improved (enhanced) by adding film-forming additives to the electrolyte solution to modify the properties of the SEI. The results provide important information for understanding and predicting phenomena occurring in a battery and for designing a superior battery. The present method is useful for analysis in deep narrow spaces in other electrochemical devices, such as capacitors.

Comparative Analysis of Microbial Communities in Iron-Dominated Flocculent Mats in Deep-Sea Hydrothermal Environments.

UNLABELLED: It has been suggested that iron is one of the most important energy sources for photosynthesis-independent microbial ecosystems in the ocean crust. Iron-metabolizing chemolithoautotrophs play a key role as primary producers, but little is known about their distribution and diversity and their ecological role as submarine iron-metabolizing chemolithotrophs, particularly the iron oxidizers. In this study, we investigated the microbial communities in several iron-dominated flocculent mats found in deep-sea hydrothermal fields in the Mariana Volcanic Arc and Trough and the Okinawa Trough by culture-independent molecular techniques and X-ray mineralogical analyses. The abundance and composition of the 16S rRNA gene phylotypes demonstrated the ubiquity of zetaproteobacterial phylotypes in iron-dominated mat communities affected by hydrothermal fluid input. Electron microscopy with energy-dispersive X-ray microanalysis and X-ray absorption fine structure (XAFS) analysis revealed the chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species and the potential contribution of Zetaproteobacteria to the in situ generation. These results suggest that putative iron-oxidizing chemolithoautotrophs play a significant ecological role in producing iron-dominated flocculent mats and that they are important for iron and carbon cycles in deep-sea low-temperature hydrothermal environments. IMPORTANCE: We report novel aspects of microbiology from iron-dominated flocculent mats in various deep-sea environments. In this study, we examined the relationship between Zetaproteobacteria and iron oxides across several hydrothermally influenced sites in the deep sea. We analyzed iron-dominated mats using culture-independent molecular techniques and X-ray mineralogical analyses. The scanning electron microscopy-energy-dispersive X-ray spectroscopy SEM-EDS analysis and X-ray absorption fine structure (XAFS) analysis revealed chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species as well as the potential contribution of the zetaproteobacterial population to the in situ production. These key findings provide important information for understanding the mechanisms of both geomicrobiological iron cycling and the formation of iron-dominated mats in deep-sea hydrothermal fields.

Irreversible morphological changes of a graphite negative-electrode at high potentials in LiPF6-based electrolyte solution.

The degradation mechanism of a graphite negative-electrode in LiPF6-based electrolyte solution was investigated using the basal plane of highly oriented pyrolytic graphite (HOPG) as a model electrode. Changes in the surface morphology were observed by in situ atomic force microscopy. In the initial cathodic scan, a number of pits appeared at around 1.75 V vs. Li(+)/Li, and fine particles formed on the terrace of the HOPG basal plane at about 1.5 V vs. Li(+)/Li. The fine particles were characterized by spectroscopic analysis, such as X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy. We added one of the components to LiClO4-based electrolyte solution, and successfully reproduced the formation of pits and fine particles on the basal plane of HOPG. Based on these results, the formation mechanisms of pits and fine particle layers were proposed.

Effect of sulfide, osmotic, and thermal stresses on taurine transporter mRNA levels in the gills of the hydrothermal vent-specific mussel Bathymodiolus septemdierum.

Hydrothermal vent environmental conditions are characterized by high sulfide concentrations, fluctuating osmolality, and irregular temperature elevations caused by vent effluents. These parameters represent potential stressors for organisms that inhabit the area around hydrothermal vents. Here, we aimed to obtain a better understanding of the adaptation mechanisms of marine species to hydrothermal vent environments. Specifically, we examined the effect of sulfide, osmolality, and thermal stress on the expression of taurine transporter (TAUT) mRNA in the gill of the deep-sea mussel Bathymodiolus septemdierum, which is a dominant species around hydrothermal vent sites. We analyzed TAUT mRNA levels by quantitative real-time polymerase chain reaction (PCR) in the gill of mussels exposed to sulfide (0.1 or 1mg/L Na2S·9H2O), hyper- (115% seawater) and hypo- (97.5%, 95.5%, and 85% seawater) osmotic conditions, and thermal stresses (12°C and 20°C) for 24 and 48h. The results showed that mussels exposed to relatively low levels of sulfide (0.1mg/L) and moderate heat stress (12°C) exhibited higher TAUT mRNA levels than the control. Although hyper- and hypo-osmotic stress did not significantly change TAUT mRNA levels, slight induction was observed in mussels exposed to low osmolality. Our results indicate that TAUT is involved in the coping mechanism of mussels to various hydrothermal vent stresses.

Growth temperatures of archaeal communities can be estimated from the guanine-plus-cytosine contents of 16S rRNA gene fragments.

Prokaryote growth temperatures in environmental samples are difficult to measure because it is hard to culture viable prokaryotes in natural environments. We comprehensively surveyed growth temperatures and 16S rRNA sequences of prokaryotes to estimate their growth temperatures based on guanine-plus-cytosine contents (P(GC)) of their 16S rRNA sequences. We focused on archaea because of the wide range of growth temperatures within this group. Their minimum (Tmin), optimum (Topt) and maximum (Tmax) growth temperatures correlated strongly with PGC of their 16S rRNA genes. Linear regression equations were established to approximate Tmin, Topt and Tmax from P(GC). We also established a linear regression equation for calculating P(GC) of 16S rRNA genes based on the melting temperatures (Tm) of PCR fragments, without using a clone library or sequencing. Environmental samples were obtained from a wide variety of microbial natural habitats. Tm of archaeal 16S rRNA genes amplified by real-time PCR were determined by melting curve analysis. Based on those values, P(GC) of 16S rRNA genes and mean Tmin, Topt and Tmax were calculated using the linear regression equations. These temperatures correlated strongly with the in situ temperatures. Tmax agreed particularly well with these temperatures, suggesting many archaea live at their maximum growth temperatures.

Layered perovskite oxide: a reversible air electrode for oxygen evolution/reduction in rechargeable metal-air batteries.

For the development of a rechargeable metal-air battery, which is expected to become one of the most widely used batteries in the future, slow kinetics of discharging and charging reactions at the air electrode, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively, are the most critical problems. Here we report that Ruddlesden-Popper-type layered perovskite, RP-LaSr3Fe3O10 (n = 3), functions as a reversible air electrode catalyst for both ORR and OER at an equilibrium potential of 1.23 V with almost no overpotentials. The function of RP-LaSr3Fe3O10 as an ORR catalyst was confirmed by using an alkaline fuel cell composed of Pd/LaSr3Fe3O10-2x(OH)2x·H2O/RP-LaSr3Fe3O10 as an open circuit voltage (OCV) of 1.23 V was obtained. RP-LaSr3Fe3O10 also catalyzed OER at an equilibrium potential of 1.23 V with almost no overpotentials. Reversible ORR and OER are achieved because of the easily removable oxygen present in RP-LaSr3Fe3O10. Thus, RP-LaSr3Fe3O10 minimizes efficiency losses caused by reactions during charging and discharging at the air electrode and can be considered to be the ORR/OER electrocatalyst for rechargeable metal-air batteries.

Characteristics of microbial communities in crustal fluids in a deep-sea hydrothermal field of the suiyo seamount.

To directly access the sub-seafloor microbial communities, seafloor drilling has been done in a deep-sea hydrothermal field of the Suiyo Seamount, Izu-Bonin Arc, Western Pacific. In the present study, crustal fluids were collected from the boreholes, and the bacterial and archaeal communities in the fluids were investigated by culture-independent molecular analysis based on 16S rRNA gene sequences. Bottom seawater, sands, rocks, sulfide mound, and chimneys were also collected around the boreholes and analyzed for comparisons. Comprehensive analysis revealed the characteristics of the microbial community composition in the crustal fluids. Phylotypes closely related to cultured species, e.g., Alteromonas, Halomonas, Marinobacter, were relatively abundant in some crustal fluid samples, whereas the phylotypes related to Pelagibacter and the SUP05-group were relatively abundant in the seawater samples. Phylotypes related to other uncultured environmental clones in Alphaproteobacteria and Gammaproteobacteria were relatively abundant in the sand, rock, sulfide mound, and chimney samples. Furthermore, comparative analysis with previous studies of the Suiyo Seamount crustal fluids indicates the change in the microbial community composition for 3 years. Our results provide novel insights into the characteristics of the microbial communities in crustal fluids beneath a deep-sea hydrothermal field.

Fast measurement of dissolved inorganic carbon concentration for small-volume interstitial water by acid extraction and nondispersive infrared gas analysis.

We developed a system for measuring the total dissolved inorganic carbon (DIC) concentrations in interstitial water and hydrothermal fluid, which are hard to obtain in large volumes. The system requires a sample volume of only 500 µL, and it takes only 150 s per one sample. The detection limit of this system was estimated to be 66.6 µmol/kg with repeated analysis of CO(2)-free ultrapure water (n = 9). The precision of this nondispersive infrared (NDIR) system was ±3.1% of the relative standard deviations (2σ) by repeated CRM batch 104 (n = 10). This result is much larger than the required precision for oceanographic studies, but is comparable to a previous result of interstitial water analysis. An on-site trial showed a significant DIC enrichment in interstitial water of hydrothermally altered sediment, and is considered to occur by the mixing of hydrothermal fluid. This procedure will achieve carbon dioxide flux calculations from hydrothermal activities, and will bring a more accurate feature on the global carbon cycle.