Social Behaviours under Anaerobic Conditions in Pseudomonas aeruginosa

Pseudomonas aeruginosa is well adapted to grow in anaerobic environments in the presence of nitrogen oxides by generating energy through denitrification. Environmental cues, such as oxygen and nitrogen oxide concentrations, are important in regulating the gene expression involved in this process. Recent data indicate that P. aeruginosa also employs cell-to-cell communication signals to control the denitrifying activity. The regulation of denitrification by these signalling molecules may control nitric oxide production. Nitric oxide, in turn, functions as a signalling molecule by activating certain regulatory proteins. Moreover, under denitrifying conditions, drastic changes in cell physiology and cell morphology are induced that significantly impact group behaviours, such as biofilm formation

Inhibitory neurons exhibit high controlling ability in the cortical microconnectome

脳が安定して活動を続けられるメカニズムの一端を解明 --新皮質で、抑制性細胞は他細胞を制御しやすいトポロジカルな位置取りをする--. 京都大学プレスリリース. 2021-04-09.The brain is a network system in which excitatory and inhibitory neurons keep activity balanced in the highly non-random connectivity pattern of the microconnectome. It is well known that the relative percentage of inhibitory neurons is much smaller than excitatory neurons in the cortex. So, in general, how inhibitory neurons can keep the balance with the surrounding excitatory neurons is an important question. There is much accumulated knowledge about this fundamental question. This study quantitatively evaluated the relatively higher functional contribution of inhibitory neurons in terms of not only properties of individual neurons, such as firing rate, but also in terms of topological mechanisms and controlling ability on other excitatory neurons. We combined simultaneous electrical recording (~2.5 hours) of ~1000 neurons in vitro, and quantitative evaluation of neuronal interactions including excitatory-inhibitory categorization. This study accurately defined recording brain anatomical targets, such as brain regions and cortical layers, by inter-referring MRI and immunostaining recordings. The interaction networks enabled us to quantify topological influence of individual neurons, in terms of controlling ability to other neurons. Especially, the result indicated that highly influential inhibitory neurons show higher controlling ability of other neurons than excitatory neurons, and are relatively often distributed in deeper layers of the cortex. Furthermore, the neurons having high controlling ability are more effectively limited in number than central nodes of k-cores, and these neurons also participate in more clustered motifs. In summary, this study suggested that the high controlling ability of inhibitory neurons is a key mechanism to keep balance with a large number of other excitatory neurons beyond simple higher firing rate. Application of the selection method of limited important neurons would be also applicable for the ability to effectively and selectively stimulate E/I imbalanced disease states

The first total synthesisi of (±)-chanoclavine-Ⅰ acid and an alternative total synthesisi of (±)-chanoclavine-Ⅰ

金沢大学大学院自然科学研究科生理活性物質科学金沢大学薬学

Effect of carbon surface on degradation of supercapacitors in a negative potential range

The stability of supercapacitors is the key factor for their use under high temperature, high voltage and long-term durability. To improve the supercapacitor stability, there is a need to understand the degradation mechanism. In this work, the degradation sites in a carbon electrode at negative potential range are investigated in two common organic electrolytes: 1 M Et4NBF4 dissolved in propylene carbonate and in acetonitrile. To elucidate the common factor over a wide range of carbon materials, we examined eight kinds of carbon materials including activated carbons, carbon blacks, zeolite-template carbon (high surface area and a large amount of carbon edge sites) and graphene mesosponge (high surface area and a little amount of carbon edge sites). Their surface structures are distinguished into two regions: carbon basal planes and edge sites by nitrogen physisorption and high-sensitivity temperature-programmed desorption up to 1800 °C. Unlike the degradation at positive potential range, initial degradation reactions at negative potential range occur mainly on the carbon basal planes rather than the edge sites. This finding is corroborated by the theoretical calculation.This work was supported by JSPS KAKENHI (grant Nos. 17H01042 and 19H00913); the Dynamic Alliance for Open Innovation Bridging Human, Environment, and Materials program; and the Network Joint Research Centre for Materials and Devices. R. T. acknowledges the China Scholarship Council for the financial support. MINECO and FEDER (CTQ2015-66080-R MINECO/FEDER) are acknowledged for financial support

737–1 Heart Fatty Acid-binding Protein and Myoglobin can Accurately Detect Successful Reperfusion as Early as 15 Minutes After Reperfuslon

Human heart fatty acid-binding protein (FABP) is an abundant low molecular weight protein in cytoplasm of myocardial cell similar to myoglobin (Mb). To evaluate whether FABP can also detect successful reperfusion very early like Mb, we examined serum FABP and Mb levels in 45 patients (pts) undergoing PTCR or PTCA within 6 hours after the onset of acute myocardial infarction. Coronary angiography was performed every 5minutes (min) during reperfusion therapy to determine the exact time of reperfusion. In 30 pts with reperfusion (reperfused group: TIMI grade 3 [23 pts] and grade 2 [7 pts]), serum samples were taken just before and at 15, 30 and 60min after initial angiographic confirmation of reperfusion. In 15 pts without reperfusion (nonreperfused group), serum samples were taken just before and at 15, 30 and 60min after the initiation of therapy. FABP was measured by competitive enzyme immunoassay and Mb by latex agglutination turbidimetry. The FABP ratio (FABP after/FABP before) and Mb ratio (Mb after/Mb before) were calculated. FABP and Mb levels increased rapidly, peaked within 60min after reperfusion. The FABP and Mb ratios in the reperfused group significantly (p<0.01) exceeded those in the nonreperfused group at 15, 30 and 60 min. The sensitivity (Sen) and specificity (Spe) of these markers for reperfusion were as follows:Criteria15 min30 min60 minSenSpeSenSpeSenSpeFABP ratio>1.6*93%100%97%100%100%100%Mb ratio>2.4**90%100%93%100%100%100%*mean +2SD at 60 min in the nonreperfused group**published criteriaConclusionFABP, like Mb could accurately detect successful reperfusion as early as 15min after reperfusion and could provide a high level of accuracy within 60min after reperfusion

Ratio of electron donor to acceptor influences metabolic specialization and denitrification dynamics in Pseudomonas aeruginosa in a mixed carbon medium

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zhang, I. H., Mullen, S., Ciccarese, D., Dumit, D., Martocello, D. E., Toyofuku, M., Nomura, N., Smriga, S., & Babbin, A. R. Ratio of electron donor to acceptor influences metabolic specialization and denitrification dynamics in Pseudomonas aeruginosa in a mixed carbon medium. Frontiers in Microbiology, 12, (2021): 711073, https://doi.org/10.3389/fmicb.2021.711073.Denitrifying microbes sequentially reduce nitrate (NO3–) to nitrite (NO2–), NO, N2O, and N2 through enzymes encoded by nar, nir, nor, and nos. Some denitrifiers maintain the whole four-gene pathway, but others possess partial pathways. Partial denitrifiers may evolve through metabolic specialization whereas complete denitrifiers may adapt toward greater metabolic flexibility in nitrogen oxide (NOx–) utilization. Both exist within natural environments, but we lack an understanding of selective pressures driving the evolution toward each lifestyle. Here we investigate differences in growth rate, growth yield, denitrification dynamics, and the extent of intermediate metabolite accumulation under varying nutrient conditions between the model complete denitrifier Pseudomonas aeruginosa and a community of engineered specialists with deletions in the denitrification genes nar or nir. Our results in a mixed carbon medium indicate a growth rate vs. yield tradeoff between complete and partial denitrifiers, which varies with total nutrient availability and ratios of organic carbon to NOx–. We found that the cultures of both complete and partial denitrifiers accumulated nitrite and that the metabolic lifestyle coupled with nutrient conditions are responsible for the extent of nitrite accumulation.Funding for this work was provided by Simons Foundation award 622065 and an MIT Environmental Solutions Initiative seed grant to AB. Additional support was received by the MIT Ferry Fund

Biological responses according to the shape and size of carbon nanotubes in BEAS-2B and MESO-1 cells

This study aimed to investigate the influence of the shape and size of multi-walled carbon nanotubes (MWCNTs) and cup-stacked carbon nanotubes (CSCNTs) on biological responses in vitro. Three types of MWCNTs - VGCF (R)-X, VGCF (R)-S, and VGCF (R) (vapor grown carbon fibers; with diameters of 15, 80, and 150 nm, respectively) - and three CSCNTs of different lengths (CS-L, 20-80 mu m; CS-S, 0.5-20 mu m; and CS-M, of intermediate length) were tested. Human bronchial epithelial (BEAS-2B) and malignant pleural mesothelioma cells were exposed to the CNTs (1-50 mu g/mL), and cell viability, permeability, uptake, total reactive oxygen species/superoxide production, and intracellular acidity were measured. CSCNTs were less toxic than MWCNTs in both cell types over a 24-hour exposure period. The cytotoxicity of endocytosed MWCNTs varied according to cell type/size, while that of CSCNTs depended on tube length irrespective of cell type. CNT diameter and length influenced cell aggregation and injury extent. Intracellular acidity increased independently of lysosomal activity along with the number of vacuoles in BEAS-2B cells exposed for 24 hours to either CNT (concentration, 10 mu g/mL). However, total reactive oxygen species/superoxide generation did not contribute to cytotoxicity. The results demonstrate that CSCNTs could be suitable for biological applications and that CNT shape and size can have differential effects depending on cell type, which can be exploited in the development of highly specialized, biocompatible CNTs.ArticleINTERNATIONAL JOURNAL OF NANOMEDICINE. 9:1979-1990 (2014)journal articl