Noda Institute for Scientific Research

Aspergillus fumigatus causes a range of human and animal diseases collectively known as aspergillosis. A. fumigatus possesses and expresses a range of genetic determinants of virulence, which facilitate colonisation and disease progression, including the secretion of mycotoxins. Gliotoxin (GT) is the best studied A. fumigatus mycotoxin with a wide range of known toxic effects that impair human immune cell function. GT is also highly toxic to A. fumigatus and this fungus has evolved self-protection mechanisms that include (i) the GT efflux pump GliA, (ii) the GT neutralising enzyme GliT, and (iii) the negative regulation of GT biosynthesis by the bis-thiomethyltransferase GtmA. The transcription factor (TF) RglT is the main regulator of GliT and this GT protection mechanism also occurs in the non-GT producing fungus A. nidulans. However, the A. nidulans genome does not encode GtmA and GliA. This work aimed at analysing the transcriptional response to exogenous GT in A. fumigatus and A. nidulans, two distantly related Aspergillus species, and to identify additional components required for GT protection. RNA-sequencing shows a highly different transcriptional response to exogenous GT with the RglT-dependent regulon also significantly differing between A. fumigatus and A. nidulans. However, we were able to observe homologs whose expression pattern was similar in both species (43 RglT-independent and 11 RglT-dependent). Based on this approach, we identified a novel RglT-dependent methyltranferase, MtrA, involved in GT protection. Taking into consideration the occurrence of RglT-independent modulated genes, we screened an A. fumigatus deletion library of 484 transcription factors (TFs) for sensitivity to GT and identified 15 TFs important for GT self-protection. Of these, the TF KojR, which is essential for kojic acid biosynthesis in Aspergillus oryzae, was also essential for virulence and GT biosynthesis in A. fumigatus, and for GT protection in A. fumigatus, A. nidulans, and A. oryzae. KojR regulates rglT, gliT, gliJ expression and sulfur metabolism in Aspergillus species. Together, this study identified conserved components required for GT protection in Aspergillus species.

We propose a surrogate-assisted reference vector adaptation (SRVA) method to\nsolve expensive multi- and many-objective optimization problems with various\nPareto front shapes. SRVA is coupled with a multi-objective Bayesian\noptimization (MBO) algorithm using reference vectors for scalarization of\nobjective functions. The Kriging surrogate models for MBO is used to estimate\nthe Pareto front shape and generate adaptive reference vectors uniformly\ndistributed on the estimated Pareto front. We combine SRVA with expected\nimprovement of penalty-based boundary intersection as an infill criterion for\nMBO. The proposed algorithm is compared with two other MBO algorithms by\napplying them to benchmark problems with various Pareto front shapes.\nExperimental results show that the proposed algorithm outperforms the other two\nin the problems whose objective functions are reasonably approximated by the\nKriging models. SRVA improves diversity of non-dominated solutions for these\nproblems with continuous, discontinuous, and degenerated Pareto fronts.\nBesides, the proposed algorithm obtains much better solutions from early stages\nof optimization especially in many-objective problems.\n

Ethical considerations are more stringent in pediatric clinical research than in research targeting adults. However, in Japan, clear guidelines have yet to be presented on the necessary ethical considerations for clinical research involving children. The "Principles of Ethical Consideration Required for Clinical Research Involving Children" provide guiding principles for ethical considerations and the essential ways of thinking that all involved in clinical research on children need to understand in advance.

Recent development of stimulated Raman scattering (SRS) microscopy allows for label-free biological imaging with chemical specificity based on molecular-vibrational signatures. In particular, hyperspectral SRS imaging can acquire a molecular-vibrational spectrum at each pixel, allowing us not only to investigate the spectral difference of various biological molecules but also to discriminate different constituents based on their spectral difference. However, the number of constituents discriminated in previous label-free SRS imaging was limited to four because of the subtleness of spectral difference. Here, we report hyperspectral SRS imaging of plant tissues including leaves of Camellia japonica, roots of Arabidopsis thaliana, and thalli of a liverwort Marchantia polymorpha L. We show that SRS can discriminate as many as six components in Marchantia polymorpha L. without labeling. Our results demonstrate the effectiveness of hyperspectral SRS imaging as a tool for label-free multicolour imaging analysis of various biomolecules in plant tissues.

In–Fe mixed oxide with the bixbyite-type structure functions as a new oxygen evolution photocatalyst for visible light driven Z-scheme water splitting.

Vascular endothelial cells cover the luminal surface of blood vessels in a monolayer. Proliferation of these cells is crucial for the repair of damaged endothelial monolayers. In the present study, we identified a zinc complex, Zn(ii)2,9-dimethyl-1,10-phenanthroline (Zn-12), that stimulates the proliferation of bovine aortic endothelial cells in a culture system. No such stimulatory activity was observed for the ligand alone or in combination with other metals; however, the ligand combined with iron weakly stimulated the proliferation, as evidenced by the [3H]thymidine incorporation assay. Inorganic zinc weakly but significantly stimulated proliferation, and intracellular accumulation of zinc was similar between inorganic zinc and Zn-12 treatment, suggesting that the mechanisms by which Zn-12 stimulates vascular endothelial cell proliferation contain processes that differ from those by which inorganic zinc stimulates proliferation. Although expression of endogenous fibroblast growth factor-2 (FGF-2) and its receptor FGFR-1 was unchanged by Zn-12, both siRNA-mediated knockdown of FGF-2 and FGFR inhibition partly but significantly suppressed the stimulation of vascular endothelial cell proliferation by Zn-12, indicating that the zinc complex activates the FGF-2 pathway to stimulate proliferation. Phosphorylation of ERK1/2 and MAPKs was induced by Zn-12, and PD98059, a MEK1 inhibitor, significantly suppressed the stimulatory effect of Zn-12 on vascular endothelial cell proliferation. Therefore, it is suggested that Zn-12 activates the FGF-2 pathway via activation of ERK1/2 signaling to stimulate vascular endothelial cell proliferation, although FGF-2-independent mechanisms are also involved in the stimulation. Zn-12 and related compounds may be promising molecular probes to analyze biological systems of vascular endothelial cells.

Phosphorothioate (PS) modification, where a non-bridging oxygen atom in a phosphodiester linkage is replaced by a sulfur atom, is widely used to improve the properties of nucleic acid drugs. Each PS linkage can be found in two stereoisomers, Rp and Sp. Since one non-bridging oxygen or sulfur atom in Sp-PS or Rp-PS, respectively, is located close to the C-5 substituent of uracil in a DNA/RNA hybrid duplex, the combination of the stereochemistry of the PS linkages and the type of the C-5 modification of uracil bases is expected to affect the properties of the hybrid duplexes. Herein, DNA oligomers containing both stereopure phosphorohioate linkages and C-5 modified deoxyuridine derivatives were synthesized. The thermodynamic stability of the DNA/RNA and DNA/DNA duplexes and RNase H activity of the DNA/RNA duplexes were evaluated. The combination of 5-propynyluracil and (Rp)-PS linkages in a DNA strand could significantly increase the thermal stability of a DNA/RNA hybrid duplex without reducing its RNase H activity.

We recently developed an Aspergillus oryzae strain in which malonyl-coenzyme A (CoA) supply is strengthened by the deletion of snfA and SCAP as an efficient host to produce a plant polyketide, curcumin. Here, we examined the effectiveness of this strain in producing another polyketide, atrochrysone carboxylic acid (ACA), which is synthesized from eight molecules of malonyl-CoA using an iterative type I polyketide synthase, ACA synthase (ACAS), and atrochrysone carboxyl ACP thioesterase (ACTE) in Aspergillus terreus. When ACAS and ACTE were introduced, the A. oryzae ΔsnfAΔSCAP strain produced approximately four times more ACA-related polyketides than did the control strain expressing both genes. This result further demonstrated the availability of the A. oryzae ΔsnfAΔSCAP strain for heterologous polyketide production.