Biosynthetic regulation of phytochelatins, heavy metal-binding peptides

Phytochelatins (PCs) are heavy metal-binding peptides that play important roles in the detoxification of toxic heavy metals and the regulation of intracellular concentrations of essential metals in eukaryotes, including higher plants, fungi, and microalgae. Recently, PC synthase genes in higher plants and fission yeast have been identified and characterized, enabling molecular biological studies to unravel the mechanisms underlying PC synthesis. Moreover, recent routine database searches have unexpectedly identified genes that are similar to plant PC synthase genes in the genomes of worms and some prokaryotes. In this review, we introduce these recent advances in our understanding of the molecular mechanisms for PC biosynthesis and functions in order to supply basic information about the unique and attractive peptides applicable to various fields.     

DNA and chemical analyses of commercial fly agaric-related products

Since June 6, 2002, psilocin and psilocybin-containing fungi (commonly called "magic mushrooms") have been regulated by the Narcotics and Psychotropics Control Law in Japan. However, various fly agaric-related products are now entering the Japanese market via the internet. In this study, fly agaric-related products available in this way were investigated for raw materials by DNA analysis and for additives by chemical analysis. Nucleotide sequence analysis of the mitochondrial 12S rDNA region suggested that these fly agaric-related products originate from A. muscaria or A. muscaria var. persicina. Furthermore, they were classified into three strains based on the ITS2-LSU nucleotide sequence. Harmine derivatives and/or tryptamine derivatives were detected in some of these products by LC/MS analysis. In accordance with this, the matK gene of Peganum harmala was found in all of the harmine derivative-containing samples.     

Ultrastructural immunocytochemistry of the adenohypophysis in the rat: A review

Immunocytochemistry has made great strides in the morphology of endocrine glands, especially the adenohypophysis, because the localization of hormones can be clearly demonstrated by this method in the microscopic preparations both for light and electron microscopy. In the adenohypophysis, electron microscopic immunocytochemistry is useful for identifying the producer cell of each hormone. The second contribution is its application to the cell biology of secretion mechanisms. The pituitary hormones, their precursors, derivatives, and fragments were artificially synthesized and their antibodies were produced. Using these antibodies the intracellular sites of synthesis, condensation, processing, and sorting were studied under the electron microscope. The ultrastructure of each cell organelle and its alteration due to the changing function was studied. It was proved that the intracisternal granules in the thyroidectomy cells contain thyroid-stimulating hormone (TSH). The trans-Golgi network or GERL contains a peculiar supporting structure, intracisternal skeleton. Transport of secretory granules may be performed in relation to the microtubules, actin, and some related substances. The most frequently observed mode of hormone release in the adenohypophysis is exocytosis. Sometimes multigranular exocytosis occurs. Vesiculation of membrane around the secretory granules often occur inward or outward. The inward vesiculation forms pinocytotic vesicles, through which the membrane material may be retrieved. The outward vesiculation forms vesicle-like fragments of cytoplasm being discarded to the extracellular space. By these mechanisms the surface area of the cell is maintained constantly.     

Superconducting Coupling Nature at Grain Boundaries in Bi2Sr2CaCu2Ox Glass-Ceramics

Superconducting coupling nature at grain boundaries in Bi₂Sr₂CaCu₂O _x glass-ceramics consisting mainly of the low- T _c phase was first examined by measuring superconducting properties and temperature or ac field dependence of ac complex susceptibility. It was found from the ac loss peaks that superconducting coupling at grain boundaries was basically characterized by three types of weak links. The weak-link behaviors at grain boundaries depended strongly on cooling conditions after annealing and annealing time and temperature. Particularly, it was found that the weak links at grain boundaries were improved by prolonged annealing at 840°C. The furnace-cooled glass-ceramics obtained by annealing at 820° or 840°C for about 200 h exhibited a critical transport current density (77 K, zero magnetic field) of about 200 A/cm².     

Oxidative Transformations of 3,4-Dihydroxyphenylacetaldehyde Generate Potential Reactive Intermediates as Causative Agents for Its Neurotoxicity

Neurogenerative diseases, such as Parkinson’s disease, are associated, not only with the selective loss of dopamine (DA), but also with the accumulation of reactive catechol-aldehyde, 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is formed as the immediate oxidation product of cytoplasmic DA by monoamine oxidase. DOPAL is well known to exhibit toxic effects on neuronal cells. Both catecholic and aldehyde groups seem to be associated with the neurotoxicity of DOPAL. However, the exact cause of toxicity caused by this compound remains unknown. Since the reactivity of DOPAL could be attributed to its immediate oxidation product, DOPAL-quinone, we examined the potential reactions of this toxic metabolite. The oxidation of DOPAL by mushroom tyrosinase at pH 5.3 produced conventional DOPAL-quinone, but oxidation at pH 7.4 produced the tautomeric quinone-methide, which gave rise to 3,4-dihydroxyphenylglycolaldehyde and 3,4-dihydroxybenzaldehyde as products through a series of reactions. When the oxidation reaction was performed in the presence of ascorbic acid, two additional products were detected, which were tentatively identified as the cyclized products, 5,6-dihydroxybenzofuran and 3,5,6-trihydroxybenzofuran. Physiological concentrations of Cu(II) ions could also cause the oxidation of DOPAL to DOPAL-quinone. DOPAL-quinone exhibited reactivity towards the cysteine residues of serum albumin. DOPAL-oligomer, the oxidation product of DOPAL, exhibited pro-oxidant activity oxidizing GSH to GSSG and producing hydrogen peroxide. These results indicate that DOPAL-quinone generates several toxic compounds that could augment the neurotoxicity of DOPAL.     

CRISPR Screen Contributes to Novel Target Discovery in Prostate Cancer

Prostate cancer (PCa) is one of the common malignancies in male adults. Recent advances in omics technology, especially in next-generation sequencing, have increased the opportunity to identify genes that correlate with cancer diseases, including PCa. In addition, a genetic screen based on CRISPR/Cas9 technology has elucidated the mechanisms of cancer progression and drug resistance, which in turn has enabled the discovery of new targets as potential genes for new therapeutic targets. In the era of precision medicine, such knowledge is crucial for clinicians in their decision-making regarding patient treatment. In this review, we focus on how CRISPR screen for PCa performed to date has contributed to the identification of biologically critical and clinically relevant target genes.     

Ethanol oxidation reaction activity of highly dispersed Pt/SnO2 double nanoparticles on carbon black

Highly dispersed Pt and SnO₂ double nanoparticles containing different Pt/Sn ratios (denoted as Pt/SnO₂/CB) were prepared on carbon black (CB) by the modified Bönnemann method. The average size of Pt and SnO₂ nanoparticles was 3.1 ± 0.5 nm and 2.5 ± 0.3 nm, respectively, in Pt/SnO₂(3:1)/CB, 3.0 ± 0.5 nm and 2.6 ± 0.3 nm, respectively, in Pt/SnO₂(1:1)/CB, and 2.8 ± 0.5 nm and 2.5 ± 0.3 nm, respectively, in Pt/SnO₂(1:3)/CB. The Pt/SnO₂(3:1)/CB electrode showed the highest specific activity and lowest overpotential for ethanol oxidation reaction (EOR), and was superior to a Pt/CB electrode. Current density for EOR at 0.40 and 0.60 V vs. reversible hydrogen electrode for the Pt/SnO₂(3:1)/CB electrode decayed more slowly than that for the Pt/CB electrode because of a synergistic effect between Pt and SnO₂ nanoparticles. The predominant reaction product was acetic acid, and its current efficiency was about 70%, while that for CO₂ production was about 30%.     

Analysis of heat-treated graphite oxide by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) is among the most powerful methods to determine the surface chemical properties of carbon materials. Because heat-treated graphite oxide includes various defects, analyses of the structure by XPS help us understand the structures of various carbon materials. Thus, XPS spectra of graphene-related materials containing various functional groups and other defects on edges and in the basal plane were simulated and full width at half maximums (FWHMs) and peak shifts were obtained by density functional theory calculation. Shifts of whole C1s spectra were influenced by the electron-withdrawing functional groups such as C=O-containing functional groups. FWHMs of the main peak of C1s spectra were influenced by mainly electron-withdrawing functional groups in addition to defects such as vacancy, pentagons, and heptagons. Analyses using only XPS provide us limited information, even though the peak tops and FHWMs of simulated XPS spectra are used for assignment. Combination use of peak shifts and FWHMs of XPS spectra, infrared spectroscopy, and density functional theory calculation provided more reliable assignments of defects including oxygen-containing functional groups of carbon materials than commonly used methods using only peak shifts of XPS spectra.     

MPCP based active optical access network with PLZT high-speed optical switch

An active optical access network architecture with our newly developed PLZT ((Pb,La)(Zr,Ti)O₃) high-speed optical switch is introduced, with a view to realizing the next-generation high capacity scalable access network. This system is developed based on the latest IEEE standard of PON (10G-EPON; IEEE802.3av) in consideration of the coordination with future high capacity PON. PLZT high-speed optical switches are able to switch an optical signal at nano-second speed (<5-10 ns). Generally, the merits of using optical switches are increasing the number of subscribers and transmission distance easily, preventing malicious ONUs from interfacing with the communication between OLT and the other ONUs, realizing fast fiber and OLT protection/restoration and providing various services by controlling optical switches dynamically. This paper focuses on two key technologies; a PLZT optical switch and a new discovery process for active optical access network based on MPCP defined at IEEE802.3. A major challenge in designing active optical access network is supporting the discovery process of MPCP because it does not offer broadcast transmission unlike the regular PON. We propose here a new discovery process; it has been tested successfully in an implementation of our proposed system.