Proceedings of the Japan Academy. Series B, Physical and Biological Sciences最新文献

Red adzuki beans (Vigna angularis) are primarily used in producing sweet an-paste for use in Japanese confectionery, where the quality of the an-paste is evaluated based on its purple color. Catechinopyranocyanidins A and B (cpcA and cpcB) are seed coat pigments and might be responsible for the purple color of an-paste, thus, analyzing them in an-paste is crucial. However, no quantitative analyses of these compounds in an-paste have been reported. We examined extraction conditions for cpcA and cpcB from an-paste and established a quantitative analytical method. Additionally, we developed a pre-vacuum processing procedure for preparing purple an-paste. The more purple the an-paste was, the higher the content of cpcA and cpcB extracted from it. The purple color of an-paste originated from the catechinopyranocyanidins eluted from the seed coats upon boiling. Using the proposed procedure, we prepared more intensely purple wet sarashi-an compared with that generated via a conventional procedure.

Chloroplasts are photosynthetic organelles that evolved through the endosymbiosis between cyanobacteria-like symbionts and hosts. Many studies have attempted to isolate intact chloroplasts to analyze their morphological characteristics and photosynthetic activity. Although several studies introduced isolated chloroplasts into the cells of different species, their photosynthetic activities have not been confirmed. In this study, we isolated photosynthetically active chloroplasts from the primitive red alga Cyanidioschyzon merolae and incorporated them in cultured mammalian cells via co-cultivation. The incorporated chloroplasts retained their thylakoid structure in intracellular vesicles and were maintained in the cytoplasm, surrounded by the mitochondria near the nucleus. Moreover, the incorporated chloroplasts maintained electron transport activity of photosystem II in cultured mammalian cells for at least 2 days after the incorporation. Our top-down synthetic biology-based approach may serve as a foundation for creating artificially photosynthetic animal cells.

The tremendous tidal force that is linked to the supermassive black hole (SMBH) at the center of our galaxy is expected to strongly subdue star formation in its vicinity. Stars within 1'' from the SMBH thus likely formed further from the SMBH and migrated to their current positions. In this study, spectroscopic observations of the star S0-6/S10, one of the closest (projected distance from the SMBH of ≈0''.3) late-type stars were conducted. Using metal absorption lines in the spectra of S0-6, the radial velocity of S0-6 from 2014 to 2021 was measured, and a marginal acceleration was detected, which indicated that S0-6 is close to the SMBH. The S0-6 spectra were employed to determine its stellar parameters including temperature, chemical abundances ([M/H], [Fe/H], [α/Fe], [Ca/Fe], [Mg/Fe], [Ti/Fe]), and age. As suggested by the results of this study, S0-6 is very old (≳10 Gyr) and has an origin different from that of stars born in the central pc region.

In the late 1970s, crude interferon samples were found to exhibit anti-tumour activity. This discovery led to the interferon as a "magic drug" for cancer patients. Many groups, including those in Tokyo, Zürich, and San Francisco, attempted to identify human interferon cDNAs. Tadatsugu Taniguchi was the first to announce the cloning of human interferon-β cDNA in the December 1979 issue of Proc. Jpn. Acad. Ser. B. This was followed by the cloning of human interferon-α by a Zürich group and interferon-γ by a group in Genentech in San Francisco. Recombinant interferon proteins were produced on a large scale, and interferon-α was widely used to treat C-type hepatitis patients. The biological functions of interferons were quickly elucidated with the purified recombinant interferons. The molecular mechanisms underlying virus-induced interferon gene expression were also examined using cloned chromosomal genes. The background that led to interferon gene cloning and its impact on cytokine gene hunting is described herein.

Calcium ions (Ca²⁺) play critical roles in various biological phenomena. The free Ca²⁺ concentration in the cytoplasm of a resting cell is at the 10^-7 M level, whereas that outside the cell is 10^-3 M, creating a 10,000-fold gradient of Ca²⁺ concentrations across the cell membrane, separating the intracellular and extracellular solutions.^1),2) When a cell is activated by external stimuli, the intracellular Ca²⁺ concentration increases to levels of 10^-6-10^-5 M through Ca²⁺ entry from the extracellular solution via plasma membrane Ca²⁺ channels and/or Ca²⁺ release from intracellular stores. This transient increase in Ca²⁺ functions as an important signal mediated by Ca²⁺ sensors. Thus, Ca²⁺ signals are transmitted to intracellular loci such as distinct, localized targets of Ca²⁺ sensors. Among numerous Ca²⁺ sensors present in cells, calmodulin is a highly conserved and ubiquitous Ca²⁺ sensor.³⁾.

Magnetron production and use far exceed that of other microwave tubes due to their high operational efficiency, power efficiency, and cost-effectiveness in production. The magnetron was named by A. W. Hull; however, the device invented by Hull differs from the magnetron utilized as a microwave tube. The magnetron widely used today is based on the split-anode magnetron invented by K. Okabe. This overview introduces two papers published by Okabe in the Proceedings of the Imperial Academy and discusses the events that led to the discovery of the split-anode magnetron. In addition, the operation mechanisms of magnetrons are explained.

Carbon nanotubes are a telecom band emitter compatible with silicon photonics, and when coupled to microcavities, they present opportunities for exploiting quantum electrodynamical effects. Microdisk resonators demonstrate the feasibility of integration into the silicon platform. Efficient coupling is achieved using photonic crystal air-mode nanobeam cavities. The molecular screening effect on nanotube emission allows for spectral tuning of the coupling. The Purcell effect of the coupled cavity-exciton system reveals near-unity radiative quantum efficiencies of the excitons in carbon nanotubes.

Flavonoids, such as quercetin and kaempferol, and their glycosides, are widely distributed in vegetables and fruits. Sugimura, T. et al. investigated the mutagenicity of flavone derivatives, and found that quercetin and kaempferol showed high mutagenic activities in Salmonella typhimurium TA98 with S9 mix, comparable to that of the typical carcinogen, benzo[a]pyrene. These novel findings were published in Proc. Jpn. Acad. Ser. B 53, 194-197, 1977. Other research groups also reported the mutagenic properties of flavone derivatives in S. typhimurium strains. These observations led to the commencement of long-term animal carcinogenesis experiments involving quercetin. A USA-Turkey joint study reported that feeding rats with 0.1% quercetin in the diet produced carcinomas. However, Japanese scientists showed no carcinogenicity with quercetin in rats, mice, or hamsters, even at 10% in the diet. NTP Technical Report on the Toxicology and Carcinogenesis Studies of Quercetin in F344/N Rats concluded that there was no evidence of its carcinogenic activity. Therefore, the potential risk of quercetin in human cancers is likely to be negligible. These flavonoid issues provided a warning regarding the simplistic understanding that mutagens are carcinogens, and microbial tests alone are inadequate for safety assessment; therefore, and a battery of tests for genotoxicity is recommended. Thus, the informative report in 1977 made significant contributions to initiating and promoting genotoxicity studies of flavonoids.