Design and Development of Prelude, Satellite for Seismic Precedence Detection and Verification Using VLF Radio Waves for Navigation Obtained in Orbit

In this study, we analyzed the ionospheric anomaly in the D region, which precedes the occurrence of earthquakes, by focusing on the VLF radio wave for navigation, which is used for military communication, among the observation data of the earth observation satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions). We analyzed the ionospheric anomaly in the D region that occurs prior to an earthquake. Next, based on the results, we propose the design of a 6U nano-satellite dedicated to the detection of earthquake precursory phenomena using navigational VLF radio waves: Prelude (Precursory electric field observation CubeSat demonstrator). The design of Prelude (Precursory electric field observation CubeSat demonstrator) is proposed. In a previous study, the authors of Němec, Kamogawa et al. attributed this decrease in intensity to an increase in electron density in the D region. Kamogawa et al. attributed this decrease to an increase in electron density in the D region. Based on these results, our proposed satellite mission will be to observe ionospheric anomalies in the D-region that precede earthquakes for the purpose of short-term earthquake prediction in the future. Němec et al. and Kamogawa et al. have studied the variation of electron density in the D region by analyzing the radio waves generated by lightning. However, the accuracy of this method is limited for the following three reasons: 1) the frequency of lightning is different depending on the season, 2) the frequency range of lightning is wider than that of thunderstorms, and 3) there are dispersion characteristics of radio waves due to ionospheric plasma. Therefore, in this study, we focused on the variation of electron density in the D region by focusing on the VLF charged wave for navigation, which has a constant frequency, continuous transmission, and temporal and spatial continuity. As a case study analysis, we confirmed the validity of the analysis of navigational VLF waves by focusing on the earthquake in southern Sumatra. The results show that the navigational VLF signal intensity decreases significantly before the earthquake compared to the trajectories in the comparison counties. This suggests that the effects of ionospheric fluctuations shown by Němec In addition, we found that the VLF radio wave strength of Prelude was significantly reduced before the earthquake. Furthermore, this study showed the effectiveness of navigational VLF radio waves as a new analysis target for Prelude\u27s mission analysis. Therefore, we considered that there is a room to introduce a flexible system for the design and development of the science mission during the design and development of this satellite by using Systems Modeling

Cholesterol accumulation in ovarian follicles causes ovulation defects in Abca1a⁻/⁻ Japanese medaka (Oryzias latipes)

ATP-binding cassette A1 (ABCA1) is a membrane protein, which exports excess cellular cholesterol to generate HDL to reduce the risk of the onset of cardiovascular diseases (CVD). In addition, ABCA1 exerts pleiotropic effects on such as inflammation, tissue repair, and cell proliferation and migration. In this study, we explored the novel physiological roles of ABCA1 using Japanese medaka (Oryzias latipes), a small teleost fish. Three Abca1 genes were found in the medaka genome. ABCA1A and ABCA1C exported cholesterol to generate nascent HDL as human ABCA1 when expressed in HEK293 cells. To investigate their physiological roles, each Abca1-deficient fish was generated using the CRISPR-Cas9 system. Abca1a−/− female medaka was found to be infertile, while Abca1b−/− and Abca1c−/− female medaka were fertile. In vitro ovarian follicle culture suggested that Abca1a deficiency causes ovulation defects. In the ovary, ABCA1A was expressed in theca cells, an outermost layer of the ovarian follicle. Total cholesterol content of Abca1a−/− ovary was significantly higher than that of the wild-type, while estrogen and progestin contents were compatible with those of the wild-type. Furthermore, cholesterol loading to the wild-type follicles caused ovulation defects. These results suggest that ABCA1A in theca cells regulates cholesterol content in the ovarian follicles and its deficiency inhibits successful ovulation through cholesterol accumulation in the ovarian follicle

In vivo FRET analyses reveal a role of ATP hydrolysis–associated conformational changes in human P-glycoprotein

P-glycoprotein (P-gp; also known as MDR1 or ABCB1) is an ATP-driven multidrug transporter that extrudes various hydrophobic toxic compounds to the extracellular space. P-gp consists of two transmembrane domains (TMDs) that form the substrate translocation pathway and two nucleotide-binding domains (NBDs) that bind and hydrolyze ATP. At least two P-gp states are required for transport. In the inward-facing (pre-drug transport) conformation, the two NBDs are separated, and the two TMDs are open to the intracellular side; in the outward-facing (post-drug transport) conformation, the NBDs are dimerized, and the TMDs are slightly open to the extracellular side. ATP binding and hydrolysis cause conformational changes between the inward-facing and the outward-facing conformations, and these changes help translocate substrates across the membrane. However, how ATP hydrolysis is coupled to these conformational changes remains unclear. In this study, we used a new FRET sensor that detects conformational changes in P-gp to investigate the role of ATP binding and hydrolysis during the conformational changes of human P-gp in living HEK293 cells. We show that ATP binding causes the conformational change to the outward-facing state and that ATP hydrolysis and subsequent release of γ-phosphate from both NBDs allow the outward-facing state to return to the original inward-facing state. The findings of our study underscore the utility of using FRET analysis in living cells to elucidate the function of membrane proteins such as multidrug transporters

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