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Keigo Enya 한국천문학회 2017 天文學論叢 Vol.32 No.1
This paper reviews the legacy of the SPCIA Coronagraph Instrument(SCI) of which the primary scientific objective is the characterizationof Jovian exoplanets by coronagraphic spectroscopy in the infrared. Studies on binary shaped pupil mask coronagraphs are described. Cryogenic active optics is discussed as another key technology. Then approaches to observing habitable zones in exoplanetary systemswith a passively-cooled space infrared telescope are discussed. The SCI was dropped in a drastic change of the SPICA mission. However, its legacy is useful for space-borne infrared telescopesdedicated for use in exoplanetary science in the future,especially for studies of biomarkers.
WIDEBAND SPECTRAL DISPERSER MADE OF ZnS FOR EXOPLANET CHARACTERIZATION USING SPACE-BORNE TELESCOPES
Keigo Enya,Naofumi Fujishiro 한국천문학회 2017 天文學論叢 Vol.32 No.1
We present the developmentof a spectral dispersion devicefor wideband spectroscopy for which the primary scientificobjective is the characterization of transiting exoplanets. The principle of the disperser is simple: a grating isfabricated on the surface of a prism. The direction of the spectral dispersion power of the prismis crossed with the grating. Thus, the prism separates the spectrum into individualorders while the grating produces a spectrum for each order. In this work, ZnS was selected as the materialfor the cross disperser, which was designed to coverthe wavelength region, λ = 0.6 -13 μm,with a spectral resolving power, R ≥ 50. A disperser was fabricated, and an evaluationof its surface was conducted. Two spectrometer designs, one adopting ZnS(λ = 0.6 -13 μm, R ≥ 300)and the other adopting CdZnTe( λ = 1 -23 μm, R ≥ 250), are presented. The spectrometers, each of which has no moving mechanical parts,consist simply of a disperser, a focusing mirror, and a detector.
LABORATORY EXPERIMENTS OF OFF-AXIS MIRROR OPTICS OF ALUMINUM FOR SPACE INFRARED MISSIONS
Shinji Oseki,SHINKI OYABU,DAISUKE ISHIHARA,Keigo Enya,Kanae Haze,Takayuki Kotani,HIDEHIRO KANEDA,Miho Nishiyama,Lyu Abe,Tomoyasu Yamamuro 한국천문학회 2017 天文學論叢 Vol.32 No.1
We report our research on aluminum mirror optics for future infrared astronomical satellites. For space infrared missions, cooling the whole instrument is crucial to suppress the infrared background and detector noise. In this aspect, aluminum is appropriate for cryogenic optics, because the same material can be used for the whole structure of the instrument including optical components thanks to its excellent machinability, which helps to mitigate optical misalignment at low temperatures. We have fabricated aluminum mirrors with ultra-precision machining and measured the wave front errors (WFEs) of the mirrors with a Fizeau interferometer. Based on the power spectral densities of the WFEs, we confirmed that the surface accuracy of all the mirrors satisfied the requirements for the SPICA Coronagraph Instrument. We then integrated the mirrors into an optical system, and examined the image quality of the system with an optical laser. As a result, the total WFE is estimated to be 33 nm (rms) from the Strehl ratio. This is consistent with the WFEs estimated from the measurement of the individual mirrors.
Kaneko Hiroaki,Ishiwata Shin-ichi,Takamura-Enya Takeji 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.4
Aquatic organisms frequently exhibit clear genetic structures over their distribution ranges. In a previous study, we showed that the mayfly Ecdyonurus yoshidae Takahashi also showed genetic delimitations in the Japanese archipelago. In this paper, we studied the dispersal and migration of this species using the fine-scale genetic structure and historical demographic dynamics in the Sagami River system using the DNA barcoding region mitochondrial cytochrome c oxidase subunit I gene sequence (COI). We detected two major haplogroups con structed from 44 distinct haplotypes in 226 specimens collected from 24 sampling sites. From the highest altitude of 530 m to the lowest of 7 m, the dominant haplotype was widespread throughout the rivers and the six tributaries and even spread to isolated microhabitats upstream. We did not observe genetic differentiation among the six tributaries and 24 sampling sites. Consequently, we estimated that the population occurring in the entire river system is maintained as a meta-population by suitable small-scale habitats. We found that E. yoshidae might be capable of crossing areas with unsuitable habitats, such as gorges and rapid streams. Furthermore, one haplogroup experienced population expansion—which affected the genetic structure across the Sagami River system—and another haplogroup might have migrated from an adjacent catchment.
Yagi, kashi,Fujikawa, Yoshihiro,Sawai, Tomoko,Takamura-Enya, Takeji,Ito-Harashima, Sayoko,Kawanishi, Masanobu Korean Society of ToxicologyKorea Environmental Mu 2017 Toxicological Research Vol.33 No.4
Aryl hydrocarbons such as 3-nitrobenzanthrone (NBA), 4-aminobiphenyl (ABP), acetylaminofluorene (AAF), benzo(a)pyrene (BaP), and 1-nitropyrene (NP) form bulky DNA adducts when absorbed by mammalian cells. These chemicals are metabolically activated to reactive forms in mammalian cells and preferentially get attached covalently to the $N^2$ or C8 positions of guanine or the $N^6$ position of adenine. The proportion of $N^2$ and C8 guanine adducts in DNA differs among chemicals. Although these adducts block DNA replication, cells have a mechanism allowing to continue replication by bypassing these adducts: translesion DNA synthesis (TLS). TLS is performed by translesion DNA polymerases-Pol ${\eta}$, ${\kappa}$, ${\iota}$, and ${\zeta}$ and Rev1-in an error-free or error-prone manner. Regarding the NBA adducts, namely, 2-(2'-deoxyguanosin-$N^2$-yl)-3-aminobenzanthrone (dG-$N^2$-ABA) and N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone (dG-C8-ABA), dG-$N^2$-ABA is produced more often than dG-C8-ABA, whereas dG-C8-ABA blocks DNA replication more strongly than dG-$N^2$-ABA. dG-$N^2$-ABA allows for a less error-prone bypass than dG-C8-ABA does. Pol ${\eta}$ and ${\kappa}$ are stronger contributors to TLS over dG-C8-ABA, and Pol ${\kappa}$ bypasses dG-C8-ABA in an error-prone manner. TLS efficiency and error-proneness are affected by the sequences surrounding the adduct, as demonstrated in our previous study on an ABP adduct, N-(2'-deoxyguanosine-8-yl)-4-aminobiphenyl (dG-C8-ABP). Elucidation of the general mechanisms determining efficiency, error-proneness, and the polymerases involved in TLS over various adducts is the next step in the research on TLS. These TLS studies will clarify the mechanisms underlying aryl hydrocarbon mutagenesis and carcinogenesis in more detail.
Takashi Yagi,Yoshihiro Fujikawa,Tomoko Sawai,Takeji Takamura-Enya,Sayoko Ito-Harashima,Masanobu Kawanishi 한국독성학회 2017 Toxicological Research Vol.33 No.4
Aryl hydrocarbons such as 3-nitrobenzanthrone (NBA), 4-aminobiphenyl (ABP), acetylaminofluorene (AAF), benzo(a)pyrene (BaP), and 1-nitropyrene (NP) form bulky DNA adducts when absorbed by mammalian cells. These chemicals are metabolically activated to reactive forms in mammalian cells and preferentially get attached covalently to the N² or C8 positions of guanine or the N6 position of adenine. The proportion of N² and C8 guanine adducts in DNA differs among chemicals. Although these adducts block DNA replication, cells have a mechanism allowing to continue replication by bypassing these adducts: translesion DNA synthesis (TLS). TLS is performed by translesion DNA polymerases—Pol η, κ, ι, and ζ and Rev1—in an error-free or error-prone manner. Regarding the NBA adducts, namely, 2-(2"-deoxyguanosin-N²-yl)-3-aminobenzanthrone (dG-N²-ABA) and N-(2"-deoxyguanosin-8-yl)-3-aminobenzanthrone (dG-C8-ABA), dG-N²-ABA is produced more often than dG-C8-ABA, whereas dG-C8-ABA blocks DNA replication more strongly than dG-N²-ABA. dG-N2-ABA allows for a less error-prone bypass than dG-C8-ABA does. Pol η and κ are stronger contributors to TLS over dG-C8-ABA, and Pol κ bypasses dG-C8-ABA in an error-prone manner. TLS efficiency and error-proneness are affected by the sequences surrounding the adduct, as demonstrated in our previous study on an ABP adduct, N-(2"-deoxyguanosine-8-yl)-4-aminobiphenyl (dG-C8-ABP). Elucidation of the general mechanisms determining efficiency, errorproneness, and the polymerases involved in TLS over various adducts is the next step in the research on TLS. These TLS studies will clarify the mechanisms underlying aryl hydrocarbon mutagenesis and carcinogenesis in more detail.
Kaneko Hiroaki,Ishiwata Shin‐ichi,Bae Yeon Jae,Takamura‐Enya Takeji 한국곤충학회 2021 Entomological Research Vol.51 No.5
Because of their early divergence in insect evolution, unique aquatic larval stage, and low dispersal ability, many mayfly species exhibit genetic structures that accurately reflect geological history and paleoclimatic changes. The present study investigated the genetic characteristics of Ecdyonurus yoshidae Takahashi (Ephemeroptera: Heptageniidae), a mayfly that inhabits a variety of freshwater habitats in Japan. Mitochondrial cytochrome c oxidase subunit I (COI) and 16S ribosomal RNA (16S rRNA) gene sequences were generated from 209 mayfly specimens that were collected from 109 sites in Japan. A total of 145 haplotypes were detected, and nine of the lineages exhibited geographical regionality, with one lineage being endemic to Lake Biwa. The haplotype network was “bottleneck type” and included both star-like structures and missing (or unobserved) haplotypes. Together, the haplotype network and FST values indicated that the Fukuejima Island group (Clade I) was genetically distinct from groups on the island of Kyushu, which is separated from Fukuejima Island by the Gotonada Sea. The common ancestor of E. yoshidae lineages in Japan was estimated to have diverged 1.14 mega-annum (Ma) (95% highest posterior density interval, 0.55–1.78 Ma), and more regional genetic diversities were generated during the Middle to Late Pleistocene. Genetically distinct lineages of eastern and western Japan were separated by the Kinki Triangle region in central Japan. The genetic diversity of the habitat generalist E. yoshidae increased during the Middle and Late Pleistocene, when crustal movement and climate change in the Japanese archipelago occurred simultaneously.