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461.
Ko Kaneko Utako Nakaoka Mikako Tanaka Naotoshi Yoshida Hiroshi Mitsuhashi 《Phytochemistry》1981,20(1):157-160
After acid hydrolysis of a glycosidic fraction from the aerial parts of Fritillaria camtschatcensis, in addition to solanidine, tomatidenol, and solasodine, two N-methyl-22,26-epiminocholestenes, hapepunine and anrakorinine, were isolated and their structures elucidated by physical and chemical methods. 相似文献
462.
Hidetoshi Goto Masanao Sudoh Keiko Kawamoto Hiroshi Sugimoto Shohei Inoue 《Chirality》2012,24(10):867-878
Designs and syntheses of isocyanurates ( 1–3 ) are described on the basis of a novel concept that two enantiotopic faces of Cs‐symmetric, prochiral planar molecules are differentiated with a location of groups at the top or bottom of the planar skeleton using a rigid linker. Such isocyanurates are atropisomeric. The planar‐chiral structures of 1 and 2 anti (anti‐conformer of 2 ) were confirmed by single‐crystal X‐ray analyses, and the space groups were P1 (for 1 ) and P21/c (for 2 anti), resulting that the crystals were racemates. Optical resolutions of 1–3 were successfully accomplished by using chiral high‐performance liquid chromatography technique in combination with circular dichroism, absorption, and nuclear magnetic resonance spectroscopies and mass spectrometry. Furthermore, the rotational barriers (ΔG?s) related to isomerizations of 1–3 were estimated to be 27.2 (for 1 at 50 °C), 27.6 (for 2 anti at 50 °C), and 40.6 (for 3 syn at 150 °C) kcal/mol. The ΔG?s of 2 and 3 were higher than that of 1 and, in particular, that of 3 was highest among them. This result indicates that an introduction of bulky substituents and an intramolecular bridging are effective for inhibitions of the isomerizations. Chirality 00:000–000, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
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H. Tokushima K. -I. Okamoto Y. Nakaoka I. Miwa 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,175(6):767-772
Paramecium bursaria shows a circadian rhythm of photoaccumulation: photoaccumulation is stronger during the day than at night. We obtained five strains of P. bursaria having different circadian periods under continuous light conditions, ranging from 20.9 to 27.9 h. Various physiological activities were compared in the cells of these strains. The periods of contractile vacuole contraction were in the range 10–15 s, which was almost proportional to the periods of the circadian rhythm in each strain. Swimming velocities were inversely proportional to the circadian period; i.e. swimming velocities were high in strains whose circadian periods were short. Resting membrane potential was more depolarized in strains with longer circadian periods. Finally, the membrane resistance of the resting state was reduced in proportion to the increase of the circadian period. Such correlation between the cellular properties and the circadian period suggests that the circadian clock mechanism is associated with various physiological activities of the cell. 相似文献
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467.
Tetsuo Takigawa Michiaki Tominaga Kenji Mori Masanao Matsui 《Bioscience, biotechnology, and biochemistry》2013,77(7):1591-1594
Methyl (2E,6E)-10,11-epithio-3,7,11-trimethyl-2,6-dodecadienoate (the thiirane analog of JH III), 6,7-epithiogeranyl 4-methylphenyl ether and 6,7-epithiogeranyl 3,4-methylenedioxyphenyl ether were synthesized. An infrared absorption band at ~1090 cm?1 was attributable to the thiirane group. The biological activity of these three sulfur-containing JH mimics was tested on Culex pipiens, Aedes aegypti and Spodoptera litura to reveal weak or no JH-like activity. 相似文献
468.
Guido Bonthond Till Bayer Stacy A. Krueger-Hadfield Nadja Strck Gaoge Wang Masahiro Nakaoka Sven Künzel Florian Weinberger 《The ISME journal》2021,15(6):1668
Invasive species are co-introduced with microbiota from their native range and also interact with microbiota found in the novel environment to which they are introduced. Host flexibility toward microbiota, or host promiscuity, is an important trait underlying terrestrial plant invasions. To test whether host promiscuity may be important in macroalgal invasions, we experimentally simulated an invasion in a common garden setting, using the widespread invasive macroalga Agarophyton vermiculophyllum as a model invasive seaweed holobiont. After disturbing the microbiota of individuals from native and non-native populations with antibiotics, we monitored the microbial succession trajectories in the presence of a new source of microbes. Microbial communities were strongly impacted by the treatment and changed compositionally and in terms of diversity but recovered functionally by the end of the experiment in most respects. Beta-diversity in disturbed holobionts strongly decreased, indicating that different populations configure more similar –or more common– microbial communities when exposed to the same conditions. This decline in beta-diversity occurred not only more rapidly, but was also more pronounced in non-native populations, while individuals from native populations retained communities more similar to those observed in the field. This study demonstrates that microbial communities of non-native A. vermiculophyllum are more flexibly adjusted to the environment and suggests that an intraspecific increase in host promiscuity has promoted the invasion process of A. vermiculophyllum. This phenomenon may be important among invasive macroalgal holobionts in general.Subject terms: Symbiosis, Molecular ecology, Microbial ecology 相似文献
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470.
Masahiro Nakaoka Norihiko Ito Tomoko Yamamoto Takehiro Okuda Takashi Noda 《Ecological Research》2006,21(3):425-435
Factors and processes affecting community structures operate at various spatial and temporal scales. We analyzed how similarities
of rocky intertidal assemblages vary at different spatial scales using a nested, hierarchical sampling design. Intertidal
assemblages consisting of algae, sessile animals, and mobile animals were censused on five rock walls at each of five shores
chosen within each of six regions along the Pacific coast of Japan, encompassing 1,800 km of coastlines. Based on this sampling
design, similarities in assemblages were calculated using both qualitative (presence/absence) and quantitative (percent cover
and density) data, and compared at three spatial levels: (1) rock level (the finest spatial scale, encompassing several to
hundreds of meters), (2) shore level (the intermediate spatial scale, encompassing several to tens of kilometers), and (3)
region level (the broadest spatial scale, encompassing hundreds to thousands of kilometers). Cluster analysis showed that
assemblages were categorized into distinct regional groups except for the two southern regions, but they did not separate
clearly from each shore. A nested analysis of similarities revealed significant variation in similarities among regions and
among shores within each region, with the former showing greater variation. Similarity was negatively correlated with geographic
distance at the regional level but not at the shore or the rock levels. At the regional level, similarity decreased more rapidly
with distance for mobile animals than sessile organisms. The analyses highlighted the importance of broad-scale abiotic/biotic
factors such as oceanic current conditions and biogeographic factors in determining observed patterns in similarity of rocky
intertidal assemblages. 相似文献