巻号一覧
10 巻 (1996)
- 4 号 p. 247-
- 2 号 p. 97-
- 1 号 p. 3-
10 巻, 4 号
選択された号の論文の6件中1～6を表示しています
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Ken Ohnishi, Akihisa Takahashi, Hiroaki Tanaka, Takeo Ohnishi1996 年 10 巻 4 号 p. 247-251
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーThe catfish Synodontis nigriventris shows a unique habit taking a stable upsidedown posture in free water regardless of an above, one-sided illumination. This upsidedown posture can be observed when the catfish is apart from objects because the catfish usually orients its ventral side towards the water bottom or objects due to a so-called ventral substrate response. Thus, it is not easy to study the mechanism of the upside-down posture. To resolve this problem, the frequency of the upside-down posture was measured by using various sizes of vessel in which the catfish was kept. Video analysis showed that the frequency of the upside-down posture depended on the space size around the catfish. The smaller the size became, the higher the frequency of the upside-down posture became. Furthermore, the frequency of the upside-down posture depended on the shape of the vessel bottom. Curved-bottom vessels induced the upside-down posture more frequently than flat bottom. These findings suggest that a small, curved-bottom vessel is ideal for researching the upside-down postural control mechanism.抄録全体を表示PDF形式でダウンロード (1152K) -
Ken Ohnishil, Akihisa Takahashi, Masato Koyama, Takeo Ohnishi1996 年 10 巻 4 号 p. 252-258
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーThe upside-down catfish Synodontis nigriventris has a unique habit of swimming and resting upside-down in free water. This behavior leads to the assumption that the catfish has a specific gravity information processing system. We examined the postural control behaviors in the catfish under clinorotation which is usually used for producing pseudo-microgravity. Synodontis nigriventris kept its body posture at a stable area of the rotated flask in which the catfish was kept, when it was clinorotated at the rate of 60 rpm. In contrast to Synodontis nigriventris, a related species, Corydoras paleatus, did not show such steady postural control. When the flask was rotated at a lower rate of 30 rpm or a higher rate of 100 rpm, Synodontis nigriventris as well as Corydoras paleatus showed a considerable disturbed control of body posture. In this condition, they were frequently rotated with the flask. These findings suggest that Synodontis nigriventris has a high ability to keep upside-down posture and the gravity sensation in this catfish is likely to contribute to its different postural control from that of many other fishes.抄録全体を表示PDF形式でダウンロード (901K) -
野田 春彦1996 年 10 巻 4 号 p. 259-261
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーPDF形式でダウンロード (616K) -
土山 明1996 年 10 巻 4 号 p. 262-270
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーPossible relic biogenic activity in martian meteorite ALH84001 was proposed by McKay et al. (Science, 273,924-930, 1996). This ancient meteorite of 4.5 billion years old contains abundant carbonates as secondary minerals precipitated from a fluid on the martian surface. They showed the following lines of evidence for the ancient life; (1 ) unique mineral compositions and biominerals, (2) polycyclic aromatic hydrocarbons (PAHs) in association with the carbonates, and (3) unique structures and morphologies typical of nannobacteria or microfossils. This review is divided into two parts; one is on the martian meteorites in general and ALH84001, which has many features unlike other martian meteorites, and the other is on mineralogical (biomineralogical) and geochemical features of the carbonates and microfossil-like structures. There is little doubt that ALH84001 is from Mars as well as eleven other SNC meteorites. However, the mineralogical and biomineralogical evidence for martian bacteria given by McKay et al. (1996) is controversial, and could be formed by non-biogenic processes. Thus, further study of ALH84001 and other martian meteorites is required. We also need to consider the future Mars mission especially sample return mission.抄録全体を表示PDF形式でダウンロード (1115K) -
河崎 行繁1996 年 10 巻 4 号 p. 271-282
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーIn this review, I would like to introduce how we can detect the possible life on Mars. Even though the quantitative estimation of the possibility of biogenesis on Mars is difficult, Dr. McKay and his colleagues work has thrown a tiny light for this possibility. Considering Mars environmental conditions, the possible life is microorganisms. The detection of microorganisms in natural environments is not easy even on Earth due to the premature detection technique. We have developed a method based on the fluorescence microscopic technique. This method proved to be successful for the detection of terrestrial microorganisms. Even some pre-biotic cells can be detected. We are developing a miniature detection apparatus which meet the required standard for installing on the Mars landers. We also propose the ground based experiments using Martian meteorites or pseudo-Martian rocks.抄録全体を表示PDF形式でダウンロード (1688K) -
小池 惇平1996 年 10 巻 4 号 p. 283-288
発行日: 1996年
公開日: 2006/02/01
ジャーナル フリーIn connection with quarantine for interplanetary mission, we have examined the survivalities of terrestrial microorganisms under simulated Mars condition [I-91. In this study, the Mars conditions were simulated by ultraviolet and proton irradiation under similar low temperature, high vacuum and gaseous conditions by using cryostat vehicle. After exposure to the simulated Mars conditions, the survivabilities of the organisms were examined. From the results,the spores of Bacillus subtilis, the spores of Aspergillus niger, some anaerobic bacteria and algae showed considerable high survivalities even after UV and proton irradiations corresponding to 200 years on Mars. This subject is not restricted to academic curiosity but concerns problems involving the contamination of Mars with terrestrial organisms carried by space-probes. If there is a possibility that the terrestrial organisms carried from Earth to Mars can live for a significant period on Mars, a contamination of the Mars should be prevented for the purpose of life-detection-experiments in future.抄録全体を表示PDF形式でダウンロード (900K)
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