Rearranged karyotypes of 2n=5 present in three plants of Haplopappus gracilis (2n=4) were cytogenetically analyzed to clarify the origin of an additional centromere in the chromosome complement. One of the plants was a progeny of the homozygote with normal chromosome 1 crossed with the heterozygote with normal and centromere-shifted chromosome 1. The other two plants were derived from seedlings irradiated with X-rays during early germination stage. The chromosome complement of 2n=5 found in the first plant was comprised of 3 normal chromosomes (one chromosome 1 and two chromosome 2) and two rearranged chromosomes each possessing a centromere at the subterminal position. All the chromosome complements of the irradiated plants were similar to each other and each consisted of three normal chromosomes (one chromosome 1 and two chromosome 2) and 2 rearranged chromosomes, one large and metacentric and the other, fragment-like. The origin of the additional centromere in each complement of 2n=5 is discussed from the point of chromosomal evolution in the genus Haplopappus.

抄録全体を表示

Fluorescence in situ hybridization (FISH) using an Arabidopsis-type telomeric sequence (TTTAGGG)_n probe to the mitotic chromosomes of Haplopappus gracilis (n=2) revealed the presence of Interstitial Telomere-like Repeats (ITRs) in at the subdistal position of the long arm of both chromosome pairs (1g and 2g). The H. gracilis genome (n=2) is generally thought to reconstitute from the n=4 complement of the allied species, H. ravenii. The sites we identified by FISH are in close proximity to the chromosomal rearrangement fusion points. This evidence supports the hypothesis that the karyotype of H. garacilis evolved from that of H. ravenii due to chromosome breakage and the subsequent end-to-end chromosome fusion.

抄録全体を表示

Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated ²⁵²Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, <b_n>, was 19 times higher than rate induced by ⁶⁰Co γ-rays. When neutron doses, D_n, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron- γ mixed radiation from a 1 W nuclear reactor, using the reciprocal of <b_n> as conversion factor, resulting D_n values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to γ-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.

抄録全体を表示

Following exposure to X-rays or reactor radiation at the early germinating stage, seedlings of Haplopappus gracilis (Nutt.) Gray were inspected for karyotypic changes in the meristems of lateral roots 2 months later. Among 210 plants studied in total, 12 were carriers of aberrant karyotypes in the root systems. One of them was a whole-body variant of spontaneous origin, showing a complete change of karyotype not only in the root system but also in the shoot system. The remainders were mosaics, showing a complete karyotypic change in one or more lateral roots but not in the whole root system. Of the 11 cases of aberrant karyotypes detected as inter-root mosaics, 5 were unique to the respective plants, each characterized by a specific kind of non-reciprocal translocation, reciprocal translocation or complex exchange; 2 were commonly characterized by a complex exchange; 3 were by a non-reciprocal translocation; one was characterized by a fragment chromosome accompanied with a shortened chromosome and was not distinguishable from the aberrant karyotype of spontaneous origin. These results support the conclusion that the chromosomes of H. gracilis possess the plasticity to rearrangements after irradiation. The repetitious occurrence of specific rearrangements in different plants and the recovery of fragment-bearing karyotype are discussed as suggestive evidence for the existence of preferential sites for breakage and rearrangement in H. gracilis genome.

抄録全体を表示

The effects of low-intensity pulsed ultrasound (LIPUS) on osteoclastogenesis were examined using fish scales that had both osteoclasts and osteoblasts. The binding of the receptor activator of NF-κB ligand (RANKL) in osteoblasts to the receptor activator of NF-κB (RANK) in osteoclasts induced osteoclastogenesis. Therefore, we focused on RANK/RANKL signaling. After 6 h of incubation following LIPUS treatment, mRNA expression of RANKL increased significantly. Resulting from the increased RANKL mRNA level, the expression of transcription-regulating factors significantly increased after 6 h of incubation, and then the mRNA expression of functional genes was significantly up-regulated after 12 h of incubation. However, the mRNA expression of osteoprotegerin (OPG), which is known as an osteoclastogenesis inhibitory factor, also significantly increased after 6 h of incubation and tended to further increase after 12 h of incubation. At 24 h of incubation, osteoclastic functional genes’ mRNA expression decreased to the level of the control. Furthermore, we performed an in vivo experiment with goldfish. Two weeks after daily LIPUS exposure, osteoclastic marker enzymes tended to decrease while osteoblastic marker enzymes were activated. The regeneration rate of the LIPUS-treated scales was significantly higher than that of the control scales. Thus, LIPUS moderately activates osteoclasts and induces bone formation.

抄録全体を表示

南関東から南東北の5ヵ所の社寺林で，それぞれ1～2年間かけて細胞性粘菌の調査を行い，Dictyostelium clavatum の出現頻度とマクロシスト形成の季節性を見いだした．本種は冬から春にかけて増殖し，同時にマクロシストを形成して秋まで休眠するものと考えられた．

抄録全体を表示

A proportional reducing valve has heen applied to an automatic transmission to control shift operation. The control system must be designed as cL robust control system considering modeling error caused by changes in characteristics of the valve and a frictional coefficient. In this study, a brake mechanisml of an automatic transmission is considered as a controlled plant. Two-degree of freedom control of rotating speed is studied in which the modeling error is took into account. A. feedback controller is designed based on μ synthesis. Adding a feedforward controller, a two-degree of freedom control system is constructed. The control system is examined experimentally using cl commercial proportional reducing valve. It is demonstrated that shift operation can be precisely controlled by the control system under the fluctuating factors.

抄録全体を表示

Osteocytes, osteoblasts (bone-forming cells), and osteoclasts (bone-resorbing cells) are the primary types of cells that regulate bone metabolism in mammals. Sclerostin produced in bone cells activates osteoclasts, inhibiting bone formation; excess production of sclerostin, therefore, leads to the loss of bone mass. Fish scales have been reported to have morphological and functional similarities to mammalian bones, making them a useful experimental system for analyzing vertebrate bone metabolism in vitro. However, whether fish scales contain cells producing sclerostin and/or osteocytes has not been determined. The current study demonstrated, for the first time, that sclerostin-containing cells exist in goldfish scales. Analysis of the distribution and shape of sclerostin-expressing cells provided evidence that osteoblasts produce sclerostin in goldfish scales. Furthermore, our results found that osteocyte-like cells exist in goldfish scales, which also produce sclerostin. Finally, we demonstrated that microgravity in outer space increased the level of sclerostin in the scales of goldfish, a finding suggesting that the induction of sclerostin is the mechanism underlying the activation of osteoclasts under microgravity.

抄録全体を表示

We have previously reported that microgravity promotes the activation of osteoclasts in cultured regenerating scales. This osteoclastic activation was induced by increased levels of receptor activator of the nuclear factor-κB ligand (RANKL). Therefore, we determined that RANKL is an important factor in evaluating osteoclastogenesis in bone tissue. However, the role of RANKL in fish scales is poorly understood. In the present study, we prepared antiserum against goldfish RANKL in rabbits and detected RANKL-producing cells in regenerating goldfish scales. Furthermore, we studied osteoclastic activation by the addition of RANKL to examine exogenous RANKL on osteoclastogenesis in regenerating goldfish scales. As a result, RANKL immune-positive cells were detected in grooves of regenerating scales. In addition, treating the regenerating scales with mammalian RANKL for 3 h significantly increased the expression of the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), which is essential for osteoclast differentiation. After 6 h of incubation with RANKL, the expression of cathepsin K, a functional osteoclastic gene, significantly increased. Furthermore, the molecules for osteoclast multinucleation and differentiation significantly increased following treatment with mammalian RANKL. Therefore, in fish scales as well as mammalian bone, we concluded that RANKL plays an important role in osteoclastogenesis.

抄録全体を表示

Paired Fricke solutions, made up from light water or heavy water and 0.8N in H₂SO₄ and 1mM in Fe(NH₄)₂(SO₄)₂ and NaCl, were calibrated with ⁶⁰Co γ rays and with mixed neutron and γ radiation from a ²⁵²Cf source. Absorbance increases, A_L and A_H, in light- and heavy-water Fricke dosimeters, respectively, increased with fast-neutron and γ-ray tissue doses, D_n (Gy) and D_γ (Gy), of the mixed radiation as follows: A_L=0.00178D_n+0.00371D_γ; A_H=0.00121D_n+0.00442DD_γ. G-values of 7.2 and 5.5 were obtained for ²⁵²Cf neutrons in light- and heavy-water Fricke dosimeters, respectively. When we applied the pair of equations to A_L and A_H values observed after exposure to mixed radiation in a nuclear reactor, resulting D_n and D_γ values agreed within 10% to doses measured with paired ionization chambers. Doses required for Fricke dosimeters were 5 Gy or more. In contrast, we found that micronuclear yields in onion roots can measure the neutron component of mixed radiation fields at the order of 10 cGy with reasonable accuracy even if the neutron to γ-ray dose ratio is unknown.

抄録全体を表示

The relative biological effectiveness (RBE) of mixed neutron and gamma-ray radiation emitted at a ²⁵²Cf source at the Research Institute for Radiation Biology and Medicine, Hiroshima University, compared with ⁶⁰Co gamma-ray radiation was determined. The tissue-absorbed dose contribution of the accompanying gamma radiation was about 35.7% to the total tissue-absorbed dose from the ²⁵²Cf mixed radiation. The ²⁵²Cf mixed radiation and ⁶⁰Co gamma rays produced approximate linear changes in the frequency of micronuclei induced in root-tip cells of Allium cepa L. onion seedlings after irradiation as dry dormant seeds with varying absorbed doses in onion seeds. Therefore, the RBE for radiation-induced micronuclei was calculated as the ratio of the slopes for the ²⁵²Cf mixed radiation and the ⁶⁰Co gamma rays. The deduced RBE value of ²⁵²Cf mixed radiation to ⁶⁰Co gamma rays to induce micronuclei in dry dormant onion seed cells was about 90.5 ± 3.6 (± 1σ); the RBE of neutrons from the ²⁵²Cf mixed radiation was about 150 ± 6 (± 1σ). Furthermore, the sensitivity ratio of the induction rate of micronuclei in dry dormant seeds to that in seedlings by neutrons from ²⁵²Cf mixed radiation was significantly different from that by ⁶⁰Co gamma rays. From these results, we concluded that the repair efficiency of DNA damage induced by neutrons may be different from that by gamma rays.

抄録全体を表示

Heki-ryu is one of the Japanese archery (Kyujutsu) schools. Heki-ryu was founded in the Muromachi Period and its leaders were as follows, the founder, Shigekata Yoshida, Shigemasa Yoshida, Yoshikata Sasaki, Shigetaka Yoshida, Shigetsuna Yoshida, Shigeuji Yoshida, Toyotaka Yoshida and the following persons with Toyotaka. The head family of Heki-ryu is the Yoshida family in Kawamori (modern Shiga Prefecture) Shigeuji founded a Heki-ryu faction called Insaiha in the Edo Period and created such new branch families as the Yoshida family in the domain of Ashimori (modern Okayama Prefecture). The Yoshida family of the Ashimori clan had old documents about the origin of Heki-ryu. There were two different stories in them. One was that Danjo Heki initiated Shigekata into the shooting method. This is the same as the introduction of Heki-ryu in Bugei-shoden. The other was that Danjo was another name of Shigekata, who was the lord of the castle in Kawamori with his brother, Shigeoki Yoshida. The documents containing this story were handed down confidentially. The Yoshida family in Kawamori had the family tree beginning with the ancestor of Shigekata, Kanehide Sasaki. The lineage included three generations: Yasuhide, , and Shigekata. The son of Kanehide, Yasuhide, was the lord of Yoshida Castle in Izumo-no-kuni (modern Shimane Prefecture). He lived in Yoshida-sho, a manor in Izumo-no-kuni, and the family became known as Sasaki-Yoshida. was the head of the Yoshida family before Shigekata moved it to Kawamori. Shigekata was the lord of Nodera castle in Kawamori. Kanehide was the son of Hideyoshi Sasaki who served Yoritomo Minamoto according to the study of Sasaki clan. The Sasaki family was assumed to be excellent archers because Hideyoshi and his sons were brave soldiers. The Sasaki Yoshida family may have created an original shooting method which developed into Heki-ryu. The relationship between the Sasaki-Yoshida family and Heki-ryu will be discussed in another article.

抄録全体を表示

The relative biological effectiveness (RBE) of various energy neutrons produced from a Schenkel-type accelerator at the Research Institute for Radiation Biology and Medicine, Hiroshima University (HIRRAC), compared with 60Co gamma-ray radiation was determined. The neutron radiations and gamma-ray radiation produced good linear changes in the frequency of micronuclei induced in the root-tip cells of Allium cepa onion irradiated as dry dormant seeds (seed assay) and seedlings (seedling assay) with varying radiation doses. Therefore the RBE for radiation-induced micronuclei can be calculated as the ratio of the slopes of the fitted linear dose response for the neutron radiations and the 60Co gamma-ray radiation. The RBE values by seed assay and seedling assay decreased to 174 7, from 216 9, and to 31.4 1.0, from 45.3 1.3 (one standard error), respectively, when neutron energies increased to 1.0 MeV, from 0.2 MeV, in the present study. Furthermore, the ratio of the micronucleus induction rates of seed assay to seedling assay by gamma-ray radiation was much lower than that by neutron radiations.

抄録全体を表示

島根県には日本で発達したたたら製鉄と関連のある特殊鋼関連企業の集積がある．島根大学ではキラリと光る地方大学実現と地域の金属産業の活性化に資するため交付金事業を活用し，次世代たたら協創センター（NEXTA）を設立した．オックスフォード大学教授をセンター長に迎え，材料工学の4つの柱をバランスよく配置し，先端金属素材のグローバル拠点の創出を目指している．

抄録全体を表示