論文 - 坂本 信介
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Optimization of inhaled anesthesia for Octodon degus using electroencephalography 査読あり
Ikai Y., Nagura-Kato G.A., Sakamoto S.H., Shinohara A., Koshimoto C.
Experimental Animals 74 ( 1 ) 93 - 103 2025年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Experimental Animals
Physiological responses to inhaled anesthetics vary among species. Therefore, a precise anesthetic technique is important for each individual species. In this study, we focused on the degu (Octodon degus), a small herbivorous rodent. Degus have recently begun to be used as laboratory models for brain research because of certain human-like characteristics, such as spontaneous development of Alzheimer’s disease. In this study, we evaluated appropriate induction and maintenance anesthesia conditions for isoflurane and sevoflurane in degus by a stimulation test, electroencephalography (EEG), minimum alveolar concentration (MAC), and vital signs. During induction, more rapid time to loss of the righting reflex and deeper anesthesia in degus were observed in isoflurane. The MAC value for degus were 1.75 ± 0.0% in isoflurane and 2.25 ± 0.27% in sevoflurane. Whereas some degus were awake during maintenance anesthesia using both anesthetics at concentrations of ≤2%, no rats were awake when using sevoflurane at a concentration of 2%. The duration of the total flat EEG, a measure of the depth of maintenance anesthesia, was longer for isoflurane than for sevoflurane. Furthermore, higher concentrations of both anesthetics suppressed the respiratory rate in degus. These new findings regarding inhalation anesthesia in degus will contribute to future developments in the fields of laboratory animals and veterinary medicine.
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Ishiniwa H., Okano T., Endoh D., Hirayama H., Yoshioka A., Yokohata Y., Shindo J., Koshimoto C., Shinohara A., Sakamoto S.H., Tamaoki M., Onuma M.
Scientific Reports 14 ( 1 ) 29706 2024年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Scientific Reports
The Fukushima Daiichi Nuclear Power Plant accident caused the release of large amounts of radioactive material into the environment. Radiation from radionuclides cause DNA lesions, mainly via oxidation, which adversely affect wild organisms by damaging their germ cells. Here, we investigated the effects of radiation on the reproductive organs of Japanese field mice (Apodemus speciosus) by estimating the dose rate of radiation exposure, the accumulation of DNA lesions, and the expression of DNA repair enzymes. In highly contaminated areas, mouse testes received a radiation dose rate > 0.1 mGy/d. According to the International Commission on Radiological Protection, there is a very low probability of effects in the reference rat species at this exposure level. The results of the current study do not definitively conclude that the expression of 8-oxoguanine DNA glycosylase 1 and superoxide dismutase in mouse testes increase with dose rate and lifetime dose. However, 8-hydroxy-2′-deoxyguanosine accumulation increases in a dose rate- and lifetime dose-dependent manner in mouse testes, but is not observed in the sperm of the cauda epididymis. These results suggest that, although DNA lesions occurred in male germ cells of Fukushima mice, most were successfully repaired by DNA repair enzymes at the observed gene expression level.
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Kodama T., Sakamoto S.H., Mori A.
Proceedings of the Royal Society B: Biological Sciences 291 ( 2027 ) 20240719 2024年7月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings of the Royal Society B: Biological Sciences
Understanding how environmental factors affect the performance of predators can provide profound insights into predator-prey interactions from evolutionary and ecological perspectives and the global distributional patterns of each taxon. Almost all venomous predators are ectotherms, with muscle contraction properties depending on temperature. For predators having venom transportation systems driven by muscle contraction, temperature may have quite large effects on envenomation performance for prey subjugation. Here, we used videography and enzyme-linked immunosorbent assay to examine thermal effects on envenomation kinematics and venom expenditure in predatory strikes of a venomous snake, the Mamushi Gloydius blomhoffii, to its main rodent prey at various body temperatures under both field and laboratory experimental conditions. Unexpectedly, we found that the thermal effects on envenomation performance are limited over nearly the entire ecologically relevant range of temperature (from 13.2°C to 26.2°C). Although temperature statistically significantly affected the mass of venom injected under field conditions, temperature explained only a minor proportion of the variation in venom expenditure. These findings suggest that the Mamushi is able to maintain prey subjugation performance across a wide range of temperatures, which is highly advantageous for ectothermic predators. Further studies should examine the underlying mechanisms of the limited thermal effects and their ubiquity across venomous predators.
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Tone M., Ukyo R., Sakamoto S.H., Hemmi K., Kobayashi I., Tsuzuki Y.
Cryo-Letters 44 ( 5 ) 307 - 313 2023年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Cryo-Letters
BACKGROUND: Cryopreservation of porcine oocytes is difficult compared with other species and immature oocytes particularly so compared to the meiotic stage. OBJECTIVE: To evaluate the efficacy of a pretreatment with 1 μM paclitaxel (PTX, 30 min exposure) before vitrification to promote the maturation of porcine immature oocytes. MATERIALS AND METHODS: Cumulus cell-enclosed oocytes (COs) aspirated from porcine ovaries were divided into three groups: i) non-pretreated with PTX and non-vitrified group (control group); ii) pretreated with PTX and vitrified group (PTX-V group); and iii) non-pretreated with PTX and vitrified group (nPTX-V group). RESULTS: The nuclear maturation rate up to the preovulatory stage was significantly lower (P<0.05) in the nPTX-V group than in the control group, but was similar in the PTX-V and control groups. No significant differences were observed in viability assessed by a normal CO morphology and the embryonic development of oocytes activated by the parthenogenetic stimulation between the PTX-V and control groups, but not the non-PTX-V group. CONCLUSION: PTX may promote the maturation of vitrified porcine immature oocytes.
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Long-term behavioral effects of social separation during early life in a social mammal, Octodon degus. 査読あり
Ukyo R, Shinohara A, Koshimoto C, Nagura-Kato GA, Ieiri S, Tsuzuki Y, Sakamoto SH
Scientific reports 13 ( 1 ) 9518 2023年6月
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Identifying-and-counting based monitoring scheme for pigs by integrating BLE tags and WBLCX antennas 査読あり
Geunho Lee, Koki Ogata, Kikuhito Kawasue, Shinsuke Sakamoto, Seiji Ieiri
Computers and Electronics in Agriculture 198 2022年7月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Effects of aging and delivery order on the breeding capacity of F344/N rats. 査読あり
Sakamoto SH, Nishijima K, Ohno T, Tanaka S
The Journal of Veterinary Medical Science 84 ( 7 ) 960 - 963 2022年5月
担当区分：筆頭著者 記述言語：英語 掲載種別：研究論文（学術雑誌）
DOI： 10.1292/jvms.22-0111
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An attempt to clarify the causes of osteophagia among sika deer on Mageshima Island. 査読あり
Shichijo H, Tatsuzawa S, Sakamoto SH, Morita T
日本暖地畜産学会報 65 ( 2 ) 2022年3月
担当区分：責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌）
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Sakamoto SH, Miyamoto Y, Ukyo R, Ieiri S
The Journal of veterinary medical science 84 ( 5 ) 653 - 659 2022年3月
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Veterinary Medical Science
To strengthen farm biosecurity, wildlife behaviors around livestock environments require significant attention. Livestock feed is considered one of essential factors that attract wildlife to the livestock environment. We experimentally studied wildlife response to cattle, swine, and chicken concentrated feeds in the forests surrounding poultry farms. In 14 feeding sites, four feed conditions were established: without feed (control); cattle feed; chicken feed; and swine feed. Wildlife behaviors at each feed point were monitored using infrared cameras. In 3,175 videos, 10 mammals were photographed on 10 or more occasions. Wildlife more frequently appeared at the points with feed than without feed. In addition, the number of videos that captured foraging or interest behaviors was largest for swine feed, followed by chicken feed, then cattle feed. There was a large difference among wildlife in their response to livestock feeds, although each species did not have a strong preference for a specific feed. Livestock feeds invite frequent visits by high and moderate response groups, especially omnivores and carnivores with omnivorous tendencies. Therefore, to protect against such wildlife intrusion, leftover feed and feed storage must be properly managed. This study also suggests that livestock feeds may not cause intrusions by rare response group species; hence, if their intrusions occur, they may be due to factors other than livestock feed. The study situation can partly reflect actual feed-stealing situations. The results will contribute to consider the properly management to protect livestock environments from wildlife intrusions.
DOI： 10.1292/jvms.21-0627
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Body temperature measurement reveals the reproductive profile of female Apodemus speciosus under laboratory and field conditions. 査読あり
Kuroyanagi A, Ukyo R, Kodama Y, Eto T, Okubo Y, Kobayashi I, Ieiri S, Morita T, Sakamoto SH
Mammal study 47 ( 3 ) 2022年3月
担当区分：最終著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌）
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Antibiotic-resistant Escherichia coli isolated from dairy cows and their surrounding environment on a livestock farm practicing prudent antimicrobial use. 査読あり
Suzuki Y, Hiroki H, Xie H, Nishiyama M, Sakamoto SH, Uemura R, Nukazawa K, Ogura Y, Watanabe T, Kobayashi I
International journal of hygiene and environmental health 240 113930 2022年3月
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トクノシマトゲネズミ（<i>Tokudaia tokunoshimensis</i>）の生息記録と2005年～2016年の分布
城ヶ原 貴通, 中家 雅隆, 池村 茂, 越本 知大, 坂本 信介, 橋本 琢磨, 三谷 匡, 黒岩 麻里, 山田 文雄
哺乳類科学 60 ( 1 ) 105 - 116 2020年2月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本哺乳類学会
トゲネズミ属（<i>Tokudaia</i>）は琉球列島にのみ分布する固有属であり，トクノシマトゲネズミ（<i>Tokudaia tokunoshimensis</i>）は徳之島にのみ分布する固有種で，絶滅が危惧されている．本種の分布・生息状況についてはまとまった記録が蓄積されておらず，保全策を検討する上で分布・生息状況を明らかにする必要がある．本研究ではトクノシマトゲネズミの保全に向けた第一段階として本種の分布状況を明らかにするため，2011年から2015年の捕獲調査，自動撮影カメラによる調査に加え，2005年から2016年の目撃記録・直接観察の情報の整理ならびにその他の分布情報を精査した．その結果，トクノシマトゲネズミの分布は島北部の天城岳ならびに島中東部に位置する井之川岳周辺を分布の中心地域とし，南部の犬田布岳周辺にわずかに生息していることが明らかとなった．また，比較的良好な森林があるにも関わらず生息が確認できない地域が存在することが明らかとなった．本調査結果は，絶滅のおそれのあるトクノシマトゲネズミの保全地域の設定およびイエネコ（<i>Felis catus</i>）による捕食対策など生息地保全を含むさまざまな保全策の策定に基礎情報を提供するものである．
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ヨーロッパモリネズミにおける尿を用いたストレスホルモンの測定 査読あり
前山健太、篠原明男、仮屋博敬、川辺敏晃、城ヶ原貴通、名倉悟郎、坂本信介、越本知大
九州実験動物雑誌 35 29 - 38 2019年10月
記述言語：日本語 掲載種別：研究論文（学術雑誌）
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牧場施設内外および季節間での野生哺乳類の出現頻度の差異 査読あり
坂本 信介，畔柳 聴，右京 里那，小林 郁雄，家入 誠二
日本暖地畜産学会報 62 ( 2 ) 99 - 105 2019年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：日本暖地畜産学会
牧場への野生動物の侵入をカメラトラップ法で調べる際に，カメラの設置位置や設置時期によって結果が大きく変わるかを調べるため，同一牧場内の様々な施設の内外に 1 年にわたり自動撮影カメラを 9 台設置し，飼養形態や利用方式が異なる施設ごとにまた季節ごとに野生哺乳類の出現状況を比較した．哺乳類の撮影頻度は施設間で大きく異なっており，相対的に乳牛舎内，肥育牛舎外，繁殖牛舎外では，食肉類の撮影頻度が高い傾向にあった．また，肥育牛舎，繁殖牛舎，倉庫では，動物の撮影頻度のうちわけが施設の内外で大きく異なっていた．イエネズミとノネズミのどちらもが施設外で撮影されたため，イエネズミの施設内外の移動と施設外での両者の直接的・間接的接触が懸念された．また各動物の出現頻度には季節性が見られた．以上の結果から，牧場内でカメラトラップ法を用いる際には，撮影地点や設置時期の選定が調査結果に影響を及ぼすと考えられる．
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Wireless IC tag based monitoring system for individual pigs in pig farm 査読あり
Geunho Lee, Myungsik Kim, Kazuki Koroki, Atsushi Ishimoto, Shinsuke H. Sakamoto, and Seiji Ieiri
IEEE 1st Global Conference on Life Sciences and Technologies 168 - 170 2019年3月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Monitoring system based on active RFID tags for acquiring ecological data of individual pigs 査読あり
Geunho Lee, Kazuki Koroki, Takashi Yoshiura, Atsushi Ishimoto, Shinsuke Sakamoto, and Seiji Ieiri
Proc. 24th International Symposium on Artificial Life and Robotics 901 - 904 2019年1月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Behavioural interference among eusocial naked mole rats during work 査読あり
Kutsukake N., Inada M., Sakamoto S., Okanoya K.
Journal of Ethology 37 ( 1 ) 101 - 109 2019年1月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Ethology
It has been reported that individuals of cooperative breeding species occasionally interfere with the work of other group members. However, the occurrence and function of this behaviour are controversial. In the naked mole rat (Heterocephalus glaber), a eusocial mammal, individuals frequently perform ‘tail-tugging’ behaviour, in which an actor holds the tail of another individual with the mouth and pulls that individual to a different place. In this study, we investigated the possible function of this behaviour in the experimental setting of soil excavation. Behavioural observations on three colonies showed that this behaviour was performed and received by individuals of all individual categories (i.e. queen, reproductive males, and workers), although a queen in one colony performed 72.5% of the observed behaviour. Our data support the hypothesis that this behaviour is used to monopolise work in a specific space because (1) tail-tugging was more likely to occur when the actor and recipient were working than when they were not, and (2) the actor performed tail-tugging in a cell in which that individual worked frequently. This study provides a rare example of behavioural interference in a cooperative society and suggests that there is disagreement and conflict regards the opportunity to work among colony members in this eusocial mammal.
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牧場における畜産動物と畜舎周辺に生息する野生小動物の薬剤耐性大腸菌の実態調査 査読あり
廣木颯, 畔柳聴, 坂本信介, 小林郁雄, 上村涼子, 糠澤桂, 鈴木祥広
土木学会論文集G（環境） 74 ( 7 ) III_231 - III_238 2018年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 土木学会
畜産動物は抗菌薬を投与される場合があり，薬剤耐性菌の発生源となり得る．また，ネズミなどの小動物が，畜産動物の残餌やふんなどを摂餌する様子も観察されている．したがって，畜産動物から小動物へと薬剤耐性菌が伝播され，自然環境へ拡散する可能性は否定できない．本研究では，住吉牧場で飼育される肉用牛と畜舎周辺の野生ネズミを対象に，11種類の抗菌薬に対する薬剤感受性試験を実施した．ウシとネズミで，1剤以上に耐性を示した大腸菌が検出された個体の割合は，それぞれ50.0%と41.2％であった．また，両方のふん便からアンピシリンとテトラサイクリンに耐性を示した大腸菌が検出された．薬剤耐性を保有する畜舎内のウシと畜舎周辺におけるネズミの分布状況から，ネズミが薬剤耐性大腸菌を媒介し，環境に拡散している可能性が示唆された．
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Takeshi Eto, Shinsuke H. Sakamoto, Yoshinobu Okubo, Yasuhiro Tsuzuki, Chihiro Koshimoto, and Tetsuo Morita.
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 188 ( 6 ) 1005 - 1014 2018年11月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Daily torpor is a strategy used by some overwintering small endotherms to aid in energy conservation. However, the pattern of torpor varies among individuals within species and populations, even under the same environmental conditions, with significant implications for survival rate and reproductive success. Body mass is one factor that may influence this variation, especially in some small mammals that accumulate fat stores prior to overwintering. However, to our knowledge there has been no previous study examining the detailed relationships between torpor expression and body mass change in small mammals that hoard food as an energy resource during winter. The large Japanese field mouse, Apodemus speciosus, whose winter survival strategy depends on food caches instead of fat stores, displays daily torpor under artificial winter conditions (short-day photoperiod and cold). The present study clarifies the characteristics and patterns of daily torpor and body mass change in this species in the laboratory. Although expression of daily torpor was facilitated progressively as in other species, the observed patterns of torpor expression and body mass change showed considerable individual variation. Moreover, there was no obvious correlation between body mass and daily torpor expression. Therefore, it is suggested that in A. speciosus body mass may not contribute to individual variation of daily torpor during winter. Daily torpor during winter may be adjusted by not only mechanisms common to other small mammals, but also species-specific factors relating to the external or internal reserves of energy in small mammals.
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Individual differences in torpor expression in adult mice are related to relative birth mass 査読あり
Goro A. Kato, Shinsuke H. Sakamoto, Takeshi Eto, Yoshinobu Okubo, Akio Shinohara, Tetsuo Morita, and Chihiro Koshimoto
Journal of Experimental Biology 221 ( 12 ) jeb171983 2018年7月