研究者総覧

中島 敏幸 (ナカジマ トシユキ)

  • 大学院理工学研究科 環境機能科学専攻 教授
Last Updated :2020/11/10

研究者情報

学位

  • 理学博士(東北大学)
  • 学術修士(筑波大学)

J-Global ID

研究キーワード

  • 確率   生命システム   生命記号論   共生   生態系   進化   probability   living system   symbiosis   ecosystem   evolution   

研究分野

  • ライフサイエンス / 生物物理学
  • ライフサイエンス / 生態学、環境学

学歴

  • 1984年04月 - 1987年03月   東北大学大学院   生物科学研究科
  •         - 1987年   東北大学   Graduate School, Division of Bioresearch   Biological Bciences
  • 1981年04月 - 1983年03月   筑波大学大学院   環境科学研究科
  • 1977年04月 - 1981年03月   東京農工大学   農学部   植物防疫学科
  •         - 1981年   東京農工大学   Faculty of Agriculture

所属学協会

  • 日本進化学会   日本原生生物学会   科学基礎論学会   

研究活動情報

論文

  • 中島 敏幸
    Entropy 21 216 2019年02月 [査読有り][招待有り]
     研究論文(学術雑誌)
  • Toshiyuki Nakajima
    Progress in Biophysics and Molecular Biology 131 298 - 311 2017年12月 [査読有り]
     研究論文(学術雑誌) 
    Evolution by natural selection requires the following conditions: (1) a particular selective environment (2) variation of traits in the population (3) differential survival/reproduction among the types of organisms and (4) heritable traits. However, the traditional (standard) model does not clearly explain how and why these conditions are generated or determined. What generates a selective environment? What generates new types? How does a certain type replace, or coexist with, others? In this paper, based on the holistic philosophy of Western and Eastern traditions, I focus on the ecosystem as a higher-level system and generator of conditions that induce the evolution of component populations I also aim to identify the ecosystem processes that generate those conditions. In particular, I employ what I call the scientific principle of dependent-arising (SDA), which is tailored for scientific use and is based on Buddhism principle called “pratītya-samutpāda” in Sanskrit. The SDA principle asserts that there exists a higher-level system, or entity, which includes a focal process of a system as a part within it this determines or generates the conditions required for the focal process to work in a particular way. I conclude that the ecosystem generates (1) selective environments for component species through ecosystem dynamics (2) new genetic types through lateral gene transfer, hybridization, and symbiogenesis among the component species of the ecosystem (3) mechanistic processes of replacement of an old type with a new one. The results of this study indicate that the ecological extension of the theoretical model of adaptive evolution is required for better understanding of adaptive evolution.
  • Arno Germond, Toshiyuki Nakajima
    Biocommunication of Ciliates 253 - 275 2016年05月 論文集(書籍)内論文 
    Ciliates can develop facultative or permanent symbiotic associations with other species. The ecological success of mixotrophic symbiosis in ciliates lead us to question the physiological aspects and the evolutionary processes by which such associations can emerge, be maintained, and evolve. We highlight the symbiotic interactions between ciliated protozoan and other organisms, and discuss the general and essential aspects of these associations from the ecological and evolutionary perspectives. We first overview the ecological role of mixotrophic protists and the major types of symbiotic associations in aquatic environments (Sects. 15.2 and 15.3). Subsequently, we review the mechanisms employed for partner recognition and selective acquisition, for the infection process of symbiotic cells, and the physiological regulation used by the ciliate hosts to control or exploit these symbionts (Sect. 15.4). Lastly, we introduce a non-reductionist approach, by using an experimental synthetic ecosystem, which focuses on how ecosystem processes affect the emergence and evolution of symbiotic associations (Sect. 15.5).
  • Toshiyuki Nakajima
    PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY 119 3 634 - 648 2015年12月 [査読有り]
     
    Higher animals act in the world using their external reality models to cope with the uncertain environment. Organisms that have not developed such information-processing organs may also have external reality models built in the form of their biochemical, physiological, and behavioral structures, acquired by natural selection through successful models constructed internally. Organisms subject to illusions would fail to survive in the material universe. How can organisms, or living systems in general, determine the external reality from within? This paper starts with a phenomenological model, in which the self constitutes a reality model developed through the mental processing of phenomena. Then, the it-from-bit concept is formalized using a simple mathematical model. For this formalization, my previous work on an algorithmic process is employed to constitute symbols referring to the external reality, called the inverse causality, with additional improvements to the previous work. Finally, as an extension of this model, the cognizers system model is employed to describe the self as one of many material entities in a world, each of which acts as a subject by responding to the surrounding entities. This model is used to propose a conceptual framework of information theory that can deal with both the qualitative (semantic) and quantitative aspects of the information involved in biological processes. (C) 2015 Elsevier Ltd. All rights reserved.
  • Toshiyuki Nakajima, Yoshiyuki Fujikawa, Toshiyuki Matsubara, Mimi Karita, Akiko Sano
    BIOSYSTEMS 131 9 - 21 2015年05月 [査読有り]
     研究論文(学術雑誌) 
    The ecological mechanisms underlying the diversification of autotrophic species into endosymbiotic lifestyles and the ways in which the evolution of endosymbiotic species is ecologically and evolutionarily affected by sister lineages/lines that are adapted to extra-host environments remain unclear. In this paper, we investigated a differentiation process of algal species in which an endosymbiotic type was differentiated phenotypically from a free-living ancestral clone, by using an experimental model called the CET microcosm, which contains a green alga (Micractinium sp.), a bacterium (Escherichia coli), and a ciliate (Tetrahymena thermophila) cultured together without an external resource supply for over 5 years. We then analyzed the algal diversification process by comparing algal phenotypic properties regarding cell-aggregate formation and their effects on the survival of Tetrahymena (using a clone isolated on day 2668) in the absence of bacteria. We examined 13 Micractinium clones, including both ancestral and derived clones isolated from long-term (day 1819-1847) CET microcosm cultures. The results revealed that the free-living ancestral algal strain diversified in sympatry into an aggregap-forming type that associates with E. coli, and a non-aggregate-forming type that associates with Tetrahymena. Furthermore, a competition experiment revealed that the endosymbiotic (non-aggregate-forming) type was less adapted to the extracellular environment than the aggregate-forming type. This result suggests that severe competition with a nonendosymbiotic sister line in the extra-host environment favors the host-benefiting phenotype in an endosymbiotic line, because such symbionts can enhance the longevity of the host, thereby enabling the survival and reproduction of the symbiont within the host. (C) 2015 Elsevier Ireland Ltd. All rights reserved.
  • Arno Germond, Masahiro Inouhe, Toshiyuki Nakajima
    EUROPEAN JOURNAL OF PHYCOLOGY 49 4 526 - 537 2014年11月 [査読有り]
     研究論文(学術雑誌) 
    The mechanisms through which algae evolve physiological characteristics related to endosymbiotic associations with heterotrophic organisms remain unclear. We previously showed that a green alga (Micractinium sp.) was able to evolve a host (ciliate)benefiting phenotype that prolonged the longevity of Tetrahymena thermophila in the absence of bacteria during a 5-year culture period in an experimental microcosm. Comparative experiments between the ancestral alga (i.e. original) and evolved algal clones of the same lineage can be performed to analyse the mechanisms that underlie algal evolution during interactions with ciliates. Here, we investigated the effects of acidic conditions on algal physiology because the acidic conditions within the food vacuoles of Tetrahymena could potentially affect algal evolution during long-term interactions. It might be expected that algal clones isolated from T. thermophila hosts would have developed the ability to resist acidic conditions in order to establish within the host, when compared with the ancestral strain. Unexpectedly, comparative analyses demonstrated that acidic conditions with pH values ranging from 3.9 to 4.3 limited the growth of the isolated algal clones SC9-1 and SC10-2, whereas the ancestral strain could grow under these conditions. Acidic conditions were responsible for significantly lower chlorophyll a/chlorophyll b ratios in the isolated algal clones, and the isolated clone SC9-1 exhibited a high cellular content of chlorophyllide a during a short exposure to acidic conditions, suggesting that degradation of chlorophyll a occurred. Furthermore, acidic conditions increased the release of extracellular glycerol and sucrose in the SC9-1 clone. These results indicated that the ancestral strain showed phenotypic changes related to acidic conditions, which may reflect the ongoing development of an algal phenotype suited to symbiosis. Hypotheses are proposed to explain the limited growth of the isolated clones, and implications for the Micractinium-Tetrahymena association are discussed.
  • Arno Germond, Tadao Kunihiro, Masahiro Inouhe, Toshiyuki Nakajima
    BIOSYSTEMS 114 3 164 - 171 2013年12月 [査読有り]
     研究論文(学術雑誌) 
    Endosymbioses between phototrophic algae and heterotrophic organisms are an important symbiotic association in that this association connects photo- and heterotrophic metabolism, and therefore, affects energy/matter pathways and cycling in the ecosystem. However, little is known about the early processes of evolution of an endosymbiotic association between previously non-associated organisms. In previous studies, we analyzed an early process of the evolution of an endosymbiotic association between an alga and a ciliate by using a long-term culture of an experimental model ecosystem (CET microcosm) composed of a green alga (Micractinium sp.), a bacterium (Escherichia coli), and a ciliate (Tetrahymena thermophila). The results revealed that an algal type, isolated from 5-year cultures of the microcosm, prolonged the longevity of the ancestral and derived clones of T. thermophila in the absence of bacteria, suggesting that a cooperative algal phenotype that benefited the ciliate had evolved in the microcosm. Here, we investigated the physiological changes of the derived Micractinium clones that benefited Tetrahymena, focusing on the release of carbohydrates by and abundance of photopigments in the ancestral and 2 derived algal clones (SC10-2 and SC9-1) isolated from inside Tetrahymena cells. Analyses using HPLC revealed that the algal isolates released glycerol and sucrose at higher concentrations per cell and also contained higher levels of photopigments per cell at pH 7.2, in comparison with the ancestral strain. These phenotypic characters were considered responsible for the increased longevity of Tetrahymena cells, and thus supported the cooperator alga hypothesis. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
  • Toshiyuki Nakajima, Toshiyuki Matsubara, Yuko Ohta, Daisuke Miyake
    BIOSYSTEMS 113 3 127 - 139 2013年09月 [査読有り]
     研究論文(学術雑誌) 
    Controversy persists as to whether the acquisition of beneficial metabolic functions via endosymbiosis can occur suddenly on an evolutionary time scale. In this study, an early stage of endosymbiotic associations, which evolved from previously unassociated auto (photo)- and heterotrophic unicellular organisms was analyzed using an experimental ecosystem model, called CET microcosm. This ecosystem model was composed of a green alga (Micractinium sp.; formerly described as Chlorella vulgaris), a bacterium (Escherichia coli), and a ciliate (Tetrahymena thermophila). Our previous study using a CET microcosm that was cultured 3-5 years revealed that fitness of the ciliate increased by harboring algal cells within its own cells. This fact suggested three possibilities: (i) the ciliate evolved the ability to exploit intracellular algal cells ("exploiter ciliate hypothesis"), (ii) the alga evolved the ability to benefit the host ciliate by providing photosynthates ("cooperator alga hypothesis"), and (iii) a combination of (i) and (ii). To test these hypotheses, two-by-two co-cultures were conducted between the ancestral or derived ciliate and the ancestral or derived alga. The experimental results demonstrated that a cooperative alga evolved in the microcosm, although the possibility remains that an exploitative genotype of the ciliate might also exist in the population as a polymorphism. Remarkably, an algal isolate prolonged the longevity of not only the isolated ciliate, but also the ancestral ciliate. This result suggests that once a cooperative algal genotype evolves in a local population, it can then be transmitted to other individuals of the prospective host species and spread rapidly beyond the local range due to its positive effect on the host fitness. Such transmission suggests the possibility of a sudden acquisition of beneficial autotrophic function by the pre-associated host. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
  • Toshiyuki Nakajima
    PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY 113 1 67 - 79 2013年09月 [査読有り]
     
    Probability is closely related to biological organization and adaptation to the environment. Living systems need to maintain their organizational order by producing specific internal events non-randomly, and must cope with the uncertain environments. These processes involve increases in the probability of favorable events for these systems by reducing the degree of uncertainty of events. Systems with this ability will survive and reproduce more than those that have less of this ability. Probabilistic phenomena have been deeply explored using the mathematical theory of probability since Kolmogorov's axiomatization provided mathematical consistency for the theory. However, the interpretation of the concept of probability remains both unresolved and controversial, which creates problems when the mathematical theory is applied to problems in real systems. In this article, recent advances in the study of the foundations of probability from a biological viewpoint are reviewed, and a new perspective is discussed toward a comprehensive theory of probability for understanding the organization and adaptation of living systems. (C) 2013 Elsevier Ltd. All rights reserved.
  • Arno Germond, Hiroki Hata, Yoshiyuki Fujikawa, Toshiyuki Nakajima
    European Journal of Phycology 48 4 485 - 496 2013年 [査読有り]
     研究論文(学術雑誌) 
    Recent phylogenetic studies of Chlorella-like algae revealed that this group has diversified into free-living and endosymbiotic niches, the latter within protists and invertebrate organisms. Our previous studies using a long-term culture composed of an alga (Chlorella vulgaris, rDNA sequence unknown), a bacterium (Escherichia coli) and a ciliate (Tetrahymena thermophila), suggested that some clones in the algal population developed an endosymbiotic ability with T. thermophila while others developed an ectosymbiotic ability with E. coli from a non-associated stage. In this paper, an rDNA (18S, ITS1, 5.8S, ITS2)-based phylogeny of the ancestral strain and derived clones isolated from 5-year microcosm cultures was constructed and revealed that the alga belongs to the genus Micractinium. This result was supported by analysis of the secondary structure of the rRNA gene. No difference was observed in the sequence between the ancestral and derived clones. On the other hand, some morphological and physiological traits of the ancestral strain and the derived clones were analysed and revealed that several phenotypic changes had occurred among the algal clones. In particular, the derived clones obtained from long-term cultures had increased in cell size, changed in their ability to grow at pH 4.0, and developed a tendency for cell-aggregation or sedimentation. © 2013 © British Phycological Society.
  • Toshiyuki Nakajima
    BIOSYSTEMS 108 1-3 34 - 44 2012年04月 [査読有り]
     研究論文(学術雑誌) 
    Epistatic interactions between genes in the genome constrain the accessible evolutionary paths of lineages. Two factors involving epistasis that can affect the evolutionary path and fate of lineages were investigated. The first factor concerns the impact of competition with another species lineage that has different epistatic constraints. Five enteric bacterial populations were evolved by point mutation in medium containing a single limiting resource. Single-species and two-species cultures were used to determine whether different asexual lineages have different capacities for producing variants due to epistatic constraints, and whether their survival is determined by local inter-lineage competition with different species. Local inter-lineage competition quickly resulted in one successful lineage, with another lineage becoming extinct before finding a higher peak. The second factor concerns a peak-shifting process, and whether the sexual recombination between different demes can cause peak shifts was investigated. An Escherichia coli population consisting of a male (Hfr) and female strain (F-) was evolved in a single limiting resource and compared to evolving populations containing the male or female strain alone. The E. coli sexual lineage was successful due to its ability to escape lower peaks and reach a higher peak, not because of a rapid approach to the nearest local peak the male or female asexual lineage could reach. The data in this study demonstrate that lineage survivability can be determined by the ability to produce beneficial mutations and checked by local competition between lineages of different species. Interspecific competition may prevent a population from evolving through crossing fitness valleys or adaptive ridges if it requires many generations to achieve peak shifts. The data also show that genomic recombination between different conspecific lineages can rapidly carry the combined lineage to a higher peak. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
  • Toshiyuki Nakajima, Akiko Sano, Hideaki Matsuoka
    BIOSYSTEMS 96 2 127 - 135 2009年05月 研究論文(学術雑誌) 
    We investigate an ecological mechanism by which endosymbiotic associations evolve, with a particular focus on the relationship between the evolution of endosymbiosis between auto-and heterotrophic organisms, and the stages of ecosystem development. For this purpose we conducted a long-term microcosm culture composed of three species, a green alga (Chlorella vulgaris), a bacterium (Escherichia coli), and a ciliated protozoan (Tetrahymena thermophila) for 3 years. During this culture T thermophila cells harboring Chlorella cells emerged by phagocytotic uptake, and increased in frequency, reaching ca. 80-90%. This level was maintained in the late stage of ecosystem dynamics. Analysis of the ecosystem dynamics in the microcosm revealed that a complex causal process through direct/indirect interactions among ecosystem components led to reduction in dissolved 02 and food (E. coli) available to the T thermophila, which gave a selective advantage to the organisms in the endosymbiotic association. This result suggests that the endosymbiosis evolves in a mature stage of ecosystem development, where reproduction and survival of prospective partner organisms is highly resource-limited and density-dependent, favoring efficient matter/energy transfers among participating organisms due to physical proximity. Consequently, a complex web of interactions and pathways of matter/energy flow in ecosystem evolves from an initially simple one. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
  • Akiko Sano, Motoyasu Watanabe, Toshiyuki Nakajima
    SYMBIOSIS 47 3 151 - 160 2009年 研究論文(学術雑誌) 
    We investigated directly air early stage of the development of ail endosymbiosis between air alga and a ciliate, beginning from a non-associated stage by conducting a long-term microcosm Culture composed of a green alga (Chlorella vulgaris). a bacterium (Escherichia coli) and a ciliate (tetrahymena thermophila) for three years. During this culture, Chlorella-harboring Tetrahymena appeared and increased in frequency. We examined the adaptive characteristics of the T. thermophila in association with the C. vulgaris derived from a well-established microcosm culture maintained for 1164-1400 days. and compared it with the original Culture of T. thermophila. The T. thermophila with the associated, intracellular C. vulgaris grew at a lower density of E. coli than the original T. thermophila with the original C. vulgaris, and the former survived longer than the latter in the absence of E.. coli. These results Suggest that this induced algal-ciliate association confers some fitness advantage at least to the host under the conditions of less or no available food Such as E. coli. Although the algal-ciliate association is riot completely stable, this quasi-stable association may enable the host to exploit a new niche through the advantages of mixotrophy.
  • 生命の階層システムにおける上向および下向決定性:適応進化を捉え直す
    科学基礎論学会科学基礎論研究 36 2 23 - 32 2009年
  • 中島 敏幸
    科学基礎論研究 36 2 67 - 76 科学基礎論学会 2009年 
    A hierarchical view of natural systems provides an effective framework to describe a given process of interest effectively by focusing a particular hierarchical level. However, this raises a serious problem, how is the focal level restricted or determined by the upper and lower levels? This problem is seen in the theory of natural selection. The theory explains the evolution of a population of biological entities as an automatic consequence of differential heritable fitness among variants, in which the complex biotic/abiotic interactions are put into a black box ("environment"), and the existence of the variants is presupposed; no interactions are explicitly incorporated into this explanation between the focal (population) and the upper/lower levels. In this paper I analyze the inter-level interactions involved in the process of adaptive evolution, and show that it proceeds under upward determination (i.e. generation of novel genetic variants) from the lower level, and under downward one from the upper level such as ecosystem (i.e. supply of new genetic information, creation of selective environments, and dynamic mechanism of replacement).
  • 生命システムは事象の確率をどのようにコントロールするか?-内的確率概念と生命の秩序生成
    科学基礎論学会科学基礎論研究 32 7-19.  2005年
  • T Nakajima
    INTERNATIONAL JOURNAL OF GENERAL SYSTEMS 33 5 505 - 526 2004年10月 [査読有り]
     研究論文(学術雑誌) 
    Living systems (entities) possess the property of maintaining their organization by continual renewal or production of components by themselves. Based on this self-maintenance ability, they reproduce systems of similar organization. This two-fold property forms unique hierarchical organizations, foreign to physical systems. This paper explores how the living world is organized by the two-fold property, where two types of hierarchical organizations, or part-whole relationships, are distinguished: one is synchronic participation in organizing an entity; the other is diachronic. The former implies that the composition of an entity is fixed through time, regardless of organizational patterns, while the latter involves changes in composition to maintain a pattern. Both types of organization are mathematically formalized, and organizational hierarchies of the living world are analyzed in biological space-time. This analysis reveals that biological systems are arrayed in a complex two-dimensional hierarchical matrix of synchronic and diachronic organization.
  • T Nakajima
    JOURNAL OF THEORETICAL BIOLOGY 221 1 39 - 51 2003年03月 [査読有り]
     研究論文(学術雑誌) 
    The same event may not necessarily occur against a given cognition (action) upon repetition. The degree of certainty in which a particular event actually occurs following a current cognition is the probability of the event viewed (experienced) by the focal cognizer. This is the internal concept of probability, which is contrasted with the external probability concept, the probability viewed by the meta-observer located outside the system, expressed as the relative frequencies of events. The internal probability may be,a measure of the adaptive cognitions or actions of a cognizer by which it generates or maintains a particular relation to its surroundings. In this paper, the quantitative description of encounter probabilities based on the internal concept is explored in the framework of the cognizers system model. The internal analysis derives the same formulation as that derived by the meta-observer concept of probability reported in a previous paper (Nakajima, 2001a), indicating the theoretical consistency of encounter probabilities between the analyses by the two contrasting probability concepts. The formulation suggests that a cognizer can raise (or reduce) the encounter probability with targets by a discriminative and selective response to a given situation, which describes a quantitative aspect of biological adaptation to the environment. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • Activity of Chlorella vulgaris associated by Exgerichia coli wello on removeal of total organic carbon in continuous river water flow system
    Algae 17(3) 195 - 199 2002年
  • T Nakajima
    JOURNAL OF THEORETICAL BIOLOGY 211 4 347 - 363 2001年08月 研究論文(学術雑誌) 
    Encounters between objects play a crucial role in creating specific patterns of organization in many biological systems. This paper explores a general, quantitative principle of encounter probabilities, applicable over various levels of organization, as a fundamental step toward a comprehensive theory of biological probability ranging from cells through organisms to ecological communities. Based on the cognizers-system model, a general description of encounter probabilities in a finite position space is derived as a function of the number, or density, of objects with cognitive, selectivity properties incorporated as parameters. There is a prevailing wisdom, as supposed in marry scientific thoughts, that the per-unit-time number of encounters between focal and target objects is given as a linear function of the density of target objects. One result shows that this idea does not describe the real nature of encounter probabilities or rates, but only a special case or approximation of a fundamental description. The analysis also explicates conditions for ignoring the presence of non-target objects, and those for the aggregation of two or more different objects into the same type sharing the same cognitive properties in the description of the probabilities. (C) 2001 Academic Press.
  • T Nakajima
    INTERNATIONAL JOURNAL OF GENERAL SYSTEMS 30 6 681 - 702 2001年 研究論文(学術雑誌) 
    This paper addresses the problem of how the self can know the existence of external reality, an environmental whole called proto-reality, in relation to metaphysical properties, deterministic or not, of worlds that the self can know. The self can only construct an outside within itself. Hence, departing from a solipsistic world where no external reality is assumed, the principle-based generation of external reality is articulated from a given perceptual sequence consisting of indubitable, direct percepts. New, external symbols are derived by an algorithmic rule called inverse causality operating on a given perceptual sequence. Three forms of world arise depending on the applied level of operation of the algorithm: part (the self) or whole (the self plus perceived reality). These include a solipsistic world; a semi-deterministic (positivistic) world composed of the self and what the self can directly discriminate; and a deterministic world composed of the self and what the self can discriminate either directly or indirectly.
  • T Nakajima
    JOURNAL OF THEORETICAL BIOLOGY 200 1 77 - 95 1999年09月 研究論文(学術雑誌) 
    This paper analyses relationships between probabilities of events happening in biological systems (or probabilistic disposition of systems) and cognitive properties of biological entities comprising such systems. Two kinds of cognitive properties are identified as relevant to the current problem: the ability to respond differently against different configurations of the environment (discriminability of cognition), and the ability to make an appropriate response to maintain a particular relation with the environment (selectivity of cognition). A basic framework bridging the two features of living systems, probabilistic disposition and the cognitive properties, is presented towards a general theory explaining the process generating probabilities of biological events, in this framework, a deterministic model of a system of entities is developed, in which objects are described as subjects that cognize events (i.e. entities as cognizers). Cognition is used in a wider sense, including not only biotic but also abiotic, and cognizers are conceptually distinguished from the mete-observer who describes the system externally. Based on this perspective, this paper seeks to explicate how events can occur in an uncertain, probabilistic manner, if observed from a cognizer viewpoint, even under a deterministic system. Each cognizer is identified with both the set of states that are actually taken, and its motion function which maps its state uniquely to a successor state depending on the current states of itself and of the rest of cognizers constituting the system. The model analysis reveals that the cognitive properties, discriminability and selectivity, of a cognizer can contribute to determining the probability of an event encountered by the cognizer itself-in particular, discrimination reducing the uncertainty in events occurrence for the cognizer. Biological implication of this result is discussed focusing on the concept of the probability of survival and reproduction. (C) 1999 Academic Press.
  • T Nakajima
    JOURNAL OF THEORETICAL BIOLOGY 190 4 313 - 331 1998年02月 
    The current theory of natural selection explains that adaptive evolution occurs because genotypes with greater survival or reproductive tendencies, due to their particular biological properties, tend to increase in frequency over the lesser ones in a common environment; therefore, the former will eventually replace the latter. In nature, such a selection process most often occurs in a local population which is nested in a community involving local ecological dynamics which are not clearly articulated in the explanatory scheme of the theory. This paper seeks to explicate such an ecological process giving rise to the evolution of a local population with a particular focus on dynamic effects of an increase in the number of invasive, new types on the fate of old ones. Arguments using the ecological-mechanistic model, representing negative interactions among alternative types of organisms, suggest major ecological mechanisms by which the new replace the old; a selective increase in the number of one type leads to a decrease in the equilibrial abundance of a limiting resource, an increase in the density of conspecifics, and/or an increase in the density of predators, which would in turn lower the per capita reproductive rate, or raise the mortality rate of another and make it extinct. Thus, replacement due to selection is associated with such dynamic shifts in equilibria occurring in a local community. The analysis of three (a resource, a prey and a predator) and four species (those plus a top predator) models suggests that evolutionary processes cannot be predicted without reference to the web structure of the community, that some fitness components causing a selective increase in a particular type can have, in some cases, nothing to do with factors causing selective decreases in alternatives, and that evolution of some traits can occur without resource competition. (C) 1998 Academic Press Limited.
  • TOSHIYUKI NAKAJIMA, SADAKO YAMADA
    Jpn. Journal of Water Treatment Biology 34 2 27 - 44 1998年
  • 中島 敏幸, 稲森 悠平, 遠藤 銀朗, 川端 善一郎, 栗原 康
    日本微生物生態学会 13 4 217 - 233 日本微生物生態学会 1998年 研究論文(学術雑誌)
  • 中島敏幸
    日本生態学会誌 45 1 43 - 56 1995年04月
  • 自然選択の因果機構
    科学基礎論研究 22 2 15 - 21 1995年
  • T NAKAJIMA, Y KURIHARA
    OIKOS 71 1 24 - 34 1994年10月 研究論文(学術雑誌) 
    Microevolutionary dynamics involving changes in both population densities and composition were studied by conducting long-term experimental cultures of the bacterium Escherichia coli and the protozoan Tetrahymena thermophila. We focussed on the mechanisms by which an increase of a mutant with a higher growth rate and/or lower mortality leads to decreases in original phenotypes, with a particular emphasis on ''predator-mediated (apparent) competition''. The bacterial population was cultured together with the protozoan population over a long period of time. These were contrasted with single-species control cultures of E. coli (i.e., without predator) experiencing high density-independent mortality from continual dilution of the population, and also a population with strong density-dependent regulation arising from intraspecific competition. The long-term cultures of predator and prey revealed the following changes: predator density increased for some time after inoculation; correspondingly, the specific growth rate of prey increased, and mutants with the long-cell form (which experience low predation rate) appeared and increased in frequency in the population. Comparison of these results with results from control cultures, suggests that predator-mediated competition existed between mutants and the original types in the predator-prey system, i.e., increases in densities of mutants with higher growth rate and/or lower predation rate in the prey population enhanced the predator equilibrium density, which in turn exerted higher predation pressure on the original prey which then decreased in abundance.
  • T NAKAJIMA, Y KURIHARA
    OIKOS 71 1 35 - 39 1994年10月 研究論文(学術雑誌) 
    A causal mechanism of replacement of variants in a prey population through predator-mediated competition was investigated using a mathematical model, and experimental results obtained in an accompanying paper were explained. The model shows that an increase in intrinsic growth rate and/or a decrease in predation rate of prey can increase predator equilibrium density, at least under some conditions, which in turn causes negative growth rate of previous types of prey. It is also indicated that the predator's responses in density due to changes of the prey traits can be affected by trade-offs between two parameters of the prey, intrinsic growth rate and predation rate. These mathematical results can explain qualitative aspects of the experimental results.
  • T NAKAJIMA, Y KURIHARA
    OIKOS 69 2 217 - 223 1994年03月 研究論文(学術雑誌) 
    An experimental investigation of the evolution of dispersiveness was carried out using two strains of Eschericia coli: one growing homogeneously (i.e., dispersed growth) in liquid medium in a test-tube culture, the other growing with weak attachment to test-tube walls. Experiments were designed to explore the conditions under which the dispersive or adhesive (resident) traits of bacterial cells can evolve, with a particular focus on the trade-off of the advantage of avoiding intraspecific competition versus the ability to reduce density-independent mortality. Experimental results suggest that dispersiveness of a bacterial population can change through selection of a mutant with higher fitness caused by either avoiding intraspecific competitive pressure or by reducing mortality, in a manner dependent on prevailing ecological conditions.
  • 中島 敏幸
    科学基礎論研究 21 4 23 - 28 科学基礎論学会 1994年
  • TOSHIYUKI NAKAJIMA, KOICHI FUJII
    Bulletin of Japanese Society of Microbial Ecology 8 2 73 - 81 1993年
  • T NAKAJIMA, M TAKAHASHI
    WATER RESEARCH 25 10 1243 - 1247 1991年10月 研究論文(学術雑誌) 
    Using algal-positive phototaxis, the possibility of keeping a high density of algae and separating them from water (i.e. solids-liquid separation) for removal of nutritive substances was investigated. Euglena gracilis shows positive phototaxis. Culture medium containing the alga in a culture vessel (bioreactor) was transferred to a shaded vessel (i.e. photo-clarifier) part of which was exposed to a spotlight. The organisms gathering around the light were returned to the culture vessel, and the effluent was taken out from the shaded part and discharged out of the system. Two types of bioreactors having different types of photo-clarifiers were employed: vertical form (Type A) and horizontal form (Type B). Densities of E. gracilis in the culture vessel and effluent were examined in both types over the experimental period, and compared with a control system without a photo-clarifier. In both types the E. gracilis density in the effluent was lower than that in the culture vessel, whereas in the control system the density in the effluent was almost identical with that in the culture vessel. Separation efficiency was higher in Type B than in Type A. The obtained results indicate that it is possible to achieve solids-liquid separation by using algal phototaxis, and suggest a possibility of further improvement in the separation efficiency by modifying the structure of the photo-clarifier.
  • モノの運動における因果性と偶然性-生物と無生物の間にあるもの(単著)
    科学基礎論研究 20 1 39 - 45 1990年
  • モノの構造と運動について-生命現象の理解のために-(単著)
    科学基礎論研究 19 3 25 - 33 1989年

書籍

  • 生態系とダーウィン・マシーン ーマイクロコズムから見た適応進化ー
    中島 敏幸 (担当:共著, 範囲:10章)
    京都大学学術出版会 2019年03月 
    自然選択による進化の標準モデルは,生態系から部分である個体群を切り出し, それに関する幾つかの条件を考え,それらが成り立てば進化が起こるというモ デルである.しかし,このモデルでは適応進化の条件や機構である(1)選択環 境の生成,(2)新しい遺伝可能な変異の生成,および(3)変異体間の競争的排除 や多型保存の機構がブラックボックス化されている.本章では,これらの条件 の生成や機構における生態系の役割に焦点を当て,特に微生物を用いた実験進 化の検証データを参照しながら,適応進化と生態系の関係を紹介する.そこで は,生態系は個体群が適応進化するために必要な諸条件を生成する機構を持ち, 構成個体群の進化を駆動し規定することが示され,生態系自身も彼らの進化に よって変化する進化システムであることが結論される.
  • Symbiotic communication in ciliates
    中島 敏幸 (担当:分担執筆, 範囲:pp 257-275)
    Springer 2016年 18 18
  • Biosemiotics Research Trends
    Nova Science Publishers, Inc, 2007年
  • Biosemiotics Research Trends
    Nova Science Publishers, Inc, 2007年

講演・口頭発表等

MISC

産業財産権

共同研究・競争的資金等の研究課題

  • インビトロ合成生態系を用いた共生の起源と進化の解明
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2020年04月 -2023年03月 
    代表者 : 中島 敏幸
  • 藻類-原生動物の細胞内共生のインビトロ進化
    日本学術振興会:科学研究費助成事業(基盤C,特設分野)
    研究期間 : 2017年04月 -2020年03月
  • 人工生態系を用いた共生の進化の実験的解析
    日本学術振興会:科学研究費助成事業(基盤C)
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 中島敏幸
  • 人工生態系を用いた藻類と原生動物間の細胞内共生の初期過程の解析
    日本学術振興会:科学研究費助成事業(基盤C)
    研究期間 : 2013年04月 -2016年03月 
    代表者 : 中島敏幸
  • Theoretical Study on Biological Probability of Events
  • Study on Microbial Community Dynamics
  • Study on Evolutionary Dynamics of Ecosystems

委員歴

  • 2016年04月 - 現在   科学基礎論学会   奨励賞選考委員会
  • 2012年04月 - 2015年03月   科学基礎論学会   理事
  • 2004年 - 2005年   科学基礎論学会   学会賞選考委員   科学基礎論学会

愛媛大学教員活動実績

教育活動(B)

担当授業科目(B01)

  • 2019, 前期, 学部, 生物学ゼミナールⅠ
  • 2019, 前期, 学部, 生物学特別演習Ⅰ
  • 2019, 前期, 学部, 進化生物学
  • 2019, 前期, 学部, 卒業研究Ⅰ
  • 2019, 前期, 学部, 基礎生物学実験
  • 2019, 前期, 学部, 基礎生物学実験
  • 2019, 前期, 修士, 生態進化生物学
  • 2019, 前期, 修士, 生物環境科学高等実習Ⅱ
  • 2019, 前期, 修士, 生物学ゼミナールI
  • 2019, 前期, 修士, 生物学ゼミナールⅢ
  • 2019, 前期, 修士, 生物学課題実験I
  • 2019, 前期, 修士, 生物学課題実験Ⅲ
  • 2019, 前期, 学部, 基礎生物学実験
  • 2019, 前期, 学部, 進化生物学


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