Masahiko Idei's research while affiliated with Bunkyo University and other places
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Publications (35)
Pleurosira laevis is a salt tolerant diatom distributed around the world. The valve of P. laevis has distinct structures called ocelli, which are sharply‐defined areas with fine, densely‐packed pores. Two formae of this diatom, P. laevis f. laevis and P. laevis f. polymorpha, are distinguished from each other by their flat or dome‐shaped valve face...
Diploneis species have perhaps the most complex valve structure among pennate diatoms. The development of this structure was studied in D. smithii and begins with the formation of a primary band, which then develops secondary arms at both poles and the center, as in the classic Chiappino–Volcani model of raphid diatom ontogeny. Spine-like projectio...
Spermatogenesis and auxospore development were studied in the freshwater centric diatom Hydrosera triquetra. Spermatogenesis was unusual, lacking depauperating cell divisions within the spermatogonangium. Instead, a series of mitoses occurred within an undivided cell to produce a multinucleate plasmodium with peripheral nuclei, which then underwent...
The past few decades have brought about a significant expansion in our understanding of the diatom life cycle, particularly its sexual part. Presented here is a set of proposals for the terminology of processes and structures associated with sexual reproduction and for the resting stages of diatoms, some of which have at times been confused with ea...
Selected serial transverse sections from the flagellum to the basal body in Melosira moniliformis var. octogona. TEM. a–e Enlargements of Fig. 8b, c, e, k and n, respectively. Scale bar = 200 nm
We give a detailed account of sexual reproduction and auxospore development in the diatom genus Diploneis, principally from clonal cultures of the marine benthic Diploneis papula. Sexual reproduction of D. papula was apparently homothallic. After pairing side to side, cells entered meiosis, and each gametangium produced two gametes. Fertilization w...
Three new Diploneis species are described from freshwater lakes in Japan. A complex wall structure is demonstrated in D. aokiensis sp. nov. and D. yamanakaensis sp. nov., where the basic alternation of transapical ribs (virgae) and striae is overlain by a system of secondary branches and struts supporting the external perforate surface. Diploneis l...
The most complete account to date of the ultrastructure of flagellate cells in diatoms is given for the sperm of Thalassiosira lacustris and Melosira moniliformis var. octogona, based on serial sections. The sperm are uniflagellate, with no trace of a second basal body, and possess a 9 + 0 axoneme. The significance of the 9 + 0 configuration is dis...
Surirella cf. fastuosa is an apparently isopolar elliptic marine raphid diatom. We observed cells before and after sexual reproduction in monoclonal cultures using light and scanning electron microscopy (LM and SEM). After sexual reproduction cells were approximately twice as large as before, in valve length and width. The stria and infundibula den...
cGametogenesis and auxospore development have been studied in detail in surprisingly few centric diatoms. We studied the development of sperm, eggs and auxospores in Actinocyclus sp., a radially symmetrical freshwater diatom collected from Japan, using LM and electron microscopy of living cultures and thin sections. Actinocyclus represents a deep b...
Sexual reproductive processes and the fine structure of auxospores in Calonis linearis, a marine raphid diatom, are described in detail. The auxosporulation of the species is of type IC (Geitler's classification); each of two paired cells produces two isogametes. Two zygotes (young auxospores) are formed with thin copulation mucilage in between the...
Autonomously folded thread on male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. Note the thread is folded near to the root from 00:04.58 onwards.
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Approach of male gamete to three eggs and fertilization in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. A male gamete moves toward eggs. Note that the male gamete selects an eggs: the first two eggs are not fertilized even though the cell surfaces come in contact.
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Nuclear behaviour in Pseudostaurosira trainorii visualized with DAPI. LM. Scale = 5 µm. A–C. Male clones. D–F. Female clones. G, H. Zygote. Bright field (1) and fluorescence image (2). A. Large nucleus at the centre, plastids appressed to valve. B. One nucleus per gamete after meiosis I. C. Meiosis II results in two nuclei per gamete. D. A large nu...
Result of pheromone experiment in Pseudostaurosira trainorii. LM (A–C) and time lapse LM (D, E). Scales = 50 µm (A–C) or 10 µm (D, E). A, B. Male (A) and female (B) partitions in Expt. 2 are filled with released gametes. C. Male gametes mixed with a vegetative female clone in Expt. 6. Male gametes are not attracted by a chain of vegetative female c...
Fusing threads on male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. Gamete spins to retrieve threads (until 00:15.88), which are then fused from proximal end (00:16.51 onwards). Note the gamete does not spin when the threads are fusing.
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Male gamete extruding a thread. LM. Scale = 5 µm. A. Bright field optics. B. Tubulin immunolocalization. C. DNA staining with DAPI. D. Merged image of B and C. E, F. Three-dimensional reconstruction based on 27 optical stacks taken every 0.21 µm and rotated ca. 230° (E) and 320° (F). Note that a thread stems from a tubulin ring on the equator of th...
Interrupted approach of a male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. A male gamete (bottom) approaches an egg cell, which is then fertilized by another male (top). The bottom male gamete does not head toward the zygote anymore, but instead starts wandering around the zygote. Male gametes and egg cells are marked m and e...
Male gamete in Pseudostaurosira trainorii retrieving the thread. Real-time movie from which Fig. 2 is composed. Cell spins at on its axis, remaining in the same place. The vacuole seems to be elastic as the shape is changed by the thread tension.
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Schematic illustrations of pheromone experiments showing male and female cells (blue and red dots, respectively), culture medium (light blue) and agar gel (light yellow). A. Expt. 2. Compatible clones in separate holes in an agar plate. B. Expt. 6. Male clone incubated with a block of agar gel containing filtrate of female vegetative clone. C. Expt...
Tests for mucilage around gametes and zygote in Pseudostaurosira trainorii. LM with India Ink (A–F) and SEM (G–I). Scales = 5 µm (F, G) or 2 µm (H). A–C. No mucilage envelope is seen on egg (A), two male gametes attaching to egg (B) nor early stage of zygote (C). D–F. Globular mucilage envelopes are seen around expanding zygotes (auxospores). Note...
Valve morphology in Actinocyclus. A–D. Light micrographs. E–M. Scanning electron micrographs. A–D. Valves. Scale bars = 10 µm. E. External oblique girdle view of a whole frustule composed of concave and convex valves, wide valvocopula and pleura. Scale bar = 10 µm. F. External view of valve showing pseudonodulus (arrow) and external openings of lab...
Background:
Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the form...
Thread behaviour of male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. When two threads fuse, a condensate (arrowhead) is formed at the bottom of the threads. The condensate moves distally as the gamete extrudes the thread, and then it moves back again proximally as the gamete retrieves the thread. Note that the shape of the co...
Male gamete in Pseudostaurosira trainorii with a blob. Real-time movie from which Fig. 3 is composed. The gamete retrieves the thread and then extrudes a blob with cell elongation. The blob is retrieved by the spinning gamete. Finer projections show somewhat autonomous movement.
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Vegetative cell in Pseudostaurosira trainorii. LM (A, B) and SEM (C, D). Scales = 5 µm (A), 2 µm (B, C) or 0.5 µm (D). A. Living cells attaching to each other to form a ribbon colony. B. Acid-cleaned valve showing parallel striae. C. Striae consisting of single rows of areolae. Valve with marginal spines. D. Enlargement of areolae, which are occlud...
Finer projections of male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. Finer projections are seen on the gametic surface as well as on the thread. Arrow and arrowhead indicate thread and finer projections, respectively.
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Male gamete liberation in Pseudostaurosira trainorii. Time lapse LM. Scale = 5 µm. The two gametes are unequal in size. The larger gamete (right) swells out from the gametangium.
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Retrieval and extrusion of thread of male gamete in Pseudostaurosira trainorii. Time lapse LM. Scale = 10 µm. A long thread is retrieved as the gamete spins, and then extruded again unless the thread is fully wound.
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Background: Diatoms belong to the stramenopiles, one of the largest groups of eukaryotes, which are primarily characterized by a presence of an anterior flagellum with tubular mastigonemes and usually a second, smooth flagellum. Based on cell wall morphology, diatoms have historically been divided into centrics and pennates, of which only the forme...
SUMMARYA small diatom, Hygropetra gelasina sp. nov., obtained from wet moss is described. This diatom is similar to Hygropetra balfouriana (Grunow ex Cleve) Krammer & Lange-Bertalot, which was found in the same moss sample. Fine structural observations revealed that H. gelasina has a reduced raphe slit and depressions along the margin of the axial...
This study clarifies the fine structure of the vegetative and initial valves of Achnanthes yaquinensis and briefly compares them to other Achnanthes species. It also elucidates the structure of the perizonium, based on auxospore development in short-term cultures. The araphid valve has marginal ridges and terminal spines that allow connecting valve...
The diatom genus Eunotia is unusual among raphid diatoms in having a raphe system consisting of two short slits that are not integrated into the primary pattern center. This and other characteristics, particularly the presence of rimoportulae, are consistent with the hypothesis that Eunotia is a basal lineage within the raphid group. We studied aux...
Citations
... The valves of Fallacia species undergo an outward development, suggesting the conopeum is formed after the basal valve layer. This is in contrast to Diploneis, in which the inner layer with sterna is developed after the formation of the outer surface layer (Idei et al. 2018). In raphid diatoms, vimines are usually developed distally from the raphe sterna to the valve margin (Cox 2012). ...
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... Navicula serians (Brébisson) Kützing] Caloneis -amphisbaena (Bory) Cleve [syn. Navicula amphisbaena Bory] § -linearis (Cleve) Boyer -silicula (Ehrenberg) Cleve § -ventricosa F. MeisterMann, 1989a;Ishii et al., 2012 Campylodiscus-neofastuosus Ruck et Nakov [syn. Surirella fastuosa (Ehrenberg) Ehrenberg] § ...
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... Idei et al (2013b); 51. Idei et al. (2015); 52. Iyengar and Subrahmanyan (1944); 53. ...
... However, there are several naviculoid genera in which, as in Sellaphora, the first band (the valvocopula) is by far the widest of the bands, and the bands further from the valve (the abvalvar bands sensu von Stosch 1975) are narrow strips or reduced to ligulae. This occurs, for example, in species of Pinnularia, Trachyneis, Rhoikoneis and Diploneis (Round et al. 1990, Idei 2013. Because this type of girdle is prevalent in a number of genera, some not closely related, and presumably has some functional significance, it seems worthwhile to have a term to describe it. ...
... In contrast, the lateral openings of the bands in surirelloid diatoms are not brought about by a shortening of the bands, but by a wholesale shift (a rotation) in their orientation relative to the long axis of the valve. This is perhaps not surprising given the huge change in symmetry relationships and ontogeny that has occurred in surirelloids, as a result of the extension of the raphe system around the whole circumference of the valve (Mann 2000, Watanabe et al. 2012. ...
Reference: A new type of girdle band in Bacillariaceae
... This process of 159 space division and cell division continues over generations till it reaches a point where no further space is 160available. That is when the diatom resorts to sexual reproduction via auxospore formation(Idei et al. 2013) and 161 creates a cell that attains maximum size. The cell is now ready to be divided asexually again.8Ciliates ...
... The classification in centrics and pennates, generally corresponding to a planktonic and benthic lifestyle (with the notable exceptions of Pseudo-nitzschia and Fragilariopsis, raphid diatoms with a planktonic lifestyle), also mostly mirrors the split between oogamous and anisogamous sexual reproduction, and homothallic and heterothallic mating systems [11]. of the mate recognition system. We report experimental evidence for the presence of sex pheromones that reciprocally stimulate the sexualization of compatible strains. ...
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... Minchin (1922) ranked Rhizomastigina as a suborder to embrace the genera Mastigella, Mastigamoeba, and Mastigina with single centrioles, thus excluding biciliates like Cercobodo, establishing a well defined monophyletic assemblage of mastigamoebae, and considered them related to Mycotozoa and Sarcodina and grouped them in the suborder Holomastigina (Multicilia) in an order Pantostomina (based on Saville Kent). Precisely the same three genera were accepted as order Rhizomastigina or Rhizomastigida (both spellings use) by Hyman (1940). It was demoted to family Mastigamoebidae by Chatton (1953) within order Amoebaea but reverted to order Rhizomastigida in Honigberg et al. (1964), but muddled by implicitly adding unrelated flagellates, ignored altogether by Levine et al. (1980) but retained as an order by Lee et al. (1985) who illustrated only the genera included by Minchin and did not realise that mastigamoebae were related to Entamoeba and both related to Pelomyxa; Lee et al. (1985) mistakenly called Rhizomastigida 'arteficial', and Bovee (1985) still had only Pelomyxa in Pelobiontida (within class Lobosea, then polyphyletic through including Schizopyrenida also) but kept Entamoeba in order Amoebida. ...
... 1990). У одних видов в перизониуме присутствуют как кольца, так и продольные ленты, у других только кольца, у небольшого количества видов обнаружены только продольные элементы (Toyoda et al., 2005(Toyoda et al., , 2006. Перизониум служит своего рода формой, в которой откладываются створки инициальной клетки, и тем самым задаются ее очертания. ...
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... At least 300 diatoms were counted in each sample with an optical microscope at 1000 Â using oil immersion. Diatom species were identified based on Krammer and Lange-Bertalot (1986, 1988, 1991a, Round et al. (1990), Krammer (2000), Witkowski et al. (2000), Nagumo (2003), Sawai and Nagumo (2003a, b), Watanabe et al. (2005), Kobayashi et al. (2006), and Idei et al. (2012). ...
