海産二極性中心珪藻<i>Pseudoleyanella lunata</i>におけるdiatotepumの観察を伴う形態学および系統学的研究  [in Japanese] Morphology and phylogeny of the marine bipolar centric diatom <i>Pseudoleyanella lunata</i> (Cymatosiraceae) with special reference to the diatotepum  [in Japanese]

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Abstract

<p><i>Pseudoleyanella lunata </i>Takanoは背腹性の被殻を持つCymatosira科に属する海産種である。本研究では,<i>P. lunata</i>を,その生活環を通して詳細に観察し,細胞分裂に伴う葉緑体の挙動,殻の形成過程,細胞サイズの変化に伴う形質の安定性と変異を明らかにした。殻形はサイズが減少すると,背腹性が弱くなり,最後には円形になった。小型の細胞では帯面観は長方形であったが,増大胞子形成後の長大な被殻では<i>Leyanella</i>と同じように帯面観が屈曲していた。しかし,生活環を通して糸毛,管状突起は形成されなかった。分子系統解析では,Cymatosira科の中で<i>P. lunata</i>と<i>L. arenaria</i>は姉妹種として示された。また,本研究では被殻を裏打ちするdiatotepumの全形を観察した。Diatotepumは半被殻全体を裏打ちする袋状の構造体であり,トルイジンブルー水溶液によって染色された。透過型電子顕微鏡(TEM)観察では,殻面を裏打ちする部位で胞紋の模様と一致する高電子密度の点状紋様が,また,半殻帯を裏打ちする部位では各帯片の内側の縫い目と一致する線状の紋様が観察された。</p>

<p><i>Pseudoleyanella lunata</i> Takano is a marine diatom with dorsiventral valves belonging to the family Cymatosiraceae. We studied the range of variation in valve morphology throughout the life cycle. We also observed the chloroplast division of this species. In large cells, the valves were narrowly lanceolate, slightly capitate at the apices, and asymmetrical with respect to the apical plane, i.e. with almost straight and convex margins on the ventral and dorsal sides, respectively. During cell size reduction, the valves gradually lost their dorsiventral nature, and eventually became almost circular. Although <i>P. lunata</i> was rectangular in girdle view in small cells, large vegetative cells, particularly those generated soon after auxosporulation, were slightly bent, as in <i>Leyanella</i> Hasle <i>et al.</i> However, in contrast to <i>Leyanella</i>, <i>P. lunata</i> lacked both pili and tubular processes at all stages of its life cycle. In phylogenetic analyses (SSU rDNA and <i>rbc</i>L), <i>P. lunata</i> was sister to <i>Leyanella</i>. We also observed the whole structure of the diatotepum which was a sheet-like structure underlying each theca. Under the transmission electron microscope, dot-like marks with high electron density were observed: their position and pattern corresponded to valve poroids. In addition, the diatotepum bore electron-dense lines corresponding to the internal sutures between the girdle bands.</p>

Journal

  • Diatom

    Diatom 32(0), 1-10, 2016

    The Japanese Society of Diatomology

Codes

  • NII Article ID (NAID)
    130006940873
  • Text Lang
    JPN
  • ISSN
    0911-9310
  • Data Source
    J-STAGE 
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