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Oogamous reproduction, with two-step auxosporulation, in the centric diatom Thalassiosira punctigera (Bacillariophyta)
Chepurnov, V.A.; Mann, D.G.; von Dassow, P.; Armbrust, E.V.; Sabbe, K.; Dasseville, R.; Vyverman, W. (2006). Oogamous reproduction, with two-step auxosporulation, in the centric diatom Thalassiosira punctigera (Bacillariophyta). J. Phycol. 42(4): 845-858. dx.doi.org/10.1111/j.1529-8817.2006.00244.x
In: Journal of Phycology. Blackwell Science: New York. ISSN 0022-3646, more
Peer reviewed article  

Available in Authors 
    VLIZ: Open Repository 225256 [ OMA ]

Keywords
    Mating; Sexual reproduction; Bacillariophyceae [WoRMS]; Thalassiosira P.T. Cleve, 1873 [WoRMS]; ANE, Netherlands, Westerschelde, Terneuzen [Marine Regions]; Marine
Author keywords
    auxosporulation; centric diatoms; inbreeding; life cycle; mating; oogamy; sexual reproduction; Thalassiosira

Authors  Top 
  • Chepurnov, V.A., more
  • Mann, D.G., more
  • von Dassow, P.
  • Armbrust, E.V.

Abstract
    Thalassiosira species are common components of marine planktonic communities worldwide and are used intensively as model experimental organisms. However, data on life cycles and sexuality within the genus are fragmentary. A clone of the cosmopolitan marine diatom Thalassiosira punctigera Cleve emend. Hasle was isolated from the North Sea and oogamous sexual reproduction was observed in culture. Cells approximately 45 µm and smaller became sexualized. Oogonia were produced preferentially and spermatogenesis was infrequent. Unfertilized oogonia always aborted and their development was apparently arrested at prophase of meiosis I. Further progression through meiosis and auxospore formation occurred only after a sperm had penetrated into the oocyte. Many cells of the new large-celled generation (approximately 90–120 µm in size) immediately became sexualized again but only oogonia were produced. A few of the large oogonia became auxospores and produced initial cells 132–153 µm in diameter. The second step of auxosporulation probably involved fertilization of large-celled oocytes by the sperm of the small-celled spermatogonangia that were still present in the culture. An F1 clone obtained after selfing within the small-celled auxosporulation size range was investigated. Like the parent clone, the F1 clone was homothallic but no auxosporulation was observed: spermatogonangia were unable to produce viable sperm, apparently because of inbreeding depression. Aggregation and interaction of oogonia were documented, and may be relevant for understanding the mechanisms of signaling and recognition between sexualized cells and the evolution of sexuality in pennate diatoms.

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