Promotion of Sperm Formation of a Giant Diatom &lt;i&gt;Coscinodiscus wailesii&lt;/i&gt; GRAN by a Marine Bacterium

Nagai, Satoshi; Hori, Yutaka; Manabe, Takehiko; Imai, Ichiro

doi:10.2331/fishsci.60.625

Cited by 6 publications

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“…Direct stimulation of sexual reproduction of diatoms by bacteria was already reported by Nagai et al . (, ) and Nagai and Imai (). They found that spermatogenesis of the centric diatom Coscinodiscus wailesii Gran & Angst is induced by bacteria, a hint that bacteria indeed might externally trigger sexual reproduction and auxosporulation of diatoms.…”

Section: Discussionmentioning

confidence: 99%

Influence of bacteria on cell size development and morphology of cultivated diatoms

Windler

Bova

Kryvenda³

et al. 2014

Phycological Research

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SUMMARYVegetative cell division in diatoms often results in a decreased cell size of one of the daughter cells, which during long-term cultivation may lead to a gradual decrease of the mean cell size of the culture. To restore the initial cell size, sexual reproduction is required, however, in many diatom cultures sexual reproduction does not occur. Such diatom cultures may lose their viability once the average size of the cells falls below a critical size. Cell size reduction therefore seriously restrains the long-term stability of many diatom cultures. In order to study the bacterial influence on the size diminution process, we observed cell morphology and size distribution of the diatoms Achnanthidium minutissimum, Cymbella affiniformis and Nitzschia palea for more than two years in bacteria-free conditions (axenic cultures) and in cultures that contain bacteria (xenic cultures). We found considerable morphological aberrations of frustule microstructures in A. minutissimum and C. affiniformis when cultivated under axenic conditions compared to the xenic cultures. These variations comprise significant cell length reduction, simplification and rounding of the frustule contour and deformation of the siliceous cell walls, features that are normally found in older cultures shortly before they die off. In contrast, the xenic cultures were well preserved and showed less cell length diminution. Our results show that bacteria may have a fundamental influence on the stability of long-term cultures of diatoms.

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Section: Discussionmentioning

confidence: 99%

Influence of bacteria on cell size development and morphology of cultivated diatoms

Windler

Bova

Kryvenda³

et al. 2014

Phycological Research

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“…Recently, some bacteria that affect sexuality or growth of various marine phytoplankton have been isolated from natural marine environments. A bacterium that promotes sperm formation of the diatom Coscinodiscus wailesii Gran was isolated from sediment from Harima-Nada (Japan) (Nagai et al 1994). Sawayama et al (1993) reported that a bacterium inhibited the mating reaction of Alexandrium catenella.…”

Section: Discussionmentioning

confidence: 99%

Promotion of cyst formation in the toxic dinoflagellate Alexandrium (Dinophyceae) by natural bacterial assemblages from Hiroshima Bay, Japan

Adachi¹,

Kanno²,

Matsubara³

et al. 1999

Mar. Ecol. Prog. Ser.

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ABSTRACT:The relationship between the abundance of the toxic marine dinoflagellate Alexandrium tamarense (Lebour) Balech and Alexandrium-cyst-formation-promoting bacteria (Alex-CFPB) was investigated in the water column of Hiroshima Bay (Japan) from 1997 to 1998. Cell density of A. tamarense increased gradually from February to the middle of April, then peaked at the end of April and blooms declined rapidly in the beginning of May in both years. All seawater fractions collected from 5 m depth, where the density of A . tamarense cells was highest and which also contained the bulk of planktonic bacteria, promoted cyst formation of A. catenella (LVhedon and Kofoid) Balech. This promotion was not caused by effects from nutnent h t a t i o n . The number of Alex-CFPB in seawater samples, analyzed by means of the most probable number (MPN) method, increased from the beginning of the Alexandrium bloom and reached 3.60 X lo3 and 1.00 X 103 cells ml-' at the peak bloom period at the end of April in 1997 and 1998, respectively. As the blooms declined, the number of Alex-CFPB decreased rapidly to less than 10 cells ml-'. Alexandrium-cyst-formation-inhibiting bacteria (Alex-CFIB) were not detected. These results show a clear positive correlation between the abundance of A. tamarense and Alex-CFPB during blooms, which suggests that Alex-CFPB play a significant role in the process of encystment and bloom dynamics of Alexandrium in the field.

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“…A bacterium that promotes sperm formation of the diatom Coscinodiscus wailesii Gran was isolated from sediment from Harima-Nada (Japan) by Nagai et al (1994). They determined that the abundance of the bacterium in the sediments determined by MPN bioassay was about 10 4 cells ml -1 in the natural environment and concluded that the bacterium might play an important role in the process of sperm formation in the field (Nagai & Imai 1998).…”

Section: Natural Bacteria Affect Cyst Formation In Marine Phytoplanktonmentioning

confidence: 99%

Inhibition of cyst formation in the toxic dinoflagellate Alexandrium (Dinophyceae) by bacteria from Hiroshima Bay, Japan

Adachi¹,

Matsubara²,

Okamoto³

et al. 2002

Aquat. Microb. Ecol.

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ABSTRACT:The relationship between the abundance of the toxic marine dinoflagellate Alexandrium tamarense (Lebour) Balech and cyst formation-inhibiting bacteria (Alex-CFIB) was investigated in samples taken from the water column in Hiroshima Bay (Japan) in 1999. The cell density of A. tamarense peaked in the middle of April and blooms declined in May. Alex-CFIB were detected during the bloom period as well as the non-bloom period in 1999 by means of the most probable number (MPN) bioassay as well as the colony counting method. A total of 32 strains that had potential Alexandrium cyst formation-inhibiting activities (CFIB) were isolated from the seawater samples from Hiroshima Bay throughout the year. The population structure and genetic diversity of Alex-CFIB were analyzed by means of restriction fragment length polymorphism (RFLP) of the 16S ribosomal RNA genes (16S rDNA). Five ribotypes, Ia to Id and II types, were determined among the 32 strains of Alex-CFIB. Most of the strains belonged to ribotype I, suggesting that bacteria of ribotype I may be dominant in the Alex-CFIB assemblages in the field seawater. Almost the entire 16S rDNAbased phylogenetic tree showed that ribotypes I and II fell into the class Proteobacteria γ-subdivision Alteromonas group and theVibrio group, respectively. The 6-well microplate approach clarified that Alex-CFIB obtained in this study do not have growth-inhibiting activities, and Alex-CFIB of ribotype I (Alteromonas group) have strong activities of encystment inhibition among these ribotypes. The existence not only of Alexandrium cyst formation-promoting bacteria (Alex-CFPB) reported previously but also of Alex-CFIB in Hiroshima Bay throughout the year suggests that Alex-CFPB, as well as Alex-CFIB, especially bacteria of ribotype I, may play significant roles in the process of encystment and bloom dynamics of Alexandrium in the natural environment.KEY WORDS: Alexandrium · Dinoflagellate · Bacteria · Cyst Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 26: [223][224][225][226][227][228][229][230][231][232][233] 2001 It is important to elucidate the environmental factors that affect cyst formation in these toxic dinoflagellates in considering the production of cysts in their natural habitats. In laboratory cultures, sexuality of dinoflagellates has been reported to occur in response to stress following nitrogen and/or phosphorus depletion (Pfiester & Anderson 1987). There are, however, field reports of encystment under seemingly favorable nutrient conditions for growth. Anderson & Morel (1979), Anderson et al. (1983) and Perez et al. (1998) reported cyst formation for natural populations of Alexandrium tamarense in the presence of relatively high levels of nitrate and phosphate capable of supporting vegetative growth.Recently, we have focused on one of the possible biological factors, bacteria, that interact with toxic dinoflagellate Alexandrium. We clarified the existence of Alexandrium cyst formation-promoting bacteria (Alex-CFPB...

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Promotion of Sperm Formation of a Giant Diatom <i>Coscinodiscus wailesii</i> GRAN by a Marine Bacterium

Cited by 6 publications

References 0 publications

Influence of bacteria on cell size development and morphology of cultivated diatoms

Influence of bacteria on cell size development and morphology of cultivated diatoms

Promotion of cyst formation in the toxic dinoflagellate Alexandrium (Dinophyceae) by natural bacterial assemblages from Hiroshima Bay, Japan

Inhibition of cyst formation in the toxic dinoflagellate Alexandrium (Dinophyceae) by bacteria from Hiroshima Bay, Japan

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