dynamics of sexual phase in the marine diatom Pseudo‐nitzschia multistriata (Bacillariophyceae)
Sexual reproduction represents a fundamental phase in the life cycle of diatoms, linked to both the production of genotypic diversity and the formation of large‐sized initial cells. Only cells below a certain size threshold can be sexualized, but various environmental factors can modulate the succes...
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| Published in: | Journal of phycology Vol. 50; no. 5; pp. 817 - 828 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
United States
Phycological Society of America
01-10-2014
Blackwell Publishing Ltd Wiley Subscription Services, Inc |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Sexual reproduction represents a fundamental phase in the life cycle of diatoms, linked to both the production of genotypic diversity and the formation of large‐sized initial cells. Only cells below a certain size threshold can be sexualized, but various environmental factors can modulate the success of sexual reproduction. We investigated the role of cell density and physiological conditions of parental strains in affecting the success and timing of sexual reproduction in the marine heterothallic diatom Pseudo‐nitzschia multistriata. We also studied the dynamics of the sexual phase in still conditions allowing cell sedimentation and in gently mixed conditions that keep cells in suspension. Our results showed that successful sexual reproduction can only be achieved when crossing parental strains in the exponential growth phase. Evidence was provided for the fact that sexual reproduction is a density‐dependent event and requires a threshold cell concentration to start, although this might vary considerably amongst strains. Moreover, the onset of the sexual phase was coupled to a marked reduction in growth of the vegetative parental cells. The crosses carried out in physically mixed conditions produced a significantly reduced number of sexual stages as compared to crosses in still conditions, showing that mixing impairs sexualization. The results of our experiments suggest that the signaling that triggers the sexual phase is favored when cells can accumulate, reducing the distance between them and facilitating contacts and/or the perception of chemical cues. Information on the progression of the sexual phase in laboratory conditions help understanding the conditions at which sex occurs in the natural environment. |
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| Bibliography: | http://dx.doi.org/10.1111/jpy.12225 ark:/67375/WNG-PR85H6W6-F Stazione Zoologica Anton Dohrn istex:6A4003FA7236DF649CE7EB0F9329DABCC42B6F99 Figure S1. Schematic drawings illustrating the experimental set up of crosses carried out with Pseudo-nitzschia multistriata parental strains collected at different cell densities and growth phases.Figure S2. Light micrographs of different life cycle stages of Pseudo-nitzschia multistriata.Figure S3. Growth curves of Pseudo-nitzschia multistriata co-cultures started with parental strains collected at the same time points of their growth curve and diluted at different inoculum concentration (Experiment #3).Figure S4. Growth curves of Pseudo-nitzschia multistriata co-cultures started with parental strains collected at the same time points of their growth curve and diluted at different inoculum concentration (Experiment #3).Figure S5. Cell concentration (cells · mL−1) of Pseudo-nitzschia multistriata parental strains (black squares), the sexual stages (yellow circles: gametes; green circles: auxospores; violet circles: initial cells) and the large F1 cells (light blue circles) in co-cultures incubated in mixed (a) and in still (b) conditions (Experiment #5). Each point represents the average of triplicates counts; SD is represented with vertical lines.Figure S6. Estimated distance between adjacent Pseudo-nitzschia multistriata cells (Pm+, Pm−, and F1 generation are included) when cultures were incubated in mixed (a) and still (b) experimental conditions; note the different scale between (a) and (b).Table S1. Strains used in the different experiments: strain code and mating type (in parenthesis), isolation date and the average length of the apical axis (n = 20 cells) when experiments were carried out.Table S2. Nutrient concentrations (μmol · L−1) measured at different time points along the growth curve of Pm− strain MVR171.8 and Pm+ strain MVR171.1. For each time point, two replicate measurements are reported. ArticleID:JPY12225 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0022-3646 1529-8817 |
| DOI: | 10.1111/jpy.12225 |