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Link to original content: https://pubmed.ncbi.nlm.nih.gov/28152022
Cell reproductive patterns in the green alga Pseudokirchneriella subcapitata (=Selenastrum capricornutum) and their variations under exposure to the typical toxicants potassium dichromate and 3,5-DCP - PubMed Skip to main page content
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. 2017 Feb 2;12(2):e0171259.
doi: 10.1371/journal.pone.0171259. eCollection 2017.

Cell reproductive patterns in the green alga Pseudokirchneriella subcapitata (=Selenastrum capricornutum) and their variations under exposure to the typical toxicants potassium dichromate and 3,5-DCP

Takahiro Yamagishi  1 , Haruyo Yamaguchi  2 , Shigekatsu Suzuki  2 , Yoshifumi Horie  1 , Norihisa Tatarazako  1
Affiliations

Cell reproductive patterns in the green alga Pseudokirchneriella subcapitata (=Selenastrum capricornutum) and their variations under exposure to the typical toxicants potassium dichromate and 3,5-DCP

Takahiro Yamagishi et al. PLoS One. .

Abstract

Pseudokirchneriella subcapitata is a sickle-shaped freshwater green microalga that is normally found in unicellular form. Currently, it is the best known and most frequently used species of ecotoxicological bioindicator because of its high growth rate and sensitivity to toxicants. However, despite this organism's, our knowledge of its cell biology-for example, the patterns of nuclear and cytoplasmic division in the mitotic stage-is limited. Although it has been reported that P. subcapitata proliferates by popularity forming four daughter cells (autospores) through multiple fission after two nuclear divisions, here, we report two additional reproductive patterns by which two autospores are formed by binary fission ("two-autospore type") and eight autospores are formed by multiple fission ("eight-autospore type"). Moreover, we found that cell reproductive patterns differed markedly with the culture conditions or with exposure to either of two typical toxicants, potassium dichromate (K2Cr2O7) and 3,5-dichlorophenol (3,5-DCP). The eight-autospore type occurred at the highest frequency in the early phase of culture, but it disappeared under 3,5-DCP at 2.0 mg/L. Under 0.3 mg/L K2CrO7 (Cr(VI)) the eight-autospore type took substantially longer to appear than in control culture. The two-autospore type occurred only in the late phase of culture. To our knowledge, this is the first detailed evaluation of the reproductive patterns of P. subcapitata, which changed dramatically in the presence of toxicants. These findings suggest that observation of the reproductive patterns of P. subcapitata will help to elucidate different cell reactions to toxicants.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Maximum likelihood (ML) tree based on the plastid-encoded Rubisco large subunit (rbcL).
Numbers on branches indicate bootstrap values (1,000 replicates) from ML analysis. Only bootstrap values >50% are shown.
Fig 2
Fig 2. Cell reproductive patterns in Pseudokirchneriella subcapitata, focusing on cytoplasmic and nuclear division.
Cells were observed by differential interference contrast microscopy (a1-q1) or DAPI staining (a2-q2). Three reproductive patterns were found in the population 72 h after the beginning of culture, namely the four-autospore type (a-j), the two-autospore type (k and l), and the eight-autospore type (m-o). Also shown are cells with cleavage furrows around the nuclei (p) and a cell with a single giant nucleus (q). Arrows in (k1) and (l1) indicate the wall of the parental cell. Scale bars in (a1), (m1), (p1), and (q1), 10 μm. Scale bar in (a1) applies to (b-l). Scale bar in (m1) also applies to (n and o).
Fig 3
Fig 3. Effects of Cr(VI) and 3,5-DCP on cell density and size.
Pseudokirchneriella subcapitata was exposed to Cr(VI) (a and b) or 3,5-DCP (b and d), and the cell density (a and c) and diameter (b and d) were measured every 24 h. In (a and b), red (open circle), control; blue (open triangle), Cr(VI) 0.15 mg/L; green (open square) 0.3 mg/L Cr(VI). In (b and d), red, control; blue, 2.0 mg/L 3,5-DCP; green 4.0 mg/L 3,5-DCP. Note that the cell sizes measured by the electronic particle counter differ from the sizes shown in Fig 1 because cell size of P. subcapitata is different in longitudinal and transvers axis. Error bars denote standard deviations with 95% confidence limits.
Fig 4
Fig 4. Frequency distributions of different cell reproductive patterns in Pseudokirchneriella subcapitata in the presence of Cr(VI) or 3,5-DCP.
Observation frequencies of cells of the two-, four-, or eight-autospore type were measured by staining with DAPI every 24 h until 120 h after the start of exposure to Cr(VI) (a) or 3,5-DCP (b). Although single nuclear cells were not counted, it is equal to the remains of total frequencies of the two-, four-, or eight-autospore type. Data are means of five independent experiments. Error bars denote standard deviations with 95% confidence limits.
Fig 5
Fig 5. Cells of Pseudokirchneriella subcapitata of the eight-autospore type in the presence of Cr(VI).
Cells were observed by differential interference contrast microscopy (a1-d1) or DAPI staining (a2-d2). (a), multinucleated cell with four nuclei; (b and c), multinucleated cells with eight nuclei; and (d), eight autospores in a parental cell. Scale bar in (a1), 10 μm. Scale bar in (a1) applies to (b-d).
Fig 6
Fig 6. Diagrammatic representation of different cell reproductive patterns found in Pseudokirchneriella subcapitata.
Three cell reproductive types were observed: a two-autospore type (b0-b2); a four-autospore type (c0-c2) (most frequently observed in the population in the 72 h after the start of culture), in which cytokinesis occurs by repeated binary fission after two nuclear divisions; and an eight-autospore type (d0-d2), in which autospore formation begins with separation of the cytoplasm into eight compartments, not by repeated binary fission as in the four-autospore type. The giant nucleus—type cell may also proceed to eight-autospore formation after multinucleation by three nuclear divisions. (c2) and (d2) also may occur as part of eight-autospore formation when the cell cycle restarts without the release of autospores.
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References

    1. Nygaad G, Komárek J, Kristiansen J, Skulberg OM. Taxonomic designations of the bioassay alga NIVA-CHL1 ("Selenastrum capricornum") and some related strains. Opera Botanica. 1987;90: 1–46.
    1. Hindák F. Studies on the chlorococcal algae (Chlorophyceae). V Biologické Práce. 1990;36: 1–227.
    1. Krienitz L, Bock C, Nozaki H, Wolf M. SSU rRNA gene phylogeny of morphospecies affiliated to the bioassay alga "Selenastrum capricornutum" recovered the polyphyletic origin of crescent-shaped Chlorophyta. J Phycol. 2011;47: 880–893. 10.1111/j.1529-8817.2011.01010.x - DOI - PubMed
    1. Machado MD, Soares EV. Modification of cell volume and proliferative capacity of Pseudokirchneriella subcapitata cells exposed to metal stress. Aquatic Toxicol. 2014;147: 1–6. - PubMed
    1. Franklin NM, Stauber JL, Lim RP. Development of flow cytometry-based algal bioassays for assessing toxicity of copper in natural waters. Environ Toxicol Chem. 2001;20: 160–170. - PubMed

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