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Effect of mixotrophic growth on the ultrastructure and fatty acid composition of the diatom Synedra acus from Lake Baikal.

Shishlyannikov SM, Klimenkov IV, Bedoshvili YD, Mikhailov IS, Gorshkov AG - J Biol Res (Thessalon) (2014)

Bottom Line: Interest in studies concerning the effect of organic carbon sources on the growth of diatoms is largely aimed at subsequent physiological changes occurring in their cells.In this study, the results demonstrated that Synedra acus cells cultured in the presence of 80 mM glycerol contained lipid bodies of increased size, while cells from cultures supplemented with 40 mM glucose accumulated polysaccharide (chrysolaminarin) granules.Synedra acus subsp. radians have an ability to proliferate in the presence of high concentrations of organic substances and their transport into cells is evidence for its high adaptation potential, which, along with other factors, accounts for the dominance of this diatom in the spring-summer plankton of the oligotrophic Lake Baikal.

View Article: PubMed Central - PubMed

Affiliation: Limnological Institute, Siberian Branch, Russian Academy of Sciences, 3, Ulan-Batorskaya, St, P.O. Box 278, Irkutsk, 664033 Russia.

ABSTRACT

Background: Interest in studies concerning the effect of organic carbon sources on the growth of diatoms is largely aimed at subsequent physiological changes occurring in their cells. There are no data on structural changes in the cytoplasm and their relationship with changes in the composition of fatty acids in the course of mixotrophic culturing of freshwater diatoms. To elucidate the role of lipids in the growth of diatom cells in autotrophic and mixotrophic cultures, it is necessary to obtain information on the distribution of fatty acids among intracellular compartments and on possible ultrastructural changes in the cells.

Results: In this study, the results demonstrated that Synedra acus cells cultured in the presence of 80 mM glycerol contained lipid bodies of increased size, while cells from cultures supplemented with 40 mM glucose accumulated polysaccharide (chrysolaminarin) granules. An increase in the relative amounts of palmitic and stearic acids was revealed at the exponential growth phase of S. acus in the medium with 80 mM glycerol, which was indicative of the accumulation of fatty acids contained in triacylglycerols.

Conclusions: Synedra acus subsp. radians have an ability to proliferate in the presence of high concentrations of organic substances and their transport into cells is evidence for its high adaptation potential, which, along with other factors, accounts for the dominance of this diatom in the spring-summer plankton of the oligotrophic Lake Baikal.

No MeSH data available.


Related in: MedlinePlus

Fluorescence and transmission electron micrographs of Synedra acus cells. Yellow fluorescence of lipid bodies stained Nile Red dye and the red autofluorescence of chloroplasts (A), ultrastructural characteristics Synedra acus cells in autotrophic culture (B, E) and in mixotrophic cultures with glycerol (C, F) and glucose (D). Designations: Chl -chloroplast; V-vacuole with chrysolaminaran granules, m - mitochondria. N- nucleus. White arrows indicate lipid bodies. Scale bars: (A) - 10 μm, (C, D, E) - 500 nm, (B,F) - 2 μm.
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Fig3: Fluorescence and transmission electron micrographs of Synedra acus cells. Yellow fluorescence of lipid bodies stained Nile Red dye and the red autofluorescence of chloroplasts (A), ultrastructural characteristics Synedra acus cells in autotrophic culture (B, E) and in mixotrophic cultures with glycerol (C, F) and glucose (D). Designations: Chl -chloroplast; V-vacuole with chrysolaminaran granules, m - mitochondria. N- nucleus. White arrows indicate lipid bodies. Scale bars: (A) - 10 μm, (C, D, E) - 500 nm, (B,F) - 2 μm.

Mentions: According to the results of TEM, S. acus cells in autotrophic culture (Figure 3B) formed vacuoles (up to 1.0 μm) with homogeneous electron-dense contents, which could be located either at the periphery or in the center of the cell (Figure 3E). These vacuoles in preparations stained with Nile red were bright orange (Figure 3A), which was evidence for the lipid nature of their contents [40]. Such intracellular lipid bodies were also found in cells cultured under mixotrophic conditions (with glycerol or glucose). It should be noted, however, that the size of lipid bodies in cells from cultures with glycerol was greater than in cells from either autotrophic (control) or glucose-containing cultures, reaching 2.5 μm (Figure 3C and 3F). Such glycerol-dependent accumulation of lipids in the cytoplasm of diatoms was observed already at the phase of their exponential growth. Further enlargement of lipid inclusions at the stationary growth phase resulted in a increase in the overall cell volume, which was usually accompanied by deformation of the cell wall in the girdle zone (Figure 3F). At the stage of frustule formation, cells cultured in the presence of glucose contained a different kind of vacuoles (0.5-0.7 μm), which had heterogeneous granular and small-grained contents (10–20 nm, Figure 3D), and also included more electron-dense granules of a larger size (20–40 nm, Figure 3D). Such structures were not revealed in the cells cultured in autotrophic conditions and with glycerol. The characteristic structure of these organelles [41] could be regarded as evidence for the accumulation of polysaccharides (in particular, chrysolaminarin) in the cells.Figure 3


Effect of mixotrophic growth on the ultrastructure and fatty acid composition of the diatom Synedra acus from Lake Baikal.

Shishlyannikov SM, Klimenkov IV, Bedoshvili YD, Mikhailov IS, Gorshkov AG - J Biol Res (Thessalon) (2014)

Fluorescence and transmission electron micrographs of Synedra acus cells. Yellow fluorescence of lipid bodies stained Nile Red dye and the red autofluorescence of chloroplasts (A), ultrastructural characteristics Synedra acus cells in autotrophic culture (B, E) and in mixotrophic cultures with glycerol (C, F) and glucose (D). Designations: Chl -chloroplast; V-vacuole with chrysolaminaran granules, m - mitochondria. N- nucleus. White arrows indicate lipid bodies. Scale bars: (A) - 10 μm, (C, D, E) - 500 nm, (B,F) - 2 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389971&req=5

Fig3: Fluorescence and transmission electron micrographs of Synedra acus cells. Yellow fluorescence of lipid bodies stained Nile Red dye and the red autofluorescence of chloroplasts (A), ultrastructural characteristics Synedra acus cells in autotrophic culture (B, E) and in mixotrophic cultures with glycerol (C, F) and glucose (D). Designations: Chl -chloroplast; V-vacuole with chrysolaminaran granules, m - mitochondria. N- nucleus. White arrows indicate lipid bodies. Scale bars: (A) - 10 μm, (C, D, E) - 500 nm, (B,F) - 2 μm.
Mentions: According to the results of TEM, S. acus cells in autotrophic culture (Figure 3B) formed vacuoles (up to 1.0 μm) with homogeneous electron-dense contents, which could be located either at the periphery or in the center of the cell (Figure 3E). These vacuoles in preparations stained with Nile red were bright orange (Figure 3A), which was evidence for the lipid nature of their contents [40]. Such intracellular lipid bodies were also found in cells cultured under mixotrophic conditions (with glycerol or glucose). It should be noted, however, that the size of lipid bodies in cells from cultures with glycerol was greater than in cells from either autotrophic (control) or glucose-containing cultures, reaching 2.5 μm (Figure 3C and 3F). Such glycerol-dependent accumulation of lipids in the cytoplasm of diatoms was observed already at the phase of their exponential growth. Further enlargement of lipid inclusions at the stationary growth phase resulted in a increase in the overall cell volume, which was usually accompanied by deformation of the cell wall in the girdle zone (Figure 3F). At the stage of frustule formation, cells cultured in the presence of glucose contained a different kind of vacuoles (0.5-0.7 μm), which had heterogeneous granular and small-grained contents (10–20 nm, Figure 3D), and also included more electron-dense granules of a larger size (20–40 nm, Figure 3D). Such structures were not revealed in the cells cultured in autotrophic conditions and with glycerol. The characteristic structure of these organelles [41] could be regarded as evidence for the accumulation of polysaccharides (in particular, chrysolaminarin) in the cells.Figure 3

Bottom Line: Interest in studies concerning the effect of organic carbon sources on the growth of diatoms is largely aimed at subsequent physiological changes occurring in their cells.In this study, the results demonstrated that Synedra acus cells cultured in the presence of 80 mM glycerol contained lipid bodies of increased size, while cells from cultures supplemented with 40 mM glucose accumulated polysaccharide (chrysolaminarin) granules.Synedra acus subsp. radians have an ability to proliferate in the presence of high concentrations of organic substances and their transport into cells is evidence for its high adaptation potential, which, along with other factors, accounts for the dominance of this diatom in the spring-summer plankton of the oligotrophic Lake Baikal.

View Article: PubMed Central - PubMed

Affiliation: Limnological Institute, Siberian Branch, Russian Academy of Sciences, 3, Ulan-Batorskaya, St, P.O. Box 278, Irkutsk, 664033 Russia.

ABSTRACT

Background: Interest in studies concerning the effect of organic carbon sources on the growth of diatoms is largely aimed at subsequent physiological changes occurring in their cells. There are no data on structural changes in the cytoplasm and their relationship with changes in the composition of fatty acids in the course of mixotrophic culturing of freshwater diatoms. To elucidate the role of lipids in the growth of diatom cells in autotrophic and mixotrophic cultures, it is necessary to obtain information on the distribution of fatty acids among intracellular compartments and on possible ultrastructural changes in the cells.

Results: In this study, the results demonstrated that Synedra acus cells cultured in the presence of 80 mM glycerol contained lipid bodies of increased size, while cells from cultures supplemented with 40 mM glucose accumulated polysaccharide (chrysolaminarin) granules. An increase in the relative amounts of palmitic and stearic acids was revealed at the exponential growth phase of S. acus in the medium with 80 mM glycerol, which was indicative of the accumulation of fatty acids contained in triacylglycerols.

Conclusions: Synedra acus subsp. radians have an ability to proliferate in the presence of high concentrations of organic substances and their transport into cells is evidence for its high adaptation potential, which, along with other factors, accounts for the dominance of this diatom in the spring-summer plankton of the oligotrophic Lake Baikal.

No MeSH data available.


Related in: MedlinePlus