Photosynthetic activity assessment in mixotrophically cultured Chlorella vulgaris biofilms at various developmental stages

The use of nanoparticles covers new spheres of production every year. Their release into the environment is possible at any stage of their lifespan: from the manufacturing process to the utilization in the final product; therefore potential risks they pose for various environmental objects should be evaluated. The purpose of this work was to assess the effect of technogenic nanoparticles on Chlorella vulgaris growth and photosynthetic activity. Toxic properties of three types of nanoparticles TiO2 with a size of 100 to 190 nm, SiO2 with dimensions of 10-15 nm and 100-120 nm have been studied. Chlorella vulgaris Beijer alga was used as test organism. The evaluation of nanoparticles toxicity was based on changes in the relative delayed fluorescence index (RDFI), which characterizes the photosynthetic activity of microalgae. The effect on the growth of the test culture was determined from the optical density (OD) of the algal suspension. It was found that the TiO2 nanoparticles slightly reduced the growth and activity of the cell photosynthetic apparatus. Large particles of SiO2 proved to be more toxic than smaller ones. For nanoparticles of 100-120 nm size , the EC50 value according to the OD index was 8 mg/dm3, while the particles measuring 10-15 nm did not show a significant effect on the growth of the culture. Large SiO2 particles also appeared more toxic than small particles, judging by RDFI parameter.

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The Heterotrophic Connection in a Photoautotrophic Chlorella Vulgaris Dominant in Wastewater Oxidation Ponds

Water Science & Technology ◽

10.2166/wst.1993.0546 ◽

1993 ◽

Vol 27 (7-8) ◽

pp. 151-155 ◽

Cited By ~ 6

Author(s):

Iris Cohen ◽

Anton F. Post

Keyword(s):

Chlorella Vulgaris ◽

Photosynthetic Activity ◽

Algal Growth ◽

Oxygen Demand ◽

Utilization Efficiency ◽

Direct Result ◽

Cellular Division ◽

Pigment Contents ◽

Photosynthetic Potential ◽

Oxidation Ponds

Chlorella vulgaris strain C1 was grown in laboratory under autotrophic and mixotrophic conditions. Cellular division rates increased in cultures supplied with either acetate or glucose. As a direct result respiratory activity was enhanced in those cells, most pronounced in the presence of acetate. Glucose and acetate had opposed effects on the photosynthetic activity of the cells. Cells grown in the presence of acetate had a 3-fold decrease in pigment contents. Since this was mostly expressed in decreased light utilization efficiency of the cells, we conclude that fewer light harvesting antennae were synthesised. Cells grown with glucose retain high pigment contents and photosynthetic activity of the cells was strongly enhanced. It was observed that even though organic matter may support algal growth in oxidation ponds, at the same time one may expect a much stronger oxygen demand accompanied by a reduced photosynthetic potential. This must be considered a burden on the wastewater treatment operation requiring countermeasures to be taken.

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Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005161x ◽

1974 ◽

Vol 32 ◽

pp. 320-321

Author(s):

J. P. Revel

Keyword(s):

Developmental Stages ◽

Three Dimensional ◽

Cell Movement ◽

Cellular Interactions ◽

Serial Sections ◽

Cell Sheets ◽

Freeze Etching ◽

Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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Electron investigations of rhabdovirus-like particles in mexican bean beetles and crickets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100082753 ◽

1978 ◽

Vol 36 (2) ◽

pp. 378-379

Author(s):

J. R. Adams ◽

G. J Tompkins ◽

A. M. Heimpel ◽

E. Dougherty

Keyword(s):

Biological Control ◽

Integrated Pest Management ◽

Pest Management ◽

Developmental Stages ◽

Management Program ◽

Acheta Domesticus ◽

Epilachna Varivestis ◽

House Cricket ◽

Similar Morphology ◽

Bean Beetle

As part of a continual search for potential pathogens of insects for use in biological control or on an integrated pest management program, two bacilliform virus-like particles (VLP) of similar morphology have been found in the Mexican bean beetle Epilachna varivestis Mulsant and the house cricket, Acheta domesticus (L. ).Tissues of diseased larvae and adults of E. varivestis and all developmental stages of A. domesticus were fixed according to procedures previously described. While the bean beetles displayed no external symptoms, the diseased crickets displayed a twitching and shaking of the metathoracic legs and a lowered rate of activity.Examinations of larvae and adult Mexican bean beetles collected in the field in 1976 and 1977 in Maryland and field collected specimens brought into the lab in the fall and reared through several generations revealed that specimens from each collection contained vesicles in the cytoplasm of the midgut filled with hundreds of these VLP's which were enveloped and measured approximately 16-25 nm x 55-110 nm, the shorter VLP's generally having the greater width (Fig. 1).

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The Fine Structure of the Sheath of Volvox Carteri f. Weismannia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079231 ◽

1977 ◽

Vol 35 ◽

pp. 346-347

Author(s):

Regina Birchem

Keyword(s):

Developmental Stages ◽

Ruthenium Red ◽

Sulfated Polysaccharides ◽

Volvox Carteri ◽

High Voltage Electron Microscopy ◽

Ultrastructural Studies ◽

Voltage Electron ◽

Sheath Formation ◽

And Inversion ◽

Sheath Material

Spheroids of the green colonial alga Volvox consist of biflagellate Chlamydomonad-like cells embedded in a transparent sheath. The sheath, important as a substance through which metabolic materials, light, and the sexual inducer must pass to and from the cells, has been shown to have an ordered structure (1,2). It is composed of both protein and carbohydrate (3); studies of V. rousseletii indicate an outside layer of sulfated polysaccharides (4).Ultrastructural studies of the sheath material in developmental stages of V. carteri f. weismannia were undertaken employing variations in the standard fixation procedure, ruthenium red, diaminobenzidine, and high voltage electron microscopy. Sheath formation begins after the completion of cell division and inversion of the daughter spheroids. Golgi, rough ER, and plasma membrane are actively involved in phases of sheath synthesis (Fig. 1). Six layers of ultrastructurally differentiated sheath material have been identified.

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