The effect of crude oil on the morphology of the green flagellate Chlamydomonas angulosa

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Abstract
The morphological changes of C. angulosa induced by treatment with an aqueous crude oil extract (ACOE) were studied and compared with normal cells in the exponential phase of growth. Observations of oil-treated cells under the light microscope showed an effect on flagellar length and on motility, an increased activity of the contractile vacuoles, and an increase in granulations. Cells so treated become surrounded by a transparent envelope. By EM, the progression of ultrastructural changes was followed. These changes include a widened space between the cell wall and the plasmalemma, distorted and disorganized chloroplast lamellae, a decrease in density of the osmiophilic granules, and the presence of electron-dense deposits inside the cytoplasmic vacuoles. Cells possessed the ability to recover from the above abnormalities within an 8 day incubation period. Such a recovery corresponded to resumption of motility, capacity for growth and photosynthesis. Based both on appearance, and on comparisons with bacterial, fungal studies and cytochemical studies, it is suggested that the osmiophilic granules are lipid in nature and may act as a hydrocarbon sink. A self-cleansing mechanism is also suggested for these granules.