Sites of accumulation and composition of hydrocarbons in Botryococcus braunii
Abstract
Raman spectrometry and electron microscopy show that, in the hydrocarbon-rich alga Botryococcus braunii, hydrocarbons accumulate in two distinct sites; internally in cytoplasmic inclusions and externally in successive outer walls and derived globules. No other classes of lipid are present in noticeable amounts in the cytoplasmic inclusions and in the external globules. The same hydrocarbons are observed in the internal and external pools but with different relative abundances, the shorter hydrocarbons being more abundant in the internal pool. The bulk of B. braunii hydrocarbons (ca 95%) is located in the external pool. Such an extracellular location allows this species to exhibit both an unusually high hydrocarbon content (15% of dry wt) and a normal level (0.75%) within the cells. The hydrocarbon pattern and location of B. braunii were compared with that of other organisms; a close relation appears between higher plant epidermal cells and this green alga. The trilaminar outer walls of B. braunii, at whose contact external hydrocarbon globules accumulate, contain a sporopollenin-like compound.
References (46)
- R.F. Cane
Geochm. Cosmochim. Acta
(1969) - A.G. Douglas et al.
Geochim. Cosmochim. Acta
(1969) - A.G. Douglas et al.
Geochim. Cosmochim. Acta
(1969) - R.F. Cane et al.
Geochim. Cosmochim. Acta
(1973) - J.R. Maxwell et al.
Phytochemistry
(1968) - A.C. Brown et al.
Phytochemistry
(1969) - E. Gelpi et al.
Phytochemistry
(1970) - B.A. Knights et al.
Phytochemistry
(1970) - R.D. Brandt et al.
Biochem. Biophys. Res. Commun.
(1969) - R. Renaud et al.
Phytochemistry
(1976)
Phytochemistry
Phytochemistry
Linit. Soc. N.S.W.
Bull. Soc. Hist. Nat. Autun
Bull. Soc. Hist. Nat. Autun
Rev. Gen. Bot.
Bull. Soc. Geol. (Fr.)
Trans. R. Soc. Edinburgh
Ann. Paleontol.
Micropaleontology
Trans. R. Soc. Edinburgh
J. Bot. Genève
Arch. Microbiol.
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