82
2. Sterols
magellanicus, where it occurs to the extent of 1.2% in a mixture of at least
eleven sterols, by a combination of preparative thin-layer chromatography on
silver nitrate impregnated silica gel plates and preparative glc. Its structure
was secured by spectral methods. It will be recalled that the same group
isolated the unusual C 26 sterol (Section A) from the same Atlantic mollusk.
30
\ 29
28
ίΐ
40
F. Sterol Biosynthesis
Although sterol biosynthesis has been a lively topic for research and discussion (for a pertinent review see, e.g., Clayton, 1965), the specific problem of
marine sterol biosynthesis has been essentially neglected. Nomura et al.
(1969a) carried out tracer experiments on the holothurian Stichopus japonicus.
These investigators found that the animal did not incorporate labeled acetate
into sterols or triterpenoids. Only squalene carried a label.
In a companion experiment Nomura et al. (1969b) investigated the unsaponifiable fraction of the holothurians Stichopus japonicus and Holothuria
tubulosa and detected Δ
5 - and A
7 -sterols with 27, 28, and 29 carbon atoms.
More interestingly from a biogenetic standpoint, the authors report the
presence of the triterpenoids cycloartenol and lanosterol in the sea cucumbers.
In a related observation Gibbons et al. (1968) report the possible occurrence
of cycloartenol, 24-methylenecycloartenol as well as 24-ethylidene and 24methylenelophenol in the green algae Enteromorpha intestinalis and Ulva
lactuca.
In contrast with the negative incorporation results of Nomura et al
(1969a), Fagerlund and Idler (1960) were able to isolate radioactive digitoninprecipitable material, presumably sterols, from the mussel Mytilus californianus and the clam Saxidomus giganteus after feeding experiments with acetate
labeled with carbon-14 at C-2.
In an unrelated experiment the same researchers (Fagerlund and Idler,
1960) showed by feeding radiocholesterol (414
C) to the sea star Pisaster
ochraceus that this echinoderm is capable of transforming a Δ
5 - to a Δ
7 -
sterol.
2. Sterols
magellanicus, where it occurs to the extent of 1.2% in a mixture of at least
eleven sterols, by a combination of preparative thin-layer chromatography on
silver nitrate impregnated silica gel plates and preparative glc. Its structure
was secured by spectral methods. It will be recalled that the same group
isolated the unusual C 26 sterol (Section A) from the same Atlantic mollusk.
30
\ 29
28
ίΐ
40
F. Sterol Biosynthesis
Although sterol biosynthesis has been a lively topic for research and discussion (for a pertinent review see, e.g., Clayton, 1965), the specific problem of
marine sterol biosynthesis has been essentially neglected. Nomura et al.
(1969a) carried out tracer experiments on the holothurian Stichopus japonicus.
These investigators found that the animal did not incorporate labeled acetate
into sterols or triterpenoids. Only squalene carried a label.
In a companion experiment Nomura et al. (1969b) investigated the unsaponifiable fraction of the holothurians Stichopus japonicus and Holothuria
tubulosa and detected Δ
5 - and A
7 -sterols with 27, 28, and 29 carbon atoms.
More interestingly from a biogenetic standpoint, the authors report the
presence of the triterpenoids cycloartenol and lanosterol in the sea cucumbers.
In a related observation Gibbons et al. (1968) report the possible occurrence
of cycloartenol, 24-methylenecycloartenol as well as 24-ethylidene and 24methylenelophenol in the green algae Enteromorpha intestinalis and Ulva
lactuca.
In contrast with the negative incorporation results of Nomura et al
(1969a), Fagerlund and Idler (1960) were able to isolate radioactive digitoninprecipitable material, presumably sterols, from the mussel Mytilus californianus and the clam Saxidomus giganteus after feeding experiments with acetate
labeled with carbon-14 at C-2.
In an unrelated experiment the same researchers (Fagerlund and Idler,
1960) showed by feeding radiocholesterol (414
C) to the sea star Pisaster
ochraceus that this echinoderm is capable of transforming a Δ
5 - to a Δ
7 -
sterol.