2. STEROLS: STRUCTURE AND DISTRIBUTION
133
much as 20% of ergosterol (I, R = F) and also some other unidentified
sterols (106).
VII. Sterols of Arthropods
A. STEROLS OF CRUSTACEANS AND MYRIAPODS
This phylum, so rich in species, embraces the Crustacea, Arachnoidea, Myriapoda, and Insecta. With but very few exceptions nothing is
known about the sterols of these animals. No systematic and comprehensive studies have been done on the comparative biochemistry of the
sterols of Crustacea, a class so abundant in readily accessible species.
Fragmentary observations point to a wide distribution of cholesterol
among representatives of many orders. In the subclass of Entomostraca,
cholesterol has been found in a brine shrimp of the primitive order of
Branchiopoda (107). Cholesterol has also been obtained from the oil of
Copepoda (108), from Cipridina of the order Ostracoda (109), and
from the barnacle, Balanus ghnduh, of the order Cirripedia (33). In
the subclass of Malacostraca, cholesterol appears to be the principal,
but not only, sterol of Ligia (syn. Ligyda) exotica (20), the common
small crustacean of the order Isopoda which lives above high-tide mark.
Cholesterol is the principal sterol of many if not all representatives of
the order Decapoda. Among the shrimps and prawns it has been isolated from Palaemon nipponensis (110) and from shrimp waste. The
latter material might some day become a commercial source of cholesterol (111). The Norway lobster, Nephrops norvegicus (112), the
freshwater crayfish, Cambarus clarkii (110), and such crabs as Carcinus
maenas, the green crab (6), Portunus plicatus (113), Eriphia spinifrons
(113), and Cancer magister (114), all contain cholesterol.
An unfortunate a priori assumption that cholesterol is the crustacean
sterol par excellence is probably responsible for the paucity of data.
What interesting and important discoveries may yet be made in this
field is best illustrated by recent work on barnacle sterols. This mixture
also consists largely, 60%, of cholesterol but contains in addition about
35% of 24-dehydrocholesterol (II, R = B) (33). This sterol is one of
the interesting final links in the chain of biosyntheses leading to
cholesterol. It had first been found in only very small quantities in the
chick embryo, and it had been named desmosterol (35). A careful and
near-quantitative study of the sterol mixtures of crustaceans may be
expected to reveal additional interesting sterols and to provide data
correlating the taxonomy and evolution of these animals to their sterol
content.
Much less is known about the sterols of the Arachnoidea, the
133
much as 20% of ergosterol (I, R = F) and also some other unidentified
sterols (106).
VII. Sterols of Arthropods
A. STEROLS OF CRUSTACEANS AND MYRIAPODS
This phylum, so rich in species, embraces the Crustacea, Arachnoidea, Myriapoda, and Insecta. With but very few exceptions nothing is
known about the sterols of these animals. No systematic and comprehensive studies have been done on the comparative biochemistry of the
sterols of Crustacea, a class so abundant in readily accessible species.
Fragmentary observations point to a wide distribution of cholesterol
among representatives of many orders. In the subclass of Entomostraca,
cholesterol has been found in a brine shrimp of the primitive order of
Branchiopoda (107). Cholesterol has also been obtained from the oil of
Copepoda (108), from Cipridina of the order Ostracoda (109), and
from the barnacle, Balanus ghnduh, of the order Cirripedia (33). In
the subclass of Malacostraca, cholesterol appears to be the principal,
but not only, sterol of Ligia (syn. Ligyda) exotica (20), the common
small crustacean of the order Isopoda which lives above high-tide mark.
Cholesterol is the principal sterol of many if not all representatives of
the order Decapoda. Among the shrimps and prawns it has been isolated from Palaemon nipponensis (110) and from shrimp waste. The
latter material might some day become a commercial source of cholesterol (111). The Norway lobster, Nephrops norvegicus (112), the
freshwater crayfish, Cambarus clarkii (110), and such crabs as Carcinus
maenas, the green crab (6), Portunus plicatus (113), Eriphia spinifrons
(113), and Cancer magister (114), all contain cholesterol.
An unfortunate a priori assumption that cholesterol is the crustacean
sterol par excellence is probably responsible for the paucity of data.
What interesting and important discoveries may yet be made in this
field is best illustrated by recent work on barnacle sterols. This mixture
also consists largely, 60%, of cholesterol but contains in addition about
35% of 24-dehydrocholesterol (II, R = B) (33). This sterol is one of
the interesting final links in the chain of biosyntheses leading to
cholesterol. It had first been found in only very small quantities in the
chick embryo, and it had been named desmosterol (35). A careful and
near-quantitative study of the sterol mixtures of crustaceans may be
expected to reveal additional interesting sterols and to provide data
correlating the taxonomy and evolution of these animals to their sterol
content.
Much less is known about the sterols of the Arachnoidea, the