428
U. B. OOWEY AND J. R. SBRQENT
the patterns from freshwater and marine fish in that the former
contain elevated levels of 18 : 2w6 and 18 : 3w3 acids. It is of considerable interest that the overall fatty acid composition of phospholipids
TABLE Xm. DISTRIBUTION OB MAJOR FATTY ACIDS IN FISH
PHOSPHOLIPIDS
Salmona
Lecithin
Menhadena
Lecithin
14:O
16:O
16:l
l8:O
18:l
18:2
18:3
20:4
20:6
22:6
22:6
0.7
8.0
2.0
6.7
22
-
1.0
12
43
-
0.6
46
-
3.2
7.4
1.0
2.2
-
13
-
28
Tunas Phospholipid ofb
Cod
s o w
lipid
lipid
Lecithin
sweet smelt
Phospho- PhosphoWild Cultivated
0-7
1.4
0.8
0.6
1.0
2.1
6.6
2.7
1.6
2.9
6.0
9.0
9-6
4.2
6.1
7.6
16.6
16.9
10.1
9.3
0.7
4.6
4.7
0.8
-
0.8
6.2
6.0
-
-
2.7
3.6
1.0
2.9
6.4
7-1
6.6
6.2
14.6
17.3
-
4.7
2.6
1.2
9.3
66
19.0
28.4
36.4
21.2
19
23
24
21
20
(I, Data from MenzelI and Olaott (1964); b, data from Shimma and Taguchi (1964);
data from Olley and Duncan (1966); all expressed aa weight % fatty acids;
(-) eignifles a;bsent or present in trme amounts.
from cultivated smelt is very similar to that in the wild fish indicating
that cultivation has not altered significantly tissue phospholipids. The
marked extent to which the polyunsaturated fatty acids are accumulated in phospholipids indicates their important role in the structural
maintenance and function of cellular membranes. The extremely high
content of polyunsaturated fatty acids in the intracellular membranes
of fish is undoubtedly related to the requirement of poikilothermic
animals to maintain membrane fluidity at low temperatures. This
consideration is of lesser importance in triglycerides where the more
saturated fatty acids are concerned largely with energy provision.
2. Environmental factors
The above discussion is based on the analyses of oils and lipids from
large numbers of individual fish, and frequently from pooled samples of
oils. At the levels of individual fish, environmental factors are likely
to cause pronounced alterations in the general patterns of fatty acids.
For example Lewis (1962, 1967) has analyaed various species of fish and
crustaceans caught at different depths in the ocean down to 4 400 m.
U. B. OOWEY AND J. R. SBRQENT
the patterns from freshwater and marine fish in that the former
contain elevated levels of 18 : 2w6 and 18 : 3w3 acids. It is of considerable interest that the overall fatty acid composition of phospholipids
TABLE Xm. DISTRIBUTION OB MAJOR FATTY ACIDS IN FISH
PHOSPHOLIPIDS
Salmona
Lecithin
Menhadena
Lecithin
14:O
16:O
16:l
l8:O
18:l
18:2
18:3
20:4
20:6
22:6
22:6
0.7
8.0
2.0
6.7
22
-
1.0
12
43
-
0.6
46
-
3.2
7.4
1.0
2.2
-
13
-
28
Tunas Phospholipid ofb
Cod
s o w
lipid
lipid
Lecithin
sweet smelt
Phospho- PhosphoWild Cultivated
0-7
1.4
0.8
0.6
1.0
2.1
6.6
2.7
1.6
2.9
6.0
9.0
9-6
4.2
6.1
7.6
16.6
16.9
10.1
9.3
0.7
4.6
4.7
0.8
-
0.8
6.2
6.0
-
-
2.7
3.6
1.0
2.9
6.4
7-1
6.6
6.2
14.6
17.3
-
4.7
2.6
1.2
9.3
66
19.0
28.4
36.4
21.2
19
23
24
21
20
(I, Data from MenzelI and Olaott (1964); b, data from Shimma and Taguchi (1964);
data from Olley and Duncan (1966); all expressed aa weight % fatty acids;
(-) eignifles a;bsent or present in trme amounts.
from cultivated smelt is very similar to that in the wild fish indicating
that cultivation has not altered significantly tissue phospholipids. The
marked extent to which the polyunsaturated fatty acids are accumulated in phospholipids indicates their important role in the structural
maintenance and function of cellular membranes. The extremely high
content of polyunsaturated fatty acids in the intracellular membranes
of fish is undoubtedly related to the requirement of poikilothermic
animals to maintain membrane fluidity at low temperatures. This
consideration is of lesser importance in triglycerides where the more
saturated fatty acids are concerned largely with energy provision.
2. Environmental factors
The above discussion is based on the analyses of oils and lipids from
large numbers of individual fish, and frequently from pooled samples of
oils. At the levels of individual fish, environmental factors are likely
to cause pronounced alterations in the general patterns of fatty acids.
For example Lewis (1962, 1967) has analyaed various species of fish and
crustaceans caught at different depths in the ocean down to 4 400 m.