284
R.G. Ackman
Bligh and Dyer (1959) procedure. Lipid classes were determined by the Iatroscan
TLC-FID techniques. For fatty acid analyses, total lipids were separated by plate
TLC; the triacylglycerols were recovered, the fatty acids converted to methyl
esters and then analyzed by capillary GLC as described elsewhere (Ackman,
1992; Polvi et aI., 1991), except that a DB-23 GLC column was used. All fish
were caught in one location (Matheson Island, Lake Winnipeg, Manitoba) in the
fall of 1994. The results show strong similarities, presumably related to the
sharing of a common food base in a large lake. Exceptions are readily observed,
such as the low level of 20:4(06 in the red sucker. The burbot shows a tendency to
elongate both (03 and (06 fatty acids to C 22 , leading to high levels of 22:5(06 and
22:6(03. These reproduce the results for tullibee and burbot oils from reduction of
commercial fish caught in Lake Winnipeg in the fall of 1965 (Ackman et aI.,
1967), except that in the 1965 tullibee oil 20:5(03 was 6.2% and 22:6(03 was 3.8%
of total triacylglycerols. Possibly this could relate to proportions offatty acids for
ovarian maturations as this is a fall spawner. The roe may be rich in phospholipid
22:6(03. The burbot may spawn in midwinter, but the low total fat of our samples
suggests lipid depletion. In 1965 fish, the analysis of oil showed 20:5(03 as 5.5o/c
and the 22:6(03 as 7.8%. The European pike liver was included, as this species is
also common in northern Canada. The general similarity among the polyunsaturated fatty acids shows that these are ubiquitous in cold freshwater milieus. The
differences in fatty acid composition from marine oils are often apparently minor
but can have important effects in terms of biochemistry (Innis et aI., 1995;
Josephson et aI., 1984).
11.2.5. Furan and Some Other Unusual Fatty Acids
Omitted from the table and figures are fatty acids containing a central furan ring
(Dembitsky et aI., 1993; Ishii et aI., 1988). Two freshwater phyla and species
(respectively, the crayfish Procambarus clarkii, the mollusk Anadonta piscinalis,
and the gastropod Limnaeafragilis) are only examples from the recent literature,
and furan fatty acids are well known in lipids of both freshwater fish (Sand et aI.,
1984; Ota and Takagi, 1983) and marine lipids (Ota and Takagi, 1990). They
occur in plants as well and are probably generated by lipoxygenases acting on
polyunsaturated fatty acids (Guth et aI., 1995). Very long-chain polyunsaturated
fatty acids such as 24:6(03, in this case marine in flounder lipids (Ota et aI., 1994),
are possibly of dietary origin. Such fatty acids are also found for lipids (depot fat)
of certain freshwater seals, as well as in a Baltic species (Kakela et aI., 1995).
Typical Ll5 marine polyunsaturated fatty acids are reported for sea urchins by
Takagi et al. (1986), but the freshwater sponges of Lake Baikal showed various
unusual long-chain (C 28 , C 29 , and C 30 ) polyunsaturated fatty acids with Ll5 ethylenic bonds (Dembitsky et aI., 1994). This universal Ll5 desaturation is of interest
as the cis-methylene interrupted 20:3(09 has a Ll5 bond and is widely considered a
sign of deficiency in polyunsaturated fatty acids in mammals. It can be induced in
fish under the same dietary stress (Webster et aI., 1994).
R.G. Ackman
Bligh and Dyer (1959) procedure. Lipid classes were determined by the Iatroscan
TLC-FID techniques. For fatty acid analyses, total lipids were separated by plate
TLC; the triacylglycerols were recovered, the fatty acids converted to methyl
esters and then analyzed by capillary GLC as described elsewhere (Ackman,
1992; Polvi et aI., 1991), except that a DB-23 GLC column was used. All fish
were caught in one location (Matheson Island, Lake Winnipeg, Manitoba) in the
fall of 1994. The results show strong similarities, presumably related to the
sharing of a common food base in a large lake. Exceptions are readily observed,
such as the low level of 20:4(06 in the red sucker. The burbot shows a tendency to
elongate both (03 and (06 fatty acids to C 22 , leading to high levels of 22:5(06 and
22:6(03. These reproduce the results for tullibee and burbot oils from reduction of
commercial fish caught in Lake Winnipeg in the fall of 1965 (Ackman et aI.,
1967), except that in the 1965 tullibee oil 20:5(03 was 6.2% and 22:6(03 was 3.8%
of total triacylglycerols. Possibly this could relate to proportions offatty acids for
ovarian maturations as this is a fall spawner. The roe may be rich in phospholipid
22:6(03. The burbot may spawn in midwinter, but the low total fat of our samples
suggests lipid depletion. In 1965 fish, the analysis of oil showed 20:5(03 as 5.5o/c
and the 22:6(03 as 7.8%. The European pike liver was included, as this species is
also common in northern Canada. The general similarity among the polyunsaturated fatty acids shows that these are ubiquitous in cold freshwater milieus. The
differences in fatty acid composition from marine oils are often apparently minor
but can have important effects in terms of biochemistry (Innis et aI., 1995;
Josephson et aI., 1984).
11.2.5. Furan and Some Other Unusual Fatty Acids
Omitted from the table and figures are fatty acids containing a central furan ring
(Dembitsky et aI., 1993; Ishii et aI., 1988). Two freshwater phyla and species
(respectively, the crayfish Procambarus clarkii, the mollusk Anadonta piscinalis,
and the gastropod Limnaeafragilis) are only examples from the recent literature,
and furan fatty acids are well known in lipids of both freshwater fish (Sand et aI.,
1984; Ota and Takagi, 1983) and marine lipids (Ota and Takagi, 1990). They
occur in plants as well and are probably generated by lipoxygenases acting on
polyunsaturated fatty acids (Guth et aI., 1995). Very long-chain polyunsaturated
fatty acids such as 24:6(03, in this case marine in flounder lipids (Ota et aI., 1994),
are possibly of dietary origin. Such fatty acids are also found for lipids (depot fat)
of certain freshwater seals, as well as in a Baltic species (Kakela et aI., 1995).
Typical Ll5 marine polyunsaturated fatty acids are reported for sea urchins by
Takagi et al. (1986), but the freshwater sponges of Lake Baikal showed various
unusual long-chain (C 28 , C 29 , and C 30 ) polyunsaturated fatty acids with Ll5 ethylenic bonds (Dembitsky et aI., 1994). This universal Ll5 desaturation is of interest
as the cis-methylene interrupted 20:3(09 has a Ll5 bond and is widely considered a
sign of deficiency in polyunsaturated fatty acids in mammals. It can be induced in
fish under the same dietary stress (Webster et aI., 1994).