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R.G. Ackman
phatidylcholine, which was not initially present, and the triacylglycerols were
rearranged to provide highly unsaturated fatty acids, especially 22:60)3, for the
new phospholipids. Half of both the triacylglycerol and polar lipids originally
present were catabolized in one way or another. Similar lipid class modifications
have been shown to occur in herring roe and larvae (Tocher et aI., 1985), except
that phosphatidylcholine was the dominant polar lipid of all stages of development. Triacylglycerol proportions actually increased with egg development stage
and were not affected by hatching. Subsequently, they diminished, possibly as
fatty acids were needed for new phospholipids (see below).
In a study of the zooplankton available to vendace (Coregonus albula L.),
Linko et al. (1992) showed that in Lake Pyhajarvi the cladoceran Holopedium
gibberum was dominant in June, whereas Daphnia species were abundant in JUly.
Calanoid and cyclopoid copepods were important at all times from June to October. Wax esters were not found in either the plankton or the fish, but arachidonic
acid (20:40)6) made up 4-8% of the fatty acids of composite plankton samples,
accounting for the 2-4% of this fatty acid deposited in the triacylglycerols of the
vendace flesh. Similar proportions of this fatty acid were found in triacylglycerols
of fish from northern Canadian lakes (Ackman et aI., 1967). In cold-water marine
fish muscle, this fatty acid might be in the range of 0.1-0.5% triacylglycerol fatty
acids (Ackman, 1990; see also Table 11.5).
The Cladocera have, in fact, been intensively investigated for freshwater energy transfers. Lipid (oil) droplets have been observed and are reported as triacy Iglycerols (Goulden and Henry, 1984). Lipid reserves were tested in laboratory feeding experiments. Adult Cladocera with good lipid reserves could better
survive low-food situations, but not all species aggressively transferred lipid to
eggs in these situations. This process seemed to be limited in one smaller species,
possibly thus improving survival of the adults.
The least well-known lipid class of both freshwater and marine invertebrates is
acetone-mobile polar lipids (AMPL), first discussed by Parrish (1987). In his
classic paper on the Iatroscan TLC-FID method, he included chromatograms for
both marine (Bedford Basin, Nova Scotia) and freshwater (Lakes Huron and
Michigan) materials. In freshwater sediment trap samples and in those of Ponfoporeia hoyi, the then-unknown material (AMPL) was found to be an important
lipid class. More recently, another AMPL peak has been identified as partly
containing galactosyl and other plant lipid diacylglycerols (Parrish et aI., 1996b).
As AMPL is literally made up of "acetone-mobile polar lipids," it can include
chlorophyll and other pigments, so caution in identification and quantitation is
indicated. In respect to seston, another important dietary feed for marine bottom
dwellers, Parrish et al. (1995) have quantitated hydrocarbons, AMPL, sterols,
steryl and wax esters, triacylglycerols, free fatty acids, fatty alcohols, and even
phospholipids by TLC-FID analyses. This work illustrates perfectly why the
Iatroscan TLC-FID technology is used worldwide by aquatic scientists, including
in analyses reported in recent papers by freshwater invertebrate research groups
(Cavaletto et aI., 1996). Criticism has focused on the total lipid recovery calculated from TLC-FID results sometimes being about 10% less than that from
R.G. Ackman
phatidylcholine, which was not initially present, and the triacylglycerols were
rearranged to provide highly unsaturated fatty acids, especially 22:60)3, for the
new phospholipids. Half of both the triacylglycerol and polar lipids originally
present were catabolized in one way or another. Similar lipid class modifications
have been shown to occur in herring roe and larvae (Tocher et aI., 1985), except
that phosphatidylcholine was the dominant polar lipid of all stages of development. Triacylglycerol proportions actually increased with egg development stage
and were not affected by hatching. Subsequently, they diminished, possibly as
fatty acids were needed for new phospholipids (see below).
In a study of the zooplankton available to vendace (Coregonus albula L.),
Linko et al. (1992) showed that in Lake Pyhajarvi the cladoceran Holopedium
gibberum was dominant in June, whereas Daphnia species were abundant in JUly.
Calanoid and cyclopoid copepods were important at all times from June to October. Wax esters were not found in either the plankton or the fish, but arachidonic
acid (20:40)6) made up 4-8% of the fatty acids of composite plankton samples,
accounting for the 2-4% of this fatty acid deposited in the triacylglycerols of the
vendace flesh. Similar proportions of this fatty acid were found in triacylglycerols
of fish from northern Canadian lakes (Ackman et aI., 1967). In cold-water marine
fish muscle, this fatty acid might be in the range of 0.1-0.5% triacylglycerol fatty
acids (Ackman, 1990; see also Table 11.5).
The Cladocera have, in fact, been intensively investigated for freshwater energy transfers. Lipid (oil) droplets have been observed and are reported as triacy Iglycerols (Goulden and Henry, 1984). Lipid reserves were tested in laboratory feeding experiments. Adult Cladocera with good lipid reserves could better
survive low-food situations, but not all species aggressively transferred lipid to
eggs in these situations. This process seemed to be limited in one smaller species,
possibly thus improving survival of the adults.
The least well-known lipid class of both freshwater and marine invertebrates is
acetone-mobile polar lipids (AMPL), first discussed by Parrish (1987). In his
classic paper on the Iatroscan TLC-FID method, he included chromatograms for
both marine (Bedford Basin, Nova Scotia) and freshwater (Lakes Huron and
Michigan) materials. In freshwater sediment trap samples and in those of Ponfoporeia hoyi, the then-unknown material (AMPL) was found to be an important
lipid class. More recently, another AMPL peak has been identified as partly
containing galactosyl and other plant lipid diacylglycerols (Parrish et aI., 1996b).
As AMPL is literally made up of "acetone-mobile polar lipids," it can include
chlorophyll and other pigments, so caution in identification and quantitation is
indicated. In respect to seston, another important dietary feed for marine bottom
dwellers, Parrish et al. (1995) have quantitated hydrocarbons, AMPL, sterols,
steryl and wax esters, triacylglycerols, free fatty acids, fatty alcohols, and even
phospholipids by TLC-FID analyses. This work illustrates perfectly why the
Iatroscan TLC-FID technology is used worldwide by aquatic scientists, including
in analyses reported in recent papers by freshwater invertebrate research groups
(Cavaletto et aI., 1996). Criticism has focused on the total lipid recovery calculated from TLC-FID results sometimes being about 10% less than that from