282
R.G. Ackman
critical to some stages of metamorphosis in invertebrates, and the polyunsaturates
of these two families ((06. (03) may be, to some extent, interchangeable in phospholipids of both freshwater (e.g., Penaeus monodon; Merican and Shim, 1996)
or marine (e.g., the clam Chlamys islandica or the starfish Ctenodiscus crispatus;
Bell and Sargent. 1985) invertebrates. However, as non structural free acids they
are important in competing for enzymes to produce either of two families of
eicosanoids (Lands, 1986). These biochemicals are powerful agents in all animals.
Unfortunately, methods for their analysis are more suitable to larger organisms or
cell cultures (Tocher et aI., 1996).
/so- and anteiso-fatty acids of Figure 11.3. usually CIS and C 17 , may be of little
interest in most situations, although there are exceptions. They are present in all
animals, where an amino acid skeleton replaces the first acetate in fatty acid
biosynthesis. However, bacteria may use these fatty acids in lipids instead of
polyunsaturated fatty acids, and so detritus feeders often show a typically higher
proportion of iso- and anteiso-1S:0 and 17:0. Generally, they are ::;O.S% of total
fatty acids in fish lipids and may usually be omitted from tables presenting fatty
acid compositions, as can the slightly more important straight-chain IS:O and 17:0
fatty acids. Among the exceptions, SO% of the fatty acids in the lipids of one
population of breeding marine amphipods Pontoporeia femorata are odd-chain
lengths, and these accumulate in the fatty acids of smelt (Osmerus mordax), which
prey on them (Paradis and Ackman, 1976). Other related species such as Pontoporeia ho.'.;i in Lake Michigan (Gauvin et aI., 1989; Gardner et aI., 1985) or P
femorata in the Baltic (Hill et aI., 1992) do not have high percentages of odd-chain
fatty acids. Cyclopropanoid fatty acids originating from bacteria may be obvious
in fish from marshes (Cosper and Ackman, 1983) but are of minor interest except
in rare circumstances such as in Lake Baikal in the deep-water organism
Acanthogammarus grewingkii (Rezanka and Dembitsky, 1994). Such exogenous
fatty acids could identify fish or fish fat origins (Ratnayake et aI., 1989). The role
of bacteria in symbiosis with higher organisms around hydrothermal vents has
recently led to several interesting observations on fatty acids in these exotic life
forms. The cyclopropane fatty acids, not shown in Figure 11.3 because they are
Ubiquitous in the bacteria world, were abundant (Fullarton et aI.. I 99Sa). The
NMID (nonmethylene-interrupted dienoic acids) were plentiful in the unusual
tube worms Ridgeia piscesae. but the normal cis-methylene-interrupted polyunsaturated fatty acids of Figure 11.3 were also well represented (Fullarton et aI.,
1995b). NMIDs were also found in mussels collected near hydrocarbon seeps
(Fang et aI., 1993) and are probably more common than suspected in mollusk
lipids (Paradis and Ackman. 1977).
A summary of data for the CIS and longer chain polyunsaturated fatty acids
found in the energy reserves of five commercially important species found in
Canada's northern freshwater lakes is provided in Table II.S. Unpublished data of
McLeod and Ackman are supplemented by that for pike from Henderson et ai.
(l99Sb). The fish were of commercial size and were processed in Halifax. Usually, two to four fish were headed and the remaining whole bodies were homogenized; subsamples were then extracted in duplicate with CHCI 3 -MeOH by the
R.G. Ackman
critical to some stages of metamorphosis in invertebrates, and the polyunsaturates
of these two families ((06. (03) may be, to some extent, interchangeable in phospholipids of both freshwater (e.g., Penaeus monodon; Merican and Shim, 1996)
or marine (e.g., the clam Chlamys islandica or the starfish Ctenodiscus crispatus;
Bell and Sargent. 1985) invertebrates. However, as non structural free acids they
are important in competing for enzymes to produce either of two families of
eicosanoids (Lands, 1986). These biochemicals are powerful agents in all animals.
Unfortunately, methods for their analysis are more suitable to larger organisms or
cell cultures (Tocher et aI., 1996).
/so- and anteiso-fatty acids of Figure 11.3. usually CIS and C 17 , may be of little
interest in most situations, although there are exceptions. They are present in all
animals, where an amino acid skeleton replaces the first acetate in fatty acid
biosynthesis. However, bacteria may use these fatty acids in lipids instead of
polyunsaturated fatty acids, and so detritus feeders often show a typically higher
proportion of iso- and anteiso-1S:0 and 17:0. Generally, they are ::;O.S% of total
fatty acids in fish lipids and may usually be omitted from tables presenting fatty
acid compositions, as can the slightly more important straight-chain IS:O and 17:0
fatty acids. Among the exceptions, SO% of the fatty acids in the lipids of one
population of breeding marine amphipods Pontoporeia femorata are odd-chain
lengths, and these accumulate in the fatty acids of smelt (Osmerus mordax), which
prey on them (Paradis and Ackman, 1976). Other related species such as Pontoporeia ho.'.;i in Lake Michigan (Gauvin et aI., 1989; Gardner et aI., 1985) or P
femorata in the Baltic (Hill et aI., 1992) do not have high percentages of odd-chain
fatty acids. Cyclopropanoid fatty acids originating from bacteria may be obvious
in fish from marshes (Cosper and Ackman, 1983) but are of minor interest except
in rare circumstances such as in Lake Baikal in the deep-water organism
Acanthogammarus grewingkii (Rezanka and Dembitsky, 1994). Such exogenous
fatty acids could identify fish or fish fat origins (Ratnayake et aI., 1989). The role
of bacteria in symbiosis with higher organisms around hydrothermal vents has
recently led to several interesting observations on fatty acids in these exotic life
forms. The cyclopropane fatty acids, not shown in Figure 11.3 because they are
Ubiquitous in the bacteria world, were abundant (Fullarton et aI.. I 99Sa). The
NMID (nonmethylene-interrupted dienoic acids) were plentiful in the unusual
tube worms Ridgeia piscesae. but the normal cis-methylene-interrupted polyunsaturated fatty acids of Figure 11.3 were also well represented (Fullarton et aI.,
1995b). NMIDs were also found in mussels collected near hydrocarbon seeps
(Fang et aI., 1993) and are probably more common than suspected in mollusk
lipids (Paradis and Ackman. 1977).
A summary of data for the CIS and longer chain polyunsaturated fatty acids
found in the energy reserves of five commercially important species found in
Canada's northern freshwater lakes is provided in Table II.S. Unpublished data of
McLeod and Ackman are supplemented by that for pike from Henderson et ai.
(l99Sb). The fish were of commercial size and were processed in Halifax. Usually, two to four fish were headed and the remaining whole bodies were homogenized; subsamples were then extracted in duplicate with CHCI 3 -MeOH by the