264
R.G. Ackman
11.2. Discussion
11.2.1. Lipid Classes
Lipids are universal, but careful recovery for study needs to be promoted for both
freshwater (Herbes and Allen, 1983) and marine organisms (Roose and Smedes,
1996; Smedes and Thomasen, 1996). Space does not permit a critical review of
this subject, nor of minor but biochemically important lipid classes such as
tocopherols. The subject has recently been reviewed elsewhere (Ackman, 1993),
and despite objections to the use of chloroform, it is clear that chloroform!
methanol extracts such as the Bligh and Dyer (1959) system are preferred solvent
systems for total lipid recovery.
The major lipid classes of most aquatic animals are shown in Figure 11.1. The
phospholipids are both structural and functional elements of cell membranes, and
o
II
R-O-C-R
Phosphatidyl choline
(lecithin)
Phosphatidyl ethanolamine
(cephalin)
Triacylglycerol
Wax Ester
Free Fatty Acid
(PL)
(TG)
(WE)
(FFA)
FIGURE 11.1. Some of the more important lipid classes found in aquatic life forms. Free
fatty acids are, in fact, hardly observed in living animals but may be liberated from any of
the more complex lipids by postmortem enzymatic hydrolysis.