1. Regulation of LCPUFA biosynthesis
A series of experiments designed to unravel the effects of
dietary PUFA consumption on the endogenous synthesis of DHA
from ALA have been conducted in rats, chickens and fish. The
results demonstrated the sensitivity of DHA accumulation to
dietary PUFA content, presumably because of inhibition of
the 6 desaturase. These studies will be extended to test whether
DHA accumulation was chiefly regulated via PUFA inhibition
of DHA synthesis or through PUFA inhibiting DHA incorporation
into membrane phospholipids.
To address the effect of PUFA on DHA biosynthesis we have
also initiated studies involving cloning of desaturase and
elongase genes. RT-PCR studies on the genes inserted into
yeast have established that although ALA inhibits the 6 desaturase,
the limiting step in the conversion of ALA to DHA, the effect
is not specific and all unsaturated fatty acids also act in
this way. Further studies are underway to assess the effect
of PUFA on incorporation of DHA into membrane phospholipids.
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