Preferential incorporation of choline into the lipids of the nervous system of the housefly Musca domestica

The accumulation into the nervous system of a disproportionate amount of the phosphatidylcholine present in housefly larvae when reared on diets containing very low concentrations of choline is found to occur even when two analogues of choline, N-dimethylethylcholine (DMECh) or β-methylcholine (βMCh), are included in the diet at more than one hundred times the choline concentration. Both analogues are incorporated into phospholipids of the whole larvae and nervous system. The ratio of choline to analogue found in the lipids of the whole insect is 1 : 48 (DMECh) and 1 : 24 (βMCh) and in the nervous system 1 : 22 (DMECh) and 1 : 4 (βMCh). This preferential accumulation into the lipids also occurs during the development of the adult nervous system. The total phospholipid content of the head and thoracic ganglia of the adult is two to three times that of the fused larval ganglion. This results in 40 per cent of the phosphatidylcholine present in the adult fly, obtained from larvae fed on diets containing βMCh, being concentrated in the nervous system.