Cholesterol and phospholipids content of yolk from fertilized and unfertilized hen eggs

Three lipid-containing (granules, low-density lipoproteins (LDL) and infranatant) of fertilized and unfertilized yolks were obtained from hen eggs, either from commercial sources or from Arbor acres henskept by the Pena Branca Aviario Pernambuco and utilized fresh (laid during the previous 7 days). Total cholesterol (TC) and total phospholipid (TP) levels (mg/g yolk, reported as means ñ SD) were determined. In the yolk granules (insoluble fraction) the levels of TC (2.05 ñ 0.36) and TP(0.90 ñ 0.43) of fertilized egg yolks were similar to the levels of TC (2.20 ñ 0.4) and TP (0.90 ñ 0.14) of unfertilized eggs. The levels TC in the LDL from fertilized egg yolks (8.29 ñ 1.63) were not statistically different from those in unfertilized eggs (7.31 ñ 1.50). In contrast, TC was not detected in the infranatant fraction of unfertilized egg yolks, but was present in the infranatant fraction (1.39 ñ 0.69) of fertilized eggs. The TP levels of LDL (0.73 ñ 0.23) and infranatant (0.32 ñ 0.09) fractions of fertilized egg yolks were significantly lower than the levels of TP in the LDL (1.73 ñ 0.51) and infranatant (0.79 ñ 0.59) fractions of unfertilized eggs. Consequently, the TC/TP ratio (mol/mol) increased in the LDL and infranatant fractions of fertilized egg yolks when compared to unfertilized egg yolks. TC levels were similar in the total yolks TC levels were similar in the total yolk of fertilized (10.76 ñ 1.32) and unfertilized (10.33 ñ 1.77) eggs, while the TP levels were significantly lower in the fertilized (1.92 ñ 0.17) than in unfertilized (3.43 ñ 0.97) eggs. These results suggest a transfer of TC from the LDL to the infranatant fraction and a large consumption of TP during the fertilization process

Effect of experimental Schistosomiasis on 14C-4-cholesterol esterification by mouse liver homogenate

The effect of experimental schistosomiasis mansoni on cholesterol esterification by mouse liver homogenate was studied using 14C-4-cholesterol. The reaction was carried out in 0.85 ml containing 10 nCi labelled cholesterol (I64 nmol as an albumin-stabilized emulsion) with 30 mg tissue homogenate in 176 mM sodium phosphate buffer, pH 7.1, containing 59 micronM oleic acid, 0.3 mM CoASH and 8.8 mM ATP. In experiments with liver from infected mice(N = 22), the percentage of cholesterol esterification was 6.9 + or - 0.7%/h. This rate was 52% less than that observed in normal mice (14.4 + or - 0.6%/h, N = 21). The decrease may be due to the existence of inhibitors of the cholesterol esterifying in the infected liver, increased hydrolysis of cholesteryl esters or a decrease in the synthesis of the enzyme acyl CoA:cholesterol acyl transferase by the infected liver