The effect of chicken erythrocyte High Mobility Group protein 1 (HMG-1) on the enzymatic hydrolysis of purified double-stranded and single-stranded bacteriophage lambda DNA was studied. HMG-1 was found to inhibit the digestion of single- and double-stranded DNA by S1 nuclease and DNase I, respectively. HMG-I increased the rate of hydrolysis of double-stranded DNA by micrococcal nuclease, particularly at low HMG-1/DNA ratios, and had little effect on the hydrolysis of single-stranded DNA by micrococcal nucleases, even at high HMG-1 DNA ratios. We also present a semi-quantitative estimate that HMG-1 and HMG-2 occur in chromatin from rapidly dividing, cultured rat hepatoma cells at about 8 times the level that they occur in adult rat liver chromatin.

Factors affecting the esterification in vitro of linoleate-1-14C by intact human erythrocytes were investigated. Lecithin contained the highest proportion of the esterified fatty acid, but it was not possible to detect any incorporation into the neutral lipids. Glucose caused a slight increase in incorporation into erythrocytes which had been stored for 18 h at 4°, but had little effect on fresh cells. Esterification was proportional to the intracellular nucleotide labile phosphate level (corresponding to the ATP and ADP levels), provided the latter was less than that found in fresh erythrocytes. However, no further increase in esterification occurred when the level of nucleotide labile phosphate was raised to twice that of fresh cells by incubation for 10 h with glucose and adenine. Water-immiscible phthalate esters, used for the separation of young and old erythrocytes, increased esterification two- to three-fold without altering either its correlation with the intracellular nucleotide labile phosphate level or the distribution of the linoleate-1-14C among the various phospholipids. The oldest 5% of the cell population, whether separated by phthalate esters or in Ringer solution, showed a diminished level of nucleotide labile phosphate and a decreased rate of esterification. The presence of glucose restored the level of linoleate-1-14C incorporation by old cells to that of the remainder of the cell population. Lysolecithin increased the rate of esterification without altering the distribution of the linoleate-14C among the phospholipids, and removed the difference between normal and energy-poor cells. These data suggest that the rate-limiting step in esterification may involve an energy-sensitive transport of free fatty acids into an intracellular precursor pool rather than the fatty acid esterification (thiokinase) reaction.

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Clones encoding the rice storage protein glutelin were selected from a cDNA library of immature rice seeds. Sequence analysis and hybridization studies on these clones provide insight into the nature of heterogeneity in glutelin genes. Based particularly on major differences in the 3'-noncoding regions, it appears that glutelin genes fall into two sub-families.