Correlations of plasma lipoproteins with LDL subfractions by particle size in men and women.

Nondenaturing gradient gel electrophoresis of plasma low density lipoprotein (LDL) has been used to identify major LDL subclasses that are influenced by genetic and other factors. In the present paper, this technique has been extended by measuring absorbance of lipid- or protein-stained gels as an index of concentration at intervals of 0.05 nm across the entire LDL particle size range (21.8-30 nm) in moderately overweight men (n = 115) and women (n = 78). When LDL absorbance levels were correlated with other lipoprotein variables, we found that the strengths of the correlations with each of triglycerides, apolipoprotein (apo) B, high density lipoprotein (HDL)2, and apoA-I achieve relative maximum values for two regions within the small LDL range (21-26 nm), one within LDL-IVB (22-23.2 nm) and a second within LDL-III (24.2-25.5 nm). We also found that the increase in LDL accompanying higher triglyceride levels occurs below 25.5 nm in men and between 24.5 and 26.5 nm in women, suggesting either that triglycerides are related to different LDL subclasses in men and women, or that particle sizes of metabolically homologous LDL subclasses may differ in men and women. As compared to analytic ultracentrifuge measurements, gradient gel measurements of LDL absorbance by the procedure described here provide greater resolution of LDL subclasses but less precision in estimating LDL levels.     

Polyoma virus minichromosomes: associated enzyme activities.

Polyoma minichromosomes were isolated and fractionated on glycerol gradients as described by Gourlie et al. (J. Virol. 38:805-814, 1981). Specific assays for DNa polymerases alpha, beta, and gamma, DNA topoisomerase I, and RNase H were carried out on each fraction. The number of units of activity in each fraction was compared with the number of total polyoma and replicative intermediate DNA molecules in each fraction determined by quantitative electron microscopy (M. R. Krauss and R. M. Benbow, J. Virol. 38:815-825, 1981). DNA polymerase alpha cosedimented with polyoma replicative intermediate DNA molecules. DNA polymerase beta and DNA topoisomerase I activities sedimented with mature polyoma minichromosomes. Although the bulk of RNase H activity sedimented in the minichromosome region, the peak of activity was found one fraction behind the peak of mature minichromosomes. Virtually no DNA polymerase gamma activity cosedimented with polyoma minichromosomes.     

Cooperative binding of fluorescein-labeled clupeine by DNA.

The alpha-amino group of clupeine fraction Z from herring sperm was coupled with fluorescein. Binding of the labeled protamine by DNA is accompanied by significant fluorescence quenching up to 80%. This allowed the convenient determination of the binding behavior of protamine and DNA. Binding was found to be strongly cooperative and not be significantly affected by the size of DNA. The ionic strength dependence in the range up to 0.3 M NaCl was rather small. Binding parameters were derived according to classical unique-site treatment and to a concept which includes vagrant multi-site binding.     

Absence of metabolic cooperation in PHA-stimulated human lymphocyte cultures

Intercellular communication as detected by ionic coupling and gap junction formation has been reported previously in phytohemagglutinin (PHA)-stimulated lymphocyte cultures. PHA-stimulated mixtures of normal and hypoxanthine phosphoribosyl-transferase (HPRT) deficient lymphocytes did not exhibit metabolic cooperation when incubated with [³H]hypoxanthine. These observations suggest that there may be selectivity for compounds transferred by lymphocyte junctions during intercellular communication.     

MASS CULTURE OF ALGAE FOR FOOD AND OTHER ORGANIC COMPOUNDS

Krauss, Robert W. (U. Maryland, College Park.) Mass culture of algae for food and other organic compounds. Amer. Jour. Bot. 49(4): 425–435. Illus. 1962.—Data are being collected which appear to support the use of unicellular algae for human food. Analyses of proteins, fats, carbohydrates, and vitamins indicate that unicellular green algae, especially Chlorella, should be excellent sources of these nutrients. The effectiveness of the algae for the support of growth of chickens, mice, rats, and rabbits has been found to be good. However, only limited studies have been done with humans. The problem of acceptability varies with the nationality of the subjects and the preparation of the food. Serious gaps still exist both in the technology of production and in the experimentation required to establish nutritional value. Nutrition studies using algae free of bacteria are urgently needed.     

Local and landscape responses of biodiversity in calcareous grasslands

Biodiversity and Conservation - Across Europe, calcareous grasslands become increasingly fragmented and their quality deteriorates through abandonment and land use intensification, both affecting...