Variation in natural killer activity in peripheral blood during the menstrual cycle.

Natural killer activity was measured sequentially in normal female volunteers through their menstrual cycle. During the periovulatory period there was a significant fall in natural killer activity compared with in normal male volunteers. This variation was not apparent in women taking oral contraception. Cytotoxic activity was not related to oestradiol concentrations in individual women. The data support an interaction between immunological activity and sex hormones over the normal physiological range and would account for the described reduction in natural killer activity in pooled blood from female blood donors.     

Comparison of fatty acid content and DNA homology of the filamentous gliding bacteriaVitreoscilla,Flexibacter, Filibacter

DNA hybridization experiments showed that there was a high degree of homology amongVitreoscilla strains but not with DNA fromFilibacter limicola. Flexibacter spp were much more heterogeneous indicating a low genetic similarity. These results were also reflected in the membrane fatty acids of the bacteria. TheVitreoscilla strains were very similar with the 16:17c fatty acid being dominant. The membrane fatty acids ofF. limicola were dominated by a15:0 and a17:0 components which provided additional support for its relatedness to the genusBacillus. There was much greater diversity in the fatty acid patterns of theFlexibacter spp.F. aurantiacus, F. ruber andF. elegans shared the common dominant fatty acids 16:17c with theVitreoscilla strains, but this was replaced by the 16:16c acid inF. flexilis. F. ruber was distinguished by the absence of branched odd-chain monounsaturated fatty acids andF. elegans by the dominance of the -OH i15:0 acid. Precise determination of fatty acid double bond positions and geometry are essential for correct interpretation of increasingly complex ecological and taxonomic data sets.     

Bkm sequences are polymorphic in humans and are clustered in pericentric regions of various acrocentric chromosomes including the Y

Summary Probes of uncloned Bkm satellite DNA and a Drosophila clone 2(8), consisting mainly of GATA repeasts related to a major sequence component in Bkm, have been used to probe Southern blots of human male and female DNAs obtained from a Caucasian and an Australian aboriginal population and to human chromosomes in situ. Hybridization was observed to a distinct and an indistint series of bands against a smeared background. The same distinct bands are identified in the DNA samples with both probes, but are most readily detected using the uncloned Bkm probe. Most restriction bands are common to both populations and some are polymorphic. However, certain bands appear to be characteristic of the Australian aboriginal samples. There are no distinct sex-linked patterns. However all of the small acrocentric human chromosomes, including the Y chromosome show hybridization to uncloned Bkm in situ.     

Interaction of fatty acids with lipid bilayers

We present a method by which it is possible to describe the binding of fatty acids to phospholipid bilayers. Binding constants for oleic acid and a number of fatty acids used as spectroscopic probes are deduced from electrophoresis measurements. There is a large shift in $\text{p}\text{K}$ value for the fatty acids on binding to the phospholipid bilayers, consistent with stronger binding of the uncharged form of the fatty acid. For dansylundecanoic acid, fluorescence titrations are consistent with the binding constants derived from the electrophoresis experiments. For 12-(9-anthroyloxy)stearic acid, fluorescence and electrophoresis data are inconsistent, and we attribute this to quenching of fluorescence at high molar ratios of 12-anthroylstearic acid to phospholipid in the bilayer.     

Transformation of Clostridium acetobutylicum Protoplasts with Bacteriophage DNA

Techniques for the transformation of Clostridium acetobutylicum protoplasts with bacteriophage DNA are described. Transformation required regeneration of protoplasts and a 2-h eclipse period.     

Glycosyl acceptors in intact and permeabilized normal and cystic fibrosis fibroblasts

Using cell permeabilization, a technique which allows addition of exogenously supplied radiolabeled sugar nucleotides to serve as direct glycosyl donors, oligosaccharide biosynthesis was examined in fibroblasts obtained from normal and cystic fibrosis (CF) subjects. Incubation of logarithmically growing cells with either radiolabeled leucine or xylose has indicated that there was a difference in the synthetic rate between the cell types. Protein synthesis in normal cells made permeable with 50 m?g/ml lysolecithin (LL) was demonstrated to be absent, and could not be induced to take place by adding exogenous components, including energy sources and amino acids, normally required for protein synthesis. Thus radiolabeled sugars were being added to peptide acceptors which were already present at the time of LL addition. Both permeable and intact fibroblasts were exposed to labeled UDP-xylose, UDP-galactose, and UDP-glucuronic acid, all donors of mucopolysaccharide precursors. The uptake of xylose into protein was the same for both normal and CF cells, but permeable CF fibroblasts incorporated statistically greater amounts of sugar from UDP-galactose and UDP-glucuronic acid. Intact CF cells were also labeled using these two sugar nucleotides. Trypan blue exclusion indicated CF and normal fibroblasts were equally intact. This and the fact that preincubation of CF cells with the appropriate cold sugar nucleotide eliminated the differences in incorporation between the normal and CF cells suggested that CF fibroblasts had more cell surface acceptor than the normal cells.