Methyl motions in 13C-methylated concanavalin as studied by 13C magnetic resonance relaxation techniques

The carbon- 13 spin-lattice relaxation times and nuclear Overhauser enhancements of the N epsilon-monomethyllysine, N epsilon,N epsilon-dimethyllysine, and N alpha,N alpha-dimethylalanine resonances of 13C-methylated concanavalin A have been measured at three carbon frequencies and compared to the relaxation parameters predicted by several motional models. The experimental parameters cannot be reproduced by a simple dipolar relaxation model which includes isotropic reorientation of the protein plus free internal rotational diffusion of the methyl groups but are well predicted by a wobble in a cone model which includes isotropic reorientation of the protein at 33 ns, free internal rotational diffusion of the methyl groups, and a wobble diffusion which reflects the net motion of the amino acid side chains. The analysis indicates that the methylated epsilon-amino side chains exhibit only slightly more motional freedom than does the methylated N-terminal alpha-amino group and suggests some restriction of methyl group rotation in the dimethylamino residues.     

Assessment of DNA fingerprinting for determining genetic diversity in sheep populations

Genomic DNA, prepared from 12 animals from four sheep flocks, was digested with either HaeIII or Hin fI and probed with three DNA fingerprinting probes. Mean DNA fingerprint band sharing and band frequency calculated for each flock were used to estimate genetic diversity. Each of the DNA fingerprinting systems showed the same trend in diversity within the sampled flocks, and greater diversity between the flocks than within the flocks. DNA fingerprinting therefore provides a useful measure of genetic diversity in sheep.     

Cytokine production in a model of wound healing: the appearance of MIP-1, MIP-2, cachectin/TNF and IL-1

Macrophages are essential for normal wound repair and many of their effects on healing wounds are likely to be mediated by the secretion of cytokines. This study examines the appearance of messenger RNA (mRNA) for cachectin/tumor necrosis factor (TNF), IL 1, and macrophage inflammatory proteins 1 and 2 (MIP-1 and MIP-2), as well as the mature peptides, in a model of wound healing using wound chambers. RNA for all four cytokines can be detected in wound inflammatory cells by polymerase chain reaction amplification throughout the first 7 days. Cachectin/TNF and IL 1 protein levels peaked on the first day after wound chamber implantation, and MIP-1 and MIP-2 were detected only on day 3. The data suggest that these cytokines participate in the early inflammatory response to wounding.     

Polyacetylenes in Hawaiian bidens

Leaves and roots of 19 species and six subspecies of Hawaiian Bidens were examined for polyacetylenes. Eleven C₁₃ hydrocarbons, aromatic and thiophenyl derivatives, one C₁₄ tetrahydropyran and three C₁₇ hydrocarbons were isolated all identified. All can be derived from a common precursor, oleic acid. Polyacetylenes were not detected in the leaves of 13 taxa although they are found in the roots of all. The occurrence of 2-[2-phenyl-ethyne-1-yl]-5 acetoxymethyl thiopene in Bidens has not been previously reported. Its ubiquitous presence is consistent with other evidence that the Hawaiian species are all derived from a single ancestral immigrant to the islands. Most taxa could be distinguished by their complement of polyacetylenes in roots and leaves. No variation was found to occur within taxa except in B. torta, in which each population had a unique array of polyacetylenes. Above the species level there appeared to be no taxonomically significant pattern to the distribution of polyacetylenes in this group.     

The mode of action of polyacetylene and thiophene photosensitizers on liposome permeability to glucose

The mode of action of the two photosensitizers 1-phenylhepta-1,3,5-triyne and alpha-terthienyl on membrane permeability was investigated using liposomes entrapped with glucose as a model membrane system. Upon exposure to UV-A light, alpha-terthienyl, and to a much lesser extent phenylheptatriyne, induced leakage of glucose via a photodynamic mechanism in liposomes which had a high degree of unsaturated fatty acid side chains. Enhanced permeability to glucose in these liposomes due to the action of alpha-terthienyl and phenylheptatriyne involved lipid peroxidation, but neither of the two assays used to monitor lipid peroxidation (malondialdehyde and peroxide formation) was directly correlated with the increase in liposome permeability. In liposomes with highly ordered lipid where the fatty acid side chains are saturated, alpha-terthienyl had no effect on glucose permeability. In contrast, phenylheptatriyne was very effective in increasing glucose permeability in these liposomes via a photodynamic mechanism. Addition of lysophosphatidylcholine, which perturbs the order of lipid packing, to these liposomes, completely inhibited the effect of phenylheptatriyne. Conversely, incorporation of cholesterol which increases lipid order, into egg PC liposomes, enhanced the action of phenylheptatriyne. These data suggest that under UV-A irradiation (a) alpha-terthienyl and phenylheptatriyne enhance permeability in liposomes with a high degree of unsaturation involving lipid peroxidation and (b) phenylheptatriyne enhances membrane permeability through some other mechanism when present in a bilayer with a highly ordered lipid environment.     

Alpha activity: The influence of unpatterned light input and auditory feedback

The electroencephalographic alpha activity was studied in ten nonpaid healthy volunteers of either sex, 24-to-27 years of age, under the following experimental conditions: in the dark, in the presence of light of various intensity (1-foot candle, 3-foot candle, and 15-foot candle), with and without alpha contingent auditory feedback. Subjects wore light-diffusing goggles that prevented patterned vision throughout the experimental session.The diffuse-light input was found to be devoid of any effect on alpha activity in the absence of auditory feedback. However, during the feedback, the light intensity above 1-foot candle had a significant suppressant effect on alpha activity. This phenomenon can be explained by an interaction between these two modalities. The 40-minute feedback training did not enhance the basic capacity of subjects to produce alpha activity above their own baseline level.