To date no nucleic acid has been found in the purified infectious agent which causes the spongiform encephalopathy known as scrapie. In an attempt to identify a unique scrapie virus-associated messenger RNA in tissues of infected animals, we have synthesized an oligonucleotide probe complementary to the mRNA sequence corresponding to the amino-acid sequence of the prion protein, PrP27-30 (ref. 1). We report here that, with this probe, a complementary DNA clone representing PrP27-30 was obtained from scrapie-infected mouse brain; the DNA sequence of this clone could be translated into a protein that matches exactly the published sequence of PrP27-30. The cDNA clone hybridized to a single 2.4-2.5-kilobase (kb) mRNA from both normal and scrapie-infected brain. Thus, the PrP27-30 mRNA is not uniquely associated with scrapie infectivity, suggesting that PrP27-30 may be a normal component of mouse and hamster brain.

Amino Acid Sequence↗

PubMedDate not supplied

Time and distance scales of membrane domain organization.

Time and distance scales in membranes are discussed in relation to the inference of domain structure from spectroscopic measurements. Each type of spectroscopy has a natural time scale set by the magnitude of the interactions that determine the spectral width. For fluid membranes, the lateral diffusion of the lipid molecules then implies an associated distance scale over which the measurements are averaged. These factors have an influence on the interpretation of spectroscopic measurements and on whether or not the spectroscopic technique is capable of distinguishing neighbouring domains from each other. NMR occupies a special place among spectroscopies because its time scale is so long. Some examples are given of the conceptual role of spectroscopic time and distance scales with regard to the inference of domains in membranes from NMR or other spectroscopic studies, or the apparent failure to detect domains believed to be present. These examples include mixtures of phospholipids with cholesterol and/or protein molecules. In addition to time scales being set by line width and line shape considerations, the study of relaxation times within a given spectroscopy carries its own characteristic insights into motional correlation times.

Electron Spin Resonance Spectroscopy↗

PubMedDate not supplied

The prevention and treatment of child abuse in households of substance abusers: a research demonstration progress report.

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Adolescent↗