The VSP enables students to practice their history-taking skills before encounters with standardized or actual patients. Future developments will focus on creating an assessment module that will automatically analyze VSP sessions and provide immediate student feedback.

No abstract

The deoxyribonucleic acid (DNA) of Bacillus subtilis phage PBS2 has been confirme,d to contain uracil instead of thymine. PBS2 phage infection of wild-type cells or DNA polymerase-deficient cells results in an increase in the specific activity of DNA polymerase. This induction of DNA polymerase activity is prevented by actinomycin D and chloramphenicol. In contrast to the major B. subtilis DNA polymerase, which prefers deoxythymidine triphosphate (dTTP) to deoxyuridine triphosphate (dUTP), the DNA polymerase in crude extracts of PBS2-infected cells is equally active whether dTT? or dUTP is employed. This phage-induced polymerase may be responsible for the synthesis of uracil-containing DNA during PBS2 phage infection.on July 6, 2020 by guest

The induction of viral enzymes, the synthesis of DNA, and the production of progeny phase during infection of Bacillus subtilis'by bacteriophage PBS2 are all unaffected by the presence of rifampicin. Rifampicin, rifamycin SV, streptovaricin, Copyright @ I9 72 by Academic Press. Inc. 1578 AN rights of reproduction in any form reserved.

Degradation of uracil-containing DNA by Bacillus subtilis extracts and its inhibition after infection by the uracil-containing DNA phage PBS2 have been investigated to resolve differences between the published reports of Tomita and Takahashi (1975) and Friedberg et al. (1975, 1976). The product of hydrolysis of PBS2 DNA, tritium labeled in its uracil and cytosine residues, is solely uracil and not deoxyuridine. The degrading activity is completely inhibited within 7 min after PBS2 infection, before any other known PBS2-induced protein is detectable. The production of the PBS2 inhibitor (a small, heat-stable protein) continues until 10 to 20 min postinfection.