A Comparison of the Genetic Potential of Deoxyribonucleic Acids of Diverse Origin

During recent years much evidence has accumulated to suggest that deoxyribonucleic acid (DNA) is a carrier of the genetic specificity of cells. Studies of transforming principles obtained from pneumococcal and Hemophilus cells have provided a considerable part of this evidence. In 1944 Avery, MacLeod and McCarty showed that a DNA fraction isolated from Type III pneumococci was capable of transforming unencapsulated R variants derived from pneumococcus Type II into fully encapsulated Type III cells. These investigators suggested (1944) that the techniques used in such transformation studies offer a sensitive means of determining specific differences in the biological behavior of deoxyribonucleic acids. Subsequent work of the Rockefeller group and other investigators (for example, Zamenhof, Alexander and Leidy, 1953) has amply confirmed this view. The highly polymerized deoxyribonucleic acids that have been found to have transforming activity have all been extracted from intracellular locations. Recently, Catlin (1956) has reported the presence of a highly polymerized extracellular DNA in cultures of several species of bacteria. In view of the known tendency of bacterial populations to undergo rapid changes in genetic composition, a question of considerable interest concerns the possible genetic capacity of extracellular DNA. A study of this question has been undertaken, using transformation techniques comparable to those developed by Alexander and Leidy (1953) for inducing streptomycin resistance in a population of Hemophilus influenzae cells, which was initially sensitive to streptomycin. The genetic capacity of five preparations of DNA from bacteria has been investigated: intracellular DNA from H. influenzae: intracellular and extracellular DNA preparations from Micrococcus Lysodeikticus and from Pseudomonas fluorescens

THE EFFECTS OF FREEZING AND FREEZE-DRYING ON VIRUSES AND RICKETTSIAE

Interest in the cryotolerance of various biological entities ha.a been in evidence for many year•. Evaluation.a of changes due to variations in temperature have been made on a wide variety of biological structures. The majority of experimentations dealing with viruses and rickettsiae have been carried out with nonpurified preparations and have been only qualitative in nature. The purpose of the present study is to evaluate the cryotolerance of viruses and rickettsiae in purified and nonpurified preparations in a qualititative manner

History of Detroit and Wayne County and early Michigan:

Mode of access: Internet

The history of Detroit and Michigan;

xlvi, 1024 p. front., illus. (incl. maps, plans, facsims.) 26 cm

Wisconsin 1872

Includes text, data tables, illustrations and railroad information. "Entered according to act of Congress in the year 1872 by Silas Farmer, in the office of the Librarian of Congress, at Washington."Color1:1,140,000 1 in. = 18 mile

The history of Detroit and Michigan; or, The metropolis illustrated; a full record of territorial days in Michigan, and the annals of Wayne County.

Vol. 1 is a new ed. of the issue of 1882; v. 2, biographies.Mode of access: Internet

The history of Detroit and Michigan : or, the metropolis illustrated ; a chronological cyclopaedia of the past and present, including a full record of territorial days in Michigan, and the annals of Wayne county /

Includes index.Mode of access: Internet