Base composition of duck 10S RNA and its poly(A) segment

The base composition of the poly(A) segment of duck 10S RNA was determined to be 92% AMP and 8% GMP. The GMP was probably the result of contamination of poly(A) with other segments of the RNA. A comparison of the theoretical and determined base compositions of the whole 10S RNA molecule suggested that it contains, besides a coding sequence, two noncoding sequences only one of which is poly(A).Abbreviations AMP adenylic acid - GMP guanylic acid - CMP cytidylic acid - UMP uridylic acid - SDS sodium dodecyl sulfate - EDTA ethylene diamine tetraacetic acid - TCA trichloroacetic acid     

Bacterial growth and the concentrations of cyclic nucleotides inLegionella pneumophila cultures

The growth kinetics ofLegionella pneumophila, and the rates of DNA and RNA synthesis in this organism, are qualitatively similar to that of other gram negative organisms of clinical importance. After a brief stationary phase, culture viability is rapidly lost. This loss of viability is not associated with detectable cell lysis or with significant breakdown of cellular DNA; it is, however, preceded by the rapid breakdown of approximately 50% of the cumulatively labeled RNA. During logarithmic growth in buffered yeast extract broth, bacterial cells secreted into the medium large amounts of cyclic GMP at both 37°C and room temperature, while those grown in a buffered synthetic broth did not. Cyclic AMP increased moderately during stationary phase at 37°C and room temperature in both media. Neither added cyclic AMP nor added cyclic GMP influenced the rate of growth ofL. pneumophila in either broth, with or without 1-methyl-3-isobutyl-xanthine, a phosphodiestease inhibitor. Dibutyrul cyclic AMP and 8-bromo cyclic GMP individually or in combination also had no effect on growth.     

Temperature-controlled properties of DNA complexes with poly(ethylenimine)-graft-poly(N-isopropylacrylamide)

End-functionalized poly(N-isopropylacrylamide) (PNIPA) was synthesized by living free radical polymerization and conventional free radical polymerization and was used to prepare graft copolymers with poly(ethylenimine) (PEI). The copolymers exhibited lower critical solution temperature (LCST) behavior between 30 and 32 degrees C and formed complexes with plasmid DNA. The LCST of the copolymers in the DNA complexes increased slightly to approximately 34-35 degrees C. Cytotoxicity of the copolymers was evaluated by measuring lactate dehydrogenase (LDH) release from cells. The copolymers exhibited temperature-dependent toxicity, with higher levels of LDH release observed at temperatures above the LCST. Cellular uptake and transfection activity of the DNA complexes with the PEI-g-PNIPA copolymers were lower than those of the control PEI/DNA complexes at temperature below the LCST but increased to the PEI/DNA levels at temperatures above the LCST.