Two fluorine-containing analogues of the cyclic AMP receptor protein (CRP) from Escherichia coli were prepared by biosynthetic incorporation of 5-fluorotryptophan (5-F-Trp) and 3-fluorotyrosine (3-F-Tyr). The 19F-n.m.r. spectrum of the [5-F-Trp]CRP showed two signals corresponding to the two tryptophan residues, and that of the [3-F-Tyr]CRP showed six signals (two overlapping) corresponding to ...

The intracellular ratio of adenosine 3',5'-cyclic monophosphate (cyclic AMP) to guanosine 3',5'-cyclic monophosphate (cyclic GMP) may control the developmental pathway followed by antibody-forming cell (AFC) precursors. The evidence for this is derived from several different types of experiments. First lipopolysaccharide (LPS) which is mitogenic for B lymphocytes, stimulates rapid, transient ch...

Causes of cyclic fluctuations in abundance (population cycles) of some small-mammal populations remain poorly understood despite 6 decades of research and .20 hypotheses. Population cycles are demographic processes and cannot be fully explained without considering demographic mechanisms that underlie cyclic fluctuations in abundance. From simulation studies, we have recently shown that phase-re...

Many spatio-temporal phenomena (both natural and human) change in time cycles, e.g., seasonal change of weather and pattern of people’s daily activities, which required a cyclic view of time. However, most GIS systems and cartographic representation adopt Cartesian Coordinate Systems (CCSs), which force time to be perceived as a linear dimension. Therefore, the cyclic change cannot be effective...

Amoebae of Dictyostelium discoideum respond to a chemotactic cyclic AMP stimulus within 10 s by the formation of an intracellular peak of cyclic GMP. In wild-type cells the cyclic GMP is rapidly degraded by a cyclic GMP-specific phosphodiesterase. In "streamer F" mutants this enzyme structural gene, and the cyclic GMP persists several times longer than the normal period, an effect that is corre...

Background: Phosphodiesterase 3A (PDE3A) and phosphodiesterase 3B (PDE3B) play a critical role in the regulation of intracellular level of adenosine 3´,5´-cyclic monophosphate (cyclic AMP, cAMP) and guanosine 3´,5´-cyclic monophosphate (cyclic GMP, cGMP). Subsequently PDE3 inhibitors have shown to relax vascular and inhibit platelet aggregation in cardiovascular disease. Objectives: In th...