No abstract

Daily cocaine administration has been shown to alter G proteins in mesolimbic nuclei, and these changes have been implicated in the initiation and expression of behavioral sensitization. To evaluate the robustness of changes in G proteins induced by daily cocaine treatments capable of producing behavioral sensitization, the levels of Gi1 alpha, Gi2 alpha, Go alpha, Gs alpha, and G beta protein were measured by immunoblotting at 1 hr after an acute injection of cocaine or saline given 1 or 14 days following the last injection of daily cocaine or saline. A significant decline in Gi1 alpha was seen in the nucleus accumbens at 14 days following daily cocaine administration regardless of whether they received an acute challenge with cocaine or saline 1 hr prior to decapitation. No alterations were observed in the ventral tegmental area, substantia nigra, dorsolateral striatum, or prefrontal cortex in the levels of Gi1 alpha, Gi2 alpha, or Go alpha. No change in G protein immunoreactivity was measured in the nucleus accumbens or ventral tegmental area of rats decapitated 1 hr after discontinuing daily cocaine. The possibility that a long-term change in Gi1 alpha in the nucleus accumbens may be related to cocaine-induced behavioral sensitization is discussed.

No abstract

RNA aptamers selected to bind fluorophores and activate their fluorescence offer a simple and modular way to visualize native RNAs in cells. Split aptamers which are inactive until the halves are brought within close proximity can become useful for visualizing the dynamic actions of RNA assemblies and their interactions in real time with low background noise and eliminated necessity for covalently attached dyes. Here, we design and test several sets of F30 Broccoli aptamer splits, that we call fluorets, to compare their relative fluorescence and physicochemical stabilities. We show that the splits can be simply assembled either through one-pot thermal annealing or co-transcriptionally, thus allowing for direct tracking of transcription reactions via the fluorescent response. We suggest a set of rules that enable for the construction of responsive biomaterials that readily change their fluorescent behavior when various stimuli such as the presence of divalent ions, exposure to various nucleases, or changes in temperature are applied. We also show that the strand displacement approach can be used to program the controllable fluorescent responses in isothermal conditions. Overall, this work lays a foundation for the future development of dynamic systems for molecular computing which can be used to monitor real-time processes in cells and construct biocompatible logic gates.

No abstract