Physiologic and Transcriptomic Effects Triggered by Overexpression of Wild Type and Mutant DNA Topoisomerase I in .

Topoisomerase I (TopoI) in , encoded by , is a suitable target for drug development. Seconeolitsine (SCN) is a new antibiotic that specifically blocks this enzyme. We obtained the mutant, which encodes an enzyme less active than the wild type () and more resistant to SCN inhibition.

The balance between gyrase and topoisomerase I activities determines levels of supercoiling, nucleoid compaction, and viability in bacteria.

Two enzymes are responsible for maintaining supercoiling in the human pathogen , gyrase (GyrAGyrB) and topoisomerase I. To attain diverse levels of topoisomerase I (TopoI, encoded by ), two isogenic strains derived from wild-type strain R6 were constructed: P , carrying an ectopic copy under the control of the ZnSO-regulated P promoter and its derivative ΔP , which carries a deletion at its native chromosomal location. We estimated the number of TopoI and GyrA molecules per cell by using Western-blot and CFUs counting, and correlated these values with supercoiling levels.

Enamel Resistance to Demineralization After Bracket Debonding Using Fluoride Varnish.

The aim of this study was to evaluate the elemental content and morphology of enamel subjected to demineralization cycles after bracket debonding, adhesive remnant removal, and application of a fluoride varnish. 125 bovine teeth were divided into five groups (n = 25): 1) Intact enamel; 2) Intact enamel + demineralization cycles (DC); 3) Enamel after adhesive removal; 4)Enamel after adhesive removal + DC; 5) Enamel after adhesive removal + Profluorid + DC. The weight percentages of calcium (Ca), phosphorous (P) and fluoride (F) were calculated using energy dispersive X-ray spectroscopy (EDX).