RESUMO
Plasmid Rsc13, a small derivative of the plasmid R1, contains a region necessary for replication as well as a complete copy (4957 bp) of the ampicillin resistance transposon, Tn3. We determined the nucleotide sequence of the replication region of Rsc13 to be 2937 bp and then compared this region (designated the 2.9-kb region) to the analogous region of pSM1, a small derivative of the plasmid R100 which has common ancestry with R1. Rsc13 and pSM1 were 96% homologous in this 2.9-kb region except for a discrete region of about 250 bp which showed only 44% homology. The sequence and distribution of nucleotide substitutions between Rsc13 and pSM1 supported a map of possible genes and sites which have previously been seen in the replication region of Rsc13 and pSM1 which showed only 44% homology. Analysis of the amino acid sequence and predicted conformation of the two RepA2 polypeptides, however, suggested that they were very similar. We proposed that the repA2 region of R1 and R100 was replaced by a substitution of a short DNA segment from another plasmid which was evolutionarily related to R1 and R100 but had more divergence. This event may have been mediated by a mechanism similar to that of gene conversion as described in eukaryotic systems.
Assuntos
DNA Bacteriano/análise , Escherichia coli/genética , Fatores R , Ampicilina/farmacologia , Sequência de Bases , Evolução Biológica , Computadores , Elementos de DNA TransponíveisAssuntos
Anestesia Dentária/métodos , Assistência Odontológica para a Pessoa com Deficiência/métodos , Hipertermia Maligna/fisiopatologia , Adolescente , Criança , Dantroleno/administração & dosagem , Feminino , Humanos , Masculino , Medicação Pré-Anestésica , Risco , Tiamilal/administração & dosagemRESUMO
We have demonstrated analytically and numerically that at least 10-100-fold enhancements in intensities for similar input energies can be achieved in the focal region of a thin dielectric lens by the use of pulsed beams specifically designed for that purpose.