Open AccessGenomic Changes in Nucleotide and Dinucleotide Frequencies in Pasteurella multocida Cultured Under High Temperature
Author(s) -
Xuhua Xia,
Ting Wei,
Zhoujie Xie,
Antoine Danchin
Publication year - 2002
Publication title -
genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.792
H-Index - 246
eISSN - 1943-2631
pISSN - 0016-6731
DOI - 10.1093/genetics/161.4.1385
Subject(s) - virulence , biology , pasteurella multocida , strain (injury) , rapd , gc content , genome , genetics , gene , bacteria , population , genetic diversity , demography , anatomy , sociology
We used 94 RAPD primers of different nucleotide composition to probe the genomic differences between a highly virulent P. multocida strain and an attenuated vaccine strain derived from the virulent strain after culturing the latter under increasing temperature for approximately 14,400 generations. The GC content of the vaccine strain is significantly (P < 0.05) lower than that of the virulent strain, contrary to the popular hypothesis of covariation between the GC content and temperature. The frequencies of AA, TA, and TT dinucleotides were higher, and those of AT, GC, and CG dinucleotides were lower, in the vaccine strain than in the virulent strain. A statistic called genomic RAPD entropy is formulated to measure the randomness of the genome, and the genome of the vaccine strain is more random than that of the virulent strain. These differences between the virulent and vaccine strains are interpreted in terms of mutation and selection under increased culturing temperature. A method for estimating substitution rates is developed in the appendix.