Bacterial transposons and the mechanisms of their transposition

The published data on molecular mechanisms of transposons movement inside and between genomes are reviewed. The replicative mechanism of transposition of the family of Tn3-like elements is discussed, as well as the modes of bacteriophage Mu, Tn9, Tn10, Tn903 transposition. The factors affecting the choice of transposition pathways are analysed.     

Morphogenesis and Homology in Arthropod Limbs

Arthropods exhibit highly diverse limb morphologies rangingfrom unbranched walking legs to multibranched swimming paddles.Understanding morphogenesis in structurally diverse limbs canbe useful for ascertaining homologies between limbs. Structurallysimilar limbs have been produced by different evolutionary modificationsof morphogenesis in certain cases. Whereas it is easy to supportthe claim that whole arthropod limbs are homologous structures,I demonstrate that it is not always possible to draw well-foundedhomologies between parts of different limbs. This result isimportant with regard to general models of appendage developmentand evolution in arthropods because it clarifies contradictoryexplanations based exclusively on gene expression data.     

Transduction and Genetic Homology Between Pseudomonas Species putida and aeruginosa

Genetic crosses occur by transduction between the species Pseudomonas aeruginosa and P. putida. The frequency relative to intraspecific transfer is reduced and varies among markers, suggesting that these genomes contain discrete regions of homology and nonhomology.