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.     

NUCLEAR DNA CONTENT IN POPULATIONS OF PINUS RIGIDA

Five populations of Pinus rigida growing in contrasting ecological situations ranging from North Carolina (35°53'N latitude) to Quebec (45°06'N latitude) showed no significant variation in amounts of nuclear DNA with respect to germinating seedlings. Nuclear volume of dormant nuclei also showed no significant variation between and within populations, a finding that is consistent with the concept that the basic 2C DNA value of Pinus rigida is uniform under all habitats. This finding is in contrast to numerous reports for other coniferous species.     

Electrophoretic detection of the internal parasite, Aphidius matricariae in Myzus persicae

The presence of the internal parasite (Aphidius matricariae) of the aphid Myzus persicae can be identified by electrophoresis, and staining of several enzyme systems, of which malate dehydrogenase is recommended as the most reliable. It is suggested that the technique could be extended to other small insects, and that pest populations can be screened for percentage parasitism as an adjunct to insecticide and integrated control field trials.