CLOSELY-RELATED DROSOPHILA-MELANOGASTER STRAINS WITH ALTERED FITNESS ALSO SHOW CHANGES IN THEIR HOBO ELEMENT PROPERTIES

A set of Drosophila melanogaster strains of common origin, but with di fferent fitness characteristics, established either spontaneously or a fter selection for the specific fitness parameters, appear to induce n on-P-element-mediated gonadal atrophy in appropriate crosses to tester strains containing or lacking hobo elements (H and E strains). Using the gonadal dystrophy (GD) sterility assay, as well as genomic Souther n blot hybridization and in situ hybridization on polytene chromosomes , it was found that all these strains possess hobo elements whose dysg enic activity, composition, copy number and cytogenetic locations appe ared to be variable. In general, low fitness strains have moderate hob o-activity and hobo-repression potentials, while high fitness strains show no hobo-activity but also quite high hobo-repression potentials. Although distinct differences in the composition, copy number and loca tion of the hobo elements in the genome were observed between these 2 groups of strains, these variations did not show any profound correlat ion with either hobo-related dysgenic potential or the fitness of the strains.