CYTOGENETIC INVESTIGATIONS ON THE HOLOCENTRIC CHROMOSOMES OF TETRANEURELLA-AKINIRE (SASAKI) (HOMOPTERA, PEMPHIGIDAE)

The karyotype of the root aphid Tetraneurella akinire was analysed by means of C, G, and NOR banding. The overall base pair distribution was investigated after CMA, and DAPI fluorochrome staining. Both C and G treatments revealed a well defined banding pattern on the X and A1 chr omosomes. C-bands showed a marked polymorphism in both size and number , even within the same individual. NOR banding produced a precipitatio n of silver on one telomere of the X chromosome, which also showed bri ght fluorescence after CMA, staining. Treatment with DAPI uniformly st ained all chromosomes. Neither CMA3 nor DAPI showed bright fluorescenc e overlapping the C-positive bands. It can be concluded that T. akinir e chromosomes present a cluster of GC-rich DNA sequences located on on e telomere of the X chromosome, whereas the AT - sequences are regular ly arranged along the chromosome axes and not grouped into well define d clusters.