Cytogenetic characterization of the genome of mealybug Planococcus citri (Homoptera, Coccoidea)

Summary Mealybugs although being agriculturally harmful insects have been very poorly studied by modern cytogenetics techniques, and no cytotaxonomic criteria to distinguish between closely related species is available yet. In the mealybug Planococcus citri (2n=10) male and female individuals are both diploid, however in males, at the stage of blastula, the haploid chromosome set of paternal origin becomes heterochromatic, even though its complete inertia has been considered questionable. Here we present data on the cytogenetic characterization of the chromosomes of Planococcus citri. We report on (i) the fluorescence karyotype (D287/170), which to our knowledge is the first banded karyotype of a mealybug to be described; (ii) the chromosome localization of constitutive heterochromatin; (iii) the chromosome localization of rDNA sites; (iv) NORs activity. Our data also show, for the first time, that in the heterochromatic chromosome set ribosomal genes are still active

The Italian National Project of Astrobiology-Life in Space-Origin, Presence, Persistence of Life in Space, from Molecules to Extremophiles

The \u2018\u2018Life in Space\u2019\u2019 project was funded in the wake of the Italian Space Agency\u2019s proposal for the development of a network of institutions and laboratories conceived to implement Italian participation in space astrobiology experiments

Simultaneous production of Q and R bands after staining with chromomycin A3 or olivomycin.

Human and mouse chromosomes, stained with either chromomycin A3 or olivomycin, which bind preferentially to G - C-rich DNA (where G is guanosine and C is cytosine), exhibit a Q or a reverse banding pattern, depending on the wavelength used for excitation. The two complementary banding patterns can be observed in the same metaphase simply by changing the combination of excitation filters. These data suggest, therefore, that in addition to base composition, other factors are involved in the production of chromosome banding by chromomycin A3 and olivomycin