Cytogenetic characterization of two partamona species (Hymenoptera, Apinae, Meliponini) by fluorochrome staining and localization of 18S rDNA Clusters by FISH

Abstract

The tribe Meliponini comprises several hundred species of stingless bees which are major pollinators of many tree species. In the present work we studied two Partamona species: Partamona helleri and Partamona seridoensis. Both species presented similar karyotypes with 2n = 34 chromosomes for females, pericentromeric heterochromatic blocks and terminal GC rich heterochromatic segments in chromosome pairs 2, 9, 10 and 15, as shown by sequential C banding-DA/CMA 3 staining. The heterochromatin is heterogeneous: pericentromeric and the terminal blocks behave quite differently. FISH with 18S rDNA probe showed that NORs were in terminal blocks. In addition, B chromosomes were observed in P. helleri. The results of the different treatments employed such as C banding and fluorochrome staining led us to believe that their origin was not due to non-disjunction of A genome chromosomes. Supernumerary pericentromeric heterochromatin and the non-homologous portion of a heteromorphic pair behaved in a similar fashion, indicating that may be originated by fission. The FISH assay showed, however that there was no sequence correspondence between these segments. © 2005 The Japan Mendel Society.