Constitutive heterochromatin, NOR location and FISH in the grasshopper Xyleus angulatus (Romaleidae)

Summary C-banding, fluorochrome staining, silver staining and fluorescence in situ hybridization (FISH) were used to characterization of the meiotic chromosomes in the grasshopper Xyleus angulatus. The C-banding pattern showed perincentromeric heterochromatin blocks in all chromosomes, interstitial blocks in the L1, L2 and L3 pairs and distal blocks in medium and small-sized pairs. CMA3/DA staining revealed that these heterochromatic regions were characterized by high content of GC bases pairs. The ribosomal DNA probe (pTa71) showed strong hybridization signal in the pericentromeric regions at bivalents L3, M4 and X chromosome, corresponding to the silver-stained chromosomal positions of active NORs and the heterochromatic area CMA3 + of these chromosomes.