Molecular characterization of constitutive heterochromatin in three species of Trypoxylon (Hymenoptera, Crabronidae, Trypoxylini) by CMA3/DAPI staining

Abstract

Previous cytogenetic analyses in Trypoxylon Latreille, 1796 have been basically restricted to C-banding. In the present study, base-specific CMA3 and DAPI fluorochrome staining were used to characterize the constitutive heterochromatin in three Trypoxylon species. The heterochromatin was GC-rich in all the species studied; however, in Trypoxylon nitidum F. Smith, 1856the molecular composition of the heterochromatinwasdifferent among chromosome pairs. Conversely, the euchromatin was AT-rich in the three species. These results suggest high conservatism in the euchromatic regions as opposed to the heterochromatic regions that have a high rate of changes. In this study, we report the karyotype of Trypoxylon rugifrons F. Smith, 1873which has the lowest chromosome number in the genus and other characteristics of the likely ancestral Trypoxylon karyotype.

A cytogenetic study of three parasitic wasp species (Hymenoptera, Chalcidoidea, Eulophidae, Trichogrammatidae) from Brazil using chromosome morphometrics and base-specific fluorochrome staining

“…As for both CMA 3 - and DAPI-positive chromosome arms found in Palmistichus elaeisis , segments of that kind detected in other Hymenoptera are usually heterochromatic (see e.g. Menezes et al 2011). Interestingly, fully heterochromatic chromosome arms in parasitic wasps were also revealed, for example, on a particular pair of metacentric chromosomes of three species of the genus Nasonia Ashmead, 1904 (Gokhman and Westendorff 2000).…”

“…two Entedon Dalman, 1820 (Entedoninae) and several Pnigalio Schrank, 1802 (Eulophinae) species (Bernardo et al 2008, Bolsheva et al 2012, Gebiola et al 2012). On the other hand, occurrence of multiple telomeric CMA 3 -positive bands found in the karyotype of Trichospilus diatraeae is apparently derived and quite unusual for parasitoids, but is known for aculeate wasps (Menezes et al 2011) and bees (Duarte et al 2009). In the latter study, most CMA 3 -positive bands are attributed to NORs, and this is probably true for Trichospilus diatraeae as well.…”

The roles of barriers, refugia, and chromosomal clines underlying diversification in Atlantic Forest social wasps

“…It is not surprising that heterochromatic regions composed of repetitive DNA are hotspots for chromosomal rearrangements 89 – 91 . Although we did not perform cytogenetic tests to detect heterochromatic regions and/or specific families of repetitive DNA, it is possible that GC-rich sites in Synoeca represent these types of genomic regions, as verified in other insects including beetles 92 and hymenopterans including solitary 93 and social 91 wasps.…”