Sequential FISH Analysis with rDNA Genes and Ag-NOR Banding in the Lady Beetle Olla v-nigrum (Coleoptera: Coccinellidae)

Abstract

We have characterized the meiosis of Olla v-nigrum by standard analysis, performed a NOR study using NOR banding, FISH of rDNA genes and sequential FISH/AgNOR analysis, and adapted the FISH methodology to Coccinellidae. The chromosome number determined at metaphase I was n = 9 + Xyp. At zygotene it was possible to identify the sex vesicle which presented a deeply stained heteropycnotic block. Chromosome X is much larger than the y and the two combine, forming a "parachute" in metaphase I. FISH analysis using a probe of rDNA genes 18S, 28S and 5.8S of D. melanogaster was used to map the genes in the sex vesicle. The NOR band showed high gene activity in this region. These results were confirmed using sequential FISH/Ag NOR analysis. The data obtained for Olla v-nigrum agree with the classical hypothesis raised to explain the type of sex chromosome association in a parachute format (Xyp) as being due to the presence of nucleolar material. The chromosome number and parachute configuration during metaphase I in this species agree with the basic karyotype of most Coleopterans. The major adaptation of the FISH method was the simultaneous denaturation and hybridization that permitted preservation of chromosome morphology, an essential factor when the chromosomes are small.

Cytogenetic data of Partamona peckolti (Hymenoptera, Apidae, Meliponini) by C banding and fluorochrome staining with DA/CMA3 and DA/DAPI

“…Another small DA/CMA 3 + band seen with or without the C banding treatment which presented the shape and richness in GC base pairs led us to believe that we were evidencing a nucleolar organizer region (NOR) (Figure 3 arrowhead). This correlation between CMA 3 + bands and NORs is quite common among animals and in insects has been observed in: the grasshoppers Eyprepocnemis plorans and Locusta migratoria (Camacho, et al, 1991); the wasp Trypoxylon albitarse (Araújo et al, 2000;2002); the lady beetle Olla v-nigrum (Maffei et al, 2001a); and in other Meliponini bees such as Melipona (Rocha and Pompolo, 1998;Rocha et al, 2002); Plebeia (Caixeiro, 1999) and Friesella 54 Brito et al schrottkyi (Mampumbu, 2002). The location of these regions by the classical technique of Howell and Black (1980) is difficult on Meliponinae chromosomes that was effectively achieved only in Tetragonisca angustula (Menezes, 1997), Melipona (Maffei et al, 2001b;Rocha et al, 2002); Plebeia (Maffei et al, 2001b) and Friesella schrottkyi (Mampumbu, 2002).…”

Cytogenetic Characterization of Two Partamona Species (Hymenoptera, Apinae, Meliponini) by Fluorochrome Staining and Localization of 18S rDNA Clusters by FISH

“…The FISH results with rDNA 18S probe confirmed that pairs number 2, 9, 10 and 15 carry cistrons for the ribosomal RNA. The same correspondence of CMA 3 ϩ /NOR has been observed in the coleopteran Olla v-nigrum (Maffei et al 2001a); and in the wasp Trypoxylon albitarse (Araújo et al 2000); the stingless bees Plebeia and Melipona (Maffei et al 2001b); Friesella schrottkyi (Mampumbu 2002) and Partamona peckolti (Brito et al 2003).…”

Karyotypic description of four species of Trigona (Jurine, 1807) (Hymenoptera, Apidae, Meliponini) from the State of Mato Grosso, Brazil

“…In T. chanchamayoensis, a marked reaction was seen with DA/CMA 3 ( Figure 4A), while in T. recursa, the staining with CMA 3 revealed no GC-rich regions in the chromosomes ( Figure 4B). The positive reactions seen were probably associated with nucleolus organizing regions (NORs), as observed in 188 Costa et al other insects such as Orthoptera (Camacho et al, 1991), Coleoptera (Maffei et al, 2001), and in other Hymenoptera, including Formicidae (Palomeque et al, 1988;Imai et al, 1992), Sphecidae (Araújo et al, 2000) and Meliponini (Brito et al, 1999(Brito et al, , 2003Caixeiro, 1999;Rocha, 2000). Some authors have suggested that the number of NORs revealed by impregnation with silver nitrate or by CMA 3 staining is an important taxonomic character.…”