First Record of a B Chromosome in <b><i>Polybia fastidiosuscula</i></b> Saussure (Vespidae) and Investigation of Chromatin Composition Through Microsatellite Mapping

Abstract

The characterization of karyotypes is an important aspect in understanding the structure and evolution of genomes. Polybia is a genus of social wasps of the family Vespidae. This genus has 58 species, but for only 8 of these chromosome number and morphology have been reported in the literature. The aim of this study was to describe and characterize the Polybia fastidiosuscula Saussure karyotype, presenting the first case of a B chromosome in Vespidae. In addition, we investigated the chromatin composition of this species through C-banding, base-specific fluorochrome staining, and physical mapping of 7 microsatellites and 18S rDNA. Four colonies of P. fastidiosuscula from Minas Gerais and Paraná states, Brazil, were analyzed. The chromosome number identified was 2n = 34, and 2 colonies presented a B chromosome. We characterized the chromatin composition of this species, analyzing the existence of different microsatellite-rich heterochromatic regions which are also enriched with AT or GC base pairs. We suggest an intraspecific origin of the B chromosome based on the homology of the heterochromatic composition with A chromosomes and also verify that the TTAGG and TCAGG sequences are not telomeric, but only microsatellites that occur in the centromeres of most chromosomes, as well as GAG and CGG.

Cytogenetic Analysis of the Fungus-Farming Ant Cyphomyrmex rimosus (Spinola, 1851) (Formicidae: Myrmicinae: Attini) Highlights Karyotypic Variation

“…The distribution pattern of microsatellite (GA) 15 observed on the chromosomes of C. rimosus was restricted to the euchromatic region, corresponding to most of the chromosomal length, a pattern similar to that reported for C. transversus (2n = 18), other fungus-farming ants [Micolino et al, 2019b;Teixeira et al, 2022], and other hymenopterans [Travenzoli et al, 2019;Marchioro et al, 2020]. In contrast to C. rimosus, which showed a scattered distribution pattern for microsatellite (GA) 15 , additional specific bands have been observed in other fungus-farming ants, such as Mycetomoellerius holmgreni (Wheeler, 1925) [Micolino et al, 2019b], Sericomyrmex sp., and Mycocepurus goeldii (Forel, 1893); these bands may be related to mobile elements or gene regions [Teixeira et al, 2022].…”

Karyotype conservation and genomic organization of repetitive sequences in the leaf-cutting ant Atta cephalotes (Linnaeus, 1758) (Formicidae: Myrmicinae)

“…tif, the canonical telomeric sequence in vertebrates, have been previously observed in some chromosomes of bulldog ants through FISH (Meyne et al 1995) and even in the fire ant Solenopsis invicta Buren, 1972 (Myrmicinae) through sequencing analysis (Wurm et al 2011). The (TCAGG) n motif has been detected in telomeres of some clades of the order Coleoptera (reviewed by Kuznetsova et al 2020) and has recently been characterized as a microsatellite located in the centromeric heterochromatin of the social wasp P. fastidiosuscula (Marchioro et al 2020). Our physical mapping data showed that such telomeric sequence variations are absent in any portion of the A. cephalotes chromosomes.…”

“…In the present study, the heterochromatin of A. cephalotes had no trace of several microsatellites, such as (GA) 15 , (CA) 15 , (TAT) 10 , (CGG) 10 , (GAG) 10 , (CAA) 10 , and (TCAGG) 6 . However, these microsatellites are present in the heterochromatic regions of other Hymenoptera species, like the bees' Frieseomelitta species and M. seminigra merrilae, and the wasp P. fastidiosuscula (Santos et al 2018;Marchioro et al 2020;Barbosa et al 2021). Either these microsatellites were located in euchromatin, or there were no signals produced on the A. cephalotes chromosomes.…”

“…In addition to ribosomal DNA, other repetitive sequences, such as microsatellites, make up the genome of eukaryotes; they comprise short repeats of 1-6 bp, also denominated simple sequence repeats (SSRs), which are common and widely distributed in the genomes of organisms (reviewed by Martins et al 2011;López-Flores and Garrido-Ramos 2012). SSRs have been widely used as landmarks in different organisms, including insects, appearing as a nonrandom distribution on the chromosomes (Cuadrado et al 2008;Ruiz-Ruano et al 2015;Travenzoli et al 2019aTravenzoli et al , 2019bMarchioro et al 2020). In some grasshoppers' karyotypes, microsatellites have shown scattered or clustered distribution only in euchromatin (Ruiz-Ruano et al 2015).…”

“…Contrastingly, Frieseomelitta Ihering, 1912 species stingless bees show a prevalence of marks coincident with heterochromatic regions, in addition to euchromatic regions in some species (Santos et al 2018). In the wasp Polybia fastidiosuscula Saussure, 1854, most SSRs are located predominantly in heterochromatic regions, and only (GA) 15 was observed in euchromatin (Marchioro et al 2020).…”