Cytogenetic Analysis of Epicauta Atomavia (Meloidae) and Palembus Dermestoides (Tenebrionidae) with Xyp Sex Determination System Using Standard Staining, C-Bands, NOR and Synaptonemal Complex Microspreading Techniques

Abstract

The mitotic and meiotic chromosomes of the beetles Epicautu atomaria (Meloidae) and Palembus dermestoides (Tenebrionidae) were analysed using standard staining, C-banding and silver impregnation techniques. We determine the diploid and haploid chromosome numbers, the sex determination system and describe the chromosomal morphology, the C-banding pattern and the chromosome(s) bearing NORs (nucleolar organizer regions). Both species shown 2n = 20 chromosomes, the chromosomal meioformula 9 + Xy,, and regular chromosome segregation during anaphases I and 11.The chromosomes of E. utomariu are basically metacentric or submetacentric and P. dermestoides chromosomes are submetacentric or subtelocentric. In both beetles the constitutive heterochromatin is located in the pericentromeric region in all autosomes and in the X, chromosome; additional C-bands were observed in telomeric region of the short arm in some autosomes in P. dermestoides. The yp chromosome did not show typical C-bands in these species. As for the synaptonemal complex, the nucleolar material is associated to the 7th bivalent in E. aromaria and 3rd and 7th bivalents in P. dermestoides. Strong silver impregnated material was observed in association with Xy, in light and electron microscopy preparations in these species and this material was interpreted to be related to nucleolar material.

Comparative cytogenetic analysis in 13 tortoise beetles (Coleoptera: Chrysomelidae: Cassidinae) from Brazil

“…This same pattern was also observed in the autosomal chromosomes of Coleoptera (Virkki, 1983, Schneider et al, 2006Mello et al, 2014). In the sex chromosomes, the heterochromatin can extend to all chromosome arms or is restricted exclusively in the pericentromeric region (Almeida et al, 2000;Rozek et al, 2004).…”

A study of the constitutive heterochromatin and nucleolus organizer regions of Isocopris inhiata and Diabroctis mimas (Coleoptera: Scarabaeidae, Scarabaeinae) using C-banding, AgNO3 staining and FISH techniques

“…According to previous reports, in addition to pericentromeric C-bands, distal C-bands were also observed in the tenebrionids Misolampus goudoti (Juan and Petitpierre, 1989) and Palembus dermestoides (Almeida et al, 2000), while exclusively telomeric blocks were observed in the carabid Bembidion minimum (Rozek and Rudek, 1992). The additional C-bands in these beetles and in D. mimas and I. inhiata probably arose by small tandem duplications, as proposed by King and John (1980).…”

Cytogenetics of the darkling beetles Zophobas aff. confusus and Nyctobates gigas (Coleoptera, Tenebrionidae)

“…In addition, as observed in Z. aff. confusus, the presence of euchromatic y has been described in Gymnopleurus sturmi (Scarabaeidae), Palembus dermestoides (Tenebrionidae), Epicauta atomaria (Meloidae), and in 23 of the 25 studied species of Pimelia (Tenebrionidae) (Almeida et al, 2000;Colomba et al, 2000;Pons, 2004). In these species, the lack of labeling can be due to the minuscule size of the CH blocks in the yp.…”

“…The chromosomal morphology is generally metacentric and submetacentric, with chromosomes having similar sizes, which renders the identification of individual species difficult (Petitpierre, 1996). Some studies have focused on the distribution and base pair composition of the constitutive heterochromatin in the karyotypes of Tenebrionidae species (Juan and Petitpierre, 1989;Almeida et al, 2000;Pons, 2004). In general, the heterochromatin has a pericentromeric location and accounts for about 50% of the genome and constitutes monomeric sequences with varying sizes of 100-360 base pairs (Mestrovic et al, 2000).…”