Heteropicnotic chromatin and nucleolar activity in meiosis and spermiogenesis of Limnogonus aduncus (Heteroptera, Gerridae): a stained nucleolar organizing region that can serve as a model for studying chromosome behavior

Abstract

ABStrACt. Males of Limnogonus aduncus were found to have the sex chromosome system X0 and chromosome number 2n = 23 (22A + X0). Testis cells were stained with lacto-acetic orcein and silver nitrate so that changes in the morphology and degree of staining of the heteropicnotic chromatin and the nucleolar material could be observed during meiosis and spermiogenesis. These structures share the same nuclear position and could be seen until almost the end of spermiogenesis. A chromosome region stained with silver ni-

Spermatogenesis of riffle bugs, Rhagovelia whitei and Rhagovelia sp (Veliidae), and backswimmers Martarega sp (Notonectidae)

“…In Rhagovelia sp, unlike what we observed in other insects (L. aduncus, Castanhole et al, 2008;E. meditabunda, Rebagliati et al, 2003), they had the NOR on the opposite side of the telomeric regions of the autosomes.…”

“…In Coreidae, a single NOR is present in the interstitial region of the largest autosome of Pachylis argentinus or in the telomeric region of an autosome in Carlisi wahlbergi (Fossey and Liebenberg, 1995) and Spartocera fusca (Cattani and Papeschi, 2004). In Pentatomidae and Gerridae, a single NOR was detected in the telomeric region of an autosome in Edessa meditabunda and L. aduncus, respectively (Rebagliati et al, 2003;Castanhole et al, 2008), in the middle position of the largest autosome in Nezara viridula or in the telomeric region of chromosome Y in Graphosoma italicum (González-García et al, 1996).…”

“…All of the species described have shown a single NOR located in the middle or subterminal position of an autosome or of a sex chromosome (González-García et al, 1996;Papeschi and Bressa, 2002;Papeschi et al, 2003;Cattani and Papeschi, 2004;Castanhole et al, 2008). Recently, Bressa et al (2009) reported two NORs in the X chromosome of Dysdercus albofasciatus, resulting from a gonosome-autosome fusion, one of the NORs originating from the ancestral X chromosome and the other from the autosome.…”

Cytogenetic evidence for de novo synthesis of rRNA and involvement of nucleolar material in the organization of cell structures during spermiogenesis of Chariesterus armatus (Heteroptera, Coreidae

“…Proteins necessary for rRNA transcription and pre-ribosome processing are able to reduce silver nitrate, acquiring a dark brown color. Thanks to these techniques, the knowledge about nucleolar activity and its regulation has advanced greatly in a relatively short time (Bicudo, 1982;Capoa et al, 1985;Shaw and Jordan, 1995;Santoro et al, 2002;de Oliveira and de Campos Bicudo, 2006;Severi-Aguiar et al, 2006;Das and Khuda-Bukhsh, 2007;Castanhole et al, 2008). In the present study, the protocol of Howell and Black (1980) was used, yielding information on morphological changes and interactions of the nucleolar material during the spermiogenesis of the heteropteran C. armatus.…”

Description of the pre-reductional sex chromosome during male meiosis of Pachylis laticornis (Heteroptera: Coreidae)

“…laticornis showed pre-reduction division for the X chromosome and the autosomes. This type of division, although common for organisms with monocentric chromosomes (Ueshima, 1979), is relatively uncommon for heteropterans, which usually present the first meiotic division as equational for the sex chromosomes (Ueshima, 1979), as showed by Ueshima (1979), Papeschi et al (2003), Bressa et al (2005), Souza (2009), Souza et al (2007a,b, 2011), and Castanhole et al(20082010;2012). However, pre-reduction division was also reported for species of the genus Pachylis (P. aff pharaonis, P. argentinus, P. lateralis), Archimerus (A. alternatus e A. calcarator) (Coreidae), the genus Anisops (A. fieberi, A. niveae, and A. sardea) (Notonectidae), Ectrychote dispar (Reduviidae), as well as for all species of the family Tingidae, prior to cytogenetic study (Ueshima, 1979;Papeschi et al, 2003, Ramos, 2009.…”