Chromosome study in Schistocerca (Orthoptera-Acrididae-Cyrtacanthacridinae): karyotypes and distribution patterns of constitutive heterochromatin and nucleolus organizer regions (NORs)

Abstract

Chromosome analyses were performed in two grasshopper species of the genus Schistocerca, S. pallens and S. flavofasciata. Both species shared the same diploid number (2n = 23, X in males; 2n = 24, XX in females);and a conserved karyotype composed exclusively of acrocentric chromosomes, but differed in their distribution patterns of constitutive heterochromatin and nucleolus organizer regions (NORs). Constitutive heterochromatin was located in the pericentromeric region of all chromosomes in both species. S. flavofasciata presented an additional C-band on the distal region of the long arm of a small autosome pair (S9). Nucleolus organizer regions (NORs), revealed by silver nitrate staining (Ag-NORs), were observed on a medium autosome pair (M5) in both species. S. pallens presented an additional NOR-bearing autosome (M6). The same sites were labeled after FISH with an rDNA probe in S. pallens cells.

Ommexecha virens (Thunberg, 1824) and Descampsacris serrulatum (Serville, 1831) (Orthoptera, Ommexechidae): karyotypes, constitutive heterochromatin and nucleolar organizing regions

“…The pericentromeric pattern of distribution of constitutive heterochromatin observed in Descampsacris serrulatum and Ommexecha virens is quite common for the superfamíly Acridoidea . This pattern has also been described for several species of the Neotropical Region, belonging the families Acrididae and Romaleidae ( Souza and Kido 1995 , Rocha et al 1997 , Loreto and Souza 2000 , Rocha et al 2004 , Loreto et al 2005 , Souza and Melo 2007 ). In Ommexechidae the only species, Spathalium helios , was studied with chromosomal C-banding technique until now.…”

“…Differential cytogenetic staining in grasshoppers of the families Acrididae and Romaleidae , from Neotropical Region, has shown a variability in distribution pattern and qualification of the CH through the C-banding and base specific fluorochromes Chromomycin A3 (CMA3) and 4’-6’-diamidino-2-fellindol (DAPI) staining. Distinct nucleolus organizing regions (NORs) locations, through the silver nitrate impregnation (AgNO3) and fluorescent in situ hybridization (FISH), have been observed in these species ( Souza et al 1998 , Loreto and Souza 2000 , Pereira and Souza 2000 , Souza et al 2003 , Loreto et al 2005 , Souza and Melo 2007 , Loreto et al 2008 ).…”

Chromosome mapping in Abracris flavolineata (De Geer, 1773) (Orthoptera) from the Iguaçu National Park – Foz do Iguaçu, Paraná, Brazil

“…There are three patterns of distribution of GC-rich blocks in grasshoppers: (i) CMA 3 + bands related to NORs location (Souza et al 1998, Loreto and Souza 2000, Rocha et al 2012); (ii) CMA 3 + in all chromosomes (Souza et al 1998, Pereira and Souza 2000); and, (iii) GC-rich blocks in some chromosomes (Loreto and Souza 2000, Souza et al 2003, Loreto et al 2005, Souza and Melo 2007, Rocha et al 2012). AT-rich heterochromatin is rarely encountered in Acrididae, as is the case Arcyptera fusca (Pallas, 1773), A. tornosi Bolívar, 1884 (Bella and Gosálvez 1991) and Dociostaurus genei (Ocskay, 1832) (Rodríguez Iñigo et al 1993).…”

Physical mapping of the Period gene on meiotic chromosomes of South American grasshoppers (Acridomorpha, Orthoptera)

“…The karyotypes of O. virens (Carvalho et al, 2011), X. discoideus angulatus (Souza et al, 1998), and S. pallens (Souza and Melo, 2007) were characterized by basic cytogenetic techniques, such as C banding and silver nitrate impregnation. In these species, 2n♂ = 23 chromosomes was found, and chromosomes were generally arranged as three pairs of large chromosomes (L1-L3), five pairs of medium chromosomes (M4-M8), three pairs of small chromosomes (S9-S11), and the X chromosome, which is considered to be a medium-sized chromosome.…”

“…The 45S rDNA was observed in dispersed sites in the karyotypes of O. virens (Carvalho et al, 2011), X. discoideus angulatus (Souza et al, 1998), S. pallens (Souza and Melo, 2007), and others. The 5S and 18S families and the histone H3 gene presented several marks on medium chromosome pairs of S. robusta and other Proscopiidae species (Cabral-deMello et al, 2011a).…”