Untitled

Abstract

Two species of Odontocheila, O. confusa and O. nodicornis, from the Neotropical Region were studied regarding their karyotypes, localisation and activity of ribosomal genes and C-banding. The species, although belonging to the same genus, have quite distinct karyotypes. O. confusa has 10 pairs of autosomes and a single sex chromosome mechanism of the XY/XX type, thus a diploid value of 2n = 22 in males and females. One aneuploid male with a diploid number of 2n = 20 and one male with three B chromosomes were found in a total of eight males studied. O. nodicornis has 17 autosomal pairs and also a single chromosome system but of the X0/XX type, thus a diploid value of 2n = 35 in males and 2n = 36 in females. Fluorescence in situ hybridisation (FISH) revealed the presence of rDNA clusters in two autosomes in both species in mitotic and meiotic figures. Silver staining of male interphase nuclei confirmed the FISH results and showed that all rDNA genes were active. C-banding analysis revealed the presence of constitutive heterochromatin in the centromeres of all chromosomes in the two species plus two pairs in O. nodicornis with terminal positive C-bands. These results are discussed from the cytogenetic and evolutionary point of view.

Cytogenetic analyses using C-banding and DAPI/CMA3 staining of four populations of the maize weevil Sitophilus zeamais Motschulsky, 1855 (Coleoptera, Curculionidae)

“…The C-banding patterns observed, as well as the absence of positive bands in the Y chromosome, corroborated literature data for most Curculionidae, as well as for several other insect species (Juan and Petitpierre 1989, Imai 1991, Rozek 1998, Almeida et al 2000, Proença et al 2002, Holecová et al 2002, 2008, 2013, Rozek et al 2004, Zacaro et al 2004, Lachowska et al 2004, 2005, 2006, 2008, 2009, Schneider et al 2007, Lachowska 2008, Kajtoch et al 2009). However, Curculionidae species with a large heterochromatic block on the genomes have been found (Holecová et al 2002, Lachowska et al 2004, 2009, Rozek et al 2004).…”

B chromosome in the beetle Coprophanaeus cyanescens (Scarabaeidae): emphasis in the organization of repetitive DNA sequences

“…In Coleoptera, the presence of B chromosomes has been described in approximately 80 species belonging to several families, including Buprestidae [18], Cantharidae [19], Cicindelidae [20] and Scarabaeidae [21,22]. In general, the studies in Coleoptera have concentrated on the presence or absence of B chromosomes in species, with few reports covering their frequency in populations and/or their molecular content [18,21-23].…”

Patterns of rDNA chromosomal localization in Palearctic Cephalota and Cylindera (Coleoptera: Carabidae: Cicindelini) with different numbers of X-chromosomes

“…Tiger beetles, in particular members of the subtribe Cicindelina , are suitable taxa to explore the link between chromosomal rearrangements and great species diversity. Cytogenetics is still a poorly developed discipline in tiger beetles, with very few cicindelid species karyotyped ( Serrano and Galián 1998 ; Galián and Hudson 1999 ; Proença et al 1999 ; Galián et al 2002 , 2007 ; Proença et al 2002a , b , 2005 ; Zacaro et al 2004 ), not exceeding about 4% of more than 2415 described taxa ( Wiesner 1992 ; Lorenz 2005 ; Pearson and Cassola 2005 ). Within the more recent tribe Cicindelini the generalized karyotype is made up of nine to eleven autosomal pairs of decreasing size ( Galián et al 1990 ), plus a sex chromosome mechanism of the XnY type, where n varies between 2 and 4 that forms a non-chiasmatic multivalent connected by telomeric proteins during meiosis ( Giers 1977 ).…”

“…Multiple sex chromosomes have been found in other taxa of the tribes Cicindelini and Collyrini ( Galián et al 1990 , 2002 , 2007 ). Single systems representing secondary loss of both X- and Y-chromosomes have been described in Cylindera germanica (XY/XX) ( Giers 1977 ), Cylindera paludosa (X0/XX)( Serrano et al 1986 ), Odontocheila confusa (XY/XX) and Odontocheila nodicornis (X0/XX) ( Proença et al 2002a ). On the other hand, single systems (XY/XX and X0/XX) have been considered as an ancestral state in the morphologically more primitive lineages, namely the tribes Megacephalini ( Serrano et al 1986 ; Galián and Hudson 1999 ; Proença et al 2002b ), Mantichorini and Omini ( Galián et al 2002 ).…”

“…Galian et al (2002) showed that more primitive lineages ( Manticorini , Omini and Megacephalini ) have a high number of rDNA loci, located exclusively in the autosomes (three and four pairs)¸ whereas more advanced lineages (tribes Collyrini and Cicindelini ) show a lower number of rDNA loci but with a variety of localization patterns. According to overall evidence these loci may be found on the autosomes (one autosomal pair), on the heterosomes (one of the X chromosomes and the Y) or in both types of chromosomes (one autosomal pair plus heterosomal copies l ocated on one of the X chromosome) ( Galián et al 1995 ; Galián and Hudson 1999 ; Galián et al 2002 ; Proença et al 2002a , b ; Proença and Galián 2003 ; Zacaro et al 2004 ). This dynamism was exemplified by the occurrence of frequent changes of the rDNA loci between autosomes and sex chromosomes in North American species of Cicindela and related taxa ( Cylindera and Cicindelidia among others) ( Galián et al 2007 ).…”