Crossing two parental plants carrying two types of extra chromosomes, 2n+2(5L*7S) by 2n+3(2S*2S) permitted effective selection for individuals with up to eight 2S*2S chromosomes in later generations. The crossing of 2n + 3(2S*2S) by 2n+1( 8S*8L) and by the wild tomato relative, diploid L. pimpinellifolium , produced plants with up to four extra chromosomes. The tolerance of 2S*2S chromosomes th...

The organization of chromosomes is important for various biological processes and is involved in the formation of rearrangements often observed in cancer. In mammals, chromosomes are organized in territories that are radially positioned in the nucleus. However, it remains unclear whether chromosomes are organized relative to each other. Here, we examine the nuclear arrangement of 10 chromosomes...

Karyotypic data are presented for two sympatric Corydoras species of the Lagoa Dourada, namely, C. ehrhadti and C. paleatus, which are found in the upper Tibagi river basin (Ponta Grossa, State of Paraná, Brazil). The same diploid number and karyotypic formula were observed in both species/populations. A great similarity in the constitutive heterochromatin distribution and in the activity of nu...

Molecular studies of six species from the ancient extant seed plant Cycas, covering a wide range of its morphological diversity and all major areas of distribution, revealed a high level of intra-individual polymorphism of the internal transcribed spacer (ITS1, 5.8S, and ITS2) region, indicative of incomplete nrDNA concerted evolution. Through a range of comparisons of sequence characteristics ...

We present the karyotypic characterization of 26 specimens of the side-necked turtle Hydromedusa tectifera collected in the upper Iguaçu River, Paraná state, Brazil. The turtles were cytogenetically analyzed using Giemsa staining and other banding techniques (C, G, Ag-NOR and CMA3) as well as fluorescence in situ hybridization (FISH) with a rDNA 18S probe. All the specimens showed a diploid num...

BACKGROUND The health risks of crack cocaine smoking on the oral mucosa has not been widely researched and documented. OBJECTIVE The purpose of this study was to analyze the proliferative activity of oral epithelial cells exposed to crack cocaine smoke using silver nucleolar organizer region (AgNOR) staining. METHODS Oral smears were collected from clinically normal-appearing buccal mucosa ...

The saturation values for ribosomal RNA hybridization have been determined for DNA from diploid and polytene tissues of Drosophila melanogaster. These values have been measured in XO and XX larvae which have, respectively, one and two nucleolus organizers in the diploid chromosome set. The results show that (1) in diploid cells the ribosomal (r)DNA is present in amounts proportional to the numb...

The nuclear pore complex proteins SonA and SonB, the orthologs of mammalian RAE1 and NUP98, respectively, were identified in Aspergillus nidulans as cold-sensitive suppressors of a temperature-sensitive allele of the essential mitotic NIMA kinase (nimA1). Subsequent analyses found that sonB1 mutants exhibit temperature-dependent DNA damage sensitivity. To understand this pathway further, we per...

Here we present a high-resolution cytogenomic analysis of chicken microchromosome 16. We established the location of the major histocompatibility complex (MHC)-B and -Y subregions relative to each other and to the nucleolus organizer region (NOR) encoding the 18S-5.8S-28S ribosomal DNA. To do so, we employed multicolor fluorescence in situ hybridization using large-insert bacterial artificial c...