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Abstract

When surveying the karyotype diversity of European loaches of the genus Cobitis to identify species involved in hybrid polyploid complexes, an extensive polymorphism in number and location of NORs was discovered in C. vardarensis using Ag-staining, C-banding, CMA3-fluorescence and fluorescence in situ hybridization (FISH). This species had 2n = 50, the karyotype contained 13 pairs of metacentric, 10 pairs of submetacentric and two pairs of subtelocentric chromosomes. The NOR-bearing chromosomes included one medium-sized metacentric pair with a large CMA3-positive heterochromatic pericentromeric block, one small metacentric as well as one large submetacentric pairs. Ribosomal sites were always located in telomeres of these chromosomes. Each of the pair of NOR-bearing chromosomes occurred in three variants - (1) presence and/or (2) absence of NORs on both homologues and (3) heterozygous combination where only one of the homologues bears NORs. Altogether, 10 different NOR cytotypes from 27 theoretically possible ones were discovered among 20 indviduals examined. The number of NORs ranged from two to five per specimen. The results regarding the number and locations of NORs as revealed by banding techniques were confirmed using FISH with rDNA probe. NOR sites were of CMA3-positive, suggesting that ribosomal sites are associated with GC-rich DNA. Very similar structural polymorphism with multiple NORs is expressed in the Danubian loach C. elongatoides indicating a close relationship between both species.

Chromosomal Analyses of <i>Cobitis phrygica</i> Battalgazi, 1944 and <i>C. simplicispina</i> Hanko, 1925 (Teleostei, Cobitidae)

“…However, there are some differences in the chromosome morphology (Boron 2000). As reported in other Cobitis species (Rabova et al 2001, Değer 2011, Esmaeili et al 2015 sex chromosome was not determined in C. phrygica and C. simplicispina. C-bands contain transcriptionally inactive highly repetitive DNA sequences (Sumner 1972, Boron 2000.…”

“…Consequently, FN of C. phrygica is lower than C. elazigensis while FN of C. simplicispina is higher than C. elazigensis. C. phrygica and C. simplicispina have the same chromosome number with C. calderoni, C. elongatoides, C. linea, C. maroccana, C. taurica and C. vardarensis (Madeira et al 1992, Rab et al 2000, Rabova et al 2001, Janko et al 2005, Esmaeili et al 2015. Nevertheless, st-a chromosomes of C. elongatoides, C. linea, C. taurica and C. vardarensis are lower than C. phrygica and C. simplicispina.…”

“…C-bands contain transcriptionally inactive highly repetitive DNA sequences (Sumner 1972, Boron 2000. C. phrygica and C. simplicispina are resemble to C. elazigensis in terms of the localization of C-bands on the centromeric regions of almost all chromosomes (Değer 2011) and to C. vardarensis which has pericentromeric C-bands on all chromosomes (Rabova et al 2001) and to C. taenia which has pericentromeric C-bands on several m-sm chromosomes (Boron 1999). C. phrygica and C. simplicispina also show similarity with S. aurata that centromeric C-bands on some chromosomes have been reported before (Boron 2000).…”

Chromosome Mapping of Repetitive Sequences in Rachycentron canadum (Perciformes: Rachycentridae): Implications for Karyotypic Evolution and Perspectives for Biotechnological Uses

“…Whereas the first contained high GC levels and replication at the onset of the S phase, the remaining heterochromatic portions showed late replication and CMA 3 /DAPI staining neutrality. However, examples of nonheterochromatinized ribosomal sites are also present in different fish groups (e.g., Fujiwara et al [49]; Ráb et al [52]; Rábová et al [53]).…”

Variability of NOR patterns in European water frogs of different genome composition and ploidy level

“…silver, chromomycin A 3 and Propidium Iodide (PI) staining, and fluorescent in situ hybridization with 28S rDNA probe commonly used in comparative studies of cold-blooded vertebrates: fish (Sola et al 1992, Ráb et al 1996, Boroń 1999, Rábová et al 2001, 2003, Kirtiklis et al 2010) and amphibians (Schmid 1982, Schmid et al 1995). The aim of our study was to investigate the variability of NOR distribution patterns in metaphase chromosomes and interphase nuclei in water frogs, especially hybrid P. esculentus of various ploidy and genome composition.…”