First constitutive heterochromatin characterization and Karyotype of white stork Ciconia ciconia (Aves: Ciconiidae)

The karyotype and constitutive heterochromatin pattern of the white stork Ciconia ciconia samples obtained from Manzala lake, Dimiaat, Egypt was described. Somatic cells of Ciconia ciconia samples have diploid number 2n= 68 chromosomes. Out of 68 chromosomes, 11 pairs including sex chromosomes were macrochromosomes and the remaining pairs were microchromosomes. Of the 11 macrochromosome pairs, no.1, 2, 4 and 5 were submetacentric and pairs no. 6, 7 and 8 were described as metacentric. In addition, the autosome pair no.3 was subtelocentric, while autosome pair no.9 was acrocentric. Also, the sex chromosome Z represents the fourth one in size and it was classified as submetacentric while, W chromosome appeared as medium size and was acrocentric. Furthermore, C-banding pattern (constitutive heterochromatin) revealed variation in their sizes and occurrence between macrochromosomes. Pairs no. 7 and 8 of autosomes exhibited unusual distribution of heterochromatin, where they appeared as entirely heterochromatic. This may be related to the origin of sex chromosomes Z and W. However, there is no sufficient evidence illustrate the appearance of entirely heterochromatic autosomes. Therefore, there is no available cytogenetic literature that describes the C-banding and karyotype of Ciconia Ciconia, so the results herein are important and may assist in cytogenetic study and evolutionary pattern of Ciconiiformes.

Karyotype, C-band and NOR phenotype of Anatolian endemic fish Squalius anatolicus (Bogutskaya, 1997) (Teleostei, Leuciscidae)

The karyotype and distribution of constitutive heterochromatin and nucleolus organizer regions (NORs) of Anatolian leuciscine endemic to Lake Beysehir, Squalius anatolicus (Bogutskaya, 1997) were analyzed respectively using conventional Giemsa-staining, C-banding and Ag-impregnation. Diploid chromosome number was 2n = 50 and karyotype consisted of 7 pairs of metacentric, 13 pairs of submetacentric, 5 pairs of subtelo- to acrocentric chromosomes, NF value equaled 90. Heteromorphic elements indicating sex chromosomes were not detected. C-banding revealed clear pericentromeric constitutive heterochromatin blocks in several chromosomes. Ag-impregnation revealed the size heteromorphism of NORs that covered almost the entire short arms of the middle-sized submetacentric chromosome pair. The karyotype pattern and simple NOR phenotype of S. anatolicus are nearly identical with that found not only in Squalius species analyzed to date but also in many other representatives of the Eurasian leuciscine cyprinids, which indicates remarkable chromosome stasis in this leuciscid lineage.

New Data on Comparative Cytogenetics of the Mouse-Like Hamsters (Calomyscus Thomas, 1905) from Iran and Turkmenistan

The taxonomy of the genus Calomyscus remains controversial. According to the latest systematics the genus includes eight species with great karyotypic variation. Here, we studied karyotypes of 14 Calomyscus individuals from different regions of Iran and Turkmenistan using a new set of chromosome painting probes from a Calomyscus sp. male (2n = 46, XY; Shahr-e-Kord-Soreshjan-Cheshme Maiak Province). We showed the retention of large syntenic blocks in karyotypes of individuals with identical chromosome numbers. The only rearrangement (fusion 2/21) differentiated C. elburzensis, C. mystax mystax, and Calomyscus sp. from Isfahan Province with 2n = 44 from karyotypes of C. bailwardi, Calomyscus sp. from Shahr-e-Kord, Chahar Mahal and Bakhtiari-Aloni, and Khuzestan-Izeh Provinces with 2n = 46. The individuals from Shahdad tunnel, Kerman Province with 2n = 51–52 demonstrated non-centric fissions of chromosomes 4, 5, and 6 of the 46-chromosomal form with the formation of separate small acrocentrics. A heteromorphic pair of chromosomes in a specimen with 2n = 51 resulted from a fusion of two autosomes. C-banding and chromomycin A3-DAPI staining after G-banding showed extensive heterochromatin variation between individuals.

A universal karyotypic system for hexaploid and diploid Avena species brings oat cytogenetics into the genomics era

Background The identification of chromosomes among Avena species have been studied by C-banding and in situ hybridization. However, the complicated results from several cytogenetic nomenclatures for identifying oat chromosomes are often contradictory. A universal karyotyping nomenclature system for precise chromosome identification and comparative evolutionary studies would be essential for genus Avena based on the recently released genome sequences of hexaploid and diploid Avena species. Results Tandem repetitive sequences were predicted and physically located on chromosomal regions of the released Avena sativa OT3098 genome assembly v1. Eight new oligonucleotide (oligo) probes for sequential fluorescence in situ hybridization (FISH) were designed and then applied for chromosome karyotyping on mitotic metaphase spreads of A. brevis, A. nuda, A. wiestii, A. ventricosa, A. fatua, and A. sativa species. We established a high-resolution standard karyotype of A. sativa based on the distinct FISH signals of multiple oligo probes. FISH painting with bulked oligos, based on wheat-barley collinear regions, was used to validate the linkage group assignment for individual A. sativa chromosomes. We integrated our new Oligo-FISH based karyotype system with earlier karyotype nomenclatures through sequential C-banding and FISH methods, then subsequently determined the precise breakage points of some chromosome translocations in A. sativa. Conclusions This new universal chromosome identification system will be a powerful tool for describing the genetic diversity, chromosomal rearrangements and evolutionary relationships among Avena species by comparative cytogenetic and genomic approaches.

Chromosome and Molecular Analyses Reveal Significant Karyotype Diversity and Provide New Evidence on the Origin of Aegilops columnaris

Aegilops columnaris Zhuk. is tetraploid grass species (2n = 4x = 28, UcUcXcXc) closely related to Ae. neglecta and growing in Western Asia and a western part of the Fertile Crescent. Genetic diversity of Ae. columnaris was assessed using C-banding, FISH, nuclear and chloroplast (cp) DNA analyses, and gliadin electrophoresis. Cytogenetically Ae. columnaris was subdivided into two groups, C-I and C-II, showing different karyotype structure, C-banding, and FISH patterns. C-I group was more similar to Ae. neglecta. All types of markers revealed significant heterogeneity in C-II group, although group C-I was also polymorphic. Two chromosomal groups were consistent with plastogroups identified in a current study based on sequencing of three chloroplast intergenic spacer regions. The similarity of group C-I of Ae. columnaris with Ae. neglecta and their distinctness from C-II indicate that divergence of the C-I group was associated with minor genome modifications. Group C-II could emerge from C-I relatively recently, probably due to introgression from another Aegilops species followed by a reorganization of the parental genomes. Most C-II accessions were collected from a very narrow geographic region, and they might originate from a common ancestor. We suggest that the C-II group is at the initial stage of species divergence and undergoing an extensive speciation process.

Chromosome and Molecular Analyses Reveal Significant Intraspecific Karyotype Diversity and Provide New Evidence on the Origin of Tetraploid Grass Aegilops columnaris

Aegilops columnaris Zhuk. is tetraploid grass species (2n=4x=28, UcUcXcXc) closely related to Ae. neglecta and growing in Western Asia and a western part of the Fertile Crescent. Genetic diversity of Ae. columnaris was assessed using C-banding, FISH, nuclear and chloroplast (cp)DNA analyses, and gliadin electrophoresis. Cytogenetically Ae. columnaris was subdivided into two groups, C-I and C-II, showing different karyotype structure, C-banding and FISH patterns. Group C-I was more similar to Ae. neglecta. All types of markers revealed significant heterogeneity of the C-II group, although group C-I was also polymorphic. Two chromosomal groups were consistent with plastogroups identified in a current study based on sequencing of three chloroplast intergenic spacer regions. The similarity of group C-I of Ae. columnaris with Ae. neglecta and their distinctness from C-II indicate that divergence of the C-I group was associated with minor genome modifications. Group C-II could emerge from C-I relatively recently, probably due to introgression from another Aegilops species followed by a reorganization of the parental genomes. Most C-II accessions were collected from the very narrow geographic region, and they might originate from a common ancestor. We suggest that the C-II group is at the initial stage of species divergence and undergoing an extensive speciation process.

A universal karyotypic system for hexaploid and diploid Avena species brings oat cytogenetics into the genomics era

Background The identification of chromosomes among Avena species have been studied by C-banding and in situ hybridization. However, the complicated results from several cytogenetic nomenclatures for identifying oat chromosomes are often contradictory. A universal karyotyping nomenclature system for precise chromosome identification and comparative evolutionary studies would be essential for genus Avena based on the recently released genome sequences of hexaploid and diploid Avena species. Results Tandem repetitive sequences were predicted and physically located on chromosomal regions of the Avena sativa genomes. Thirteen new oligonucleotide (oligo) probes for sequential fluorescence in situ hybridization (FISH) were designed and then applied for chromosome karyotyping on mitotic metaphase spreads of eleven hexaploid and diploid Avena accessions. We established a high resolution standard karyotype of A. sativa based on the distinct FISH signals of multiple oligo probes. FISH painting with bulked oligos, based on wheat-barley collinear regions, was used to validate the linkage group assignment for individual A. sativa chromosomes. We integrated our new Oligo-FISH based karyotype system with earlier karyotype nomenclatures through sequential C-banding and FISH methods, then subsequently determined the precise breakage points of some chromosome translocations. Conclusion This new universal chromosome identification system will be a powerful tool for describing the genetic diversity, chromosomal rearrangements and evolutionary relationships among Avena species by comparative cytogenetic and genomic approaches.

Karyology of Rhodeus amarus (Block, 1782) (Teleostei, Acheilognathidae) from Turkey

The aim of this study was to determine chromosomal characteristics of Rhodeus amarus (Block, 1782) from Turkey by conventional procedures (Giemsa, C-banding and Ag-NOR staining). Metaphase chromosomes were obtained from the head kidney cells. The diploid number was found as 48 and the fundamental number as 76. Chromosomes were morphologically characterized as metacentric (four pairs), submetacentric (10 pairs) and subtelo-acrocentric (10 pairs). C-bands were found to occur on the pericentromeric regions of most of the chromosomes and a single AgNOR was observed on Silver stained metaphases. The results may expand the knowledge on chromosomal features of bitterlings.