The Cytogenetic Map of the Nile Crocodile (Crocodylus niloticus, Crocodylidae, Reptilia) with Fluorescence In Situ Localization of Major Repetitive DNAs.

Tandemly arranged and dispersed repetitive DNA sequences are important structural and functional elements that make up a significant portion of vertebrate genomes. Using high throughput, low coverage whole genome sequencing followed by bioinformatics analysis, we have identified seven major tandem repetitive DNAs and two fragments of LTR retrotransposons in the genome of the Nile crocodile (Crocodylus niloticus, 2n = 32). The repeats showed great variability in structure, genomic organization, and chromosomal distribution as revealed by fluorescence in situ hybridization (FISH). We found that centromeric and pericentromeric heterochromatin of C. niloticus is composed of previously described in Crocodylus siamensis CSI-HindIII and CSI-DraI repetitive sequence families, a satellite revealed in Crocodylus porosus, and additionally contains at least three previously unannotated tandem repeats. Both LTR sequences identified here belong to the ERV1 family of endogenous retroviruses. Each pericentromeric region was characterized by a diverse set of repeats, with the exception of chromosome pair 4, in which we found only one type of satellite. Only a few repeats showed non-centromeric signals in addition to their centromeric localization. Mapping of 18S-28S ribosomal RNA genes and telomeric sequences (TTAGGG)n did not demonstrate any co-localization of these sequences with revealed centromeric and pericentromeric heterochromatic blocks.

Molecular cytological analysis of alien introgressions in common wheat lines derived from the cross of TRITICUM AESTIVUM with T. kiharae.

BACKGROUND: Triticum kiharae (AtAtGGDD, 2n = 42) is of interest for the improvement of bread wheat as a source of high grain protein and gluten content, as well as resistance to many diseases. The use of T. kiharae for the improvement of T. aestivum L. is complicated by the fact that the homology degree of their genomes is low and this leads to an unbalanced set of chromosomes in the gametes of its first generations and the elimination of some genotypes. The aim of this study was to analyze the nature of alien introgressions and their effect on the cytological stability of hybrids obtained from crossing of bread wheat varieties with T. kiharae. RESULTS: Using C-banding, the presence of entire chromosomes of T. kiharae in the karyotypes of hybrid lines (intergenomic substitution 2G/2B), chromosome arms (centric translocation Т2AtS:2AL) and large inserts in the form of terminal translocations involving chromosomes of 1st, 3rd and 5th homoeologous groups of B- and G-genomes were found. Molecular markers revealed short introgression of T. kiharae into the genome of common wheat varieties. The highest introgression frequency was shown for 1A, 1B, 2A, 5B, and 6A chromosomes, while no foreign chromatin was detected in 4A and 4B chromosomes. A high level of cytological stability (a meiotic index of 88.18-93.0%) was noted for the majority of introgression lines. An exception was found for the lines containing the structural reorganization of chromosome 5B, affecting the main genes of chromosome synapsis in terms of their functioning. CONCLUSIONS: During the stabilization of hybrid karyotypes, the introgression of genetic material from T. kiharae into the genome of T. aestivum occurs in the form of short fragments detectable only by molecular markers and in the form of whole chromosomes (intergenomic substitution) and their large fragments (centric and terminal translocations). The level of cytological stability achieved in F10 by the majority of introgression lines ensures the formation of functional gametes sufficient for the successful reproduction of the obtained hybrids.

A combined banding method that allows the reliable identification of chromosomes as well as differentiation of AT- and GC-rich heterochromatin.

Сonstitutive heterochromatin areas are revealed by differential staining as C-positive chromosomal regions. These C-positive bands may greatly vary by location, size, and nucleotide composition. CBG-banding is the most commonly used method to detect structural heterochromatin in animals. The difficulty in identification of individual chromosomes represents an unresolved problem of this method as the body of the chromosome is stained uniformly and does not have banding pattern beyond C-bands. Here, we present the method that we called CDAG for sequential heterochromatin staining after differential GTG-banding. The method uses G-banding followed by heat denaturation in the presence of formamide with consecutive fluorochrome staining. The new technique is valid for the concurrent revealing of heterochromatin position due to differential banding of chromosomes and heterochromatin composition (AT-/GC-rich) in animal karyotyping.

A Comparative Chromosome Mapping Study in Japanese Podismini Grasshoppers (Orthoptera: Acrididae: Melanoplinae).

In the present paper, karyotypes of 7 Japanese Podismini species, Anapodisma beybienkoi, Fruhstorferiola okinawaensis, Parapodisma caelestis, P. mikado, P. setouchiensis, P. tenryuensis, and Sinopodisma punctata (2n♂ = 21, all acrocentric), are described and compared on the basis of conventional (C-banding, DAPI/CMA3-staining, Ag-NOR) and molecular (FISH with 18S rDNA and telomeric probes) cytogenetic staining methods. This is the first study to report karyotypes of A. beybienkoi and P. caelestis. Differential staining techniques showed karyotypic diversity in these species. The number of 18S rDNA signals ranged from 2 to 6, and the signals were located on the autosomes or sex chromosomes. In all species, clusters of rDNA coincided with Ag-NORs. Telomeric signals occurred at the chromosome ends at the pachytene stage and seldom at other stages of meiosis. Paracentromeric and some distal and interstitial blocks of constitutive heterochromatin were detected in the chromosomes of Anapodisma, Fruhstorferiola, and Parapodisma species. Staining with DAPI and CMA3 revealed 2 groups of heterochromatin composition. In addition, intraspecific differences in the number of rDNA clusters and C-bands were observed within Parapodisma species. Based on the evidence of cytogenetic characteristics, the monophyly of Tonkinacridina cannot be supported.

Genetic classification of Aegilops columnaris Zhuk. (2n=4x=28, UcUcXcXc) chromosomes based on FISH analysis and substitution patterns in common wheat × Ae. columnaris introgressive lines.

Aegilops columnaris is a tetraploid species originated from Ae. umbellulata (2n=2x=14, UU) and a yet unknown diploid grass species. Although Ae. columnaris possesses some agronomically valuable traits, such as heat and drought tolerance and resistance to pests, it has never been used in wheat breeding because of difficulties in producing hybrids and a lack of information on the relationships between Ae. columnaris and common wheat chromosomes. In this paper, we report the development of 57 wheat - Ae. columnaris introgressive lines covering 8 of the14 chromosomes of Aegilops. Based on substitution spectra of hybrids and the results of FISH analysis of the parental Ae. columnaris line with seven DNA probes, we have developed the genetic nomenclature of the Uc and Xc chromosomes. Genetic groups and genome affinities were established for 11 of 14 chromosomes; the classification of the remaining three chromosomes remains unsolved. Each Ae. columnaris chromosome was characterized on the basis of C-banding pattern and the distribution of seven DNA sequences. Introgression processes were shown to depend on the parental wheat genotype and the level of divergence of homoeologous chromosomes. We found that lines carrying chromosome 5Xc are resistant to leaf rust; therefore, this chromosome could possess novel resistance genes that have never been utilized in wheat breeding.

A C-banded karyotype of mitotic chromosomes in diploid purple coneflower (Echinacea purpurea L.).

BACKGROUND: Aneuploid ermpglasm is an important resource for genetic studies and identification of individual chromosomes in the cells of the aneuploid is an important step. The karyotype has already been established for purple coneflower (Echinacea purpurea L.), but due to the high similarity in the morphology of several pairs of chromosomes in this species, it cannot be used to identify individual chromosomes in its own complement. The objectives of this study are to develop and evaluate the Giemsa C-banding technique for the purpose of identifying the individual chromosomes in Echinacea purpurea. RESULTS: The established karyotype with C-bands showed that all the 11 pairs of chromosomes possessed centromeric bands. Telomeric bands appeared most frequently in almost all the chromosomes with only two exceptions, the short arm of the chromosome 9 and the long arm of the chromosome 10. Intercalary bands were found mainly in the long arm of some chromosomes with only two exceptions, the chromosomes 1 and 2 that had intercalary bands on both arms. The chromosome 4 was the only chromosome where intercalary bands were absent. CONCLUSIONS: Chromosomes in E. purpurea could be stained with Giemsa to bear C-bands. By classifying the chromosomes into groups and judging the C-bands, each chromosome could be identified. The methods established in this study might be used for the identification of chromosome constitution in aneuploid E. purpurea created in a breeding program.

Cytogenetic Features of Human Head and Body Lice (Phthiraptera: Pediculidae).

The genus Pediculus L. that parasitize humans comprise two subspecies: the head lice Pediculus humanus capitis De Geer and the body lice Pediculus humanus humanus De Geer. Despite the 200 yr of the first description of these two species, there is still a long debate about their taxonomic status. Some authors proposed that these organisms are separate species, conspecifics, or grouped in clades. The sequencing of both forms indicated that the difference between them is one gene absent in the head louse. However, their chromosomal number remains to be determined. In this study, we described the male and female karyotypes, and male meiosis of head and body lice, and examined the chromatin structure by means of C-banding. In P. h. humanus and P. h. capitis, the diploid chromosome complement was 2 n = 12 in both sexes. In oogonial prometaphase and metaphase and spermatogonial metaphase, it is evident that chromosomes lack of a primary constriction. No identifiable sex chromosomes or B chromosomes were observed in head and body lice. Neither chiasmata nor chromatin connections between homologous chromosomes were detected in male meiosis. The meiotic behaviour of the chromosomes showed that they are holokinetic. C-banding revealed the absence of constitutive heterochromatin. Our results provide relevant information to be used in mapping studies of genes associated with sex determination and environmental sensing and response.

Cytogenetic and molecular markers for detecting Aegilops uniaristata chromosomes in a wheat background.

Aegilops uniaristata has many agronomically useful traits that can be used for wheat breeding. So far, a Triticum turgidum - Ae. uniaristata amphiploid and one set of Chinese Spring (CS) - Ae. uniaristata addition lines have been produced. To guide Ae. uniaristata chromatin transformation from these lines into cultivated wheat through chromosome engineering, reliable cytogenetic and molecular markers specific for Ae. uniaristata chromosomes need to be developed. Standard C-banding shows that C-bands mainly exist in the centromeric regions of Ae. uniaristata but rarely at the distal ends. Fluorescence in situ hybridization (FISH) using (GAA)8 as a probe showed that the hybridization signal of chromosomes 1N-7N are different, thus (GAA)8 can be used to identify all Ae. uniaristata chromosomes in wheat background simultaneously. Moreover, a total of 42 molecular markers specific for Ae. uniaristata chromosomes were developed by screening expressed sequence tag - sequence tagged site (EST-STS), expressed sequence tag - simple sequence repeat (EST-SSR), and PCR-based landmark unique gene (PLUG) primers. The markers were subsequently localized using the CS - Ae. uniaristata addition lines and different wheat cultivars as controls. The cytogenetic and molecular markers developed herein will be helpful for screening and identifying wheat - Ae. uniaristata progeny.

Cytogenetic and molecular identification of small-segment chromosome translocation lines from wheat-rye substitution lines to create wheat germplasm with beneficial traits.

Intergeneric crop plant hybrid lines with small-segment chromosome translocations are very useful in plant genetic research and breeding. In this study, to create small-segment chromosome translocations with beneficial agronomic characters, the progeny of wheat-rye substitution lines 5R/5A and 6R/6A were selected from generations F2 to F5 for rye-specific characteristics. A PCR primer and specific simple sequence repeat marker for rye were used in F5 populations to detect rye chromatin and to amplify a specific chromosome band in six translocation lines (06-6-5, 06-6-6, 06-6-9, 6-26-1, 7-23, and 7-33). Fragment pSc119.1 cloned from 7-33 had 99% homology with the big ear gene sequence (GenBank AF512607.1) in wheat. The six lines were further characterized via pollen mother cell meiosis analysis for genetic stability, and chromosome C-banding and genomic in situ hybridization for rye chromatin. The results show that line 7-33 was still within the 5R/5A substitution lines and possessed the big ear gene. The other lines all contained small-segment rye chromosome translocations. The results indicated that substitution line hybridization is an effective method for creating small-segment chromosome translocations with useful agronomic traits. Trials for these six wheat-rye translocation lines are justified because they possess many important stably-inherited agronomic characters, including disease resistance and improved yield.

Karyotype analysis of Quasipaaspinosa David, 1875 (Anura, Dicroglossidae) with conventional cytogenetic techniques.

The current study analyzed the chromosomal karyotype of Quasipaaspinosa David, 1875 from Hunan Province, China. The karyotype, C-banding, BrdU-banding pattern were characterized using direct preparation of bone-marrow cells and hemocyte cultures. The findings indicated that Q.spinosa was a diploid species (2n = 26) that lacked heteromorphic chromosomes and secondary constrictions. C-banding analysis revealed an abundance of positive signals in the centromere regions, while the BrdU-banding pattern showed three phases in both male and female, occurring consistently and in chronological sequence during S-phase. Notably, there was no asynchronous replication in the late phase. This study enhanced our understanding of the karyotypic structure of Q.spinosa by conventional cytogenetic techniques, thus providing essential scientific insights into the cytogenetics of Q.spinosa.

First Cytogenetic Analysis of Hemidactylus mercatorius Gray, 1842 Provides Insights on Interspecific Chromosomal Diversification in the Genus Hemidactylus (Squamata: Gekkonidae).

This contribution provides the first karyotype description of Hemidactylus mercatorius and discusses the interspecific chromosome diversification in the genus. Chromosomal analysis was performed on samples from different Malagasy populations using standard karyotyping, Ag-NOR staining, and banding methods (sequential C-banding + Giemsa, + Chromomycin A3, +4',6-diamidino-2-phenylindole). Irrespective of sex or sampling locality, H. mercatorius shows a karyotype of 2n = 42 with metacentric (1, 18-21), submetacentric (4), subtelocentric (5, 11), and acrocentric pairs (all the remaining pairs). There was no heteromorphic chromosome pair and no clear distinction between macro- and microchromosomes. NORs were localised close to the centromeres of a medium acrocentric pair (14). Heterochromatic blocks were identified on the telomeric and centromeric regions of most chromosome pairs. A comparison with the karyotype of H. mabouia highlights that the different morphology of several chromosome pairs clearly distinguishes the two species, contrasting the previously proposed synonymy. The differences between the karyotypes of H. mercatorius and H. mabouia concern the number of biarmed and acrocentric elements, suggesting the occurrence of several chromosome inversions. Considering all the available karyotype data on Hemidactylus and its sister genus Cyrtodactylus, it is possible to advance an evolutionary hypothesis on their chromosomal evolution, starting from a common ancestor with 2n = 48 and all acrocentric elements. From this ancestral condition, the karyotype diversification in the two genera has been prevalently characterised by a progressive accumulation of fusions and inversions which have reduced the total chromosome count and increased the number of biarmed chromosomes.

Chromosome Bandings and Recognition.

Chromosome banding can be defined as the lengthwise variation in staining properties along a chromosome stained with a dye. Chromosome banding became more practical in the early 1970s and is an essential technique used in karyotyping to identify human chromosomes for both clinical and research purposes. Most importantly, karyotyping is now considered a mandatory investigation of all newly diagnosed leukemias. Some banding methods, such as Giemsa (G)-, reverse (R)-, and centromere (C)-banding, still contribute greatly by being used as a routine procedure in clinical cytogenetic laboratory nowadays. Each chromosome has a unique sequence of bar code-like stripes, allowing the identification of individual homologues and the recognition of structural abnormalities through analyzing the disruption of the normal banding pattern at specific landmarks, regions, and bands as described in the ideogram. Since the quality of metaphases obtained from malignant cells is generally inferior to normal constitutional cells for karyotyping, a practical and accurate chromosome identification training guide is indispensable for a trainee or newly employed cytogenetic technologist in a cancer cytogenetic laboratory. The most common and currently used banding methods and chromosome recognition guide for distinguishable bands of each chromosome are described in detail in this chapter with an aim to facilitate quick and accurate karyotyping in cancer cells.

Initial Steps of XY Sex Chromosome Differentiation in the Armored Catfish Hypostomus albopunctatus (Siluriformes: Loricariidae) Revealed by Heterochromatin Accumulation.

In fish species, heterochromatinization is one process that could trigger sex chromosome differentiation. The present article describes a nascent XX/XY sex chromosome system evidenced by heterochromatin accumulation and microsatellite (GATA)8 in Hypostomus albopunctatus from two populations of the Paraná River basin. The specimens of H. albopunctatus from the Campo and Bossi Rivers share the same karyotype. The species exhibits 74 chromosomes (8m+14sm +16st +36a, fundamental number = 112). The C-banding technique suggests male heterogamety in H. albopunctatus, where the Y-chromosome is morphologically like the X-chromosome but differs from it for having long arms that are entirely heterochromatic. Double fluorescence in situ hybridization (FISH) with 18S and 5S rDNA probes confirmed the Ag-nucleolus organizer region sites in a single pair for both populations, and minor rDNA clusters showed interpopulational variation. FISH with the microsatellite (GATA)8 probe showed a dispersed pattern in the karyotype, accumulating these sequences of sex chromosomes of both populations. FISH with microsatellite (CGC)10 probe showed interpopulational variation. The absence of differentiated sex chromosomes in H. albopunctatus is described previously, and a new variant is documented herein where XY chromosomes can be seen in an early stage of differentiation.

Prenatal diagnosis of dicentric chromosome X mosaicism: a case report and review.

A dicentric chromosome is an abnormal chromosome with two centromeres on the same chromosome. It has been reported that dicentric chromosomes are specific biomarkers of radiation exposure, but dicentric chromosomes are rarely identified in newborns with multiple congenital anomalies. At 16 weeks of gestation, a 39-year-old pregnant woman (gravida 2, para 1) was referred to the prenatal diagnosis center for genetic counseling. The fetal ultrasonography indicated multiple anomalies. Subsequently, amniocentesis was performed, and the G-banding karyotype analysis showed a rare type of mosaicism. The C-banding karyotype analysis indicated a pseudo-dicentric chromosome X [psu dic (X; 18) (p11.2; p11.2)]. A single-nucleotide polymorphism array (SNP array) revealed three pathogenic copy number variations (CNVs). After genetic counseling, the parents chose to terminate this pregnancy. This study provides new evidence for a better understanding of the diagnosis of dicentric chromosomes and emphasizes on the importance of genetic counseling.

New insights into the chromosomes of stoneflies: I. Karyotype, C-banding and localization of ribosomal and telomeric DNA markers in Skwalacompacta (McLachlan, 1872) (Polyneoptera, Plecoptera, Perlodidae) from Siberia.

This study provides data on chromosome number (2n♂♀=26), sex determination mechanism (XY♂/XX♀), C-banding pattern, distribution of clusters of telomeric TTAGG repeats and 18S ribosomal DNA in the karyotype of the stonefly Skwalacompacta (McLachlan, 1872). For the first time in the history of stoneflies cytogenetics, we provide photos of the chromosomes of the Plecoptera insects. The karyotype of males and females of S.compacta consists of 12 pairs of autosomes. Three pairs of large autosomes and four pairs of medium-sized autosomes are subacrocentric. The remaining pairs of autosomes are small, with unclear morphology. Pericentromeric C-bands were revealed in all autosomes. The sex chromosomes are also subacrocentric. The short arms of X and Y chromosomes are entirely heterochromatic and are rich in ribosomal DNA sequences. In the X chromosome this arm is larger than in the Y chromosome. It is likely that this arm associated with the nucleolar organizer (NOR). Telomeric DNA (TTAGG)n repeats were detected in the terminal regions of all chromosomes.

Karyotypic conservatism in five species of Prochilodus (Characiformes, Prochilodontidae) disclosed by cytogenetic markers.

The family Prochilodontidae is considered a group with well conserved chromosomes characterized by their number, morphology and banding patterns. Thence, our study aimed at accomplishing a cytogenetic analysis with conventional methods (Giemsa staining, silver staining of the nucleolus organizer regions-AgNOR, and C-banding) and fluorescence in situ hybridization (FISH) with 18S and 5S ribosomal DNA probes in five species of the Prochilodus genus (Prochilodus argenteus, Prochilodus brevis, Prochilodus costatus, Prochilodus lineatus and Prochilodus nigricans) collected from different Brazilian hydrographic basins. The results revealed conservatism in chromosome number, morphology, AgNORs 18S and 5S rDNAs location and constitutive heterochromatin distribution patterns. The minor differences observed in this work, such as an Ag-NOR on a P. argenteus chromosome and a distinct C-banding pattern in P. lineatus, are not sufficient to question the conservatism described for this group. Future work using repetitive DNA sequences as probes for FISH will be interesting to further test the cytogenetic conservatism in Prochilodus.

Cytogenetic Analysis of Seven Species of Gekkonid and Phyllodactylid Geckos.

Geckos (Gekkota), the species-rich clade of reptiles with more than 2200 currently recognized species, demonstrate a remarkable variability in diploid chromosome numbers (2n = 16-48) and mode of sex determination. However, only a small fraction of gekkotan species have been studied with cytogenetic methods. Here, we applied both conventional (karyotype reconstruction and C-banding) and molecular (fluorescence in situ hybridization with probes for rDNA loci and telomeric repeats) cytogenetic analyses in seven species of geckos, namely Blaesodactylus boivini, Chondrodactylus laevigatus, Gekko badenii, Gekko cf. lionotum, Hemidactylus sahgali, Homopholis wahlbergii (Gekkonidae) and Ptyodactylus togoensis (Phyllodactylidae), in order to provide further insights into the evolution of karyotypes in geckos. Our analysis revealed the presence of interstitial telomeric repeats in four species, but we were not able to conclude if they are remnants of previous chromosome rearrangements or were formed by an accumulation of telomeric-like satellite motifs. Even though sex chromosomes were previously identified in several species from the genera Hemidactylus and Gekko by cytogenetic and/or genomic methods, they were not detected by us in any examined species. Our examined species either have poorly differentiated sex chromosomes or, possibly, environmental sex determination. Future studies should explore the effect of temperature and conduct genome-wide analyses in order to identify the mode of sex determination in these species.

Dicentric Recombinant Chromosome 18 due to Maternal Paracentric Inversion Analyzed by Array CGH.

Introduction: Chromosomal abnormalities are mostly found in 0.5-0.8% of live-born infants with developmental and morphological defects. Paracentric inversions are structural intrachromosomal rearrangements resulting in a risk of chromosomally unbalanced gametes in carriers. Case Presentation: Herein, we report a patient with dicentric rearrangement of chromosome 18 due to maternal paracentric inversion of chromosome 18. The patient was a girl, aged 3 years and 11 months. She was referred due to multiple congenital abnormalities, severe intellectual disability, and motor retardation. She had microcephaly, prominent metopic suture, synophrys, epicanthic folds, telecanthus, wide-set alae nasi, wide columella, bilateral cleft lip and palate, pectus carinatum, umbilical hernia, pes planus, and anteriorly displaced anus. She had bilateral external auditory canal stenosis and mild right-sided and moderate left-sided sensorineural hearing loss. Echocardiography showed secundum-type atrial septal defect and mild tricuspid failure. Brain magnetic resonance imaging showed only thinning of posterior areas of the corpus callosum. Chromosome analysis showed 46,XX,dic rec(18) by GTG and C banding. Dicentric chromosome was confirmed by fluorescence in situ hybridization analysis. Paternal karyotype was normal 46,XY but maternal chromosome analysis showed a paracentric inversion in chromosome 18 with 46,XX,inv(18)(q11.2?q21.3?) karyotype. Array CGH was performed on a peripheral blood sample from the patient and showed duplication at 18p11.32p11.21 and 18q11.1q11.2, and deletion at 18q21.33q23. The patient's final karyotype is arr 18p11.32p11.21(64,847_15,102,598)×3,18q11.1q11.2(18,542,074_22,666,470)×3,18q21.33q23(59,784,364_78,010,032)×1. Discussion: To the best of our knowledge, this is the first report of a patient with dicentric chromosome 18 due to a parental paracentric inversion of chromosome 18. We present the genotype-phenotype correlation with literature review.

Molecular cytological analysis of alien introgressions in common wheat lines created by crossing of Triticum aestivum with T. dicoccoides and T. dicoccum.

Wild and domesticated emmer (ВВАА, 2n = 28) are of significant interest for expanding the genetic diversity of common wheat as sources of a high protein and microelement grain content, resistance to many biotic and abiotic factors. Particular interest in these species is also determined by their close relationship with Triticum aestivum L., which facilitates interspecific hybridization. The objective of this work was to analyze the nature of alien introgressions in hybrid lines from crossing common wheat varieties with T. dicoccoides and T. dicoccum, and to assess the effect of their genome fragments on the cytological stability of introgression lines. A C-banding technique and genotyping with SNP and SSR markers were used to determine localization and length of introgression fragments. Assessment of cytological stability was carried out on the basis of chromosome behavior in microsporogenesis. A molecular cytogenetic analysis of introgression wheat lines indicated that the inclusion of the genetic material of wild and domesticated emmer was carried out mainly in the form of whole arms or large fragments in the chromosomes of the B genome and less extended inserts in the A genome. At the same time, the highest frequency of introgressions of the emmer genome was observed in chromosomes 1A, 1B, 2B, and 3B. The analysis of the final stage of meiosis showed a high level of cytological stability in the vast majority of introgression wheat lines (meiotic index was 83.0-99.0 %), which ensures the formation of functional gametes in an amount sufficient for successful reproduction. These lines are of interest for the selection of promising material with agronomically valuable traits and their subsequent inclusion in the breeding process.

A DAPI-Based Modified C-banding Technique for a Rapid Achieving High Photographic Contrast of Centromeres on Chromosomes.

Many chromosome assays rely on the quantification of chromosome abnormalities in cells, and one important abnormality is the existence of more than one centromere for each chromosome. The quantification of such abnormalities has been studied before. However, this process is labor-intensive and time consuming. Thus, this assay is challenging for ex-laboratory applications, where speed is required. We present a visualization method that uses a cheap stain-DAPI, long (e.g., high-resolution) chromosomes and our modified C-banding method for labeling chromosomes. The labeled chromosomes can then be easily seen with a conventional and readily available fluorescence microscopy system. This method achieves an acceleration of the detection of the presence of constitutive heterochromatin in chromosomal centromeres by more than 10 times, to ~2 h, in Human lymphocyte cells and in cells of the human Jurkat line. This new procedure will ultimately provide an easier and cheaper alternative to FISH/PNA probes, or the classic Giemsa staining method. Simplification and reduction in time of the overall procedure will enable the utilization of centromere-counting assays in laboratory and ex-laboratory applications, including in emergency response.