Molecular Cytogenetic Studies Research Articles

Optimization of the sperm processing protocol for subsequent molecular cytogenetic studies.

One of the causes of spontaneous pregnancy termination, infertility, and birth of children with development delay and malformations are chromosomal abnormalities (CA) as well as spontaneous aneuploidies in gametes of phenotypically normal parents. Often couples with reproductive problems, as well as spouses one of whom is a carrier of CA, turn to the programs of assisted reproductive technologies (ART) for preimplantation evaluation of the zygote chromosomal status. As part of ART programs, parental gametes are examined to assess the level of spontaneous aneuploidy. As a rule, the most accessible material for analysis is the ejaculate. Fluorescent in situ hybridization (FISH) is used to examine male gametes obtained from the ejaculate. However, this FISH-analysis has a number of limitations and difficulties because of the peculiarities of the sperm head structure, namely the supercondensed state of chromosome chromatin. In order to optimize the FISH protocol, five different protocols were used for pre-hybridization processing of ejaculate samples obtained from nine phenotypically normal men. A comparative analysis of hybridization efficiency showed that the protocol using tris(2-carboxyethyl)phosphine hydrochloride (TCEP) as a decondensation agent was the most effective for subsequent molecular cytogenetic studies. The developed hybrid protocol combining proteolytic pretreatment, TCEP and thermal decondensation can be used when other protocols for pre-hybridization treatment of ejaculate preparations are not effective.

Using carrot centromeric repeats to study karyotype relationships in the genus Daucus (Apiaceae)

BackgroundIn the course of evolution, chromosomes undergo evolutionary changes; thus, karyotypes may differ considerably among groups of organisms, even within closely related taxa. The genus Daucus seems to be a promising model for exploring the dynamics of karyotype evolution. It comprises some 40 wild species and the cultivated carrot, a crop of great economic significance. However, Daucus species are very diverse morphologically and genetically, and despite extensive research, the taxonomic and phylogenetic relationships between them have still not been fully resolved. Although several molecular cytogenetic studies have been conducted to investigate the chromosomal structure and karyotype evolution of carrot and other Daucus species, detailed karyomorphological research has been limited to carrot and only a few wild species. Therefore, to better understand the karyotype relationships within Daucus, we (1) explored the chromosomal distribution of carrot centromeric repeats (CentDc) in 34 accessions of Daucus and related species by means of fluorescence in situ hybridization (FISH) and (2) performed detailed karyomorphological analysis in 16 of them.ResultsWe determined the genomic organization of CentDc in 26 accessions of Daucus (belonging to both Daucus I and II subclades) and one accession of closely related species. The CentDc repeats were present in the centromeric regions of all chromosomes of 20 accessions (representing 11 taxa). In the other Daucus taxa, the number of chromosome pairs with CentDc signals varied depending on the species, yet their centromeric localization was conserved. In addition, precise chromosome measurements performed in 16 accessions showed the inter- and intraspecific karyological relationships among them.ConclusionsThe presence of the CentDc repeats in the genomes of taxa belonging to both Daucus subclades and one outgroup species indicated the ancestral status of the repeat. The results of our study provide useful information for further evolutionary, cytotaxonomic, and phylogenetic research on the genus Daucus and may contribute to a better understanding of the dynamic evolution of centromeric satellites in plants.

Molecular Cytogenetic Study in Patients with Acute Lymphoblastic Leukemia (ALL) in Erbil Province

Background: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and is also important in older adults. Chromosome number or structure abnormalities are seen in approximately 90% of children and 70% of adult patients with ALL. The aim of this study was to determine the prevalence of these chromosomal abnormalities in ALL patients using Fluorescence in situ Hybridization (FISH) technique and to define the frequency of chromosomal abnormalities of ALL patients in adults and children in Erbil Province. Methods: In this cross-sectional study, we evaluated karyotype results in blood samples, that collected from 55 patients with ALL (in both sexes) in Nanakaly Hospital in Erbil Province. Thirty healthy individuals were selected as the control group. Patients ages ranged between 1 to 63 years old. The samples were centrifuged to extract nucleated cells. The cells were then subjected to hypotonic shock, fixed with methanol and acetic acid. A cell suspension was then prepared for FISH technique. After examining the samples with fluorescent microscope, the obtained data along with demographic and baseline characteristics of patients were entered in SPSS software, then statistically analyzed. Results: The prevalence of chromosomal abnormalities among ALL group was 52.7% (n = 29). Of these, 31¬% (9 people) had abnormalities in chromosome number and 69¬% (20 people) had abnormalities in chromosome structure. The most common chromosomal abnormality was translocation t (9; 22), which accounted for 31¬% of all abnormalities and its prevalence among ALL patients was 16.4¬%. Clonal trisomy and t (12; 21) also accounted for 13.8% and 10.3% of abnormalities, respectively. Clonal trisomy was the most common abnormality in chromosome number, accounting for 44.4% (n = 4) of abnormalities. Only one patient with single chromosome X (X0) pattern was observed in patients. There was no significant (P> 0.05) relationship between the incidence of chromosomal abnormalities with gender, family history, history of surgery and bacterial infection, occupation, place of residence, smoking and blood type as stated from the questionnaire form. Conclusion In the current study, concluded that at least one chromosomal abnormality was found in more than half of all patients with ALL. Structural abnormalities were more common than chromosome number abnormalities. Normal karyotype was more frequent in this current study. The frequencies of some cytogenetic abnormalities such as hyperdiploidy and t (9;22) in the current study findings were comparable to those reported in the literature. The results of this study in Erbil Province can be used as baseline information for treatment decision and research purposes in ALL patients. We recommend the use of advanced molecular techniques in the future to better elucidate cryptic cytogenetic abnormalities.

Primer reporte sobre identificación del locus 5s rADN en cromosomas de Physalis peruvianaL.

Physalis peruviana (Golden berry) a native fruit of Peru, is an important Andean agricultural crop. Although classical cytogenetics research on this berry has been conducted there is no precise evidence based on molecular cytogenetic studies. The Fluorescent In Situ Hybridization (FISH) technique was applied to reveal 5S rDNA sites in chromosomes of San Pablo and Celendín populations, Cajamarca, Perú. This research was identified the 5S rDNA locus in the two populations of Golden berry, reporting six signals in 3 pairs of chromosomes which would indicate that the species is polyploid. Likewise, no differences were found in the number of 5S rDNA loci between both populations, so we could point out that they would not be different ecotypes.

Identification of Alien Chromosome/Chromatin Introgressions in Triticale × Wheat Derived Stable Lines Through Molecular Cytogenetic Analysis

Molecular cytogenetic study was conducted for identifying rye chromosome/chromatin translocation, substitution and addition in 43 triticale x wheat derived stable lines (BC1F7 and F7 generations) six different crosses using FISH (Fluorescence in situ hybridization) and GISH (Genomic in situ hybridization) analyses with different probes. Rye chromosomes/chromatin was identified in 17 BC1F7 and 12 F7 lines by these two analyses. The GISH and FISH techniques worked satisfactorily for identifying the presence of rye chromatin at metaphase. All the lines were associated with alien chromosome translocation, addition or substitution except a few lines. Most of the recombinants present in TW 1, TW 2 and TW 6 crosses were observed to be associated with important alien chromatin translocation like 1BL/1RS, substitutions 1R (1D), 5R (5D) and combination of both i.e., 1BL/1RS + 5R (5D) and in some cases presence of more than 4 rye chromosomes. The crosses TW 3 and TW 5 possessed 8 to 14 rye chromosomes in their chromosome constitution. So, their morphological expression was similar to triticale. These reconstituted lines will be of immense application for the future wheat breeding programmes.

Evolution of Tandemly Arranged Repetitive DNAs in Three Species of Cyprinoidei with Different Ploidy Levels

Polyploid species represent a challenge for both cytogenetic and genomic studies due to their high chromosome numbers and the morphological similarity between their paralogous chromosomes. This paper describes the use of low-coverage high-throughput sequencing to identify the 14 most abundant tandemly arranged repetitive elements in the paleotetraploid genome of the crucian carp (Carassius carassius, 2n = 100). These repetitive elements were then used for molecular cytogenetic studies of a closely related functionally triploid form of the Prussian carp (Carassius gibelio, 3n = 150 + Bs) and a relatively distant diploid species, the tench (Tinca tinca, 2n = 48). According to their distribution on the chromosomes of the 3 aforementioned species, the repetitive elements here identified can be divided into 5 groups: (1) those specific to a single genomic locus in both Carassius species, despite the recent carp-specific genome duplication; (2) those located in a single genomic locus of T. tinca, but amplified in one or both Carassius species; (3) those massively amplified in the B chromosomes of C. gibelio; (4) those located in a single locus in C. gibelio, but amplified in many blocks in C. carassius; and (5) those located in multiple pericentromeric loci in both Carassius species. Our data indicate that some of the repetitive elements are highly conserved in cyprinoid species and may serve as good cytogenetic and genomic markers for discriminating paralogous chromosomes, while others are evolutionarily recent, and their amplification may be related to the last whole-genome duplication event.

Molecular Cytogenetic Characterization of the Murine Melanoma Cell Lines S91 Clone M3 and B16-F1 with Variant B16-4A5

Melanoma is considered to be one of the most aggressive human tumors. Thus, early molecular diagnosis with risk factor stratification could be an efficacious strategy to increase the survival rates in affected patients. Murine cell lines B16-F1, B16-4A5, and S91 clone M3 are the ones most commonly applied in melanoma research. However, genetic peculiarities of these 3 cell lines have not been studied in detail before. Here, we closed this gap by molecular cytogenetic and array-comparative genomic hybridization studies and the translation of the characterized imbalances into the human genome. This study revealed severely rearranged karyotypes with in parts similar imbalances for all 3 cell lines. Interestingly, they involve genes known to play major roles in human melanoma. These are specifically the oncogenes and tumor suppressor genes, being associated with aggressive forms of melanoma. B16-F1, B16-4A5, and S91 clone M3 revealed aberrations which were similarly observed in human eye and skin but not in human uveal melanoma. Thus, they can be considered as model systems for advanced eye and skin melanoma.

Chromosomal evolution in Raphicerus antelope suggests divergent X chromosomes may drive speciation through females, rather than males, contrary to Haldane's rule

Chromosome structural change has long been considered important in the evolution of post-zygotic reproductive isolation. The premise that karyotypic variation can serve as a possible barrier to gene flow is founded on the expectation that heterozygotes for structurally distinct chromosomal forms would be partially sterile (negatively heterotic) or show reduced recombination. We report the outcome of a detailed comparative molecular cytogenetic study of three antelope species, genus Raphicerus, that have undergone a rapid radiation. The species are largely conserved with respect to their euchromatic regions but the X chromosomes, in marked contrast, show distinct patterns of heterochromatic amplification and localization of repeats that have occurred independently in each lineage. We argue a novel hypothesis that postulates that the expansion of heterochromatic blocks in the homogametic sex can, with certain conditions, contribute to post-zygotic isolation. i.e., female hybrid incompatibility, the converse of Haldane’s rule. This is based on the expectation that hybrids incur a selective disadvantage due to impaired meiosis resulting from the meiotic checkpoint network’s surveillance of the asymmetric expansions of heterochromatic blocks in the homogametic sex. Asynapsis of these heterochromatic regions would result in meiotic silencing of unsynapsed chromatin and, if this persists, germline apoptosis and female infertility.

Synovial Sarcoma: Ãâë Triple Sign Ãâû MRI Pattern

The synovial sarcoma (Figure 1) is a soft tissue tumour, first described by Jaffe in 1941 as a tumour that grows from the synovium of joints, bursae or tendon sheaths. It was later reported that it grew from undifferentiated mesenchymal cells. It can be localized or diffuse, intra or extra articular, with predominance in lower extremities, with the thigh as the most common location, followed by the popliteal fossa. It is usually diagnosed in adolescents or young adults, and because of its slow growth, it may mimic a benign pathology. Clinical symptoms usually include a palpable mass. Imaging is the examination of choice to lead diagnosis. Plain radiographs are usually the first line examination, either showing no lesion or rarely calcifications. Ultrasonography shows a lobulated well-defined mass, that’s hypoechoic, but, because of its non-specificity, MRI is required for better characterization of the lesion. It shows a large lobulated mass (usually >5cm), containing solid tumour, haemorrhage, necrosis and calcifications. Therefore, in T2 weighted sequences, it is heterogeneous, containing areas of intermediate signal, high signal and dark signal. The combination of these 3 shades of signal in the T2 weighted images is called the “triple sign”, and leads to diagnosis. Histological confirmation is necessary. And treatment of choice is the surgical excision of the mass [1-3]. Keywords: Tumour; Soft; Tissue; Sarcoma; Imaging References [1] Al-Ibraheemi A, Ahrens WA, Fritchie K, Dong J, and Oliveira AM, et al. (2019) Malignant tenosynovial giant cell tumor: The true “synovial sarcoma?” A clinicopathologic, immunohistochemical, and molecular cytogenetic study of 10 cases, supporting origin from synoviocytes. Mod Pathol. 32: 242-251. [2] Chambers LA, and Lesher JM (2018) Chronic thigh pain in a young adult diagnosed as synovial sarcoma: A case report. PM&R. 10: 969-973. [3] Mirzaian E, Tavangar SM, Montazeri S, and Yeganeh, FE (2019) Biphasic epithelial predominant synovial sarcoma presenting as painful thigh mass. Iran J Pathol. 14: 261-265

Сравнительный анализ хромосомных аберраций у детей с острым лейкозом

Leukemia is a hematopoetic tissue tumor with a primary lesion of the bone marrow, where the morphological substrate is the blast cell. Chromosomal and molecular genetic aberrations play a major role in the acute leukemia pathogenesis, determing the morphological, immunological and clinical features of the disease. Our study was aimed to to analyze retrospectively the structure and frequency of chromosomal aberrations in children with initially diagnosed acute leukemia. Material and methods. Medical histories retrospective analysis of children charged to oncohematology department of the «Scientific Center of Pediatrics and Pediatric Surgery» in Almaty for the period 2015 - 2017 was carried out. 310 histories with primary diagnosed acute leukemia were studied. Results and discussion. Among 310 patients different chromosome aberrations were isolated in 158 patients (51%) during cytogenetic and molecular cytogenetic (in situ hybridization) studies of bone marrow blast cells. A normal karyotype was observed in 102 patients (33%). Conclusion. The lymphoblastic variant of acute leukemia was determined in 75.5%, that indicates its leading role in AL structure among the children of different ages. AML was determined in 22.6% of all OL cases. The most frequent chromosomal rearrangement in ALL patients was blast cell chromosome hyperdiploidy (10,6%) and t(12;21)(p13;q22)/ETV6-RUNX1,which was detected in 37 (16%) patients. The most frequent AML abberation was t (8;21) (q22;q22)/RUNX1-RUNX1T1, identified in 15 (21.4%) patients. Keywords: acute leukemia, bone marrow, blast cells, karyotype, chromosomal aberrations, cytogenetic study.

Chromosomal Evolution in Aspredinidae (Teleostei, Siluriformes): Insights on Intra- and Interspecific Relationships with Related Groups

The family Aspredinidae comprises a clade of complex systematic relationships, both from molecular and morphological approaches. In this study, conventional and molecular cytogenetic studies coupled with nucleotide sequencing were performed in 6 Aspredininae species (Amaralia hypsiura, Bunocephalus cf. aloikae, Bunocephalus amaurus, Bunocephalus aff. coracoideus, Bunocephalus verrucosus, and Platystacus cotylephorus) from different locations of the Amazon hydrographic basin. Our results showed highly divergent diploid numbers (2n) among the species, ranging from 49 to 74, including the occurrence of an XX/X0 sex chromosome system. A neighbor-joining phylogram based on the cytochrome c oxidase I (COI) showed that Bunocephalus coracoideus is not a monophyletic clade, but closely related to B. verrucosus. The karyotypic data associated with COI suggest an ancestral karyotype for Aspredinidae with a reduced 2n, composed of bi-armed chromosomes and a trend toward chromosomal fissions resulting in higher diploid number karyotypes, mainly composed of acrocentric chromosomes. Evolutionary relationships were discussed under a phylogenetic context with related species from different Siluriformes families. The karyotype features and chromosomal diversity of Aspredinidae show an amazing differentiation, making this family a remarkable model for investigating the evolutionary dynamics in siluriforms as well as in fish as a whole.

Comparative Cytogenetics of Four Sea Turtle Species (Cheloniidae): G-Banding Pattern and in situ Localization of Repetitive DNA Units

Sea turtles are considered flagship species for marine biodiversity conservation and are considered to be at varying risk of extinction globally. Cases of hybridism have been reported in sea turtles, but chromosomal analyses are limited to classical karyotype descriptions and a few molecular cytogenetic studies. In order to compare karyotypes and understand evolutive mechanisms related to chromosome dif­ferentiation in this group, Chelonia mydas, Caretta caretta, Eretmochelys imbricata, and Lepidochelys olivacea were cytogenetically characterized in the present study. When the obtained cytogenetic data were compared with the putative ancestral Cryptodira karyotype, the studied species showed the same diploid number (2n) of 56 chromosomes, with some variations in chromosomal morphology (karyotypic formula) and minor changes in longitudinal band locations. In situ localization using a 18S ribosomal DNA probe indicated a homeologous microchromosome pair bearing a 45S ribosomal DNA locus and size heteromorphism in all 4 species. Interstitial telomeric sites were identified in a microchromosome pair in C. mydas and C. caretta. The data showed that interspecific variations occurred in chromosomal sets among the Cheloniidae species, in addition to other Cryptodira karyotypes. These variations generated lineage-specific karyotypic diversification in sea turtles, which will have considerable implications for hybrid recognition and for the study, the biology, ecology, and evolutionary history of regional and global populations. Furthermore, we demonstrated that some chromosome rearrangements occurred in sea turtle species, which is in conflict with the hypothesis of conserved karyotypes in this group.

A toddler with phylloid-type pigmentary mosaicism and ambiguous genitalia resulting from trisomy 14 induced by a der(Y)t(Y;14)

A 1-year-old baby with phylloid-type pigmentary mosaicism, hypotonia, ambiguous genitalia, and a positive screening test for congenital adrenal hyperplasia was referred. Previous sonograph, cytogenetics, and metabolic profile were inconclusive, therefore we performed an additional karyotype and a molecular cytogenetics studies. A mosaic karyotype 45,X/46,X,der(Y)t(Y;14) was characterized in peripheral blood. Congenital adrenal hyperplasia genes were sequenced and the results were negative. The ambiguous genitalia was the result of the special gonosomal mosaicism. The low level of trisomy 14 led to minor physical characteristics and mild mental retardation; also, Turner syndrome features can be expected rather than severe trisomy 14 stigmata.

Generation of microdissected DNA probes from metaphase chromosomes when chromosome identification by routine staining is impossible.

Application of microdissected DNA libraries and DNA probes in numerous and various modern molecular cytogenetic studies showed them as an efficient and reliable tool in the analysis of chromosome reorganization during karyotypic evolution and in the diagnosis of human chromosome pathology. An important advantage of DNA probe generation by metaphase chromosome microdissection followed by sequence-independent polymerase chain reaction in comparison with the method of DNA probe generation using chromosome sorting is the possibility of DNA probe preparation from chromosomes of an individual sample without cell line establishment for the production of a large number of metaphase chromosomes. One of the main requirements for successful application of this technique is a possibility for identification of the chromosome of interest during its dissection and collection of its material from metaphase plates spread on the coverslip. In the present study, we developed and applied a technique for generation of microdissected DNA probes in the case when chromosome identification during microdissection appeared to be impossible. The technique was used for generation of two sets of Whole Chromosome Paints (WCPs) from all chromosomes of two species of free-living flatworms in the genus Macrostomum, M. mirumnovem and M. cliftonensis. The single-copy chromosome technique including separate collection of all chromosomes from one metaphase plate allowed us to generate WCPs that painted specifically the original chromosome by Chromosome In Situ Suppression Hybridization (CISS-Hybridization). CISS-Hybridization allowed identifying the original chromosome(s) used for DNA probe generation. Pooled WCPs derived from homologous chromosomes increased the intensity and specificity of chromosome painting provided by CISS-Hybridization. In the result, the obtained DNA probes appeared to be good enough for application in our studies devoted to analysis of karyotypic evolution in the genus Macrostomum and for analysis of chromosome rearrangements among the worms of laboratory cultures of M. mirumnovem.

Familial case of microdeletion 22q11.2 syndrome in a second trimester fetus

A case of microdeletion syndrome 22q11.2 in a fetus aborted after prenatal diagnosis is presented. Ultrasound screening at 20+3 weeks of gestation revealed a common arterial trunk, type 1 with the right aortic arch, thymic hypoplasia and so DiGeorge's syndrome was suspected. A cytogenetic study and FISH of a woman's amniotic fluid and blood lymphocytes were performed. In the fetus and mother, the aberration of chromosome 22 is established — microdeletion del(22)(q11.21q11.21). A molecular cytogenetic study of the blood of parents made it possible to establish the inherited nature of the pathology. The diagnosis of the fetus is confirmed by pathomorphological examination.

The Y chromosome disomy syndrome (47, XYY) in children with mental retardation, deviations of sex development and different genome anomalies: molecular cytogenetic studies

The article present the results of retrospectively analyzed children (4424 boys) with mental and psychomotor retardation, congenital malformations and/or developmental micro anomalies. 23 children had various forms of Y chromosome dysomy syndrome. The frequency of this syndrome in the studied cohort was 0.52%; and in this connection the authors discussed the role of Y-chromosome in the origin of mental retardation. Besides, the chromosome instability in sex and somatic cells is supposed to be a common mechanism of different chromosomal anomalies. The authors discussed the possibility of cytogenetic and molecular cytogenetic diagnosis, and also clinical polymorphism of the syndrome. The authors established the necessity of molecular cytogenetic technologies in the diagnosis of different forms of the syndrome, including mosaic forms and isodicentric chromosomes-connected forms. The severity of clinical symptoms doesn’t depend on presence of regular or mosaic forms of the syndrome. The study assumes a possible connection of clinical polymorphism with mosaisism, associated with the presence of abnormal cells (cell lines) in different tissues, together with the role of Y chromosome in the origin of mental retardation in children with Y- chromosome disomy syndrome and other chromosomal anomalies. The authors underline the necessity of molecular cytogenetic diagnosis of different forms of the syndrome for correct medical and genetic consultation.

Геномная и хромосомная патология в головном мозге: причины возникновения и функциональные последствия

Геномная и хромосомная патология может являться механизмом нервных и психических заболеваний. В ходе молекулярно-цитогенетических исследований постмортальных образов клеток центральной нервной системы было показано, что геномная/хромосомная нестабильность и соматический механизм представляют собой элемент патогенного каскада при болезни Альцгеймера, атаксии-телеангиэктазии, аутизме и шизофрении. С помощью цитогеномного анализа и биоинформатических методов были оценены возможные причины и функциональные последствия геномной и хромосомной патологии в клетках головного мозга при этих заболеваниях. Genomic and chromosomal pathology may be a mechanism for neurological and psychiatric diseases. Molecular cytogenetic studies of postmortal samples of the central nervous system have shown that genome/chromosome instability and somatic mosaicism are an element of pathogenic cascade in Alzheimer’s disease, ataxia telangiectasia, autism and schizophrenia. Using cytogenomic analysis and bioinformatics methods possible causes and functional consequences of genomic and chromosomal pathology in the diseased brain have been addressed.

First interchromosomal insertion in a patient with cerebral and spinal cavernous malformations

Autosomal dominant cerebral cavernous malformations (CCM) are leaky vascular lesions that can cause epileptic seizures and stroke-like symptoms. Germline mutations in either CCM1, CCM2 or CCM3 are found in the majority of patients with multiple CCMs or a positive family history. Recently, the first copy number neutral inversion in CCM2 has been identified by whole genome sequencing in an apparently mutation-negative CCM family. We here asked the question whether further structural genomic rearrangements can be detected within NGS gene panel data of unsolved CCM cases. Hybrid capture NGS data of eight index patients without a pathogenic single nucleotide, indel or copy number variant were analyzed using two bioinformatics pipelines. In a 58-year-old male with multiple CCMs in his brain and spinal cord, we identified a 294 kb insertion within the coding sequence of CCM2. Fine mapping of the breakpoints, molecular cytogenetic studies, and multiplex ligation-dependent probe amplification verified that the structural variation was an inverted unbalanced insertion that originated from 1p12-p11.2. As this rearrangement disrupts exon 6 of CCM2 on 7p13, it was classified as pathogenic. Our study demonstrates that efforts to detect structural variations in known disease genes increase the diagnostic sensitivity of genetic analyses for well-defined Mendelian disorders.

Chromosome diversity in species of the genus Arachis, revealed by FISH and CMA/DAPI banding, and inferences about their karyotype differentiation

The species of the genus Arachis (Leguminosae) are ordered into nine sections. The assignment of genome types in this genus has been based on cross-compatibility analysis and molecular cytogenetic studies. The latter has also allowed karyotypically establishing well-defined genomes and reassigning the genome of several species. However, most of these studies have been focused mainly on the sections Arachis and Rhizomatosae. To increase the knowledge about the chromosome diversity of the whole genus, here we performed a detailed karyotype characterization of representative species of most of the sections and genomes of Arachis. This characterization included chromosome morphology, CMA/DAPI chromosome banding, and chromosome marker localization (rDNAloci and one satDNA sequence) by fluorescent in situ hybridization (FISH). Based on the data obtained and other previously published data, we established the karyotype similarities by cluster analysis and defined eleven karyotype groups. The grouping was partly coincident with the traditional genome assignment, except for some groups and some individual species. Karyotype similarities among some genomes were also found. The main characteristics of each karyotype group of Arachis were summarized. Together, our results provide information that may be beneficial for future cytogenetic and evolutionary studies, and also contribute to the identification of interspecific hybrids.

Cytogenetic Studies of <i>Chrysanthemum</i>: A Review

Chrysanthemum is a valuable ornamental plant worldwide, and several of its species are used as herbal tea, medicinal plants, and dietary supplements, among others. Commercial cultivars have been developed through interspecific hybridization and artificial selection to improve the characteristics, production quality, and environmental adaptation for enhancing ornamental value. To better understand the recent research in cytogenetic studies of chrysanthemum, we examined studies concerning polyploidy, karyotyping, banding, fluorescence in situ hybridization (FISH) technique, and inter/intraspecific hybridization. Ploidy level is important in genomic characteristics and has a significant value to horticulturists and plant breeders. Studies have reported that flow cytometry analysis and single-dose molecular markers can be used to determine the chrysanthemum ploidy level. As for karyotyping, a better understanding of karyomorphological relationships and evolution of chrysanthemum and its closely related genera has already been gained. Moreover, karyotype parameters in chrysanthemum studies play a critical role in cultivar identification, classification, and genetic analysis. The FISH technique in chrysanthemum research provides more information on chromosome identification, sequences distribution, and evolution for expediting the development and improvement of plant species. The genomic in situ hybridization (GISH) technique can also be used to test hybridization in chrysanthemum breeding. Hence, this review of molecular cytogenetic studies of chrysanthemum will help us to have a better understanding and knowledge of the taxa breeding and the development and improvement of new cultivars.