Karyotypic Features Research Articles

Assessment of Long-Term Cultivated In Vitro Willow Clones according to Chromosomal Analysis.

Creation and long-term in vitro maintenance of valuable genotype collection is one of the modern approach to conservation of valuable gene pool of woody plants. However, during prolonged cultivation, genetic variability of cells and tissues may accumulate and lead to the loss of valuable characteristics of parental plants. It is therefore important to assess the genetic (including cytogenetic) stability of collection clones. The purpose of this work was to study the karyotype features (number, ploidy level and chromosome size) of various willow clones (S. dasyclados Wimm., S. viminalis L., S. purpurea L., S. caspica Pall., х S. palustrisHost.) under conditions of long-term in vitro storage. No such research has been conducted on willow so far. Nevertheless, there is evidence of significant influence of ploidy level on growth, productivity, and composition of wood for willow plants. Our study was based on the plants of five micropropagated willow clones rated as promising for plantation forestry. The plants used in the study were maintained in vitro for a long period (14 years) by rare subculturing (once in 5 months) on a hormone-free1/2 WPM nutrient medium under standard cultivation conditions (25± 2°C, 16 h light/8 h dark, 2.0 klx). Throughout the entire in vitro cultivation period, the plants showed proper growth and development, high regeneration activity, and no visible signs of somaclonal variation. Willow is one of the rather difficult objects for karyotype analysis. The authors improved the method of preparation and analysis of specimens. During the long-term cultivation, the clones showed cytogenetic stability, maintaining the ploidy (2n = 2х = 38 or 2n= 4х = 76) and the mixoploid nature of the original plants. Data obtained gives an update on the sizes of chromosomes of clones with different ploidy. The absolute chromosome length for diploid clones varies from 0.8 to 2.1 μm; tetraploid, from 0.9 to 2.5 μm. There were no statistically significant differences in the average chromosome length between diploid and tetraploid clones. All studied willow clones during long-term (for 14years) in vitro cultivation on a hormone-free nutrient media retain the karyotype of the respective species.

Oligo-FISH barcode chromosome identification system provides novel insights into the natural chromosome aberrations propensity in the autotetraploid cultivated alfalfa.

Alfalfa is one of the most economically valuable forage crops in the world. However, molecular cytogenetic studies in alfalfa lag far behind other cash crops and have reached a bottleneck. Here, we developed a novel chromosome identification system by designing 21 oligo probes in specific regions of each chromosome, which can be used as a barcode to simultaneously distinguish all chromosomes in a cell. Using this system, we revealed the chromosome karyotype features and evolutionary differences among 10 cultivated alfalfa varieties. Interestingly, we also found two chromosomal variation types, i.e. aneuploidy and large chromosomal segment deletions in the seeds of three alfalfa varieties. Variation frequency analysis showed that only 7/173 seeds in those three alfalfa varieties had chromosome aberrations, which indicated that the inheritance and meiosis of alfalfa had evolved to a relatively stable state. Remarkably, 4/7 variation seeds were chromosome 2 aberrations, suggesting that chromosome 2 appears to be more susceptible to natural chromosomal aberrations than other chromosomes during inheritance. DNA sequence variation analysis showed that the difference of presence and absence variations (PAVs) among homologous copies of chromosome 2 was larger than that of the other seven chromosomes. We suggest that such large PAV divergence among homologous copies may provide the physical basis for natural chromosome 2 aberrations propensity. Our study provides a valuable and efficient tool for alfalfa's molecular cytogenetics and sheds new insights into the propensity for natural chromosome aberrations during autopolyploid inheritance.

Karyotype analysis and chromosomal characterization of hibiscus cannabinus l.

Seven germplasm of Hibiscus cannabinus L. (Acc. No. 95, 4652, 4654, 4655, 4656, 4657, and 4810) were investigated for their karyotype analysis and chromosomal characterization. These germplasm of H. cannabinus were found to possess 2n = 36 chromosomes. Symmetric nature of karyotype was observed in Acc. No. 4654. In contrast, metacentric and submetacentric chromosomes were present in other six accessions revealing the asymmetric nature of karyotype. Based on karyotypic features Acc. No. 4654 was considered relatively primitive and Acc. No. 4652 was relatively advanced among the seven germplasm. Moreover, karyomorphological study proved their divergence in relation to different morphological feature of the chromosomes. Bangladesh J. Bot. 53(4): 967-971, 2024 (December)

What is the True Karyotype of <i>Bufotes latastii</i> (Amphibia, Anura, Bufonidae)?

The karyotype is one of the most important characteristics of an animal species and can be very useful for identifying taxa. The chromosome sets of the West Himalayan endemic Ladakh toad, Bufotes latastii, were previously described in several papers, but differed greatly from each other. To deal with these contradictions, we re-examined the karyotype of B. latastii from India and compared it with the sets of chromosomes of the most morphologically similar toad species inhabiting East Asia. It turned out that the diploid set of B. latastii consists of 22 chromosomes (2n = 22; NF = 44), of which six pairs are large and five are small. As a rule, the 4th, 5th, and 7th pairs of chromosomes are submetacentric and all the others are metacentric. The chromosomal formula is 2n = 16 m + + 6 sm = 22. The nucleolar organizers (NOR) in B. latastii are located on the long arms of submetacentric chromosomes of the 5th pair, which greatly distinguishes this species from most diploid species of the genus Bufotes. Karyotypes of two other studied species (Duttaphrynus stomaticus and Strauchbufo raddei), which can be morphologically similar to B. latastii, also consist of 22 chromosomes (2n = 22; NF = 44) of which six pairs are large and five are small, but there is only a pair of submetacentric chromosomes (2n = 20 m + 2 sm = 22). The most notable differences between these three species were in the position of NORs. In B. latastii they were located in the telomeric region of the long arm of the 5th pair, in D. stomaticus in the submedial region of the short arm of the 7th pair, and in S. raddei in the telomeric region of the short arm of the 4th pair. Discriminant analyses of the relative length of chromosomes and centromeric indices also revealed significant differences between the karyotypes of these three species. Our study made it possible to clearly distinguish B. latastii from D. stomaticus and S. raddei by karyotype characteristics. This may be important if it is necessary to identify East Asian morphologically similar toad species.

Comparative karyological features of several populations of Populus euphratica Oliv., grown under different environmental conditions in Iran

Abstract Understanding genetic structure and chromosomal characteristics is essential for developing effective breeding programmes and improving plant species. This research compared karyotypic features of 10 plant populations of Populus euphratica from various regions of Iran. Fresh roots grown from cuttings of the populations were used to get metaphase cells. Then several chromosomal parameters were recorded and analysed using a nested statistical model. All the studied populations were diploid, with 2n = 38 chromosomes, consisting of medium and sub-medium chromosome types. Significant differences (P ⩽ 0.01) were observed between the plant populations in chromosomal dimensions and arm ratios, suggesting chromosomal rearrangements. Chromosome lengths in the studied populations ranged from 0.69 to 3.38 μm. Intra-chromosomal index (A1) showed clear asymmetrical differences between the plant populations. Furthermore, using Stebbins's standards, the studied populations classified as 1A and 1B classes, demonstrated more asymmetry than those categorized as 1B and 2B, respectively. Cytological differences between the plant populations, collected from different parts of the country, showed that chromosome structural rearrangements are responsible for the speciation and adaption of the species against the mentioned variable ecological conditions and play a key role in response to diverse climatic and geographical conditions.

Chromosomal mapping of 5S rDNA in two species of the genus Acanthocephalus (Echinorhynchida)

Chromosomal mapping of 5S rDNA in two Acanthocephala species was performed for the first time using fluorescence in situ hybridization (FISH) with a 5S rDNA probe. The 5S rDNA PCR products from the genomes of both species were sequenced and aligned and an identical 141 bp long coding region was determined. The same patterns of 5S rDNA gene cluster distribution were observed, with FISH signal restricted to a single autosomal chromosome pair. A preference for distal positioning on the chromosomes (subtelomeric position) was observed in both species. In addition, two-color FISH was performed to examine the mutual positions of 5S and 18S rDNA on the chromosomes. Our knowledge of the organization of the Acanthocephala genome is extremely limited and its chromosomes are poorly studied. Any new information about the location of chromosomal markers as important features of the respective karyotype may be useful in solving evolutionary questions.

Comparative Characteristics of Abnormal Karyotypes in Secondary Acute Leukemia

Comparative Characteristics of Abnormal Karyotypes in Secondary Acute Leukemia

Plasticity of the mitotic spindle in response to karyotype variation

Karyotypes, composed of chromosomes, must be accurately partitioned by the mitotic spindle for optimal cell health. However, it is unknown how underlying characteristics of karyotypes, such as chromosome number and size, govern the scaling of the mitotic spindle to ensure accurate chromosome segregation and cell proliferation. We utilize budding yeast strains engineered with fewer chromosomes, including just two "mega chromosomes," to study how spindle size and function are responsive to, and scaled by, karyotype. We determined that deletion and overexpression of spindle-related genes are detrimental to the growth of strains with two chromosomes, suggesting that mega chromosomes exert altered demands on the spindle. Using confocal microscopy, we demonstrate that cells with fewer but longer chromosomes have smaller spindle pole bodies, fewer microtubules, and longer spindles. Moreover, using electron tomography and confocal imaging, we observe elongated, bent anaphase spindles with fewer core microtubules in strains with mega chromosomes. Cells harboring mega chromosomes grow more slowly, are delayed in mitosis, and a subset struggle to complete chromosome segregation. We propose that the karyotype of the cell dictates the microtubule number, type, spindle pole body size, and spindle length, subsequently influencing the dynamics of mitosis, such as the rate of spindle elongation and the velocity of pole separation. Taken together, our results suggest that mitotic spindles are highly plastic ultrastructures that can accommodate and adjust to a variety of karyotypes, even within a species.

Cryptic Taxa Revealed through Combined Analysis of Chromosomes and DNA Barcodes: The Polyommatus ripartii Species Complex in Armenia and NW Iran.

The detection of cryptic species in complexes that have undergone recent speciation is often difficult, since many standard nuclear markers have not yet accumulated differences between closely related taxa, and differences in mitochondrial markers can be leveled out due to mitochondrial introgressions. In these cases, the use of derived chromosomal characters such as non-ancestral chromosomal numbers and/or unusual karyotype features may be a solution to the species delimitation problem. However, non-ancestral but similar karyotypes may arise secondarily as a result of homoplastic evolution, and their interpretation as homologies may lead to incorrect taxonomic conclusions. In our study, we show that the combined use of mitochondrial DNA barcodes and karyotypes helps to solve this problem and identifies cryptic species in situations where each of these markers does not work individually. Using this approach, we show that the fauna of Armenia and adjacent Iran includes the following cryptic taxa of the Polyommatus ripartii species complex (haploid chromosome number, n in parentheses): P. ripartii paralcestis (n = 90), P. ripartii kalashiani, subsp. nov (n close to 90), P. emmeli, sp. nov. (n = 77-79), P. keleybaricus, sp. nov. (n = 86), P. demavendi belovi (n = 73-75), P. demavendi antonius, subsp. nov. (n = 71-73), P. admetus anatoliensis (n = 79) and P. eriwanensis (n = 29-34). Polyommatus admetus yeranyani is synonymized with P. admetus anatoliensis.

Karyotype depends on sperm head morphology in some amniote groups.

The karyotype of an organism is the set of gross features that characterize the way the genome is packaged into separate chromosomes. It has been known for decades that different taxonomic groups often have distinct karyotypic features, but whether selective forces act to maintain these differences over evolutionary timescales is an open question. In this paper we analyze a database of karyotype features and sperm head morphology in 103 mammal species with spatulate sperm heads and 90 sauropsid species (birds and non-avian reptiles) with vermiform heads. We find that mammal species with a larger head area have more chromosomes, while sauropsid species with longer heads have a wider range of chromosome lengths. These results remain significant after controlling for genome size, so sperm head morphology is the relevant variable. This suggest that post-copulatory sexual selection, by acting on sperm head shape, can influence genome architecture.

A new Senecio (Asteraceae) from the Anjaneri Hills of Nashik, India

A new species of Senecio (Asteraceae, Senecioneae), Senecio anjanericus is described and illustrated from the Anjaneri Hills of Nashik district, Maharashtra, India, based on morphological and cytogenetical studies. The species resembles Senecio bombayensis, but differs from it in small size of the ligules, presence of conspicuous foliose supplementary bracts and dense indumentum on stem. The somatic chromosome number was observed to be 2n = 2x = 20, with all the chromosomes exhibiting median region centromeres. A detailed morphological description, illustration and karyotypic features of the new species are provided.

Karyotipe analysis of the tiger barb (Puntigrus tetrazona bleeker, 1855) of North Sumatra

The Tiger barb, Puntigrus tetrazona, is an ornamental fish native to Indonesia with a notably striking visual. The research was conducted to perform a karyotype analysis of the Tiger barb chromosomes, including the numbers, sizes, and shapes. The study employed a descriptive approach, by applying 0.007% colchicine for 12 hours. Chromosome preparation was carried out using solid tissue technique, and staining was performed with 5% Giemsa stain. Data analysis was performed using IdeoKar 1.3 software, and the karyotype of the chromosomes was constructed using Adobe Photoshop CS 3. The results of the study showed that the tiger barb had the number of chromosome haploid were 50 with sizes ranging from 1.16 µm to 5.35 µm. The largest value of r was 0.93 and the largest chromosome had a relative length percentage of 5.57. The chromosome shape percentage was 2.54. The highest centromere index obtained 0.47. Furthermore, the study found a TF% value was 40.48%, an Ask% value was 59.51%, an XCI value was 0.38, and an HCL value was 90.08. This research provides an understanding of the karyotype characterization of the tiger barb and an insight for further research in the genetics study of fish.

Chromosome numbers of some native Iranian plants

Chromosome numbers of 11 native species from five families (Apiaceae, Asteraceae, Brassicaceae, Lamiaceae, and Fabaceae) of Iran were investigated. Most of them are endemic or subendemic species. This study aimed to determine chromosome number and provide general information on karyotype characteristics of selected native species of Iran. For Achillea kellalensis (2n = 18), Noccidium hastulatum (2n = 14), Phlomoides glabra (2n = 22), Astragalus gompholobium (2n = 16), Astragalus urbanus (2n = 16), Astragalus askius (2n = 16), Oxytropis iranica (2n = 16), chromosome numbers are reported for the first time, for Prangos uloptera (2n = 44) for the first time based on material from Iran.

Repetitive DNAs and chromosome evolution in Megaleporinus obtusidens and M. reinhardti (Characiformes: Anostomidae).

The high dynamism of repetitive DNAs is a major driver of chromosome evolution. In particular, the accumulation of repetitive DNA sequences has been reported as part of the differentiation of sex-specific chromosomes. In turn, the fish species of the genus Megaleporinus are a monophyletic clade in which the presence of differentiated ZZ/ZW sex chromosomes represents a synapomorphic condition, thus serving as a suitable model to evaluate the dynamic evolution of repetitive DNA classes. Therefore, transposable elements (TEs) and in tandem repeats were isolated and located on chromosomes of Megaleporinus obtusidens and M. reinhardti to infer their role in chromosome differentiation with emphasis on sex chromosome systems. Despite the conserved karyotype features of both species, the location of repetitive sequences - Rex 1, Rex 3, (TTAGGG)n, (GATA)n, (GA)n, (CA)n, and (A)n - varied both intra and interspecifically, being mainly accumulated in Z and W chromosomes. The physical mapping of repetitive sequences confirmed the remarkable dynamics of repetitive DNA classes on sex chromosomes that might have promoted chromosome diversification and reproductive isolation in Megaleporinus species.

Comparison of haracteristics of the karyotype and meiosis of cryptic forms of the viviparous lizard Zootoca vivipara and species of the closely related genus Takydromus (Squamata: Lacertidae)

Characteristics of the karyotype and early meiosis of two males of the cryptic “western” form of the viviparous lizard (Zootoca vivipara Lichtenstein, 1823) (genus Zootoca Wagler, 1830) with multiple sex chromosomes (female Z1Z2W/Z1Z1Z2Z2 male) were examined. The data obtained were compared with 1) those of the males of the same cryptic form from other locality, with 2) those of the males of other cryptic form also possessing the multiple sex chromosomes and with 3) those of the species of closely related genus Takydromus Daudin, 1802 with simple sex chromosomes, ZW/ZZ. Multiple sex chromosomes may influence meiosis and play a role in isolation. The males of cryptic western form of Z. vivipara studied revealed the karyotype with 36 acrocentric chromosomes (2n=36A). In early meiosis the spreading of synaptonemal complexes (SC) of the bivalents of these males were obtained and analyzed. Eighteen SC were observed, including SC of the Z1Z1 (pair 6) sex chromosomes. Characteristics of SC are compared with the number and the shape of bivalents and chromosomes at the diakinesis and metaphase 11 stages of the meiosis of the males from other population and with those in the other cryptic Russian form of the species. Comparative analysis of two cryptic forms has demonstrated some differences in the morphology of SC Z1Z1 sex chromosomes at the early stages of prophase 1 of meiosis (the late zygotena – the middle pachytene stages). However both the SC of sex chromosomes and SC of all remained chromosomes were fully synapted. All 18 bivalents were regular segregated forming haploid spermatocyte II with18 chromosomes, including two sex chromosomes (n=8, Z1Z2) Thus characteristics of karyotype and early meiosis of the males of western form belonging to different localities are fully coincident with those of Russian cryptic forms of Z. vivipara with multiple sex chromosomes as well. However, these features were differed from those for the species of the closely related genus Takydromus with simple sex chromosome system (ZW) where some disturbances in the course of mitoses and meiosis were observed. The results are in agreement with those suggested previously about the genomic factor(s) stabilizing the meiosis and the maintenance of multiple sex chromosome in the different cryptic forms of complex Z. vivipara.

Karyotype characterization of endosperm-derived plants of Passiflora cristalina Vanderplank and Zappi, a wild amazonian passionfruit species

Karyotype characterization of endosperm-derived plants of Passiflora cristalina Vanderplank and Zappi, a wild amazonian passionfruit species

Chromosome counts and karyotype features of different ecotypes of Allium L. species (Amaryllidaceae – Subg. Melanocrommyum) in Iran

This study aimed to investigate the karyotypes of five Allium species, which belong to three sections of the subgenus Melanocrommyum. Bulbs from these species were collected from natural habitats in Iran, and their somatic chromosomes were analysed. The results revealed that all examined members of subg. Melanocrommyum had a basic chromosome number of x=8 and were diploid (2n=2x=16). Chromosomal data for A. saralicum and A. shatakiense are reported here for the first time. The karyotypes exhibited a variety of chromosome types and sizes, including variations observed among different accessions of the same species. In particular, A. saralicum showed satellite chromosomes ranging in size from 2.2 to 3.71 µm, located on the short arm. Seven accessions of A. saralicum, A. stipitatum, and A. haemanthoides demonstrated the presence of 1-3 B chromosomes with centromeres located in the median or subterminal position. Notably, the number of B chromosomes varied even among different accessions of the same species. Based on various indices, the karyotypes of the species were classified into symmetric and asymmetric groups. All karyotype asymmetry methods consistently identified A. stipitatum as the species with the most asymmetric chromosomes, while A. ubipetrense was recognized as the most symmetric species. This study contributes to the karyological knowledge of the genus Allium and provides valuable data for future taxonomic research. It emphasizes the significance of chromosomal characteristics in understanding plant evolution and species diversity within the Allium genus.

Repetitive DNA Mapping in Five Genera of Tree Frogs (Amphibia: Anura) from the Atlantic Forest: New Highlights on Genomic Organization in Hylidae

Introduction: The tribes Cophomantini, Scinaxini, and Dendropsophini are anurans that belong to Hylidae, with wide distribution in tropical and subtropical regions around the world. The taxonomy and systematics of this family remain in a state of ongoing revision. Previous cytogenetic analyses of genera Boana, Bokermannohyla, Ololygon, Scinax, and Dendropsophus described some karyotypic characters such as conventional staining, C-banding and NORs, and FISH with specific probes. Methods: This study describes for the first time the karyotypes of four species: Bokermannohyla ibitipoca, Ololygon luizotavioi, Dendropsophus bipunctatus, and Dendropsophus ruschii. Furthermore, we map CA(15) and CAT(10) microsatellite sites for the aforementioned species and six more species from the same genera for insight into the chromosomal evolution within the subfamily Hyalinae. Results: B. ibitipoca and O. luizotavioi had 2n = 24 and karyotypic formulas 18m + 4sm + 2st and 8m + 12sm + 4st, while D. bipunctatus and D. ruschii showed 2n = 30 and karyotypic formulas 12m + 12sm + 4st + 2t and 10m + 10sm + 6st + 4t, respectively. The diploid numbers and karyotypic formulas revealed here follow the previously reported trend for Hylidae, except B. ibitipoca has a particularity of eight metacentric chromosomes, more than what is commonly found in species of this genus. The microsatellites probes CA(15) and CAT(10) had markings accumulated in blocks in the centromeric, pericentromeric, and terminal regions that were more specific for some species, as well as markings scattered along the chromosomes. We present a comprehensive review table of current data on cytogenetics of these genera. Conclusion: Our findings showed that the karyotypes of the hylids studied here majority fit the postulated conserved diploid number (2n = 24) and morphological chromosome patterns, while the mapping of the microsatellites enabled us to detect differences between species that share similar chromosomal morphologies.

Chromosomal rearrangements played an important role in the speciation of rice rats of genus Cerradomys (Rodentia, Sigmodontinae, Oryzomyini)

Rodents of the genus Cerradomys belong to tribe Oryzomyini, one of the most diverse and speciose groups in Sigmodontinae (Rodentia, Cricetidae). The speciation process in Cerradomys is associated with chromosomal rearrangements and biogeographic dynamics in South America during the Pleistocene era. As the morphological, molecular and karyotypic aspects of Myomorpha rodents do not evolve at the same rate, we strategically employed karyotypic characters for the construction of chromosomal phylogeny to investigate whether phylogenetic relationships using chromosomal data corroborate the radiation of Cerradomys taxa recovered by molecular phylogeny. Comparative chromosome painting using Hylaeamys megacephalus (HME) whole chromosome probes in C. langguthi (CLA), Cerradomys scotii (CSC), C. subflavus (CSU) and C. vivoi (CVI) shows that karyotypic variability is due to 16 fusion events, 2 fission events, 10 pericentric inversions and 1 centromeric repositioning, plus amplification of constitutive heterochromatin in the short arms of the X chromosomes of CSC and CLA. The chromosomal phylogeny obtained by Maximum Parsimony analysis retrieved Cerradomys as a monophyletic group with 97% support (bootstrap), with CSC as the sister to the other species, followed by a ramification into two clades (69% of branch support), the first comprising CLA and the other branch including CVI and CSU. We integrated the chromosome painting analysis of Eumuroida rodents investigated by HME and Mus musculus (MMU) probes and identified several syntenic blocks shared among representatives of Cricetidae and Muridae. The Cerradomys genus underwent an extensive karyotypic evolutionary process, with multiple rearrangements that shaped extant karyotypes. The chromosomal phylogeny corroborates the phylogenetic relationships proposed by molecular analysis and indicates that karyotypic diversity is associated with species radiation. Three syntenic blocks were identified as part of the ancestral Eumuroida karyotype (AEK): MMU 7/19 (AEK 1), MMU 14 (AEK 10) and MMU 12 (AEK 11). Besides, MMU 5/10 (HME 18/2/24) and MMU 8/13 (HME 22/5/11) should be considered as signatures for Cricetidae, while MMU 5/9/14, 5/7/19, 5 and 8/17 for Sigmodontinae.

Tracking Karyotype Changes in Treatment-Induced Drug-Resistant Evolution.

Karyotype coding, which encompasses the complete chromosome sets and their topological genomic relationships within a given species, encodes system-level information that organizes and preserves genes' function, and determines the macroevolution of cancer. This new recognition emphasizes the crucial role of karyotype characterization in cancer research. To advance this cancer cytogenetic/cytogenomic concept and its platforms, this study outlines protocols for monitoring the karyotype landscape during treatment-induced rapid drug resistance in cancer. It emphasizes four key perspectives: combinational analyses of phenotype and karyotype, a focus on the entire evolutionary process through longitudinal analysis, a comparison of whole landscape dynamics by including various types of NCCAs (including genome chaos), and the use of the same process to prioritize different genomic scales. This protocol holds promise for studying numerous evolutionary aspects of cancers, and it further enhances the power of karyotype analysis in cancer research.