Mitotic Karyotype Research Articles

EVALUATION OF CALCIUM CARBIDE'S CYTOTOXIC EFFECTS ON ONION (Allium cepa)

The purpose of this investigation was to see if Calcium Carbide (CaC2) had any harmful effects on onions (Allium cepa L.). Allium cepa root tips were grown in various concentrations of Calcium Carbide (CaC2) (0.25g, 0.50g, 0.75g, and 1.00g)/ 250ml, with distilled water serving as a control. For cytological tests, the root tips of Allium cepa growing in the treatments and control were removed daily between 7:30am and 8:30am. Pretreatment, fixation, hydrolysis, squashing, and staining of cells for mitotic investigations were performed, and data on cytological parameters were collected using a light microscope at a magnification of X40. The mitotic index (MI) and karyotype analysis were used to assess the data collected on these parameters. The results of this study showed that root tips treated with 0.25g of Calcium Carbide (CaC2) have a mitotic index of 45.83 and the rate of cell division decreases with an increase in the concentration of Calcium Carbide (CaC2) as the cell divides the mitotic index dropped sharply. These finding indicated that Calcium Carbide is a strong mitotic inhibitor and could give rise to mitotic abnormalities with increase in concentration and also reduced cell division. We therefore recommended that there is need for further investigation using lower concentrations of Calcium Carbide as well as other mutagenic substances in order to ascertain their effect on the chromosomal behavior.

A comparative analysis of the chromosomes of three FARQ species complex members, Ceratitis rosa, C. quilicii, and C. fasciventris F2 (Diptera: Tephritidae).

The Ceratitis FARQ species complex consists of four highly destructive agricultural pests of Africa, namely C. fasciventris, C. anonae, C. rosa, and C. quilicii. The members of the complex are considered very closely related and the species limits among them are rather obscure. Their economic significance and the need for developing biological methods for their control makes species identification within the complex an important issue, which has become clear that can only be addressed by multidisciplinary approaches. Chromosomes, both mitotic and polytene, can provide a useful tool for species characterization and phylogenetic inference among closely related dipteran species. In the current study, we present the mitotic karyotype and the polytene chromosomes of C. rosa and C. quilicii together with in situ hybridization data. We performed a comparative cytogenetic analysis among the above two species and C. fasciventris, the only other cytogenetically studied member of the FARQ complex, by comparing the mitotic complement and the banding pattern of the polytene chromosomes of each species to the others, as well as by studying the polytene chromosomes of hybrids between them. Our analysis revealed no detectable chromosomal rearrangements discriminating the three FARQ members studied, confirming their close phylogenetic relationships.

Comparative Karyotype Analysis of Parasitoid Hymenoptera (Insecta): Major Approaches, Techniques, and Results.

A comprehensive review of main approaches, techniques and results of the chromosome study of parasitic wasps is given. In this group, the haploid chromosome number ranges from n = 3 to 23. Distribution of parasitic wasp species by the chromosome number is bimodal, with two obvious modes at n = 6 and 11. Karyotype analysis based on routinely stained preparations of mitotic chromosomes can be used to identify members of taxonomically complicated parasitoid taxa and to distinguish between them. Morphometric study effectively reveals subtle differences between similar chromosome sets of parasitic wasps. If combined with meiotic analysis and/or cytometric data, information on mitotic karyotypes can highlight pathways of the genome evolution in certain parasitoid taxa. C- and AgNOR-banding as well as staining with base-specific fluorochromes detected important interspecific differences within several groups of parasitic wasps. Fluorescence in situ hybridization (FISH) is successfully used for physical mapping of various DNA sequences on parasitoid chromosomes. These techniques demonstrate that heterochromatic segments are usually restricted to pericentromeric regions of chromosomes of parasitic wasps. Haploid karyotypes carrying one or two nucleolus organizing regions (NORs) are the most frequent among parasitoid Hymenoptera. In combination with chromosome microdissection, FISH could become a powerful tool exploring the genome evolution of parasitic wasps. Perspectives of the comparative cytogenetic study of parasitoid Hymenoptera are outlined.

Identification of differentially methylated genes in first-trimester placentas with trisomy 16

The presence of an extra chromosome in the embryo karyotype often dramatically affects the fate of pregnancy. Trisomy 16 is the most common aneuploidy in first-trimester miscarriages. The present study identified changes in DNA methylation in chorionic villi of miscarriages with trisomy 16. Ninety-seven differentially methylated sites in 91 genes were identified (false discovery rate (FDR) < 0.05 and Δβ > 0.15) using DNA methylation arrays. Most of the differentially methylated genes encoded secreted proteins, signaling peptides, and receptors with disulfide bonds. Subsequent analysis using targeted bisulfite massive parallel sequencing showed hypermethylation of the promoters of specific genes in miscarriages with trisomy 16 but not miscarriages with other aneuploidies. Some of the genes were responsible for the development of the placenta and embryo (GATA3-AS1, TRPV6, SCL13A4, and CALCB) and the formation of the mitotic spindle (ANKRD53). Hypermethylation of GATA3-AS1 was associated with reduced expression of GATA3 protein in chorionic villi of miscarriages with trisomy 16. Aberrant hypermethylation of genes may lead to a decrease in expression, impaired trophoblast differentiation and invasion, mitotic disorders, chromosomal mosaicism and karyotype self-correction via trisomy rescue mechanisms.

Characterization of axolotl lampbrush chromosomes by fluorescence in situ hybridization and immunostaining

The lampbrush chromosomes (LBCs) in oocytes of the Mexican axolotl (Ambystoma mexicanum) were identified some time ago by their relative lengths and predicted centromeres, but they have never been associated completely with the mitotic karyotype, linkage maps or genome assembly. We identified 9 of the axolotl LBCs using RNAseq to identify actively transcribed genes and 13 BAC (bacterial artificial clone) probes containing pieces of active genes. Using read coverage analysis to find candidate centromere sequences, we developed a centromere probe that localizes to all 14 centromeres. Measurements of relative LBC arm lengths and polymerase III localization patterns enabled us to identify all LBCs. This study presents a relatively simple and reliable way to identify each axolotl LBC cytologically and to anchor chromosome-length sequences (from the axolotl genome assembly) to the physical LBCs by immunostaining and fluorescence in situ hybridization. Our data will facilitate a more detailed transcription analysis of individual LBC loops.

The chromosomes of Drosophila suzukii (Diptera: Drosophilidae): detailed photographic polytene chromosomal maps and in situ hybridization data

The spotted wing drosophila, D. suzukii, is a serious agricultural pest attacking a variety of soft fruits and vegetables. Although originating from East Asia it has recently invaded America and Europe raising major concern about its expansion potential and the consequent economic losses. Since cytogenetic information on the species is scarce, we report here the mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of D. suzukii. The mitotic metaphase complement contains three pairs of autosomes, one of which is dot-like, and one pair of heteromorphic (XX/XY) sex chromosomes. The salivary gland polytene complement consists of five long polytene arms, representing the two metacentric autosomes and the acrocentric X chromosome, and one very short polytene element, which corresponds to the dot-like autosome. Banding pattern as well as the most characteristic features and prominent landmarks of each polytene chromosome arm are presented and discussed. Furthermore, twelve gene markers have been mapped on the polytene chromosomes of D. suzukii by in situ hybridization. Their distribution pattern was found quite similar to that of D. melanogaster revealing conservation of synteny although the relative position within each chromosome arm for most of the genes differed significantly between D. suzukii and D. melanogaster. The chromosome information presented here is suitable for comparative cytogenetic studies and phylogenetic exploration, while it could also facilitate the assembly of the genome sequence and support the development of genetic tools for species-specific and environment-friendly biological control applications such as the sterile insect technique.

Ongoing chromosomal instability and karyotype evolution in human colorectal cancer organoids.

Chromosome segregation errors cause aneuploidy and genomic heterogeneity, which are hallmarks of cancer in humans. A persistent high frequency of these errors (chromosomal instability (CIN)) is predicted to profoundly impact tumor evolution and therapy response. It is unknown, however, how prevalent CIN is in human tumors. Using three-dimensional live-cell imaging of patient-derived tumor organoids (tumor PDOs), we show that CIN is widespread in colorectal carcinomas regardless of background genetic alterations, including microsatellite instability. Cell-fate tracking showed that, although mitotic errors are frequently followed by cell death, some tumor PDOs are largely insensitive to mitotic errors. Single-cell karyotype sequencing confirmed heterogeneity of copy number alterations in tumor PDOs and showed that monoclonal lines evolved novel karyotypes over time in vitro. We conclude that ongoing CIN is common in colorectal cancer organoids, and propose that CIN levels and the tolerance for mitotic errors shape aneuploidy landscapes and karyotype heterogeneity.

Analysis of karyotype, chromosome characteristics, variation in mucilage content and grain yield traits in Plantago ovata and P. psyllium species

Plantago ovata and P. psyllium are of the most abundant and widely distributed Plantago species in the world. World-wide, it is an important and growing industrial and medicinal crop for dry land agriculture. In spite of this, basic characterization for economically important traits of these species is lacking for many accessions. In particular, there are gaps in our knowledge about accession identity and ploidy levels and the effects of agronomic practices of yield. This study is aimed at determining mitotic chromosome number, karyotype characteristics, morphological and mucilage character variation of wild accessions of Plantago species collected from a wide geographic range in Iran. Chromosome numbers were determined by a modification of conventional root tip squash method and karyotypes were digitally analysed. Morphological characters were evaluated under experimental field condition. Three replications of morphological and mucilage characters were also measured in the wild in situ natural habitats. The analysis of the karyotype indices showed that all P. ovata accessions were diploid (2n = 8) with small, homogeneous chromosomes. Likewise, P. psyllium accessions were diploid (2n = 12) and had symmetrical karyotype demonstrating P. psyllium as a primitive species. Results showed significant differences in accessions and environments with respect to seed yield, thousand grain weight, mucilage yield, mucilage content, days to flowering and plant height. P. ovata accumulated higher mucilage than P. psyllium. Mucilage content was higher in samples collected from natural habitats compared with those grown under experimental field conditions whereas mucilage yield was lower under field evaluation in natural habitats. Genotype by environment analysis revealed that the most stable accessions were G2 (P. ovata) and G6, G7 and G8 (P. psyllium) for seed yield, and G2 and G4 (P. ovata) and G8 (P. psyllium) for mucilage content, G4 (P. ovata) and all P. psyllium for grain weight. All accessions tested showed stability for mucilage yield, flowering stalk height and days to flowering. The outcome of karyotype analysis and field evaluations in this study provides information important to Plantago breeders focused on crop improvement.

An idiogram on pachytene bivajents with high resalution multiple bands of Epinephelus malabaricus

Epinephelus malabaricus (Perciformes, Serranidae), a rare marine commercial fish inhabits in the warm-water reef along the southeast coast of China. In the present study, well-spread pachytene bivalents with multiple high-resolution bands were obtained after the testes were treated with a hypotonic alkaline solution and a high-chloroform fixative solution, showing that the number and characteristics of band in each bivalent were stable. According to karyotype analysis, the haploid chromosome set was n=24 (24t), and no heteromorphic bivalent was found. The relative length of the longest and shortest bivalent were 5.86 and 1.66, and the length ratio was 3.53, which was much higher than the length ratio of the exact metaphase mitotic karyotype (1.5) and premetaphase endonuclease karyotype (1.75). An idiogram with 447 bands was constructed, and the zone of each bivalent was divided, respectively. The detailed description of the landmark system and the band positions were preliminary given. This study aims to provide a theoretical reference for the further research on cytogenetics and the physical map construction of chromosome fine frame of E. malabaricus.

Karyotype analysis of Common Cocklebur (Xanthium strumarium L.)

Objective: The purpose of this study is to determine the mitotic chromosome number, morphometric parameters, and karyotypes of Xanthium strumarium and make contributions to other multidisciplinary studies on the genus. Material and Methods: The seeds were germinated on moist filter paper in Petri dishes at 25°C. Actively growing root tips were pre-treated with aqueous paradichlorobenzene for 4h at room temperature. Then, the root tips were fixed with acetic alcohol (1:3 glacial acetic acid–absolute ethanol) for at least 24 h at 4°C, hydrolysed in 1 N HCl at 60°C for 3 min, then rinsed in tap water for 3–5 min. Finally, they were stained in Feulgen for 1 h and mounted in 45% acetic acid. Digital microphotographs from at least five well-spread metaphase plates were taken using an Olympus BX51 microscope and were recorded with an Olympus Camedia C-4000 digital camera. Results: The chromosome number is determined as 2n = 36 for this taxon. The karyotype consists of 16 median region (m) and 2 submedian region (sm) chromosomes. The metaphase chromosome length ranges from 2.30 to 4.03 μm, longest to shortest chromosome ratio is 1.7:1.1, total karyotype length (TKL) 54.76 mm and the karyotype symmetry is type 1A. Conclusion: The results of this study showed that the chromosome number of Xanthium strumarium is 2n=36. Satellites were not observed in the karyotype of this species.Identifying the chromosome number of this species in this study provides a base for biosystematic studies.

A review of more than 30 years of cytogenetic studies of Tephritidae in support of sterile insect technique and global trade

AbstractCytogenetics of Tephritidae has contributed for more than 30 years to the efficient control of pest members of this family and the species delimitation among them. The sterile insect technique (SIT) is a species‐specific and environmentally friendly method for the population control of insect pest species, always as a component of integrated pest management approaches. The construction of polytene chromosome maps facilitated the development, characterization, and improvement of genetic sexing strains, which have boosted the effectiveness of SIT and are considered as models for developing genetic sexing methodologies in other target species. In parallel, characterization of mitotic karyotypes and the availability of polytene chromosomes in Diptera have been and are being used as supplementary evidence in taxonomic studies. Lately, under the common understanding that speciation can be achieved via various pathways and under the umbrella of integrative taxonomy, cytogenetic studies have contributed to multidisciplinary taxonomic approaches. Such studies can shed light on the borders between closely related species and/or incipient speciation, and this is crucial both for the implementation of SIT and the revision/improvement of quarantine policies. In this review, we summarize the cytogenetic status of Tephritidae and discuss the contribution of cytogenetics to the development of genetic sexing strains in this family.

FISH-based mitotic and meiotic diakinesis karyotypes of Morus notabilis reveal a chromosomal fusion-fission cycle between mitotic and meiotic phases

Mulberry (Morus spp.), in family Moraceae, is a plant with important economic value. Many polyploid levels of mulberry have been determined. In the present study, the fluorescence in situ hybridization (FISH) technique was applied in Morus notabilis, using four single-copy sequences, telomere repeats, and 5S and 25S rDNAs as probes. All the mitotic chromosomes were clearly identified and grouped into seven pairs of homologous chromosomes. Three dot chromosome pairs were distinguished by the FISH patterns of the 25S rDNA probe and a simple sequence repeat (SSR2524). According to the FISH signals, chromosome length and morphology, detailed meiotic diakinesis karyotype was constructed. Interestingly, only six bivalent chromosomes were observed in diakinesis cells. The 25S rDNA probe was used to illustrate chromosome alterations. The results indicated that mitotic chromosomes 5 and 7 fused into diakinesis chromosome 5 during the meiotic phase. In mitotic cells, the fused chromosome 5 broke into chromosomes 5 and 7. A chromosomal fusion-fission cycle between the meiotic and mitotic phases in the same individual is reported here for the first time. This finding will contribute to the understanding of karyotype evolution in plants.

The chromosomes and the mitogenome of Ceratitis fasciventris (Diptera: Tephritidae): two genetic approaches towards the Ceratitis FAR species complex resolution

Ceratitis fasciventris is a serious agricultural pest of the Tephritidae family that belongs to the African Ceratitis FAR species complex. Species limits within the FAR complex are obscure and multidisciplinary approaches have attempted to resolve phylogenetic relationships among its members. These studies support the existence of at least three additional species in the complex, C. anonnae, C. rosa and C. quilicii, while they indicate the presence of two structured populations (F1 and F2) within the C. fasciventris species. In the present study we present the mitotic karyotype, polytene chromosome maps, in situ hybridization data and the complete mitochondrial genome sequence of an F2 population of C. fasciventris. This is the first polytene chromosome map and complete mitogenome of a member of the FAR complex and only the second reported for the Ceratitis genus. Both polytene chromosomes and mitochondrial sequence could provide valuable information and be used as reference for comparative analysis among the members of the complex towards the clarification of their phylogenetic relationships.

Cytogenetic Characterization of Brown Howler Monkeys, Alouatta guariba clamitans (Atelidae, Platyrrhini): Meiotic Confirmation of an X1X1X2X2X3X3/X1X2X3Y1Y2 Sex Chromosome System

For brown howler monkeys (Alouatta guariba clamitans), diploid chromosome numbers varying from 2n = 45 to 2n = 52, with XX/XY, X₁X₁X₂X₂/X₁X₂Y, and X₁X₁X₂X₂X₃X₃/X₁X₂X₃Y₁Y₂ sex chromosome systems have been described by mitotic studies but still await confirmation by meiotic analyses. We analyzed 3 male individuals sampled in the wild (in the municipality of Santa Maria, RS, Brazil) as well as 1 male and 1 female individual in captivity at the São Braz breeding center. Peripheral blood samples and testicular biopsies were taken. We found different diploid numbers for both sexes in somatic cells, 2n = 45,X₁X₂X₃Y₁Y₂ in males and 2n = 46,X₁X₁X₂X₂X₃X₃ in females, with 4 metacentric (9-12), 7 submetacentric (1-6, 8), and 9 acrocentric autosomal chromosome pairs (13-20, 22). X₁ and X₂ were submetacentric chromosomes, while X₃, Y₁, and Y₂ were acrocentric ones. Spermatocyte microspreads were examined for synaptonemal complexes. Pachytene spermatocyte analysis was done to verify the chromosome number and morphologies observed in mitotic karyotypes. Immunodetection was performed using anti-SMC3 and anti-CREST antibodies. The presence of a sex chromosome pentavalent X₁X₂X₃Y₁Y₂ in the males was confirmed by C-banding in metaphase I and by immunodetection in prophase I by the clear identification of 5 centromeres. The G-banded karyotype corresponded to that previously described for A. g. clamitans in the south of Brazil (Curitiba, Parana State, and Blumenau, Santa Catarina State) and for the Misiones Province, Argentina.

Cytogenetic Analysis of the South American Fruit Fly Anastrepha fraterculus (Diptera:Tephritidae) Species Complex: Construction of Detailed Photographic Polytene Chromosome Maps of the Argentinian Af. sp.1 Member.

Genetic and cytogenetic studies constitute a significant basis for understanding the biology of insect pests and the design and the construction of genetic tools for biological control strategies. Anastrepha fraterculus is an important pest of the Tephritidae family. It is distributed from southern Texas through eastern Mexico, Central America and South America causing significant crop damage and economic losses. Currently it is considered as a species complex; until now seven members have been described based on multidisciplinary approaches. Here we report the cytogenetic analysis of an Argentinian population characterized as Af. sp.1 member of the Anastrepha fraterculus species complex. The mitotic karyotype and the first detailed photographic maps of the salivary gland polytene chromosomes are presented. The mitotic metaphase complement consists of six (6) pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement shows a total number of five long chromosomes that correspond to the five autosomes of the mitotic karyotype and a heterochromatic network corresponding to the sex chromosomes. Comparison of the polytene chromosome maps between this species and Anastrepha ludens shows significant similarity. The polytene maps presented here are suitable for cytogenetic studies that could shed light on the species limits within this species complex and support the development of genetic tools for sterile insect technique (SIT) applications.

Chromosome comparison of 17 species / sub-species of African Goliathini (Coleoptera, Scarabaeidae, Cetoniinae).

The mitotic karyotypes of 17 species of African Goliathini (Cetoniinae) are described using various chromosome banding techniques. All but one are composed of 20 chromosomes, mostly metacentric, forming a karyotype assumed to be close to that of the Polyphaga ancestor. The most derived karyotypes are those of Goliathus goliatus Drury, 1770, with eight pairs of acrocentrics and Chlorocana africana Drury, 1773, with only14 chromosomes. In species of the genera Cyprolais Burmeister, 1842, Megalorhina Westwood, 1847, Stephanocrates Kolbe, 1894 and Stephanorrhina Burmeister, 1842, large additions of variable heterochromatin are observed on both some particular autosomes and the X chromosome. Species of the genera Eudicella White, 1839 and Dicronorrhina Burmeister, 1842 share the same sub-metacentric X. Although each species possesses its own karyotype, it remains impossible to propose robust phylogenetic relationships on the basis of chromosome data only.

Male cytogenetic evaluation prior to assisted reproduction procedures performed in Mar del Plata, Argentina

This paper aimed to estimate the frequency of occurrence and the types of chromosomal abnormalities found in 141 infertile men with abnormal semen parameters. the frequency and type of chromosomal abnormalities were determined with male mitotic karyotype analysis from peripheral blood through chromosome banding techniques before assisted reproduction procedures. In this series of 141 infertile men, 19 (13%) had chromosomal anomalies and 35 (25%) had polymorphic variants. The main chromosome abnormalities were reciprocal translocations and marker chromosomes in mosaic. These results stress the relevance of cytogenetic studies for infertile males as a diagnostic tool and a valuable input in genetic counseling.

Systematics of theAnopheles barbirostrisspecies complex (Diptera: Culicidae: Anophelinae) in Thailand

This study deals with five species of the Barbirostris Complex of Anopheles subgenus Anopheles that are known to occur in Thailand. Three new species of the complex, Anopheles dissidens sp. nov., Anopheles saeungae sp. nov., and Anopheles wejchoochotei sp. nov., are characterized and compared with Anopheles barbirostris van der Wulp and Anopheles campestris Reid based on specimens of molecularly identified progeny broods. For practical purposes, the five species are essentially isomorphic and can only be unequivocally identified from diagnostic mitochondrial and ribosomal DNA sequences. Based on overall morphological similarity, An. campestris is considered to be a member of the Barbirostris Complex rather than a separate member of the Barbirostris Subgroup. The molecular data, mitotic karyotypes, bionomics, and distributions of the species are reviewed and discussed. It is concluded that integrated molecular epidemiological studies of the complex throughout the Oriental Region are needed to unambiguously elucidate the individual species and their relation to disease. © 2015 The Linnean Society of London

Cytological study onHippocrepis ciliataL. andHippocrepis unisiliquosassp.unisiliquosaL. (Leguminosae) in Turkey

Somatic chromosome numbers and karyotype of Hippocrepis unisiliquosa ssp. unisiliquosa L. and Hippocrepis ciliata L. (Leguminosae) collected from Turkey were examined. Chromosome numbers were determined as 2n = 2x = 14 in Hippocrepis unisiliquosa ssp. unisiliquosa L. and Hippocrepis ciliata. The mitotic chromosome number and karyotype of the taxa were reported here for the first time.

Karyotype revised of Pisum sativum using chromosomal DNA amount

Pisum sativum was one of the first plants for which the mitotic karyotype was recognized and the karyogram assembled. These achievements were required owing to the physical mapping of P. sativum, providing data for evolutionary approaches and breeding programs. In spite of significant advances, precise morphometric characterization of chromosomes and karyogram assembly of P. sativum have become a topical problem. The present study proposes an unambiguous classification for the chromosomes of P. sativum, based on classical cytogenetic rules and chromosomal DNA amount. Cytogenetic procedure yielded mitotic cells showing morphologically preserved and stoichiometrically stained chromosomes. Twelve mitotic cells were selected, and the mean values for total, short- and long-arm lengths and DNA amount were measured for each chromosome. Chromosomal DNA amount fully correlated with total chromosome length, whose value proportionally decreases with the amount of DNA. Considering these data, all seven chromosomes could be unambiguously identified, yielding a new cytogenetic classification for P. sativum chromosomes. Moreover, the chromosome pairs were ordered according to the classical cytogenetic rule for assembly of karyograms. Since P. sativum is considered a model plant, it was possible to correlate the newly outlined karyotype with other cytogenetic data and linkage groups.