Nucleolar Organizer Research Articles

Chromatin behavior in living cells: Lessons from single-nucleosome imaging and tracking.

Eukaryotic genome DNA is wrapped around core histones and forms a nucleosome structure. Together with associated proteins and RNAs, these nucleosomes are organized three-dimensionally in the cell as chromatin. Emerging evidence demonstrates that chromatin consists of rather irregular and variable nucleosome arrangements without the regular fiber structure and that its dynamic behavior plays a critical role in regulating various genome functions. Single-nucleosome imaging is a promising method to investigate chromatin behavior in living cells. It reveals local chromatin motion, which reflects chromatin organization not observed in chemically fixed cells. The motion data is like a gold mine. Data analyses from many aspects bring us more and more information that contributes to better understanding of genome functions. In this review article, we describe imaging of single-nucleosomes and their tracked behavior through oblique illumination microscopy. We also discuss applications of this technique, especially in elucidating nucleolar organization in living cells.

Could Argyrophilic Nucleolar Organizer Regions count mirror DNA Ploidy in Malignant Salivary Gland Tumors?

Objective:Nucleolar organizer regions (NORs) are DNA coils that transcribe to ribosomal RNA. The NOR-associated protein, termed argyrophilic NOR (AgNOR), was visible within the nucleus by staining with silver nitrate examination via the light microscope. AgNOR counting is a proliferation marker and may help in the diagnosis and prognosis of various neoplastic lesions. Aneuploidy (abnormal DNA content) can predict the progression, survival and prognosis of the tumors. The aim of this study was to evaluate the role of AgNORs, DNA ploidy status, and total S-phase fraction (TSPF) as prognostic parameters in malignant salivary gland tumors (MSGTs). Methods:The current study is a retrospective study on a cohort of MSGTs (N=47), to assess AgNORs using Silver Nitrate stain, DNA index (DI), and TSPF using flow cytometry (FCM). Data including tumor size and site, lymphovascular invasion (LVI), lymph node metastasis (LNM) were collected. Results:The AgNORs count was statistically significant with MSGT type. DI was found to have a significant association with tumor site, tumor size and MSGT type. In addition, TSPF was found to be significantly associated with LVI. A moderate positive correlation was noted between AgNORs count and TSPF. LNM, tumor site, high AgNORs and low DI were all associated with short disease-free survival (DFS) and poor overall survival (OS). Conclusion:The present study revealed that high AgNORs count, DNA aneuploidy and TSPF had a poor influence on MSGTs prognosis.

A near-complete assembly of an Arabidopsis thaliana genome

The genome sequence of Arabidopsis thaliana, a widely adopted model species, has greatly expedited plant molecular biology research. Over 20 years after the first release of the genome sequence (Arabidopsis Genome Initiative, 2000), there remains unresolved gap regions that are presumably composed of highly repetitive sequences, such as telomeres, centromeres, 5S rDNA clusters, and nucleolar organizer regions (NORs) containing 45S rDNA. It is difficult to assemble such repeats using comparatively short sequencing reads.

31. Rare familial rearrangement with acrocentric satellite material on Yp relocating to Xp in a female fetus

The short (p) arms of acrocentric chromosomes contain chromatin material described as stalks and satellites made up of repetitive DNA sequences including those encoding ribosomal RNA, and correspond to the nucleolar organizer regions (NOR). Satellites observed on non-acrocentric chromosomes are rare aberrations, typically resulting from translocation between the p-arm of an acrocentric chromosome and the distal arm of another chromosome. The phenotypic consequences of such unbalanced rearrangements can vary significantly depending on the size and gene content of the non-acrocentric chromosome involved.

Sequencing of laser captured Z and W chromosomes of the tocantins paradoxical frog (Pseudis tocantins) provides insights on repeatome and chromosomal homology.

Pseudis tocantins is the only frog species of the hylid genus Pseudis that possesses highly heteromorphic sex chromosomes. Z and W chromosomes of Ps. tocantins differ in size, morphology, position of the nucleolar organizer region (NOR) and the amount and distribution of heterochromatin. A chromosomal inversion and heterochromatin amplification on the W chromosome were previously inferred to be involved in the evolution of this sex chromosome pair. Despite these findings, knowledge related to the molecular composition of the large heterochromatic band of this W chromosome is restricted to the PcP190 satellite DNA, and no data are available regarding the gene content of either the W or the Z chromosome of Ps. tocantins. Here, we sequenced microdissected Z and W chromosomes of this species to further resolve their molecular composition. Comparative genomic analysis suggests that Ps. tocantins sex chromosomes are likely homologous to chromosomes 4 and 10 of Xenopus tropicalis. Analyses of the repetitive DNA landscape in the Z and W assemblies allowed for the identification of several transposable elements and putative satellite DNA sequences. Finally, some transposable elements from the W assembly were found to be highly diverse and divergent from elements found elsewhere in the genome, suggesting a rapid amplification of these elements on the W chromosome.

Study and Physical Mapping of the Species-Specific Tandem Repeat CS-237 Linked with 45S Ribosomal DNA Intergenic Spacer in Cannabis sativa L.

Hemp (Cannabis sativa L.) is a valuable crop and model plant for studying sex chromosomes. The scientific interest in the plant has led to its whole genome sequencing and the determination of its cytogenetic characteristics. A range of cytogenetic markers (subtelomeric repeat CS-1, 5S rDNA, and 45S rDNA) has been mapped onto hemp’s chromosomes by fluorescent in situ hybridization (FISH). In this study, another cytogenetic marker (the tandem repeat CS-237, with a 237 bp monomer) was found, studied, and localized on chromosomes by FISH. The signal distribution and karyotyping revealed that the CS-237 probe was localized in chromosome 6 with one hybridization site and in chromosome 8 with two hybridization sites, one of which colocalizes with the 45S rDNA probe (with which a nucleolus organizer region, NOR, was detected). A BLAST analysis of the genomic data and PCR experiments showed that the modified CS-237 monomers (delCS-237, 208 bp in size) were present in the intergenic spacers (IGSs) of hemp 45S rDNA monomers. Such a feature was firstly observed in Cannabaceae species. However, IGS-linked DNA repeats were found in several plant species of other families (Fabaceae, Solanaceae, and Asteraceae). This phenomenon is discussed in this article. The example of CS-237 may be useful for further studying the phenomenon as well as for the physical mapping of hemp chromosomes.

POS0863 ANTI-NOR90 ANTIBODIES IN THE SETTING OF CONNECTIVE TISSUE DISEASE: CLINICAL SIGNIFICANCE AND COMPARISON WITH A COHORT OF PATIENTS WITH SYSTEMIC SCLEROSIS

BackgroundAnti-NOR90 antibodies are directed against a 90-kD nucleolar protein located in the nucleolus organizing regions (NORs), mainly described in systemic sclerosis (SSc) [1, 2, 3] but reported also in other rheumatologic and oncologic diseases [4, 5, 6]. The clinical correlates of anti-NOR90 antibodies are still to be defined because the cohorts described thus far include a low number of patients.ObjectivesTo describe the characteristics of a large cohort of anti-NOR90 antibodies positive patients and compare them with a matched cohort of SSc patients negative for anti-NOR90 antibodies.MethodsA retrospective analysis was performed on patients positive for anti-NOR90 antibodies referring to participating centres. The concomitant positivity for anti-RNA polymerase III, Th/To, PM-Scl, Ku, and PDGFR antibodies was an exclusion criterion. In all cases the diagnoses, the different organ involvement and related clinical, instrumental and laboratory characteristics were evaluated. The EUROLINE SystemicSclerosisProfile kit from Euroimmun (Lübeck, Germany) was used to detect anti-NOR90 antibodies.ResultsWe included 101 patients positive for anti-NOR90 (M/F=13/88, mean age 52.5 years). They were mainly classified as SSc (n=38), undifferentiated connective tissue disease (UCTD) (n=21), interstitial pneumonia with autoimmune features (IPAF) (n=11) (graph 1). The most frequent clinical manifestations were arthralgias (n=72), Raynaud’s phenomenon (RP) (n=58), sicca syndrome (n=49), ILD (n=40), puffy fingers (n=32), arthritis (n=30), and limited skin sclerosis (n=24). Anti-NOR90 antibodies were associated with anti-Ro52 antibodies in the 16% of cases, with anticentromere antibodies in the 7% of cases, and with anti-Scl70 in the 5% of cases. After excluding these patients, and considering the isolated anti-NOR90 positivity, 12 patients had SSc, 35 UCTD, and 11 IPAF. The most frequent clinical manifestations were arthralgias (n=40), RP (n=37), and sicca syndrome (n=21). Compared to 242 matched SSc without anti-NOR90 antibodies, patients with anti-NOR90 had more frequently joint manifestations and sicca syndrome and less frequently all vasculopathic manifestations (RP, telangiectasias, pitting scars, acral ulcers), dysphagia and fibromyalgia.ConclusionOur study shows that anti-NOR90 antibodies are more commonly observed in females, and clinically associated with the occurrence of arthritis/arthralgias, sicca syndrome and RP. In more than the 50% of cases they may be found with other autoantibodies, such as the anti-Ro52, the anticentromere, and the anti-Scl70 antibodies. Anti-NOR90 seems to play an accompanying role in the context of CTDs, without strong influence on the clinical phenotype expression of the underlying CTD.

Ribosomal DNA transcription is increased in the left nucleus accumbens of heroin-dependent males.

Opioid addiction is a worldwide problem accentuated in the USA and European countries by the COVID-19 pandemic. The nucleus accumbens (NAc) plays an outstanding neurobiological role in opioid addiction as a part of the striatum and key component of brain reward system. The striatal GABAergic medium spiny projection neurons (MSNs) are the main neuronal type in the NAc where addiction-specific synaptic plasticity occurs. The activity of ribosomal DNA (rDNA) transcription is crucial for neural plasticity and molecular studies suggest its increase in the NAc of heroin addicts. Silver-stained argyrophilic nucleolar organizer region (AgNOR) areas visualised in neuronal nuclei in paraffin-embedded brain sections are reliable morphological estimators of rDNA transcription and thus surrogate markers for the activity of brain regions. Our study revealed increased AgNOR areas in MSNs of the left NAc in 11 heroin addicts versus 11 healthy controls from the Magdeburg Brain Bank (U-test P = 0.007). No differences were observed in another investigated part of the striatum, namely the head of caudate nucleus, which is located closely to the NAc. The results were not confounded by significant differences in the age, brain volume and time of formalin fixation existing between compared groups. Our findings suggest an increased NAc activity in heroin addicts, which is consistent with human and animal experimental data.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00406-022-01423-7.

Low level of Fibrillarin, a ribosome biogenesis factor, is a new independent marker of poor outcome in breast cancer

BackgroundA current critical need remains in the identification of prognostic and predictive markers in early breast cancer. It appears that a distinctive trait of cancer cells is their addiction to hyperactivation of ribosome biogenesis. Thus, ribosome biogenesis might be an innovative source of biomarkers that remains to be evaluated.MethodsHere, fibrillarin (FBL) was used as a surrogate marker of ribosome biogenesis due to its essential role in the early steps of ribosome biogenesis and its association with poor prognosis in breast cancer when overexpressed. Using 3,275 non-metastatic primary breast tumors, we analysed FBL mRNA expression levels and protein nucleolar organisation. Usage of TCGA dataset allowed transcriptomic comparison between the different FBL expression levels-related breast tumours.ResultsWe unexpectedly discovered that in addition to breast tumours expressing high level of FBL, about 10% of the breast tumors express low level of FBL. A correlation between low FBL mRNA level and lack of FBL detection at protein level using immunohistochemistry was observed. Interestingly, multivariate analyses revealed that these low FBL tumors displayed poor outcome compared to current clinical gold standards. Transcriptomic data revealed that FBL expression is proportionally associated with distinct amount of ribosomes, low FBL level being associated with low amount of ribosomes. Moreover, the molecular programs supported by low and high FBL expressing tumors were distinct.ConclusionAltogether, we identified FBL as a powerful ribosome biogenesis-related independent marker of breast cancer outcome. Surprisingly we unveil a dual association of the ribosome biogenesis FBL factor with prognosis. These data suggest that hyper- but also hypo-activation of ribosome biogenesis are molecular traits of distinct tumors.

New cytogenetic data on Caryophyllaeus laticeps and Paracaryophyllaeus gotoi, parasites of evolutionary interest.

Caryophyllideans are intestinal parasites of freshwater fishes, occupying a basal position among the ‘true’ tapeworms. We performed detailed cytogenetic analyses of the well-known caryophyllidean species Caryophyllaeus laticeps. For comparison, we also examined for the first time the chromosomes of Paracaryophyllaeus gotoi, a specific parasite of loaches in China. Both species showed a diploid chromosome number of 2n = 20, n = 10m. Chromomycin A3 (CMA3)/diamidino-2-phenylindole (DAPI) staining performed for the first time in the class Cestoda revealed CMA3+/DAPI− bands in the pericentromeric regions of the short arms of chromosome pair no. 7 in the karyotype of C. laticeps. Fluorescence in situ hybridization with the 18S rDNA probe confirmed the presence of a single cluster of major rDNA near the centromere on a pair of small chromosomes in both species. These findings support the hypothesis that the ancestral state in the family Caryophyllaeidae is a single interstitial cluster of major rDNA genes and thus one nucleolar organizer region per haploid genome. Our results, which we presented together with literature data plotted on a phylogenetic tree, show stability of caryophyllidean karyotypes at the genus level, but showed differences between genera without a clear phylogenetic signal. The data allowed us to at least formulate a hypothesis about the ancestral haploid chromosome number of n = 10 for the family Caryophyllaeidae and possibly for the sister family Capingentidae. In addition, we compared two populations of C. laticeps from water bodies with different levels of polychlorinated biphenyl contamination, showing a slightly increased incidence of chromosomal abnormalities at the contaminated site.

Cytogenetic analysis of two species of genus Protosticta from Himachal Pradesh, India

Cytogenetically, out of 262 species, only three species of family Platystictidae has been reported worldwide. Present study has been undertaken to study chromosome complement and its characterization of more species of this family. Cytogenetic analyses of Protosticta sanguinostigma Fraser, 1992 and Protosticta uncata Fraser, 1931 of family Platystictidae, collected from Andretta, Himachal Pradesh, India have been carried out on the basis of conventional staining, C-banding and silver nitrate staining. Both the species possess n=13m as haploid chromosome number and X0-XX sex determining mechanism. One large bivalent is present in all the meiotic stages of P. sanguinostigma which is considered as the species specific character. Chromosome complement of both the species shows variation in distribution of C-bands and Nucleolar organizer regions (NORs). Cytologically, both the species have been described for the first time.

Ancestral Chromosomes for Family Peronosporaceae Inferred from a Telomere-to-Telomere Genome Assembly of Peronospora effusa.

Downy mildew disease of spinach, caused by the oomycete Peronospora effusa, causes major losses to spinach production. In this study, the 17 chromosomes of P. effusa were assembled telomere-to-telomere, using Pacific Biosciences high-fidelity reads. Of these, 16 chromosomes are complete and gapless; chromosome 15 contains one gap bridging the nucleolus organizer region. This is the first telomere-to-telomere genome assembly for an oomycete. Putative centromeric regions were identified on all chromosomes. This new assembly enables a reevaluation of the genomic composition of Peronospora spp.; the assembly was almost double the size and contained more repeat sequences than previously reported for any Peronospora species. Genome fragments consistently underrepresented in six previously reported assemblies of P. effusa typically encoded repeats. Some genes annotated as encoding effectors were organized into multigene clusters on several chromosomes. Putative effectors were annotated on 16 of the 17 chromosomes. The intergenic distances between annotated genes were consistent with compartmentalization of the genome into gene-dense and gene-sparse regions. Genes encoding putative effectors were enriched in gene-sparse regions. The near-gapless assembly revealed apparent horizontal gene transfer from Ascomycete fungi. Gene order was highly conserved between P. effusa and the genetically oriented assembly of the oomycete Bremia lactucae; high levels of synteny were also detected with Phytophthora sojae. Extensive synteny between phylogenetically distant species suggests that many other oomycete species may have similar chromosome organization. Therefore, this assembly provides the foundation for genomic analyses of diverse oomycetes.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Cytogenetic Analysis of Alburnus escherichii (Teleostei: Leuciscidae) in Turkey

In this study, cytogenetic properties of A. escherichii were investigated using standard Giemsa staining, C-banding, and Ag-NOR staining techniques. The karyotype of Sakarya bleak, the diploid chromosome number was 2n = 50, consists of six pairs of metacentric, 12 pairs of submetacentric, and seven pairs of acrocentric autosomes (NF=86). No morphologically distinguishable heteromorphic sex chromosomes were detected in the karyotype. While most autosomes had centromeric and pericentromeric C-heterochromatin (some chromosomes slightly) blocks, the other autosomal pairs were C-negative. Also, the short arm of the eleventh submetacentric chromosome pair was entirely C-positive. The nucleolar organizer regions were localized in medium-sized submetacentric autosomal pairs. Active NORs associated with the C-heterochromatin were observed in the whole of the short arm of the eleventh chromosome pair, and their active NORs were homomorphic. The banded karyotypes of A. escherichii were reported in this study for the first time. Significant findings obtained in this research may contribute to cytotaxonomy of Alburnus species in Anatolian and Europe.

A critical review on cytogenetics of Cucurbitaceae with updates on Indian taxa.

The cytogenetic relationships in the species of Cucurbitaceae are becoming immensely important to answer questions pertaining to genome evolution. Here, a simplified and updated data resource on cytogenetics of Cucurbitaceae is presented on the basis of foundational parameters (basic, zygotic and gametic chromosome numbers, ploidy, genome size, karyotype) and molecular cytogenetics. We have revised and collated our own findings on seven agriculturally important Indian cucurbit species in a comparative account with the globally published reports. Chromosome count (of around 19% species) shows nearly three-fold differences while genome size (of nearly 5% species) shows 5.84-fold differences across the species. There is no significant correlation between chromosome numbers and nuclear genome sizes. The possible trend of evolution is discussed here based on molecular cytogenetics data, especially the types and distribution of nucleolus organizer regions (NORs). The review supersedes the scopes of general chromosome databases and invites scopes for continuous updates. The offline resource serves as an exclusive toolkit for research and breeding communities across the globe and also opens scope for future establishment of web-database on Cucurbitaceae cytogenetics.

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.

Adapted technique for demonstrating argyrophilic nucleolar organizer regions in the cytologic samples of canine mast cell tumors.

Argyrophilic nucleolar organizer regions (AgNORs) are nonhistone argyrophilic nucleolar proteins associated with ribosomal genes found in the nucleolar organizer region that reflect cell proliferation and have an affinity for silver. AgNOR staining may be useful to evaluate prognosis in several neoplasms because higher AgNOR counts are related to higher grade tumors, metastases, and shorter survival times. We aimed to report on a quick and practical technique to identify AgNORs adapted for use in routine cytology. The cytopathologic diagnosis of mast cell tumor (MCT) in samples collected by fine-needle aspiration (FNA) was determined. Next, slides were impregnated with a solution containing silver nitrate; the main modification of our technique included incubation of these slides at a controlled temperature of 25 °C. Some slides were previously stained with Diff-Quik and others were only fixed with methanol. The slides were analyzed under a microscope, and the number of blackened intranuclear points (AgNORs) was counted. Slides prestained with Diff-Quik were easily counted compared with slides only fixed in methanol. Technical issues encountered with the methanol-fixed slides included insufficient cellularity, background precipitation, and an absence of silver impregnation. The technique reported in this study showed satisfactory results for AgNOR counting in cytologic smears from MCT, such as good impregnation and the elimination of background interferents. Further evaluation of this method comparing AgNOR counts with histologic examinations, tumor grades, other prognostic markers, and survival times are needed to fully evaluate the benefit of this technique.

“STUDY OF PROLIFERATIVE INDICES USING MITOTIC INDEX AND AGNOR AND THEIR CORRELATION WITH VARIOUS GRADES OF BREAST CARCINOMA”

Background: Breast cancer is a leading cause of death in women. The objectives of this study were to compare the argyrophilic nucleolar organizer region (AgNOR) count and mitotic index with various histological grades of infiltrating ductal carcinoma of breast. Aim: To study the relationship of the proliferative indices and various grades of breast carcinoma. Objective: "Study of proliferative indices using mitotic index and Agnor and their correlation with various grades of breast carcinoma" Material and Method: In this prospective study all specimens of infiltrating ductal carcinoma of female breast belonging to all age groups received in the department of histopathology of Gajra Raja Medical College,Gwalior during the period of three years were graded using Bloom and Richardson score and correlated with proliferative indices mitotic index and AgNOR counts. Result: The mean Age (Years) was 46.16 ± 8.68.The mean B&R Score was 6.52 ± 1.20.The mean Mitotic Index was 8.51 ± 2.61.The mean AgNOR Count was 4.24 ± 2.34.There was significant correlation between AgNOR count,mitotic index and histological grades. Conclusion: AgNOR count and mitotic index can be used as reliable proliferative indices which correlate well with the histological grades and are cost effective too.

Chromosome Comparisons of Australian Scaptodrosophila Species

Simple SummaryScaptodrosophila are a diverse group of flies that are widespread in Australia but have received limited research attention. In this study, we characterized the chromosomes of 12 Scaptodrosophila species. We found that the structural changes in their chromosomes are very similar to those seen in Drosophila, a related genus of flies. This includes the amplification of repetitive elements and changes in chromosome length in small (dot) chromosomes and the sex chromosomes. We also found numerous weak points along the arms of polytene chromosomes, which suggest the presence of internal repetitive sequences. Regions producing the nucleolus are at the same chromosome positions in Scaptodrosophila and Drosophila. These chromosomal studies provide a foundation for future genetic studies in Scaptodrosophila flies.The Scaptodrosophila represent a diverse group of Diptera closely related to Drosophila. Although they have radiated extensively in Australia, they have been the focus of few studies. Here, we characterized the karyotypes of 12 Scaptodrosophila species from several species groups and showed that they have undergone similar types of karyotypic change to those seen in Drosophila. This includes heterochromatin amplification involved in length changes of the sex and ‘dot’ chromosomes as well as the autosomes, particularly in the coracina group of species. Numerous weak points along the arms of the polytene chromosomes suggest the presence of internal repetitive sequence DNA, but these regions did not C-band in mitotic chromosomes, and their analysis will depend on DNA sequencing. The nucleolar organizing regions (NORs) are at the same chromosome positions in Scaptodrosophila as in Drosophila, and the various mechanisms responsible for changing arm configurations also appear to be the same. These chromosomal studies provide a complementary resource to other investigations of this group, with several species currently being sequenced.

Cytogenetic and Molecular Characterization of Oligosarcus pintoi (Characidae): A New Record of Supernumerary Chromosome in this Species.

The genus Oligosarcus currently comprises 24 valid species distributed in the major river basins of South America. In this group, nine species were cytogenetically investigated, and found to share a diploid number of 50 chromosomes. Despite the conservation of the diploid number, variations in the karyotypic formula, number and position of the nucleolar organizer regions, and longitudinal bands have been described between both species and populations. In this study, we present cytogenetic and molecular data from Oligosarcus pintoi specimens from the Keller River, a tributary of the Ivaí River (Upper Paraná basin), using DNA barcoding and cytogenetic markers (C-band, silver-stained nucleolar organizer regions, and fluorescence in situ hybridization of 18S and 5S rDNA). The genetic inferences reached after analyzing the cytochrome c oxidade subunit 1 gene allowed us to confirm the identity of the individuals with 2n = 50 chromosomes. However, one specimen contained a medium subtelocentric supernumerary chromosome (2n = 51). This is the second record of additional chromosomes in O. pintoi, thereby confirming the existence of a supernumerary chromosome in allopatric populations of this species, a fact that demonstrates an evolutionary path that is divergent from other populations and/or species of Oligosarcus analyzed so far, contributing to the karyotypic diversification of the group.

Analysis of Argyrophilic Nucleolar Organizer Regions (AgNORs) in Acute Leukemia in Adults.

The evaluation of argyrophilic nucleolar organizer regions (AgNORs) uses a simple method used in research into neoplasm. Bone marrow aspirates from 70 patients with acute leukemia underwent morphological, immunophenotypic, and genetic assessment and were stained with silver nitrate. In leukemic cells, the mean AgNORs number, mean AgNORs area, and mean AgNOR-area-to-nucleus-area ratio were calculated in patients with acute myeloid leukemia (AML), patients with acute lymphoblastic leukemia (ALL), and selected risk groups. A higher value of all measured AgNOR parameters was observed in patients with AML compared to the ALL group. In AML patients, a higher mean AgNOR area was found in the ELN3 cytogenetic group compared to the ELN2 cytogenetic group. A higher value of the mean AgNOR count was observed in patients with white blood cells (WBCs) > 12 × 109/L than in the group with WBCs ≤ 12 × 109/L, as well as in patients with >20% blasts in peripheral blood (PB) than in patients with ≤20% blasts in PB. In the ALL group, a higher mean AgNOR-area-to-nucleus-area ratio was found in group with the presence of Philadelphia chromosome Ph(+) than without the Philadelphia chromosome Ph(−). AgNOR parameter analysis is a valuable method for differentiation of AML and ALL in adults.