Nucleolar Organizer Region Staining Research Articles

Effects of the interaction between hydroxyapatite nanoparticles and hepatoma cells

To gain a better understanding of the anticancer effects of hydroxyapatite (HAP) nanoparticles in vivo and in vitro, the effects of the interaction of HAP nanoparticles with hepatoma cells were explored. HAP nanoparticles were prepared by homogeneous precipitation and characterized by laser particle analysis and transmission electron microscopy (TEM). HAP nanoparticles were observed to be uniformly distributed, with rod-like shapes and diameters in the range of 42.1–87.1 nm. Overnight attached, suspended, and proliferating Bel-7402 cells were incubated with HAP nanoparticles. Inverted microscopy observation revealed that HAP nanoparticles with a cell membrane showed good adsorption. TEM demonstrated that HAP nanoparticles were present on the surface of cells, continuously taken up by cells through endocytosis, and transported in vesicles close to the nucleus. Fluorescence microscopy showed that the concentrations of intracellular Ca2+ labeled with Fluo-3 calcium fluorescent probe were significantly enhanced. In addition, inverted microscopy observation revealed that suspended cells treated with HAP nanoparticles did not adhere to the culture bottle, resulting in cell death. After the overnight attached cells were treated with HAP nanoparticles for 96 h with increasing doses of HAP nanoparticles, inverted microscopy observation revealed that cell proliferation was slowed and cell-cell adhesion was weakened. Feulgen staining and image analysis indicated that the nuclear DNA content of the cells was markedly reduced, and argyrophilic nucleolar organizer region (AgNOR) staining and image analysis indicated that the number of AgNORs was significantly decreased. Therefore, hepatoma cells brought about the adsorption, uptake, transport and degradation of HAP nanoparticles. In addition, HAP nanoparticles affected hepatoma cells with regard to cell-cell adhesion, cell and extracellular matrix adhesion, and DNA and protein synthesis; thus inhibiting cell proliferation. This understanding of the effects of interaction between HAP nanoparticles and hepatoma cells is useful for further study of the anticancer mechanisms of HAP nanoparticles.

Is one-time carbon monoxide intoxication harmless? Evaluation by argyrophilic nucleolar-organizing regions staining method.

In carbon monoxide (CO) poisoning, CO affects the oxygen-carrying capacity of the hemoglobin molecule. Nucleolar-organizing regions (NORs) are genetic loci on chromosomes that are composed of ribosomal DNA and proteins. NORs can be stained with silver. A total of 18 rats were exposed to CO in three different concentrations (1000, 3000, and 5000 ppm) with 6 rats as controls. The animals were euthanized 7 days after CO intoxication. Lung tissues were taken, embedded in paraffin blocks, and sectioned at 5 μm thickness. Argyrophilic nucleolar-organizing region (AgNOR) staining was carried out. One hundred nuclei per individual were evaluated, and total AgNOR number per total nuclear number and total AgNOR area per nuclear area (TAA/NA) for each nucleus were analyzed. The CO exposure groups had significantly higher TAA/NA values and AgNOR numbers than the control group (p < 0.05). Although the differences between 1000 ppm and the other two CO-exposed groups were meaningful (p < 0.05) in the TAA/NA values, there were no differences among the CO exposure groups for the AgNOR number (p > 0.05). The increase in TAA/NA value depends on the increase in the CO exposure. Significant correlations between both the AgNOR values and histopathological scoring methods were found. Therefore, AgNOR staining method may be used as an indirect indicator for evaluating the degree of cell damage rate.

Thymoquinone inhibits cell proliferation through regulation of G1/S phase cell cycle transition in N-nitrosodiethylamine-induced experimental rat hepatocellular carcinoma

Dysregulated cell proliferation and tumorigenesis is frequently encountered in several cancers including hepatocellular carcinogenesis (HCC). Thus, agents that inhibit cell proliferation and restrain hepatic tumorigenesis through cell cycle regulation have a beneficial effect in the treatment of hepatocellular carcinogenesis. The present study was aimed to investigate the efficacy of thymoquinone (TQ), an active compound derived from the medicinal plant Nigella sativa, on N-nitrosodiethylamine (NDEA) [0.01% in drinking water for 16 weeks]-induced hepatocarcinogenesis in experimental rats. After experimental period, the hepatic nodules, liver injury markers and tumor markers levels were substantially increased in NDEA induced liver tumors in rats. However, TQ (20mg/kg body weight) treatment greatly reduced liver injury markers and decreased tumor markers and prevented hepatic nodule formation and reduced tumor multiplicity in NDEA induced hepatic cancer bearing rats and this was evident from argyrophilic nucleolar organizer region (AgNORs) staining. Moreover, the uncontrolled cell proliferation was assessed by specific cell proliferative markers [proliferating cell nuclear antigen (PCNA) and Ki67] by immunofluorescence, immunoblot and analysis of mRNA expression. Simultaneously, we assessed the activity of TQ on G1/S phase cell cycle regulation with specific cell cycle proteins (p21WAF1/CIP1, CDK4, Cyclin D1 and Cyclin E) by immunoprecipitation in experimental rats. Treatment with TQ significantly reduced the detrimental alterations by abrogating cell proliferation, which strongly induced G1/S arrest in cell cycle transition. In conclusion, our results suggest that TQ has a potent anti proliferative activity by regulating the G1/S phase cell cycle transition and exhibit a beneficial role in the treatment of HCC.

Karyological and molecular diversity in three freshwater species of the genusChanna(Teleostei, Perciformes) from India

Genetic variability was assessed among three species of genus Channa, namely C. gachua, C. punctata and C. striata, using karyological tools including karyomorphology, silver nitrate and chromomycin A3 staining of nucleolar organizer regions (NORs) and C-banding. Additionally, sequence variation in partial 18S and divergent domain 1 of 28S ribosomal DNA was utilized for inter-species diversity assessment. Diploid chromosome numbers of 32, 40 and 52 in the three species were observed and the karyotype formula was derived as 18m + 12sm + 2st (fundamental arm number [FN] = 62); 6m + 2sm + 10st + 22t (FN = 48) and 12m + 10sm + 14st + 16t (FN = 86) in C. punctata, C. striata and C. gachua, respectively. Similarly, variations were also observed in number and location of silver and chromomycin A3 stained NORs and C-banding patterns. DNA sequencing generated sizes for 18S of 243, 248, 245 bp and for 28S of 401, 392 and 393 bp in C. gachua, C. punctata and C. striata, respectively. The results indicated that the cytogenetic and molecular markers are useful for the assessment of genetic diversity among the fish species and could provide valuable information for germplasm evaluation and ex situ conservation.

Study of AgNOR count and SAPA score in fine needle aspirates of breast lumps

Background: Argyrophilic Nucleolar Organizer Region technique has a potential value in the diagnosis of malignancy and can be used in cases with equivocal and inconclusive cytological picture. The purpose of this study was to evaluate mean Argyrophilic Nucleolar Organizer Region count and Subjective Argyrophilic Nucleolar Organizer Region Pattern Assessment score in fi ne needle aspirates of breast lumps. Materials and Methods: A prospective, cross sectional study consisting of 110 patients (38 malignant and 72 benign) with clinically palpable breast lumps who underwent fi ne needle aspiration followed by subsequent histopathologic examination were included. Fine Needle Aspiration smears were studied by conventional methods and silver staining for Argyrophilic Nucleolar Organizer Regions. Histopathologic diagnosis was taken as the gold standard. Results: Argyrophilic Nucleolar Organizer Region count and Subjective Argyrophilic Nucleolar Organizer Region Pattern Assessment score were helpful in differentiating benign from malignant lesions. Mean Argyrophilic Nucleolar Organizer Region count and Subjective Argyrophilic Nucleolar Organizer Region Pattern Assessment score were 2.63 ± 1.36 and 6.26 ± 1.19 respectively in benign lesions while they were 8.42 ± 2.53 and 10.05 ± 2.22 respectively in malignant lesions. With few exceptions, cases with high counts had high scores. Conclusion: Mean Argyrophilic Nucleolar Organizer Region AgNOR count and Subjective Argyrophilic Nucleolar Organizer Region Pattern Assessment score provide useful information regarding cellular proliferation. Both count and score have comparable diagnostic potential but the latter is a more convenient and rapid method for Argyrophilic Nucleolar Organizer Region evaluation. DOI: http://dx.doi.org/10.3126/jkmc.v1i1.7248 Journal of Kathmandu Medical College, Vol. 1, No. 1, Issue 1, Jul.-Sep., 2012 pp.3-9

Polyploidy, B chromosomes, and heterochromatin characterization of Mimosa caesalpiniifolia Benth. (Fabaceae-Mimosoideae)

Eight populations of Mimosa caesalpiniifolia Benth. were investigated using a cytogenetic approach. Here, we describe for the first time details of the karyotype including chromosome morphology, physical mapping of chromomycin A3 (CMA) 4′,6-diamidino-2-phenylindole (DAPI) and silver staining of nucleolar organizer regions (Ag-NOR banding), as well as 45S rDNA sites. All populations studied showed karyotypes with 2n = 2x = 26 small metacentric and submetacentric chromosomes, although some individuals exhibited 2n = 4x = 52 chromosomes. Moreover, we observed putative additional B chromosomes in some populations. The CMA banding and fluorescent in situ hybridization techniques revealed NOR heteromorphism on the unique pair containing 45 rDNA site (chromosome 12) while the Ag-NOR banding indicated NORs on both cytotypes. Up to two and four nucleoli were observed, respectively, on individuals with 2n = 2x = 26 and 2n = 4x = 52 chromosomes and the differences in nucleolar size seems to be directly related to NOR heteromorphism in some individuals. The data present new and important information to understand karyotypic evolution of Mimosa and Fabaceae.

The Role of Argyrophilic Nucleolar Organizer Region (AgNOR) Study in Cytological Evaluation of Fluids, Especially for Detection of Malignancy

Serous effusion smears reported as (suspicious for malignancy) pose problems in clinical management. Silver staining for argyrophilic nucleolar organizer regions (AgNOR) has proved useful in making a cytopathologic differential diagnosis between benign and malignant cells. Nucleolar organizer regions(NORs) are loops of DNA located in acrocentric chromosomes. These NORs are visualized by silver staining technique that recognizes these argyrophilia associated proteins which are increased in malignancy. This study aimed to distinguish reactive mesothelial cells from malignant cells in serous effusions using these NORs. A total of 174 serous effusions received at the Department of Pathology, TUTH, during a period of one year were included in the study. Smears were studied by conventional Papanicolaou and Giemsa stains. AgNOR counts, variation in size and dispersion of AgNOR dots in smears were graded and compared in malignant and non-malignant effusions. Mean AgNOR counts of 10.43+\-0.73 and 10.21+\-0.51 in malignant peritoneal and pleural effusions, respectively, were significantly (p < 0.0001) greater as compared with counts of 2.12 +\- 0.54 and 2.11 +\- 0.54 in non-malignant effusions. The AgNORs were irregular in shape in malignant effusions whereas they were comparatively larger, single dots in benign effusions. AgNOR size and dispersion were of higher grade in significantly greater proportion of malignant as compared with non malignant effusions (p < 0.0001). Of the cytologically suspicious samples, nine were in the malignant range and one was in the benign range. AgNOR study appears to be clinically useful as an additional diagnostic tool for use in serous effusion when the cytologic diagnosis is difficult.

Three patients with Wolf‐Hirschhorn syndrome carrying a satellited chromosome 4p

Wolf-Hirschhorn syndrome (WHS) is caused by a deletion involving the 4p16.3 region. Approximately 70% of WHS patients have a de novo isolated deletion and 22% involve unbalanced translocations. However, WHS with unbalanced rearrangements involving the short arm of an acrocentric chromosome are infrequently reported. Cytogenetic and molecular analyses by using standard G-banding, argyrophilic nucleolar organiser region (Ag-NOR) staining, fluorescence in situ hybridization, and single nucleotide polymorphism array for copy number detection were performed in three patients with WHS phenotype from two Chinese families. A heterozygous 2,767,380-bp terminal 4p deletion was detected in patients 1 and 2 and a heterozygous 5,047,291-bp terminal 4p deletion was detected in patient3. Clinical comparisons among our patients and previously reported cases have been reviewed. Two terminal 4p deletions were identified in three WHS patients with a satellited 4p and an attempt was made to refine the genotypic-phenotypic correlations of the deleted regions.

Nucleolar organizer regions in a chronic stress and oral cancer model

This study aimed to examine the role of chronic restraint stress (RS) on oral squamous cell carcinomas induced by 4-nitroquinoline-1-oxide (4-NQO) in CF-1 mouse tongues, measured by the expression of argyrophilic staining of nucleolar organizer regions (AgNOR). Thirty one samples of lingual epithelial tissue of CF-1 mice with a diagnosis of oral squamous cell carcinoma (OSSC) were assigned to two experimental groups: the RS/4-NQO group, where animals received RS and induction of oral chemical carcinogenesis (n=17); and the 4-NQO group, where animals received induction of chemical carcinogenesis without restraint stress (n=14). The mean number and distribution pattern of AgNOR were recorded. The mean AgNOR number per cell was found to be slightly higher in the 4-NQO group. AgNOR in the RS/4-NQO group revealed a higher tendency to be arranged in a clumped distribution compared to the 4-NQO group. No statistically significant difference was found between the groups. In conclusion, the induction of chronic restraint stress in CF-1 mice does not increase the number or affect the distribution pattern of AgNORs in OSSC induced by 4-NQO.

Thesis Abstract Classical and molecular cytogenetic analysis in Chelonoidis carbonaria and Phrynops geoffroanus (Testudines)

The number of species of reptiles has decreased since the time that they ruled the Earth until the present days. Turtles have been little studied, particularly regarding their cytogenetics. The present study investigated, using classical and molecular cytogenetic techniques, the chromosomes of Chelonoidis carbonaria, a terrestrial species, and Phrynops geoffroanus, an endangered species that lives along the rivers, both in South America. Blood samples were collected from animals at the breeding farm Reginaldo Uvo Leone in Tabapua, SP. All procedures were approved by the Animal Ethics Committee (No. 50/07-CEEA, Botucatu, SP) and IBAMA/RAN (No. 14729-1). The metaphases were prepared from blood incubated in culture medium for lymphocytes, which were stimulated to divide by the addition of phytohemagglutinin. After this procedure, colchicine was added to inhibit the formation of spindle fibers, maintaining the cells in metaphase. We assessed male and female C. carbonaria, which had the same number of chromosomes, 2n = 52, and specimens of P. geoffroanus, which were described for the first time and showed females with 2n = 58 and males with 2n = 57 chromosomes. Using the G-banding technique it was possible to identify pairs of homologous chromosomes and with the C-banding technique, the presence of regions of constitutive heterochromatin in macrochromosomes and microchromosomes. Silver impregnation detected the nucleolar organizer regions (NORs) in two microchromosomes in males and only one of the microchromosomes in females in C. carbonaria. The same pattern was found in P. geoffroanus. The FISH technique revealed the presence of rRNA sites showing positive staining for NORs. This study showed the ability of classical and molecular cytogenetic techniques to identify the chromosomes of males and females of C. carbonaria and P. geoffroanus, terrestrial and aquatic species, respectively, making it possible to use them as a model for genetic and evolutionary studies.

Role of argyrophilic nucleolar organizer region staining in identification of malignant cells in effusion

Background:Cytological examination of effusions helps to differentiate between benign and malignant effusions, but fails a definitive diagnosis in a number of cases. The main problem here is to distinguish reactive mesothelial cells from neoplastic cells.Aim:In the present study, we used argyrophilic nucleolar organizer region (AgNOR) staining for diagnosis of benign and malignant effusions.Materials and Methods:In this study, 100 cases of effusion samples were taken and centrifuged. Four smears were prepared from sediment, one each for Leishman, hematoxylin and eosin (H and E) staining and two for AgNOR staining. AgNORs were counted as black dots in the nuclei of all abnormal cells using ×100 oil immersion objective. Their dispersion and shape was compared in benign, malignant and atypical cases.Results:Out of 50 pleural effusion samples, 29 were benign, 10 were malignant and 11 atypical. Among the 47 peritoneal effusion samples, 27 were benign, 16 were malignant and 4 atypical. Out of three cases of pericardial effusion samples, one was benign and two were malignant. All effusions were subjected to AgNOR staining. The benign group consisted of cells showing 1 to 2 dots of regular size and shape. In malignant group, 3 to 5 dots of variable size, shape and irregular contours were observed per cell. In atypical group, the reactive mesothelial cells showed 1 to 2 dots, malignant cells showed 3 to 4 irregular dots. Thus, a differentiation was noted between activated mesothelial cells and malignant cells, which was not possible in Leishman and H and E-stained smears alone.Conclusion:Therefore, AgNOR can be branded as an extremely useful additional diagnostic tool for cytodiagnosis of effusions.

Role of proliferative markers in breast lesions

Carcinoma of breast is a leading cause of death in women throughout the world. Difficulty in diagnosis occurs in routine Hematoxylin and Eosin (H&E) stained sections to differentiate premalignant lesions like epitheliosis and malignant lesions like carcinoma in situ which may affect prognosis. Our study was done to assess the role of proliferative markers in this field. In this study, total 66 cases of different breast lesions were studied by H&E stained sections as well as proliferative markers like silver staining nucleolar organizer region (AgNOR) and proliferating cell nuclear antigen (PCNA). Statistically significant differences found in expression of proliferative markers between most of them. Study of proliferative markers help in the proper diagnosis of different breast lesions which lies in the grey zone on routine histopathology.

Early detection of oral cancer: PAP and AgNOR staining in brush biopsies

Aim:The aim of this study was to determine the diagnostic accuracy of routine Papanicolaou stain (PAP) and Silver stained Nucleolar Organizer Regions (AgNOR) staining in brush biopsies taken from suspected oral lesions for early detection of oral cancer.Materials and Methods:Brush biopsies were collected from macroscopically suspicious lesions of the oral cavity of 34 patients and 10 normal-aged and sex-matched controls. The numbers of AgNORs were counted in 100 squamous epithelial cell nuclei per slide after silver staining of the smears (Ploton’s one-step method).Results:Sensitivity and specificity of PAP analysis in the oral smears for detection of oral cancer and normal cells was 91.176% and 100%. The positive and negative prediction values were 100% and 76.92%, respectively. Sensitivity and specificity of AgNOR analysis in the oral smears for detection of oral cancer and normal cells was 100%. The positive and negative prediction values were 100% each.Conclusion:Based on the above facts, we conclude that brush biopsy in conjunction with AgNOR staining is an easily practicable, non-invasive, safe and accurate screening method for the detection of macroscopically suspicious oral cancerous lesions. Because of its simple technique and high reliability for cellular proliferation, AgNOR staining in brush smears can be used as an adjunct to other routine cytological diagnoses for the early detection of oral cancer. However, further investigations with more number of study samples will be needed to establish this correlation beyond doubt.

Correlation Between Argyrophilic Nucleolar Organizer Region Staining and Brain Tumor Classification and Grading

ABSTRACTDistinctions between benign and malignant tumors are less evident in the central nervous system than in other tissues. Since the level of cell proliferation is an important feature in tumor grading, we applied AgNOR in 50 cases of brain tumors with different grades and histological origins in order to check its efficiency in discriminating between benign and malignant cases. We found significant differences between the means of grade I (1.76) and grade IV (2.46) tumors. No significant differences were observed considering the same grading with distinct histological types or age of patients, reinforcing the efficiency of AgNOR.

Chromosomes of Cichlasoma trimaculatum (male), Heros managuense (female) and their hybrid offspring

AbstractThe F1 hybrid offspring of the distant hybridization between Cichlasoma trimaculatum (male) and Heros managuense (female) were successfully obtained through artificial fertilization, and the chromosome specimen of kidney cells of the two parents and their offspring were prepared using a low colchicine concentration air drying method, Howell and Black's (1980) silver–nucleolar organizer region (Ag–NOR) staining method and Sumner's (1972) C-band staining method. The karyotypes, Ag–NORs and C-bands of C. trimaculatum, H. managuense and their offspring were observed. The results showed that the diploid numbers of the two parents and the F1 hybrid offspring were all 2n=48. For C. trimaculatum, the karyotype formula was 2n=2m+8sm+26st+12t, NF=58. Two Ag–NORs were seen on the tips of the short arm of chromosome st7, and the entire chromosomes of st9 and st13 and the centromeres of the other chromosomes had positive C-bands. For H. managuense, the karyotype formula was 2n=2m+6sm+28st+12t, NF=56. Two Ag–NORs were located on the tips of the short arm of chromosome sm2 and positive C-bands were found in the centromere of all chromosomes. In the F1 hybrid offspring, the chromosome formula was 2n=2m+8sm+30st+8t, NF=58. Two Ag–NORs were seen on the tips of the short arm of chromosome sm2; all chromosomes presented positive C-bands in the centromere. No heteromorphic sex chromosome was found. After comparison with the two parents, the F1 hybrid offspring was suggested to be the filial generation of the two hybrid parents rather than the gynogenesis of H. managuense induced by heterogeneous sperm of C. trimaculatum.

Correlation between the Histopathological Diagnosis by AgNOR Count and AgNOR Area in Canine Mammary Tumors

Mammary tumors are the most common type of tumor in female dogs. The histopathological diagnosis is usually made by a hematoxylin-eosin (HE) staining of the tumor, which then requires a pathologist's judgment for assessment of malignancy. The purpose of this study was to investigate an alternative silver staining of some argyrophilic nucleolar organizer regions (AgNOR) for improving the diagnostic accuracy with mammary tumors. There is a correlation between the histopathological diagnosis by AgNOR count and AgNOR area in canine mammary tumors. Seventy-three canine mammary tumors from 33 female dogs. The AgNOR staining was evaluated retrospectively in 73 canine mammary tumors with a parallel HE staining as a "Gold Standard." Both a quantitative manual counting method and a qualitative computerized morphometric method were tested. The result from both methods indicated a clinically relevant difference in the mean values of the AgNOR in the following 4 categories: malignant, benign, hyperplastic, and normal mammary tissue. The counting method was superior, with 89% of the cases given a correct diagnosis of a malignant or a nonmalignant canine mammary tumor. The 2 methods were then compared to test their ability to classify the tumors correctly. Again, the counting method was the most reliable method, with a sensitivity of 80% and a specificity of 76% when the upper 50% of the AgNOR counts were presumed malignant. The results indicated that an AgNOR test could be an aid to pathologists as a prognostic indicator or to assist them in deciding between a benign or a malignant diagnosis in questionable cases.

Oxidant-induced decrease of the expression of nucleolar organizer regions in pig lymphocytes can be useful for monitoring the cellular effects of oxidative stress

The technique of silver staining of nucleolar organizer regions (AgNORs) was chosen to estimate the transcriptionally active metaphase and interphase nucleolar organizer regions (NORs) in pig peripheral blood lymphocytes exposed to oxidative agents in vitro. The quantitative analysis of AgNORs was performed by using the counting method and the morphometric method. We found that hydrogen peroxide and 2,2′-azobis-(2-amidinopropane)-dihydrochloride (AAPH) induced a concentration-dependent decrease in NORs activity – in the case of metaphase the NORs activity was exclusively seen on chromosome pairs 8 – which can be considered as another estimate of cellular oxidative stress. Moreover, biomarkers of cyto- and genotoxicity, such as the percentage of apoptotic and necrotic cells, the nuclear division index (NDI) and formation of micronuclei (MN) were used to measure harmful effects provoked by the agents tested.

The diagnostic and prognostic implications of silver-binding nucleolar organizer regions in periodontal lesions

The periodontal lesions with cellular proliferation can be assessed by various methods. One of the most recent methods to determine the proliferative activity is silver-staining nucleolar organizer region (AgNOR) staining. The purpose of the present study was to evaluate, if AgNOR count can act as a proliferative marker and can aid in the diagnosis and prognosis of periodontal lesions. For this study, subjects with healthy gingival status, non-neoplastic lesions, neoplastic lesions, and plaque-induced gingivitis were included. Following the provisional diagnosis of clinical entity, biopsies were taken from the respective selected sites for histopathological diagnosis. In plaque-induced gingivitis cases, a second biopsy was taken from the selected sites 3 weeks following scaling. After histological confirmation, one more section was prepared, which was subjected to AgNOR staining, and AgNOR numbers were counted by individual and cluster counts and statistically analyzed. Results showed the highest AgNOR count in neoplastic lesions. Non-neoplastic lesions showed a higher AgNOR count as compared to clinically healthy gingiva. Plaque-induced gingivitis showed a considerable reduction in AgNOR count after treatment. Results of this study confirmed that AgNOR count reflects the cellular proliferation and has a limited diagnostic value. However, the prognostic value of AgNOR for periodontal lesions is dependable.

Silver staining of nucleolar organizer regions in prostatic lesions

HistopathologyVolume 21, Issue 1 p. 98-98 Silver staining of nucleolar organizer regions in prostatic lesions M. Ghazizadeh, M. Ghazizadeh Central Institute for Electron Microscopic Researches, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113, JapanSearch for more papers by this author M. Ghazizadeh, M. Ghazizadeh Central Institute for Electron Microscopic Researches, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113, JapanSearch for more papers by this author First published: July 1992 https://doi.org/10.1111/j.1365-2559.1992.tb00357.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue1July 1992Pages 98-98 RelatedInformation

X-Y-autosome translocation, chromosome compaction, NOR expression and heterochromatin insulation in the Scarabaeid beetle Dynastes hercules hercules

The karyotype of the giant beetle Dynastes hercules hercules is composed of only 16 autosomes and large sex chromosomes. Meiotic studies in the males showed that a large part of the sex chromosomes undergo synapsis at pachynema similarly to autosomes, demonstrating that both derived from an autosome-gonosome translocation. Therefore, karyotype formula is 18,neoXY. The heterochromatisation of the neoX short arm at pachynema indicates that it corresponds to the ancestral X. It carries the nucleolar organizer region (NOR) in its proximal part, which is undercondensed, especially in male mitotic and meiotic cells. In female mitotic cells, both NOR staining and undercondensation were more difficult to observe in the neoX short arms. In somatic interphase nuclei, NOR expression strongly varies with the sex. Two separated compact groups of silver dots were observed in female nuclei, while a single dispersed and large group of silver deposit exists in the males. Both the lower condensation and the higher NOR expression of the single neoX of the males, compared to each of the two neoXs of the females, is interpreted to be a consequence of dosage compensation, a mechanism not yet described in Coleoptera. In mammals as well as in Coleoptera, the carriers of gonosome-autosome translocations not exhibiting deleterious phenotypes show constitutive heterochromatin at the autosome-gonosome junction. Thus, heterochromatin may play an important universal role by clearly separating chromosome segments with different regulations of gene expression, such as inactivation or dosage compensation of the X chromosome on the one side and a conventional autosomal structure on the other side.