Effect of Hydroxyapatite Nanoparticles on the Growth Potential of Hepatoma Cells in Nude Mice.

AIM: To evaluate the activity of hydroxyapatite (HAP) nanoparticles against the proliferation of hepatoma cells. METHODS: HAP nanoparticles were prepared by homogeneous precipitation. The size distribution and morphology of these nanoparticles were determined by laser particle analysis and transmission electron microscopy, respectively. Xenograft tumor models of human hepatoma cells (Bel-7402) implanted in nude mice under the right scruff skin were established and divided into two groups: treatment and control. Once the xenograft tumor grew to a diameter of 0.8 cm, 0.2 ml HAP nanoparticle suspension was injected into the tumor every day for 2 weeks. The long and short diameters of the tumors were measured before and after HAP injection, and the inhibition rate of tumor growth was calculated. Paraffin tissue sections were prepared from xenograft tumors treated as above for 2 weeks, histologically stained for DNA and agyrophilic nucleolar organizer region (AgNORs), and immuno-histologically stained for proliferating cell nuclear antigens (PCNAs). The stained sections were examined by microscopy. Images of these sections were recorded and analyzed by image analysis system and relevant software for DNA content, AgNOR intensity, and PCNA expression in the nucleus, nucleoli, and hepatoma cells, respectively. RESULTS: The HAP nanoparticles were uniformly distributed, with a size of 44.6 nm to 86.8 nm. Upon the local injection of the tumor with the HAP nanoparticles, the average volumes of the tumors were significantly reduced compared with those of the control group, which had a tumor inhibition rate of 51.32%. The DNA content, AgNOR intensity, and PCNA expression in the hepatoma cells were all significantly reduced (P < 0.01) compared with those in the control group. CONCLUSION: HAP nanoparticles inhibit the proliferation of hepatoma cells in vivo.

Ellagic Acid-Changed Epigenome of Ribosomal Genes and Condensed RPA194-Positive Regions of Nucleoli in Tumour Cells.

We studied the effect of ellagic acid (EA) on the morphology of nucleoli and on the pattern of major proteins of the nucleolus. After EA treatment of HeLa cells, we observed condensation of nucleoli as documented by the pattern of argyrophilic nucleolar organizer regions (AgNORs). EA also induced condensation of RPA194-positive nucleolar regions, but no morphological changes were observed in nucleolar compartments positive for UBF1/2 proteins or fibrillarin. Studied morphological changes induced by EA were compared with the morphology of control, non-treated cells and with pronounced condensation of all nucleolar domains caused by actinomycin D (ACT-D) treatment. Similarly as ACT-D, but in a lesser extent, EA induced an increased number of 53BP1-positive DNA lesions. However, the main marker of DNA lesions, γH2AX, was not accumulated in body-like nuclear structures. An increased level of γH2AX was found by immunofluorescence and Western blots only after EA treatment. Intriguingly, the levels of fibrillarin, UBF1/2 and γH2AX were increased at the promoters of ribosomal genes, while 53BP1 and CARM1 levels were decreased by EA treatment at these genomic regions. In the entire genome, EA reduced H3R17 dimethylation. Taken together, ellagic acid is capable of significantly changing the nucleolar morphology and protein levels inside the nucleolus.

[Effect of peptide bioregulator and cobalt ions on the activity of NORs and associations of acrocentric chromosomes in lymphocytes of patients with hypertrophic cardiomyopathy and their relatives].

The influence of peptide bioregulator - Livagen (Lys-Glu-Asp-Ala) separately and combined with cobalt ions, on the activity of nucleolar organizer regions (NORs) and frequency of associations of acrocentric chromosomes in lymphocytes from patients with hypertrophic cardiomyopathy (HCM) and their relatives has been studied. It is shown that combined action of Livagen and cobalt ions increases the frequency of large-sized scoring 2 NORs in both, patients and their relatives. Significant was also the influence of the studied compounds on associative activity of acrocsentric chromosomes that was expressed in sharp increase of this indicator in both studied groups. In this case more effective was the action of Livagen and cobalt ions. As activity of NOR, also the frequency of associations of acrocentric chromosomes is dependent of quality of acrocentric chromosome stalk condensation, we conclude, that by influence of Livagen and cobalt ions on the lymphocytes of HCM patients and their relatives, occurs decondensation of heterochromatinized chromatin. This may be release condition during condensation of inactivated genes in the studied groups of individuals. Our data are important because it provides new information about protective effect of Livagen and Livagen+Cobalt ions on the lymphocytes of HCM patients and their relatives and may lead to the development of a therapeutic treatment.

Antiproliferative efficacy of hesperetin (citrus flavanoid) in 1,2-dimethylhydrazine-induced colon cancer.

Cancer is the second leading cause of death worldwide and is increasing at an alarming rate. The present study was to evaluate the antiproliferative effects of hesperetin, a flavonoid commonly found in many herbal medicines and foods, on aberrant crypt foci (ACF), argyrophylic nucleolar organizer regions (AgNORs) and proliferating cell nuclear antigen (PCNA) in 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. Rats were given subcutaneous injections of DMH (20 mg/kg body weight) weekly for 15 weeks to induce carcinogenesis, and hesperetin was administered orally at the dose of 20 mg/kg body weight. DMH exposure alone produced a high incidence of ACF and showed positive staining for PCNA and AgNORs in colonic tissues. Supplementation with hesperetin lowered the PCNA labeling index and suppressed the formation of ACF in the rats with colon cancer. These results clearly reveal that dietary hesperetin possesses antiproliferative ability against chemically induced colon tumourigenesis.

Exfoliative cytological assessment of apparently normal buccal mucosa among quid chewers using argyrophilic nucleolar organizer region counts and Papanicolaou staining.

OBJECTIVE: Quid chewing is associated with an increased risk of oral cancer. This study aims to analyze argyrophilic nucleolar organizer region (AgNOR) counts along with Papanicolaou (PAP) staining in exfoliative smears of quid chewers and non-chewers to correlate quid chewing habits with possible early cytological changes in apparently normal buccal mucosa. STUDY DESIGN: Exfoliative smears were obtained from normal buccal mucosa of 30 male quid chewers and non-chewers. The smears were stained using the AgNOR silver staining technique to evaluate the proliferative activity and PAP for cytological appearance. RESULTS: Statistically higher AgNOR counts were observed in chewers as compared to non-chewers. The difference in the mean percentage of nuclei having ≥5 AgNORs in both groups was statistically significant (p = 0.001). In chewers, PAP showed 77% with class I and the remaining 23% were class II, while the non-chewers showed only class I cytology. AgNOR counts between chewers and non-chewers having class I cytological appearance demonstrated a greater mean AgNOR count in chewers (p = 0.0001). CONCLUSION: Quid chewing seems to have a definite role in promoting proliferative activity of apparently normal buccal mucosal cells. Exfoliative cytological assessment of a combination of AgNOR counts and PAP has the potential for prediction of early quid-associated cellular changes before the appearance of clinical premalignant and malignant lesions.

[Inhibitory effects of doxycycline on argyrophilic nucleolar organizing regions and a-smooth muscle actin expression in proliferative bovine corneal myofibroblasts in vitro].

OBJECTIVE: To investigate the effect of doxycycline on the nucleolar organizing regions and a-smooth muscle actin expression in bovine corneal myofibroblasts in vitro and assess its contribution to ocular surface repair mechanisms. METHODS: Cell culture and identification: bovine corneal fibroblasts were cultured after the stroma was incubated in 1.0 and 2.0 g/L type I collagenase in two stages.Isolated cells were plated at mantaryay culture flask in 10% of BSA RPMI-1640. Vimentin and alpha-smooth muscle actin (α-SMA) organization were evaluated by immunocytochemistry. The cells staining positive for Vimentin and α-SMA indicated the presence of corneal myofibroblasts. Bovine corneal myofibroblasts were treated with different concentrations of doxycycline (10, 20, 40, 60, 80 mg/L) , a bland control group and the dexamethasone group (120 mg/L) were set up, each group had 30 cases. The argyrophilic nucleolar organizing regions (AgNOR) staining and the immunohistochemistry for α-SMA were performed when the cells were treated for 24 hours and 48 hours. The AgNOR count (Ag-c), AgNOR area (Ag-a) and the expression of α-SMA in the bovine corneal myofibroblasts among each experiment group and control group were compared using one-way ANOVA, further pairwise comparisons using Independent-Samples t test. RESULTS: Cell culture techniques were successfully used to establish a method for the isolation and culture of bovine corneal myofibroblasts. Microscopic examination and immunohistochemical staining confirmed that the cells cultured were bovine corneal myofibroblasts. The Ag-c and Ag-a of bovine corneal myofibroblasts progressively decreased as the concentrations of doxycycline was increase. 24 h:bland control group Ag-c was 6.40 ± 0.6, 60 mg/L doxycycline group Ag-c was 2.23 ± 0.43;bland control group Ag-a was (34.80 ± 2.36) µm(2), 60 mg/L doxycycline hormone group Ag-a was (19.91 ± 2.15) µm(2). 48 h: bland control group Ag-c was 7.27 ± 0.6,60 mg/L doxycycline hormone group Ag-c was 2.80 ± 0.76, bland control group Ag-a was (36.27 ± 1.99) µm(2), 60 mg/L doxycycline group Ag-a was (13.75 ± 2.09) µm(2). The differences were statistically significant: in the same time intervention (FAg-c 24 h = 252.55, FAg-a 24 h = 202.16, P < 0.05, FAg-c 48 h = 169.38, FAg-a 48 h = 853.23, P < 0.05), in the same concentrations intervention (tAg-c = 6.98, tAg-a = 11.62, P < 0.05). And 60 mg/L of doxycycline had an obviously inhibitory action as 120 mg/L dexamethasone in the same treated hours (dexamethasone group Ag-a 24 h = 30.56 ± 3.66, dexamethasone group Ag-a 48 h = 28.35 ± 1.23 ),the differences were not statistically significant (tAg-a 24h = 1.182, P = 0.242,tAg-a 48 h = 0.21, P = 0.832). As the concentrations investigated, doxycycline can inhibit the expression of α-SMA in the bovine corneal myofibroblasts (189.90 ± 7.48, 140.20 ± 7.79, 113.20 ± 8.98, 98.00 ± 3.50, 85.50 ± 4.99), the difference was statistically significant (F = 761.79, P = 0.00). While dexamethasone had no significant role in the expression of α-SMA (bland control group was 225.10 ± 6.74, the dexamethasone group was 228.50 ± 7.12), and the statistically difference was not obvious (t = 1.096, P = 0.287). CONCLUSIONS: As the concentrations of doxycycline was increased from 10 mg/L to 80 mg/L, the AgNOR count and AgNOR area of bovine corneal myofibroblasts can be significantly reduced in vitro. Compared with dexamethasone, doxycycline significantly suppressed the expression of α-SMA in bovine corneal myofibroblasts in a dose-dependent positive trend.

[Deheterochromatinization of the chromatin in old age induced by oligopeptide bioregulator (Lys-Glu-Asp-Pro)].

In this work is presented the data on the variability of the functional characteristics of the chromosomes in the cells exposed by oligopeptide bioregulator - Prostamax from old individuals (75-86 years). Evaluated: the frequency of sister chromatid exchanges (SCE); Ag-positive NORs (in associations and nonassociations), as well as the variability of the structural C-pericentromeric heterochromatin. Prostamax changed the chromosomal parameters: 1) increased the frequency of SCE to 12,0±0,28 exchange in per cell (in intact cells - 5,9±0,2); 2) increased the frequency of Ag-positive NORs to 2.5 per cell (in intact cells - 0.95) 3) reduced in the frequency of large segments of the options from the pericentromeric heterochromatin for the 1st and 9th chromosomes. Comparison of the results indicates the ability of Prostamax to decondensation, deheterchromatinization the chromatin during aging, and thus release by heterochromatinization repressed genes. On the other hand, the data obtained in this work suggest that the basis for the protective action of Prostamax its modifying effect on chromatin.

Effects of aluminum on nucleoli in root tip cells and selected physiological and biochemical characters in Allium cepa var. agrogarum L.

BACKGROUND: Increased Al concentration causes reduction of mitotic activity, induction of nucleolar alteration, increase of the production of ROS and alteration of several antioxidant enzyme activities in plant cells. Allium cepa is an excellent plant and a useful biomarker for environmental monitoring. Limited information is available about the effects of Al on nucleoli, antioxidant enzyme system, contents of MDA and soluble protein in A. cepa. Therefore, we carried out the investigation in order to better understand the effects of Al on the growth, nucleoli in root tip cells and selected physiological and biochemical characters. RESULTS: The results showed that the root growth exposed to 50 µM Al was inhibited significantly. 50 µM Al could induce some particles of argyrophilic proteins scattered in the nuclei and extruded from the nucleoli into the cytoplasm. The nucleolus did not disaggregate normally and still remained its characteristic structure during metaphase. Nucleolar reconstruction was inhibited. 50 µM Al induced high activities of SOD and POD in leaves and roots significantly (P < 0.05) when compared with control, whereas the level of CAT was low significantly (P < 0.05). At 50 µM Al the content of MDA in leaves was high significantly (P < 0.05) at 9(th) day and in roots increased (P < 0.05) with prolonging the treatment time during 6-12 days. The soluble protein content in leaves treated with 50 µM Al was high significantly (P < 0.05) at 6(th) day and increased with prolonging the treatment time. CONCLUSIONS: We suggest that variations in nucleoli and the alterations of antioxidant enzyme activities, MDA and soluble protein contents in Allium cepa can serve as useful biomarkers, which can provide valuable information for monitoring and forecasting effects of exposure to Al in real scenarios conditions. Among the antioxidant enzymes SOD and POD appear to play a key role in the antioxidant defense mechanism under Al toxicity condition. Data from MDA concentration show that Al indirectly produces superoxide radicals, resulting in increased lipid peroxidative products and oxidative stress.

Leukocyte Nucleolus and Anisakis pegreffii-When Falling Apart Means Falling in Place.

The view of the nucleolus as a mere ribosomal factory has been recently expanded, highlighting its essential role in immune and stress-related signalling and orchestrating. It has been shown that the nucleolus structure, formed around nucleolus organiser regions (NORs) and attributed Cajal bodies, is prone to disassembly and reassembly correlated to various physiological and pathological stimuli. To evaluate the effect of parasite stimulus on the structure of the leukocyte nucleolus, we exposed rat peripheral blood mononuclear cells (PBMC) to the crude extract of the nematode A. pegreffii (Anisakidae), and compared the observed changes to the effect of control (RPMI-1640 media), immunosuppressive (MPA) and immunostimulant treatment (bacterial lipopolysaccharide (LPS) and viral analogue polyinosinic:polycytidylic acid (poly I:C)) by confocal microscopy. Poly I:C triggered the most accentuated changes such as nucleolar fragmentation and structural unravelling, LPS induced nucleolus thickening reminiscent of cell activation, while MPA induced disassembly of dense fibrillar and granular components. A. pegreffii crude extract triggered nucleolar segregation, expectedly more enhanced in treatment with a higher dose. This is the first evidence that leukocyte nucleoli already undergo structural changes 12 h post-parasitic stimuli, although these are likely to subside after successful cell activation.

Analysis of cell cycle phases and proliferative capacity in mice bearing melanoma maintained on different dietary proteins.

BACKGROUND: Diet seems to represent, directly or indirectly, 35% of all cancer reports. In this study, the influence of dietary protein on the growth of melanoma B16F10 was evaluated through analyses of cell cycle phases and proliferative capacity. METHODS: Flow cytometry and argyrophilic nucleolar organizer regions (AgNORs) technique were applied in mice bearing B16F10 melanoma cells fed on different dietary proteins. All data were submitted to statistical analyses. RESULTS: The G0/G1 phase increased for the animal groups fed bovine collagen hydrolysate (BCH) or BCH-P1 + whey protein isolate (WPI), compared with mice receiving only WPI, for all dietary groups treated and nontreated with paclitaxel. Mice that received BCH + WPI treated with paclitaxel showed the highest percentage of apoptosis compared with WPI group. AgNORs, total nucleolar organizer regions (NORs)/cells and dot number/cell for all dietary protein groups nontreated with paclitaxel were higher than for the WPI. The only two dietary protein groups treated with paclitaxel that presented higher total NORs and dot number/cell than the WPI group were BCH + WPI and BCH-P1 + WPI. CONCLUSIONS: A significantly lower proliferative capacity and larger number of cells in the G0/G1 phase were observed for the dietary protein groups combining the two collagen hydrolysates, BCH or BCH-P1 with WPI, treated with paclitaxel.

Cadmium induction of lipid peroxidation and effects on root tip cells and antioxidant enzyme activities in Vicia faba L.

The effects of different concentrations (1-50 microM) of Cd on root growth, cell division and nucleoli in root tip cells, protective enzyme activities and lipid peroxidation in Vicia faba were investigated in order to better understand the processes of Cd-induced senescence. The results indicated that lower concentration of Cd (1 microM) had no obviously influence on the root growth during 24-48 h treatment, but higher concentrations (5-50 microM) inhibited significantly after 48 and 72 h. The mitotic index decreased with increasing of Cd concentration and duration of treatment except for the group exposed to 1 microM Cd. Cd induced c-mitosis, chromosome bridges, chromosome stickiness and lagging chromosomes. The rate of aberrant dividing cells increased with prolonging duration of treatment and increasing of Cd concentration. On nucleolus, some particulates containing the argyrophilic proteins were extruded from the nucleus into the cytoplasm in the cells stressed by Cd and some were scattered in the nucleus. After the treatment with Cd (10 microM Cd, 48 h), the nucleolus did not disaggregate normally and still remain its characteristic structure during metaphase and the particles of similar silver-stained materials were localized on chromosomes. In leaves, Catalase (CAT) activity declined but Peroxidase (POD) activity increased with increasing of the duration of treatment. In roots, CAT activity increased with increasing of the duration of treatment, POD activity increased during early days and then declined. Superoxide dismutase (SOD) activity showed an upward trend with increasing of the duration of treatment after 3 and 6 days, then declined both in leaves and roots (9 days). SOD and POD had highest activities at 50 microM Cd in leaves. CAT activity was lowest at 50 microM Cd. Malondialdehyde (MDA) content increased with the increasing of Cd concentrations and duration of treatment in leaves. In roots, MDA content showed an upward trend with increasing of the duration of treatment at early time and then declined.

[Cytogenetic effects of cholinotropic preparations mixture on Chironomus plumosus (Diptera) larvae in vivo].

Morphometric analysis of changes in nucleolar organizer (NO), Balbiani rings (BR)--BR(B), BR(1G), BR(2G) and chromosome I arm B puff activities, and in chromosome compactness of Chironomus plumosus (Diptera) polytene chromosomes was carried out in acute period under separate and combined influence of atropine and pilocarpine. Supression effect of cholinotropic preparations mixture was revealed. Suppression of NO activity with atropine concentration increase in the mixture served as criterion of toxicity.

Quantitative analysis of AgNOR counts and pap stain in exfoliative cytology specimens of oral mucosa in bidi smokers and nonsmokers.

Background: Bidi smoking is a serious health hazard which is common throughout South Asia and parts of the Middle East. It has been strongly implicated to various benign and malignant lesions of oral cavity and oropharynx. These tobacco-filled leaves deliver more than three times the amount of nicotine, carbon monoxide, and tar as cigarettes which exert injurious effects on cells reflected in terms of accelerated proliferative activity in normal oral mucosal cells. Aim: This study aimed to compare the exfoliated cells from the oral mucosa of bidi smokers and nonsmokers, with emphasis on proliferative activity. Materials and Methods: Exfoliative smears were obtained from the oral mucosa of forty participants (twenty nonsmokers and twenty smokers) with age group ranging from 30-80 years, in and around Barwala (Haryana). The cytologic smears were evaluated using Papanicolaou (PAP) stain and AgNOR in order to evaluate the presence of cytological alterations suggestive of inflammation, dysplasia, keratinization, and proliferative activity of epithelial cells. Only PAP Class I and Class II smears were observed. Results: Comparison of the mean number of AgNORs showed a significant difference between nonsmokers and smokers. Inflammatory alterations were found in 70% of smokers and 55% of nonsmokers. A significant difference in proliferative activity was observed between smokers and nonsmokers classified as PAP Class II. Conclusion: A significant difference of AgNORs/nucleus was observed between bidi smokers and nonsmokers.

RésuméContexte: Bidi fumeurs est un grave danger pour la santé qui est commune dans toute l'Asie du Sud et certaines parties du Moyen-Orient. Il a été fortement impliqué dans diverses lésions bénignes et malignes de la cavité buccale et l'oropharynx. Ces feuilles de tabac offrent plus de trois fois la quantité de nicotine, monoxyde de carbone et de goudron que les cigarettes qui exercent des effets préjudiciables sur les cellules reflétés sous la forme d' une accélération de l'activité proliférative des cellules de la muqueuse buccale normale. Objectif: Cette étude visait à comparer les cellules exfoliées de la muqueuse orale des bidis fumeurs et non fumeurs, avec l'accent sur l'activité proliférative. Matériels et méthodes: frottis Exfoliative ont été obtenus à partir de la muqueuse orale de 40 participants (20 non-fumeurs et fumeurs) avec 20 Groupe d'âge allant de 30-80 ans, dans et autour de Barwala (Haryana). Le frottis cytologique ont été évalués à l'aide de la coloration de Papanicolaou (PAP) et d'AgNOR afin d'évaluer la présence d' altérations cytologiques évocateurs d'infl ammation, dysplasie, la kératinisation, et l'activité proliférative des cellules épithéliales. PAP uniquement les catégories I et II de Papanicolaou n'a été observé. Résultats: comparaison du nombre moyen d'AgNORs ont montré une différence entre les non-fumeurs et les fumeurs. Des modifications ont été trouvés infl ammatory dans 70% des fumeurs et 55% des non-fumeurs. Une différence dans l'activité proliférative a été observée entre les fumeurs et les non-fumeurs PAP, le niveau d'emploi de la classe II. Conclusion: une différence de AgNORs/noyau a été observée entre fumeurs et non-fumeurs bidi. Mots-clés: AgNOR, frottis exfoliative, les fumeurs.

Initiation of nucleolar assembly is independent of RNA polymerase I transcription.

This report examines the distribution of an RNA polymerase I transcription factor (upstream binding factor; UBF), pre-rRNA processing factors (nucleolin and fibrillarin), and pre-rRNAs throughout mitosis and postmitotic nucleologenesis in HeLa cells. The results demonstrate that nucleolin, fibrillarin, and pre-rRNAs synthesized at G2/M phase of the previous cell cycle are directly recruited to UBF-associated nucleolar organizer regions (NORs) early in telophase before chromosome decondensation. Unlike the fusion of prenucleolar bodies to the nucleoli, this early recruitment of processing factors and pre-rRNAs is independent of RNA polymerase I transcription. In the absence of polymerase I transcription, the initial localization of nucleolin, fibrillarin, and pre-rRNAs to UBF-associated NORs generates segregated mininucleoli that are similar to the larger ones observed in interphase cells grown under the same conditions. Pre-rRNAs are juxtaposed to UBF-nucleolin-fibrillarin caps that may represent the segregated nucleoli observed by electron microscopy. These findings lead to a revised model of nucleologenesis. We propose that nucleolar formation at the end of mitosis results from direct recruitment of processing factors and pre-rRNAs to UBF-associated NORs before or at the onset of rDNA transcription. This is followed by fusion of prepackaged prenucleolar bodies into the nucleolus. Pre-ribosomal ribonucleoproteins synthesized in the previous cell cycle may contribute to postmitotic nucleologenesis.

GC-rich heterochromatin in silver stained nucleolar organizer regions (NORs) fluoresces with Chromomycin A3 (CMA3) staining in three species of teleostean fishes (Pisces).

In a bid to ascertain the molecular architecture of the silver positive regions (NORs) in chromosomes of three species of fish, namely, Hemibagrus menoda (Hamilton), Sperata seenghala (Sykes) (Fam: Bagridae) and Mastacembelus armatus (Lacep6de) (Fam: Mastacembelidae), an additional staining methodology using a fluorochrome dye (Chromomycin A3) was deployed along with the AgNO3 technique. The nucleolar organizing regions (NORs) were located terminally at the shorter arms (Tp) of one pair of submetacentric chromosomes (No.3) in H. menoda (2n=58), at the longer arms (Tq) of one pair of submetacentric chromosomes (No.5) in S. seenghala (2n=50) and at the shorter arm (Tp) of one pair of homologous submetacentric chromosomes (No.6) in M. armatus (2n=48). Staining with Chromomycin A3 produced bright fluorescing zones in GC-rich heterochromatin of Ag-positive NORs. The results indicate a more general trend of existence of an overlapping region between NOR and GC-rich fluorescing zones, the active sites of rRNA genes (rDNA) in this primitive group of vertebrates although exceptions to this situation has been reported in a couple of extant fish species earlier. More data utilizing such combined methodologies are warranted to understand the structural organization of fish chromosomes more precisely.

NORs and their transcription competence during the cell cycle.

In human cells ribosomal genes are organized as clusters, NORs, situated on the short arms of acrocentric chromosomes. It was found that essential components of the RNA polymerase I transcription machinery, including UBF, can be detected on some NORs, termed "competent" NORs, during mitosis. The competent NORs are believed to be transcriptionally active during interphase. However, since individual NORs were not observed in the cell nucleus, their interphase status remains unclear. To address this problem, we detected the competent NORs by two commonly used methods, UBF immunofluorescence and silver staining, and combined them with FISH for visualization of rDNA and/or specific chromosomes. We found that the numbers of competent NORs on specific chromosomes were largely conserved in the subsequent cell cycles, with certain NOR-bearing homologues displaying a very stable pattern of competence. Importantly, those and only those NORs that were loaded with UBF incorporated bromo-uridine in metaphase after stimulation with roscovitine and in telophase, suggesting that competent and only competent NORs contain ribosomal genes transcriptionally active during interphase. Applying premature chromosome condensation with calyculin A, we visualized individual NORs in interphase cells, and found the same pattern of competence as observed in the mitotic chromosomes.

Norethindrone scatters silver-stained nucleolar organizer regions of Ishikawa cells.

We investigated the effects of sex steroids on silver-stained nucleolar organizer regions (Ag-NORs) and DNA/RNA kinetics in Ishikawa cells. Norethindrone and its isomer norethynodrel exclusively caused Ag-NORs to scatter in the nuclear matrix, from the nucleolus. No such effect occurred with the other sex steroids tested, including progestational, androgenic, and estrogenic compounds. Nuclear argyrophilic substances induced by norethindrone, as well as nucleolar ones, were neither DNA nor RNA but protein. Electron microscopy showed that norethindrone caused nucleolar segregation, in which the fibrillar components disappeared, and it produced islets, consisting of dense fibrillar materials, in the nucleoplasm. Ag-NORs observed on the fibrillar components in control nucleoli were translocated onto the dense fibrillar materials in the nucleoplasm. Although scattering was preferentially found in the cells synthesizing DNA, the scintillation assay of DNA/RNA kinetics suggested that scattering was related to the inhibition of RNA synthesis. These results imply that norethindrone preferentially interacts with intranucleolar DNA when its duplication is occurring and then interferes with rRNA synthesis. Scattering of Ag-NORs might not be caused by the hormonal activity of these agents but by a pharmacological effect derived from their molecular structures.

Ligands for peroxisome proliferator-activated receptors alpha and gamma inhibit chemically induced colitis and formation of aberrant crypt foci in rats.

The biological role of the peroxisome proliferator-activated receptors (PPARs) in various diseases, including inflammation and cancer, has been highlighted recently. Although PPARgamma ligands have been found to inhibit mammary carcinogenesis in rodents, the effects on colon tumorigenesis are controversial. In the present study, three different experiments were conducted to investigate the modifying effects of PPARs ligands (PPARalpha and PPARgamma) on colitis and an early phase of colitis-related colon carcinogenesis in male F344 rats. In the first experiment, gastric gavage of troglitazone (PPARgamma ligand, 10 or 100 mg/kg body weight) or bezafibrate (PPARalpha ligand, 10 or 100 mg/kg body weight) inhibited colitis induced by dextran sodium sulfate (DSS) and lowered trefoil factor-2 content in colonic mucosa. In the second experiment, dietary administration (0.01 or 0.05% in diet) of troglitazone and bezafibrate for 4 weeks significantly reduced azoxymethane (AOM, two weekly s.c. injections, 20 mg/kg body weight)-induced formation of aberrant crypts foci, which are precursor lesions for colon carcinoma. In the third experiment, dietary administration (0.01% in diet for 6 weeks) of pioglitazone (PPARgamma ligand), troglitazone, and bezafibrate effectively suppressed DSS/AOM-induced ACF. Administration of both ligands significantly reduced cell proliferation activity in colonic mucosa exposed to DSS and AOM. Our results suggest that synthetic PPARs ligands (PPARalpha and PPARgamma) can inhibit the early stages of colon tumorigenesis with or without colitis.

Are there any effects of chronic carbon monoxide exposure on argyrophilic nucleolar-organizing region-associated protein synthesis in rat myocardium?

The aims of the study are to detect whether there are any possible effects of chronic carbon monoxide (CO) exposure on the argyrophilic nucleolar-organizing region (AgNOR)-associated protein synthesis and evaluate any possible relationship between the amount of AgNOR protein and the level of myocardial injury also and between AgNOR and histopathological evaluation methods. Adult male albino Wistar rats (n = 18) were randomly divided into three groups (groups A, B, and C). Group A served as control, while groups B and C were rats exposed to CO gas chronically (1000 and 3000 ppm CO concentration with a flow rate of 4 L/min for 30 min/day for 7 days, respectively). Total AgNOR area/nuclear area (TAA/NA) and the mean AgNOR numbers for each myocyte nucleus were determined. There were significant differences among all groups for TAA/NA ratio. These differences were not significant for mean AgNOR numbers. According to the histopathological evaluation scores, there were significant differences between the groups. The differences were significant among the groups for loss of sarcomere pattern. A strong positive correlation between histopathological injury scores and TAA/NA ratio was found (Rsq = 0.48; p = 0.002), however, the correlation was not significant for mean AgNOR numbers (Rsq = 0.08; p = 0.25). In conclusion, TAA/NA ratio can be used as an indicator for obtaining information about the level of myocardial damage instead of histopathological evaluation scores.

Decreased argyrophilic nucleolar organiser region (AgNOR) expression in Purkinje cells: first signal of neuronal damage in sudden fetal and infant death.

AIMS: The nucleolus is an important cellular component involved in the biogenesis of the ribosome. This study was performed in order to validate the introduction of the argyrophilic nucleolar organiser region (AgNOR) stain technique, specific for the nucleoli detection, in neuropathological studies on sudden fetal and infant death. METHODS: In a wide set of fetuses and infants, aged from 27 gestational weeks to eight postnatal months and dead from both known and unknown causes, an in-depth neuropathological study usually applied at the Lino Rossi Research Center of the Milan University was implemented by the AgNOR method. RESULTS: Peculiar abnormalities of the nucleoli, as partial or total disruption above all in Purkinje cells (PCs), were exclusively found in victims of sudden fetal and infant death, and not in controls. The observed nucleolar alterations were frequently related to nicotine absorption in pregnancy. CONCLUSIONS: We conclude that these findings represent early hallmarks of PC degeneration, contributing to the pathophysiology of sudden perinatal death.