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.

Identification of novel markers that demarcate the nucleolus during severe stress and chemotherapeutic treatment

The nucleolus, the ribosomal factory of the cell, has emerged as a key player that regulates many aspects of cell biology. Several thousand proteins associate at least transiently with nucleoli, thereby generating a highly dynamic compartment with a protein profile which is sensitive to changes in cell physiology and pharmacological agents. Powerful tools that reliably demarcate the nucleoli are a prerequisite to measure their composition and activities. Previously, we developed quantitative methods to measure fluorescently labeled molecules in nucleoli. While these tools identify nucleoli under control and mild stress conditions, the accurate detection of nucleolar boundaries under harsh experimental conditions is complicated by the lack of appropriate markers for the nucleolar compartment. Using fluorescence microscopy we have now identified new marker proteins to detect nucleoli upon (a) severe stress and (b) drug treatments that trigger a pronounced reorganization of nucleoli. Our results demonstrate that nucleolin is an ideal marker to delimit nucleoli when cells are exposed to heat or oxidative stress. Furthermore, we show for the first time that cellular apoptosis susceptibility protein (CAS) and human antigen R protein (HuR) are excluded from nucleoli and can be employed to delimit these compartments under severe conditions that redistribute major nucleolar proteins. As proof-of-principle, we used these markers to demarcate nucleoli in cells treated with pharmacological compounds that disrupt the nucleolar organization. Furthermore, to gain new insights into the biology of the nucleolus, we applied our protocols and quantified stress- and drug-induced changes in nucleolar organization and function. Finally, we show that CAS, HuR and nucleolin not only identify nucleoli in optical sections, but are also suitable to demarcate the nucleolar border following 3D reconstruction. Taken together, our studies present novel marker proteins that delimit nucleoli with high confidence under a variety of experimental settings.

[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.

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.

[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.

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.

Nucleolar translocalization of GRA10 of Toxoplasma gondii transfectionally expressed in HeLa cells

Toxoplasma gondii GRA10 expressed as a GFP-GRA10 fusion protein in HeLa cells moved to the nucleoli within the nucleus rapidly and entirely. GRA10 was concentrated specifically in the dense fibrillar component of the nucleolus morphologically by the overlap of GFP-GRA10 transfection image with IFA images by monoclonal antibodies against GRA10 (Tg378), B23 (nucleophosmin) and C23 (nucleolin). The nucleolar translocalization of GRA10 was caused by a putative nucleolar localizing sequence (NoLS) of GRA10. Interaction of GRA10 with TATA-binding protein associated factor 1B (TAF1B) in the yeast two-hybrid technique was confirmed by GST pull-down assay and immunoprecipitation assay. GRA10 and TAF1B were also co-localized in the nucleolus after co-transfection. The nucleolar condensation of GRA10 was affected by actinomycin D. Expressed GFP-GRA10 was evenly distributed over the nucleoplasm and the nucleolar locations remained as hollows in the nucleoplasm under a low dose of actinomycin D. Nucleolar localizing and interacting of GRA10 with TAF1B suggested the participation of GRA10 in rRNA synthesis of host cells to favor the parasitism of T. gondii.

Proliferative activity in clinically healthy oral mucosa exposed to tobacco smoking and alcohol: a longitudinal study using the agNOR staining technique

OBJECTIVE

To evaluate cell proliferation in clinically healthy oral mucosa exposed to smoking and alcohol carcinogens over a period of 24 months using the AgNOR staining technique.

STUDY DESIGN

Sixty patients were initially evaluated: 17 were control individuals, 25 were smokers and 18 were smokers and alcohol drinkers. Fifty-two of these patients were reevaluated. Specimens for cytology were obtained from swabs of lower lip mucosa, border of the tongue and floor of the mouth and underwent AgNOR staining for evaluation of mean number and mean area of AgNOR dots per nucleus and percentage of nuclei with > 3 and > 5 AgNOR dots. Student t and Kruskal-Wallis tests were used to compare values obtained.

RESULTS

A statistically significant increase was found in mean number of AgNOR dots per nucleus in 2 groups. One group showed a tendency toward increase of these values. The results of the longitudinal evaluation (Kruskal-Wallis test) revealed a statistically significant difference in number and area of AgNOR dots in the cells of the lower lip.

CONCLUSION

The increase of the variables suggests that the longitudinal evaluation of changes in cell proliferation in individuals exposed to smoking and alcohol carcinogens may be a useful monitoring tool.

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.

Activity of nucleolar organizers in hepatocytes of rats with cirrhosis of the liver after treatment with bioactive preparations

The therapeutic efficiency of bioactive preparations of the liver and spleen in the treatment of experimental toxic cirrhosis of the liver is shown. Evaluation of the nucleolar organizer activity showed the highest efficiency of treatment with human fetal liver extract.

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.

Cleavage of nucleolin and AgNOR proteins during apoptosis induced by anticancer drugs in human salivary gland cells

BACKGROUND

To investigate the behavior of nuclear proteins in apoptosis induced by anticancer drugs in cultured human salivary gland (HSG) cells.

METHODS

Dynamic alternations of nucleolin and argyrophilic nucleolar organizer region (AgNOR) proteins in anticancer drug-induced apoptosis of HSG cells and in a cell-free apoptotic system were examined using Western blot analysis and immunocytochemical method.

RESULTS

The 110-kDa form of nucleolin and AgNOR protein decreased and the 80- and 95-kDa forms appeared during apoptosis in HSG cells and in a cell-free apoptotic system. In addition, the induction of DNA ladder formation coincided with the appearance of alternation of nucleolin and AgNOR proteins in a cell-free apoptosis. Nucleolin diffusely spread out into the nuclear material in the apoptotic body of HSG cells.

CONCLUSIONS

The present results indicate that alternations of nucleolin and AgNOR proteins are associated with the induction of DNA fragmentation and the final active phase of apoptosis induced by anticancer drugs in malignant salivary gland cells.

Neoplastic and preneoplastic lesions induced by melamine in rat urothelium are modulated by dietary polyunsaturated fatty acids

The modulatory effects of polyunsaturated fatty acids (PUFA) on urinary tract tumorigenesis of 275 Wistar rats were evaluated by treating animals with the tumorigenic agent melamine. Rats were fed with formulae containing 6% of 4 varieties of fats: fish oil enriched in n-3 PUFA (FO), corn oil enriched in n-6 (CO), olein containing mainly n-9 oleic acid (O), and 98% stearic acid (SA), the latter two being essential (EFA)-deficient inducers. Two commercially fed control groups with (CM) and without (C) melamine were used. Animals were autopsied at 22-25 and at 36-40 weeks. Hepatic fatty acids showed that O and SA groups were EFA-deficient. Simple well differentiated hyperplasias were significantly higher in the FO lot, whereas dysplasia was increased in the CO, O and SA lots. Most of the animals fed for 36-40 weeks with the three latter formulae developed the more severe lesions. Increased urothelial proliferation was more frequent in EFA-deficient rats. The apoptosis/mitosis ratio was higher in O, SA and CO fed animals with respect to FO and chow ones. Results show that dietary PUFA modulate differentially both normal and pre-neoplastic urothelial proliferation induced by melamine. FO, rich in n-3 fatty acids, showed a strong protective effect.

Quantification of silver-staining nucleolar organizer region in epithelial cells of tongue of mice after exposure to, or intake of, alcohol

The purpose of the current study was to evaluate the effect of alcohol on the proliferative activity of epithelial cells in the lingual mucosa of mice by means of silver-staining nucleolar organizer region (AgNOR) count and area measurements. Forty-eight CF1 mice were separated into three groups. The test groups were submitted to topical exposure to, or intake of, 40% (volume/volume) ethyl alcohol. Biopsy specimens were collected from the middle third of the dorsal tongue at 0, 6, and 12 months, and samples were stained according to the AgNOR technique. Mean number and mean area of AgNOR per nucleus were calculated for 50 basal layer cells and 50 intermediate layer cells. Increases in mean number and mean area of AgNOR per nucleus in intermediate cells were observed at 12 months in the alcohol intake group (P < .05). Results showed that intake of 40% alcohol increased epithelial cell proliferation in the dorsal surface of lingual mucosa.

[the effect of colonystimulating macrophage factor on activity of the nuclear organisers in central macrophages of the cultures of the bone marrow erythroblastic islands]

Erythroblastic islands of the bone marrow are morpho-functional units of erythropoiesis. The functional state of erythroblastic islands' cells of the bone marrow was for the first time defined by estimation of activity of the nuclear organisers of the central macrophages in the erythroblastic islands cultivated for 24 hrs in presence of various doses of the colony-stimulating macrophage factor. The findings indicate that increased doses of the colonystimulating macrophage factor was accompanied by a respective enhancement of the activity of nucleolar organisers in central macrophages of erythroblastic islands.

A short note on the nucleolar size and density in apoptotic leukemic granulocytic precursors (HL-60 cells)

The present study was undertaken to provide more information on the nucleolar size and density in mononuclear blastic granulocytic precursors represented by HL-60 cells the proliferation of which was blocked by photodynamic treatment (PDT) which induced apoptotic process without preceding terminal maturation. Both the nucleolar size and density did not change in apoptotic cells in comparison with controls. Thus, large and dense nucleoli in apoptotic cells are not necessarily related to the nucleolar biosynthetic or cell proliferation activity.

Early correction of cell cycle perturbations predicts the immunological response to therapy in HIV-infected patients

OBJECTIVE

To determine whether changes in the indices of HIV-associated cell cycle dysregulation (i.e., increased expression of cyclin B1 and abnormal nucleolar structure) may predict the level of immunological reconstitution in HIV-infected patients treated with highly active antiretroviral therapy (HAART).

METHODS

Cross-sectional and longitudinal analysis of viral load, CD4 T cell counts, cyclin B1 expression, and AgNOR number and area of distribution in 30 HIV-infected patients who were studied before and up to 6 months after initiation of HAART.

RESULTS

In HIV-infected individuals, the level of cell cycle dysregulation correlated with the type of response to HAART. While low levels of dysregulation were present in patients with complete (both virological and immunological) response to HAART, high levels were present in HAART-treated patients with limited CD4 T cell increases despite persistent viral suppression (immunological non-responders). Importantly, the level of correction of cell cycle dysregulation after 60 days of therapy predicted the level of immune reconstitution after 6 months.

CONCLUSION

These observations suggest that correction of cell cycle dysregulation predicts a good immunological response to HAART and that sequential analysis of cell cycle dysregulation might help to identify patients that could benefit from alternative, immune-based interventions in addition to standard HAART.

Effects of hyperthermia and differentiation on cultured Dunn osteosarcoma cells

We investigated the characteristics of morphology, DNA synthesis and argyrophilic nucleolar organizer regions (AgNORs) on murine Dunn osteosarcoma cells in response to heat (42 degrees C, 1 h) or dibutyryl cyclic adenosine 3',5'-monophosphate (Bt(2)cAMP). The cell morphology changes to a fibroblast-like appearance with long and thin protoplastic processes with the reduction of DNA synthesis by heat. It is closely similar to a response by Bt(2)cAMP. In the presence of 3 mM Bt(2)cAMP, the mean number of AgNORs was significantly decreased in 48 h compared with the untreated group. It was increased conversely by heat. Among these responsive cells, we can also find many cells stained without discrimination by the use of AgNORs staining. The present study provides a new clue to support differentiation of osteosarcoma cells from the viewpoint of hyperthermia in vitro.

Nucleoli in large (giant) bi- and multinucleate cells after apoptosis-inducing photodynamic treatment

The present experimental study was undertaken to provide information on nucleolar changes accompanying the apoptotic process in large or giant binucleate and multinucleate cells (LBMNCs). Such cells were present in a small but constant percentage in cultures of HL-60 cells. The apoptotic process was induced by photodynamic treatment (PDT) by means of 5-aminolaevulinic acid (ALA) as the precursor of the photosensitizer protoporphyrin IX and irradiation with broad spectrum blue light (BL). Nucleolar changes in LBMNCs were characterized by marked reduction or disappearance of silver stained particles representing AgNORs in nucleoli including the large ones. In addition, PDT also significantly reduced the number of nucleoli regardless of their size. These changes apparently reflected the decrease or cessation of nucleolar biosynthetic activities and resembled those which were previously observed in naturally maturing bone marrow megakaryocytes (Janoutová et al., 2001).

[Activity of nucleolar organizers in central macrophage culture of bone marrow erythroblastic islands]

The erythroblastic islands of the bone marrow are morphofunctional units of erythropoiesis. In this work the functional state of erythroblastic islands' cells of the bone marrow, for the first time, was defined by the estimation of the activity of the nucleolar organizers of central macrophages in the erythroblastic islands, cultivated during 24 and 48 hours with the presence of various doses of erythropoietin. The findings indicated that the increase in doses of erythropoietin was accompanied by the corresponding increase of the activity of nucleolar organizers in central macrophages of erythroblastic islands. The nucleolar organizers of central macrophages in cultures of erythroblastic islands responded to very small doses of erythropoietin by their activation.

[Assessment of the influence of chemotherapy on the nucleolar organizer regions (AgNORs) count in serous ovarian cancer cells]

OBJECTIVE

When planning treatment of ovarian cancer, the prognostic factors should be considered. One of them is the amount of nucleolar organizer regions (AgNORs) in cancer cells, which reflects proliferative activity of the tumor.

DESIGN

To estimate the influence of chemotherapy on the AgNORs count in serous ovarian cancer cells.

MATERIAL AND METHODS

26 women who underwent surgical procedure and then chemotherapy between 1998-2002 due to serous ovarian cancer were included into the study. During the initial surgery the cancer stage I was detected in 1 case, stage II in 2 cases, stage III in 12 cases, and stage IV in 11 cases. In all cases during second-look laparotomy, which was performed after 6 courses of chemotherapy (paclitaxel, cisplatinum), the persistent disease was found. In 17 out of 26 cases it was disseminated neoplasmatic disease. In all cases the specimens were prepared according to one-step AgNORs method described by Howell and Ploton. In cancer cells the mean number of AgNORs per nucleus (mAgNOR) and the mean percentage of nuclei with five or more AgNORs per nucleus (pAgNOR) were counted.

RESULTS

The mAgNOR and pAgNOR mean number before chemotherapy were respectively: 4, 22 +/- 0.94 and 35.62 +/- 19.90. After treatment the mAgNOR and pAgNOR were significantly lower, and the data were respectively: 3.67 +/- 0.91 and 24.15 +/- 19.53. In 4 cases (15.4%) the mAgNOR increased, in 7 cases (26.9%) the change was not significant, and in 15 cases (57.7%) the mAgNOR decreased. In 6 cases (23.1%) the pAgNOR increased, in 5 cases (19.2%) the change was not significant, and in 15 cases (57.7%) the pAgNOR decreased. We did not found any correlation between the tendency to change the number of AgNORs and staging, the amount of persistent neoplasmatic tissue, the range of primary surgery, as well as grading.

CONCLUSIONS

The number of AgNORs per nucleus in most cases of ovarian cancer after chemotherapy was lower. The tendency to change the number of AgNORs was not connected with staging as well as grading.

Micronuclei, nuclear lesions and interphase silver-stained nucleolar organizer regions (AgNORs) as cyto-genotoxicity indicators in Oreochromis niloticus exposed to textile mill effluent

In this study, cyto-genotoxic effects of a textile mill effluent on fish Oreochromis niloticus were investigated using the micronucleus (MN) test and methods to analyze interphase silver-stained nucleolar organizer regions (AgNORs). Fishes were exposed to three different concentrations of textile mill effluent (5, 10 and 20%(v/v)) for 3, 6 and 9 days. Cyclophosphamide (2mg/l) was used as a positive control. Micronucleus frequencies were examined in peripheral blood erythrocytes and gill cells. Nuclear abnormalities (NA) other than micronuclei such as binuclei, lobed nuclei, blebbed nuclei and notched nuclei were also evaluated in peripheral erythrocytes. Interphase AgNOR parameters were examined in epithelial cells obtained from the edge of caudal fins after 90 and 180min of exposure. As a result, dose-dependent increases in the frequencies of micronuclei and other NA in erythrocytes were observed. MN frequencies in gill cells also significantly increased, while the interphase AgNOR parameters in fin cells decreased, as a result of textile effluent and cylophosphamide treatments.

Post-initiation inhibition of MeIQx hepatocarcinogenesis in rats by cysteine

Rats were administered cysteine at a dose of 100 mg/kg b.w. 5 times per week after 2-amino-3, 8-dimethylimidazo [4,5-f] quinoxaline (MeIQx) treatment. Significant decrease in numbers and areas of glutathione S-transferase placental form (GST-P)-positive foci, putative preneoplastic lesions, and silver-stained nucleolar organizer regions were evident in the livers of rats treated with cysteine after MeIQx treatment. Morever, post-initiation stage cysteine treatment resulted in decreased hepatic insulin-like growth factor (IGF)-I mRNA expression. Thus post-initiation cysteine treatment may exert chemopreventive effect on MeIQx hepatocarcinogenesis.

Functional and structural rearrangements of salivary gland polytene chromosomes of Chironomus riparius Mg. (Diptera,Chironomidae) in response to freshly neutralized aluminium

Although recent work has shown that environmentally relevant concentrations of freshly neutralized aluminium (AI) are bioavailable and toxic to freshwater invertebrates, the genotoxicity of Al has not been examined. Here we show that freshly neutralized Al affects structure and function of the salivary gland polytene chromosomes of the ubiquitous chironomid larva Chironomus riparius over three generations. Exposure to 500 microg l-1 added Al for 24-25 days resulted in a significantly higher frequency of numerous somatic aberrations, while no structural aberrations were found in F1 controls and few in the second and third generation. Aberrations also included deletions of sections of chromosome G of C. riparius larvae as well as deletions of one or more Balbiani rings. Changes in functional activity included decreased activity of the Balbiani rings (BR), and an increase in the number of decondensed centromeres. The activity of the nucleolar organizer (NOR) significantly decreased in F1 chironomids exposed to Al, while in the F2 and F3 generations the NOR showed normal (high) activity. First generation chironomids were generally more susceptible to Al although no clear evidence of tolerance was apparent over three generations. The possible use of alterations in chironomid polytene chromosomes as biomarkers of trace metal pollution is discussed.

[NOR (nucleolar organizer region) activity in wheat species with different ploidy levels treated with phytohormones]

The effects of the phytohormones 6-benzylaminopurine (BAP) and 24-epibrassinolide (EB) on the nucleolar sizes in the interphase nuclei of root meristem were studied using the silver-staining procedure in wheat species with different ploidy levels (a polyploid series). In addition, the effects of the phytohormones on the cell mitotic activity in the roots of 5-day-old seedlings were studied. The higher the wheat species ploidy level, the higher its sensitivities to BAP and EB were. In diploid wheat, the maximum increase in the nucleolar organizing region (NOR) activity was observed after treatment with considerably higher phytohormone concentrations compared to tetra- and hexaploid wheat species. The phytohormone treatment increased both the sizes and the number of nucleoli in meristematic cells of seedling roots in all wheat species studied. It was assumed that the differences between the responses of wheat species with three different ploidy levels to different concentrations of phytohormones were related to their effects on the methylation/demethylation of cytosine residues in the rDNA promoter region.

Effects of Livagen peptide on chromatin activation in lymphocytes from old people

We studied the effects of the synthetic peptide Livagen on activity of ribosomal genes, denaturation parameters of heterochromatin, polymorphism of structural C-heterochromatin, and variability of facultative heterochromatin in lymphocytes from old people. Livagen induced activation of ribosomal genes, decondensation of pericentromeric structural heterochromatin, and release of genes repressed due to age-related condensation of euchromatic regions in chromosomes. Our results indicate that Livagen causes de-heterochromatinization (activation) of chromatin, which is realized via modification of heterochromatin and heterochromatinized regions in chromosomes from old people.

[Activity of the nucleolar organizers in cultured cells from the bone marrow erythroblastic islets]

The erythroblast islands of the bone marrow are the morphofunctional units of erythropoiesis. In this work, the functional state of erythroblast islands' cells of the bone marrow for the first time was defined by estimation of the activity of the nucleolar organizers of erythroid cells in the erythroblast islands cultivated during 24 and 48 hours in presence of various doses of erythropoietin. The findings indicated that an increase in doses of erythropoietin was accompanied by a corresponding increase of the activity of nucleolar organizers in erythrokaryocytes of erythroblast islands. The nucleolar organizers of erythroid cells in cultures of erythroblast islands responded with activation to very small doses of erythropoietin; besides, a proliferative response of erythrokaryocytes was observed after activation of the nucleolar organizers.

Genome restructuring in rye affects the expression, organization and disposition of homologous rDNA loci

The standard rye cultivar `Imperial' and a structural variant carrying an intact 1R chromosome and two telocentric 1R chromosomes (short and long arms)were used to investigate expression patterns of homologous rDNA loci, and the influence of chromosome structural change on their interphase organisation and relative disposition. Sequential silver staining and in situ hybridization with the rDNA probe pTa71, established a correspondence between the expression and organization patterns of rDNA domains in metaphase and interphase cells. In most cells of the cultivar Imperial, nucleolar organizer region (NOR)silver staining on metaphase chromosomes with equivalent numbers of rDNA genes revealed a size heteromorphism between homologous rDNA loci, resulting from their differential expression. NOR heteromorphism in the structural variant line was significantly reduced. The preferential activity of one NOR over its homologue was found to be random within cells and independent of parental origin. Nucleotypic modifications mediated by changes in the 1R chromosome structure include increased proximity between homologous rDNA loci in interphase, and an increase in the frequency of cells with intra-nucleolar ribosomal condensed chromatin. These results seem to indicate a `sequence recognition' process for the regulation of homologous loci.

Mouthpart deformities and nucleolus activity in field-collected Chironomus riparius larvae

Chironomid mouthpart deformities and aberrations of their polytenic chromosomes are sublethal responses to toxic stress. These endpoints have been used in several cases as bioindications for sediment pollution. In the present study we aimed to establish whether there was an association between mouthpart deformities and nucleolus activity in the polytenic chromosomes. Such information could be useful to gain insight into the mechanisms involved in the occurrence of mouthpart deformities and their consequences on the larvae. Third-instar larvae of Chironomus riparius were collected at a site downstream of a sewage treatment plant mostly contaminated by pesticides. Larvae were then raised in the laboratory in aquaria containing sediment and water from the study location. During a 16-day period, larvae ready to molt to the fourth instar were reared individually. Within a few hours of their molt, the larvae were preserved. The presence of mouthpart deformities (mentum, mandibles, and pecten epipharyngis) and the percentage of active nucleoli were assessed. Those larvae presenting mentum deformities had a significantly higher incidence of active nucleoli in their polytenic chromosomes than nondeformed larvae. Because a high number of active nucleoli generally indicates increased rRNA synthesis, deformed larvae seemed to exhibit a higher protein synthesis than normal individuals. The synthesis of additional proteins may increase deformed larva tolerance to toxicants.

Effect of enrofloxacin on AgNOR counts in chick bone marrow nuclei

The mAgNOR and pAgNOR counts reflecting the number of rDNA genes being transcribed, showed a highly significant increase from control values following administration of 5X, 10X, 15X doses of enrofloxacin in chicken. The maximum increase for both, mAgNOR and pAgNOR was shown by birds receiving 15X dose, sacrificed 48 hr after the last drug injection. The increase of pAgNOR at 5X (24 hr) was not significant relative to control values. After 72 hr time interval, AgNOR counts were not feasible due to poor differentiation. Values at 15X (24 hr) showed a decrease in number of AgNOR counts (non-significant) relative to 10X, probably due to depression of transcriptional activity of rDNA genes, which, however, is removed at 48 hr. The general increase in mAgNOR and pAgNOR with dose reflects hypertranscription of rDNA genes so that the birds can cope up with the drug induced toxicity.

[Structural changes of the nucleolar organizing regions in rhabdomyosarcoma RA-23 tumor cells induced by okadaic acid]

It has been recently shown that okadaic acid (OA), an inhibitor of dephosphorilation, is capable of inducing changes in the nucleolar organizer regions (AgNORs) of some mammalian cells. Our work was focused on studying the structural changes in AgNORs of tumour cells of rat rhabdomyosarcoma RA-23 by their exposure to 100 nM OA. A standard silver staining procedure of interphase AgNORs in tumour cells was used. We measured no less than 100 tumour cells in each clone. In the examined tumour cell populations, the index of interphase AgNORs varied from 1.54 to 4.35. A clear structure and form of AgNORs was not observed in 30% okadaic acid-treated tumour cells, as opposed to 10% of the control ones. AgNORs in these cells looked like a mixture of thin threads encompassing some dark dots lying, mostly, separately. Additional procedures of tumour cell staining with Giemsa and fluorescent dye Hoechst 33,258, respectively, revealed that such structures were not chromosomes. Meanwhile, the frequency of cells at the stage of prophase exceeded 3%, as opposed to the control, where the frequency of cells at this stage was less than 0.5%. Thus, we can conclude that we have detected specific changes in AgNORs and chromatin structure of okadaic acid-treated tumour cells.

Chemoprevention of azoxymethane-induced rat aberrant crypt foci by dietary zerumbone isolated from Zingiber zerumbet

The modifying effects of dietary feeding of zerumbone isolated from Zingiber zerumbet on the development of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) were investigated in male F344 rats. Expression of cyclooxygenase (COX)-2 in colonic mucosa exposed to AOM and/or zerumbone was also assayed. In addition, we assessed the effects of zerumbone on cell proliferation activity of crypts by counting silver-stained nucleolar organizer regions protein (AgNORs) in colonic cryptal cell nuclei. To induce ACF rats were given three weekly subcutaneous injections of AOM (15 mg/kg body weight). They were also fed the experimental diet containing 0.01% or 0.05% zerumbone for 5 weeks, starting one week before the first dosing of AOM. AOM exposure produced 84+/-13 ACF/rat at the end of the study (week 5). Dietary administration of zerumbone caused reduction in the frequency of ACF: 72+/-17 (14% reduction) at a dose of 0.01% and 45+/-18 (46% reduction, p<0.001) at a dose of 0.05%. Feeding of zerumbone significantly reduced expression of COX-2 and prostaglandins in colonic mucosa. Zerumbone feeding significantly lowered the number of AgNORs in colonic crypt cell nuclei. These findings might suggest possible chemopreventive ability of zerumbone, through suppression of COX-2 expression, cell proliferating activity of colonic mucosa, and induction of phase II detoxification enzymes in the development of carcinogen-induced ACF.

Chromosomal comparisons among and within populations of Simulium (Chirostilbia) pertinax (Diptera, Simuliidae)

Chromosomal studies were carried on six larval populations of Simulium (Chirostilbia) pertinax from different locations in Brazil. Larvae were collected in the states of Paraná, Rio Grande do Sul, Rio de Janeiro and São Paulo. Polytene chromosome map comparisons within and among populations showed no differences in banding pattern, except for some limited polymorphism (secondary NOR and four band polymorphisms). There were no chromosomal variations associated with the resistance or susceptibility of the larvae to temephos. The chromosomal homosequentiality found among the six populations suggests that S. pertinax may be a monomorphic species.

Abnormal intracellular kinetics of cell-cycle-dependent proteins in lymphocytes from patients infected with human immunodeficiency virus: a novel biologic link between immune activation, accelerated T-cell turnover, and high levels of apoptosis

Human immunodeficiency virus (HIV)-infection is characterized by loss of CD4+ T cells associated with high levels of immune activation, T-cell proliferation, and lymphocyte apoptosis. To investigate the role of intrinsic perturbations of cell-cycle control in the immunopathogenesis of acquired immunodeficiency syndrome (AIDS), we studied the expression of cell-cycle-dependent proteins in lymphocytes from HIV-infected patients. Cyclin B1 expression, Nucleolar Organizer Regions (NORs) number, and NORs area of distribution were all consistently increased in HIV-infected patients, but returned to normal after effective antiretroviral therapy, suggesting that viral replication is directly implicated in the genesis of the observed changes. Analysis of cyclin B1 intracellular turnover showed that the increased cyclin B1 expression is (1) caused by defective degradation in the presence of normal rates of synthesis, and (2) is temporally associated with decreased levels of ubiquitination. After in vitro activation of lymphocytes from healthy individuals, cyclin B1 and cdc25 expression and ubiquitination, p34 cdc2 activity, NORs morphology, and C23/nucleolin localization showed a 72- to 96-hour cyclic pattern that led to a biologic state similar to baseline. On the contrary, complex but consistent changes of the same indices followed activation of T lymphocytes from HIV-infected patients, resulting in a 5-fold increase in apoptosis. Overall, our data indicate that a profound dysregulation of cell-cycle control is present in lymphocytes from HIV-infected patients. This finding may provide a novel biologic link between immune activation, accelerated lymphocyte turnover, and increased apoptosis during HIV infection.

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.

Evaluation of nucleolar organizer regions in tumours of the jaw bones

Nucleolar organizer regions [NORS] are loops of DNA that transcribe to ribosomal RNA. They can be visualized as intranuclear black dots by histochemical staining with a colloid silver solution. Silver stained nucleolar proteins (AgNORs) were counted in a variety of jaw bone tumours. In osteosarcomas, the number of AgNORs was also quantified before and after chemotherapy. Malignant bone tumour cells possessed more than five small AgNORs (5.54 +/- 0.44). Nuclei of benign jaw bone tumour cells had less than three (2. 97 +/-0.61). A significant difference in the number of AgNORs between osteosarcoma before chemotherapy (5.76 +/- 0.50) and after chemotherapy (3.89 +/- 1.65) was observed. (P < 0.05). The number ofAgNORs in recurrent osteosarcoma, recurrent ameloblastic carcinoma and recurrent chondrosarcoma was much higher than in their respective primary lesion but without statistical significant difference. The results of the present study indicate that the AGNOR count might help in determining malignancy, evaluating the effect of chemotherapy, and deciding the prognosis.

Altered remodeling of nucleolar machineries in cultured hepatocytes treated with thioacetamide

Thioacetamide (TA) is converted into a hyperacetylating agent which causes hepatic necrosis, regeneration, cirrhosis and cancerous transformation. One of the most characteristic toxicities of TA in rat is observed with a 50 mg/kg per day which induces nucleolar enlargement different from that in regenerating liver. From TA-treated liver, the nucleoli were isolated and characterized for an altered nucleolar signal transduction system. Immunochemistry revealed that the poisoned nucleoli had increased levels of both nucleolus specific proteins (nucleophosmin and nucleolin) and various signal molecules (CK2, Erk1/2, p38, protein kinases A and C, and cyclin A). Using flow cytometry, the nucleoli were found to be in G2-arrested nuclei. Manifestation of the nucleolar enlargement could be readily observed using an ex vivo hepatocyte culture. There were two types of nucleolar enlargement. One was observed in normal hepatocytes with light density of enlarged nucleoli. The other was in TA-treated hepatocytes with dense and compact density of enlarged nucleoli, which contained a 3 to 5-fold higher nudeophosmin content than the control. In vitro induction of nucleolar enlargement with TA was possible. As soon as the hepatocytes anchored on a collagen coat, exogeneous TA (higher than 1 microg/mL) could induce dense and compact nucleoli. However, when an exogeneous drug was added after monolayer formation (1 day), no drug-induced nucleolar enlargement was observed.

The effect of desalivation on 4-nitroquinoline-1-oxide-induced tongue carcinogenesis: a morphometric study of nucleolar organizer regions

Saliva is an important factor in the oral cavity and could be significant in protecting against carcinogens. In experimental models of carcinogenesis, saliva was shown to have a temporary protective effect against the carcinogens DMBA and 4-nitroquinoline-oxide (4NQO). Silver-stained nucleolar organizer regions (AgNORs) are considered markers for both proliferative capacity and prognosis. The purpose of the present study was to investigate the effect of desalivation on AgNOR parameters in lesions induced by the carcinogen 4NQO in a rat model, in order to trace early nuclear changes. The study group consisted of 120 male Wistar-derived rats. The experimental group (n=56) underwent surgical desalivation; the control group (n=56) underwent a sham operation, and both groups were administered a solution of 0.001% 4NQO in the drinking water. A normal group (n=8) did not receive surgery and drank tap water. Rats were sacrificed at 7, 14, 22, and 28 weeks. Formalin fixed, paraffin embedded sections of the tongue were silver-stained and AgNOR parameters were analyzed using computerized image analysis. In both desalivated and control groups, the nuclear area was significantly higher than the normal. This difference was already evident at 7 weeks. The mean AgNOR area was significantly higher in the desalivated group at week 7 and continued to increase over time. The mean AgNOR number was also significantly higher in the desalivated group at week 7. Differences between the desalivated and control groups diminished with time. These changes in proliferative activity, as expressed by AgNOR parameters, presented earlier changes in comparison to those observed in microscopic examination of the same slides. Results suggest that saliva in the oral cavity can delay malignanttransformation, but continued exposure to the carcinogen overrides this effect. AgNOR stain seems to be sensitive and allows for early identification of intranuclear changes.

[Effect of fusococcin on the genome of common wheat]

The effect of fusicoccin on the common wheat genome (cv. Mironovskaya 808) during early phases of seed germination was studied. It was shown that fusicoccin: (1) increased the number of cells with one or two nucleoli and decreased the proportion of cells containing three and four nucleoli; (2) enhanced the total volume of nucleoli per nucleus at a concentration of 0.68 mg/l; (3) did not activate additional rRNA genes on chromosomes 1B and 6B; (4) did not activate the latent nucleolus organizer regions on chromosomes of genome B; (5) induced associations of nucleolus organizer regions on B-genome chromosomes; (6) significantly enhanced mitotic activity in apical meristem of seedling root tips and promoted the first peak of mitoses; the effect disappeared after 44 h of seed imbibition; (7) in contrast to gibberellin, did not synchronize cell division; (8) did not cause chromosome and chromatid aberrations and increase the frequency of sister chromatid exchanges at physiologically active concentrations. Presumable mechanisms of fusicoccin-induced activation of rRNA genes are discussed in relation to the identification of the fusicoccin receptor belonging to the GF14 proteins with an intracellular binding site, to the detection of endogenous fusicoccin in plants in vivo, and to fusicoccin-induced activation of gene transcription.

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.

[Effects on organ-development of mouse embryo by inhibiting NOR activity]

It is reported here that the NOR activity of mouse embryonic cells treated with BrdU in Vitro. The NOR activity could be recovered after incubating the cells in the BrdU-free medium. The inhibition of NOR activity in the early and mid-term gestation led to abnormal development as follows: the increase of fetus abortion in vivo and death rate of newborn offsprings, causing a congenital blindness in the newborn offsprings. The main reason for the blindness is a contamination of a plenty of the untransparent granules with a size of 0.3 micron in diameter from the epithelial cells. The relationship between the transcription of 18S and 28S rRNA genes and the embryonic organ development is also discussed in this paper.

Chemopreventive effects of coumaperine from pepper on the initiation stage of chemical hepatocarcinogenesis in the rat

This study was designed to investigate the chemopreventive action of three natural products, coumaperine, aurapten and an extract from rosemary, against the initiation stage of rat hepato-carcinogenesis. Coumaperine has been isolated from white pepper as a naturally occurring antioxidative agent, but its potential modifying effects on carcinogenesis remain unclear. In experiment 1, a modification of the model developed by Tsuda et al. was applied, with assessment of numbers and areas of induced glutathione S-transferase placental form (GST-P)-positive hepatocellular foci in male F344 rats. Coumaperine, aurapten and the extract from rosemary were administered i.g. at 100 mg / kg / day once daily for 5 days with initiation by diethylnitrosamine (DEN) on day 4 (20 mg / kg, i.p.). Numbers and areas of GST-P-positive foci in each group given test chemicals tended to be decreased as compared to the vehicle control group values, significance being achieved for number with coumaperine. Experiment 2 was planned to investigate the mechanism of the inhibitory effects of coumaperine. Livers at 8 h after initiation by DEN were examined with coumaperine administered at 100 mg / kg / day once daily for 3 days. Proliferating cell nuclear antigen (PCNA)-positive cells tended to be decreased as compared to the vehicle control, but no effects on apoptosis or cytochrome P-450 (CYP) 2E1 expression were apparent. Our results suggest that coumaperine provides protection against initiation of hepatocarcinogenesis, and that this is related to inhibition of cell proliferation.

HaeIII induces position-dependent chromosomal breakage in barley (Hordeum vulgare L.)

The pattern of localized chromosomal breakage induced by the restriction endonuclease HaeIII in reconstructed barley karyotypes T-1586 and T-21 was investigated. It was found that nucleolus organizing regions (NORs) of chromosomes 6 and 7 (segments 46 and 38, respectively), containing actively transcribed ribosomal (r)DNA, as well as segments 39 and 47, both containing condensed rDNA repeats, are the most pronounced aberration hot-spots in T-1586. The number of aberrations observed in these segments was three to five times higher than theoretically expected. The intrachromosomal distribution of chromatid aberrations in karyotype T-21, where the NOR-bearing segments in chromosomes 6 and 7 change their position, revealed a substantial difference in the aberration hot-spot behaviour. A position-specific increase in aberration clustering was observed, most pronounced in segments 38 and 47. On the other hand, segment 46 retained its initial sensitivity, while segment 39 in the new position lost its previous status as a mutation hot-spot. The data are indicative of the expressivity of aberration hot-spots generated after treatment with this restriction endonuclease being influenced by their distinct chromosomal location.

The Saccharomyces cerevisiae Cdc14 phosphatase is implicated in the structural organization of the nucleolus

Cdc14, a dual-specificity protein phosphatase, has been previously implicated in triggering exit from mitosis in the yeast Saccharomyces cerevisiae. Using immunofluorescence microscopy and immunogold labeling, we demonstrate that a functional HA-tagged version of the phosphatase Cdc14 localizes to the nucleolus. Moreover, Cdc14-HA co-localized with the nucleolar NOP2 and GAR1 proteins. By immunofluorescence, Cdc14-HA was found in the nucleolus during most of the mitotic cell cycle, except during anaphase-telophase when it redistributed along the mitotic spindle. While this work was in progress, the same pattern of Cdc14 localization was described by others (Visintin et al, Nature 398 (1999) 818). Constitutive overexpression of CDC14 was toxic and led to cell cycle arrest of cells, mainly in G1. This correlated with the appearance of abnormal nuclear structures. A genetic search for suppressors of the lethality associated with CDC14 overexpression identified YJL076W. Because overproduction of Yj1076w buffered the toxic effect of Cdc14 overproduction, this suggested that it might be a substrate of Cdc14. This has indeed been found to be the case by others who recently described Yj1076w/Netl as a nucleolar protein that physically associates with Cdc14 (Shou et al, Cell 97 (1999) 233). The present data confirm several recently uncovered aspects of the regulation of Cdc14 localization and activity and suggest that the level of expression of CDC14 influences the structural organization of the nucleolus.

Changes in AgNOR configurations during the evolution and treatment of chronic lymphocytic leukemia

The evolution of the pattern of nucleolar organiser regions (AgNORs) in circulating lymphocytes during the stable phase and after chemotherapy in CLL was analysed. Peripheral blood smears were stained by the AgNOR technique at diagnosis, during observation follow-up in stable phase, or at the beginning and at the end of chemotherapy in patients with progressive disease. The changes in the AgNOR pattern were compared with those of TTM used as a tumour burden parameter. Among 52 cases that entered the study, 29 were in stable phase and 23 had progressive disease and received chemotherapy. During stable phase, the AgNORs as well as TTM remained constant. In treated patients, the relative reduction of tumour mass was correlated with a decrease in the percentage of lymphocytes containing one AgNOR cluster. The percentage of cells with one compact nucleolus before chemotherapy was inversely correlated with the relative amount of tumor reduction after treatment. We conclude that the AgNOR pattern in CLL describes the cell kinetic changes during the evolution of the disease and is a prognostic factor for tumor reduction after treatment.

Histomorphometry and quantification of nucleolar organizer regions in bovine thyroid containing methylthiouracil residues

In order to study the morphology and morphometry and to characterize and quantify the nucleolar organizer regions (NORs) of bovine thyroids containing methylthiouracil (MTU) residues, five animals were orally treated with a suspension of MTU (5 g/animal/day) for 20 days (group A). This treatment protocol was interrupted 5 days before the the animals were slaughtered. Six animals receiving placebos composed group B. A third group (group C) was composed of normal thyroids obtained from a slaughterhouse. All glands were previously assessed for detection of antithyroid residues by chromatography, and only those glands from MTU-treated animals were positive. Follicles of glands from group A showed wide variation in size and shape. There was a predominance of small follicles covered by multiple layers of columnar cells, sometimes forming papillary projections into the lumen, characterizing severe interfollicular and intrafollicular adenomatosis. Many follicles had vacuolated cells with nuclei showing karyolysis or pyknosis and reduced amounts of a low-density and very excavated colloid. They also showed higher follicular epithelia and larger proportions of their structural components when compared with glands of groups B and C. In the thyroids from group A, the argyrophilic nucleolar organizer region-associated proteins (AgNORs) were greater in number, with small ones scattered all over the nucleus. Although the size of AgNORs in thyroids from groups B and C was variable, these AgNORs were fewer and larger than were those in glands from group A. In conclusion, the MTU induces proliferation and regressive changes in follicular cells, and the AgNOR technique is efficient to distinguish different degrees of thyroid hyperplasia.