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Biomedical subjects

C Pellicciari

Publications and source records attributed to C Pellicciari.

At least 73 records · Page 4Linked to original sources
PubMed1988

Genome size and constitutive heterochromatin in Hylobates muelleri and Symphalangus syndactylus and in their viable hybrid.

Genome size was measured as the amount of Feulgen-stained DNA in six species of the family Hylobatidae and in a hybrid of the gibbon (Hylobates muelleri) and siamang (Symphalangus syndactylus). The family, on the whole, exhibits a wider range of genome sizes than pongids; in particular, the siamang has about 15% more DNA than the 44-chromosome Hylobates species of the "lar" group. Quantitative analysis of C-heterochromatin in hybrid metaphases showed that the difference in genome size of the parental species correlates with the amount of C-band-positive material. Hylobatids are the only group of primates in which karyotype diversification has taken place with a massive quantitative change in constitutive heterochromatin.

Animals↗
PubMed1987

Influence of cis-dichlorodiamineplatinum on glioma cell morphology and cell cycle kinetics in tissue culture.

C6 glioma cells (CCL 107) were cultured for three days and then treated with cis-dichlorodiamineplatinum (cis-DDP) at doses of 0.2-10 micrograms/ml medium. Changes in DNA synthesis and DNA content, as well as morphology of cells and chromatin distribution, were examined from the first post-treatment day onwards. The number of cells labelled with [3H]thymidine, detected autoradiographically, decreased after treatment with 0.2-10 micrograms/ml by approximately one half on post-treatment day 1 and diminished further by the third day after treatment. The labelled cells were entirely absent only after treatment with 10 micrograms/ml, 7 days post-treatment. Mitoses decreased from 1.4-0.6% by post-treatment day 1 and completely disappeared by day 3 (1 microgram/ml). Feulgen cytophotometry and propidium iodide cytofluorimetry revealed accumulation of cells in the S-phase, especially the latter part (0.5 and 1.0 micrograms/ml, post-treatment day 1) and subsequently also in G2 phase (post-treatment day 3). Incomplete cyto- and karyokinesis in some cycling cells was indicated by an increased number of binucleate cells and nuclei of higher ploidy classes. Labelled cells with intermediate DNA values were, on average, labelled less intensively, as was revealed by simultaneous measurements of DNA content and [3H]thymidine incorporation. Some cells displayed reduction in grain density over heterochromatin clumps. This would be in agreement with the late S-phase block of DNA replication. After post-treatment day 3 the density of cells in cultures was substantially lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Kinetics of DNase I digestion of interphase chromatin in differentiated cell nuclei of the mouse: a flow cytometric study.

The process of DNA digestion with DNase I was monitored in interphase chromatin of differentiated cells by flow cytometry after DNA staining with either the intercalating dye propidium iodide (PI) or the AT specific dye Hoechst 33258 (HO). Nuclei from the liver, kidney and spleen of the mouse were studied after different digestion times (0 to 120 min). During the first 30 min of treatment, a tissue specific digestion pattern was found after PI staining; from 60 min onward, the digestion curves ran parallel, with minor quantitative differences among the cell types. After HO staining, the digestion kinetics appeared to be similar for all the cell types; this is likely due to the peculiar base composition of the mouse genome, where inactive c-heterochromatin is exceptionally AT-rich. No quantitative correlation was found between interphase "heterochromatin" and chromatin DNA which is resistant to DNase I cleavage, while the amount of DNase-I-sensitive DNA does not correspond to the interphase "euchromatic" component. It was confirmed that the flow cytometric approach is a tool for quantifying relative changes in the functional state of chromatin in differentiated cell systems.

Animals↗
PubMed1986

Sperm-chromatin maturation in the mouse. A cytochemical approach.

Cytochemical techniques were used to study chromatin during spermiogenesis and sperm maturation in the mouse, starting from the stages at which the substitution of somatic histones by testis-specific proteins occurs. It was possible to distinguish and analyze the different temporal incidence of two processes involved in sperm maturation, i.e. chromatin condensation (a tridimensional highly compacted arrangement) and chromatin stabilization (a tough structure, which protects the genome DNA). The first process, involving a reduction in the nuclear size and a decrease in the amount of sperm DNA accessible to specific cytochemical reactions and stainings, was found to reach its maximum in caput-epididymidis spermatozoa, in which electron microscopy revealed that the sheared chromatin was mainly organized into 120-A-thick knobby fibers. No further changes were found in sperm up to their appearance in the fallopian tubes. On the contrary, chromatin stabilization, the onset of which occurs in the testis (at the late spermatid stage) via the formation of -S-S- cross-links, is completed in the vas deferens, where chromatin has a superstructure consisting of thicker fibers, with diameters of 210 and 350 A. The reductive cleavage of disulfides in vas-deferens spermatozoa does not completely destroy the superstructure of sperm chromatin, which could indicate 'coiling' of the basic knobby fiber. In fact, when the ion concentration was increased, the chromatin of vas-deferens spermatozoa appeared to be organized into fibers with diameters similar to those of the caput epididymidis. This unique organization of mature sperm chromatin should have an essential role in the fast swelling of spermatozoa during fertilization.

Animals↗
PubMed1985

Computer analysis of sub-parameters of depurination and depolymerization rate constants in Feulgen DNA hydrolysis.

Feulgen DNA hydrolysis curves derived from cytofluorometry at various temperatures and HCl concentrations were computer analyzed with least squares fit to Bateman function. By comparing the depurination (k1) and depolymerization (k2) rate constants at different hydrolysis conditions, it was found that the two parameters of temperature and HCl concentration can be expressed as k = AN2 X exp (-B/T), where A and B are constants, N is the HCl concentrations, and T is the absolute temperature. From the analysis of Feulgen hydrolysis curves with 2N HCl at various temperatures, it was calculated that A = 5.3590 X 10(14) and B = 12133.543, for k1, and A = 6.2401 X 10(14) and B = 12181.660, for k2 for mouse 4C hepatocytes fixed with absolute methanol. Computer generated theoretical hydrolysis curves using the above k1 and k2 values were compared with experimental curves at various temperatures and HCl-concentrations. The two types of hydrolysis curves coincided with each other when 1-3 N HCl was used at temperatures between 30-40 degrees C. The peak times of hydrolysis curves at different conditions determined by experimental analysis and theoretical estimations also coincided reasonably well with each other. The physico-chemical phenomena underlying the equation designating k1 and k2 values are discussed.

Animals↗
PubMed1984

The presence of G1 and G2 populations in normal epithelium of rat urinary bladder.

The cell population kinetics of transitional epithelium of the rat urinary bladder was analysed by (3H) thymidine autoradiography and pararosanilin Feulgen DNA cytofluorometry. By flash and 72 h continuous DNA labelling, the generative cells of the transitional epithelium were found to be well localized in the basal layer, and it was postulated that che cells produced by cell proliferation in the basal layer would migrate towards the surface, maintaining direct attachment to the basement membrane by anchorage of a cellular process. Analyses of normal and wounded transitional epithelium revealed that 58.8% of all basal cells are G0 cells in G1 phase (G1-population), and 59.0% of the remaining basal cells reside in prolonged (75.1-108.0 h) G2 phase, preserving the ability to divide (G2-population). The cell cycle time of the generative basal cells including the long G2 phase was calculated as 129.1-162 h. All the cells existing in upper layers were found to be also G0 cells in G1 phase, with the DNA amounts of 2C class. No polyploid cells could be detected except for 2C-2C binucleated cells in the superficial layer. The existence of a G2-population may serve for the urgent need of cell incrementation to repair cell loss as the cells in G2 phase can divide without the time-delay needed for DNA synthesis. The rat transitional epithelium, which is composed exclusively of proliferating and potentially proliferative cells, will have much greater capability to repair damage than stratified squamous epithelia.

Animals↗
PubMed1983

Cytofluorometric study of nuclear sulphydryl and disulphide groups during sperm maturation in the mouse.

The amount of nuclear sulphydryl and disulphide groups was determined by cytofluorometry on single mouse spermatozoa from the caput, corpus and cauda epididymidis, and the vas deferens. N-(7-Dimethylamino-4-methylcoumarinyl) maleimide was used as a specific and quantitative fluorescent reagent for thiols. The sperm nuclear content of free sulphydryl groups decreased sharply from the caput epididymidis to the vas deferens. The amounts of cysteine residues present as the thiol form in the spermatozoa from the caput, corpus and cauda epididymidis and vas deferens were 50, 15, 5 and 3% respectively.

Animals↗
PubMed1983

Mitomycin C-induced acceleration of liver cell polyploidization in adult rat after partial hepatectomy.

Mitomycin C, a DNA cross-linking agent, was administered for a week intraperitoneally to a normal 9-week-old rat in which hepatocyte proliferative activity had almost ceased. In the rat treated with mitomycin C, the number of polyploid cells with the DNA amounts more than 4C was not increased in comparison with that in the control rat without any treatment. However, the partial hepatectomy in the rat pretreated with mitomycin C provoked prominent hepatocyte polyploidization much greater in degree than that found in the hepatectomized rat without mitomycin C treatment. These results seem to indicate that the existence of cross-linking DNA damages is a latent factor necessary for the induction of abortive mitosis of a cell after completion of DNA synthesis, which results in the production of a mononuclear polyploid cell in one-step higher DNA class. Cross-linking DNA damages and DNA synthesis are the essential factors for the manifestation of polyploidization.

Animals↗
PubMed1983

A method of DNA histogram analysis by computer and its evaluation by simultaneous combination with 3H-thymidine autoradiography.

A method for determining the fractions of cells in the G1, S, and G2 + M phases of the cell life cycle, by quantifying DNA histograms derived from static fluorescence cytophotometry, was evaluated by simultaneous combination with 3H-thymidine autoradiography. DNA histograms were obtained by cytofluorometry on the Feulgen-stained autoradiographs of HeLa cells, and mouse and rat hepatocytes, after DNA labelling with 3H-thymidine. The synthetic histogram determined by "sum of discrete normal curves" technique was fitted to the experimental data according to a weighted least-squares method by a desk-top computer (HP 85F). The mean relative percent deviations of estimated cell cycle phase fractions from the actual phase fractions determined directly on an autoradiograph was 6.6 +/- 3.3%.

Aging↗
PubMed1982

Cytochemical assessment of chromatin characteristics during sperm cytodifferentiation in mouse.

Cytochemical quantitative reactions either for DNA or proteins were performed on spermatozoa in the last stages of the sperm cytodifferentiative process. The analysis of the discrepancy between the expected (1C amount) and the evaluated reaction intensities sheds light on the chromatin condensation phenomenon. The high inactivation and protection of the paternal genome in a particularly packed chromatin has generally been regarded as the cause of non-stoichiometric responses by DNA specific reactions. We suggest that this interpretation fits well for specific DNA reactions based on intercalation between base pairs or DNA phosphate groups binding, but for the Feulgen reaction the cause is more complex and pertains to the particular susceptibility of the sperm chromatin to depolymerization by hydrolysis in the Feulgen reaction.

Animals↗
PubMed1981

The effect of different fixatives on chromatin: cytochemical and ultrastructural approaches.

This study explores the effects of two types of fixative on chromatin. The first type (acrolein, glutaraldehyde) engenders a high degree of ultrastructural preservation. The other type are fixatives that are widely used in cytochemistry and cytogenetics (acetic acid, 3:1 by vol. methanol-acetic acid, methanol alone, formaldehyde). Lymphocytes of adult rats so-fixed in vitro were prepared for electron microscopy or microdensitometric evaluations of smears. Assessments were made of variations in their total protein, nuclear basic protein and DNA contents. DNA was determined both as Feulgen-positive material and by its binding of intercalating dyes (Methyl Green, specific for double-stranded polynucleotides). Our results showed that some fixatives break up the chromatin organization by acting on particular components of chromatin fibres. They can thus be considered to be destructive agents in situ. In addition, a revaluation of some aldehyde fixatives is proposed for both ultrastructural and cytochemical research.

Acrolein↗
PubMed1981

Analysis of some cytotopochemical parameters for a definition of the chromatin status.

A study of the curves of Feulgen hydrolysis kinetics has been performed on different cell types of the same animal species and on the same cell type from different species at different taxonomical level. The curves were analyzed by a computer programme of least square fit to the Bateman's function, which gives a description of DNA hydrolysis kinetics by three parameters only: 1) amount potentially stainable groups; 2) depurination rate constant; 3) depolymerization rate constant. The chromatin homogeneity within the nucleus seems to affect these parameters, together with the degree of chromatin compaction. Furthermore the thermal denaturation (100 degrees C), also after fractionate histone extraction, shows a resistant DNA fraction, which does not appear to be affected by the degree of chromatin compaction only.

Animals↗
PubMed1981

Some parameters for a cell cycle cytotopochemical study.

With the Feulgen-Naphthol Yellow double reaction we dosed, simultaneously on a cell, [1] the DNA nuclear content (as Feulgen positive material), [2] the protein cell content and [3] the Feulgen chromatin area; the degree of condensation is expressed by the ratio [1]/[3]. The evolution of the lymphocytes culture at different times of PHA stimulation was in this way studied with the aim of defining the existence of cell subpopulations pertaining at different phases or subphases of the cycle.

Blood Proteins↗
PubMed1980

The Feulgen hydrolysis kinetics in the midgut cell classes of the stick insect Bacillus rossius: a computer analysis.

In the midgut epithelium of the walking stick insect Bacillus rossius, nuclei belong to two main cytological categories: nuclei with ordinary chromatin (ON) showing a polyploid series of Feulgen-DNA contents (2, 4, 8, 16C) and nuclei with DNA-RNA bodies (NWB) varying from 9 to 34C. Cells with ON are either small basal or large secretory elements, while those with NWB always belong to the second type. The Feulgen kinetics profiles obtained after formalin fixation, as well as their least squares fit by computer analysis, have shown that with increasing ploidy both the aldehydic group availability and the resistance to depolymerization increase in the genomes of ON; on the contrary, NWB have a depurination rate and resistance to depolymerization significantly lower than the ON. The kind and magnitude of the changes observed, while suggesting a gradually different DNA-protein relationship with increasing ploidy and concurrent maturation of ON, also indicate a deeper chromatin reorganization for NWB.

Animals↗