Diurnal variations in endogenous RNA polymerase activity and amounts of nuclear non-histone protein, DNA and cytoplasmic protein in rat liver

Detection of metabolic changes in hepatocytes by quantitative cytochemistry

Studies by means of quantitative histochemistry and cytochemistry have greatly contributed to the knowledge of metabolic changes in liver parenchymal cells. In the present paper recent work along this line is reviewed with emphasis on three topics, polyploidy as a source of metabolic heterogeneity, proteolysis in the regulation of hepatocyte cell mass and ischemic injury of hepatocytes. In all three fields, accuracy and precision of information obtained by quantitative histochemical means has been greatly enhanced by a thorough knowledge of the mechanisms of histochemical reactions obtained by fundamental work on matrix chemistry, and well-considered application of optical measuring tools and conditions of measurement. These are the principles put forward by van Duijn since the pioneer period of histochemistry and to whom this review is dedicated.

Daily changes of protein synthesis and secretion rates in rat liver slices

The rates of protein synthesis and secretion in rat liver slices showed temporal variability, as assessed by the use of [14C]leucine. The protein synthesis showed daily changes with two maxima at 13:00 and 01:00 hr and minimum at 17:00 hr. The secretion rate also varies within 24 hr showing biphasic pattern. The pattern of daily secretion rate for hydrophobic proteins differed from the pattern observed for acid proteins and glycoproteins.

Temporal changes of acid phosphatase, arylsulphatase, beta-galactosidase and beta-N-acetyl-D-glucosaminidase activities in subcellular fractions of rat liver

In this paper circadian changes in the liver enzyme activities of rat housed under highly standardized conditions with 12: 12 hour light-dark cycle are shown. Activities of acid phosphatase, arylsulphatase, beta-galactosidase and beta-N-acetyl-D-glucosaminidase in microsomal and lysosomal fractions and crude homogenate were estimated every 4 hr during one 24-hr period. The enzyme activities were related to 1 mg of protein, 1 mg of DNA and 1 g fresh tissue. Daily changes of enzyme activities were found. In case of activity calculated per 1 mg DNA two maxima at 0500 and at 2100 hr were observed, while activity calculated per 1 mg protein showed one maximum at 0500 hr. Activity calculated per 1 g fresh tissue showed the maximum at 0500 hr for each enzyme only in microsomal fraction. As far as acrophase table is concerned for all enzymes and fractions the acrophase occurred during the night. The obtained results are discussed in relation to lysosomal enzymes synthesis process as well as different reference values.

Ploidy class-dependent variations during 24 h of glucose-6-phosphate and succinate dehydrogenase activity and single-stranded RNA content in isolated rat hepatocytes

The time-dependent variations over 24 h of glucose-6-phosphate dehydrogenase (G6PDH) activity, succinate dehydrogenase (SDH) activity and single-stranded RNA (ssRNA) content have been investigated by cytophotometric analysis of cytochemically stained isolated hepatocytes of different ploidy classes from adult male rats. A marked variation of 48% over the day in G6PDH activity of the mononuclear diploid cells was revealed, but no significant variation in the binuclear tetraploid cells. The cells of the inbetween ploidy classes showed an amplitude of variation of 38% (binuclear diploid cells) and 24% (mononuclear tetraploid cells), respectively. All cells showed a maximum activity of the enzyme at the middle of the day and a minimum during the night. The relative enzyme activity per mononuclear diploid cell was significantly higher than the relative activity in the other cells, especially at its maximum. The variation of the SDH activity in hepatocytes isolated from the same rats was similar in all cells, irrespective of their ploidy class. The activity was highest at the end of the activity phase of the animals. The SDH activity per cell was directly proportional to the quantity of genome copies. The ssRNA content of the hepatocytes showed a time-dependent variation with a maximum during the resting phase of the animals and a minimum during their activity phase. The variation was larger in the mononuclear diploid cells than in the cells of other ploidy classes and the ssRNA content was also significantly higher in these cells than in the hepatocytes of other ploidy classes when calculated on the basis of genome copies. It is concluded that the large amplitude of variation over the day and the high relative amount of G6PDH activity and ssRNA content in mononuclear diploid cells is related to the function of these cells as stem cells of the liver parenchyma.

Quantification of nuclear non-histone proteins by Feulgen--Naphthol Yellow S cytophotometry

Owing to the accumulation of nuclear non-histone protein (NHP) (a) in cells entering the cell cycle from the quiescent state and (b) in continuously cycling cells during G1 phase, a simultaneous determination of DNA and nuclear NHP is of high potential utility in cell kinetic studies. This paper provides guidelines for a Feulgen--Naphthol Yellow S staining technique for this purpose. It discusses details of the preparation and quantification procedures, and reviews the evidence for a quantitative relationship between nuclear Naphthol Yellow S binding and nuclear NHP.

Cytophotometry of liver cells from ethanol-fed rats: ethanol causes increased polyploidization and protein accumulation

Cellular protein and DNA content were determined by Feulgen--Naphthol Yellow S cytophotometry on isolated liver cells from rats fed ethanol for 2--6 months. It was found that parenchymal liver cells after ethanol feeding contained 13% more protein than cells of the same ploidy class from controls; that the average parenchymal cell in ethanol-fed rats contained 16% more protein than in controls due to the increased occurrence of polyploid cells; that the protein accumulation develops over 2 months, does not progress thereafter and disappears after a few days of reduced ethanol intake; that the tendency to form polyploid cells is accentuated during liver regeneration. It is suggested that the effect of alcohol on microtubular function, which is regarded as the cause of the protein accumulation, may also bring about increased polyploidization.

Protein staining methods in quantitative cytochemistry

The chemical action and practical application of the Naphthol Yellow S, Alkaline Fast Green, Coomassie Brilliant Blue, Dinitrofluorobenzene and some lesser known protein staining methods have been surveyed with respect to their potentialities for quantitative cytochemical analyses. None of the dyes can be said to bind to any specific protein or group of proteins, but each may be used to analyse the presence of one or more particular amino acid residues. For the cytophotometric measurement of the 'total protein content' of individual cells and cell organelles the covalent binding Dinitrofluorobenzene and the electrostatic binding Naphthol Yellow S can properly be used. Fast Green FCF, applied at alkaline pH, binds electrostatically to the basic amino acid side chains of strongly basic proteins only but not in a quantitative (stoichiometrical) way. Coomassie Brilliant Blue, recently introduced to protein cytochemistry, may be useful for quantitative purposes. The combined Feulgen-Pararosaniline(SO2)/Naphthol Yellow S and Dinitrofluorobenzene/Feulgen-Pararosaniline(SO2) methods enable the simultaneous cytophotometric analysis at two different wavelengths for protein and DNA within the same microscopical preparation.

Adaptation of the Naphthol Yellow S staining for objects with high protein content

In measuring isolated rat liver cells stained with Naphthol Yellow S (NYS) at optimal conditions of pH (2.8), the absorbances measured at the absorption peak of 430 nm appeared to be far too high locally to enable accurate cytophotometric measurements. In order to bring down these absorbances, different techniques for flattening the cells, off-peak measurement and NYS staining at non-optimal pH levels have been applied respectively. Using albumin incorporated in polyacrylamide model films, the reliability of off-peak measurements and the quantitative aspects of the modified protein staining procedures have been investigated. It was found that the NYS procedure can be used as a quantitative protein staining not only at pH 2.8, but also at pH 2.0, 3.5 and 4.0 respectively. The problem with regard to the cytophotometric measuring of isolated liver cells could only be solved, however, by combining a specially developed flattening procedure (by centrifuging small drops of suspension) with staining at non-optimal pH levels. In contrast to the model film results, off-peak measurements applied in situ appeared to give rather unreliable results. In cases of a combined Feulgen-NYS staining, the Fuelgen-DNA values were not significantly influenced by any of the modifications of the original NYS staining procedure.

Nuclear non-histone protein content of G0/G1 cells as related to growth fraction in mouse mammary tumors

In eight mouse mammary tumors with varying growth fractions DNA and non-histone nuclear protein (NHNP) were determined by absorption cytophotometry of Feulgen-Naphthol Yellow S stained, isolated cells. It was found that: 1. The mean NHNP content of cells with postmitotic DNA content (G0 + G1) increased with increasing growth fraction. 2. The mean NHNP content of S and G2 cells in the eight tumors did not vary significantly with growth fraction. 3. The frequency distributions of NHNP in G0/G1 cells were unimodal and right-skewed. The results are interpreted as follows: A) G0 cells differ from G1 cells by their lower content of NHNP. B). If it is assumed that the G0 and G1 compartments are arranged in series, the cells in the transition from G0 to late G1 may account for the unimodality and skewedness of the NHNP frequency distributions of postmitotic cells.

Feulgen-Naphthol Yellow S cytophotometry of liver cells. The effect of formaldehyde induced shrinkage on nuclear Naphthol Yellow S binding

1. In isolated liver cells, fixed in 4 per cent formaldehyde (NFS) for Feulgen-Naphthol Yellow S (F-NYS) staining of DNA and protein, nuclear shrinkage increases the nuclear concentration of solids to 46 per cent (w/v) before the start of the NYS staining. 2. When a fixative mixture of methanol:acetic acid:formalin (85:5:10 by volume; MAF) is used, the concentration of nuclear solids during NYS staining remain at a physiological level of 19 per cent. 3. By exposing liver cells to NFS for 10 to 120 seconds before fixation in MAF, increasing nuclear shrinkage can be induced with increasing pretreatment in NFS. Nuclear NYS binding decreases in parallel with the decreasing nuclear volume in cells thus treated. As the shrinkage induced reduction in NYS binding may vary with the net charge of nuclear non-histone proteins, MAF fixation must be preferred for quantitative determinations of nuclear non-histone protein in F-NYS stained, isolated cells. 4. Fixation in MAF offers the same advantages as NFS fixation as regards the small loss of proteins during the Feulgen staining procedure and the excellent reproducibility of the F-NYS staining. Storage of MAF fixed cells in the fixative for a few days does not alter their F-NYS staining properties. 5. In MAF fixed, F-NYS stained cells there is no NYS binding to histone basic amino acid residues.