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F Szeszák

Publications and source records attributed to F Szeszák.

At least 19 recordsLinked to original sources
PubMed2001

Expression and rapid one-step purification of biologically active His-tagged factor C by Ni(2+) affinity column chromatography.

Factor C is an unusual extracellular protein capable of inducing cytodifferentiation in certain Streptomyces strains. The protein is produced by Streptomyces griseus 45H at such a low amount that the study of its mode of action was hindered by the shortage of purified protein. We report here the expression of C-terminally hexa-His-tagged factor C in Streptomyces lividans and Escherichia coli. Expression in S. lividans is low while in E. coli it is relatively high, yielding about 5--10 mg of biologically fully active protein per liter culture.

Amino Acid Sequence↗
PubMed1999

Identification of factor C protein from Streptomyces griseus by microelectrospray mass spectrometry.

Factor C, an extracellular signal protein of cellular differentiation, was studied and significant homology was found to several zinc finger-type regulatory proteins. The complete amino acid sequence, deduced from the gene, that encodes the protein, did not support the hypothesis that this protein might be a zinc finger-type regulatory protein. However, a theoretical single nucleotide insertion in the gene can result in another similarly sized protein containing about 20 His residues, which would be responsible for the high zinc affinity of factor C. The protein sample was reduced, alkylated and then in-gel digested with trypsin. The peptide fragments were then separated by capillary chromatography and identified by microelectrospray mass spectrometry. Peaks of higher intensity were sequenced by tandem mass spectrometry. The identified peptide fragments and the measured molecular mass of factor C protein also confirmed the original sequence of protein, as there was no shift in the open reading frame.

Amino Acid Sequence↗
PubMed1997

Phenotypic heterogeneity of the progeny of Streptomyces griseus conidia.

In order to understand the complex ontogenetical processes, the development of Streptomyces (S.) griseus was applied as a model. The developmental cycle of S. griseus starts and ends as a conidium. In between, coenocytic mycelium develops which, if studied by cytomorphological or biochemical methods, exhibits conspicious heterogeneity. The hyphae develop into young, transient and old vegetative hyphae and different stages of reproductive forms. In developmentally blocked mutants these sequences of events appear mixed in all possible associations. It seems as if the program of development could be divided into several subprograms. The quantitative evaluation of the results show that the individual morphological markers exhibit certain independence from each other realized with a given probability. The conidia of S. griseus are also heterogeneous concerning all morphological and physiological traits examined so far (shape, size, light refraction, staining and shape of nucleoids with Feulgen, methyl green--pyronine, intensity and form of polysaccharide distribution, heat resistance, etc.). Kinetics of the survival curves of two S. griseus strains--a well-sporulating and its developmentally blocked mutant /24/--are different from each other, one has many more heat resistant conidia than the other but the kinetics of the survival curves of the two S. griseus strains indicate that spore populations of both react differently to heat treatment and heat resistance can be modeled by assuming the presence of two independent subpopulations of spores with different heat sensitivity. The emergence of two distinct subpopulations with (possibly) the same genetic make-up is designated: phenotypic segregation. Heat resistance is first of all species specific (genetically determined) but the epigenetic segregation seems to be characteristic of the developmental process. This process can in certain mutants be affected by environmental conditions and more importantly by the so-called autoregulators (A-factor and factor C). Factor C and A-factor are needed to normal development, if their quantity or the time of addition to the culture was not optimal, the quantity of spores decreased.

4-Butyrolactone↗
PubMed1997

Amino acid sequence homology of factor C produced by Streptomyces griseus with regulatory proteins of zinc finger type.

Factor C is a regulatory protein produced by Streptomyces griseus 45H. Factor C-like antigen can be detected in the most diverse species examined. It is also present in human serum with an average of 219.4 U/ml of narrow dispersion. The level of factor C-like antigen shows an increase in the sera of patients with different hepatic disorders (341 U/ml), some values being 3-7 times higher than normal (600-1500 U/ml). Correlation was found between the elevated antigen levels and the amount of the bilirubin in the sera of patients with liver cirrhosis. Amino acid sequence homology was found between factor C and zinc finger motifs of several known DNA binding proteins. In fact, factor C was successfully bound to and eluted from a Zn2+ affinity column. Our data show that factor C is probably a zinc finger type DNA binding protein.

Amino Acid Sequence↗
PubMed1997

A short GC-rich sequence involved in deletion formation of cloned DNA in E. coli.

A spontaneous deletion probably caused by rec A independent recombination between short-direct repeat sequences was observed in pUC19 plasmid carrying a piece of Streptomyces genomic DNA after culturing in liquid medium. The deletion removed an unknown portion of the cloned DNA and the BamHI-EcoRI part of the multiple cloning site with an additional flanking 111 bp from the vector. At the junction a 13 bp GC-rich DNA sequence highly homologous to a known spontaneous deletion hotspot was found.

Base Composition↗
PubMed1997

Idiopathic scoliosis--new surgical methods or search for the reasons.

Idiopathic scoliosis (IS) is a deformity of the spine whose aetiology is unknown despite of extensive clinical and basic research work. The significance of this disease lies in the consequences of a spine deformity (deformation of the chest, compromise of the cardio-pulmonar function, compression of the neurological elements, severe somatic and psychological sufferings). According to statistical data, one third of the idiopathic scoliotic cases progress and need surgical intervention. Cotrel and Dubousset introduced the three dimensional correction surgical method for the treatment of spine deformities in 1983 (CD method). The authors report on the application of the CD method for the treatment of IS from 1991 to date. After the operation of 36 patients they give an account of good results and report on the modifications of the surgical technique on the basis of their experiences. Aware of the late consequences of the surgical treatment of IS the authors started with the investigation of the aetiology of the disease in order to introduce a causal treatment. As for the aetiological background of IS, data on the role of heritable factors were relevant only. They gave a hint to start with studies aimed at the investigation of genetic determinants of the syndrome. I aberration of chromosome #10 [karyotype: inv(10)(p11q26)]. In one of the cases there was a multiple familial occurrence of the syndrome coupled with the same anomaly of the karyotype. The probands' father and grandfather all had the same pattern of scoliotic deformity and the same aberrant karyotype of chromosome #10 was found both in the proband and his father. Preparation of genomial DNA from peripheral blood of the patients was started. Fragment length polymorphism (RFLP) examination with PCR technique using oligonucleotide primers specific for chromosome #10 and for regulatory genes of left-right body assymetry is underway.

Chromosome Aberrations↗
PubMed1995

[Diagnostic errors in symptom-poor hyperthyroidism in the aged].

The diagnosis of hyperthyreoidism manifesting in the elderly meets difficulty in many cases. Lack of some characteristic symptoms observable in younger patients can be misleading. The authors summarize the data of ten clinical cases where the hyperthyreoidism appeared in occult form, reminding rather for heart disease or malignant tumours. The assay of thyroid hormones and the level of antithyreoglobulin and anti-thyreoid peroxidase antibodies was unavoidable in order to establish correct diagnosis. Though the early diagnosis and treatment may enhance the life expectancy of the patients and may considerably decrease the cardial and the consecutive cerebral complications. The authors analyse the reasons and possible pathomechanism of the formation of atypical hyperthyreoidism occurring in the elderly.

Age Factors↗
PubMed1990

Detection and determination of factor C--a regulatory protein--in Streptomyces strains by antiserum and monoclonal antibody.

Rabbit antisera and monoclonal antibodies were raised against factor C, a regulatory protein of Streptomyces griseus. ELISA and immunoblotting techniques suitable to determine and characterize factor C antigen was detected in all the 23 Streptomyces strains and variants examined thus far and in one Bacillus subtilis too. Depending on the strain analysed it has a molecular mass of 34,000 or 70,000 in mycelial homogenates. Most of factor C was found excreted into the cultivation medium. The quantity of factor C antigen in different Streptomyces strains showed great variation. Amy+ strains were usually good producers of factor C while Amy- were not. This was consistent with our assumption that factor C was an inducer of reproductive phase in Streptomyces.

Animals↗
PubMed1982

In vivo studies on the age-dependent decrease of the rates of total and mRNA synthesis in the brain cortex of rats.

The membrane hypothesis of aging (Zs.-Nagy, I., 1978, J. Theor. Biol. 75, 189-195) attributes the primary role in cellular aging to an age-dependent decrease of the passive potassium permeability of the cell membrane which is due most probably to free-radical damage of the membrane components. As a consequence, the intracellular and intranuclear ionic strength increases resulting in a condensation of the chromatin and a slowing down of the synthetic processes performed by the nucleus. In this concept it was of importance to reveal whether the rates of total and mRNA synthesis display any age-dependent alteration parallel with the change of membrane permeability of the brain nerve cells. Experiments were performed using tritiated uridine incorporation measurements and suitable preparation techniques in young, adult and old rats (1.5, 13 and 25 mth of age, respectively). Comparisons of the incorporation rates revealed a very considerable decrease in the rate of synthesis of both the total and polyadenylated RNA (polyA + RNA) between the ages of 13 and 26 mth. The old animals displayed only about 55 and 67% of the rate of synthesis for the 2 classes of RNA, respectively, as compared to the young and adult rats, if the results are expressed as dpm/mg RNA. However, the decreases are even more pronounced (34 and 41%) if the results are expressed on a dry weight basis. The results obtained are compatible with the membrane hypothesis of aging.

Aging↗
PubMed1982

Protein phosphatase activity in cell nuclei of rat liver and its relationship to the protein phosphatase in the cytoplasm.

Nuclear protein phosphatase (phosphoprotein phosphohydrolase, EC. 3.1.3.16, abbreviated: NPPase) was extracted from rat liver cell nuclei and subnuclear fractions under different conditions. NPPase activity proved to be strongly bound to chromatin and its presence cannot be explained by an incomplete removal of the cytoplasm from nuclear preparations. The small extent of activation of NPPase after treatment with ethanol or mercaptoethanol suggests that NPPase is present in the nucleus in its activated form. On the other hand, cytoplasmic protein phosphatase (abbreviated: NPPase) from rat liver also showed only a small extent of activation after precipitation with ammonium sulphate or ethanol. Therefore, the pronounced activation of cytoplasmic PPase, which has been observed in rabbit liver and skeletal muscle, cannot be used for differentiation between cytoplasmic and nuclear PPases in rat liver.

Animals↗
PubMed1977

Age-dependent alterations of the rate of RNA synthesis in rat brain cell nuclei.

Endogenous Mn2+ and Mg2+ activated RNA polymerase activity was measured in isolated cell nuclei of brain from rats of different age-groups. It was established that the activity of the nucleoplasmic RNA polymerase is maintained at the level of young animals up to an age of 16 months but is decreased after 24 months. The nucleolar RNA polymerase activity decreases already at 16 months and a higher ratio of the Mn2+:Mg2+ activated RNA polymerase activities has been found to be characteristic for the older animals. By means of stepwise sucrose density gradient centrifugation fractions were obtained from the nuclear preparations highly enriched in cell nuclei of neuronal and glial origin respectively. By measuring the activity of the nucleoplasmic and nucleolar RNA polymerases in these fractions it was found that the elevated ratio of the nucleoplasmic to nucleolar RNA polymerase activity at 16 months of age is a characteristic of the neuronal nuclei while the glial nuclei behave by the opposite manner. A parallelism existing between the age-dependent change of the endogenous RNA polymerase activity and that of perichromatic granules of rat brain cortical cells is discussed.

Age Factors↗
PubMed1976

Some characteristics of phosphorylation and dephosphorylation of proteins of isolated rat liver nuclei.

The phosphorylation and dephosphorylation reactions of the proteins of isolated rat liver nuclei were examined in the presence of ATP. It was shown that the plateau value of the phosphorus incorporation at high concentrations of ATP is the result of an equilibrium of phosphorylation and dephosphorylation. The data of 32P-labelling experiments and those of chemical determination of net change of phosphorus content were compared. The activity of an efficient protein phosphatase in rat liver nuclei is demonstrated. It was shown that the pool of protein-phosphorus in the nuclei is heterogeneous as regards its turnover rate. A protein-phosphorus fraction of high turnover dominates the picture of phosphorylation and dephosphorylation reactions when studied with [gamma-32P] ATP in vitro.

Adenosine Triphosphate↗