Biomedical subjects

B Piechulla

Publications and source records attributed to B Piechulla.

23 records · Page 2Linked to original sources

PubMed1983

Mitochondrial polypeptide elongation factor EF-Tu of Saccharomyces cerevisiae. Functional and structural homologies to Escherichia coli EF-Tu.

The polypeptide elongation factor EF-Tu was isolated from a mitochondrial 100 000 x g supernatant of the yeast Saccharomyces cerevisiae and purified over 880-fold by DEAE-Sephadex chromatography and gel filtration. The factor efficiently replaces bacterial EF-Tu in a phenylalanine polymerizing cell-free system of Escherichia coli, it binds GDP and it protects phenylalanyl-tRNA against hydrolysis of the ester bond in the presence of 10 mM GTP. The polymerizing activity of the mitochondrial factor is inhibited to 90% by 50 microM N-ethylmaleimide and to 50% by 2.5 microM kirromycin. The purified factor contains two major polypeptides of apparent molecular weights 48 000 and 34 000. Antibodies raised against the 48 000-Mr protein react with EF-TuE. coli, as revealed by immune blotting and by the inhibition of phenylalanine polymerization. No reaction was observed between anti-(34 000-Mr) and 48 000-Mr protein or EF-TuE. coli. The 48 000-Mr protein has the same isoelectric point (pI = 6.2) and a content of cysteine and basic amino acids similar to the bacterial EF-Tu. It is concluded that the 48 000-Mr protein is the analogue to EF-TuE. coli, and that yeast mitochondrial EF-Tu is functionally and structurally more related to bacterial EF-Tu than cytosolic EF-1 of the same cell.

Chemical Phenomena↗

PubMed1983

Consensus structure and evolution of 5S rRNA.

A consensus structure model of 5S rRNA presenting all conserved nucleotides in fixed positions has been deduced from the primary and secondary structure of 71 eubacterial, archaebacterial, eukaryotic cytosolic and organellar molecules. Phylogenetically related groups of molecules are characterized by nucleotide deletions in helices III, IV and V, and by potential base pair interactions in helix IV. The group-specific deletions are correlated with the early branching pattern of a dendrogram calculated from nucleotide substitution data: the first major division separates the group of eubacterial and organellar molecules from a second group containing the common ancestors of archaebacterial and eukaryotic/cytosolic molecules. The earliest diverging branch of the eubacterial/organellar group includes molecules from Thermus thermophilus, T. aquaticus, Rhodospirillum rubrum, Paracoccus denitrificans and wheat mitochondria.

Bacteria↗

PubMed1981

Nucleotide sequence of 5S ribosomal RNA from Aspergillus nidulans and Neurospora crassa.

The nucleotide sequences of 5S rRNA molecules isolated from the cytosol and the mitochondria of the ascomycetes A. nidulans and N. crassa were determined by partial chemical cleavage of 3'-terminally labelled RNA. The sequence identity of the cytosolic and mitochondrial RNA preparations confirms the absence of mitochondrion-specific 5S rRNA in these fungi. The sequences of the two organisms differ in 35 positions, and each sequence differs from yeast 5S rRNA in 44 positions. Both molecules contain the sequence GCUC in place of GAAC or GAUY found in all other 5S rRNAs, indicating that this region is not universally involved in base-pairing to the invariant GTpsiC sequence of tRNAs.

Aspergillus nidulans↗

PubMed1981

Phylogenetic tree derived from bacterial, cytosol and organelle 5S rRNA sequences.

A phylogenetic tree was constructed by computer analysis of 47 completely determined 5S rRNA sequences. The wheat mitochondrial sequence is significantly more related to prokaryotic than to eukaryotic sequences, and its affinity to that of the thermophilic Gram-negative bacterium Thermus aquaticus is comparable to the affinity between Anacystis nidulans and chloroplastic sequences. This strongly supports the idea of an endosymbiotic origin of plant mitochondria. A comparison of the plant cytosol and chloroplast sub-trees suggests a similar rate of nucleotide substitution in nuclear genes and chloroplastic genes. Other features of the tree are a common precursor of protozoa and metazoa, which appears to be more related to the fungal than to the plant protosequence, and an early divergence of the archebacterial sequence (Halobacterium cutirubrum) from the prokaryotic branch.

Bacteria↗

PubMedDate not supplied

Flax-seed extracts with phytoestrogenic effects on a hormone receptor-positive tumour cell line.

UNLABELLED: The higher soy intake in the Asian population compared to Europeans is believed to be an essential factor for the lower incidence of hormone-dependent tumours in Asia. It has already been shown that soya beans, with their ingredients genistein and daidzein from the isoflavonoid group, have protective effects on hormone-caused diseases. Lignans are another, less investigated, group of phytoestrogens. The aim of this study was to investigate the effects of flax-seed, which is typically found in Northern European diets, on the proliferation and hormone production of an estrogen receptor (ER)-positive trophoblast tumour cell line. MATERIALS AND METHODS: Trophoblast tumour cells of the cell line Jeg3 were incubated with 2 different concentrations of the isolated crude extract of flax-seed and 7 chemically partitioned extract fractions. Untreated cells were used as controls. After 48 h of stimulation, cell proliferation was measured using the BrdU method. The concentrations of hCG and progesterone produced by the trophoblast tumour cells were measured 48 h after stimulation. Extract fractions with antiproliferative effects in the BrdU- test were analysed by HPLC-MS. RESULTS: Our study showed an inhibitory influence of some of the isolated flax-seed fractions on the Jeg3 tumour cells. Proliferation of the Jeg3 cells was decreased by flax-seed fractions I, V, VI and VII in a dose-dependent manner. Inhibition of hCG production by flax-seed extracts III, V, VI and VII was also dose-dependent. Extract fractions V and VI decreased the production of progesterone by 58% to 86%. Some extract fractions showed a stimulating effect on hormone production and cell proliferation. HPLC-MS analysis showed the presence of matairesinol and biochanin A in flax-seed fraction VI. DISCUSSION: Flax-seed seems to have similar inhibitory effects to soya on hormone production and proliferation of hormone-sensitive tumour cells. Our results showed a dose-dependent inhibition by isolated flax-seed extracts on the Jeg3 cell line. Matairesinol and biochanin A seem to be useful candidates for extended tests on other tumour cell lines and normal tissues to evaluate the potential benefit of a lignan-containing therapy in hormone-dependent diseases.

Cell Division↗