University of Alabama at Birmingham, Birmingham. Alabama 31294,. U.S.A.;'L.ILM., N.I.A.I.D., ... OF WHITE-ROT FUNGI TO HEAVY METALS. Jarosz-Wilkdazka ...
Biochemical Society Transactions (2000) Volume 28, part I
A24 17
Origins and evolution of AIDS viruses: estimating the timescale E. Bailes’, F. Gao’, BE. Beer’, V.M. Hinch’, B.H. Hahn’ ‘Institute of Genetics, University of Nottingham, Queens Medical Centre, Nottingham N G 7 2UH. U.K.; 2Departmenrs of Medicine and Mimobiology, University of Alabama at Birmingham, Birmingham. Alabama 31294, U.S.A.;’L.ILM., N.I.A.I.D., N.I.H.. Rockville, Maryland 20852, U.S.A. -I,
Two retroviruses, human immunodeficiency V ~ N S C S types 1 and 2 (HIV-I and HIV-2). cause the acquired immune deficiency syndrome (AIDS). Together with related simian immunodeficiency viruses (SIV), isolated from a number of other primate species, these comprise the primate Ientiviruses. These viruses exhibit an extraordinary degree of sequence diversity and provide an interesting and challenging model system in which to study molecular evolution. Furthermore, the results obtained provide insights into the origins of AIDS, and have important practical implications for understanding and tackling the ongoing AIDS pandemic. The results of phylogenetic studies indicate that HIV-1 and HIV-2 have each originated from multiple transmissions of SIVs, from chimpanzees and sooty mangabeys, respectively. Resolving the time scale of the evolution of these viruses has proved more difficult. On the one hand, molecular clock extrapolations suggest that all primate lentiviruses shared a common ancestor within the last few hundred years. In contrast, several clades of SIVs appear to exhibit host-dependent evolution, consistent with ancestral primates having been infected by SIV hundreds of thousands, or even millions, of years ago. This discrepancy may reflect errors in estimating the true extent of evolutionary distance beween more divergent viruses. More realistic models of sequence evolution, allowing for a heterogeneity of rates across different sites within proteins, lead to much larger estimates of evolutionary distance and so to much deeper time scales for the evolution of the primate lentiviruses.
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Alkali-labile DNA damage photosensitized by Zarylpropionic acids. S. Starrs and R.J.H. Davies, School of Biology and Biochemistry, Queen’s University, Belfast BT9 7BL, Northern Ireland. Several nonsteroidal antiinflammatory drugs, notably the 2-arylpropionic acids, are known to be phototoxic resulting in adverse cutaneous reactions. In this study we examined the ability of three and of these compounds, suprofen (SP), ketoprofen (U) naproxen (NP),to photosensitize the production of alkali-labile cleavage sites in DNA when irradiated at UVB wavelengths (290-320 nm). We utilised DNA sequencing techniques to locate DNA damage in short (34 or 44 bases long) 5‘- or 3’- 32P-endlabelled oligodeoxyribonucleotides. Experiments revealed that chain cleavage. induced by heating with piperidine, occurs almost exclusively at the positions of guanine (G) bases after irradiation with SP. However, the patterns of G-specific damage observed in single-stranded and duplex DNA molecules are different. The uniform attack on G residues in single-stranded oligomers, which is enhanced in D20, suBests the involvement of the highly reactive species singlet oxygen (Type I1 mechanism). The action of the quenchers sodium azide, DABCO, mannitol and superoxide dismutase (SOD) supports this conclusion. Photosensitization of duplex DNA by SP yields lesions that map predominantly to the 5’-G of GG doublets, and to a lesser extent of GA doublets, whereas isolated Gs are resistant to attack. This behaviour is indicative of Type I electron transfer from DNA to the excited sensitizer, possibly accompanied by hole migration. Compared to SP, KP and NP are weaker photosensitizers exhibiting non-specific base cleavage in single-stranded DNA though, in duplex DNA NP shows the 5’-G specificity observed with SP. Involvement of a Type II mechanism is not evident for either of these drugs.
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Characterization of the 67kDa laminin receptor in breast cancer
Elaine Donaldson‘, John Nelson’, William Scott’ and Tom Gardine? School of Biology and Biochemistry’ and the Department of Opthamology2, The Queen’s University of Belfast, Medical Biology Centre, Belfast BT9 7BL, Northern Ireland. The interaction between the high affinity 67kDa laminin receptor (67LR) and the basement membrane protein laminin plays a critical role in metastasis and tumour progression achieving reco-yition as a target for the treatment of such cancers. As much controversy surrounds the identity of 67LR, this study has characterized 67LR inmunolocalization and expression from cultured breast carcinoma cells. lmmunocytochemical staining using an antibody specific for 67LR confirmed a multifunctional role for this protein with an intracellular hnction as a ribosome associated protein and a cell surface role as a membrane receptor. Western Blot analysis hrther substantiated membrane localization with a reduction in 67LR immunoreactivity following sensitivity of the receptor to trypsin treatment. Furthermore mRNA and membrane protein expression levels of 67LR from cells at different stages of confluency provided evidence for the downregulation of the protein as cells approach confluency. The apparent differences in expression between the proliferating phenotype with high receptor expression and quiescent cells with markedly reduced levels may thus be exploited for future therapeutic interventions against proliferative carcinomas.
0 2000 Biochemical Society
THE LEVEL OF GLUTATHIONE AND GSHRELATED ENZYMES AFTER THE EXPOSURE OF WHITE-ROT FUNGI TO HEAVY METALS
Jarosz-Wilkdazka Anna, Malarczyk Elzbieta Department of Biochemistry, Maria Curie-SklodowskaUniverslw, M. CurieSktodowska Place 3, Lublin. Poland
Many classes of fungi have the ability to accumulate from the environment heavy metals, which are known as inhibitors of many enzymes of both primary and secondary metabolic pathways . In the response to the cellular metal stress, intracellular cysteine-rich molecules play a very important role, which sequester metal ions by thiol groups. The are y-tripeptide glutathione (GSH), metallothioneins and phytochelatins. Additionally heavy metals may initiate indirect, damaging mechanisms. Between them the production of free radicals, especially superoxide anions, which are very dangerous for cells due to their participation in the breakdown of biological macromolecules. On the other hand, fungi as aerobic organisms possess protective enzymes and nonenzymatic substances e.g. glutathione, which eliminate these radicals produced during normal metabolism and after the treatment with environmental stresses, including heavy metals. In this work we examined the influence of cadmium chloride on the level of glutathione (GSH and GSSG)in the mycelium of Basidiomycetes, belonging to white-rot fungi. Additionally we investigated the changes in the activities of glutathione reductase (GR) and glutathione peroxidase (GSH-Px), enzymes which were recognized as essential components of the antioxidative systems of the living cells. We show that GSH and enzymes GSH-relatedenzymes may play an important role in the cadmium tolerance in white-rot fungi.
