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- Jensen, K G, et al.
(författare)
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Effects of organotin compounds on mitosis, spindle structure, toxicity and in vitro microtubule assembly.
- 1991
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Ingår i: Mutagenesis. - 0267-8357. ; 6:5, s. 409-16
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Tidskriftsartikel (refereegranskat)abstract
- Di- and tri-methyl, -butyl and phenyl tin, all as chlorides were tested for toxicity and spindle disturbances in V79 Chinese hamster cells and for effects on in vitro assembly of bovine brain tubulin. The V79 cells were treated for 30 min and in general, loss of a stainable spindle could be demonstrated at slightly higher concentrations than c-mitosis. Both these effects were observed at low, non-toxic concentrations. The c-mitotic activity of the compounds was found to increase with increasing lipophilicity and it was best described by a regression on both lipophilicity (partition coefficient octanol/water) and loss of spindle stain. All compounds showed a concentration dependent inhibition of microtubule assembly and all but diphenyltin induced disassembly of preassembled microtubules. An effect on the rate of polymerization was suggested for tributyl- and triphenyltin. The results further indicate that the inhibition of microtubule assembly is through direct interaction with tubulin but does not involve the sulfhydryls of the protein. Thus, the organotins seem to act through two different cooperative mechanisms, inhibition of microtubule assembly and interaction with hydrophobic sites. The latter mechanism might involve Cl-/OH- exchange across cellular membranes. Previous studies have demonstrated chromosomal supercontraction and aneuploidy in human lymphocytes exposed to low concentrations of organotin in vitro and it is suggested that exposure to these compounds may increase the risk of aneuploidy in humans.
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- Moraga, D, et al.
(författare)
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Estramustine-phosphate binds to a tubulin binding domain on microtubule-associated proteins MAP-2 and tau.
- 1992
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Ingår i: Biochimica et biophysica acta. - 0006-3002. ; 1121:1-2, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- Estramustine-phosphate (EMP), a phosphorylated conjugate of estradiol and nor-nitrogen mustard binds to microtubule-associated proteins MAP-2 and tau. It was shown that this estramustine derivative inhibits the binding of the C-terminal tubulin peptide beta-(422-434) to both MAP-2 and tau. This tubulin segment constitutes a main binding domain for these microtubule-associated proteins. Interestingly, estramustine-phosphate interacted with the synthetic tau peptides V187-G204 and V218-G235, representing two major repeats within the conserved microtubule-binding domain on tau and also on MAP-2. This observation was corroborated by the inhibitory effects of estramustine-phosphate on the tau peptide-induced tubulin assembly into microtubules. On the other hand, the nonphosphorylated drug estramustine failed to block the MAP peptide-induced assembly, indicating that the negatively charged phosphate moiety of estramustine-phosphate is of importance for its inhibitory effect. These findings suggest that the molecular sites for the action of estramustine-phosphate are located within the microtubule binding domains on tau and MAP-2.
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- Waara, Sylvia, 1958-, et al.
(författare)
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A cytogenetic and phenotypic characterization of somatic hybrid plants obtained after fusion of two different dihaploid clones of potato (Solatium tuberosum L.)
- 1992
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Ingår i: Theoretical and Applied Genetics. - New York : Springer-Verlag New York. - 0040-5752 .- 1432-2242. ; 85:4, s. 470-479
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Tidskriftsartikel (refereegranskat)abstract
- Somatic hybrid plants of various ploidy levels obtained after chemical fusion between two dihaploid clones of potato Solanum tuberosum L. have been analysed by cytological, morphological and molecular methods. The hybrid nature of tetraploid and hexaploid plants and the genome dosage in hexaploid hybrids were confirmed by Giemsa C-banding. Tetraploid and hexaploid hybrids showed numerical as well as structural chromosome mutations. The latter occurred mainly in the nuclear organizing chromosome. The tetraploid hybrids were more vigorous than the dihaploid parents as demonstrated by an increase in height, enlargement of leaves, increase in the number of internodes, restored potential for flowering and increased tuber yield. The grouping of tetraploid somatic hybrids into various classes on the basis of leaf morphology revealed that plants with a full chromosome complement were more uniform than aneuploids. Many hexaploid somatic hybrids were also more vigorous than the dihaploidparents and could be grouped into two different classes on the basis of floral colour and tuber characteristics, the differences being due to their different dosage of parental genomes. Most of the tetraploid somatic hybrids showed pollen development halted at the tetrad stage as one of the parental clones contained a S. Stoloniferum cytoplasm. However, one tetraploid plant produced pollen grains with high viability. The chloroplast genome in the hybrid plants was determined by RFLP analysis. All of the hybrids had a cpDNA pattern identical to one parent, which contained either S. Tuberosum or S. Stoloniferum cpDNA. A slight preference for S. Tuberosum plastids were observed in hybrid plants. No correlation between pollen development and plastid type could be detected. © 1992 Springer-Verlag.
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- Wallin, M, et al.
(författare)
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Pressurized Circulating Fluid Bed Gasification Reactor
- 1994
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Ingår i: 29th Intersociety Energy Conversion Engineering Conference: August 7-11, 1994, Monterey, CA : a collection of technical papers. - 1563470918 ; , s. 1543-1548
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Konferensbidrag (refereegranskat)
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