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  • Electronic Resource  (15)
  • Chemistry  (9)
  • Allozymes  (4)
  • Dominant markers  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Evolutionary analysis of Pinus densata Masters, a putative Tertiary hybrid (1990)
    Springer
    Theoretical and applied genetics 80 (1990), S. 635-640 
    Details
    ISSN: 1432-2242
    Keywords: Pinus ; Species hybridization ; Allozymes ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allozyme differentiation at 13 loci was studied in populations of Pinus tabulaeformis, P. densata, and P. yunnanensis from China. It was previously suggested that P. densata represents a Tertiary hybrid between P. tabulaeformis and P. yunnanensis. The observed levels of allozyme variation within and among the investigated species were comparable to those of other conifers. P. tabulaeformis differed markedly from P. yunnanensis with respect to allozyme frequencies, while P. densata was intermediate between the two putative parents. There was evidence of homozygote excess in embryos from all investigated species, as compared to Hardy-Weinberg expectations. The observed allozyme composition of P. densata conformed to earlier morphological and molecular evidence indicating hybrid origin of this taxon. It was proposed that fusion of gene pools from P. tabulaeformis and P. yunnanensis has led to adaptive evolution of a new species, P. densata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224223
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular systematics and genetic differentiation of Pinus sylvestris (L.) and P. densiflora (Sieb. et Zucc.) (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 159-165 
    Details
    ISSN: 1432-2242
    Keywords: Allozymes ; Chloroplast DNA ; Introgression ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allozyme variation was examined in 22 populations of Pinus densiflora (Sieb, et Zucc.) and four geographic varieties of P. sylvestris (L.): var ‘lapponica’ (Fries, Hartman), var ‘armena’ (Komarov), var ‘mongolica’ (Litvinov) and var ‘sylvestriformis’ (Takenouchi). In addition, we developed paternal chloroplast (cp) DNA markers that distinguish P. densiflora from var ‘lapponica’, var ‘armena’ and var ‘mongolica’. UPGMA cluster analysis based on Nei's distances between all pairwise combinations of the 22 populations revealed patterns corresponding strictly to geographic origin and taxonomic status. Analysis of allozyme variation in var ‘lapponica’, var ‘armena’ and var ‘mongolica’ demonstrated a high level of intrapopulational variability but a low level of interpopulational differentiation. It appears that the late Pleistocene blending of genetically diverse populations was responsible for the observed variation patterns. The constructed phylogenetic trees also showed late divergence of these three varieties. The var ‘sylvestri formis’ was genetically distinct from the other three P. sylvestris varieties. The genetic distances separating var ‘sylvestriformis’ from P. densiflora and the other taxa lend support to a separate taxonomic status for var ‘sylvestriformis’ and a close relation with P. densiflora. We found that var ‘sylvestriformis’ harbors admixtures of allozymes and cpDNA from both P. sylvestris and P. densiflora, which suggests an introgressive nature of this variety. Levels of intrapopulational variability were similar in P. sylvestris and P. densiflora, but interpopulational differentiation was much higher in P. densiflora. In the constructed phylogenetic trees, populations of this species were characterized by relatively long internode distances and branch lengths. The present results suggest that P. densiflora has a more advanced evolutionary age than P. sylvestris.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222074
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  • 3
    Electronic Resource
    Electronic Resource
    Contrasting patterns of genetic diversity in two tropical pines: Pinus kesiya (Royle ex Gordon) and P. merkusii (Jungh et De Vriese) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 436-441 
    Details
    ISSN: 1432-2242
    Keywords: Pinus ; Allozymes ; Chloroplast DNA ; Genetic variation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied allozyme and chloroplast (cp) DNA variation in natural populations of Pinus kesiya and P. merkusii from Thailand and Vietnam. The results showed striking differences between the two species in the amount and distribution of allozyme variation. P. kesiya harboured considerable allozyme variation and showed weak interpopulational differentiation. In contrast, P. merkmii had very low intrapopulational variability but a high level of interpopulational differentiation. The average Nei's genetic distance separating the two species was exceptionally high (0.701) taking into account their close taxonomic placement in the same subsection Sylvestres. The constructed phylogenetic trees revealed very early divergence of P. kesiya and P. merkusii. The present analysis of cpDNA variation also confirmed the dissimilar character of these two species and was compatible with other evidence indicating the outstanding position of P. merkusii as compared to other Asian members of the subsection Sylvestres. Analysis of cpDNA variation in sympatric populations of P. kesiya and P. merkusii revealed that they are pure representatives of the species in question. This result indicates that despite an overlapping distribution P. kesiya and P. merkusii do not hybridise in nature. We suggest that the distinctive character of P. merkusii is a result of an early separation from other Eurasian pines. Despite spatial proximity, P. kesiya and P. merkusii are kept apart by strong reproductive barriers. The low genetic variability of P. merkusii may be explained by previous bottlenecks, reduced gene flow among populations, and an inbreeding due to small population size and asynchronous flowering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223690
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  • 4
    Electronic Resource
    Electronic Resource
    Contrasting patterns of genetic diversity in two tropical pines: Pinus kesiya (Royle ex Gordon) and P. merkusii (Jungh et De Vriese) (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 436-441 
    Details
    ISSN: 1432-2242
    Keywords: Key words  Pinus ; Allozymes ; Chloroplast DNA ; Genetic variation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract   We studied allozyme and chloroplast (cp) DNA variation in natural populations of Pinus kesiya and P. merkusii from Thailand and Vietnam. The results showed striking differences between the two species in the amount and distribution of allozyme variation. P. kesiya harboured considerable allozyme variation and showed weak interpopulational differentiation. In contrast, P. merkusii had very low intrapopulational variability but a high level of interpopulational differentiation. The average Nei's genetic distance separating the two species was exceptionally high (0.701) taking into account their close taxonomic placement in the same subsection Sylvestres. The constructed phylogenetic trees revealed very early divergence of P. kesiya and P. merkusii. The present analysis of cpDNA variation also confirmed the dissimilar character of these two species and was compatible with other evidence indicating the outstanding position of P. merkusii as compared to other Asian members of the subsection Sylvestres. Analysis of cpDNA variation in sympatric populations of P. kesiya and P. merkusii revealed that they are pure representatives of the species in question. This result indicates that despite an overlapping distribution P. kesiya and P. merkusii do not hybridise in nature. We suggest that the distinctive character of P. merkusii is a result of an early separation from other Eurasian pines. Despite spatial proximity, P. kesiya and P. merkusii are kept apart by strong reproductive barriers. The low genetic variability of P. merkusii may be explained by previous bottlenecks, reduced gene flow among populations, and an inbreeding due to small population size and asynchronous flowering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050146
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  • 5
    Electronic Resource
    Electronic Resource
    TransgenicArabidopsis tester lines with dominant marker genes (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 365-372 
    Details
    ISSN: 1617-4623
    Keywords: Arabidopsis thaliana ; Dominant markers ; Map-based cloning ; Recombinant selection ; T-DNA localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The map positions of a set of eight T-DNA insertions in theArabidopsis genome have been determined by using closely linked visible markers. The insertions are dispersed over four of the five chromosomes. Each T-DNA insert contains one or more of the chimeric marker genes neomycin phosphotransferase (neo), hygromycin phosphotransferase (hpt), phosphinothricin acetyltransferase (bar),β-glucuronidase (gusA) and indole-3-acetamide hydrolase (iaaH). Theneo, hpt andbar marker genes are dominant in a selective germination assay or when used as DNA markers in a polymerase chain reaction. These dominant markers will allow recombinants to be discerned in a germinating F2 population, one generation earlier than with a conventional recessive marker. The transgenic marker lines will speed up and simplify the isolation of recombinants in small genetic intervals, a rate-limiting step in positional cloning strategies. The transgenic lines containing thehpt marker will also be of interest for the isolation of deletion mutants at the T-DNA integration sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02172528
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  • 6
    Electronic Resource
    Electronic Resource
    Transgenic Arabidopsis tester lines with dominant marker genes (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 365-372 
    Details
    ISSN: 1617-4623
    Keywords: Key words Arabidopsis thaliana ; Dominant markers ; Map-based cloning ; Recombinant selection ; T-DNA localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The map positions of a set of eight T-DNA insertions in the Arabidopsis genome have been determined by using closely linked visible markers. The insertions are dispersed over four of the five chromosomes. Each T-DNA insert contains one or more of the chimeric marker genes neomycin phosphotransferase (neo), hygromycin phosphotransferase (hpt), phosphinothricin acetyltransferase (bar), β-glucuronidase (gusA) and indole-3-acetamide hydrolase (iaaH). The neo, hpt and bar marker genes are dominant in a selective germination assay or when used as DNA markers in a polymerase chain reaction. These dominant markers will allow recombinants to be discerned in a germinating F2 population, one generation earlier than with a conventional recessive marker. The transgenic marker lines will speed up and simplify the isolation of recombinants in small genetic intervals, a rate-limiting step in positional cloning strategies. The transgenic lines containing the hpt marker will also be of interest for the isolation of deletion mutants at the T-DNA integration sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02172528
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  • 7
    Electronic Resource
    Electronic Resource
    Extrudate roughness of high-density polyethylene and linear low-density polyethylene: Determination of key parameters using screening design (1994)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 1047-1055 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A screening design is used to establish the contribution of various parameters to the roughness of cylindrical extrudates. A dimensionless response variable is proposed to characterize the extrudate roughness, and the effects of ten parameters on this roughness response were examined. Two polyethylenes (one high density and one linear low density) were investigated using a 45 mm single screw extruder. The results show that the main parameters affecting the extrudate roughness are, in order of importance, apparent shear stress at the die wall, die diameter, ratio of die length to diameter, and type of polymer. The other six parameters (the use of an additive, recycling, type of entrance adapter, die material, die temperature, melt temperature) were found to have a non-significant contribution to roughness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760341303
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  • 8
    Electronic Resource
    Electronic Resource
    On the gel effect in the presence of a chain transfer agent in methyl methacrylate polymerization and its copolymerization with various acrylates (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 2179-2188 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of methyl methacrylate (MMA) polymerization, and of its copolymerization with various acrylates, at high conversions in the presence of a chain transfer agent, are investigated with a dilatometer over the entire course of reaction. The displacement to higher conversions of the onset of the gel effect in the MMA homopolymerization, in the presence of a chain transfer agent, was determined. Similar information is also provided for the MMA-acrylate copolymerization systems. An increase in polymerization temperature slightly delays the onset of the gel effect in the MMA-acrylate copolymerization, but considerably increases the final conversion. The final conversion in copolymerization for a constant concentration of the chain transfer agent is independent of the initiator concentration, but is a function of the polymerization temperature. The reaction time for reaching the limiting conversion in copolymerization is increased with an increasing amount of the second monomer, as well as with an increasing number of carbon atoms in the acrylate used as the second monomer. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070491214
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  • 9
    Electronic Resource
    Electronic Resource
    Convective wall-to-suspension heat transfer in circulating fluidized bed risers (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2112-2117 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mechanistic model, which incorporates recent findings on the fluid dynamics in the riser of the circulating fluidized bed (CFB), is developed for predicting the suspension-to-wall heat-transfer coefficient in the riser. It is assumed that heat transfer between the gas-particle suspension and the riser wall takes place by the contact of both particle packets and an emulsion phase on the wall. A characteristic length (L), that is, a sliding distance of the emulsion phase along the heat-transfer surface, is introduced in the model, enabling the effect of the length of heat-transfer surface to be evaluated. It is found that the heat-transfer coefficient decreases with increasing L, but becomes increasingly insensitive to L when L is larger than 1 m. Agreement between model prediction and measurement is encouraging over a range of operating conditions, heat-transfer surface length, and riser diameters.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420803
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  • 10
    Electronic Resource
    Electronic Resource
    Lipase immobilized on hydrophobic porous polymer supports prepared by concentrated emulsion polymerization and their activity in the hydrolysis of triacylglycerides (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 821-828 
    Details
    ISSN: 0006-3592
    Keywords: lipase ; polymer supports ; emulsion polymerization ; immobilized enzyme ; hydrolysis ; triacylglycerides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microporous polymer supports for the immobilization of lipase have been prepared by the polymerization of a concentrated emulsion precursor. The concentrated emulsion consists of a mixture of styrene and divinyl-benzene containing a suitable surfactant and an initiator as the continuous phase and water as the dispersed phase. The volume fraction of the latter phase was greater than 0.74, which is the volume fraction of the dispersed phase for the most compact arrangement of spheres of equal radius. The lipase from Candida rugosa has been immobilized on the internal surface of the hydrophobic microporous poly(styrene-divinyl benzene) supports and used as biocatalysts for the hydrolysis of triacylglycerides. The effects of the amount of surfactant, of the molar ratio of divinylbenzene/styrene in the continuous phase, and of the aquaphilicity of the supports on the adsorption, activity, and stability of the immobilized lipase have been investigated. The microporous poly(styrene-divinylbenzene) adsorbents constitute excellent supports for lipase because both the amount adsorbed is large and the rate of enzymatic reaction per molecule of lipase is higher for the immobilized enzyme than for the free one. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420706
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