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  • 1
    Electronic Resource
    Electronic Resource
    Evolution of thedec-1 eggshell locus inDrosophila. II. Intraspecific DNA sequence analysis reveals length mutations in a repetitive region inD. melanogaster (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 536-544 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; dec-1 eggshell gene ; Wild-type variants ; Repeated region ; DNA sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thedec-1 eggshell gene inDrosophila melanogaster encodes follicle cell proteins required for proper eggshell assembly. As shown by Southern and Northern analyses thedec-1 gene occurs in four alleles (Fcl-4) among wild-type strains. Its second exon has a distinct feature in the form of 12 repeats with 78–91 nucleotides; the first five show nearly 100% homology. DNA sequence comparison of the repeated region of the alleles revealed that the length polymorphisms are caused by changes in the numbers of the first five repeats. The results suggest that the alleles have been generated by unequal intragenic crossing-over and/or slippage during DNA replication and that the allelic length variants have arisen independently. The possiblilty that the most common allele,FC1, has a selective advantage over the other alleles is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556358
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  • 2
    Electronic Resource
    Electronic Resource
    Evolution of thedec-1 eggshell locus inDrosophila. I. Restriction site mapping and limited sequence comparison in themelanogaster species subgroup (1991)
    Springer
    Journal of molecular evolution 33 (1991), S. 321-331 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; dec-1 locus ; Restriction map conservation ; Sequence comparison ; Melanogaster species subgroup ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed ∼18 kb of DNA in and upstream of thedefective chorion-1 (dec-1) locus of the eight known species of themelanogaster species subgroup ofDrosophila. The restriction maps ofD. simulans, D. mauritiana, D. sechellia, D. erecta, andD. orena are shown to have basically the restriction map ofD. melanogaster, whereas the maps ofD. teissieri andD. yakuba were more difficult to align. However, the basic amount of DNA and sequence arrangement appear to have been conserved in these species. A small deletion of varying length (65–200 bp) is found in a repeated sequence of the central transcribed region ofD. melanogaster, D. simulans, andD. erecta. Restriction site mapping indicated that thedec-1 gene is highly conserved in themelanogaster species subgroup. However, sequence comparison revealed that the amount of nucleotide and amino acid substitution in the repeated region is much larger than in the 5′ translated region. The 5′ flanking region showed noticeable restriction site polymorphisms between species. Based on calculations from the restriction maps a dendrogram was derived that supports earlier published phylogenetic relationships within themelanogaster species subgroup except that theerecta-orena pair is placed closer to themelanogaster complex than toD. teissieri andD. yakuba.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102863
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  • 3
    Electronic Resource
    Electronic Resource
    Immunohistochemical Analysis of Steroid 5α-Reductase Type 1 in Human Scalp and Prostate (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 784 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb16225.x
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  • 4
    Electronic Resource
    Electronic Resource
    Deletion of steroid 5α-reductase 2 gene in male pseudohermaphroditism (1991)
    [s.l.] : Nature Publishing Group
    Nature 354 (1991), S. 159-161 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To isolate cDNAs encoding additional 5a-reductases, a size-fractionated and oriented cDNA library was constructed from human prostate poly(A)+ messenger RNA in a pCMV expression vector5. The size of cDNA pools that could be screened for expression of 5o:-reductase in cultured 293 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/354159a0
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  • 5
    Electronic Resource
    Electronic Resource
    Male pseudohermaphroditism caused by mutations of testicular 17β–hydroxysteroid dehydrogenase 3 (1994)
    [s.l.] : Nature Publishing Group
    Nature genetics 7 (1994), S. 34-39 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Defects in the conversion of androstenedione to testosterone in the fetal testes by the enzyme 17β–hydroxysteroid dehydrogenase (17β–HSD) give rise to genetic males with female external genitalia. We have used expression cloning to isolate cDNAs encoding a microsomal ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/ng0594-34
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  • 6
    Electronic Resource
    Electronic Resource
    Life-history variation in Crepis tectorum (Asteraceae) (1989)
    Springer
    Oecologia 80 (1989), S. 540-545 
    Details
    ISSN: 1432-1939
    Keywords: Crepis tectorum ; Life-history ; r-selection ; K-selection ; Stress adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Populations of the monocarpic plant Crepis tectorum were grown in a series of uniform environments to test the hypothesis that weedy populations are more r-selected than populations from a more natural habitat. Weedy populations exhibited a combination of r- and K-selected traits. The relatively rapid growth, the potential for a summer annual habit, and the relatively high fecundity that characterized at least one of the two weed populations studied were considered as r-selected traits favored in habitats of unpredictable duration. However, high levels of competition from other weedy species or from the crop in arable fields may explain at least some presumably K-selected traits observed in the weedy populations, e.g. relatively large seeds and late flowering in the summer. Results indicated that stress due to abiotic factors (strong winds, desiccation and nutrient deficiency) has been a more important selective factor than r- or K-selection, in non-weedy populations from calcareous grasslands (“alvars”) on the Baltic islands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380079
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  • 7
    Electronic Resource
    Electronic Resource
    Size-dependent pollination efficiency in Anchusa officinalis (Boraginaceae): causes and consequences (1988)
    Springer
    Oecologia 76 (1988), S. 125-130 
    Details
    ISSN: 1432-1939
    Keywords: Anchusa ; pollination efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bumblebees foraging on the self-incompatible Anchusa officinalis fly between near neighbour plants and between near neighbour inflorescences within plants. Although many-flowered plants attracted most bumblebees these plants received fewer visits on a per flower basis than smaller plants, and each bumblebee visited a smaller proportion of the flowers. The calculated effective visitation rate per flower was highest on plants of an intermediate size. If pollen-carryover was assumed to be limited the most efficient plant was predicted to be smaller since the proportion of fertilized flowers per bumblebee visit is expected to decrease further on the largest plants in relation to the total flower number. These predictions were tested by measuring fruit-set in the field. The percentage fruit-set decreased with plant size at all sizes that were investigated. That the most efficient plant was small indicates that pollen-carryover was indeed limited. However, the low percentage fruit-set associated with large size did not present a serious problem since the total estimated seed production per plant still increased with size. Selection favoring smaller plants may be low or absent in Anchusa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379610
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of dolomitic lime on DOC and DON leaching in a forest soil (1999)
    Springer
    Biogeochemistry 47 (1999), S. 297-317 
    Details
    ISSN: 1573-515X
    Keywords: dissolved organic carbon ; dissolved organic nitrogen ; Haplic podzol ; hydrophobic and hydrophilic compounds ; liming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The influence of liming on leaching and distribution of dissolved organic carbon (DOC) and nitrogen (DON) in mineral soil was investigated in a leaching experiment with soil columns. Soil samples from separate horizons (O, A and B horizons) were collected from control and limed plots in a field liming experiment in a spruce forest in southern Sweden. The field liming (0.88 kg m−2) had been carried out 8 years before sampling. To minimize the variation among replicates, soil profiles were reconstructed in the laboratory so that the dry weight was the same for each individual soil horizon regardless of treatment. Two soil column types were used with either the O+A horizons or the O+A+B horizons. One Norway spruce seedling (Picea abies (L.) Karst) was planted in each soil column. Average pH in the leachate water was greater in the limed treatment than in the control treatment (5.0 versus 4.0 for O+A columns and 4.3 versus 3.8 for O+A+B columns). After reaching an approximate steady state, the leaching of DOC was 3–4 times greater from the limed O+A and O+A+B columns than from the corresponding control columns but the leaching of DON increased (3.5 times) only in the limed O+A columns. There was a significant correlation between DOC and DON in the leachates from all columns except for the control O+A+B columns, which indicated a decoupling of DOC and DON retention in the B horizon in the control treatment. This might be explained by a selective adsorption of nitrogen poor hydrophobic compounds (C/N ratio: 32–77) while there was a lower retention of nitrogen rich hydrophilic compounds (C/N ratio: 14–20). Proportionally more hydrophobic compounds were leached from the limed soil compared to the unlimed soil. These hydrophobic compounds also became more enriched in nitrogen after liming so in the limed treatment nitrogen might be adsorbed at nearly the same proportion as carbon, which might explain the fact that there was no decoupling of leached DOC and DON from the B horizon after liming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00992911
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  • 9
    Electronic Resource
    Electronic Resource
    Calcium content of liming material and its effect on sulphur release in a coniferous forest soil (2000)
    Springer
    Biogeochemistry 50 (2000), S. 1-20 
    Details
    ISSN: 1573-515X
    Keywords: calcium content ; DOC ; liming material ; pH ; podsol ; sulphur mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Soil columns with O + A (Experiment I) or Ohorizons (Experiment II) from a Haplic Podsol wereincubated at 15 °C for 368 and 29 + 106 days,respectively. Three types of liming material differingin Ca2+ content, i.e. calcium carbonate(CaCO3), dolomite (CaMg(CO3)2) andmagnesium carbonate (MgCO3), were mixed into theO horizons in equimolar amounts corresponding to 6000kg of CaCO3 per ha. In the limed treatments ofExperiment I, the leaching of dissolved organic carbon(DOC) and the net sulphur mineralization (estimated asaccumulated SO 4 2− leaching corrected forchanges in the soil pools of adsorbed and waterextractable SO 4 2− ) increased with decreasingCa2+ content of the lime and increasing degree oflime dissolution. In relation to the controltreatment, only the MgCO3 treatment resulted ina significantly higher net sulphur mineralization. InExperiment I the net sulphur mineralization was 4.06,1.68, 0.57, and 2.14 mg S in the MgCO3,CaMg(CO3)2, CaCO3 and control treatment,respectively. The accumulated SO 4 2− leachingin Experiment II during the first 29 days was 1.70,0.74 and 0.48 mg S in the MgCO3,CaMg(CO3)2 and control treatment,respectively. In the two experiments there wereconsistently significant positive correlations betweenleached amounts of SO 4 2− and DOC. It wasconcluded that net sulphur mineralization was stronglyconnected to the solubilization of the organic matter(DOC formation) and that pH and/or Ca2+ ionsaffected the net sulphur mineralization through theireffects on organic matter solubility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006355532514
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of dolomitic lime on DOC and DON leaching in a forest soil (1999)
    Springer
    Biogeochemistry 47 (1999), S. 295-315 
    Details
    ISSN: 1573-515X
    Keywords: dissolved organic carbon ; dissolved organic nitrogen ; Haplic podzol ; hydrophobic and hydrophilic compounds ; liming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The influence of liming on leaching and distribution of dissolved organic carbon (DOC) and nitrogen (DON) in mineral soil was investigated in a leaching experiment with soil columns. Soil samples from separate horizons (O, A and B horizons) were collected from control and limed plots in a field liming experiment in a spruce forest in southern Sweden. The field liming (0.88 kg m-2) had been carried out 8 years before sampling. To minimize the variation among replicates, soil profiles were reconstructed in the laboratory so that the dry weight was the same for each individual soil horizon regardless of treatment. Two soil column types were used with either the O+A horizons or the O+A+B horizons. One Norway spruce seedling (Picea abies (L.) Karst) was planted in each soil column. Average pH in the leachate water was greater in the limed treatment than in the control treatment (5.0 versus 4.0 for O+A columns and 4.3 versus 3.8 for O+A+B columns). After reaching an approximate steady state, the leaching of DOC was 3--4 times greater from the limed O+A and O+A+B columns than from the corresponding control columns but the leaching of DON increased (3.5 times) only in the limed O+A columns. There was a significant correlation between DOC and DON in the leachates from all columns except for the control O+A+B columns, which indicated a decoupling of DOC and DON retention in the B horizon in the control treatment. This might be explained by a selective adsorption of nitrogen poor hydrophobic compounds (C/N ratio: 32--77) while there was a lower retention of nitrogen rich hydrophilic compounds (C/N ratio: 14--20). Proportionally more hydrophobic compounds were leached from the limed soil compared to the unlimed soil. These hydrophobic compounds also became more enriched in nitrogen after liming so in the limed treatment nitrogen might be adsorbed at nearly the same proportion as carbon, which might explain the fact that there was no decoupling of leached DOC and DON from the B horizon after liming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006155925844
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