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  • 1
    Electronic Resource
    Electronic Resource
    Structural constraints in expansion segments from a midge 26S rDNA (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1016-1021 
    Details
    ISSN: 1432-1432
    Keywords: Chironomus ; LSU rRNA evolution ; Expansion segments ; Compensatory mutations ; rRNA processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA sequences representing approximately 40% of the large-subunit rRNA gene from the lower dipteran Chironomus thummi were analyzed. Once aligned with their Drosophila counterparts, sequence and base content comparisons were carried out. Sequence identity was found to be high overall, except for six regions that displayed a local bias in nucleotide composition toward AT. These regions were identified as expansion segments D3, D4, D5, D6, D7a, and D12. Besides base sequence divergence, differences in length were observed between the respective variable domains of the two species, particularly for D7a. Prediction of secondary structure showed that the folding of the Chironomus expansion segments analyzed is in agreement with the general patterns proposed for eukaryotic LSU rRNA. The comparison with Drosophila revealed also that the Chironomus secondary structures of the variable domains are supported by multiple compensatory substitutions or even compensatory insertions. Chironomus D7a displayed an unusual structural feature with respect to the insect D7a models that have been inferred up to now. The structural constraint observed in the expansion segments of Diptera so distantly related as midges and Drosophila suggests that these regions contribute to some functional role. Concerning the D7a of insects so far analyzed, there can be, in addition to a conserved secondary structure, a nucleotide composition constraint that might be important for the process giving rise to the alpha and beta halves of the 26S rRNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173183
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  • 2
    Electronic Resource
    Electronic Resource
    Functional analysis of the 3′-terminal part of the Balbiani ring 2.2 gene by interspecies sequence comparison (1990)
    Springer
    Journal of molecular evolution 31 (1990), S. 221-227 
    Details
    ISSN: 1432-1432
    Keywords: Balbiani rings ; Nucleotide sequence ; 3′ ends ; Repeat units ; Evolutionary conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An interspecies comparison was made between the 3′ ends of Balbiani ring genes fromChironomus. The comparison was focused on the BR2.2 gene, and a part at the 3′ end fromChironomus pallidivittatus (which included also a segment of the gene core) was cloned. Its sequence, and other previously published BR sequences from this species and fromChironomus tentans were used in the analysis. The 3′ parts of these repetitive genes can be divided into a region belonging to the core of the genes followed by a terminal region. In the core region the repeats (each of which consists of a constant part and a subrepeated part) are highly similar and the constant parts show little interspecies differentiation. Furthermore, the two parts of the repeats are units in an evolutionary and probably also functional sense. The terminal region contains modified constant units, usually isolated betwen acidic so-called cys regions, the whole arrangement lying upstream of an intron toward a 3′-terminal exon. Most of the modified constant units are mosaics in rates of evolution with stable outer quarters bordering to equally stable cys regions and a central half with a very high rate of evolution. One of the terminal units, present only in the BR2.2 gene and second from the end, differs distinctly not only from corresponding core units but also from other terminal units in the three normally active BR genes. It lies upstream of all cys regions and is evolutionarily conserved over most of its length. Furthermore, two-dimensional protein structure prediction does not exclude an endoproteolytic cleavage site in this unit. Such a site appears unlikely in other terminal or core regions. This is of interest in view of evidence for intracellular cleavage of the BR2.2 terminal region with liberation of a part containing a DNA-binding domain (Botella et al. 1988). All in all the fine anatomy of evolutionary changes at the BR gene termini shows interesting correlations with postulated functional relations and may have predictive value in the further functional analysis of this part of the gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02109499
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  • 3
    Electronic Resource
    Electronic Resource
    Subrepeats within the BR1β repeat unit inChironomus pallidivittatus can be classified into different types depending on codon usage (1988)
    Springer
    Journal of molecular evolution 27 (1988), S. 298-302 
    Details
    ISSN: 1432-1432
    Keywords: Balbiani rings ; cDNA clones ; Nucleotide sequence ; Repeat units ; Subrepeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new type of repeat unit was isolated from Balbiani ring 1 ofChironomus pallidivittatus and designated, BR1β repeat. It consists of a constant and a subrepeated part, like previously described units belonging to the core blocks of the BR genes. The subrepeated part contains 10-codon subrepeats with an arrangement similar to the subrepeats of the previously described BR2β gene. The present unit differs from earlier reported core units firstly in a much lower number of copies (about 15) per genome, which are tandemly arranged. Secondly, the number of subrepeats per BR1β repeat unit can show great variations. On the basis of the pattern of codon usage, three types of subrepeats can be distinguished. One type lies 5′-proximal in the subrepeat array and consists of variable numbers of subrepeats almost identical at the nucleotide level. The last complete subrepeat represents another type, with consistent differences in codon usage as compared to subrepeats of the proximal type. Finally, there is an intermediate type represented by the subrepeat preceding the distal one. Here, codon characteristics from proximal and distal subrepeats are mixed in a patchy and irregular way. The evolution of the arrays can be understood either as being the result of subrepeat formation in two steps (occurring before and after amplification of whole repeat units) or as the result of a continuous process in which there is evidence for participation of gene conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101191
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  • 4
    Electronic Resource
    Electronic Resource
    A Comparison of the High-Temperature Oxidation of 17Cr-2Ni and 18Cr-8Ni Austenitic Stainless Steels at 973 K (1998)
    Springer
    Oxidation of metals 49 (1998), S. 297-324 
    Details
    ISSN: 1573-4889
    Keywords: AISI 304 ; LOW-NICKEL AUSTENITIC STAINLESS STEEL ; HIGH TEMPERATURE ; HIGH MANGANESE ; ISOTHERMAL AIR OXIDATION
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior in air at 973 K of theaustenitic stainless steels 18Cr8Ni and17Cr-2.5Ni-10.5Mn-2Cu-0.17N (low-nickel content), wasstudied in a thermobalance. The steels were heated fromroom temperature up to 973K at 10 K min-1, oxidizedfor 80 hr and then cooled to room temperature at 80 Kmin-1. The two steels had the same weightgains, 0.18 mg cm-2, which is equivalent tooxidation layers about 1.15 μm theoretical thickness. In both cases, thegeneral shapes of the ΔWS-1 (mgcm-2) curves vs. t (hours) were parabolic,but X-ray diffraction of the oxidized surfaces, surfaceand crosssection optical microscopy and SEM observations and EDSmicroanalysis show important differences betweenthem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018830424480
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  • 5
    Electronic Resource
    Electronic Resource
    Corrosion Protection of Low-Nickel Austenitic Stainless Steel by Yttrium and Erbium-Ion Implantation Against Isothermal Oxidation (2000)
    Springer
    Oxidation of metals 54 (2000), S. 87-101 
    Details
    ISSN: 1573-4889
    Keywords: low-nickel austenitic stainless steel ; high-temperature oxidation ; ion implantation and reactive elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The beneficial effect of ion-implanted yttrium and erbium on the oxidation behavior of low-nickel austenitic stainless steel (LNiSS) at 973 K has been investigated up to 500 hr of oxidation test in air. The resulting oxide scales were examined by a wide range of experimental techniques, including SEM/EDS, XRD, and EPMA. The results indicate that both reactive elements have similar effects. The most significant effects have been to significantly reduce the corrosion rate and to improve the oxide scale adhesion. It is concluded that ion implantation is a powerful tool as surface-modification process introducing reactive elements in the top surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004602729629
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  • 6
    Electronic Resource
    Electronic Resource
    Ku-related antigens are associated with transcriptionally active loci in Chironomus polytene chromosomes (1996)
    Springer
    Chromosoma 105 (1996), S. 150-157 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Antigens of Chironomus reactive with human sera containing anti-Ku antibodies and also with specific antibodies to each Ku subunit were characterized by immunoblot analysis. Three main antigen species were identified in nuclear-enriched extracts from salivary gland cells of Chironomus thummi, ranging in Mr from 55000 to 67000. The nuclear localization of Ku-related antigens in the dipteran Chironomus was studied by immunofluorescent labeling in polytene chromosomes of the salivary glands. Balbiani rings, loci highly active in transcription, were found to be strongly labeled by anti-Ku antibodies. Sugar-induced changes in the activity of the Balbiani ring genes were accompanied by the redistribution of Ku-related antigens as visualized by their absence in regressed Balbiani ring loci, and continued presence only in those that were transcriptionally active. A drastic change in the distribution of Ku-related antigens was also observed when C. thummi larvae underwent heat treatment as the immunofluorescent staining was restricted to previously described heat shock puffs. Anti-Ku sera reacted in addition with several chromosomal bands in which the presence of RNA polymerase II was also immunologically detected. The results show that Chironomus antigens reactive with anti-Ku antibodies are related to transcription in polytene chromosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050170
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  • 7
    Electronic Resource
    Electronic Resource
    Expression of the tomato peroxidase gene TPX1 in NaCl-adapted and unadapted suspension cells (1999)
    Springer
    Plant cell reports 18 (1999), S. 680-683 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsLycopersicon esculentum ; Salt stress ; Peroxidase ; Cell suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression pattern of a peroxidase – (EC 1.11.1.7) encoding gene, TPX1, was studied in NaCl-adapted and unadapted tomato (Lycopersicon esculentum) cells growing in suspension culture. We followed the transcript level during the cell growth cycle and under different salt treatments. There was a cell-cycle-dependent TPX1 expression, the maximum level of transcripts coinciding with the period of cell enlargement in both salt-adapted and unadapted tomato cells. However, enzyme activity of the encoded isoperoxidase was only detected in the culture medium of the salt-adapted cells. NaCl treatment decreased TPX1 transcripts in both cell lines, but the threshold concentration for this down-regulation was higher in adapted cells. In conclusion, salt-adapted tomato cells show significant changes in comparison with unadapted cells in the expression of a gene encoding a cell-wall-targeted peroxidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050642
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  • 8
    Electronic Resource
    Electronic Resource
    Identification of the spI products of Balbiani ring genes in Chironomus thummi (1989)
    Springer
    Chromosoma 98 (1989), S. 428-432 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The spI fraction of high molecular weight secretory proteins was analysed in Chironomus thummi. These proteins are encoded by giant Balbiani ring (BR) genes which develop specifically in salivary gland cells. Each component of the spI fraction was studied electrophoretically from early and middle 4th instar larvae and prepupae, as well from galactose-treated larvae where changes in the relative puffing pattern of BR1 and BR2 are known to occur. The spI fraction consists of at least two bands with electrophoretic mobilities slower than those of the spI components of Camptochironomus. The slow migrating component remains throughout the 4th larval instar, while the amount of the faster component changes, being abundant in early 4th instar and prepupae, but not present (or very weak) in middle 4th instar. The correlated shifts in BR puffing pattern during these developmental stages suggest that the slow and fast components are encoded by BR2 and BR1. The spI fraction is modified by galactose treatment, the fast component being induced in parallel with a decrease in the slow component. These changes are correlated with changes in the steady-state levels of RNA: an increase in BR1 RNA and a decrease in BR2 RNA, and of proteins. These proteins could correspond to the spIb and spIa fractions allocated to BR2 and BR1, respectively, in Camptochironomus. After galactose treatment a new faster band sometimes appears, that could correspond to the spIc fraction of Camptochironomus. A possible spId equivalent was also identified. In conclusion the main features of the spI family in C. thummi are similar to those of spI in Camptochironomus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292788
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  • 9
    Electronic Resource
    Electronic Resource
    P-odd observables at the $\Upsilon$ peak (1999)
    Springer
    The European physical journal 7 (1999), S. 205-215 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study the $\gamma$ -Z interference in the process $e^+ e^-\rightarrow \Upsilon \rightarrow \tau^+ \tau^-$ as a means to measure the neutral current coupling of the b-quark. The helicity amplitudes are calculated from resonant and background diagrams and the spin density matrix of the final state is discussed. The spin analyzer of the $\tau$ 's is illustrated with the decays $\pi \nu$ and $\rho \nu \rightarrow (\pi \pi) \nu$ . With $10^8 \Upsilon$ a sensitivity to $g_V^b$ of a few per cent could be reachable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100529801007
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  • 10
    Electronic Resource
    Electronic Resource
    Paracuaria hispanica n. sp. (Nematoda: Acuariidae), a stomach parasite of the pyrenean desman Galemys pyrenaicus Geoffr. (Insectivora: Talpidae), with a redefinition of the genus Paracuaria Rao, 1951 (1994)
    Springer
    Systematic parasitology 29 (1994), S. 105-112 
    Details
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Adult and fourth-stage larvae of Paracuaria hispanica n. sp., from the stomach of the Pyrenean desman Galemys pyrenaicus Geoffroy (Insectivora: Talpidae) in northern and central Spain, are described. The new species differs from the other members of the genus Paracuaria (P. adunca and P. soricis), among other morphological details, in its smaller body and spicule sizes, the presence of a cuticular ring around the tip of the female tail, and the existence of lateral alae running longitudinally along its body from the cervical region to the tail. In view of the latter feature, the genus Paracuaria is redefined. The fourth stage larva of the new species is distinguished from that of P. adunca by its monocuspid deirids. P. hispanica occurred in 45% of the 20 host specimens examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009806
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