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  • Enologus oxypygum  (2)
  • heterochromatin  (2)
  • 119Sn Mössbauer spectra  (1)
  • Diplopoda
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  • 1
    ISSN: 1573-6857
    Keywords: chromosomes ; diplopoda ; Enologus oxypygum ; FISH ; heterochromatin ; invertebrate ; rDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present study, somatic metaphase chromosomes of the millipede Enologus oxypygum (Diplopoda: Julida) were hybridized in situ with a sea urchin (Echinodermata) ribosomal probe (prRl4) in order to map major RNA genes (rDNA). Chromosomal preparations were also silver stained (Ag-NOR) to evaluate the rDNA transcriptional activity. Our results indicate that RNA genes are throughout heterochromatin in eight chromosomes involving 1/4 of the total heterochromatin which, in this species, is about 67% of the total DNA. Ag-NOR and FISH patterns were not coincident.
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  • 2
    ISSN: 1573-6849
    Keywords: Acanthopetalum sicanum ; chromosome banding ; Diplopoda ; Enologus oxypygum ; heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For the first time, a conventional analysis of C-banded karyotypes was carried out in two distantly related diplopod species; this revealed an impressive percentage of heterochromatin in both genomes. In Acanthopetalum sicanum (Order Callipodida) (2n = 12), heterochromatin constitutes about 60% of the total DNA in females and 56% in males, whereas in Enologus oxypygum (Order Julida) (2n = 22) it is about 67% in both sexes. Heterochromatin of the two species was found to be similar in base composition (AT rich) and heterochromatin distribution, indicating that it has accumulated in a species-specific manner. Sex-determining mechanisms of the XY type were detected in both A. sicanum and E. oxypygum. In A. sicanum, the Y presented the lowest heterochromatic content of all chromosomes in the karyotype, whereas the X presented the highest.
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  • 3
    ISSN: 0044-2313
    Keywords: Tin complexes ; thiolated ligands ; 119Sn Mössbauer spectra ; molecular dynamics ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zinn(IV)-, Monomethylzinn(IV)- und Dimethylzinn(IV)-Komplexe mit Thiolschwefel- und heterocyclischen Stickstoff-Donatoren: Moleküldynamik und Struktur bei 119Sn-Mössbauer-SpektrenDie Moleküldynamik der Komplexe Sn(SPyN)4 (1), SnCl2(SPyN)2 (2), MeSn(SPy)3 (3), MeSnCl(SPyN)2 (4), Me2Sn(TCy)2 (5), Me2SnCl(TOx) (6) und Me2Sn(TUr) (7) (HSPy = 2-Mercaptopyridin; HSPyN = 2-Mercaptopyrimidin; HTCy = 2-Thiocytosin; HTOx = 8-Thiochinolin; H2TUr = 2-Thiouracil) wurde mit 119Sn-Mössbauer-Spektroskopie bei verschiedenen Temperaturen untersucht. Die Flächen unter den Resonanzlinien wurden als Funktion der Temperatur bestimmt und daraus die Debye-Temperaturen, die cut-off-Frequenzen wie auch die rückstoßfreien Anteile (Lamb-Mössbauer-Faktor) und die mittleren quadratischen Auslenkungen der 119Sn-Atome berechnet. Durch Fingerprintvergleiche auf Grund von Literaturdaten wurden monomere Strukturen den Komplexen (1) bis (4) und (6) zugeordnet, während (5) und (7) an der Grenze monomer eindimensionaler Polymerer liegen. Die Ergebnisse werden auf der Basis bekannter Kristall- und Molekülstrukturen diskutiert. Die Umgebung der Zinnatome wird durch Punktladungsmodell-Berechnungen von Kernquadrupolaufspaltungs-Parametern simuliert; Molekülstrukturen für die Komplexe (5) bis (7), von denen keine Röntgendaten verfügbar sind, werden vorgeschlagen.
    Notes: The molecular dynamics of the complexes Sn(SPyN)4 (1), SnCl2(SPyN)2 (2), MeSn(SPy)3 (3), MeSnCl(SPyN)2 (4), Me2Sn(TCy)2 (5), Me2SnCl(TOx) (6), and Me2Sn(TUr) (7) [HSPy = 2-mercaptopyridine; HSPyN = 2-mercaptopyrimidine; HTCy = 2-thiocytosine; HTOx = 8-thioquinoline; H2TUr = 2-thiouracil] has been investigated by variable temperature 119Sn Mössbauer spectroscopy. The area under the resonant peaks has been determined as function of temperature, from which Debye temperatures and cut-off frequencies, as well as recoil-free fractions (Lamb Mössbauer factor) and mean square displacements of 119Sn, have been calculated. By fingerprint procedures on the basis of literature data, monomeric structures are attributed to complexes (1)-(4) and (6), while (5) and (7) lie in the borderline monomersmonodimensional polymers. The results are discussed on the basis of known crystal and molecular structures. The nature of the environment of tin atoms has been simulated by point-charge model calculations of nuclear quadrupole splitting parameters; molecular structures are proposed for complexes (5)-(7), where no X-ray diffractometric data are available.
    Additional Material: 5 Ill.
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