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Chromosoma

, Volume 89, Issue 1, pp 42–47 | Cite as

Characterisation of a very complex constitutive heterochromatin in two Gerbillus species (Rodentia)

  • Evani Viegas-Pequignot
  • Touria Benazzou
  • Michelle Prod'Homme
  • Bernard Dutrillaux
Article

Abstract

A large amount of heterochromatin is observed in two species of the genus Gerbillus, G. nigeriae and G. hesperinus. The C-band material represents about one-half of the total karyotype length in the former species, and about one-third in the latter. Several banding techniques and various 5-bromodeoxyuridine (BrdU) treatments were used to characterise these heterochromatic segments. After applying the R-banding technique, three different staining responses of the heterochromatin can be distinguished. In G. nigeriae, strongly stained segments (R-band positive) appear in most chromosomes and, in particular, constitute the short arms of all the larger chromosomes. Palely staining heterochromatic segments (R-band negative) are less abundant in G. nigeriae but predominate in G. hesperinus. In addition, in both species an intermediate staining of heterochromatin is observed near the centromere or in the heterochromatic short arms of some acrocentric and small submetacentric chromosomes. Very short BrdU treatment during the end of the last cell cycle results in asymmetrical staining of chromatids in heterochromatic segments after applying the acridine orange or FPG (fluorescence plus Giemsa) technique. The alternating location of strongly staining segments in one or the other chromatid simulates sister chromatid exchanges (“pseudo-SCE”). This pattern persists after longer BrdU treatment during different stages of the last cell cycle and is independent of the R-staining properties of the heterochromatin. The lateral asymmetric appearance of the large heterochromatic segments in Gerbillus is interpreted as reflecting an uneven distribution of adenine and thymidine between the two strands of DNA.

Keywords

Acridine Sister Chromatid Acridine Orange Sister Chromatid Exchange Constitutive Heterochromatin 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Evani Viegas-Pequignot
    • 1
    • 2
  • Touria Benazzou
    • 3
  • Michelle Prod'Homme
    • 2
  • Bernard Dutrillaux
    • 1
    • 2
  1. 1.CNRS (ER 264) 15Paris Cedex 06France
  2. 2.Département de ProtectionCommissariat à l'Energie Atomique, Laboratoire de MutagenèseFontenay aux RosesFrance
  3. 3.Faculté de Sciences, Département de BiologieUniversité Mohamed VRabatMorocco

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