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Corpus Systématique Animale

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Close karyological kinship between the reptilian suborder serpentes and the class aves

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Springer (journals)
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Mammiferes_v2b_01147, Oiseaux_v2b_01198, Reptiles_v2b_00342
  • Willy Beçak 1,2
  • Maria Luiza Beçak 1,2
  • H. R. S. Nazareth 1,2
  • Susumu Ohno 1,2
  • 1) Section of Genetics, Instituto Butantan, São Paulo, Brasil
  • 2) Department of Biology, City of Hope Medical Center, Duarte, California, USA

In contrast to the situation found in two classes of warm-blooded vertebrates, mammals and birds, the class Reptilia is not uniform with regard to total genetic content; rather, it contains two distinct categories. The close cytological kinship between snakes and birds was revealed. Both are almost identical in total genetic content, which is about 50 per cent that of placental mammals. Both have microchromosomes, as well as Z-chromosomes very similar in absolute size, comprising nearly 10 per cent of the homogametic haploid (AZ) set. This leads to the implication that snakes and birds originated from the same lineage, and that their Z-chromosomes have not changed substantially since the Jurassic period of the Mesozoic era, about 180 million years ago. Within the reptilian suborder Serpentes, the step-by-step differentiation from the primitive ZW pair to the grossly heteromorphic ZW pair could be observed. In the ancient family Boidae, the sex chromosomes were still homomorphic to each other. In the family Colubridae, the beginning of heteromorphism was manifested in two ways. In some species, a pericentric inversion on the W caused it to differ from the Z; in others, duplication of the W occurred. In the family Crotalidae, the W had apparently achieved its very specialized status; it was a distinctly smaller element.

Catégories Science-Metrix
  • 1 - health sciences
  • 2 - biomedical research
  • 3 - developmental biology
Catégories INIST
  • 1 - sciences appliquees, technologies et medecines
  • 2 - sciences biologiques et medicales
  • 3 - sciences biologiques fondamentales et appliquees. psychologie
  • 4 - biologie moleculaire et cellulaire
Catégories Scopus
  • 1 - Health Sciences ; 2 - Medicine ; 3 - Genetics(clinical)
  • 1 - Life Sciences ; 2 - Biochemistry, Genetics and Molecular Biology ; 3 - Genetics
Catégories WoS
  • 1 - science ; 2 - genetics & heredity
  • 1 - science ; 2 - biochemistry & molecular biology
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Score qualité du texte
  • Mammiferes
  • Oiseaux
  • Reptiles
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