In:
Cytogenetic and Genome Research, S. Karger AG, Vol. 151, No. 3 ( 2017), p. 151-160
Kurzfassung:
Here, for the first time, we describe the karyotype of 〈 i 〉 Myiopsitta monachus 〈 /i 〉 (Psittacidae, Arini). We found 2n = 48, corresponding to the lowest diploid number observed in Neotropical Psittaciformes so far, with an uncommonly large W chromosome homomorphic to the Z. In order to better understand the evolution of the sex chromosomes in this species, we applied several molecular cytogenetic approaches, including C-banding, FISH mapping of repetitive DNAs (several microsatellite repeats), and whole-chromosome painting on metaphases of 〈 i 〉 M. monachus 〈 /i 〉 . For comparison, another species belonging to the same tribe but with a smaller W chromosome (A. aestiva) was also analyzed. The results show that the constitutive heterochromatin has a very diverse distribution pattern in these species revealing heterochromatic blocks in the centromeric region of all chromosomes and in most of the length of the W chromosome in 〈 i 〉 A. aestiva 〈 /i 〉 , while in 〈 i 〉 M. monachus 〈 /i 〉 they were found in interstitial and telomeric regions. Concerning the microsatellites, only the sequence (CG) 〈 sub 〉 n 〈 /sub 〉 produced signals on the W chromosome of 〈 i 〉 A 〈 /i 〉 . 〈 i 〉 aestiva 〈 /i 〉 , in the distal region of both arms. However, in 〈 i 〉 M. monachus 〈 /i 〉 , (CAA) 〈 sub 〉 n 〈 /sub 〉 , (CAG) 〈 sub 〉 n 〈 /sub 〉 , and (CG) 〈 sub 〉 n 〈 /sub 〉 probes were accumulated on the W chromosome, and, in addition, the sequence (CAG) 〈 sub 〉 n 〈 /sub 〉 also hybridized to heterochromatic regions in macrochromosomes, as well as in microchromosomes. Based on these results, we suggest that the increase in length of the W chromosome in 〈 i 〉 M. monachus 〈 /i 〉 is due to the amplification of repetitive elements, which highlights their significant role in the evolutionary process of sex chromosome differentiation.
Materialart:
Online-Ressource
ISSN:
1424-8581
,
1424-859X
Sprache:
Englisch
Verlag:
S. Karger AG
Publikationsdatum:
2017
ZDB Id:
2061918-2
SSG:
12
