INVESTIGADORES
PIGOZZI Maria Ines
artículos
Título:
The ZW pairs of two paleognaths birds from two orders show transitional stages of sex chromosome differentiation
Autor/es:
PIGOZZI MI; SOLARI AJ
Revista:
Chromosome Research
Editorial:
SPRINGER
Referencias:
Año: 1999 vol. 7 p. 541 - 551
ISSN:
0967-3849
Resumen:
Pachytene oocytes from the two presumably most primitive orders
(Paleognathae) among living birds were used to study the pairing
behaviour and location of recombination nodules (RNs) in the sex pair.
In the ratite Pterocnemia pennata (Rheiformes), the 42 analyzed ZW pairs
show an average of 2.2 RNs distributed along 80% of the synaptonemal
complex (SC) that covers the long arm of the acrocentric Z and W
chromosomes in this homomorphic sex pair. In the tinamid Rynchotus
rufescens (Tinamiformes), the 60 analyzed ZW pairs show an average of
1.35 RNs distributed along 66% of the SC covering most of the long arms
of this visibly heteromorphic ZW pair. RNs are non-randomly distributed
and show interference in both species, but in the tinamou they are
restricted to a significantly smaller stretch. The discovery of an
intermediate degree in the restriction of RN location, between the
extremes of free recombination along most of the W in ratites and strict
localization of a single RN in Neognath birds, suggests its
relationship with the mechanism of sex chromosome differentiation among
Aves.