INVESTIGADORES
PIGOZZI Maria Ines
artículos
Título:
Extreme axial equalization and wide distribution of recombination nodules in the primitive ZW pair of Rhea americana (Aves, Ratitae)
Autor/es:
PIGOZZI MI; SOLARI AJ
Revista:
Chromosome Research
Editorial:
SPRINGER
Referencias:
Año: 1997 vol. 5 p. 421 - 428
ISSN:
0967-3849
Resumen:
Pachytene oocytes from the ratite bird Rhea americana were used for
synaptonemal complex analysis with a surface spreading technique and
phosphotungstic acid staining. The ZW bivalent is slightly smaller than
the fourth autosomal bivalent and clearly shows unequal W and Z axes
only in 27% of the bivalents. Most of the ZW pairs are completely
adjusted and thus the W and Z axes are almost equal in length. A sample
of 134 recombination nodules (RNs) from 63 ZW pairs showed a striking
departure of number and location of these nodules compared with those of
carinate birds. The average number of RNs in the ZW pair of R.
americana is 2.13, and the average SC length per RN is 4.2 microm. The
locations of the RNs along most of the long arms of the Z and W are not
random, and the distances between pairs of RNs show interference. Thus,
the pattern of RNs in this mostly euchromatic ZW pair is identical to
that of autosomes. From the present and previous data, it is concluded
that the ZW pair of R. americana is in a primitive stage of chromosomal
differentiation, in which recombination is restricted only in the small
short arm and in the pericentromeric region.