INVESTIGADORES
PIGOZZI Maria Ines
artículos
Título:
Germ cell restriction and regular transmission of an accesory chromosome that mimics a sex body in the zebra finch, Taeniopygia guttata
Autor/es:
PIGOZZI MI; SOLARI AJ
Revista:
Chromosome Research
Editorial:
SPRINGER
Referencias:
Año: 1998 vol. 6 p. 105 - 113
ISSN:
0967-3849
Resumen:
Mitotic and meiotic analysis with light and electron microscopy was
performed in male and female zebra finches (Taeniopygia guttata).
Somatic cells from bone marrow have a 2n = 80 and show the usual sex
chromosome mechanism of birds ZZ (male)/ZW (female). In the germ lines
of both sexes, a single accessory chromosome was regularly present in
all the cells examined from all the individual birds. In synaptonemal
complex (SC) spreads of pachytene oocytes and spermatocytes, this
accessory chromosome forms a single axis, but it behaves differentially
in male and female meiosis. While this accessory chromosome is
euchromatic in oocytes, it is strongly heterochromatic in spermatocytes.
In pachytene spermatocytes, the accessory chromosome adopts a
morphology strikingly similar to that of the XY body ('sex vesicle') of
mammalian spermatocytes. This accessory chromosome is eliminated during
male meiosis and forms a cytoplasmic dense body in young spermatids that
shows strong fluorescence with DAPI. The presence of this germ
line-restricted chromosome does not affect the behaviour of the ZW pair
in oocytes, as the sex chromosomes pair regularly and show a localized
recombination nodule. It is suggested that this accessory chromosome has
transcriptional activity during oogenesis, and thus it is regularly
transmitted through preferential segregation during female meiosis.