INVESTIGADORES
PIGOZZI Maria Ines
artículos
Título:
Recombination nodule mapping and chiasma distribution in spermatocytes of the pigeon, Columba livia
Autor/es:
PIGOZZI MI; SOLARI AJ
Revista:
Genome
Editorial:
CNR PRESS
Referencias:
Año: 1999 vol. 312 p. 308 - 314
ISSN:
0831-2796
Resumen:
Pigeon spermatocytes were processed with a drying-down technique and
their synaptonemal complex (SC) complements were analyzed by electron
microscopy. The synaptonemal complex karyotype of the macrobivalents
shows an excellent correspondence with the mitotic karyotype. The number
and distribution of recombination nodules (RNs) were scored in complete
nuclei stained with phosphotungstic acid. The average number of RNs per
nucleus is 64.7. The number of nodules per bivalent shows a clear
linear relationship with SC length in the 10 longest synaptonemal
complexes, while the microbivalents usually bear a single RN. The
location of RNs has a non-random distribution along the largest
synaptonemal complexes, with lower frequencies near kinetochores and
higher frequencies toward the telomeres. The ZZ bivalent is the fourth
in size and shows free recombination, having on average 3.8 RNs. The
mean number of nodules per cell and the mean number of nodules in the
largest bivalents show very good agreement with the corresponding number
of chiasmata scored in metaphase-I spermatocytes. It is concluded that
the recombination nodules provide a good check for reciprocal exchanges
in this and other species of birds. Additionally, a new morphology for
the recombination nodules is presented, consisting of groups of
electron-dense particles measuring 43 nm in diameter.