Paracentric inversion involving a NOR-bearing chromosome of rainbow trout (Oncorhyncus mykiss): Electron microscopy studies of the synaptonemal complex
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Data
1996-07-01
Autores
Oliveira, C. [UNESP]
Foresti, F. [UNESP]
Rigolino, M. G.
Tabata, Y. A.
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Resumo
Cytogenetic studies conduced on a sample of 19 specimens of rainbow trout (Oncorhyncus mykiss) showed that 6 presented two chromosomes with a single subterminal AgNOR on the short arms and 13 presented one chromosome with a single subterminal Ag-NOR and a second chromosome with two small subterminal Ag-NORs. Synaptonemal complex studies showed the presence of a pairing failure involving the two lateral elements (LEs) of the NOR-bearing chromosomes only in those specimens with two different NOR-bearing chromosomes, suggesting that the chromosomes with two Ag-NORs originated from a paracentric inversion involving a terminal segment of the original NOR-bearing chromosome. A comparative analysis between three normal and three heterozygous fishes suggest that in the latter group the LEs of the NOR-bearing chromosomes initiate the synaptic process in a more delayed manner, the synapsis develops more quickly, and the nucleolus stays associated with chromosomes for a longer time.
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Palavras-chave
Meiosis, NORs, Paracentric inversion, Rainbow trout, Synaptonemal complex
Como citar
Caryologia, v. 49, n. 3-4, p. 335-342, 1996.