Scientia Marina, Vol 69, No 4 (2005)

Karyological characterization of Mugil trichodon Poey, 1876 (Pisces: Mugilidae)


https://doi.org/10.3989/scimar.2005.69n4525

Mauro Nirchio
Escuela de Ciencias Aplicadas del Mar, Universidad de Oriente, Venezuela, Bolivarian Republic of

Ernesto Ron
Escuela de Ciencias Aplicadas del Mar, Universidad de Oriente, Venezuela, Bolivarian Republic of

Anna Rita Rosi
Dipartimento di Biologia Animale e dell'Uomo, Università di Roma "La Sapienza", Italy

Abstract


Cytogenetic studies were conducted on Mugil trichodon from Margarita Island, Venezuela. The species showed a karyotype 2n=48 with entirely acrocentric chromosomes (Arm number, NF=48). Chromosomes gradually decreased in size and did not allow a clear distinction of homologues, except for one marker pair, which showed a conspicuous secondary constriction. C-banding showed heterochromatic blocks restricted at the centromeric regions of all the chromosomes. Some were more obvious than others, with the exception of the chromosome pair that had a secondary constriction with entirely heterochromatic short arms. Sequential staining with Giemsa and AgNO3 demonstrated the conspicuous secondary constrictions corresponding to the NORs, and these had significant intraindividual size variations between both homologous chromosomes. The data obtained here support the contention that Mugilidae have a conservative chromosome macrostructure and reinforce the hypothesis that small structural chromosome rearrangements involving active NOR sites are the main cause of the karyotypic diversification seen in this group.

Keywords


karyotype; NOR; C-banding; Mugil trichodon

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