A New Report of Multiple Sex Chromosome System in the Order Gymnotiformes (Pisces)

Autor:	Alejandro Laudicina, Sebastián Sánchez, Lilian C Jorge
Rok vydání:	2004
Předmět:	Genetics Autosome Robertsonian translocation Chromosome Cell Biology Plant Science Biology medicine.disease_cause biology.organism_classification Centromere medicine Constitutive heterochromatin Animal Science and Zoology Gymnotus Small supernumerary marker chromosome X chromosome
Zdroj:	CYTOLOGIA. 69:155-160
ISSN:	1348-7019 0011-4545
DOI:	10.1508/cytologia.69.155
Popis:	An X1X2Y sex chromosome system is reported for the first time in Gymnotus sp. The chromosome number observed was 2n=40 (14 M-SM+26 ST-A) in females and 2n=39 (15 M-SM+24 ST-A) in males, with the same fundamental number in both sexes (FN=54). The multiple sex chromosome system might have been originated by a Robertsonian translocation of an ancestral acrocentric Y-chromosome with an acrocentric autosome, resulting in a metacentric neo-Y chromosome observed in males. Single NORs were detected on the short arm of a middle-sized acrocentric chromosome pair. Constitutive heterochromatin was observed in the pericentromeric regions of several chromosome pairs, including the neo-Y chromosome and the NOR carrier chromosomes. The DAPI/CMA3 stain revealed that all the pericentromeric heterochromatin are A+T rich whereas the NORs were associated with G+C rich base composition. The possible ancestral condition characterized by an undifferentiated Y- chromosome from all the Gymnotiformes fishes is discussed.
Databáze:	OpenAIRE
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