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Karyological analysis and identification of heterochromosomes in experimental gynogenetic offspring of rainbow trout (Oncorhynchus mykiss, Walbaum)

N. Colihueque^I; P. Iturra^I; N. Díaz^II; A. Veloso^II; F. Estay^II

^IDepartamento de Biologia Celular y Genética, Facultad de Medicina, Universidad de Chile, Casilla 70061, Santiago 7, Chile. Send correspondence to P.I.
^IIDepartamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago 7, Chile

ABSTRACT

Experimental Oncorhynchus mykiss gynogenetic progenies were identified by karyotype analysis. Haploid embryoes were obtained by fertilizing eggs with 10 min irradiated UV sperm. Diploid gynogenetic embryoes obtained by temperature shock showed two X chromosomes, identified with Hoechst 33258/AMD fluorescent stain. Mean survival rate of diploidized embryoes was 37% at hatching. Chromosome number variability in the haploid embryoes suggests Robertsonian chromosome rearrangements in the maternal germ cell line, which can explain previously reported chromosome number polymorphisms in rainbow trout.

Keywords: Karyological analysis; Heterochromosomes; Rainbow trout; Oncorhynchus mykiss.

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