Characterization of a chromosomal rearrangement responsible for producing "apparent" XY-female fall-run Chinook salmon in California.
Fluorescence in situ hybridization (FISH) was used to identify the X and Y chromosomes of offspring produced by normal and "apparent" XY-female fall-run Chinook salmon (Oncorhynchus tshawytscha) from California. FISH experiments were performed using probes to 2 sex-linked loci, growth hormone pseudogene (GH-Psi), and OtY1, as well as a probe to a sex-linked microsatellite (Omy7INRA). Comparison of FISH staining patterns between the offspring produced by normal and apparent XY-females revealed that the apparent XY-female examined transmitted a "Y-like" chromosome with an attenuated OtY1 and GH-Psi signal to half of its offspring. Segregation analysis of microsatellites derived from rainbow trout (Oncorhynchus mykiss) with respect to phenotypic sex was carried out for 2 normal and 2 apparent XY-female Chinook salmon families. Inheritance patterns of Omy7INRA were consistent with this locus being closely linked to GH-Psi in males and in apparent XY-females carrying the Y-like chromosome. Another microsatellite locus (Omm1077) was closely linked to the primary sex-determining locus (SEX) in males but not to GH-Psi/OtY1 in apparent XY-females. The FISH analyses suggest that apparent XY-female fall-run Chinook salmon in California are not the product of a Y chromosome to autosome translocation. Despite the combined FISH and inheritance analyses, we were unable to differentiate between 2 alternative explanations for apparent XY-females, namely, recombination of markers between the sex chromosomes, or a Y chromosome with a dysfunctional or missing sex-determining region.
Williamson
Kevin S
KS
National Marine Fisheries Service, Northwest Fisheries Science Center, Conservation Biology Division, 2725 Montlake Boulevard East, Seattle, WA 98112, USA. Kevin.williamson@noaa.gov
Phillips
Ruth
R
May
Bernie
B
D000818:Animals; D005075:Biological Evolution; D002140:California; D003433:Crosses, Genetic; D005260:Female; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D018895:Microsatellite Repeats; D012474:Salmon / Q000235:genetics*; D019849:Sex Determination Processes; D014178:Translocation, Genetic; D014960:X Chromosome; D014998:Y Chromosome