Identification of the major sex-determining region of turbot (Scophthalmus maximus).
Sex determination in fish is a labile character in evolutionary terms. The sex-determining (SD) master gene can differ even between closely related fish species. This group is an interesting model for studying the evolution of the SD region and the gonadal differentiation pathway. The turbot (Scophthalmus maximus) is a flatfish of great commercial value, where a strong sexual dimorphism exists for growth rate. Following a QTL and marker association approach in five families and a natural population, we identified the main SD region of turbot at the proximal end of linkage group (LG) 5, close to the SmaUSC-E30 marker. The refined map of this region suggested that this marker would be 2.6 cM and 1.4 Mb from the putative SD gene. This region appeared mostly undifferentiated between males and females, and no relevant recombination frequency differences were detected between sexes. Comparative genomics of LG5 marker sequences against five model species showed no similarity of this chromosome to the sex chromosomes of medaka, stickleback, and fugu, but suggested a similarity to a sex-associated QTL from Oreochromis spp. The segregation analysis of the closest markers to the SD region demonstrated a ZW/ZZ model of sex determination in turbot. A small proportion of families did not fit perfectly with this model, which suggests that other minor genetic and/or environmental factors are involved in sex determination in this species.
Departamento de Xenética, Universidade de Santiago de Compostela, Facultade de Veterinaria, 27002 Lugo, Spain. paulino.martinez@usc.es
Paulino
P
Martínez
Carmen
C
Bouza
Miguel
M
Hermida
Jesús
J
Fernández
Miguel Angel
MA
Toro
Manuel
M
Vera
Belén
B
Pardo
Adrián
A
Millán
Carlos
C
Fernández
Román
R
Vilas
Ana
A
Viñas
Laura
L
Sánchez
Alicia
A
Felip
Francesc
F
Piferrer
Isabel
I
Ferreiro
Santiago
S
Cabaleiro
D000818:Animals; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D005260:Female; D005412:Flatfishes / Q000235:genetics*; D008040:Genetic Linkage; D005819:Genetic Markers / Q000235:genetics; D023281:Genomics; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics; D012727:Sex Characteristics; D019849:Sex Determination Processes
D005819:Genetic Markers