Establishment of a PCR-RFLP assay
Blood was sampled from plumage veins and was stored in tubes containing EDTA
as an anticoagulant. DNA was isolated by a slightly modified standard salting out procedure
described by Miller et al. (1988). Fragments of 400 and 250 bp of the GnRHR and NPY genes,
respectively, were amplified by polymerase chain reaction (PCR) in a total of 25 μL, which
included 1μL pooled DNA, 1 μL each primer (10 μM), 0.5 μL dNTPS (10 mM), 2.5 μL 10X
PCR buffer, and 1 U TaqDNA polymerase, using special primers (Table 1). Cycles applied
were: initial denaturation at 94°C for 5 min; 30 cycles consisting of 60 s at 94°C, 60 s at
59.7°C and 60 s at 72°C for denaturation, annealing and extension steps, respectively; and a
final extension at 72°C for 7 min. PCR products of the GnRHR and NPY genes were digested
by 1 μL Bpu1102I and DarI enzymes, respectively, and electrophoresed on a 2% agarose gel
stained with ethidium bromide.