Identification of the sex of Oriental white stork, Ciconia boyciana, by the polymerase chain reaction based on its sex chromosome-specific DNA sequences.

Southern blotting of HindIII-digested genomic DNAs from the female and male Oriental white stork (Ciconia boyciana) with the EE0.6 probe cloned from the W chromosome of chicken (Gallus domesticus) produced a 3.0-kb W chromosome-derived band specific to the female and a 3.5-kb Z chromosome-derived band common to both sexes. These two genomic fragments were cloned and the counterpart sequences to that of EE0.6 in these fragments, XH0.6 and XH0.6RSM (XH0.6-related sequence in the male), respectively, were subcloned. Nucleotide sequences of XH0.6 and XH0.6RSM showed 92% identity. PCR using a set of primer sequences from XH0.6, which differed several nucleotides from those in XH0.6RSM, amplified an about 300-bp genomic sequence only from the female C. boyciana. This method was applied successfully to identify the sex of individual young birds of C. boyciana, an endangered special natural monument in Japan and whose sexes are unidentifiable from their external morphology.