GGAGTCTTGCTCTGT-3′, 1-reverse: 5′-CCAGGACCTCAGGAGGCCAGTCA-3′; 2-forward: 5′-AGCGGTGAAACTGAGAGTGCGAGGT-3′, 2-reverse: 5′-GCCACATCGCTGCAGTTTAG-3′. The products were cloned with the ‘TOPO TA cloning kit’ (Invitrogen, Groningen, The Netherlands). After bacterial amplification of the cloned PCR fragments by standard procedures, at least three clones from each sample were sequenced with an automated sequencer (ABI Prism 377,