Extraction of tentative mobile introns in fungal histone genes.

We have identified 305 introns in fungal histone genes. Among the 305 introns, 21 had sequence similarities to introns that have different insertion sites. These 21 introns formed 13 intron-pairs. Nine of the 13 pairs had low similarities (35.3%-47.4%) between the flanking DNA sequences of the introns, suggesting that intron-homing or homologous recombination was rare event in the histone intron distribution. Six of the nine pairs consisted of the introns in the genes encoding the different histone families. On the other hand, four of the 13 pairs had 59.6-76.9% similarities between the flanking DNA sequences and the two intron sizes are similar. These four pairs consisted of the introns in the genes encoding the same histone family. Thus, in this analysis, intron-homings were not detected between the fungal genes encoding different histone families.