SEQUENCE CLONING AND EXPRESSION ANALYSIS OF HIRA GENE IN COLOR CRUCIAN CARP CARASSIUS AURATUS

Hir/hira(histone regulation) genes were first identified in yeast Saccharomyces cerevisiae as negative regulators of histone gene expression1 They represent a conserved protein family found in various organisms, including Drosophila, pufferfish,Xenopus, chicken, mouse and human1The HIRA complex in D1melanogaterfulfilled both protamine removal and replication independent deposition of H3132H4 tetramers in the male nucleus after sperm entry, thus making the sperm decondensation and forming male pronucleus to participate in the formation of the diploid zygote1 In order to further analyse the function of hira gene in fish development and in gynogenesis, we cloned a segment of hira gene from colored crucian carp Carassius auratus (named Cahira) which shows high sequence similarity with vertebrate hira genes1 The incomplete genomic sequence of Cahira gene is 2181bp including 6 introns, and the introns length are 118bp, 275bp, 372bp, 84bp, 472bp and 86bp, respectively1 Its opening reading-frame (ORF) is 759bp, and encodes a 253 amino acid peptide1 The peptide derived from the gene sequence contains WD-repeat domains in their amino2terminus, which is consistent with the characteristic of HIRA proteins1 RT2PCR analysis showed that higher level of Cahira mRNA could be detected in ovary and liver, while lower expression level were present in brain, heart, spleen and kidney1 No transcripts were detected in testis and muscle1 This indicates that hira gene may play a definitive role in ovary and liver in colored crucian carp. The cloning of HIRA homologue from this carp and its expression analysis may provide basic documents for further study on the role of hira gene in fishes.