Structural change of a particular H2B histone gene possibly results in differences in its transcriptional regulation in different chicken tissues.

The chicken H2B histone gene family consists of eight highly homologous members (H2B-I to H2B-VIII) belonging to two major histone gene clusters. Seven of these genes have been sequenced and shown to encode three different H2B protein variants. Northern analysis with a probe, which mainly consists of the 5'-flanking region containing the sequence for the mRNA leader of H2B-V encoding a particular H2B protein variant, revealed that the mRNA level transcribed from this particular gene was higher in the kidney than in the oviduct and lung. To elucidate whether the structure of the H2B gene differs in the three different tissues, we analyzed DNAs from the oviduct, lung, and kidney. On Southern analysis, various H2B gene-specific probes hybridized with two particular H2B genes (H2B-IV and H2B-V), which are located in close proximity within a 12 kb EcoRI fragment, from the oviduct and lung with an intensity of about one quarter of that from the kidney. These findings suggest that some difference of DNA structure of the H2B-V gene may result in its relatively higher expression in the kidney.