Tissue distribution, developmental expression and up-regulation of p8 transcripts on stress in zebrafish

The p8 is a transcription factor with a basic helix-loop-helix motif and a nuclear localization signal. A zebrafish p8 cDNA, which consists of 732 bp and encodes 75 amino acids, was identified in this paper. Sequence alignment showed that the bHLH region of p8 was well-conserved during the evolution. Phylogenetic analysis revealed that zebrafish p8 was close to its homologous protein in frog, together clustering to the clade of vertebrates. The zebrafish p8 mRNA expression levels varied much among the detected adult tissues, with the obvious higher expression in backbone and liver. During embryogenesis, the expression of zebrafish p8 mRNA was in higher levels in cleavage stage, decreased from blastula to segmentation stage, but sharply elevated at hatching stage. Quantitative real-time PCR assay suggested up-regulation expressions of zebrafish p8 on a wide range of cellular stressors such as starvation, temperature, osmotic pressure and pH value, implying an important role of p8 gene in response to stress.