Structure, mRNA expression and linkage mapping of the brain-type fatty acid-binding protein gene (fabp7) from zebrafish (Danio rerio)

The brain fatty acid-binding protein (B-FABP) is involved in brain development and adult neurogenesis. We have determined the sequence of the gene encoding the B-FABP in zebrafish. The zebrafish B-FABP gene spans 2370 bp and contains four exons interrupted by three introns. The coding sequence of zebrafish B-FABP gene is identical to its cDNA sequence and the coding capacity of each exon is the same as that for the human and mouse B-FABP genes. A 1249 bp sequence 5′ upstream of exon 1 of the zebrafish B-FABP gene was cloned and sequenced. Several brain development/ growth-associated transcription factor binding elements, including POU-domain binding elements and the proposed lipogenic-associated transcription factor NF-Y elements, were found within the 5′ region of the B-FABP gene. RT-PCR analysis using mRNA extracted from different tissues of adult zebrafish demonstrated that the zebrafish B-FABP mRNA was predominant in brain with lower levels in liver, testis and intestine, but not in ovary, skin, heart, kidney and muscle. Quantitative RT-PCR revealed a similar tissue-specific distribution for zebrafish B-FABP mRNA except that very low levels of B-FABP mRNA, normalized to β-actin mRNA, were detected in the heart and muscle RNA, but not in liver RNA. Zebrafish B-FABP mRNA was detected by RT-PCR in embryos beyond 12 h postfertilization, suggesting a correlation of zebrafish B-FABP mRNA expression with early brain development. Radiation hybrid mapping assigned the zebrafish B-FABP gene to linkage group 17. Conserved syntenies of the zebrafish B-FABP gene and the human and mouse orthologous B-FABP genes were observed by comparative genomic analysis.