It has been shown that POU domain genes play critical roles in the development of the nervous system. We have obtained a new member of the class III POU domain genes, qBrn-1, from the cDNA library of embryonic day 5 quail and have made an extensive expression pattern analysis of qBrn-1 and qBrn-2 throughout the early embryonic development by in situ hybridization. With a specific antibody we prepared, further analysis by immunohistochemistry showed that the location of qBrn-1 protein was consistent with that of the transcripts in the early developing quail. Our results showed that both qBrn-1 and qBrn-2 were preferentially expressed in the developing central nervous system, and their transcripts were initially detected in the neural plate and later in the distinct regions of the neural tube with a stage-dependent pattern. Moreover, their expression was also detected in both notochord and neural crests. However, qBrn-1 signal, different from qBrn-2, was more widely found in the auditory pits, branchial arches, and in the mesodermal components of the developing kidney. And the expression of qBrn-1 in nephric region was earlier and wider than that of mouse Brn-1, suggesting the characteristic function of qBrn-1 in the kidney formation. The distinct dynamic expression patterns of qBrn-1 and qBrn-2 indicate multiple roles of the class III POU genes in quail neurogenesis and organogenesis.

Abstract:The transcription factor Brn-1, which belongs to POU-domain family, has been shown to play critical roles in the development of the nervous system. A cDNA clone coding for a quail Brn-1 homologue, qBrn-1, was isolated. To investigate whether this gene plays a role in the development of the quail nervous system, an anti-N-terminal peptide antibody was prepared. The coding region for amino acids 1-79 (the N-terminal domain of qBrn-1) was subcloned into Trx fusion expression vector pET32c and introduced into the Escherichia coli Origami(DE3) cells for efficient expression. After purification, Trx-fused polypeptides, called Trx-qBrn-1N, were used to immunize the rabbits to prepare polyclonal antibodies against qBrn-1. The produced and purified antiserum showed specificity not only to the in vitro expressed qBrn-1, but also to the natural qBrn-1 in tissues. Immunolabeling on sections by the anti-qBrn-1 serum showed that qBrn-1 was specifically expressed in the developing spinal cord and kidney. This suggests that qBrn-1 may play some roles in the development of avian nervous system and kidney, and the preparation of anti-qBrn-1 polyclonal antibody will facilitate further detection of, and functional study on, qBrn-1 both in vivo and in vitro.