| Fatty acid binding proteins (FABPs) are a family of proteins involved in the transport of a wide variety of hydrophobic molecules within the cytosol of cells. Tissues with high levels of fatty acid (FA) metabolism such as adipocytes, intestine and liver have a correspondingly high levels of FABPs which correlate to the rate of cellular FA uptake and utilization. Moreover, many of the 11 FABP family members are mainly expressed in a tissue specific manner. For example, FABP6 is predominantly expressed in adult animals in the ileum where it is involved in intracellular transport of bile acids, however it has also been identified in the steroid hormone producing cells of the ovary and adrenal glands in mammals and zebrafish where it may participate in steroid metabolism. Since very few studies have been conducted in aves, the objective of the present study was to determine the tissue and cell specific distribution of FABP6 transcripts and protein through the use of PCR, sequence verification, immunoblotting, and immunohistochemical staining approaches in both female and male chickens and turkey embryos. The purpose of this study is to compose a comparative analysis between FABP6 gene expression in mammals and poultry, and identify the similarities between bile acid and steroid hormone metabolism that may further identify the role of this protein in cellular physiology.;Unlike mammals, FABP6 was not restricted to the distal region of the small intestine, but rather distributed across the intestine with a significant abundance in the ileum in the embryo, broilers, and layers. This was confirmed by immunohistochemical images that have a high reactivity of FABP6 in the epithelium of the ileum, with lower quantities found in the duodenum. This study is the first to identify the presence of FABP6 mRNA and protein in the testis, supporting the proposed overlapping function of FABP6 in bile acid and steroid hormone metabolism. Furthermore, FABP6 was examined in various stages of follicular development, being identified in all phases of follicular development, with the greatest abundance in the small yellow follicles. In mammals, FABP6 was identified strictly in the progesterone producing cells of the luteum; while in chickens FABP6 is found in both the granulosa and theca cells that are not limited to progesterone production. |
