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Abstract
Although copper is an essential micronutrient for poultry that serves as a critical cofactor for many enzymes involved in energy metabolism, the neutralization of free-radicals, tissue development and neuroendocrine function, very little research has been conducted on the proteins involved in cellular absorption and transport of copper in poultry. Based on mammalian research, antioxidant protein 1 (ATOX1), ATPase copper transporting alpha polypeptide (ATP7A), and copper transporter 1 (CTR1), are three critical proteins involved in copper absorption and utilization. The goal of the current research was to determine the mRNA expression of these 3 copper transport proteins in chicken digestive, reproductive, and muscle tissues, and to determine if ileum expression varied in broilers at 0, 14 and 42 days of age. Total RNA was extracted from broiler, broiler breeder hen and broiler breeder rooster tissues. Extracted RNA samples were DNase treated and then prepared for 2-step Real Time RT-PCR analysis for ATOX1, ATP7A, CTR1, and glyceraldehyde 3-phosphate dehydrogenase (control) mRNA expression using TaqMan minor groove binding probes and primers designed for each gene. Expression of ATOX1, ATP7A and CTR1 mRNA was detected in all tissues examined and each was individually expressed equivalently in the duodenum, jejunum and ileum. The expression of CTR1 mRNA was significantly greater (P < 0.05) in ileum tissue of day of hatch broilers than 42 day old broilers. The expression of ATOX1, ATP7A did not differ in ileum samples collected from broilers at day 0, 14 and 42 days of age. In immature testes the expression ATOX1, ATP7A, and CTR1 was significantly greater than in mature testes. Similarly, the mRNA expression of ATP7A and CTR1 was greater in granulosa cells of large white follicles than in granulosa or theca cells of the three largest most mature follicles. The results suggest as previously seen in mammals, that ATOX1, ATP7A and CTR1 play a critical role in the absorption, transport and utilization of copper in chicken tissues. In addition, the results suggest that further research is needed to determine the potential importance of enhanced copper utilization by immature testes and undeveloped follicles relative to mature testes and follicles.