项目申请人及其实验室前期的系列研究发现，中等螯合强度有机锌在肉鸡小肠，尤其是十二指肠中的吸收显著高于无机硫酸锌，但其吸收的分子机制尚不清楚。我们提出假说，即中等螯合强度有机锌可能通过上调肉鸡十二指肠中相关锌转运载体的表达并可能直接参与其转运而更多地被吸收。因此，本项目拟采用体内自然饲喂与体外原代培养肉鸡鸡胚十二指肠上皮细胞吸收模型，并结合基因沉默和过表达技术，研究中等螯合强度有机锌与无机硫酸锌对肉鸡十二指肠静脉及肝门静脉中血浆锌含量、十二指肠锌转运载体(ZnT1、ZnT2、ZnT5、ZnT7和ZIP4) mRNA和蛋白表达水平、正常与关键锌转运载体基因沉默和过表达的原代培养肉鸡鸡胚十二指肠上皮细胞的锌吸收、关键锌转运载体mRNA及蛋白表达水平的影响，以揭示中等螯合强度有机锌在肉鸡十二指肠中吸收的分子机制，为我国肉鸡生产中科学研制和应用高效吸收利用的新型有机锌源饲料添加剂，提供科学试验依据。

Previous series of studies from the applicant’s laboratory have indicated that the absorption of zinc (Zn) from the organic Zn with moderate chelation strength was significantly higher than that of the inorganic Zn as ZnSO4 in the small intestine, especially in the duodenum of broilers. However, the underlying molecular mechanisms of the organic Zn absorption remain unclear. We hypothesized that the organic Zn with moderate chelation strength might up-regulate the expressions of related Zn transporters which might be directly involved in Zn transport, and then could have more Zn absorption in the duodenum of broilers. In the present project, therefore, the in vivo experiment with naturally feeding broilers and the in vitro experiments with primary cultured duodenal epithelial cells of broiler embryos in combination with the gene-silencing and the gene-overexpressing techniques, will be conducted to investigate the effects of supplemental organic Zn with moderate chelation strength and inorganic Zn as ZnSO4 on plasma Zn contents from the duodenal vein and the hepatic portal vein, mRNA and protein expression levels of Zn transporters (ZnT1, ZnT2, ZnT5, ZnT7 and ZIP4) in the duodenum of broilers as well as Zn absorption and mRNA and protein expression levels of the key Zn transporters in normal and the key Zn transporters-silenced and -overexpressed primary cultured duodenal epithelial cells, so as to elucidate the molecular mechanisms of absorption of the organic Zn with moderate chelation strength in the duodenum of broilers. The outcomes from the present project will provide scientific bases for developing and applying the highly absorbable new organic Zn feed additive in the broiler production.