锌通过基质蛋白调控鸭蛋蛋壳结构的作用机制

Eggshell quality is one of the most important economic and apparent properties of duck eggs, and its decreased quality adversely affects the production of laying duck and egg processing industries. Nutritional modulation is an efficient way in eggshell quality improvement, and modulating calcium size, the ratio of calcium and phosphorus, and supplementing with vitamin in diets have been widely used in duck industry. Zinc (Zn) is one of the microelements in eggshell formation. Dietary Zn supplementation can improve shell quality and structure, but its mechanism is not clear. The current project will thus focus on the formation of mammillary knobs and palisade crystals, investigate the changes of shell quality, matrix proteins, and shell structure with Zn supplementation by using the quasi-static compression texture, western blotting/ immuno-gold localization, and scanning electron microscope/X-ray diffraction methods, respectively. The major associated proteins will be identified by using isotope tags for relative and absolute quantitation (iTRAQ) and mass-spectrometry, and clarify the key proteins and mechanism involved in shell structure affected by Zn. Then the key proteins and mechanism will be proved by the test in vitro with and without adding inhibitors of key proteins. The current project will disclose the functional mechanism of Zn regulating matrix proteins in the formation phase of eggshell structure , and provide scientific evidence for eggshell quality improvement for laying ducks.

蛋壳品质是鸭蛋重要的经济和外观性状，蛋壳品质的降低严重制约蛋鸭养殖业和鸭蛋加工业的优质高效发展。营养是调控蛋壳品质的重要途径，如调节饲粮钙源、钙磷比例、补充维生素等研究成果已应用于生产实践。锌是蛋壳形成的必需微量元素，可改善蛋壳品质和结构，但调控机制不清楚。本项目以蛋壳关键结构-乳突和栅栏层的形成过程为研究主线，采用食品物性结构分析仪、免疫印迹/免疫胶体金技术、扫描电镜/X-单晶衍射技术研究锌对蛋壳品质、基质蛋白和蛋壳结构的影响；通过同位素标记相对和绝对定量技术（iTRAQ）和生物信息学手段，研究锌对子宫液中基质蛋白表达的影响，解析锌调控蛋壳结构的关键基质蛋白和作用途径；在体外特定反应器模拟蛋壳形成，采集子宫液，通过添加蛋白抑制剂的对比试验，进一步确认基质蛋白在锌调控蛋壳结构的作用机制。研究成果可揭示锌通过基质蛋白调控蛋壳结构和品质的作用机制，为运用微量元素锌改善蛋壳品质提供科学依据。

蛋壳品质是鸭蛋重要的经济和外观性状，蛋壳品质的降低严重制约蛋鸭养殖业和鸭蛋加工业的优质高效发展。锌是蛋壳形成的必需微量元素，可改善蛋壳品质和结构，但调控机制不清楚。本项目研究了锌对蛋壳品质、超微结构和蛋壳组分的影响，在乳突和栅栏层的形成期，探讨锌对钙离子代谢和基质蛋白表达的影响，并进行验证。结果表明，1）饲粮添加锌（0~160 mg/kg）可提高蛋壳的强度和韧性，改善蛋壳结构，并随添加水平增加，呈二次曲线变化。拟合曲线得产蛋后期蛋鸭饲粮锌得适宜添加水平为基础饲粮（锌，34.0 mg/kg）添加~85 mg/kg。2）锌主要是通过影响蛋壳乳突结构形成，增加乳突致密性，减少变异乳突结构的发生。3）锌对蛋壳结构改善作用一方面通过影响骨钙动员，调控蛋壳腺内HCO3-转运载体表达而影响钙代谢，一方面调控基质蛋白尤其是具有免疫防御功能的基质蛋白表达，从而改善蛋壳结构和品质。研究成果可揭示锌调控蛋壳结构和品质的作用机制，为运用微量元素锌改善蛋壳品质提供科学依据。