Factors affecting ascorbic acid biosynthesis in chickens. I. Adaptation of an assay and the effect of age, sex and food deprivation
Factors affecting ascorbic acid biosynthesis in chickens. I. Adaptation of an assay and the effect of age, sex and food deprivation
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DOI：
10.1046/j.1439-0396.2000.00286.x
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发表时间：
2000-09-01
影响因子：
2.7
通讯作者：
Toler, JE
中科院分区：
文献类型：
--
作者：
Hooper, CL;Maurice, DV;Toler, JE
本研究的目的是采用一种测定方法来测量鸡的 L-古洛糖酸内酯氧化酶 (GLO) 活性，这是抗坏血酸合成的最后一步，并使用该程序来研究性别、年龄和食物匮乏的影响。为了适应用于哺乳动物组织的程序，使用鸡肾估计动力学常数，并在组织储存和分布均匀性方面优化测定条件。以个体动物为实验单位，采用标准化测定法进行了一系列实验。仅在成熟鸟类中检测到性别差异，其中雄性鸡的 GLO 活性低于雌性。未成熟雏鸡 GLO 活动的时间过程变化最好通过由抛物线与直线连接组成的分段响应函数来表征。估计最大值出现在第 13 天，从第 16 天开始线性下降。函数关系没有提供早期滞后期或未成熟鸡 4 周时达到峰值的证据。配对鸟类组中的食物匮乏证明了食物对鸡 GLO 活性的影响。禁食禁水12小时和禁食24小时对GLO活性没有显着影响。 48 小时的食物剥夺导致 GLO 活性显着下降，并且 72 小时的食物剥夺并没有进一步抑制 GLO 活性。初始 GLO 活性在补充后 24 小时内恢复。结果清楚地表明，性别、年龄和饥饿是鸡抗坏血酸合成的决定因素。
The objective of this study was to adapt an assay to measure L-gulonolactone oxidase (GLO) activity, the final step in ascorbate synthesis, in chickens and use the procedure to study the effect of gender, age, and food deprivation. To adapt a procedure used for mammalian tissues the kinetic constants were estimated using chicken kidney and assay conditions optimized in terms of storage of tissue and homogeneity of distribution. A series of experiments were conducted using the standardized assay with individual animals as the experimental unit. Gender differences were detected only in mature birds with male chickens having lower GLO activity than females. Time-course changes in GLO activity in immature chicks were best characterized by a segmented response function consisting of a parabola joined to a straight line. The maximum value was estimated to occur at 13 days and from day 16 declined linearly. The functional relationship did not provide evidence of an early lag period or a peak at 4 weeks in immature chickens. Food deprivation in matched groups of birds demonstrated the effect of food on GLO activity in chickens. Food and water deprivation for 12 h and food deprivation for 24 h had no significant effect on GLO activity. Food deprivation for 48 h caused a significant decrease in GLO activity and it was not further depressed by deprivation for 72 h. Initial GLO activity was restored within 24 h of repletion. The results clearly demonstrated that gender, age, and starvation are determinants of ascorbate synthesis in chickens.