Walton M J, Coloso R M, Cowey C B, Adron J W, Knox D
Br J Nutr. 1984 Mar;51(2):279-87. doi: 10.1079/bjn19840032.
Groups of rainbow trout (Salmo gairdneri) (mean weight 14 g) were given diets containing 0.8, 1.3, 2, 3, 4 or 6 g tryptophan/kg diet for 12 weeks. By analysis of the growth results, the dietary requirement of tryptophan was found to be 2.5 g/kg diet (equivalent to 50 mg/kg biomass per d). Carbon dioxide expired by trout following intraperitoneal injection of [14COOH]tryptophan contained little radioactivity when dietary tryptophan level was low but, above 2.0 g/kg diet, it increased rapidly with increasing dietary tryptophan level. The break point in the dose-response curve did not, however, coincide with that from the growth results. Changes in concentrations of free tryptophan in blood and liver and activity of hepatic tryptophan pyrrolase (EC 1. 13. 11. 11) in response to changes in dietary tryptophan concentration did not provide reliable indicators for quantifying dietary requirement. Unlike the situation in mammals, blood tryptophan was not protein-bound to any appreciable extent. Tryptophan pyrrolase of trout has properties which suggest it has no apoenzyme form. In fish given adequate levels of tryptophan injected intraperitoneally with a tracer dose of [14COOH]tryptophan, 60% of the dose was incorporated into body protein within 1 d. The turnover of the label in this protein is very slow. Those trout given diets deficient in tryptophan suffered from severe scoliosis and lordosis as well as having increased liver and kidney levels of calcium, magnesium, sodium and potassium.
将虹鳟鱼（鲑鱼）（平均体重14克）分成几组，分别投喂含0.8、1.3、2、3、4或6克色氨酸/千克饲料的日粮，持续12周。通过对生长结果的分析，发现色氨酸的日粮需求量为2.5克/千克饲料（相当于每天50毫克/千克生物量）。当日粮色氨酸水平较低时，腹腔注射[14COOH]色氨酸后虹鳟鱼呼出的二氧化碳中放射性很低，但当日粮色氨酸水平高于2.0克/千克饲料时，随着日粮色氨酸水平的升高，二氧化碳中的放射性迅速增加。然而，剂量反应曲线的转折点与生长结果的转折点并不一致。血液和肝脏中游离色氨酸浓度的变化以及肝脏色氨酸吡咯酶（EC 1. 13. 11. 11）活性对日粮色氨酸浓度变化的响应并不能为定量日粮需求提供可靠指标。与哺乳动物的情况不同，虹鳟鱼血液中的色氨酸没有明显程度的蛋白质结合。虹鳟鱼的色氨酸吡咯酶的特性表明它没有脱辅酶形式。给色氨酸水平充足的鱼腹腔注射示踪剂量的[14COOH]色氨酸后，60%的剂量在1天内被整合到体蛋白中。该蛋白中标记物的周转非常缓慢。那些投喂色氨酸缺乏日粮的虹鳟鱼患有严重的脊柱侧凸和脊柱前凸，同时肝脏和肾脏中的钙、镁、钠和钾水平升高。
