Kushwaha R P, Jensen L S
J Nutr. 1975 Feb;105(2):226-32. doi: 10.1093/jn/105.2.226.
Studies were conducted to determine the effect of choline deficiency on utilization of various labeled precursors of choline and rate of choline biosynthesis in mature Japanese quail. A deficiency of dietary choline did not change the in vivo incorporation of 14C-label from (1,2-14C) ETHANOLAMINE, N, N-dimethyl (1,2-14C) ethanolamine, and L-(methyl-14C) methionine into liver phosphatidylcholine (PC) or total phospholipids. Incorporation of radioactivity from (14C) serine into liver PC was increased, but the difference was not significant (PGREATER THAN3.35). In vitro studies confirmed these observations as there were no differences in liver microsomal methyltransferase activities, expressed as the incorporation of methyl-14C from labeled S-adenosylmethionine into microsomal PC from quail fed a purified diet with with or without choline. Rats appeared to incorporate an increased amount of 14C into PC when fed a diet devoid of choline, but the differences were not significant. There were differences in methyltransferase activities among species, and quail had the lowest activity. A slower turnover of choline was found in quail liver (t1/2=7.5 hours) as compared with that of hen liver (t1/2=2.0 hours). The methyltransferase responsible for the first methylation of phosphatidyl-ethanolamine from quail liver appears to differ from most other biosynthetic enzymes in that it occurs in liver and catalyzes the reaction at a slow rate but cannot adapt to exogenous choline supply to meet the requirements for normal bodily functions in quail.
开展了多项研究，以确定胆碱缺乏对成熟日本鹌鹑体内各种标记胆碱前体的利用及胆碱生物合成速率的影响。日粮胆碱缺乏并未改变(1,2-¹⁴C)乙醇胺、N,N-二甲基(1,2-¹⁴C)乙醇胺和L-(甲基-¹⁴C)甲硫氨酸中¹⁴C标记物在体内掺入肝脏磷脂酰胆碱(PC)或总磷脂中的情况。(¹⁴C)丝氨酸的放射性掺入肝脏PC的量有所增加，但差异不显著(P＞3.35)。体外研究证实了这些观察结果，因为以从标记的S-腺苷甲硫氨酸掺入微粒体PC中的甲基-¹⁴C来表示的肝脏微粒体甲基转移酶活性，在饲喂含或不含胆碱的纯化日粮的鹌鹑中没有差异。当饲喂不含胆碱的日粮时，大鼠似乎向PC中掺入了更多的¹⁴C，但差异不显著。不同物种间甲基转移酶活性存在差异，鹌鹑的活性最低。与母鸡肝脏(t1/2 = 2.0小时)相比，鹌鹑肝脏中胆碱的周转较慢(t1/2 = 7.5小时)。鹌鹑肝脏中负责磷脂酰乙醇胺首次甲基化的甲基转移酶似乎与大多数其他生物合成酶不同，因为它存在于肝脏中，催化反应的速率较慢，但无法适应外源性胆碱供应以满足鹌鹑正常身体功能的需求。
