家蚕体内因缺乏维生素B_6而引起的若干代谢变动

Effects of vitamin B_6 deficiency on the amino acid metabolism, fatty acid metabolism and aminotransferase activity of the silkworm, Bombyx mori

采用不含桑叶粉末、以去维生素牛乳酪蛋白为蛋白源的准合成饲料饲育家蚕Bombyxmori 5龄幼虫 ,探讨了缺乏维生素B6 (VB6 )对蚕体氨基酸代谢、脂肪酸代谢以及转氨酶活力的影响。缺乏VB6 引起支链氨基酸分解代谢受阻 ,幼虫体液中大量积累亮氨酸、缬氨酸和异亮氨酸。同时因绢丝腺发育停滞 ,丝氨酸也在体液中积累。另一方面 ,缺乏VB6 幼虫体液中赖氨酸、脯氨酸、精氨酸、甲硫氨酸和谷氨酸含量减少 ,其中赖氨酸尤为突出。推测缺乏VB6 引起赖氨酸分解代谢亢进。结果还表明 ,缺乏VB6 幼虫体内脂肪酸代谢异常 。

The effects of vitamin B 6 (VB 6) deficiency on the amino acid metabolism, fatty acid metabolism and aminotransferase activity of the silkworm, Bombyx mori , were studied in newly ecdysed 5th instar larvae reared on a semisynthetic diet that contained no mulberry powder and in which vitamin free casein was the protein source. Under VB 6 deficient conditions, larval growth was retarded, the catabolism of branched chain amino acid (leucine, valine, isoleucine) was inhibited, and lysine catabolism was stimulated. The leucine, valine, isoleucine and serine content in haemolymph were markedly increased by VB 6 deficiency. Conversely, lysine, proline, arginine, methionine and glutamine content decreased, especially markedly in lysine. The lack of dietary VB 6 also inhibited synthetic metabolism of fatty acids and reduced the activity of glutamic pyruvic transaminase.