褐飞虱体内类酵母共生菌与氨基酸营养的关系

利用全纯人工饲料饲喂技术，研究了缺失不同氨基酸对高温(35℃)处理后的缺菌褐飞虱Nilaparvata lugens Stål相对生长速度、体内共生菌数量的影响，发现10种必需氨基酸对缺菌褐飞虱生长的影响明显大于10种非必需氨基酸，饲料中必需氨基酸的缺少对褐飞虱（特别是高温处理褐飞虱）体内共生菌数量有一定的刺激作用。分析了缺菌试虫体内氨基酸组成和转氨酶活性的变化规律，发现在摄取的氨基酸营养相同的条件下（用全纯饲料D-97饲养），高温处理试虫体内蛋白质氨基酸组成无明显变化，而游离氨基酸总量明显上升，且必需氨基酸所占比例显著下降，其中组氨酸（His）、异亮氨酸（Ile）、亮氨酸（Leu）、赖氨酸（Lys）、蛋氨酸（Met）和苯丙氨酸（Phe）摩尔百分含量均显著下降，表明必需氨基酸的相对缺乏可能是体内蛋白质合成受阻的一个重要原因，推测这可能是由于试虫体内共生菌数减少致使所合成的必需氨基酸减少而引起。处理试虫体内谷氨酰胺合成酶（GS）和丙氨酸氨基转移酶（ALT）活性明显提高，天冬氨酸氨基转移酶(AST)活性显著降低，结合游离氨基酸中谷氨酰胺（Gln）显著增多，推测类酵母共生菌可能利用谷氨酰胺等为原料进行必需氨基酸的合成。

Relationship between yeast-like symbiotes and amino acid requirements in the rice brown planthopper, Nilaparvata lugens St(a)l (Homoptera: Delphacidae)

The aposymbiotic  Nilaparvata lugens Stål was obtained by three day high temperature treatment (35℃) and then reared on chemically defined diets with one of 20 amino acids deleted. The relative growth rate and number of yeast like symbiotes of aposymbiotic  N. lugens were studied. The results showed that tenessential amino acids were more important for the growth of aposymbiotic N. lugens than ten non essential ones, and the number of yeast like symbiotes increased in N. lugens, especially in aposymbiotic ones, which were reared on diets with one of essential amino acids deleted. The amino acid composition and activity of transamidase in aposymbiotic N. lugens reared on the complete diet D-97 were also tested. There was no change in protein composition in aposymbiotic N. lugens, but the total amount of free amino acids increased significantly and the ratio of essential amino acids decreased, with the molar percentage of essential amino acids such as histidine, isoleucine, leucine, lysine, methionine and phenylalanine decreased markedly. The results suggested a relative reduction of the essential amino acids be an important factor on  hindering protein synthesis. The activity of glutamine synthetase (GS) and alanine aminotransferase (ALT) increased obviously, while aspartate aminotransferase (AST) decreased distinctly. Combined with the result that glutamine increased remarkably, it was inferred that yeast like symbiotes may use glutamine as resource to synthesize essential amino acids.   