Research of nitrogen metabolism controlling system in insects

鳞翅目毛虫体内的脂肪酸氨基酸结合物(FAC)可促进其氮素同化，促进其生长发育。本研究以鳞翅目毛虫为研究对象，首次将其与斜纹夜蛾、家蚕、烟草角虫等几种昆虫的中肠组织孵育，在体外观察到谷氨酸结合物的生物合成。这意味着在鳞翅目毛虫中，谷氨酸直接与脂肪酸结合，这表明合成路线与果蝇的情况相同，但与蟋蟀的情况明显不同。蟋蟀首先将谷氨酰胺与脂肪酸偶联，然后修饰谷氨酰胺部分的侧链，形成谷氨酸偶联物。虽然这些昆虫的FAC有一个共同点，如定位于中肠组织，以及相同的由谷氨酰胺/谷氨酸组成的类似模式，但这一发现表明，至少谷氨酸型FAC在这些昆虫中是独立发展的。

Fatty acid amino acid conjugates (FACs) in lepidopteran caterpillars enhance their nitrogen assimilation and are considered to accelerate their growth ratio. The research focused on the biosynthetic mechanism of FACs in lepidopteran caterpillars.For the first time, in vitro biosynthesis of glutamate conjugates were observed when the substrates were incubated with a midgut tissue of Spodoptera litura, silkworm, tobacco hornworm and a few other species. That means glutamate is directly conjugated with fatty acid in lepidopteran caterpillars, suggesting the synthetic routeis the same with the case of fruit fly Drosophila melanogaster but clearly different from the case of crickets Gryllus emma. Crickets first conjugate glutamine with fatty acid and modify the side chain of glutamine moiety to make a glutamate conjugate. Although FACs in these insects share a common ground such as localization in themidgut tissues and the same analog pattern consisting of glutamine/glutamate, the finding suggest that at least glutamate type FACs were independently developed in these insect order.