University of Regensburg, Institute of Zoology, Universitätsstraße 31, 93053, Regensburg, Germany.
University of Regensburg, Institute of Zoology, Universitätsstraße 31, 93053, Regensburg, Germany.
Insect Biochem Mol Biol. 2024 Oct;173:104179. doi: 10.1016/j.ibmb.2024.104179. Epub 2024 Aug 28.
Sugar consumption increases the fecundity and longevity in many species of parasitic wasps (parasitoids) but whether these insects use sugars to synthesize significant amounts of fatty acids and storage fat de novo (lipogenesis) is discussed controversially. It has long been assumed that parasitic wasps lost this ability during evolution, mainly because in several species wasps with ad libitum access to sugar did not increase teneral lipid levels. Recent studies demonstrated that many species are nonetheless capable of synthesizing fatty acids de novo from glucose. It is unclear, however, whether also other sugars are used for fatty acid biosynthesis and whether an increase of sugar concentration to levels occurring in natural sugar sources translates into higher fatty acid production. Furthermore, it has been suggested that fatty acid production in parasitoids is negligible compared to species increasing teneral fat reserves such as Drosophila melanogaster. Here we show by stable isotope labeling experiments that females of Nasonia vitripennis convert D-glucose, D-fructose, sucrose, and α,α-trehalose, major sugars consumed by adult parasitoids in nature, equally well to palmitic, stearic, oleic, and linoleic acid. Lipogenesis from D-galactose occurs as well albeit to a lesser extent. Sugar concentration is crucial for lipogenic activity, and almost 80% of de novo synthesized fatty acids were incorporated into storage fat (triacylglycerides). Comparison of fatty acid biosynthesis within a 48-h feeding period with D. melanogaster revealed that N. vitripennis produced approximately half as many fatty acids per body mass unit. Both species fed equal amounts of the glucose offered. We conclude that lipogenesis is far from negligible in N. vitripennis and plays an important role for the energy balance when teneral lipid reserves deplete.
糖的消耗会增加许多寄生蜂（寄生蜂）物种的繁殖力和寿命，但这些昆虫是否利用糖来合成大量脂肪酸和新的储存脂肪（脂肪生成），这一点存在争议。长期以来，人们一直认为寄生蜂在进化过程中失去了这种能力，主要是因为在一些物种中，蜂类可以自由获取糖，但它们的初生脂肪水平并没有增加。最近的研究表明，许多物种仍然能够从葡萄糖中合成脂肪酸。然而，目前尚不清楚其他糖是否也被用于脂肪酸生物合成，以及糖浓度的增加是否会转化为更高的脂肪酸产量。此外，有人认为，与像黑腹果蝇这样增加初生脂肪储备的物种相比，寄生蜂的脂肪酸生成可以忽略不计。在这里，我们通过稳定同位素标记实验表明，丽蝇蛹集金小蜂的雌蜂能够很好地将 D-葡萄糖、D-果糖、蔗糖和α，α-海藻糖转化为棕榈酸、硬脂酸、油酸和亚油酸，这些都是在自然界中成年寄生蜂消耗的主要糖。尽管程度较小，但 D-半乳糖也可以进行脂肪生成。糖浓度对脂肪生成活性至关重要，几乎 80%的新合成脂肪酸被纳入储存脂肪（三酰基甘油）。将 48 小时喂养期内的脂肪酸生物合成与黑腹果蝇进行比较后发现，丽蝇蛹集金小蜂每单位体质量产生的脂肪酸约为黑腹果蝇的一半。两种物种都消耗了提供的葡萄糖的相同量。我们得出结论，脂肪生成在丽蝇蛹集金小蜂中远非微不足道，当初生脂肪储备耗尽时，它对能量平衡起着重要作用。
