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首页> 外文期刊>The Journal of Experimental Biology >Fate of dietary sucrose and neosynthesis of amino acids in the pea aphid, Acyrthosiphon pisum, reared on different diets
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Fate of dietary sucrose and neosynthesis of amino acids in the pea aphid, Acyrthosiphon pisum, reared on different diets

机译：不同饮食饲养豌豆蚜虫的饮食蔗糖的命运和氨基酸的新合成

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摘要

The fate of sucrose, the major nutrient of an aphid's natural food, was explored by radiolabeling in the pea aphid Acyrthosiphon pisum. To investigate the influence of nitrogen quality of food on amino acid neosynthesis, pea aphids were reared on two artificial diets differing in their amino acid composition. The first (diet A) had an equilibrated amino acid balance, similar to that derived from analysis of aphid carcass, and the other (diet B) had an unbalanced amino acid composition similar to that of legume phloem sap. Aphids grown on either diet expired the same quantity of sucrose carbon as CO sub(2), amounting to 25-30% of the ingested sucrose catabolized in oxidation pathways. On diet A, the aphids excreted through honeydew about twice as much sucrose carbon as on diet B (amounting to 12.6% of the ingested sucrose for diet A and 8.4% for diet B), while amounts of sucrose carbons incorporated into exuviae were almost identical (1.9% of the ingested sucrose on diet A and 2.7% on diet B). There was also no difference in the amounts of sucrose carbon incorporated into the aphid tissues, which represented close to 50% of the ingested sucrose. Sucrose carbons in the aphid tissues were mainly incorporated into lipids and the quantities involved were the same in aphids reared on either diet. On diet B, we observed neosynthesis of all protein amino acids from sucrose carbons and, for the first time in an aphid, we directly demonstrated the synthesis of the essential amino acids leucine, valine and phenylalanine. Amino acid neosynthesis from sucrose was significantly higher on diet B (11.5% of ingested sucrose carbons) than on diet A (5.4%). On diet A, neosynthesis of most of the amino acids was significantly diminished, and synthesis of two of them (histidine and arginine) was completely suppressed. The origin of amino acids egested through honeydew was determined from the specific activity of the free amino acid pool in the aphid. Aphids are able to adjust to variation in dietary amino acids by independent egestion of each amino acid. While more than 80% of excreted nitrogen was from food amino acids, different amino acids were excreted in honeydew of aphids reared on the two diets. The conversion yields of dietary sucrose into aphid amino acids determined in this study were combined with those obtained previously by studying the fate of amino acids in pea aphids reared on diet A. The origin of all the amino acid carbons in aphid tissues was thus computed, and the metabolic abilities of aphid are discussed from an adaptive point of view, with respect to their symbiotic status.
机译：蔗糖是蚜虫天然食物的主要营养物质，其命运是通过在豌豆蚜虫Acyrthosiphon pisum中进行放射性标记研究的。为了研究食物氮素对氨基酸新合成的影响，将豌豆蚜虫饲养在两种氨基酸组成不同的人工饲料上。第一个（饮食A）具有平衡的氨基酸平衡，类似于从蚜虫car体分析得出的氨基酸平衡，另一个（饮食B）具有类似于豆类韧皮部汁液的不平衡氨基酸组成。两种饮食中生长的蚜虫的蔗糖碳含量都与CO sub（2）相同，相当于在氧化途径中分解代谢的摄入蔗糖的25-30％。在饮食A上，蚜虫通过蜜露排出的蔗糖碳约为饮食B的两倍（占饮食A摄入的蔗糖的12.6％，占饮食B摄入的蔗糖的8.4％），而掺入到Exuviae中的蔗糖碳的量几乎相同（饮食A摄入的蔗糖为1.9％，饮食B为2.7％）。掺入蚜虫组织中的蔗糖碳量也没有差异，其占摄入的蔗糖的近50％。蚜虫组织中的蔗糖碳主要掺入脂质中，两种饮食饲养的蚜虫中所含碳量相同。在饮食B中，我们观察到了蔗糖碳中所有蛋白质氨基酸的新合成，并且首次在蚜虫中，我们直接证明了必需氨基酸亮氨酸，缬氨酸和苯丙氨酸的合成。饮食B（摄入的蔗糖碳的11.5％）比蔗糖A（5.4％）的蔗糖氨基酸新合成显着更高。在饮食A中，大多数氨基酸的新合成显着减少，其中两个氨基酸（组氨酸和精氨酸）的合成被完全抑制。由蜜露所产的氨基酸的来源是由蚜虫中游离氨基酸库的比活确定的。蚜虫能够通过独立摄取每个氨基酸来适应饮食氨基酸的变化。虽然超过80％的排泄氮是从食物氨基酸中分泌出来的，但两种饮食饲养的蚜虫蜜露却排泄了不同的氨基酸。通过这项研究确定的日粮中蔗糖向蚜虫氨基酸的转化率与先前通过研究以饮食A饲养的豌豆蚜虫的氨基酸命运所获得的转化率相结合。从而计算了蚜虫组织中所有氨基酸碳的来源，并从适应性角度探讨了蚜虫的代谢能力及其共生状态。

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