Symbiotic bacteria enable insect to use a nutritionally inadequate diet
Symbiotic bacteria enable insect to use a nutritionally inadequate diet
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DOI：
10.1098/rspb.2008.1476
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发表时间：
2009-03-07
影响因子：
4.7
通讯作者：
Douglas, A. E.
中科院分区：
文献类型：
--
作者：
Guenduez, E. Akman;Douglas, A. E.
动物通常需要各种营养素（维生素、必需氨基酸等）的饮食供应。因为它们的生物合成能力有限。蚜虫利用植物韧皮部汁液的能力，具有低必需氨基酸含量，已被归因于它们的共生细菌，Buchnera aphidicola，它可以合成这些营养素，但这还没有得到经验证明。我们在这里证明，从以蚕豆植物为食的豌豆蚜虫Acyrthosiphon pisum的切断针茎中获得的韧皮部汁液通常提供的至少一种必需氨基酸含量不足以支持蚜虫生长。补充分析使用蚜虫饲养的化学定义的饮食与每一个氨基酸单独省略显示的能力的共生细菌B。蚜虫合成必需氨基酸的能力超过了除蛋氨酸以外的所有韧皮部氨基酸的营养缺乏。有人提出，这种不足的蛋氨酸是满足蚜虫使用的非蛋白质氨基酸5-甲基蛋氨酸的韧皮部汁液。本研究首次定量证明了细菌共生可以满足植食性蚜虫的营养需求。它显示了与微生物的共生如何使这类动物摆脱了需要平衡膳食供应氨基酸的限制。
Animals generally require a dietary supply of various nutrients (vitamins, essential amino acids, etc.) because their biosynthetic capabilities are limited. The capacity of aphids to use plant phloem sap, with low essential amino acid content, has been attributed to their symbiotic bacteria, Buchnera aphidicola, which can synthesize these nutrients; but this has not been demonstrated empirically. We demonstrate here that phloem sap obtained from the severed stylets of pea aphids Acyrthosiphon pisum feeding on Vicia faba plants generally provided inadequate amounts of at least one essential amino acid to support aphid growth. Complementary analyses using aphids reared on chemically defined diets with each amino acid individually omitted revealed that the capacity of the symbiotic bacterium B. aphidicola to synthesize essential amino acids exceeded the dietary deficit of all phloem amino acids except methionine. It is proposed that this shortfall of methionine was met by aphid usage of the non-protein amino acid 5-methylmethionine in the phloem sap. This study provides the first quantitative demonstration that bacterial symbiosis can meet the nutritional demand of plant-reared aphids. It shows how symbiosis with micro-organisms has enabled this group of animals to escape from the constraint of requiring a balanced dietary supply of amino acids.