Department of Physical Sciences, Indian Institute of Science Education & Research IISER, Mohali, Punjab, India.
Department of Biological Sciences, Indian Institute of Science Education & Research IISER, Mohali, Punjab, India.
PLoS One. 2017 Nov 17;12(11):e0188089. doi: 10.1371/journal.pone.0188089. eCollection 2017.
We used NMR-based metabolomics to test two hypotheses-(i) there will be evolved differences in the metabolome of selected and control populations even under un-infected conditions and (ii) post infection, the metabolomes of the selected and control populations will respond differently. We selected replicate populations of Drosophila melanogaster for increased survivorship (I) against a gram-negative pathogen. We subjected the selected (I) and their control populations (S) to three different treatments: (1) infected with heat-killed bacteria (i), (2) sham infected (s), and (3) untreated (u). We performed 1D and 2D NMR experiments to identify the metabolic differences. Multivariate analysis of the metabolic profiles of the untreated (Iu and Su) flies yielded higher concentrations of lipids, organic acids, sugars, amino acids, NAD and AMP in the Iu treatment as compared to the Su treatment, showing that even in the absence of infection, the metabolome of the I and S regimes was different. In the S and I regimes, post infection/injury, concentration of metabolites directly or indirectly associated with energy related pathways (lipids, organic acids, sugars) declined while the concentration of metabolites that are probably associated with immune response (amino acids) increased. However, in most cases, the I regime flies had a higher concentration of such metabolites even under un-infected conditions. The change in the metabolite concentration upon infection/injury was not always comparable between I and S regimes (in case of lactate, alanine, leucine, lysine, threonine) indicating that the I and S regimes had evolved to respond differentially to infection and to injury.
我们利用基于 NMR 的代谢组学来检验两个假设-（i）即使在未感染的情况下，选择和对照种群的代谢组也会发生进化差异，以及（ii）感染后，选择和对照种群的代谢组将做出不同的反应。我们选择了经过选择的果蝇种群（I）以提高对革兰氏阴性病原体的存活率。我们将选择的种群（I）及其对照种群（S）分别进行了三种不同的处理：（1）用热杀死的细菌感染（i），（2）假感染（s），和（3）未处理（u）。我们进行了 1D 和 2D NMR 实验以鉴定代谢差异。对未处理（Iu 和 Su）的果蝇代谢图谱的多元分析表明，与 Su 处理相比，Iu 处理中的脂质、有机酸、糖、氨基酸、NAD 和 AMP 的浓度更高，这表明即使在没有感染的情况下，I 和 S 处理的代谢组也不同。在 S 和 I 处理中，感染/损伤后，与能量相关途径（脂质、有机酸、糖）直接或间接相关的代谢物的浓度下降，而可能与免疫反应相关的代谢物（氨基酸）的浓度增加。然而，在大多数情况下，即使在未感染的情况下，I 处理的果蝇也具有更高浓度的此类代谢物。感染/损伤后代谢物浓度的变化在 I 和 S 处理之间并不总是可比（在乳酸、丙氨酸、亮氨酸、赖氨酸、苏氨酸的情况下），这表明 I 和 S 处理已经进化为对感染和损伤做出不同的反应。
