How do consumers deal with stoichiometric constraints? Lessons from functional genomics using Daphnia pulex
How do consumers deal with stoichiometric constraints? Lessons from functional genomics using Daphnia pulex
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DOI：
10.1111/j.1365-294x.2011.05102.x
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发表时间：
2011-06-01
影响因子：
4.9
通讯作者：
Colbourne, John K.
中科院分区：
文献类型：
--
作者：
Jeyasingh, Punidan D.;Ragavendran, Ashok;Colbourne, John K.
在大多数生态系统中，能量(碳、碳)和某些物质元素(如磷、磷)的供需不一致在大多数生态系统中普遍存在，并影响营养相互作用的强度和生态系统功能，如生产力和养分循环。然而，我们对在较低级别的生物组织中运行的驱动这种较高级别的生态过程的机制知之甚少。这些信息应该有助于完善在多个组织层面上整合生物过程的理论。了解基因的表达和功能是这个项目的第一步，这些基因在很大程度上是生物体对营养界面化学计量失衡进行生理调节的基础。在这里，我们研究了与其他饲料成分相关的磷的供需变化对Keystone湖栖食草动物Daphnia Pulex基因表达的调节。以LoC-HIP(摩尔C：P类似于100)或HIC-LOP(摩尔C：P类似于900)的藻类饲料饲养5天，在HIC-LOP条件下显著减少生长。微阵列测量了8217个带注释的蛋白质编码基因在不同饮食条件下的转录调控，发现了1818个差异表达(DE)基因；19%是水蚤谱系特有的基因。我们将DE基因映射到代谢途径的全球图表上，以获得对化学计量失衡反应的系统水平的视角。水蚤的不同调控途径参与了限制元素的隔离，以及初级生产者营养胁迫可能触发的代谢调节产物的处理。营养界面的功能基因组学阐明了生态系统中能量和营养通量的化学计量限制的过程的复杂性。
Disaccord between the supply and demand of energy (carbon, C) and certain material elements (e.g. phosphorus, P) across trophic levels is common in most ecosystems and impacts the strength of trophic interactions and ecosystem functions such as productivity and nutrient recycling. Yet, we know little about mechanisms operating at the lower levels of biological organization that drive such higher-level ecological processes. Such information should help refine theories integrating biological processes at multiple levels of organization. Understanding the expression and functions of genes that underlie (to a large degree) physiological adjustments made by organisms to stoichiometric imbalances at trophic interfaces is a first step in this enterprise. Here, we investigate adjustments in gene expression to varying supply and demand of phosphorus relative to other dietary components in the keystone limnetic herbivore, Daphnia pulex. Daphniids were fed an algal diet of either LoC-HiP (molar C:P similar to 100) or HiC-LoP (molar C:P similar to 900) for 5 days, resulting in significant growth reductions under HiC-LoP conditions. Microarrays measured the transcriptional regulation of 8217 annotated protein-coding genes under contrasting dietary conditions and revealed 1818 differentially expressed (DE) genes; 19% are genes unique to the Daphnia lineage. We mapped DE genes onto a global chart of metabolic pathways to obtain a systems-level perspective on the responses to stoichiometric imbalances. Daphnia differentially regulated pathways were involved in sequestering limiting elements, and in dealing with the products of metabolic adjustments that may be triggered by nutrient stress in primary producers. Functional genomics at trophic interfaces illuminate the complexity of processes underlying stoichiometric constraints on energy and nutrient fluxes in ecosystems.