Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta.
Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta.
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DOI：
10.1371/journal.pone.0045455
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Nijhout HF
中科院分区：
文献类型：
--
作者：
Callier V;Nijhout HF
通过个体发育的代谢率的低异速生长标度的解释通常分为两类：对氧气输送的供应侧限制，或对氧气的质量特异性内在需求降低。在许多动物中，随着身体的成长，供给和需求同时增加，因此不可能梳理出变化的供给和需求对观察到的代谢率缩放的相对贡献。在昆虫幼虫中，气管系统的大型组成部分在每次蜕皮时都会固定尺寸，但随后在下一次蜕皮之前保持不变。天蛾幼虫在蜕皮之间的质量增加了10倍，导致氧气需求增加，而供应量却没有随之增加。在蜕皮时，气管系统脱落并被一个新的更大的系统所取代。由于气管系统的这种不连续的生长，昆虫幼虫提出了一个理想的系统，在其中检查的相对贡献的供应和需求的氧气的个体发育的代谢率的缩放。我们观察到，代谢率在开始连续龄期规模hypoallometrically。这种特定内在需求的减少可能是由于高代谢活性组织（中肠）的比例降低或单个细胞中线粒体活性降低。我们发现，内在需求减少，介导的比例减少，高代谢活性组织在第五龄，沿着减少，在特定的线粒体活性，有助于代谢率的低异速生长缩放。
Explanations for the hypoallometric scaling of metabolic rate through ontogeny generally fall into two categories: supply-side constraints on delivery of oxygen, or decreased mass-specific intrinsic demand for oxygen. In many animals, supply and demand increase together as the body grows, thus making it impossible to tease apart the relative contributions of changing supply and demand to the observed scaling of metabolic rate. In larval insects, the large components of the tracheal system are set in size at each molt, but then remain constant in size until the next molt. Larvae of Manduca sexta increase up to ten-fold in mass between molts, leading to increased oxygen need without a concomitant increase in supply. At the molt, the tracheal system is shed and replaced with a new, larger one. Due to this discontinuous growth of the tracheal system, insect larvae present an ideal system in which to examine the relative contributions of supply and demand of oxygen to the ontogenetic scaling of metabolic rate. We observed that the metabolic rate at the beginning of successive instars scales hypoallometrically. This decrease in specific intrinsic demand could be due to a decrease in the proportion of highly metabolically active tissues (the midgut) or to a decrease in mitochondrial activity in individual cells. We found that decreased intrinsic demand, mediated by a decrease in the proportion of highly metabolically active tissues in the fifth instar, along with a decrease in the specific mitochondrial activity, contribute to the hypoallometric scaling of metabolic rate.
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DOI：
10.1073/pnas.2334605100
发表时间：
2003-11-25
影响因子：
11.1
作者：
Kozlowski, J;Konarzewski, M;Gawelczyk, AT
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影响因子：
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DOI：
10.1073/pnas.1106556108
发表时间：
2011-08-30
影响因子：
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作者：
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