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Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta.

Publication ,  Journal Article
Callier, V; Nijhout, HF
Published in: PloS one
January 2012

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.

Duke Scholars

Published In

PloS one

DOI

EISSN

1932-6203

ISSN

1932-6203

Publication Date

January 2012

Volume

7

Issue

9

Start / End Page

e45455

Related Subject Headings

  • Oxygen Consumption
  • Molting
  • Mitochondria
  • Manduca
  • General Science & Technology
  • Energy Metabolism
  • Electron Transport Complex IV
  • Body Size
  • Animals
 

Citation

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MLA
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Callier, V., & Nijhout, H. F. (2012). Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta. PloS One, 7(9), e45455. https://doi.org/10.1371/journal.pone.0045455
Callier, Viviane, and H Frederik Nijhout. “Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta.PloS One 7, no. 9 (January 2012): e45455. https://doi.org/10.1371/journal.pone.0045455.
Callier, Viviane, and H. Frederik Nijhout. “Supply-side constraints are insufficient to explain the ontogenetic scaling of metabolic rate in the tobacco Hornworm, Manduca sexta.PloS One, vol. 7, no. 9, Jan. 2012, p. e45455. Epmc, doi:10.1371/journal.pone.0045455.

Published In

PloS one

DOI

EISSN

1932-6203

ISSN

1932-6203

Publication Date

January 2012

Volume

7

Issue

9

Start / End Page

e45455

Related Subject Headings

  • Oxygen Consumption
  • Molting
  • Mitochondria
  • Manduca
  • General Science & Technology
  • Energy Metabolism
  • Electron Transport Complex IV
  • Body Size
  • Animals