
Excretory role of the midgut in larvae of the tobacco hornworm, Manduca sexta (L.).
Caterpillars of Manduca sexta use two distinct transport mechanisms for the excretion of dyes. One pump (Type A) has a high affinity for acid (anionic) dyes and occurs in the midgut and medial Malpighian tubules. Acid dyes accumulate rapidly in the lumen of the midgut while the Malpighian tubules appear to play only a minor role in the excretion of these dyes. The other pump (Type B) excretes basic (cationic) dyes and is located primarily in the proximal Malpighian tubules. Evidence is presented that hippuric acid competes with acid dyes for excretion by both midgut and Malpighian tubules. After the final-instar larva purges its gut the ability of the midgut and Malpighian tubules to excrete dyes gradually decreases. Sixty hours after the purge only the Malpighian tubules retain some dye excreting activity.
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Related Subject Headings
- Time Factors
- Physiology
- Malpighian Tubules
- Lepidoptera
- Larva
- Hippurates
- Dinitrophenols
- Cloaca
- Biological Transport
- Animals
Citation

Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Time Factors
- Physiology
- Malpighian Tubules
- Lepidoptera
- Larva
- Hippurates
- Dinitrophenols
- Cloaca
- Biological Transport
- Animals