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Insulin-like molecules in the beetle Tenebrio molitor
V M Sevala1, V L Sevala, B G Loughton
1Department of Biology, York University, Ontario, Canada.
Cell and Tissue Research
|July 1, 1993
Summary
Researchers found insulin-like peptides in mealworm beetles (Tenebrio molitor), suggesting these molecules regulate insect development and metamorphosis. Blocking insulin disrupted the insect
Area of Science:
- Insect endocrinology
- Neurobiology
- Developmental biology
Background:
- Insulin and insulin-like growth factors (IGFs) are crucial regulators of metabolism and development in vertebrates.
- The role of insulin-like peptides in invertebrate development, particularly in insects, is less understood.
- Tenebrio molitor (mealworm beetle) is a model organism for studying insect metamorphosis.
Purpose of the Study:
- To investigate the presence and function of insulin-like peptides in the nervous system of Tenebrio molitor.
- To determine the role of these peptides in the regulation of pupal-adult development and ecdysis.
Main Methods:
- Immunocytochemical staining of larval, pupal, and adult Tenebrio molitor nervous systems using anti-insulin serum.
- Analysis of staining intensity changes during pupal development.
- Experimental manipulation: injection of anti-insulin serum at specific developmental stages.
- Immunoblotting of insect hemolymph to identify insulin-like molecules.
Main Results:
- Insulin-like peptides were detected in the protocerebrum, corpora allata, and suboesophageal ganglion of Tenebrio molitor.
- Significant changes in staining intensity were observed in protocerebral cells during pupal development, suggesting peptide release.
- Anti-insulin injections at key developmental time points (day 0 and day 3 of pupal stage) significantly delayed pupal-adult ecdysis.
- A 6.5-kDa insulin-like molecule was identified in the hemolymph of day-3 pupae.
Conclusions:
- Insulin-like peptides are present in the Tenebrio molitor nervous system and hemolymph.
- These peptides play a significant role in regulating the timing of metamorphosis and ecdysis in mealworm beetles.
- The findings suggest that the prothoracicotropic hormone (PTTH) in T. molitor may be an insulin-like molecule, highlighting a conserved role for insulin signaling in development.