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Phenol oxidases from Rhodnius prolixus: temporal and tissue expression pattern and regulation by ecdysone.
F A Genta1, R S Souza, E S Garcia
1Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil. genta@ioc.fiocruz.br
Journal of Insect Physiology
|April 6, 2010
Summary
This study reveals cyclical patterns in prophenoloxidase (PO) enzymatic activity in Rhodnius prolixus nymphs. These cycles, influenced by ecdysone, suggest distinct gene regulation across tissues during development.
Area of Science:
- Biochemistry
- Insect Physiology
- Molecular Biology
Background:
- Propheloloxidase (PO) enzymatic activity is crucial for insect immunity.
- Rhodnius prolixus, a vector for Chagas disease, exhibits significant PO activity in various tissues during its 5th nymphal instar.
Purpose of the Study:
- To investigate the temporal patterns of PO enzymatic activity in the anterior midgut, fat body, and hemolymph of Rhodnius prolixus 5th instar nymphs.
- To determine the influence of ecdysone on PO activity in different tissues.
Main Methods:
- Measurement of PO enzymatic activity across different tissues (anterior midgut, fat body, hemolymph) at various time points post-blood meal.
- Administration of azadirachtin-containing blood meal and ecdysone to assess their effects on PO activity.
Main Results:
- Distinct temporal patterns of PO activity were observed in the fat body, hemolymph, and anterior midgut.
- PO activity in the anterior midgut and hemolymph showed peaks at specific developmental stages, including just before ecdysis.
- Azadirachtin suppressed PO activity, while ecdysone treatment counteracted this suppression, indicating hormonal regulation.
Conclusions:
- Rhodnius prolixus exhibits natural regulating cycles of basal PO expression and activation during 5th instar development.
- Tissue-specific temporal patterns and differential responses to azadirachtin and ecdysone suggest the involvement of distinct PO genes in different organs.
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