The age of mosquitoes is a crucial determinant of their ability to transmit pathogens and their resistance to
insecticides. We investigated changes to the abundance of
proteins found in heads and thoraces of the
malaria mosquitoes Anopheles gambiae and Anopheles stephensi as they aged.
Protein expression changes were assessed using two-dimensional difference gel electrophoresis and the identity of differentially expressed
proteins was determined by using either matrix-assisted
laser desorption ionization tandem time-of-flight mass spectrometry or capillary high-pressure liquid chromatography coupled with a linear ion-trap (LTQ)-Orbitrap XL hybrid mass spectrometer.
Protein biomarkers were validated by semi quantitative Western blot analysis. Nineteen and nine age dependent
protein spots were identified for A. stephensi and A. gambiae, respectively. Among the
proteins down-regulated with age were homologs of ADF/
Cofilin, cytochome c1, heat shock protein-70 and
eukaryotic translation initiation factor 5A (eIF5a).
Proteins up-regulated with age included probable methylmalonate-semialdehyde
dehydrogenase, voltage-dependent
anion-selective channel and
fructose bisphosphate aldolase. Semi quantitative Western blot analysis confirmed expression patterns observed by 2-D DIGE for eIF5a and ADF/
Cofilin. Further work is recommended to determine whether these
biomarkers are robust to
infection, blood feeding and insecticide resistance. Robust
biomarkers could then be incorporated into rapid diagnostic assays for ecological and epidemiological studies.
BIOLOGICAL SIGNIFICANCE: In this study, we have identified several
proteins with characteristic changes in abundance in both A. gambiae and A. stephensi during their aging process. These changes may highlight underlying mechanisms beneath the relationship between mosquito age and factors affecting Plasmodium transmission and mosquito control. The similarity of changes in
protein abundance between these species and the primary
dengue vector Aedes aegypti, has revealed conserved patterns of aging-specific
protein regulation.