A midgut digestive phospholipase A2 in larval mosquitoes, Aedes albopictus and Culex quinquefasciatus

Authors: ABDULRAHIM, NOR ALIZA - Universiti Malaysia Sarawak; OTHMAN, MARLINI - Universiti Malaysia Sarawak; SABRI, MUNA - Universiti Malaysia Sarawak; Stanley, David

Submitted to: Enzyme Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2018
Publication Date: 5/16/2018
Citation: Abdulrahim, N., Othman, M., Sabri, M., Stanley, D.W. 2018. A midgut digestive phospholipase A2 in larval mosquitoes, Aedes albopictus and Culex quinquefasciatus. Enzyme Research. https://doi.org/10.1155/2018/9703413.
DOI: https://doi.org/10.1155/2018/9703413

Interpretive Summary: Mosquitoes are among the most dangerous insects on Earth because they are vectors of many lethal human diseases, including malaria. To indicate the severity of malaria, in 2015 there were about 212 million malaria infections and almost a half million deaths. Research into many aspects of global research into mosquito biology is driven by needs to reduce malaria infections and deaths by reducing popuations of mosquitoes that transmit the disease. In this paper we report on a digestive enzyme responsible for digesting essential nutrients required by two mosquito species. These nutrients are required in juvenile stages for development into flight-capable adults. Understanding this digestive enzyme may lead to specific tools to inhibit the digestive process and, in effect, starve juveniles before they become adults. This research will be important to scientists working to reduce mosquito populations and ultimately benefit the many humans now at risk for malaria infection.

Technical Abstract: Phospholipase A2 (PLA2) is a secretory digestive enzyme that hydrolyzes ester bond at sn-2 position of dietary phospholipids, creating free fatty acid and lysophopholipid. The free fatty acids (arachidonic acid) are absorbed into midgut cells. Aedes albopictus and Culex quinquefasciatus digestive PLA2 was characterized using a microplate PLA2 assay. The enzyme showed substantial activities at 6 and 8 µg/µl of protein concentration with optimal 39 activity at 20 and 25 µg/µl of substrate concentration in Aedes albopictus and Culex quinquefasciatus respectively. PLA2 activity from both mosquitoes increased in a linear 41 function up to 1-hour of the reaction time. Both enzymes were sensitive to pH and temperature. PLA2 showed higher enzyme activities in pH 8.0 and 9.0 from Aedes albopictus and Culex quinquefasciatus respectively, at 40ºC of incubation. The PLA2 activity decreased in the presence of 5 mM (Aedes albopictus) and 0.5 mM (Culex quinquefasciat) site specific PLA2 inhibitor, oleyloxyethylphosphorylcholine. Based on the migration pattern of the partially purified PLA2 on SDS-PAGE, the protein mass of PLA2 is approximately 25 kDa for both mosquitoes. The information on PLA2 properties derived from this study may facilitate in devising mosquitoes control strategies especially in the development of inhibitors targeting the enzyme active site.