0
0
The eggs of the mosquito responsible for transmitting the dengue and Chikungunya viruses have demonstrated an ability to withstand extreme dehydration by modifying their metabolic processes, a study has revealed. This discovery holds the potential for developing novel strategies to curb the spread of these diseases.
Scientists from the Institute for Stem Cell Science and Regenerative Medicine in Bengaluru and the Indian Institute of Technology, Mandi observed that cells primarily consist of water, making desiccation a potentially lethal event for any organism, as the structures of many proteins and cellular molecules rely on sufficient hydration.
While numerous types of microorganisms have evolved mechanisms to survive desiccation, only a select few animals possess this adaptation. Among them is the Aedes aegypti mosquito, a carrier of various viral diseases, including Zika, dengue, yellow fever, and Chikungunya.
Originally native to North Africa, Aedes aegypti has spread globally and now poses a threat in warm, humid regions around the world. Aedes eggs take between 48 to 72 hours to develop into larvae, and the researchers discovered that they must be at least 15 hours old to endure desiccation. Eggs that experienced dehydration before reaching this stage failed to hatch upon rehydration.
“Given the significance of Aedes aegypti as a primary vector for numerous viral diseases affecting nearly half of the world’s population, and considering the rapid geographical expansion of this mosquito vector, these findings offer a basis for diminishing Aedes egg survival and global dissemination,” stated Sunil Laxman from the Institute for Stem Cell Science and Regenerative Medicine. He also noted, “Aedes aegypti eggs, along with potential innovations affecting other aspects of egg desiccation tolerance, may prove valuable as vector-control agents.”
The team compared the proteomes of viable eggs that had been subjected to desiccation with those that had not. They identified significant alterations in metabolic pathways within the desiccated eggs. These changes included heightened levels of enzymes that facilitate fat metabolism, as well as a reduction in enzymes that collectively steer cellular metabolism towards the generation and utilization of fatty acids. Overall, metabolic activity decreased, while the levels of the amino acids arginine and glutamine increased. Additionally, enzymes that mitigate the detrimental effects of oxidative stress, a known consequence of dehydration, were also elevated.
Arginine molecules combine to form polyamines, which are recognized for safeguarding nucleic acids, proteins, and membranes from harm. The researchers demonstrated that the eggs accumulate polyamines, suggesting their crucial role in desiccation tolerance. To validate this, they administered an inhibitor of polyamine synthesis to egg-laying female mosquitoes. The resulting eggs exhibited a significantly reduced ability to withstand desiccation compared to those from untreated females. A second inhibitor, targeting fatty acid metabolism, also diminished egg viability post-desiccation. Finally, the researchers established that this fatty acid inhibitor curtailed polyamine synthesis, indicating that one function of heightened fatty acid breakdown is to furnish the energy necessary for the production of protective polyamines.
“Aedes mosquito eggs have the capacity to endure complete desiccation indefinitely and can hatch into viable larvae. The embryos reconfigure their metabolism when subjected to drying, thereby safeguarding themselves through desiccation, and they reanimate once water becomes accessible again,” added Laxman.
