Effective disposal of nitrogen waste in blood‐fed Aedes aegypti mosquitoes requires alanine aminotransferase

ABSTRACT To better understand the mechanisms responsible for the success of female mosquitoes in their disposal of excess nitrogen, we investigated the role of alanine aminotransferase (ALAT) in blood‐fed Aedes aegypti. Transcript and protein levels from the 2 ALAT genes were analyzed in sucrose‐ an...

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Bibliographic Details
Published in:The FASEB journal 2016-01, Vol.30 (1), p.111-120
Main Authors: Mazzalupo, Stacy, Isoe, Jun, Belloni, Virginia, Scaraffia, Patricia Y.
Format: Article
Language:English
Subjects:
Aedes - enzymology
Aedes - genetics
Aedes aegypti
Alanine Transaminase - metabolism
ammonia
Animals
Digestion - physiology
Fat Body - metabolism
Female
gene silencing
Nitrogen - metabolism
protein expression
Research Communication
RNA interference
RNA, Double-Stranded - metabolism
uric acid
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Summary:ABSTRACT To better understand the mechanisms responsible for the success of female mosquitoes in their disposal of excess nitrogen, we investigated the role of alanine aminotransferase (ALAT) in blood‐fed Aedes aegypti. Transcript and protein levels from the 2 ALAT genes were analyzed in sucrose‐ and blood‐fed A. aegypti tissues. ALAT1 and ALAT2 exhibit distinct expression patterns in tissues during the first gonotrophic cycle. Injection of female mosquitoes with either double‐stranded RNA (dsRNA)‐ALAT1 or dsRNA ALAT2 significantly decreased mRNA and protein levels of ALAT1 or ALAT2 in fat body, thorax, and Malpighian tubules compared with dsRNA firefly luciferase‐injected control mosquitoes. The silencing of either A. aegypti ALAT1 or ALAT2 caused unexpected phenotypes such as a delay in blood digestion, a massive accumulation of uric acid in the midgut posterior region, and a significant decrease of nitrogen waste excretion during the first 48 h after blood feeding. Concurrently, the expression of genes encoding xanthine dehydrogenase and ammonia transporter (Rhesus 50 glycoprotein) were significantly increased in tissues of both ALAT1‐ and ALAT2‐deficient females. Moreover, perturbation of ALAT1 and ALAT2 in the female mosquitoes delayed oviposition and reduced egg production. These novel findings underscore the efficient mechanisms that blood‐fed mosquitoes use to avoid ammonia toxicity and free radical damage.—Mazzalupo, S., Isoe, J., Belloni, V., Scaraffia, P. Y. Effective disposal of nitrogen waste in blood‐fed Aedes aegypti mosquitoes requires alanine aminotransferase. FASEB J. 30, 111‐120 (2016). www.fasebj.org
ISSN:0892-6638
1530-6860
DOI:10.1096/fj.15-277087