TY - JOUR
T1 - Differential ammonia metabolism in Aedes aegypti fat body and midgut tissues
AU - Scaraffia, Patricia Y.
AU - Zhang, Qingfen
AU - Thorson, Kelsey
AU - Wysocki, Vicki H.
AU - Miesfeld, Roger L.
N1 - Funding Information:
We thank Mary Hernandez for rearing mosquitoes. This work was supported by National Institutes of Health Grants (GM-R01-051387 to V.H.W. and R01AI046541 to R.L.M.).
PY - 2010/9
Y1 - 2010/9
N2 - In order to understand at the tissue level how Aedes aegypti copes with toxic ammonia concentrations that result from the rapid metabolism of blood meal proteins, we investigated the incorporation of 15N from 15NH4Cl into amino acids using an in vitro tissue culture system. Fat body or midgut tissues from female mosquitoes were incubated in an Aedes saline solution supplemented with glucose and 15NH4Cl for 10-40min. The media were then mixed with deuterium-labeled amino acids, dried and derivatized. The 15N-labeled and unlabeled amino acids in each sample were quantified by mass spectrometry techniques. The results demonstrate that both tissues efficiently incorporate ammonia into amino acids, however, the specific metabolic pathways are distinct. In the fat body, the 15N from 15NH4Cl is first incorporated into the amide side chain of Gln and then into the amino group of Gln, Glu, Ala and Pro. This process mainly occurs via the glutamine synthetase (GS) and glutamate synthase (GltS) pathway. In contrast, 15N in midgut is first incorporated into the amino group of Glu and Ala, and then into the amide side chain of Gln. Interestingly, our data show that the GS/GltS pathway is not functional in the midgut. Instead, midgut cells detoxify ammonia by glutamate dehydrogenase, alanine aminotransferase and GS. These data provide new insights into ammonia metabolism in A. aegypti mosquitoes.
AB - In order to understand at the tissue level how Aedes aegypti copes with toxic ammonia concentrations that result from the rapid metabolism of blood meal proteins, we investigated the incorporation of 15N from 15NH4Cl into amino acids using an in vitro tissue culture system. Fat body or midgut tissues from female mosquitoes were incubated in an Aedes saline solution supplemented with glucose and 15NH4Cl for 10-40min. The media were then mixed with deuterium-labeled amino acids, dried and derivatized. The 15N-labeled and unlabeled amino acids in each sample were quantified by mass spectrometry techniques. The results demonstrate that both tissues efficiently incorporate ammonia into amino acids, however, the specific metabolic pathways are distinct. In the fat body, the 15N from 15NH4Cl is first incorporated into the amide side chain of Gln and then into the amino group of Gln, Glu, Ala and Pro. This process mainly occurs via the glutamine synthetase (GS) and glutamate synthase (GltS) pathway. In contrast, 15N in midgut is first incorporated into the amino group of Glu and Ala, and then into the amide side chain of Gln. Interestingly, our data show that the GS/GltS pathway is not functional in the midgut. Instead, midgut cells detoxify ammonia by glutamate dehydrogenase, alanine aminotransferase and GS. These data provide new insights into ammonia metabolism in A. aegypti mosquitoes.
KW - Labeled amino acids
KW - Mass spectrometry
KW - Metabolic pathways
KW - Nitrogen compounds
UR - http://www.scopus.com/inward/record.url?scp=77955171464&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77955171464&partnerID=8YFLogxK
U2 - 10.1016/j.jinsphys.2010.02.016
DO - 10.1016/j.jinsphys.2010.02.016
M3 - Article
C2 - 20206632
AN - SCOPUS:77955171464
SN - 0022-1910
VL - 56
SP - 1040
EP - 1049
JO - Journal of Insect Physiology
JF - Journal of Insect Physiology
IS - 9
ER -