Fatty acid desaturases can introduce double bonds into the hydrocarbon chains of fatty acids to produce unsaturated fatty acids. In the present study, 29 full-length desaturase genes were identified from soybean genome by a thorough annotation exercise. A comprehensive analysis was performed to characterize phylogeny, chromosomal locations, structures, conserved motifs, and expression patterns of those genes. The soybean genes were phylogenetically clustered into nine subfamilies with the Arabidopsis counterparts, FAB2, FAD2, FAD3, FAD5, FAD6, FAD7, FAD8, SLD1, and DES1. Twenty-nine desaturase genes were found to be distributed on at least 15 of the 20 soybean chromosomes. The gene structures and motif compositions were considerably conserved among the subfamilies. The majority of desaturase genes showed specific temporal and spatial expression patterns across different tissues and developmental stages based on microarray data analyses. The study may provide new insights into the origin and evolution of fatty acid biosynthesis pathways in higher plants. Additionally, the characterization of desaturases from soybean will lead to the identification of additional genes for genetic modification of plants to produce nutritionally important fatty acids.Keywords Glycine max . Genome . Fatty acid desaturase . Phylogenetic analysisΔ5 Desaturase DesC Cyanobacterial Δ9 desaturase DesA Cyanobacterial Δ12 desaturase DesB Cyanobacterial ω3 desaturase
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 15 N from 15 NH 4 Cl 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 15 NH 4 Cl for 10-40 minutes. The media was then mixed with deuterium-labeled amino acids, dried and derivatized. The 15 N-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 15 N from 15 NH 4 Cl 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, 15 N 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.
Keywordslabeled amino acids; metabolic pathways; mass spectrometry; nitrogen compounds
1-INTRODUCTIONAedes aegypti mosquitoes are vectors of medical importance. During blood feeding, A. aegypti females are able to transmit viruses that produce serious infectious diseases such as Dengue fever and Yellow fever causing significant morbidity and mortality worldwide. In recent years, the A. aegypti populations have been spread significantly increasing the risk of Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Certainly, A. aegypti females are a remarkable biological system. In spite of the vast amount of blood meal proteins that females ingest in a short time, and the tremendous amino acid oxidation that occurs during blood metabolism (Zhou et al., 2004), A. aegypti females are able to utilize dietary nutrients and efficiently remove toxic compounds and excess nitrogen. It is of interest to uncover the metabolic mechanisms that A. aegypti female mosquitoes use to avoid toxic accumulation of ammonia in the tissues, which result from massive amino acid deamination, in order to potentially develop new strategies for vector control. In this article, the term "ammonia" refers to...
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