Ammonia metabolism in Aedes aegypti

Scaraffia, Patricia Y.; Isoe, Jun; Murillo, Adrian; Wells, Michael A.

doi:10.1016/j.ibmb.2005.01.012

Cited by 72 publications

(86 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This hypothesis has been somehow neglected so far (but see : Miller and Yellowlees, 1989;Wang and Douglas, 1998;Yellowlees et al, 2008) based on evidence that GS/GOGAT cycle, the fastest route for incorporating ammonium into amino acids through glutamate, is not widespread in animals. However, recent studies demonstrated that GS/GOGAT cycle is active in several metazoans (Scaraffia et al, 2005;Hansen and Moran, 2011) and our analyses using BLAST algorithm (Altschul et al, 1990) indicate that transcripts encoding proteins with high similarities to the domains of GOGAT are present in two cnidarian genomes (Nematostella vectensis (Sullivan et al, 2006), genBank accession number: XP_001630774.1; Acropora digitifera (Shinzato et al, 2011), http://marinegenomics.oist.jp/acropora _digitifera/, gene ID: aug_v2a.08445.t1; Supplementary Table S2). In congruence with the rapid 15 N-enrichment observed in the coral tissue by Single-cell view of ammonium assimilation in corals M Pernice et al NanoSIMS after the pulse of 15 N-ammonium enriched seawater, the results of these BLAST searches suggest that coral hosts could use GS/GOGAT cycle to rapidly fix seawater-derived ammonium into amino acids.…”

Section: Resultsmentioning

confidence: 99%

A single-cell view of ammonium assimilation in coral–dinoflagellate symbiosis

et al. 2012

View full text Add to dashboard Cite

Assimilation of inorganic nitrogen from nutrient-poor tropical seas is an essential challenge for the endosymbiosis between reef-building corals and dinoflagellates. Despite the clear evidence that reef-building corals can use ammonium as inorganic nitrogen source, the dynamics and precise roles of host and symbionts in this fundamental process remain unclear. Here, we combine high spatial resolution ion microprobe imaging (NanoSIMS) and pulse-chase isotopic labeling in order to track the dynamics of ammonium incorporation within the intact symbiosis between the reefbuilding coral Acropora aspera and its dinoflagellate symbionts. We demonstrate that both dinoflagellate and animal cells have the capacity to rapidly fix nitrogen from seawater enriched in ammonium (in less than one hour). Further, by establishing the relative strengths of the capability to assimilate nitrogen for each cell compartment, we infer that dinoflagellate symbionts can fix 14 to 23 times more nitrogen than their coral host cells in response to a sudden pulse of ammoniumenriched seawater. Given the importance of nitrogen in cell maintenance, growth and functioning, the capability to fix ammonium from seawater into the symbiotic system may be a key component of coral nutrition. Interestingly, this metabolic response appears to be triggered rapidly by episodic nitrogen availability. The methods and results presented in this study open up for the exploration of dynamics and spatial patterns associated with metabolic activities and nutritional interactions in a multitude of organisms that live in symbiotic relationships.

show abstract

Section: Resultsmentioning

confidence: 99%

A single-cell view of ammonium assimilation in coral–dinoflagellate symbiosis

et al. 2012

View full text Add to dashboard Cite

show abstract

“…In the silkworm, GltS activity is associated with nitrogen recycling through the GS/GltS cycle; GltS activation in the posterior silk glands allows enhanced utilization of nitrogen (in the form of glutamate converted from glutamine) for the synthesis of silk protein (33)(34)(35). In the mosquito, GS/GltS activity is linked to ammonia detoxification; following a blood meal, GS and GltS are highly expressed in the fat body (32), the main tissue involved in ammonia detoxification (36).…”

Section: Gln Glnmentioning

confidence: 99%

Aphid genome expression reveals host–symbiont cooperation in the production of amino acids

Hansen

Moran

2011

Proc. Natl. Acad. Sci. U.S.A.

365

478

View full text Add to dashboard Cite

The evolution of intimate symbiosis requires the coordination of gene expression and content between the distinct partner genomes; this coordination allows the fusion of capabilities of each organism into a single integrated metabolism. In aphids, the 10 essential amino acids are scarce in the phloem sap diet and are supplied by the obligate bacterial endosymbiont ( Buchnera ), which lives inside specialized cells called bacteriocytes. Although Buchnera ’s genome encodes most genes for essential amino acid biosynthesis, several genes in essential amino acid pathways are missing, as are most genes for production of nonessential amino acids. Additionally, it is unresolved whether the supply of nitrogen for amino acid biosynthesis is supplemented by recycling of waste ammonia. We compared pea aphid gene expression between bacteriocytes and other body tissues using RNA sequencing and pathway analysis and exploiting the genome sequences available for both partners. We found that 26 genes underlying amino acid biosynthesis were up-regulated in bacteriocytes. Seven of these up-regulated genes fill the gaps of Buchnera ’s essential amino acid pathways. In addition, genes underlying five nonessential amino acid pathways lost from Buchnera are up-regulated in bacteriocytes. Finally, our results reveal that two genes, glutamine synthetase and glutamate synthase, which potentially work together in the incorporation of ammonium nitrogen into glutamate (GOGAT) cycle to assimilate ammonia into glutamate, are up-regulated in bacteriocytes. Thus, host gene expression and symbiont capabilities are closely integrated within bacteriocytes, which function as specialized organs of amino acid production. Furthermore, the GOGAT cycle may be a key source of nitrogen fueling the integrated amino acid metabolism of the aphid– Buchnera partnership.

show abstract

“…This is the time of greatest amino acid accumulation in the mosquito and represents a period of stress due to high rates of nitrogenous waste production. Amino acid catabolism releases the toxic by-product NH 4 + (Scaraffia et al, 2005;Isoe & Scaraffia, 2013). NH 4 + toxicity is minimized through a three-phase strategy of fixation, assimilation and excretion (Isoe & Scaraffia, 2013).…”

Section: Nh 4 +mentioning

confidence: 99%

Transport of H+, Na+ and K+ across the posterior midgut of blood-fed mosquitoes (Aedes aegypti)

Pacey

O’Donnell

2014

Journal of Insect Physiology

View full text Add to dashboard Cite

Mosquitoes pose significant threats to human health because they act as vectors for disease causing viruses and protozoans. Indeed, Aedes aegypti is known as the Yellow Fever Mosquito because of its role as a vector for viral infections that kill thousands of people each year. A more thorough understanding of mosquito physiology will aid development of novel control strategies. Previous work on ion transport across the midgut has been focused primarily on larval A. aegypti, while research on the midgut of the adult stage is less complete. The posterior midgut of the adult female is of particular interest because it is used for the storage and digestion of the blood meal which is required for the production of eggs. This study used an array of electrophysiological methodologies such as the Scanning Ion Electrode Technique (SIET) in order to elucidate the patterns and mechanisms of Na + , H + and K + transport across the posterior midgut at intervals during postprandial diuresis and digestion of the blood meal. Measurements of transepithelial potential indicated that the lumen was at its most negative (-13.2 mV) three hours after the blood meal and then gradually became less negative during the time course of digestion. Na + was absorbed (from lumen to bath) at all intervals after the blood meal (6 min, 30 min, 2h, 24 h); calculations of the electrochemical potential indicated that absorption required active transport. H + absorption at all times (6 min -48 h) after the blood meal was also active (i.e. against the electrochemical gradient for H + ) and was greatly reduced by inhibition of carbonic anhydrase. K + transport across the midgut exhibited two distinct phases. During diuresis, luminal concentrations of K + were in the range 24 -28 mM and secretion into the midgut was opposed by the electrochemical iv gradient, indicating active transport. After diuresis, during blood meal digestion, concentrations of K + in the midgut contents were high (95 -134 mM) and absorption of K + was favoured by the electrochemical gradient. K + absorption was sensitive to the channel blocker Ba 2+ during this period.v Acknowledgements

show abstract

Ammonia metabolism in Aedes aegypti

Cited by 72 publications

References 33 publications

A single-cell view of ammonium assimilation in coral–dinoflagellate symbiosis

A single-cell view of ammonium assimilation in coral–dinoflagellate symbiosis

Aphid genome expression reveals host–symbiont cooperation in the production of amino acids

Transport of H+, Na+ and K+ across the posterior midgut of blood-fed mosquitoes (Aedes aegypti)

Contact Info

Product

Resources

About