Inhibition of Sodium-Hydrogen Antiport by Antibodies to NHA1 in Brush Border Membrane Vesicles from Whole Aedes aegypti Larvae.

The present research report describes Na/H antiport by brush border membrane vesicles isolated from whole larvae of Aedes aegypti (AeBBMVw). Our hypothesis is that acid quenching of acridine orange by AeBBMVw is predominantly mediated by Na/H antiport via the NHA1 component of the AeBBMVw in the absence of amino acids and ATP. AeNHA1 is a Na/H antiporter that has been postulated to exchange Na and H across the apical plasma membrane in posterior midgut of A.

K+ pump: from caterpillar midgut to human cochlea.

Deafness is a serious condition that affects millions of people and can also lead to dementia. Moreover, Karet and associates reported in 1999 that mutations in the gene encoding H(+) V-ATPase subunit B(1) lead to deafness. Yet ionic flows that enable humans to hear high-pitched sounds at 20,000 cycles/sec (20 kHz) are not well understood.

High affinity (3)H-phenylalanine uptake by brush border membrane vesicles from whole larvae of Aedes aegypti (AaBBMVw).

Brush border membrane vesicles from whole Aedes aegypti larvae (AaBBMVw) are confirmed to be valid preparations for membrane transport studies. The Abdul-Rauf and Ellar method was used to isolate AaBBMVw that were frozen, stored for several months, transported to a distant site, thawed and used to study Na(+)-coupled, (3)H-labeled, phenylalanine (Phe) uptake. The affinity for all components of the uptake was very high with half maximal values in the sub-micromolar range.

Localization of two Na+- or K+-H+ antiporters, AgNHA1 and AgNHA2, in Anopheles gambiae larval Malpighian tubules and the functional expression of AgNHA2 in yeast.

The newly identified metazoan Na(+)/H(+) antiporter (NHA) family is represented by two paralogues, AgNHA1 and AgNHA2, in the genome of the African malaria mosquito, Anopheles gambiae. Both antiporters are postulated to be electrophoretic i.e.

Countering a bioterrorist introduction of pathogen-infected mosquitoes through mosquito control.

The release of infected mosquitoes or other arthropods by bioterrorists, i.e., arboterrorism, to cause disease and terror is a threat to the USA.

H(+) V-ATPase-energized transporters in brush border membrane vesicles from whole larvae of Aedes aegypti.

Brush border membrane vesicles (BBMVs) from Whole larvae of Aedes aegypti (AeBBMVWs) contain an H(+) V-ATPase (V), a Na(+)/H(+) antiporter, NHA1 (A) and a Na(+)-coupled, nutrient amino acid transporter, NAT8 (N), VAN for short. All V-ATPase subunits are present in the Ae. aegypti genome and in the vesicles.

Voltage coupling of primary H+ V-ATPases to secondary Na+- or K+-dependent transporters.

This review provides alternatives to two well established theories regarding membrane energization by H(+) V-ATPases. Firstly, we offer an alternative to the notion that the H(+) V-ATPase establishes a protonmotive force (pmf) across the membrane into which it is inserted. The term pmf, which was introduced by Peter Mitchell in 1961 in his chemiosmotic hypothesis for the synthesis of ATP by H(+) F-ATP synthases, has two parts, the electrical potential difference across the phosphorylating membrane, Deltapsi, and the pH difference between the bulk solutions on either side of the membrane, DeltapH.

Cloning and functional expression of the first eukaryotic Na+-tryptophan symporter, AgNAT6.

The nutrient amino acid transporter (NAT) subfamily of the neurotransmitter sodium symporter family (NSS, also known as the solute carrier family 6, SLC6) represents transport mechanisms with putative synergistic roles in the absorption of essential and conditionally essential neutral amino acids. It includes a large paralogous expansion of insect-specific genes, with seven genes from the genome of the malaria mosquito, Anopheles gambiae. One of the An.

NHE(VNAT): an H+ V-ATPase electrically coupled to a Na+:nutrient amino acid transporter (NAT) forms an Na+/H+ exchanger (NHE).

Glycolysis, the citric acid cycle and other metabolic pathways of living organisms generate potentially toxic acids within all cells. One ubiquitous mechanism for ridding cells of the acids is to expel H(+) in exchange for extracellular Na(+), mediated by electroneutral transporters called Na(+)/H(+) exchangers (NHEs) that are driven by Na(+) concentration gradients. The exchange must be important because the human genome contains 10 NHEs along with two Na(+)/H(+) antiporters (NHAs).

Larval anopheline mosquito recta exhibit a dramatic change in localization patterns of ion transport proteins in response to shifting salinity: a comparison between anopheline and culicine larvae.

Mosquito larvae live in dynamic aqueous environments, which can fluctuate drastically in salinity due to environmental events such as rainfall and evaporation. Larval survival depends upon the ability to regulate hemolymph osmolarity by absorbing and excreting ions. A major organ involved in ion regulation is the rectum, the last region for modification of the primary urine before excretion.

Synergy and specificity of two Na+-aromatic amino acid symporters in the model alimentary canal of mosquito larvae.

The nutrient amino acid transporter (NAT) subfamily is the largest subdivision of the sodium neurotransmitter symporter family (SNF; also known as SLC6; HUGO). There are seven members of the NAT population in the African malaria mosquito Anopheles gambiae, two of which, AgNAT6 and AgNAT8, preferably transport indole- and phenyl-branched substrates, respectively. The relative expression and distribution of these aromatic NATs were examined with transporter-specific antibodies in Xenopus oocytes and mosquito larval alimentary canal, representing heterologous and tissue expression systems, respectively.

Cationic pathway of pH regulation in larvae of Anopheles gambiae.

Anopheles gambiae larvae (Diptera: Culicidae) live in freshwater with low Na(+) concentrations yet they use Na(+) for alkalinization of the alimentary canal, for electrophoretic amino acid uptake and for nerve function. The metabolic pathway by which larvae accomplish these functions has anionic and cationic components that interact and allow the larva to conserve Na(+) while excreting H(+) and HCO(3)(-). The anionic pathway consists of a metabolic CO(2) diffusion process, carbonic anhydrase and Cl(-)/HCO(3)(-) exchangers; it provides weak HCO(3)(-) and weaker CO(3)(2-) anions to the lumen.

Molecular cloning, phylogeny and localization of AgNHA1: the first Na+/H+ antiporter (NHA) from a metazoan, Anopheles gambiae.

We have cloned a cDNA encoding a new ion transporter from the alimentary canal of larval African malaria mosquito, Anopheles gambiae Giles sensu stricto. Phylogenetic analysis revealed that the corresponding gene is in a group that has been designated NHA, and which includes (Na+ or K+)/H+ antiporters; so the novel transporter is called AgNHA1. The annotation of current insect genomes shows that both AgNHA1 and a close relative, AgNHA2, belong to the cation proton antiporter 2 (CPA2) subfamily and cluster in an exclusive clade of genes with high identity from Aedes aegypti, Drosophila melanogaster, D.

Molecular characterization of the first aromatic nutrient transporter from the sodium neurotransmitter symporter family.

Nutrient amino acid transporters (NATs, subfamily of sodium neurotransmitter symporter family SNF, a.k.a.

Ancestry and progeny of nutrient amino acid transporters.

The biosynthesis of structural and signaling molecules depends on intracellular concentrations of essential amino acids, which are maintained by a specific system of plasma membrane transporters. We identify a unique population of nutrient amino acid transporters (NATs) within the sodium-neurotransmitter symporter family and have characterized a member of the NAT subfamily from the larval midgut of the Yellow Fever vector mosquito, Aedes aegypti (aeAAT1, AAR08269), which primarily supplies phenylalanine, an essential substrate for the synthesis of neuronal and cuticular catecholamines. Further analysis suggests that NATs constitute a comprehensive transport metabolon for the epithelial uptake and redistribution of essential amino acids including precursors of several neurotransmitters.

K+ amino acid transporter KAAT1 mutant Y147F has increased transport activity and altered substrate selectivity.

KAAT1, a K(+)-coupled, neutral amino acid transporter from larval insect midgut, differs from other members of the Na(+):neurotransmitter transporter family (SNF) in two important ways: (1) it transports nutrient L-, alpha-amino acids, rather than neurotransmitters such as gamma-aminobutyric acid (GABA), and (2) it accepts K(+) as well as Na(+) as a co-substrate. To determine whether the restoration of KAAT1 residues to their GABA transporter GAT1 cation-binding equivalents might abolish its K(+) but not its Na(+) recognition site, we constructed a multiple mutant in which nine divergent KAAT1 residues were mutated back to the conserved form of the superfamily. To investigate the amino-acid-binding site, we constructed several single mutants that had been identified in GAT1.

Consensus guidelines on analgesia and sedation in dying intensive care unit patients.

Background: Intensivists must provide enough analgesia and sedation to ensure dying patients receive good palliative care. However, if it is perceived that too much is given, they risk prosecution for committing euthanasia. The goal of this study is to develop consensus guidelines on analgesia and sedation in dying intensive care unit patients that help distinguish palliative care from euthanasia.

Conserved tyrosine-147 plays a critical role in the ligand-gated current of the epithelial cation/amino acid transporter/channel CAATCH1.

CAATCH1 functions both as an amino-acid-gated cation channel and as a cation-dependent, proline-preferring, nutrient amino acid transporter in which the two functions are thermodynamically uncoupled. This study focuses on the ionic channel aspect, in which a Tyr(147) (wild type) to Phe(147) (Y147F) site-directed mutation was investigated by steady-state electrophysiological measurements in the Xenopus laevis oocyte expression system. This tyrosine residue is conserved within the third transmembrane domain in members of the Na(+):neurotransmitter transporter family (SNF), where it plays a role in binding pharmacological ligands such as cocaine to the serotonin (SERT), dopamine (DAT) and norepinephrine (NET) transporters.

High-resolution microanalysis of nitrite and nitrate in neuronal tissues by capillary electrophoresis with conductivity detection.

Nitrites and nitrates are widely used reporters of endogenous activity of nitric oxide synthases (NOS), an important group of enzymes producing the gaseous signal molecule nitric oxide (NO). However, due to the great chemical heterogeneity of neuronal tissues, standard analytical protocols for evaluation of neuronal nitrite/nitrate concentrations are inefficient. We optimized a high-performance capillary zone electrophoresis (CZE) technique to analyze nitrite/nitrate concentrations in submicroliter samples from mammalian neuronal tissues.